Regional Groups of Mössbauer Researchers - India
Reprinted from the May 2005 edition of the Mössbauer Spectroscopy Newsletter, published as part of Volume 28, Issue 5 of the Mössbauer Effect Reference and Data Journal
Mössbauer Spectroscopy in India

This issue of the Newsletter features reports from 13 active Mössbauer research laboratories in India. The reports appear in descending order of most active Indian institutions based on the records of the Mössbauer Effect Data Center.


Department of Physics
Indian Institute of Technology Kanpur
Kanpur

Names and Titles of Researchers

Prof. H. C. Verma

Mukesh Kumar Roy – Ph.D. Student

Brajesh Pandey – Ph.D. Student

H. C. Verma (center) and his students Mukesh Kumar Roy (right) and
Brajesh Pandey (left).

Description and Areas of Research

The core group of 57Fe Mössbauer spectroscopy is headed by Prof. H. C. Verma. Two Ph.D. students, Mr. Mukesh Kumar Roy and Mr. Brajesh Pandey, are part of the core group. The group collaborates with several research groups, both within IIT Kanpur and outside the facility. The main collaborator groups are:

Prof. Sanjeeva Bhargava

Materials and Metallurgical Engineering Department, IIT Kanpur


Sanjeeva Bhargava (right) and his student Anandrao (left).

Dr. R. P. Das and Dr. Shashi Anand

Regional Research Laboratory, Bhubneshwar


R. P. Das (right), Shashi Anand (left), and their student
Mamata Mohapatra (middle).

Dr. R. P. Tripathi and Dr. Amita Tripathi

Department of Physics, Jai Narain Vyas University, Jodhpur


R. P. Tripathi (left) and Amita Tripathi (right).

The group’s research interests are quite wide. The main areas of current research (in the last years) are as follows:

  • Fe-Based Alloys: The group has extensively studied alloys based on DO3 Fe3Al. In particular, the phase changes during mechanical deformation have been investigated. Often, samples for Mössbauer spectroscopy are made by filing an ingot formed in induction or arc furnace. The group’s work has shown that the original phase may be completely changed during the process.

The effect of dilute substitution of Fe by Ti, Cr, Mn, etc. on the deformation and its recovery on controlled heating has been studied.

The group prepared alloys of immiscible systems such as Fe-Ag and Fe-Cu by simultaneous electrodeposition of cations under optimized conditions. Mössbauer spectroscopy and supporting studies have established that a wide range of compositions can be obtained without segregation, though the equilibrium solid solubility is too small.

They are studying alloys made by mechanical milling of the elemental powders. Prof. Sanjeeva Bhargava collaborates in these studies.

  • Magnetic Nanoparticles: The group synthesized a number of compounds, mainly spinel ferrites, by various chemical reactions. Mössbauer spectroscopy was extensively used to see the cationic distribution in different sites. ZnFe2O4 from 4 nm onwards prepared by the group was shown to have quite anomalous temperature dependence of electron density at nuclear sites as shown by isomer shift studies. The effect of different process parameters on magnetic properties has been studied. Temperature dependent Mössbauer spectroscopy has been effectively utilized in studying superparamagnetism in these nanosized compounds.

Preparation of goethite, hematite, and magnetite under various chemical conditions and the effect of metallic cation presence in the reaction vessel are extensively studied. These studies are used to evolve more effective processes for separation of metals from the ores, which is one of the major projects of the Regional Research Laboratory Bhubneswar. Dr. R. P. Das and Dr. Shashi Anand are collaborating in these Mössbauer studies.

Deformation and its recovery on controlled heating has been studied.

Recently, the group has started working in the area of dilute magnetic semiconductors.

  • Geological Boundaries: The group is using Mössbauer spectroscopy to study the sequences of events that led to mass extinction of species at various geological times. They have especially concentrated on the Cretaceous–Tertiary boundary, 65 million years ago, when about 50% of life forms, including the mighty dinosaurs, were killed. There are many unanswered questions that they have identified, based on the iron–mineralogy of the sedimentary samples deposited at the boundary times, and they are trying to find answers.

From the Mössbauer studies of sediments, the group has suggested that the most disastrous mass extinction at the Permian-Triassic boundary (250 million years ago) may also be a result of a massive impact by an extraterrestrial object. Prof. R. P. Tripathi and Dr. Amita Tripathi are collaborating in these studies.

  • Meteoritic Studies: The group is also using Mössbauer spectroscopy to study meteorites. They have suggested certain systematics in the iron phases occurring in H, L, and LL-type ordinary chondrites and these systematics are being used by various researchers to assist classification of meteorites. Among the meteorites studied are ordinary chondrites and HED meteorites. Prof. R. P. Tripathi is collaborating in these studies.

The group’s facilities include the following equipment:

  • Room temperature 57Fe Mössbauer spectroscopy
  • Room temperature Conversion Electron Mössbauer Spectroscopy with home-made flow type He-ethane detector
  • Low temperature Mössbauer spectroscopy (up to 15 K) with close cycle refrigeration cryostat
  • High temperature Mössbauer spectroscopy at 450 K
  • Room temperature Mössbauer spectroscopy in an applied magnetic field (up to 1.5 tesla)

Solid State Chemistry and Nanomaterials Laboratory
Department of Chemistry
Indian Institute of Technology Kanpur
Kanpur


From left to right: Dillip Kr. Panda, Sajith Kurian, R. S.
Ningthoujam,George M. Paily, N. Sudhakar, Sayan
Bhattacharyya,N. S. Gajbhiye,Kemchand Dewangan, Satish
Sharma,Sachil Sharma, Raj Kumar Das.

