Indian Journal of Pure and Applied Physics

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Volume 45

Number 10

OCTOBER 2007

CODEN: IJOPAU 45 (10) 775-870

ISSN: 0019-5596

 

Applications of Mössbauer Spectroscopy—Indian Research Efforts

(This special issue is based on the papers presented at the National Symposium on Application of 57Fe Mössbauer Spectroscopy
held at Department of Physics, Jai Narain Vyas University, Jodhpur during February 6-8, 2006)

 

 

CONTENTS

 

Foreword

777

F E Wagner

 

Preface

779

H C Verma & Brajesh Pandey

 

Papers

 

Hyperfine interactions in Heusler systems

783

K Venugopalan

 

High pressure Mössbauer spectroscopy

790

Usha Chandra

 

Application of Mössbauer spectroscopy in thermal decomposition studies of some metal ferricarboxylates

795

B S Randhawa* & K Gandotra

 

Application of 57Fe Mössbauer spectroscopy to hydrometallurgy

800

S Anand & H C Verma*

 

Electronic, Mössbauer and magnetic studies of self-assembled monodispersed FePt nanoparticles

805

N S Gajbhiye

 

Mössbauer spectroscopy: An essential tool for nanoparticle magnetism in Co0.2Zn0.8Fe2O4 ferrite

810

R N Bhowmik* & R Ranganathan

 

Mössbauer study of nano-particles of spinel ferrites LixFe3-xO4

816

Subhash Chander*, M P Sharma, Anjali Krishnamurthy & Bipin K Srivastava

 

 

 

Cation distribution in the nano size aluminium substituted cobalt ferrites using Xrd, magnetic and Mössbauer spectral studies

821

Sonal Singhal*, S K Barthwal & Kailash Chandra

 

Mössbauer study of nanoparticles of Co0.4Zn0.6Fe2O4

826

S N Dolia*, Arun S Prasad, M S Dhawan, Subhash Chander & M P Sharma

 

Hyperfine fields in nano particles of Cr0.25Co0.25Zn0.5Fe2O4

830

Ram Kripal Sharma, Om Prakash Suwalka, N Lakshmi & K Venugopalan*

 

Mössbauer and magnetic studies for the coexistence of e-Fe3-xNixN and g'-Fe4-yNiyN phases in
Fe-Ni-N nanoparticles

834

N S Gajbhiye* & Sayan Bhattacharyya

 

Ferromagnetism at room temperature in ball-milled Al-1at. %Fe

839

Varkey Sebastian, Om Prakash Suwalka, N Lakshmi & K Venugopalan*

 

Magnetization and Mössbauer studies of Ni3-xCuxFe alloys in nano-crystalline state

842

M P Sharma*, B L Prashant, Anjali Krishnamurthy & Bipin K Srivastava

 

57Fe Mössbauer studies of pseudo-binary alloy system Fe1-yCrySb2 for 0 ≤ y ≤ 0.97 at 300 K

846

R K Sharma & Y K Sharma*

 

Mössbauer studies of CuFe-72% alloy

851

H C Verma

 

57Fe Mössbauer study of Ti4+-substituted Li0.5(1+x)Cr0.1Fe2.4-1.5xO4 spinels

856

M C Chhantbar, A Gismelseed, K B Modi, G J Baldha, Ali Yousif & H H Joshi*

 

FTIR and Mössbauer spectroscopy applied to the study of archaeological artefacts from Maligaimedu, Tamil Nadu, India

860

C Manoharan*, R Venkatachalapathy, S Dhanapandian & K Deenadayalan

 

 

___________

*The corresponding author has been indicated by (*) mark in case of papers with more than one author.

 

  

Foreword

 

Recoilless nuclear gamma resonance spectroscopy, more commonly known as Mössbauer spectroscopy, was discovered in 1958 by Rudolf L Mössbauer, then a German PhD student. Allowing the measurement of hyperfine interactions in solids, it quickly became an efficient tool for studying all sorts of solid materials and found many applications in solid state science. Mössbauer was awarded the Nobel Prize in 1961 for his discovery.

