Low temperature coefficient dielectric materials, PbRETiTaO₇(RE=Y, La, Nd, Sm, Gd, or Dy) having pyrochlore type structure

Abstract

The present work investigates the dielectric properties of pyrochlore type oxides, PbRETiTaO 7 (RE5Y, La, Nd, Sm, Gd, or Dy) in the low frequency region (100 kHZ-1 MHz) at temperatures between 30 and 100uC and the microwave frequency region. The 1 MHz dielectric constants (K) are in the range 43-99 and show somewhat low variation with temperature (30-100uC) as well as frequency (1 kHz to 1 MHz). The temperature coefficient of dielectric constant (TCK) over the temperature range 30-100uC is negative and varies in the range, 272 to 2342 ppm uC 21 . The dielectric constant in the microwave frequency region is in the range 23-43. Among the samples, PbGdTiTaO 7 shows very good quality factor (Q6f) of 4008 in the microwave frequency region. They all have cubic pyrochlore type structure as indicated by powder X-ray diffraction patterns. The sintered microstructure shows well formed grains without much porosity.

Glycine–nitrate synthesis of Sr doped La2Zr2O7pyrochlore powder

“…Oxides with A 2 B 2 O 7 (pyrochlore) structures have received significant attention as materials for use in power generation, heating elements, oxygen electrodes, solid electrolytes for solid oxide fuel cells (SOFCs), thermal barrier coating and for multiple electronic applications. [1][2][3][4][5][6] In SOFC applications, the lanthanum zirconate pyrochlore structure, La 2 Zr 2 O 7 (LZO), draws attention due to its ability to form an intermediate layer between La y-x Sr y MnO 3 porous cathode and Y 2 O 3 stabilised ZrO 2 dense electrolyte in SOFCs during operation. 7 The formation of the LZO layer, which can occur during high cell fabrication temperatures (about .1400uC) or operation (about 1000uC), is reported to be responsible for the degraded performance of SOFCs.…”