Names and Titles of Present Group Members

N. S. Gajbhiye – Professor and Group Leader

Sayan Bhattacharyya – Ph.D. Student
Sachil Sharma – Ph.D. Student
Khemchand Dewangan – Ph.D. Student
Dillip Kr. Panda – Ph.D. Student
Sajith Kurian – Ph.D. Student
Rajkumar Das – M.Sc. Student
George M. Paily – M.Sc. Student
Neeladri Sekhar Karan – M.Sc. Student
N. Sudhakar – Senior Scientist
Sarita Rai – Research Associate
Lyci George – Research Associate
Prashant K. Pandey – Research Associate
Satish Sharma – Visiting Professor
Anupriya Agarwal – Project Student

Names and Titles of Past Group Members

V. K. Sankaranarayanan – Ph.D. 1991
Seema Prasad – Ph.D. 1997
Vijayalakshmi – Ph.D. 1998
R. N. Panda – Ph.D. 1999
G. Balaji – Ph.D. 2004
Sanjay Srivastava – Ph.D. 2004
R. S. Ningthoujam – Ph.D. 2005
Ashwini Tiwari – M.Sc. 2000
Susmita Basak – M.Sc. 2004
A. P. Mishra – Visiting Professor, 2004

Description and Areas of Research

The main research lines at the Solid State Chemistry and Nanomaterials Laboratory at the Indian Institute of Technology Kanpur (IITK) involve the synthesis of advanced materials and nanostructured materials and investigations of their structural, electronic, transport, and magnetic properties. The measurements on magnetic materials include solely the instrumental techniques: Mössbauer spectroscopy, vibrating sample magnetometer, SQUID, and FMR. The data on magnetism of nanostructured systems are analyzed and compared with the microscopic theories to understand the basic phenomena underlying these systems.

The Mössbauer Spectroscopy Research Laboratory is a part of the Solid State Chemistry and Nanomaterials Division. The research activities of the group range from synthesis and characterization to the measurement of physical properties to analyze and establish the structure property relationships. This involves wide interdisciplinary areas, including chemistry, materials science, and physics. Prof. Gajbhiye’s group has published more than 100 research papers in reputed national and international journals, besides several conference proceedings. Based on the scientific research, some development work on PTC-thermistors, ferrofluids, and thermal barrier coatings have resulted in the technology transfer to industries.


N. S. Gajbhiye
Also, in recent times, many Ph.D. and M.Sc. degrees have been awarded to the research scholars under the supervision of Professor Gajbhiye.

The research group has active collaborations with various research institutions and groups in India and abroad, including:

  • Institute of Nanotechnology, Forschungszentrum Karlsruhe, Germany (Professor H. Gleiter, Professor H. Hahn, and Dr. Joerg Weissmüller)
  • Materials Science Department, Darmstadt University of Technology, Germany (Dr. Mohammad Ghafari, Professor H. Hahn)
  • National Physical Laboratory, New Delhi (Dr. S. M. Shivaprasad, Dr. V. Sankarnarayanan)
  • Tata Institute of Fundamental Research, Mumbai (Professor A. K. Nigam)
  • Defence Materials and Stores Research and Development Establishment, Kanpur (Dr. G. N. Mathur)
  • Department of Physics, IITK (Dr. K. P. Rajeev)

Besides other academic activities, the group has focused research programs towards nanomagnetism, finite-size effects, phase transitions at lower temperatures, local electron distribution, and atomic disorder, where Mössbauer spectroscopy is used extensively. The Mössbauer Spectroscopy Laboratory facilities consist of the low temperature Mössbauer cryostat system, which records the spectra down to 5 K, and a CEMS set-up that functions at the liquid nitrogen temperature.

The various research projects/areas of the group include the following topics:

  • Magnetism of nanostructured materials (garnets, spinel ferrites, hexagonal ferrites)
  • Electronic structure, transport, and magnetic properties of nano-size binary, ternary transition metal nitrides and composite nitride materials
  • Electronic ceramics: BaTiO3, SrTiO3, PZT, PLZT; tetra - ZrO2 (TSZ / PSZ)
  • Electronic structure and magnetism properties of self assembled monodisperse nanoparticles of metals and metal composites: Co, Ni, Fe, Pd, Pt, Au, Ag, Co-Pt, NiAg, FePt, NiCu
  • Catalytic studies using nanoporous support and nanomaterials
  • Hydrogen storage and phase transition studies in metal hydrides and alanates
  • Nano-sensors for forensic applications

Significant results are obtained with room temperature 57Fe Mössbauer spectroscopy on ultrafine (nanosize) rare-earth iron garnets (RIG) having compositions R3Fe5O12 [where R = Sm, Tb, Dy, Er, Yb, (YGd), and (Ynd)]. Mössbauer spectroscopy is applied to many nanosystems in order to reveal microstructural and magnetic aspects of nanocrystalline ferrites, including the pure and substituted spinel ferrites MFe2O4 (M = Mn, Co, Ni, Cu) and hexaferrites MFe12O19 (M = Ba, Sr, Pb) that are synthesized by chemical routes.

One of the notable contributions of this group is the detailed investigations of nanoparticulate systems for core-shell structure and the finite size scaling effects from the low temperature magnetic and Mössbauer spectroscopy studies, invoking canted spin structure or magnetic dead layer or structural rearrangements at the surface of ferrite nanoparticles.

This group has performed the synthesis of various stable and metastable phases of metal nitride systems as nanocrystalline materials having tunable magnetic and electrical properties. The Fe containing nitride phases were synthesized in the size range, 5-30 nm as: γ-Fe4N, γ-Fe4-xNixN, γ-Fe-Ni-N, ε-Fe3N, ε-Fe3-xCoxN, ε-Fe3-xNixN (0.0 ≤ x ≤ 0.8), Fe3Mo3N including the innovative new phase FeMoN2. It is observed that the intrinsic magnetic properties vary significantly due to their nanocrystalline nature and also due to the presence of a thin surface oxide layer as magnetic dead layer.

Among the other transition metal nitrides (without Fe), the superconducting and electrical properties of pure and doped metal nitrides VN, Ni3N, MoN, Mo2N, TiN, CoN, Co4N, Co3Mo3N, CoMoN2, and MnWN2 are deeply investigated. The superconducting transition Tc is found to vary with the amount and the nature of dopants and interestingly the nanocrystallite nature. This is due to the electron-electron, electron-phonon interactions and the spin fluctuation phenomena. Spin-glass like ordering is observed in the Fe containing nitride materials having composite structures involving the core-shell morphology. The recent interest in this regard is based on the generation of spin-glass like ordering from random exchange anisotropy (exchange bias) at the random interfaces of the nitride nanoparticles. The core-shell morphology and other aspects are studied with in-depth analysis by X-ray photoelectron spectroscopy and these results are corroborated with the magnetic and Mössbauer studies.