Nearly 50 years later, Mössbauer spectroscopy has matured but is still going strong. It is best suited for studying iron, more precisely the iron isotope 57Fe, which is present with an abundance of 2 per cent in natural iron. Owing to the abundance of iron in nature and also because of the technological importance of iron, it today finds applications in many fields of science, e.g., in metallurgy, solid state chemistry and catalysis, geochemistry and mineralogy, soil science and sedimentology.

A fine example of how Mössbauer spectroscopy can be applied is as follows: two Mössbauer spectrometers were carried by the two Mars Exploration Rovers who landed on the red planet early in 2004. These spectrometers use a scattering rather than the more common absorption technique, i.e., these detect backscattered γ rays and characteristic X-rays of iron emitted after resonance absorption of the 14.4 keV level in 57Fe. Since their arrival on Mars, these spectrometers have measured hundreds of Mössbauer spectra of the Martian soil and identified a variety of iron-containing minerals like olivine, pyroxene, hematite, magnetite, goethite, and jarosite. The occurrence of the latter two points towards a Martian environment containing liquid water at the time of their formation.

Beyond the classical Mössbauer method that uses γ rays emitted by radioactive sources, nuclear resonance scattering of synchrotron radiation has become an important tool in solid state research in the past decade. Both methods together will certainly keep up the interest in using γ rays for probing the properties of solids for many years to come.

 

 

 

Prof. F E Wagner

Physics Department

E15, Technical University of Munich

Garching, Germany


Preface

 

A number of groups in India use Mössbauer spectroscopy for their research programs. This includes physicists, chemists and material scientists. International Conference on the Application of the Mössbauer Effect 1981 was held at Jaipur, and most of the Mössbauer spectroscopists of India had assembled to attend the conference. Since then for the last 25 years, there was no such opportunity for these research groups to meet and share their achievements and plans. Research directions have significantly changed in the past decade with emergence of nanoscience and new material synthesis as prime areas. It was long felt that Mössbauer community of India should come together at a place for closer interaction and discussion so that new collaborations could be worked out and a new impact could be generated in the research.

Prof R P Tripathi, Department of Physics, Jai Narain Vyas University, Jodhpur, took the lead and arranged for all requirements to conduct such a meeting and “National Symposium on Application of 57Fe Mössbauer spectroscopy, NSAMS-06” was announced for February 6-8, 2006. Large number of researchers responded to the announcement and abstracts were sent for contributed and invited talks. The scientific committee consisting of Prof N S Gajbhiye of Department of Chemistry and Prof H C Verma of Department of Physics, IIT Kanpur, Kanpur - 208 016, thoroughly screened the abstracts and final invitations were sent to the selected researchers.

The Symposium started with the Keynote address by Prof S K Date who deliberated on the work in India since early days of Mössbauer research. Papers were presented as per schedule and discussions were made. The papers for Special issue were collected from the participants who were willing to contribute in the Special issue. A stringent process for peer review was applied. The manuscripts received were sent to reputed Mössbauer researchers across the world for review. A total number of 26 reviewers gave their services to review the papers of which 6 reviewers were from India and 20 from abroad. Based on the reviewers’s comments many of the manuscripts were revised and resubmitted. The editors looked into the modifications made and took decisions about the acceptance of the papers to go into this Special issue.

The NSAMS-06 special issue contains all the accepted paper in the category of invited talk and contributed talk and poster presentations. A total number of 6 papers were accepted in the invited talk category and 11 papers were accepted as contributed presentations. In the special issue, the invited talks appear first followed by the contributed papers.

The Special issue will serve as a reference document for the current Mössbauer related work going on in various research laboratories in India and will be a valuable resource for young researchers. Finally, we thank Mrs Poonam Bhatt for her sincere efforts and full cooperation in bringing out this special issue on Applications of Mössbauer Spectroscopy.

