Publications (7)4.34 Total impact
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Article: Effect of Ti substitution on multiferroic properties of BiMn2O5
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ABSTRACT: We present here the magnetic, dielectric, and electronic structural properties of Ti doped BiMn <sub>2</sub> O <sub>5</sub> multiferroic materials. The x-ray diffraction (XRD) studies of BiMn <sub>2-x</sub> Ti <sub>x</sub> O <sub>5</sub> (0≤x≤0.5) indicate no structural change up to x=0.5 , though the lattice parameters ( a and c ) increase with increasing value of x . Dielectric constant and magnetization data show the evolution of new dielectric anomalies at ∼120 K and weak magnetic feature at ∼86 K with the Ti substitution compared to that of undoped one. However, Ti replacement vanishes the ferroelectric transition of BiMn <sub>2</sub> O <sub>5</sub> at ∼35 K and gradually suppresses the antiferromagnetic ordering at ∼39 K . Polarization of Bi 6s<sup>2</sup> lone pair electrons is attributed to the reason behind new dielectric anomalies, whereas new weak magnetic feature at ∼86 K is attributed to strong spin-phonon coupling. X-ray absorption spectroscopy (XAS) studies on O K , Mn K , L<sub>3,2</sub> , and Ti L<sub>3,2</sub> edges of BiMn <sub>2-x</sub> Ti <sub>x</sub> O <sub>5</sub> samples along with the reference compounds have been performed and compared to bestow the exact chemical states of functioning ions. The Ti  - 09;L -edge spectra clearly indicate the substitution of Ti <sup>4+</sup> ions in all samples. XRD as well as XAS data and increase in net magnetic moment coherently indicate the replacement of Mn <sup>4+</sup> by Ti <sup>4+</sup> .Journal of Applied Physics 09/2008; · 2.17 Impact Factor -
Article: Magnetic study of Mg0.95Mn0.05Fe2O4 ferrite nanoparticles
Solid State Commun. 01/2007; -
Article: Temperature dependent Mössbauer and dielectric studies of Mg0.95Mn0.05Fe1.0Ti1.0O4
Solid State Commun. 01/2007; -
Article: Mössbauer and magnetic studies of multiferroic Mg0.95Mn0.05Fe2-2xTi2xO4 system
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ABSTRACT: A series of polycrystalline multiferroic system Mg <sub>0.95</sub> Mn <sub>0.05</sub> Fe <sub>2-2x</sub> Ti <sub>2x</sub> O <sub>4</sub> is prepared by a solid-state reaction route. The effect of Ti <sup>+4</sup> substitution in Mg <sub>0.95</sub> Mn <sub>0.05</sub> Fe <sub>2-2x</sub> Ti <sub>2x</sub> O <sub>4</sub> has been studied using x-ray diffraction (XRD), Mössbauer spectroscopy, isothermal magnetization hysteresis, temperature dependent dc susceptibility, and temperature dependent dielectric measurements. Structural transformation from cubic spinel to tetragonal has been revealed from the XRD analysis. From the analysis of Mössbauer spectra, the decrease in hyperfine field at both tetrahedral and octahedral sites has been observed as a function of the concentration of Ti <sup>+4</sup> ions, which has been explained on the basis of a supertransferred hyperfine field. The appearance of the paramagnetic doublet within the sextet is due to the interaction of the electric field gradient (EFG) with the quadrupole moment of Fe <sup>57</sup> nucleus and the decrease in magnetic interaction between Fe ions with Ti dilution. The variation in the quadrupole splitting indicates that the EFG changes with the increase in the substitution of Ti <sup>+4</sup> ions. Isothermal hysteresis loop shows the ferromagnetic behavior of Mg <sub>0.95</sub> Mn <sub>0.05</sub> Fe <sub>2-2x</sub> Ti <sub>2x</sub> O <sub>4</sub> and the saturation magnetization is decreased with the increase in the substitution of Ti <sup>+4</sup> , which is explained by the weakeni- ng of the exchange interaction in the system. The dielectric measurements of these samples exhibit ferroelectric transition depending upon the concentration of the Ti <sup>+4</sup> .Journal of Applied Physics 05/2006; · 2.17 Impact Factor -
Article: Magnetic study of Mg0. 95Mn0. 05Fe2O4 ferrite nanoparticles
Solid state communications. 141(4):203-208. -
Article: Magnetic study of Mg(0.95)Mn(0.05)Fe(2)O(4) ferrite nanoparticles
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ABSTRACT: The magnetic properties of Mg(0.95)Mn(0.05)Fe(2)O(4) ferrite samples with an average particle size of similar to 6.0 +/- 0.6 nm have been studied using X-ray diffraction, Mossbauer spectroscopy, dc magnetization and frequency dependent real chi'(T) and imaginary chi"(T) parts of ac susceptibility measurements. A magnetic transition to an ordered state is observed at about 195 K from Mossbauer measurements. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization have been recorded at low field and show the typical behavior of a small particle system. The ZFC curve displays a broad maximum at T(mean) = 195 +/- 5 K, a temperature which depends upon the distribution of particle volumes in the sample. The FC curve was nearly flat below T(mean), as compared with monotonically increasing characteristics of non-interacting superparamagnetic systems indicating the existence of strong interactions among the nanoparticles. A frequency-dependent peak observcd in chi'(T) is well described by Vogel-Fulcher law, yielding a relaxation time tau(0) = 5.8 x 10(-12) s and an interaction parameter T(0) = 195 +/- 3 K. Such values show the strong interactions and rule out the possibility of spin-glass (SG) features among the nanoparticle system. On the other hand fitting with the Neel-Brown model and the power law yields an unphysical large value of tau(0) (similar to 6 x 10(-69) and 1.2 x 10(-22) s respectively). (c) 2006 Elsevier Ltd. All rights reserved.SOLID STATE COMMUNICATIONS. 141(4):203-208. -
Article: Magnetic study of Mg0.95Mn0.05Fe2O4 ferrite nanoparticles
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ABSTRACT: The magnetic properties of Mg0.95Mn0.05Fe2O4 ferrite samples with an average particle size of ∼6.0±0.6 nm have been studied using X-ray diffraction, Mössbauer spectroscopy, dc magnetization and frequency dependent real χ′(T) and imaginary χ″(T) parts of ac susceptibility measurements. A magnetic transition to an ordered state is observed at about 195 K from Mössbauer measurements. The zero-field-cooled (ZFC) and field-cooled (FC) magnetization have been recorded at low field and show the typical behavior of a small particle system. The ZFC curve displays a broad maximum at , a temperature which depends upon the distribution of particle volumes in the sample. The FC curve was nearly flat below , as compared with monotonically increasing characteristics of non-interacting superparamagnetic systems indicating the existence of strong interactions among the nanoparticles. A frequency-dependent peak observed in χ′(T) is well described by Vogel–Fulcher law, yielding a relaxation time and an interaction parameter . Such values show the strong interactions and rule out the possibility of spin-glass (SG) features among the nanoparticle system. On the other hand fitting with the Néel–Brown model and the power law yields an unphysical large value of τ0 (∼6×10−69 and 1.2×10−22 s respectively).Solid State Communications.
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Institutions
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2006–2008
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Aligarh Muslim University
- • Department of Physics
- • Department of Applied Physics
Alīgarh, Uttar Pradesh, India
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