Besides the ferrites, oxides, and nitrides, advanced electronic ceramic materials such as the lead zirconate titanate (PZT) are synthesized as nanophase and the research is in progress for developing the expertise for the control and improvement of electrical (dielectric/piezoelectric) properties, when obtained as nanostructured PZT bulk materials and the nanocomposite polymeric systems.

Extensive research work is in progress on the synthesis of electronic and magnetic properties of self-assembled monodisperse metal nanoparticles and nanocomposites: Pd, Ag, Au, Co, Ni, FePt, PdCo, NiAg, etc. Some of these systems are investigated for their magnetic microstructures/nanostructures with the help of Mössbauer spectroscopy and X-ray photoelectron spectroscopy techniques. Also, simultaneous work is in progress to apply these nanomaterials (various oxide and nitride systems) as nanocatalytic materials supported on very high surface area of nano-porous materials for the various catalytic processes, particularly in organic reactions and hydrogen storage applications, including the metal alanates. By using these nanomaterials, the fabrication of nanosensors are also underway that would be used for the forensic science applications.


Department of Physics
Devi Ahilya University

and

University Grants Commission (UGC)-Department of Atomic Energy (DAE)
Consortium for Scientific Research
Indore

Names and Titles of Researchers

Prof. Ajay Gupta

Dr. Shashank Kane – Physics Department, Devi Ahilya University

Dr. Ratnesh Gupta – Institute of Instrumentation, Devi Ahilya University

Dr. V. Raghavendra Reddy – UGC-DAE CSR

Description and Areas of Research

Activities of the Mössbauer spectroscopy group of Prof. Ajay Gupta at Indore are mainly centered around the studies of nanostructured materials, including nanoparticles, thin films, and multilayers. Other fields of interest include oxide materials, minerals, and alloys. In soft magnetic nanocrystalline alloys of compositions around FINEMET and HITPERM alloys, as well as multi-component bulk metallic glasses, Mössbauer spectroscopy is used to obtain both structural and magnetic information. In thin films and multilayers, the current interest of the group lies in soft magnetic thin films with amorphous and nanocrystalline compositions; granular composite magnetic films; tailoring the magnetic properties by irradiation with heavy ions in the energy range of a few hundred keV to a few hundred MeV; multilayers exhibiting perpendicular magnetic anisotropy (e.g., Fe/Pt, Fe/Pd, Fe/Tb); and GMR multilayers such as Fe/Cr. Mössbauer spectroscopy is combined with X-ray and neutron reflectivity for a detailed characterization of interfaces.


Ajay Gupta

Activities of the group started in 1983 in the Physics Department of Devi Ahilya University. At present the group consists of five faculty members at UGC-DAE Consortium for Scientific Research and Devi Ahilya University, and 10 research scholars. The facilities include two Mössbauer spectrometers from WissEl, which are routinely used in both transmission and back-scattering geometries. Transmission measurements can be done down to 15 K using a closed-cycle refrigerator. For going down to temperatures of 4.2 K, a home-made liquid helium cryostat is available. An Oxford cryostat capable of going down to 1.2 K and 8 T of magnetic field is also available, which is fitted with field cancellation coils and mylar window. A Mössbauer insert for this system is being developed for doing measurements in longitudinal field geometry. High temperature measurements up to 1000 K are done using a vacuum furnace. High-pressure Mössbauer measurements up to 35 GPa are being done using a diamond-anvil cell, in collaboration with the High Pressure Division at the Bhabha Atomic Research Center, Mumbai. An ultra-high vacuum chamber for in-situ study of the magnetic properties of ultra-thin films has been fabricated, which is equipped with RHEED, CEMS, and MOKE. At present, the system is under testing. Mössbauer measurements are supplemented by a number of in-house techniques, such as grazing-incidence X-ray diffraction, X-ray reflectivity and diffuse scattering, magneto-optical Kerr effect, atomic force microscopy, low temperature transport and magnetic properties, and differential scanning calorimetry.

Nuclear Resonance Scattering beamlines at E.S.R.F., Grenoble, and SPring8, Japan, are being used for doing nuclear resonance reflectivity and inelastic nuclear resonance scattering studies. The technique of nuclear resonance reflectivity from isotopic multilayers has been developed as a highly precise tool to study self-diffusion of Mössbauer active atoms (e.g., 57Fe) in amorphous and nanocrystalline thin films. Nuclear resonance fluorescence from thin marker layers under X-ray standing wave conditions provides complementary information about diffusion lengths in the range of 1-10 nm. Resonance enhancement of X-rays in thin films has also been used to study vibrational dynamics of 57Fe implanted in amorphous SiO2 with concentration as low as 5x1016 atoms/cm2.

Dr. Shashank Kane, at the Physics Department of Devi Ahilya University, is primarily interested in structural and magnetic investigation of amorphous and nanocrystalline soft magnetic alloys. He also participated in the MER program of NASA and was involved in development and testing of the Miniaturized Mössbauer spectrometer (MIMOS) at Mainz.

Dr. Ratnesh Gupta, at the Institute of Instrumentation of Devi Ahilya University, is primarily interested in the study of magnetic thin films and tailoring their magnetic properties using energetic heavy ions. He was involved in the development of magnetic orientation Mössbauer spectroscopy (MOMS) in collaboration with the group at Göttingen.

Dr. V. Raghavendra Reddy at UGC-DAE CSR is primarily interested in the systems exhibiting PMA, such as Fe/Pt, Fe/Pd, etc., and the development of correlation techniques for improving S/N ratio in stochastic process with special reference to Mössbauer spectroscopy.

The primary mandate of the UGC-DAE Consortium for Scientific Research is to provide state-of-the-art research facilities to scientists from universities and other educational institutions in India. The facility for Mössbauer spectroscopy is utilized extensively by users from all over India to study a variety of systems, such as nanocrystalline ferrites and iron oxides, minerals, meteorites, polymer blends, and Fe implanted samples. Occasionally, users from other countries also approach the group for measurements. Recently, a group from LERMPS – UTBM, Belfort, France, studied thermally sprayed nanocrystalline coatings.


Tata Institute of Fundamental Research
Mumbai


From left to right: R. Nagarajan, A. K. Nigam, and P. L. Paulose.