 

Guest Editors

 

Prof. H C Verma

Department of Physics

IIT Kanpur, Kanpur - 208 016

 

                                                                                                                                                        and

 

Dr Brajesh Pandey

Senior Research Fellow

Department of Physics

IIT Kanpur, Kanpur - 208 016

Indian Journal of Pure & Applied Physics

Vol. 45, October 2007, pp. 783-789

Hyperfine interactions in Heusler systems

 

K Venugopalan

Department of Physics, Mohanlal Sukhadia University, Udaipur 313001

E mail: venu@mlsu.org

Received 17 July 2007; accepted 2 August 2007

Recently, there has been a new surge of interest in Heusler alloys because of possible use of these alloys as materials for spin electronic devices. Heusler alloys also offer excellent systems for studying magnetic interactions. These alloys can be held at various degrees of order and also allow systematic substitution of one or more of the constituents. The magnetic and transport properties of these alloys can, therefore, be modified through such methods. Hyperfine interactions studies in a disordered Heusler system Fe2CrAl using Mössbauer spectroscopy, have been presented. The disorder present in the system is reflected in the X-ray diffraction and Mössbauer spectra. The system behaves like a normal ferromagnet even in the presence of disorders.

Keywords:   Mössbauer spectroscopy, Heusler alloys, Half-metals, Disordered alloy, Magnetic hyperfine interactions

IPC Code:   G01J3/28

 

Indian Journal of Pure & Applied Physics

Vol. 45, October 2007, pp. 790-794

High pressure Mössbauer spectroscopy

 

Usha Chandra

High Pressure Physics Lab., Department of Physics, University of Rajasthan, Jaipur 302004

Email: ushac_jp1@sancharnet.in

Received 15 February 2007; revised 17 July 2007; accepted 9 August 2007

Pressure induces myriad changes in materials by bringing order/ disorder, by changing electronic hybridization and by inducing chemical reactions. High-pressure Mössbauer spectroscopy using Diamond Anvil Cell, a well recognized tool to investigate various types of phase transitions in materials, has been studied.

Keywords: High-pressure Mössbauer spectroscopy, Phase transition, Diamond anvil cell (DAC), Mössbauer parameters

IPC Code: G01J3/28

 

Indian Journal of Pure & Applied Physics

Vol. 45, October 2007, pp. 795-799

 

 

Application of Mössbauer spectroscopy in thermal decomposition studies of some metal ferricarboxylates

 

B S Randhawa* & K Gandotra

Department of Chemistry, Guru Nanak Dev University, Amritsar143 005

Received 15 February 2007; revised 27 July 2007; accepted 10 August 2007

The thermal decomposition of magnesium and calcium hexa(formato)ferrates(III), M3[Fe(HCOO)6]2´H2O, has been carried out in flowing air atmosphere from ambient temperature to 700°C. Various physico-chemical techniques i.e. TG, DTG, DSC, XRD, IR, Mössbauer spectroscopy etc. have been employed to characterize the intermediates/end products. After dehydration, the anhydrous complexes undergo decomposition to yield an iron(II) oxalate intermediate in the temperature range 100-130°C. A subsequent oxidative decomposition of iron(II) species leads to the formation of α-Fe2O3 and respective alkaline earth metal carbonate/oxide in successive stages. Finally, nanosized ferrites of the stoichiometry, MgFe2O4 and Ca2Fe2O5 have been obtained as a result of solid-state reaction between α-Fe2O3 and a fraction of MO. The obtention of ferrites at a temperature much lower than possible in conventional ceramic method, is a special feature of the method used.

