Phase transition and permittivity stability against temperature of CaSn1-xTixGeO5 ceramics

Abstract CaSn1-xTixGeO5 (0 ≤ x ≤ 1.0) ceramics were prepared using traditional solid-state reaction with sintering at 1275 °C – 1500 °C for 5 h. The Ti4+ substitution for Sn4+ inhibited the CaSnO3 second phase of CaSnGeO5 ceramic, and phase transition from triclinic with A 1 ¯ space group to monoclinic with A2/a space group and then to monoclinic with P21/a space group occurred in CaSn1-xTixGeO5 (0 ≤ x ≤ 1.0) ceramics. Evident changes in Sn/TiO6 octahedron and Sn/TiO6 octahedral chains were observed. A change in τf from negative (‒62.9 ppm/°C) to positive (+18.7 ppm/°C) was achieved by controlling octahedral distortion. The large octahedral distortion contributed to near-zero τe for CaSn1-xTixGeO5 (0 ≤ x ≤ 0.8) ceramics. The broadening and shifting of er anomaly peaks for CaSn1-xTixGeO5 (0.8 ≤ x ≤ 1.0) ceramics greatly influenced τe, and the sudden increase in τe was attributed to the shift of er anomaly peaks to high temperature.