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Investigation on multiferroic properties of BiFeO3 ceramics

Shariq M., Kaur D., Chandel V. S., Siddiqui M. A.

Materials Science Poland

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2013

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Vol. 31, No. 3

471--475

EN

BiFeO3 polycrystalline ceramics was prepared by solid-state reaction method and its structural, optical and magnetic properties were investigated. BiFeO3 was synthesized in a wide range of temperature (825 – 880 °C) and a well crystalline phase was obtained at a sintering temperature of 870 °C. X-ray diffraction patterns of the samples were recorded and analyzed for the confirmation of crystal structure and the determination of the lattice parameters. The average grain size of the samples was found to be between 1 – 2 μm. The determined value of direct bandgap of BiFeO3 ceramics was found to be 2.72 eV. The linear behavior of M-H curve at room temperature confirmed antiferromagetic properties of the BiFeO3 (BFO). S shaped M-H curve was obtained at a temperature of 5 K. In the whole temperature measurement range (5 – 300 K) of M-T, no anomalies were observed due to high Curie temperature and Neel temperature of the BiFeO3.

2

Low frequency dielectric relaxation and optical behaviour of a nematic liquid crystal 4-methyl n (2'-hydroxy, 4'-n-hexadecyloxy) azobenzene

Chandel V. S., Manohar S., Shukla J. P., Manohar R., Prajapati A. K.

Materials Science Poland

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2012

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Vol. 30, No. 3

290--296

EN

Low frequency dielectric relaxation has been reported for a nematic liquid crystal in the frequency range of 1 kHz to 10 MHz and in the temperature range from 25 °C to 100 °C. The optical behaviour has also been studied by measuring the refractive indices, birefringence and optical transmittance in the temperature range mentioned above. The birefringence data have been used to calculate the order parameter by Vuks' approach, and its variation with temperature has been discussed. Transition temperatures obtained using different techniques are found to be in good agreement with each other.

3

The effect of paramagnetic doping on the dielectric response of K1.85Na0.15Ti4O9 layered ceramics

Vikram S. V., Maurya D., Chandel V. S.

Materials Science Poland

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2009

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Vol. 27, No. 1

191--199

EN

Ceramic samples of layered polycrystalline (K1.85Na0.15)Ti4O9:xCu (0 ? x ? 0.8) have been prepared using high temperature solid state reaction. Room temperature X-ray diffratograms confirm the phase evolution. Room temperature electron paramagnetic resonance (EPR) data show that Cu2+occupies Ti4+ lattice sites giving rise to electric dipoles which increases electric permittivity. The absorption peak in EPR spectra gets broadened due to increased exchange interaction in heavily doped derivatives. Dielectric data reveal that occupancy of Cu2+ on Ti4+ leads to a decrease in dielectric losses and an increase in the electric permittivity as well.