Keywords: Mössbauer spectroscopy, X-ray diffraction, Ferrites, Metal ferricarboxylates

IPC Code: G01J3/28

Indian Journal of Pure & Applied Physics

Vol. 45, October 2007, pp. 800-804

 

Application of 57Fe Mössbauer spectroscopy to hydrometallurgy

 

S Anand* & H C Verma**

* Regional Research Laboratory, Bhubaneswar 751 013, Orissa

**Physics Department, Indian Institute of Technology Kanpur, Kanpur, UP

Received 15 February 2007; revised 24 July 2007; accepted 9 August 2007

The ores and concentrates utilized for non ferrous metal extraction through hydrometallurgical processing contain iron in different forms. During processing iron gets distributed in various streams such as leach solution, leach residue and precipitated iron cake/impurities. Many secondary high iron containing materials such as iron scrap, blue dust etc. can be used to produce specific value added products such as ferrites and iron oxides. 57Fe Mössbauer spectroscopy can be applied to understand the phases of iron in such processes. The present paper gives a few examples of useful information derived from Mössbauer spectroscopy during studies on conversion of goethite to magnetite, synthesis of hematite and dissolution of Cu, Ni and Co from matte obtained by smelt-reduction of manganese nodules.

Keywords: Mössbauer spectroscopy, Hydrometallurgy, 57Fe, Goethite, Magnetite

IPC Code: G01J3/28

Indian Journal of Pure & Applied Physics

Vol. 45, October 2007, pp. 805-809

Electronic, Mössbauer and magnetic studies of self-assembled
monodispersed FePt nanoparticles

 

N S Gajbhiye

Department of Chemistry, Indian Institute of Technology, Kanpur 208 016, UP

Institute of Nanotechnology, Forschungszentrum Karlsruhe, PO Box 3640, 76021 Karlsruhe, Germany

E-mail: nsg@iitk.ac.in

Received 15 February 2007; revised 18 July 2007; accepted 6 August 2007

The organic ligand encapsulated and bare 4 nm FePt particles, synthesized by wet chemical processing are studied for their structural, electronic and magnetic properties. The fcc phase is stable even above 833 K without any agglomeration and particle growth. The Mössbauer spectra recorded at 10 K for the as-prepared and annealed FePt nanoparticles reveal the presence of superparamagnetic and ferromagnetic fractions. The superparamagnetic blocking temperature decreases from
55 K to 10 K, after annealing at 623 K, due to the decrease in magnetocrystalline anisotropy and Fe-Pt-C is formed at the surface at elevated temperatures. Two distinct sextets are observed at 10 K with a large magnetic hyperfine field for one of the components. The 2D array of the nanoparticles and also the electronic and magnetic properties of the Fe sites are retained even after removing the organic ligand molecules.

Keywords: FePt Nanoparticles, Self-assembly, Mössbauer spectra, Anisotropy, Superparamagnetism

IPC Code: B82B, G01J3/28

Indian Journal of Pure & Applied Physics

Vol. 45, October 2007, pp. 810-815

 

 

Mössbauer spectroscopy: An essential tool for nanoparticle magnetism in Co0.2Zn0.8Fe2O4 ferrite

 

R N Bhowmik* & R Ranganathan

Experimental Condensed Matter Physics Division, Saha Institute of Nuclear Physics, Calcutta 700 064

Received 15 February 2007; revised 25 July 2007; accepted14 august 2007

Magnetism in Co0.2Zn0.8Fe2O4 nanoparticles, prepared by mechanical activated process and chemical (co-precipitation) process has been reported. Experimental data showed that magnetic behaviour in mechanical activated nanoparticles (MANP) is drastically different in comparison with the nanoparticles (CPNP) prepared by chemical route. For example, MANP exhibited enhancement in both magnetization and ferrimagnetic order, whereas CPNP shows the reduction in both magnetization and magnetic order. The magnetic evolution during thermal activated grain growth process is also different for samples with smaller particle size, whereas magnetic behaviour for larger particle size is similar for both nano particles and approaching to the properties of bulk system. We have understood the co-existence of various competitive effects during grain growth process employing Mössbauer spectroscopy, dc magnetization and ac susceptibility measurements.

