Effect of Ti-doped LaAlO3 on microwave dielectric properties

Abstract

The development of mobile communication technology urgently needs microwave dielectric ceramic materials with high-temperature stability. Herein, LaAl_1-xTi_xO₃ (LATO, x = 0–0.4) ceramic samples were synthesized by solid-state reaction method. Subsequently, the microstructure of the ceramics was studied and their microwave dielectric properties were measured. The experimental results show that after sintering at 1525 ℃ for 4 h, the optimum microwave dielectric properties are obtained at x = 0.2, ε_r = 14.93, Q × f = 8484 GHz, and τ_f = -6.99 ppm/℃. As the value of x increases, the values of ε_r and Q × f first increase and then decrease, which is attributed to changes in the stability of the material structure and adjustments in the symmetric tensile mode of the Al/Ti–O bond. It is worth noting that the addition of Ti⁴⁺ effectively improved the resonant frequency temperature coefficient of the material. It is predicted that the addition of Ti⁴⁺ can adjust the inclination of oxygen octahedra and promote the orientation of τ_f toward 0. This work confirms the significant potential of LATO (x = 0–0.4) ceramics in enhancing the temperature stability of microwave devices.