Synthesis, characterization, and dielectric properties of low loss LaBO3 ceramics

The preparation, sintering behaviour, and dielectric properties of low loss LaBO3 ceramics have been investigated. Single-phase LaBO3 powder was synthesized by the conventional solid-state ceramics route and dense ceramics (relative density >96%) with uniform microstructure (grain size ∼30 μm) were obtained by sintering at 1300 °C in air. The electrical conductivity of LaBO3 follows the Arrhenius law and the related activation energies for electrical conduction of bulk and grain boundary are 0.62 eV and 0.90 eV, respectively. The LaBO3 ceramics sintered at 1300 °C exhibit excellent microwave dielectric properties with a relative permittivity, ɛr ∼ 11.8, a quality factor, Q × f0 value ∼76,869 GHz (at ∼15 GHz), and a negative temperature coefficient of resonant frequency τf ∼ −52 ppm/°C.