Mechanical losses and dielectric properties in ferroelectric-ferromagnetic composites

Abstract

The work presents the technology and investigation results of ferroelectric-ferromagnetic composites based on ferroelectric powders of the PZT type and ferrite. The ferroelectric powder comprised two PZT type compositions: Pb0.84Ba0.16(Zr0.54Ti0.46)O3 + 1.0%at. Nb2O5 (PBZTN) and Pb(Zr0.51Ti0.49)O3 + 0.2%at. Bi2O3 + 0.03%at. Nb2O5 + 0.06%at. MnO2 (PZTBNM). The initial constituents for obtaining the PZT type powders included oxides: PbO, ZrO2, TiO2, Nb2O5, Cr2O3 as well as carbonates: barium BaCO3 and strontium SrCO3. In the PZT-ferrite composites, the synthesized ferroelectric powder constituted 90%, whereas the ferrite powder (Ni0.64Zn0.36Fe2O4) was 10%. Temperature examinations of the internal friction (IF) of the PZT-ferrite type composites, which belong to nondestructive methods of material examination in mechanical spectrometry, and also measurements of the dielectric properties were performed. The IF method enabled the authors to determine mechanical properties such as mechanical losses or value of Young's modulus in a broad range of temperatures. For both the investigated composites, an increase in mechanical losses Q–1 and decrease in Young's modulus Y with an increase in temperature were observed. At the phase transition point connected with an electric sub-system change while changing from the ferroelectric to paraelectric state, a rapid increase in Young's modulus Ywas observed. It was confirmed in further investigations of dielectric properties ε(T) i tanδ (T).