Impacts of Al₂O₃ Doping on Microstructure, Phase Constitution and Microwave Dielectric Properties of Ca_0.61Nd_0.26TiO₃ Ceramics

Abstract

The effects of Al₂O₃ addition on microstructure, phase evolution and microwave dielectric properties of Ca_0.61Nd_0.26TiO₃ – x mol Al₂O₃ (x = 0, 0.025, 0.05, 0.075, 0.1) ceramics have been investigated in this study. With x increasing from 0 to 0.05, the system maintained a single perovskite phase while bulk density decreased rapidly due to grain size degradation. Correspondingly, dielectric constant (ϵ_r) decreased from 103 to 79.2 and temperature coefficient of resonant frequency (τ_f) dropped from +247 to +159.3 ppm/°C. Moreover, anti-reduction of Ti⁴⁺ gave rise to a nearly doubled Q×f value, from 8600 to 15500 GHz. For 0.075≤x≤0.1, X-ray diffraction results showed a secondary phase whose peaks were consistent with Ca₂Nb₂O₇ phase, resulting in decreased microwave dielectric properties.

GRAPHICAL ABSTRACT

Keywords:

• Microstructure
• X-ray techniques
• Microwave dielectric property