Keywords: Mössbauer spectroscopy, Nanoparticle magnetism, Co0.2Zn0.8Fe2O4 ferrite

IPC Code: G01J3/28, H01F41/30

Indian Journal of Pure & Applied Physics

Vol. 45, October 2007, pp. 816-820

Mössbauer study of nano-particles of spinel ferrites LixFe3-xO4

Subhash Chander*, M P Sharma, Anjali Krishnamurthy & Bipin K Srivastava

Department of Physics, University of Rajasthan, Jaipur 302 004

*Present address: Department of Physics, Sobhasaria Engineering College, Sikar 332 001

Received 15 February 2007; revised 31 July 2007; accepted 3 August 2007

Mössbauer spectra have been recorded on three nano-particle samples in the series LixFe3-xO4 (for x = 0.1, 0.2 and 0.3) at 300K and 80K. Spectra could be resolved into two doublets attributed to two crystalline sites, viz., tetrahedral site and octahedral site. Li occupies the octahedral site with a complete preference as in the bulk particle size state. Analysis of Mössbauer spectra shows that electron hopping manifests at temperatures down to 80K implying the absence of a Verwey type transition. Magnetization measurements support this inference and are suggestive of no such transition occurring down to 20K.

Keywords: Mössbauer study, Nano-particles, Spinel ferrites, LixFe3-xO4

IPC Code: G01J3/28, H01F41/30

 

Indian Journal of Pure & Applied Physics

Vol. 45, October 2007, pp. 821-825

Cation distribution in the nano size aluminium substituted cobalt ferrites using Xrd, magnetic and Mössbauer spectral studies

Sonal Singhal1, S K Barthwal2 & Kailash Chandra3

1Department of Chemistry, Panjab University, Chandigarh,

2Department of Physics, 3Institute Instrumentation Centre, Indian Institute of Technology-Roorkee, Roorkee 247 667

3E-mail: chandfuc@iitr.ernet.in

Received 15 February 2007 ; revised 19 July 2007 ; accepted 17 August 2007

Aerosol route have been used to prepare the nano size ferrites CoFe2O4, CoAl0.37Fe1.63O4, CoAl0.95Fe1.05O4 and CoAl1.36Fe0.64O4. A decrease in lattice parameter and saturation magnetization with the increase of aluminium concentration was attributed to the smaller ionic radius and weakening of exchange interactions respectively. Room temperature Mössbauer spectra of as obtained samples exhibited a broad doublet suggesting super paramagnetic nature. The samples annealed at 1200oC showed broad sextets, which were fitted with different sextets, due to the tetrahedrally and octahedrally coordinated iron cation. The cation distribution calculated from the X-ray intensity and Mössbauer data indicated that Al3+ ions enter into A and B sites in ~2 : 3 ratio and Fe3+(oct.)/Fe3+(tet.) ratio increases with Al3+ concentration.

Keywords: Cobalt ferrites, Nano size aluminium, Mössbauer spectral studies, Aerosol

IPC Code: B82B, G01J3/28

Indian Journal of Pure & Applied Physics

Vol. 45, October 2007, pp. 826-829

 

Mössbauer study of nanoparticles of Co0.4Zn0.6Fe2O4

 

S N Dolia*, Arun S Prasad, M S Dhawan, Subhash Chander# & M P Sharma

Department of Physics, Unfiversity of Rajasthan, Jaipur 302 004

#Present address: Sobhasaria Engineering College, Sikar

*E-mail: sndolia@uniraj.ernet.in

Received 15 February 2007; revised 17 July 2007; accepted 2 August 2007

Two samples of nanoparticles of Co0.4Zn0.6Fe2O4 with the average particle sizes of 6 nm and 15 nm have been synthesized by chemical co-precipitation method and followed by heat treatment at 6000C. The cubic spinel structure in single phase has been confirmed by X-ray diffraction. The lattice parameters are 8.39 Å and 8.41 Å, respectively. 57Fe Mössbauer spectra were recorded at 300 K and 80 K. Both samples are resolved in two patterns corresponding to two crystalline sites. The Mössbauer spectra and hysteresis curves for the two samples recorded at 300 K show superparamagnetic behaviour. The analysis of Mössbauer spectra reveal that the intensity of Fe3+ ions on both sites is nearly the same which indicate that the Zn2+ occupies the octahedral site in these samples.

