Low‐temperature dielectric behavior of Sc‐ and In‐doped bismuth titanate pyrochlores

• Published in: Journal of the American Ceramic Society 2022-02, Vol.105 (2), p.1173-1184
• Main Authors: Krasnov, Aleksei G., Sakhatskii, Aleksandr S., Piir, Irina V.
• Format: Article
• Language: English
• Subjects: Bismuth titanate; bismuth titanates; dielectric; Dielectric loss; Dopants; dopants/doping; LTCC; materials/properties; pyrochlore; Pyrochlores; Room temperature
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/jace.18146

The detailed structural description and analysis of dielectric behavior of Bi1.6MxTi2O7‐δ (M – Sc, In; x = 0.2, 0.4, 0.6) compositions are demonstrated. Doping results in cation disorder either in A‐site (x = 0.2, 0.4) or A‐,B‐sites (x = 0.6) of pyrochlore. The displacements of the A‐site atoms and O′ from the ideal sites are shown. For both dopants, the maximum dielectric constant ε′ was 98, and the dielectric losses remain reasonably close to the values below 0.0058 at x = 0.4, 25 °C, 1 MHz. A drop of ε′ is observed at the other dopants concentrations. With the dopant content rising, the temperature coefficient of capacitance (TCC) increases and is positive (579 ÷ 782 ppm/°C) below room temperature (RT) and then becomes negative (−49 ÷ −220 ppm/°C) above RT. The revealed low‐temperature relaxation process could be associated with jumps of the A‐ions within the A2O′ substructure.