Publications (5) View all
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Article: Magnetic and (57)Fe Mössbauer study of magneto-electric GaFeO(3) prepared by the sol-gel route.
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ABSTRACT: This work reports the preparation of magneto-electric GaFeO(3) by the sol-gel route and its characterization by x-ray diffraction, dc-magnetization, ac-susceptibility, low temperature and high field (57)Fe Mössbauer spectroscopy and dielectric constant measurements. The prepared samples are found to be single phase from x-ray diffraction studies. The crystallite sizes are found to be in the nano-regime for the samples sintered at low temperatures. From the temperature dependent dc-magnetization (M-T) measurements, bifurcation of the zero-field cooled (ZFC)-field cooled data and a cusp in the ZFC data are observed. With the help of low-field ac-susceptibility, (57)Fe Mössbauer and detailed dc-magnetic measurements these features are explained in terms of the magnetic anisotropy of the sample ruling out phenomena like spin-glass and super-paramagnetism as quoted in the literature for this compound. Apart from this, very interesting and different M-H behavior mimicking composite two-phase magnets is observed for the samples sintered at different temperatures. A symmetric M-H loop is observed for samples sintered at low temperatures and a pinched M-H loop is observed for samples sintered at high temperatures. The observed magnetic properties are explained by estimating the Fe cation distribution using high field (57)Fe Mössbauer spectroscopy measurements. An anomaly in the dielectric constant data at the Curie temperature indicates the ME coupling of the samples.Journal of Physics Condensed Matter 01/2013; 25(7):076002. · 2.55 Impact Factor -
Article: Study of Aging & De-Aging Behaviour in Un-Doped Polycrystalline Ferroelectric BaTiO 3
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ABSTRACT: Aging and de-aging behavior of un-doped polycrystalline BaTiO 3 (BTO) is studied with the P-E measurements. The double hysteresis (P-E) loop is observed for the aged sample and it is observed that the relationship between the aging time and the developed internal bias field is similar to as that of reported for acceptor doped BTO and other ferroelectric materials in literature. However, the relaxation rates are quite different as compared to that of acceptor doped BTO. This is explained in terms of defect concentration. The de-aging behaviour is studied with different methods viz., thermal relaxation, combined use of temperature and applied electric field. Heating the sample slightly above its T C and cooling in the presence of external applied dc-field is observed to completely remove the pinching and bring the internal bias field to zero.Ferroelectrics 12/2012; 437:1-171. · 0.39 Impact Factor -
Article: Anomalous variation of the Lamb-Mössbauer factor at the magnetic transition temperature in magnetoelectric GaFeO3.
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ABSTRACT: Temperature-dependent (57)Fe Mössbauer spectroscopy (5-723 K) and neutron diffraction (2-290 K) measurements are carried out on polycrystalline magnetoelectric GaFeO(3). From the neutron diffraction data, evidence for the magnetostriction and increased disorder at Fe sites close to the ferrimagnetic Curie transition temperature (T(C)) is observed. From the Mössbauer data, it is observed that the Lamb-Mössbauer factor as a function of temperature f(T), which is related to the integral over the first Brillouin zone of the phonon spectrum, shows a unequivocal variation at the T(C). The observations are discussed in terms of spin-phonon coupling. The observed average hyperfine fields from (57)Fe Mössbauer spectra match with the bulk magnetization data. A critical exponent (β) of 0.38 ± 0.02 and a Debye temperature (θ(D)) of ~350 K is estimated from the (57)Fe Mössbauer data.Journal of Physics Condensed Matter 08/2012; 24(37):376001. · 2.55 Impact Factor -
Article: Clavicle Hook Plate for Neer Type II Lateral Clavicle Fractures.
Journal of orthopaedic trauma 03/2011; 25(3):e30. · 1.78 Impact Factor -
Article: Low temperature Raman and high field 57Fe Mossbauer study of polycrystalline GaFeO3.
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ABSTRACT: The magnetic and phonon properties of polycrystalline magnetoelectric/multiferroic GaFeO(3) are studied. Using high field (57)Fe Mossbauer spectroscopy, occupation of Fe is observed at four cation sites. A Fe population of about 6% is observed at the tetrahedral Ga1 site, which explains the observed pinched-like M-H curve and initial sharp increase of the magnetization. The calculated net magnetization value from Mossbauer data suggests that the Fe moment at the Ga1 site is parallel to Fe1 and opposite to that of Fe2 and Ga2 sites, resulting in ferrimagnetism. From low temperature Raman data, anomalous temperature variation in frequency at T(C) is observed for the mode at ∼700 cm(-1).Journal of Physics Condensed Matter 04/2010; 22(14):146005. · 2.55 Impact Factor
