Effect of Temperature on the Elastic and Anelastic Behaviour of Magneto-Ferroelectric Composites Ba0.8Pb0.2TiO3 + Ni0.93Co0.02Mn0.05Fe1.95O4-δ in the Ferroelectric Rich Region

Composites with composition xBa0.8Pb0.2TiO3+ (1 −x) Ni0.93Co0.02Mn0.05Fe1.95O4-δ in which x varies as 1.0, 0.9, 0.7 and 0.5 in molar percent have been prepared by the conventional ceramic double sintering process. The presence of the two phases has been confirmed by X-ray diffraction. These composites were prepared for their use as magnetoferrolectric devices. Variation of longitudinal modulus (L) and internal friction loss (Q −1) of these samples with temperature at 142 kHz has been studied in the wide temperature range 300 to 630 K. The elastic behaviour (L) showed a break at the ferroelectric Curie temperature (498 K) in the case of pure ferroelectric material (Ba0.8Pb0.2TiO3). This break shifted to lower temperature side as the ferrite component increases in the composite. The temperature variation of internal friction loss (Q −1) showed a corresponding stress induced relaxation peak at the ferroelectric-non-ferroelectric phase transition. This behaviour is explained in the light of structural phase transition.