J. K. Srivastava

Names of Researchers

Prof. J. K. Srivastava
Prof. A. K. Nigam
Prof. P. L. Paulose
Prof. R. Nagarajan – Collaborator

Description and Areas of Research

In the Tata Institute of Fundamental Research (TIFR), Mössbauer spectroscopy work started in 1960 (soon after the discovery of the Mössbauer effect) with the observation of the Mössbauer effect in 161Dy by Prof. S. Jha and coworkers. This work was for nuclear spectroscopy purposes, to confirm the existence of the first excited state at 26 keV in 161Dy. Since then, several researchers at TIFR have developed their own Mössbauer spectroscopy set-ups to be used as a complementary technique in their investigations in solid state physics.

Mössbauer spectroscopy at TIFR, as it was at many places in the early days, has evolved through constant velocity cam drives, sinusoidal speaker drives, constant acceleration drives, etc. Much of the instrumentation needed for the Mössbauer experiments have been indigenously developed at TIFR. Many researchers, too numerous to mention by name here, have contributed to the growth of Mössbauer spectroscopy activity in TIFR. However mention can be made of some of the senior pioneers – like Profs. R. Fatehally, G. Chandra, H. G. Devare, and R. P. Sharma – who contributed in early days. The current activities are going on in the laboratories of Profs. J. K. Srivastava, A. K. Nigam, and P. L. Paulose. Prof. R. Nagarajan, who superannuated very recently and is collaborating, has also a very significant contribution in the current Mössbauer activities of TIFR. These activities, in brief, are described below.

In the course of four and half decades of Mössbauer spectroscopy, a variety of systems have been investigated down to 4.2 K using 57Fe, 119Sn, and 151Eu resonances. Systems investigated include oxide systems (including some investigations in High Tc oxides), Heusler alloys, Chevaral Phase compounds, metallic glasses, spin glasses, and intermetallic alloys. TIFR has the distinction of identification/confirming valence fluctuation of Eu through 151Eu resonance in several Eu-based intermetallics, such as EuPd2Si2, EuNi2P2, EuNiSi2, EuIr2Si2, Eu2Ni3Si5, EuPd3B, and EuRh3B2. The investigations also established fluctuation of Eu valence even in dilute limit in these systems. In the metallic glass (Fe-TM)90Zr10, the hyperfine field distribution was found to be of bimodal nature. Magnetic moment on Rh in the metallic glass system Fe-Rh-B was indirectly inferred from Mössbauer spectroscopic measurements.

Some of the recent work includes: the investigation of manganite systems, such as Nd0.5X0.5MnO3 (X = Ca or Sr), and in Sr2FeMoO6 to look for phase separation, charge order, crystallographic order; investigations on magnetic order in Eu-based Ruthenate ferromagnetic superconductor; and investigations in ferrite systems, both in bulk and in nanocrystalline form. In the future, Mössbauer spectroscopy in externally applied field and in other rare earth resonances are planned. Prof. Nagarajan has been the collaborator for the above Mössbauer spectroscopy work. This part of the Mössbauer activity is being carried forward by Profs. P. L. Paulose and A. K. Nigam. A large number of significant publications have originated from the above works, which are widely referred.

Prof. J. K. Srivastava has been mainly studying oxide samples using the 57Fe Mössbauer spectroscopy technique. Ionic spin relaxation phenomenon and superparamagnetism have been extensively studied. Both self and cross relaxation phenomena have been investigated, and it has been shown that the cross relaxation rate is larger than the self relaxation rate, something which looks opposite to what one can normally think. Based on these studies, several new experiments, such as Mössbauer-ESR Double Resonance (MEDR) and Microwave-Optical-Mössbauer Triple Resonance (MOMTR), have been proposed. Radio frequency (rf) perturbation of Mössbauer resonance has also been studied and Mössbauer lineshape in presence of spin lattice relaxation effects predicted. Magnetic structure of oxides is another area of investigation, where it has been shown for the first time that Al3+ (corundum) doping completely suppresses the hematite Morin transition. This finding has great implication for the anisotropy theory. Spin glass (SG) systems [cubic spinel ferrites and anisotropic (orthorhombic) pseudobrookite and related systems, and few metallic lattices for comparison] and high-Tc (critical temperature) superconductors (doped 123 and related systems) have also been studied, and their Mössbauer lineshapes thoroughly investigated. Based on these studies, two new models have been proposed – the cluster phase transition (CPT) model and the paired cluster (PC) model that, respectively, completely explain the nature and mechanism of SG freezing and high-Tc superconductivity. In the opinion of the researchers, this is a remarkable achievement of Mössbauer spectroscopy.

The work of the laboratory is very well referred in various Mössbauer research books and review articles, including MERDJ review articles. The earlier work is summarized in the prestigious laboratory publication (book) Advances in Mössbauer Spectroscopy: Applications to Physics, Chemistry and Biology, edited by B. V. Thosar, P. K. Iyengar, J. K. Srivastava and S. C. Bhargava (Amsterdam: Elsevier, 1983) [Foreword by Prof. R. L. Mössbauer] and the current laboratory work is summarized in the laboratory publications (books) Models and Methods of High-Tc Superconductivity: Some Frontal Aspects, Vol. 1 & Vol. 2, edited by J. K. Srivastava and S. M. Rao (New York: Nova Science, 2003) [“Horizons in World Physics” series publications].

To summarize, the laboratory has successfully utilized Mössbauer spectroscopy for most important current studies in solid state physics.


Department of Solid State Physics
Indian Association for the Cultivation of Science (IACS)
Kolkata

Names and Titles of Researchers

Prof. Debjani Ghosh – Retired Professor and Ex-Head

Dr. Aparajita Nag (Chattopadhyay) – Lecturer, B.K.C. College

Dr. Y. M. Jana – Lecturer, B.S. College

Dr. G. Y. V. Victor – Deputy Chief Executive Officer, International Seaport Dredging Pvt. Ltd.

Dr. Sulava Das Gupta – Reader, Physics Department, Jadavpur University

Dr. Ajita Sengupta – Senior Lecturer, Bethune College

Ms. Papri Dasgupta – Senior Research Fellow, Solid State Physics Department, IACS


From left to right: Debjani Ghosh, Aparajita
Nag (Chattopadhyay),Papri Dasgupta, and Ajita Sengupta.