Keywords:   Nano-particles, Spinel ferrite, Mössbauer spectra

IPC Code:       G01J3/28, H01F41/30

Indian Journal of Pure & Applied Physics

Vol. 45, October 2007, pp. 830-833

 

Hyperfine fields in nano particles of Cr0.25Co0.25Zn0.5Fe2O4

 

Ram Kripal Sharma, Om Prakash Suwalka, N Lakshmi* & K Venugopalan

Department of Physics, Mohanlal Sukhadia University, Udaipur 313001

Received 15 Februaary 2007; revised 26 July 2007; accepted 8 August 2007

Nano particles of Cr substituted cobalt zinc ferrite (Cr0.25Co0.25Zn0.5Fe2O4) were synthesized using chemical co-precipitation technique. Particles of average crystallite sizes varying from 5 to 23 nm were obtained by controlling the annealing temperature during preparation. Fe-57 Mössbauer studies at room temperature showed that samples with particle sizes smaller than 10nm were superparamagnetic while those with bigger particle sizes showed the co-existence of a ferrimagnetic phase with a superparamagnetic one. Mössbauer spectra recorded at 25 K for the smallest sized sample showed well defined sextets with hyperfine fields of 520 kOe and 484 kOe corresponding to the A and B sites.

Keywords: Nanoparticles, Fe-57 Mössbauer spectroscopy, Superparamagnetism

IPC Code: B82B, G01J3/28

Indian Journal of Pure & Applied Physics

Vol. 45, October 2007, pp. 834-838

Mössbauer and magnetic studies for the coexistence of e-Fe3-xNixN and
g'-Fe4-yNiyN phases in Fe-Ni-N nanoparticles

N S Gajbhiye1,2 & Sayan Bhattacharyya1

1Department of Chemistry, Indian Institute of Technology, Kanpur 208 016

2Institute of Nanotechnology, Forschungszentrum Karlsruhe, P.O. Box 3640, 76021 Karlsruhe, Germany
2E-mail: nsg@iitk.ac.in

Received 15 February 2007; revised 26 July 2007; accepted 2 August 2007

Nanocrystalline e-Fe3-xNixN (x = 0.5-0.8) particles are synthesized by precursor technique and nitridation of decomposed products in NH3 (g) at 673 K. A small fraction of fcc g'-Fe4-yNiyN phase (space group: P43m) is precipitated along with the formation of e-Fe3-xNixN hexagonal structure (space group: P63/mmc). The Mössbauer spectrum at room temperature for all the compositions shows the presence of superparamagnetic doublet, which is attributed to e-Fe3-xNixN phase and two sextets corresponding to the corner Fe (Fec) and fcc Fe (Fef), in g'-Fe4-yNiyN. The added Ni atoms preferentially substitute the Fec positions. The isomer shift, quadrupole splitting and hyperfine field values vary with the Ni content. The zero-field cooled (ZFC) and field-cooled (FC) curves indicate strong interparticle interactions and surface spin-glass-like state is realized from the low temperature features. The magnetization curves are saturated at 5 K, due to the dominating ferromagnetic nature of the g'-Fe4-yNiyN phase.

Keywords: Nanoparticle, Iron-nickel nitride, Mössbauer, Spin canting, Superparamagnetism

IPC Code: B82B, G01J3/28

Indian Journal of Pure & Applied Physics

Vol. 45, October 2007, pp. 839-841

Ferromagnetism at room temperature in ball-milled Al-1at.%Fe

Varkey Sebastian, Om Prakash Suwalka, N Lakshmi* & K Venugopalan

Department of Physics, M L Sukhadia University, Udaipur 313 001, Rajasthan

*E-mail: nambakkat@yahoo.com

Received 15 February 2007; accepted 4 August 2007

Iron nano particles have been embedded in an aluminium matrix through high energy ball milling. The Mössbauer spectrum of the as-milled sample at room temperature shows the presence of a magnetic hyperfine sextet, a paramagnetic singlet and a quadrupole doublet with relative areas of nearly 78, 16 and 6%, respectively. The value of the hyperfine field for the sextet corresponds to that of α-Fe. The quadrupole component, which is indicative of formation of an Al-rich solid solution, is broad with a width of 0.73 mm/s indicating a distribution in the quadrupole fields. The value of the average splitting is 0.5mm/s and isomer shift (IS) equal to 0.49mm/s with respect to metallic iron. M-H measurements show that the unmilled system is non-magnetic while the milled system of 30 min is ferromagnetic and exhibits very soft magnetic properties. Unreacted Fe clusters embedded at the nano-crystalline Al grain boundaries seem to be responsible for the observed net magnetic moment.

