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

CaSn 1- x Ti x GeO 5 (0 ≤ x ≤ 1.0) ceramics were prepared using traditional solid-state reaction with sintering at 1275 °C – 1500 °C for 5 h. The Ti 4+ substitution for Sn 4+ inhibited the CaSnO 3 second phase of CaSnGeO 5 ceramic, and phase transition from triclinic with A 1 ¯ space group to monoclinic with A 2/ a space group and then to monoclinic with P 2 1 /a space group occurred in CaSn 1- x Ti x GeO 5 (0 ≤ x ≤ 1.0) ceramics. Evident changes in Sn/TiO 6 octahedron and Sn/TiO 6 octahedral chains were observed. A change in τ f 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 τ ε for CaSn 1- x Ti x GeO 5 (0 ≤ x ≤ 0.8) ceramics. The broadening and shifting of ε r anomaly peaks for CaSn 1- x Ti x GeO 5 (0.8 ≤ x ≤ 1.0) ceramics greatly influenced τ ε , and the sudden increase in τ ε was attributed to the shift of ε r anomaly peaks to high temperature.