Description and Areas of Research

Prof. D. Ghosh received her D.Phil (Science) Degree in 1970 from the Calcutta University in India, in the subject of experimental investigations on magnetic properties of iron group of compounds. Post-doctoral work includes studies of different rare earth crystalline and non-crystalline solids involving low temperature (LT) measurements of magnetization and magnetic susceptibilities, magnetic anisotropies, polarized and fluorescence spectra, specific heat, and Mössbauer spectra. LT measurements were carried out using indigenously built LT cryostat systems and commercial closed cycle He cryogenic systems. Other work includes (a) magnetic and Mössbauer experiments on different magnetic minerals, the results of which have been published in the best journals of the subject area; (b) magnetic, electrical, and other studies on thin films of Cu-Ni alloys of varying thickness; and (c) magnetic measurement on a few nematic liquid crystals. The current interest of Dr. Ghosh is on experimental and theoretical investigations of geometric frustration (GF) and ordering phenomena in some mineral pyrochlore compounds of the type A2B2O7, where A and B are, respectively, trivalent rare earth and tetravalent transition atoms; these compounds are now intensely studied world-wide. Papers published by her group in these systems are frequently cited.

Dr. Ghosh joined the faculty of the Solid State Physics Department of IACS as a Research Assistant (1974) and was subsequently appointed to the posts of Lecturer (1980), Reader (1984), and Professor (1990) in the same department. She published over 120 papers, mostly in internationally recognized journals.

She has guided 12 Ph.D. students, who are now employed as lecturer/reader in colleges and universities, and some of them are pursuing research work. Dr. G. Y. V. Victor, a student of Dr. Ghosh, is presently employed as the Deputy Chief Executive Officer of a marine and dredging MNC, and he is publishing important papers on mineral systems. Another Ph.D. student – Dr. Y. M. Jana, who is a lecturer in a college – was appointed as a Visiting Scientist for a year in 2002 at the Innovation Centre, Kyoto University, for studying GF systems and is presently working at the Grenoble High Magnetic Field Lab., MPI-FKN/CNRS, France, in the area of spintronics.


G. Y. V. Victor (left) and Y. M. Jana (right)

Dr. Ghosh served in various important positions at IACS and elsewhere, and acted as an examiner of post-graduate examinations of different universities. She is a member of several learned societies and educational institutions. She acted as the Director of Publication of the Journal of Cryogenics of India from the early 1980s until 2005.

Some of the work on rare earth compounds included collaboration with the following renowned scientists: Dr. S. Mroczkowski, Applied Physics Department, Yale University, USA; Prof. E. Gmelin, LT Laboratory, Max Planck Institute, Germany; Dr. B. M. Wanklyn, Clarendon Laboratory, UK; and Prof. Y. Maeno, International Innovation Centre, Kyoto University, Japan. Prof. S. Ghose, of the Geological Science Department of Washington University in Seattle, USA, collaborated in some of the mineral studies.


Indian Association for the Cultivation of Science (IACS)
Kolkata

Names and Titles of Researchers

Prof. D. Chakravorty – Group Leader

Mr. Soumen Basu – Senior Research Fellow, IACS

Dr. Pradip Brahma – Reader, Gurudas College, Calcutta University

Dr. Mrinal Pal – Lecturer, Department of Physics, Burdwan University

Dr. Sourish Banerjee – Senior Lecturer, Department of Physics, Calcutta University

Dr. Dipankar Das – Scientist, Inter-University Consortium of Department of Atomic Energy Facilities, Kolkata

Mr. Saurav Datta – Lecturer, Rammohan College, Calcutta University

It should be noted that most of the scientists working in the group belong to other organizations and they carry out their work on a part-time basis.

Description and Areas of Research

The main thrust of this group has been to synthesize different magnetic particles in nanocrystalline forms. The techniques used have been mostly chemical. Sol-gel method has been exploited to prepare nanocomposites comprising metallic nanoparticles in a silica gel matrix. Superparamagnetic relaxation has been observed in the case of iron particles with diameters around 2-4 nm.

Composites of α-Fe and Fe3O4 having dimensions in the range 10-20 nm have been prepared by chemical reduction of μ-sized α-Fe2O3 powders. Mössbauer spectroscopic analysis showed almost 30% of the particles to be superparamagnetic.

Nanocrystalline Ni3Fe particles having diameters in the range 9 to 20 nm were grown within a silica gel matrix. From Mössbauer analysis, it was found that the hyperfine field increased as the particle size became smaller. This indicated that the atomic disorder in the alloy increased with a reduction of the particle size.

Iron core–iron oxide shell nanostructures have been grown within silica gel matrix. These core-shell structures have a percolative configuration. It has been shown that the dc electrical resistivities of these nanocomposites differ substantially from that of the precursor glass composition. An interfacial amorphous phase has been shown to cause this change. Mössbauer spectroscopy is being used to investigate the structural characteristics of the interfaces.


University Grants Commission (UGC)-Department of Atomic Energy (DAE) Consortium for Scientific Research
Kolkata

Names and Titles of Researchers

Dr. Dipankar Das – Group Leader

Mr. Basab Kr. Nath – Senior Research Fellow

Mr. Samrat Mukherjee – Junior Research Fellow

Mr. Sandeep Kr. Chaudhuri – Junior Research Fellow

Description and Areas of Research

The Mössbauer spectroscopy group at the UGC-DAE Consortium for Scientific Research (formerly the Inter-University Consortium for DAE Facilities), Kolkata Centre, has been working for more than a decade in various interdisciplinary topics using Mössbauer spectroscopy as a probe. The Centre has a unique Mössbauer source preparation laboratory and has been preparing and supplying 57Co Mössbauer sources up to 15 mCi strength to various universities and institutions in India. Co-57 activity has been produced using the cyclotron irradiation facility at the Variable Energy Cyclotron Centre, Kolkata. The group’s expertise in source preparation has been utilized to diffuse Co-57 activity into samples containing no iron and performing Mössbauer measurements in the emission geometry.

The Mössbauer facility of the Centre consists of a couple of PC-based spectrometers operating in the constant acceleration mode. One of the spectrometers is equipped with a closed cycle refrigerator (procured from Janis Research Inc., USA); the lowest temperature attainable is 16 K, the temperature stability being 0.001 K. The other spectrometer is dedicated to room temperature studies, including measurements in the backscattering mode. The isotopes available are 57Co, 119Sn, and 151Sm.