Keywords: Ball-milling, Fe-57 Mössbauer spectroscopy, Quadrupole field distribution

IPC Code:G01J3/28, H01F41/30

Indian Journal of Pure & Applied Physics

Vol. 45, October 2007, pp. 842-845

 

Magnetization and Mössbauer studies of Ni3-xCuxFe alloys in nano-crystalline state

M P Sharma, B L Prashant, Anjali Krishnamurthy & Bipin K Srivastava

Department of Physics, University of Rajasthan, Jaipur 302 004

Received 15 Februaary 2007 ; revised 20 July 2007 ; accepted13 August 2007

The iron-nickel alloys, commonly known as permalloys, known for atomic disorder, have been studied due to their interesting magnetic properties. Nano-particle samples have been prepared for three compositions in the series
Ni3-xCuxFe.57Fe Mössbauer studies are reported on the three nano-particle samples which are found to be ferromagnetic. The value of Tc goes down from 880K in Ni3Fe to 800K in Ni2CuFe. The introduction of Cu causes the saturation moment to decrease and lowering of temperature cause an increase in atomic disorder.

Keywords: Mössbauer spectra, Nanoparticles, Ni3-xCuxFe alloys, Ferromagnetic

IPC Code: G01J3/28, H01F 41/30

Indian Journal of Pure & Applied Physics

Vol. 45, October 2007, pp. 846-850

57Fe Mössbauer studies of pseudo-binary alloy system
Fe1-yCrySb2 for 0 ≤ y ≤ 0.97 at 300 K

R K Sharma & Y K Sharma*

Department of Physics, University of Rajasthan, Jaipur 302 004

*E-mail: yksharma@uniraj.ernet.in

Received 15 February 2007; revised 30 July 2007; accepted 20 August 2007

57Fe Mössbauer and X – ray powder diffraction (XRD) of the alloy system Fe1-yCrySb2 for 0 ≤ y ≤ 0.97 at 300K have been studied. XRD patterns of all specimens recorded using FeKα radiation at 300K suggest the presence of single phase orthorhombic crystal structure for this alloy series. The lattice parameters and the unit cell volume increase with the increase in chromium concentration. The 57Fe Mössbauer spectra for all the compositions analyzed as a single quadrupole split doublet reveal the paramagnetic character. The increase in the isomer shift and the decrease in the quadrupole splitting with the increase in chromium concentration y for the alloy series have been correlated with the observed structural and bonding properties of the series compositions.

Keywords: Mössbauer spectroscopy, Fe1-yCrySb2 alloys, Paramagnetism, X-ray diffraction

IPC Code: B82B, G01J3/28

 

Indian Journal of pure & Applied Physics

Vol. 45, October 2006, pp. 851-855

 

 

Mössbauer studies of CuFe-72% alloy

H C Verma

Department of Physics, Indian Institute of Technology Kanpur, Kanpur 208 016

E-mail: hcverma@iitk.ac.in

Received 15 February 2007; revised 24 July 2007; accepted 7 August 2007

Cu-Fe alloy with 72 at % of iron in powder form is prepared using simultaneous electrodeposition from a common electrolytic bath. Mössbauer spectra of the as-prepared sample show a superposition of quadrupole doublet with a large line broadening and a small component of a six line Mössbauer spectrum which has been characterized to be pure iron phase. As the samples are annealed, more and more segregation of magnetic part takes place. The linewidth and the quadrupole splitting of the residual doublet change in a correlated fashion and go through a maximum at 300°C. The crucial factor responsible for line broadening seems to be defect distribution and oxygen/hydrogen incorporation during electrodeposition and alloying. The phase-segregated iron on heating is in oxidized form (hematite and magnetite) most probably due to reaction with oxygen incorporated at the time of deposition.

