Preparation, structure and dielectric properties of tungsten bronze ferroelectrics in SrO-Eu2O3-TiO2-Nb2O5 system

Abstract

Compounds Sr 4 Eu 2 Ti 4 Nb 6 O 30 and Sr 5 EuTi 3 Nb 7 O 30 with filled tetragonal tungsten bronze structure were prepared, and the dielectric characteristics and ferroelectric transition were investigated. Both ceramics displayed weak frequency dependence in room temperature dielectric constant, which decreased from 125 to 118 for Sr 4 Eu 2 Ti 4 Nb 6 O 30 , from 206 to 195 for Sr 5 EuTi 3 Nb 7 O 30 in the frequency range of 10 kHz to 1 MHz. The present ceramics showed a diffuse ferroelectric phase transition. The frequency independent transition temperature (T m ) indicated the above compounds had no relaxor property. The diffuseness (γ) was 1.45 and 1.64 for Sr 4 Eu 2 Ti 4 Nb 6 O 30 and Sr 5 EuTi 3 Nb 7 O 30 respectively. The weak ferroelectric of the present materials are indicated from the P-E hysteresis loops, and a small 2P r of 0.596 µC/cm 2 and 0.068 µC/cm 2