A large number of researchers from various Indian universities have used the Mössbauer facility of the Centre, collaborated with the group, and published papers on various topics such as minerals, soils, glasses, ferrites, and nanocrystalline materials.

At present, the group is working on transition metal based nanomaterials and nanocomposites prepared by sol-gel, co-precipitation, dc magnetron sputtering, and high energy ball milling. The effect of swift heavy ions on these materials is also under study.  


University of Hyderabad
Hyderabad

Names and Titles of Researchers

Prof. Chandrahas Bansal – Group Leader

Dr. S. Sarkar – Senior Research Fellow

Ajay Mishra – Junior Research Fellow

Tejal Abraham – Research Scholar

Praveen – M.Phil. Student

Description and Areas of Research

Mössbauer spectroscopy work began at the University of Hyderabad right from the very inception of the University in 1977, when Prof. Bansal joined the University faculty after completing his doctoral thesis work in this area at the Tata Institute of Fundamental Research, Bombay. The first spectrometer installed was a commercial system procured from Elscint, Israel, and this was housed in the Central Instruments Laboratory of the University to make it available to other users within the school as well users from other schools.

In 1985, a very bright student, Thampi Kumaran (now faculty at Christian College, Marthandam) joined Prof. Bansal for his Ph.D. work and built a versatile and low-cost Mössbauer spectrometer with a low dead time. This spectrometer has been functioning in the research laboratory ever since, providing very reliable and good quality data.

The focus of research using Mössbauer spectroscopic studies in the earlier years was to explore the effects of chemical, structural, and magnetic order-disorder effects in alloys. Several alloy systems, such as Fe doped Ni-Au, (Fe1-x Mx)3 Si (M = Mn, Cr, Ni), Fe-Si, Fe-Sc, Cr-Fe, Co-Fe, Ni-Fe, (Fe1-xMx)3Al, and NiFeCr, were investigated, leading to about 25 publications.

Since 1995, after working with Professor Fultz in Caltech, the group has used Mössbauer spectroscopic studies very extensively to study the effect of nanometer grain size and grain boundary regions on the phase transformation behavior of nanocrystalline alloys. They have found this technique very fruitful for these investigations and very often the unique information available from the study of hyperfine interactions in these alloy systems is not available with other measurements. For instance, using hyperfine magnetic field distributions from Mössbauer spectroscopy, they observed an interesting size effect in nanophase Fe3Ge alloys wherein the bcc structure with smaller Gibbs free energy was stabilized for small size and the equilibrium fcc phase was seen only beyond a critical crystallite size. Similarly, they have explored the kinetic paths for atomic ordering in FeCo-Mo, which were seen to lie on a universal curve at different temperatures, suggesting that the extensive grain boundary regions serve as short-circuited paths for atom movements. The precipitation phase transformation in nanocrystalline Fe-Mo and the spinodal decomposition in nanocrystalline Fe-Cr alloys also evinced interesting phase transformation behavior related to the nanosized grains in these alloys.

Currently, Ajay Mishra and Prof. Bansal are exploring nanosize effects on the oxidation behavior of nanocluster Fe films synthesized by gas phase condensation and energetic cluster impact by Mössbauer spectroscopy.

The group also collaborates with outside groups from Osmania University, the Saha Institute of Nuclear Physics, and the Indian Institute of Science–Bangalore on problems that need to use Mössbauer spectroscopy.


University of Madras
Chennai

Names of Researchers

Prof. A. Narayanasamy

Dr. K. Sivaji

Mr. B. Soundarajan

Dr. S. Amirthapandian

Mr. R. Justin Joseyphus

Mr. D. Prabhu

Mr. N. Sivakumar


Standing from the left: R. Justin Joseyphus,
D. Prabhu, N. Sivakumar, and S. Amirthapandian.
Seated: A. Narayanasamy.

Description and Areas of Research

57Fe Mössbauer effect research was started in the University of Madras in the year 1972. The work was initiated by a group of only two persons: Prof. T. Nagarajan and Mr. A. Narayanasamy. Two years later, Mr. P. M. K. Swamy joined this group. Initially a constant velocity spectrometer, fabricated with the help of the Bhabha Atomic Research Centre in Mumbai, was available. A constant acceleration spectrometer (ECIL, India) in 1975, a WissEl spectrometer in 1987, and a Nucleonix (India) spectrometer in 2002 were added to the facility. A CTI close cycle cryostat is available to cool the absorber from 300 K to 16 K.

The 57Fe Mössbauer tool is used mainly to study the hyperfine interactions in alloys and compounds, hyperfine field distributions in disordered binary alloys and in metglas, cation distributions and spin canting in spinel ferrites, the site occupancy of the substituents in permanent magnet materials like Nd2Fe14B and Sm-Co compounds, and hyperfine interactions in FINEMET and HITPERM soft magnetic alloys. The group used this technique to investigate the decomposition products in garnets in collaboration with Dr. R. Krishnan, Laboratoire de Magnetisme et d’ Optique, Versailles, France.

They also use Mössbauer spectroscopy to study the mechanochemical reactions in collaboration with Prof. K. Chattopadhyay, Department of Metallurgy, Indian Institute of Science, Bangalore, India. Combined with the EXAFS technique, the Mössbauer effect was highly useful to establish, for the first time, the Ni2+ ion occupancy in tetrahedral sites in nanostructured NiFe2O4 and an unusual cation distribution of more than eight tetrahedral sites occupied in nanostructured Ni0.5Zn0.5Fe2O4 spinel ferrite. The exciting results obtained were the establishment of ferrimagnetic ordering in nanostructured ZnFe2O4, which resolved the controversy prevailing in the literature as to whether it was ferromagnetically or ferrimagnetically ordered and the amorphous phase separation in metglas.

They collaborated with Prof. Ajay Gupta, Inter-University Consortium for the Department of Atomic Energy Facilities Indore Centre, India, for the study of ion beam mixing in Fe/Ag multilayer system using conversion electron Mössbauer spectroscopy. They found direct evidence through conversion electron Mössbauer spectroscopy for a complete mixing in Fe/Ag multilayer system. The Mössbauer study was found to be more decisive than secondary ion mass spectroscopy in this respect. This technique yielded fruitful results in determining the size of the single domain particles of CoFe2O4 in collaboration with Tohji’s laboratory in Tohoku University, Sendai, Japan.For in-field Mössbauer measurements, the group uses the facility available with Prof. J-M. Greneche, Université du Maine, Le Mans Cedex, France, and also with Prof. I. Nakatani, National Research Institute for Metals, Tsukuba, Japan.