Keywords: Mössbauer study, Cu-Fe-alloy, Quadrupole splitting, Mössbauer spectrum

IPC Code:G01J3/28

 

Indian Journal of Pure & Applied Physics

Vol. 45, October 2007, pp. 856-859

 

 

57Fe Mössbauer study of Ti4+-substituted Li0.5(1+x)Cr0.1Fe2.4-1.5xO4 spinels

M C Chhantbar, A Gismelseed*, K B Modi, G J Baldha, Ali Yousif* & H H Joshi

Department of Physics, Saurashtra University, Rajkot 360 005

*Department of Physics, Sultan Qaboos University, Muscat, Oman

Received 15 February 2007; revised 23 July 2007; accepted 14 August 2007

57Fe Mössbauer effect (ME) was studied at 295K and 77K on the polycrystalline samples of the spinel oxide system Li0.5(1+x)Cr0.1Fe2.4-1.5xO4 (x = 0.0 to 0.5) synthesized by double sintering ceramic technique. The chemical stoichiometry of the final products was ascertained by EDAX. The X-ray diffractometry (XRD) showed that all the samples were single-phase cubic spinels. The cell edge parameter, a (Å) for each composition was found by XRD-pattern indexing and using the Nelson-Riley method. The distribution of cations in the spinel was determined through XRD intensity analysis using the computer programme. The saturation magnetization for each composition was recorded using hysteresis loop tracer at the applied field of 4kOe. The Mössbauer spectra exhibit two Zeeman sextets due to different fields at tetrahedral (A) and octahedral (B) Fe3+ ions. The ME parameters are deduced using the NORMOS software and the observed hyperfine interaction parameters are explained in the light of cation distribution determined through XRD, magnetization and Mössbauer spectroscopic studies.

Keywords: Ferrites, Magnetic properties, Mössbauer spectroscopy

IPC Code: B82B, G01J3/28

 

Indian Journal of Pure & Applied Physics

Vol. 45, October 2007, pp. 860-865

 

FTIR and Mössbauer spectroscopy applied to study of archaeological artefacts from Maligaimedu, Tamil Nadu, India

 

C Manoharan, R Venkatachalapathy*, S Dhanapandian & K Deenadayalan

Department of Physics, Annamalai University, Annamalainagar 608 002, Tamil Nadu

*Department of Physics (DDE), Annamalai University, Annamalainagar, Tamil Nadu

Received 15 February 2007; revised 25 July 2007; accepted 7 August 2007

Archaeological potteries belonging to 300 BC collected from Maligaimedu (11°48’Lat.N; 79°35’Long.E) Tamil Nadu, India were subjected to FTIR, XRD and Mössbauer spectroscopic studies in order to characterise the clay minerals associated, their origin and technology of firing adopted by artisans. To determine the firing temperature of the potteries and to find any phase change in magnetic minerals, the pottery samples were refired to different temperatures. From FTIR studies, it is observed that these pottery samples were made up of disordered kaolinite type clay with appreciable amount of iron with a firing temperature of about 800°C. The minerals like quartz, anorthite, orthoclase and hematite were identified using XRD. No change in the Mössbauer parameters are observed in the case of sample MGM-2 during laboratory firing up to 800°C, which indicates that original firing temperature is above 800°C. Changes in the Mössbauer spectra of sample MGM-5 during laboratory firing reveal that the laboratory firing atmosphere differs from original firing atmosphere. The presence of Fe2+ ion in as-received state spectra of black pottery (MGM-5) indicates that the sample was fired under reduced atmospheric condition during manufacturing. The colour of the potteries also reflects the above results.

Keywords: FTIR, Mössbauer spectroscopy, Archaeological potteries, Firing temperature

IPC Code: G01J3/28