K. K. Patankar

Structural, dielectric and transport properties of Pb(Mno.5Wo.5)O3

Polycrystalline Pb(Mn0.5W0.5)O3, a ferroelectric oxide having perovskite structure, was prepared by high temperature solid state reaction technique. Preliminary X-ray diffraction analysis confirms single phase formation with the lattice parametersa = 7.2501 Å,b = 8.1276 Å andc = 12.0232 Å. Room temperature dielectric constant (ε′) and loss tangent (tan δ) were scanned with respect to frequency in the range 100 Hz-1 MHz. Detailed study of dielectric constant and electrical conductivity reveals a phase change around 400 K, which is quite different from those in the other materials of the same type. Further, the seebeck coefficient (α) is temperature independent. The conduction is interpreted as due to small polaron hopping.

Electrical Conduction and Magnetoelectric Effect in Cu0.4Co0.6Fe2O4−Ba0.8Pb0.2TiO3 ME Composites

Magnetoelectric composites viz. Cu 0.4 Co 0.6 Fe 2 O 4 −Ba 0.8 Pb 0.2 TiO 3 were prepared using high temperature solid-state reaction technique. The presence of ferrite phase and ferroelectric phase in the composites was confirmed by XRD technique. The variation of dielectric constant with frequency and temperature indicates that the composites exhibit diffused type phase transition. The results of ac conductivity and dc resistivity show that the conduction occurs by hopping of charge carriers. The magnetoelectric (ME) effect has been studied as a function of intensity of the magnetic field. The maximum value of (dE/dH) viz. 110 μV/cm/Oe is found in case of 15% ferrite + 85% ferroelectric sample.

Impedance Spectroscopic Analysis of Bi1 - xNdxFeO3

Materials having magnetism and ferroelectricity are found to be the subject of enormous importance. Bi 1−x Nd x FeO 3 belongs to the class of materials known as ‘magnetoelectrics.’ In such materials magnetic and electric ordering is present simultaneously. Due to presence of magnetic and ferroelectric properties simultaneously these materials are found to of potential application. BiFeO3, one of the end members of the series, is mysterious material, however found to be potential material due to its distinguishable properties. The samples of Bi 1− x Nd x FeO 3 have been prepared by solid state reaction technique, characterized by X-ray diffraction technique and dielectric properties of the samples have been studied. Impedance spectroscopy is known as versatile tool to understand various contributions to dielectric measurements. In the present investigation, we have used the tool of impedance spectroscopy and experimental data has been fitted using suitable electronic circuit with circuit elements of different values. Agreement between experimental and simulated data is established by assuming a frequency dependent capacitive element. The complex impedance indicates that the samples prepared can be represented by two layer leaky capacitor which corresponds to the bulk and grain boundary phenomena at high and low frequencies.