About 20 research scholars, faculty members, and technical staff so far have contributed to the development of this technique in this University. More than 100 research articles have been published in international journals. The facility is extended to sister institutions in the country and also to collaborators abroad.


Department of Chemistry
Guru Nanak Dev University
Amritsar

Names and Titles of Researchers

Dr. B. S. Randhawa – Professor

Dr. Manpreet Kaur – Lecturer

Mr. Karun Gandotra – Research Fellow

Mr. Harmanjit Singh Dosanjh – Research Fellow

Mr. Captain Singh – M.Sc. (H.S) student

Ms. Durgesh Nandini – M.Sc. (I.A.) student

Ms. Amandeep Kaur  – M.Sc. (I.A.) student

Description and Areas of Research

Guru Nanak Dev University, established in the historic city of Amritsar on November 24, 1969, to mark the 5ooth Birth Anniversary of Sri Guru Nanak Dev, the first Sikh Guru, is striving to equip its students to face the challenges of the 21st century. To create a scientific and technological atmosphere in this region, this institution of higher learning has introduced a large number of courses in science and technology. Spread over a stretch of 500 acres on the northwest border of India, this University has done exceedingly well both in academics and sports for its 36 years of existence.

The Department of Chemistry came into existence in 1971 and over a period of time has emerged as one of the premier departments, not only of the University, but also has acquired prestigious status even at the national level. The Department offers courses of B.Sc. (Hons. School), M.Sc. (Hons. School), M.Sc. Chemistry (Instrumental Analysis), and M.Sc. (Industrial Chemistry). The research activities of the Department focus on materials chemistry, Mössbauer spectroscopy, thermal analysis, synthetic organic chemistry, inorganic chemistry, solid state chemistry, electrochemistry, chemistry of surfactants, chemistry of oils and fats, theoretical chemistry, thermodynamics, and analytical chemistry.  

The Mössbauer laboratory was established in the Chemistry Department in 1977, the credit for which goes to Dr. A. S. Brar (now professor at IIT Delhi). He headed the Mössbauer group until 1982, after which time Dr. B. S. Randhawa took over the charge of the laboratory/group. Since its inception, the laboratory has produced 10 Ph.D.-, five M.Phil.- and many M.Sc.-level dissertations. About 100 research articles involving Mössbauer spectroscopy as a major technique have been published in reputed international journals.

The tool has been employed for the identification/characterization of various intermediates/products formed during the process of thermal and photo-decomposition of metal ferricarboxylates. Coupled with other physio-chemical techniques such as XRD, TG-DTG-DSC, IR, SEM, etc., it provides an excellent stock of information in understanding the mechanism of thermolysis that leads to the obtaining of very useful magnetic materials (ferrites, the end product).

Recently, a German-made PC-based computerized Mössbauer spectrometer has been installed in the laboratory.


Materials Science Research Centre
Indian Institute of Technology Madras
Chennai

Names and Titles of Researchers

Prof. U. V. Varadaraju – Group Leader

Present Group Members (Senior Research Fellows):

Mr. M. V. V. M. Sathya Kishore
Mr. N. Lakshminarasimhan
Mr. K. Biswas
Mr. M. Anjireddy
Mr. V. Sivakumar
Mr. M. Pardha saradhi           

Group Members Involved in Mössbauer Work:

Dr. M. Sugantha
Dr. P. A. Ramakrishnan
Dr. V. Badri
Dr. M. Venkatesan
Dr. K. N. Marimuthu
Dr. T. Alamelu       

Description and Areas of Research

The group at the Indian Institute of Technology Madras is involved in the synthesis of new and novel ternary and quarternary oxides, phosphates, chalcogenides, pnictides, and intermetallic systems. The emphasis is on electronic, magnetic, thermal expansion, luminescence, and energy storage properties. The group specializes in studying structure-composition-property correlations. Mössbauer spectra have been extensively used by the group to explore the local site symmetries that play an important role in determining the physical properties.

They studied Li intercalation into phosphates (NZP based) with 3-D network structure containing Fe and established the preferential reduction of Fe3+ during intercalation and the co-existence of Fe2+ and Fe3+ superparamagnetic clusters. In addition, the Fe Mössbauer studies provided indirect evidence for the possible coexistence of Lin+ clusters in the Fe inserted phases. Fe intercalated layered selenide carbides (Nb2Se2C) are studied by Mössbauer spectroscopy, wherein the inserted Fe is shown to exist in both Fe2+ and Fe3+ states, giving rise to ferro/ferri magnetic ordering at low temperatures.

An interesting Mössbauer study has been made on the double perovskite compounds ALaFeNbO6 (A = Ca, Sr), wherein the Fe and Nb are expected to be in the formal oxidation state of Fe3+ and Nb4+. From the Mössbauer study it is established that a novel internal redox mechanism is operative in these compounds. Thus, Fe2+/Fe3+ and Nb5+/Nb4+ coexist in the lattice. Such internal redox mechanism, however, has not been observed in the hollandite phases K2Ti5NbFe2O16, wherein the Mössbauer spectra indicate the presence of only Fe3+ in the lattice.

The group has studied the Mössbauer spectra of Fe present in four inequivalent crystallographic sites in HoErFe17-xGax phases and their carbides. The variation of the weighted average hyperfine field with temperature is found to obey T2 behavior, suggesting the presence of single-particle excitation. Insertion of carbon at interstitial sites increases the hyperfine fields. Mössbauer spectra of the double perovskite Sr2FeMoO6 shows the presence of three different environments for Fe. The intensity of the minor component gives the concentration of antisite defects. The electronic structure of the iron is not exactly 3d5 because of the partial 3d(Fe) character of the ↓ electrons in the π* band made up of 3d(Fe)t2g and 4d(Mo)t2g electrons.  In the case of (Sr,Ca)2FeReO6, the isomer shift (δ) values are intermediate between high spin Fe2+ and Fe3+ in oxides. This non-integral 3d electronic configuration is probably due to the hybridization of Fe 3d (t2g) and Re 5d (t2g) states.

The Mössbauer work is done in collaboration with Prof. F. J. Berry and Dr. L. E. Smart, The Open University, Milton Keynes, U.K., and Prof. J. M. D. Coey, Trinity College, Dublin, Ireland.


Department of Chemistry
North-Eastern Hill University
Shillong

Names and Titles of Researchers

Dr. T. S. Basu Baul – Teacher-in-Charge/Group Leader

Mr. Cheerfulman Masharing – Research Fellow, Ph.D. Student)

Miss Archana Mizar – Research Fellow, Ph.D. Student)

Mr. Pradip Das – Teacher Fellow, Ph.D. Student

Mr. Keisham Surjit Singh – Research Fellow, Ph.D. Student

Mr. Wandondor Rynjah – Research Fellow, Ph.D. Student


From left to right: Cheerfulman Masharing, Archana Mizar,
Pradip Das, Tushar S. Basu Baul, Keisham Surjit Singh,
and Wandondor Rynjah.

Description and Areas of Research

There are numerous useful applications of organotin compounds, including biological (e.g., anti-tumor activity) and industrial (e.g., as catalysts) applications. The emphasis of the group’s studies in this area is synthesis and structural, and has the specific aim of delineating the factors that dictate the adoption of a particular molecular geometry in the solid state. Such a study is essential, as bibliographic surveys have revealed that in many series of the organotin compounds and, indeed, significant structural diversity, as revealed by X-ray crystallography, is found despite similarities in chemical formulae. A combination of systematic crystallographic investigations in combination with 119Sn Mössbauer spectroscopy (whenever single crystal is unavailable) has proved most potent in that definitive conclusions can be made for the system under scrutiny.

The subject of the systematic research with the aim of finding relations among the structure and static and dynamic (reactivity, catalytic, and biological activity) properties of a broad area of organotin(IV) chemistry of mainly new azo-, imine, and azo-imine ligand skeletons, including syntheses and their characterization. The research is directed to their reactions with chemically, technically, and biologically related reactants, ligand-displacement and addition reactions, reactions with a new ligand (the way and site of coordination), and to changes in the ligand newly coordinated. The focus of research in this area is to couple biologically active moiety with organotin so as to generate active compounds against certain biological disorders. Molecular structures are studied via FT-NMR (1H, 13C, 119Sn), FT-IR, 119Sn Mössbauer, electrospray ionization mass spectrometry (ESI-MS), single crystal X-ray crystallography, and others. Such techniques are being used for regular characterization, on studying their molecular transformations in a molecule itself and on molecular rearrangements, and regrouping of the ligands (migrations, fluxional behavior) of organotin complexes.

Recently, the group used the concept of the preassembly of suitably architectured precursors containing two or three tin centers to generate larger molecular units. A few organotin(IV) complexes have demonstrated exciting structural diversity and biological applications. Concurrently, they are investigating the cytotoxicity and anti-tumor activity of these organotin compounds with the aim to invoke biological responses in tumors using human tumor cell lines, viz., A498 (renal cancer), WIDR (colon cancer), M19 MEL (melanoma), IGROV (ovarian cancer), H226 (non-small cell lung cancer), and MCF-7 and EVSA-T (breast cancer) in collaboration with Dr. Dick de Vos, Pharmachemie BV, Haarlem, The Netherlands. In addition, some selected compounds have been tested for toxicity on second larval instar of the Aedes aegypti and Anopheles stephensi mosquito larvae in order to find better larvicides; these studies being carried out in collaboration with Dr. George Eng, Department of Chemistry and Physics, University of the District of Columbia, Washington, DC, USA.

More recently, the group is also pursuing the toxicity studies on sea urchin (Paracentrotus lividus and Sphaerechinus granularis) development in collaboration with Dr. Lorenzo Pellerito of Dipartimento di Chimica Inorganica e Analitica “Stanislao Cannizzaro,” Università di Palermo, Italy.

The group has well-established collaborative links with Profs. Ray J. Butcher, Department of Chemistry, Howard University, USA; Frank E. Smith, Department of Chemistry and Biochemistry, Laurentian University, Canada; Eleonora Rivarola, Dipartimento di Chimica Inorganica e Analitica “Stanislao Cannizzaro,” Università di Palermo, Italy; Antonin Lycka, Research Institute of Organic Synthesis, Czech Republic; Michal Holcapek, Department of Analytical Chemistry, University of Pardubice, Czech Republic; Anthony Linden, Institute of Organic Chemistry, University of Zurich, Switzerland; Ulli Englert, Institut für Anorganische Chemie, Technische Hochschule Aachen, Germany; Rudolph Willem and Monique Biesemans, High Resolution NMR Centre (HNMR) and Department of Polymer Science and Structural Chemistry, Vrije Universiteit Brussel (VUB), Belgium.


Department of Chemistry
Banaras Hindu University
Varanasi


From left to right: Pratibha Tripathi, Seema Pratap, N. K. Singh,
S. K. Kushawaha, and Manoj Kumar Bharty.

Names and Titles of Researchers

Prof. N. K. Singh – Professor

Dr. Seema Pratap – Lecturer

Dr. S. K. Kushawaha – Young Scientist, DST Project

Dr. Pratibha Tripathi – Research Associate, CSIR

Mr. Manoj K. Bharti – Research Scholar

Description and Areas of Research

Research on Mössbauer spectroscopy of iron complexes in the Department of Chemistry began in 1983 as a collaborative work with Dr. M. J. M. Campbell of the Department of Chemistry, Thames Polytechnic, UK (now known as the University of Greenwich). After the retirement of Dr. Campbell, Dr. M. J. K. Thomas was kind enough to extend his cooperation to the group.

The group has been working on Fe(II & III) complexes of N2-arylcarbonothioyl carbohydrazide, substituted thiosemicarbazide, and aryl-2-aroylhydrazinecarbodithioate. The Mössbauer technique has been very helpful in deciding the oxidation state of iron, its low spin or high spin nature, and the geometry of the complexes. In a few cases they have also observed the spin state equilibrium at room temperature for iron(III) systems. The group has published about 15 papers based on Mössbauer studies of complexes and have also contributed some results to the various issues of the MERDJ during the last 10 years. The research programs were funded by the Council for Scientific and Industrial Research and the Department of Science and Technology of the Ministry of Science and Technology, New Delhi, India.

 


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