Low loss and middle permittivity of (1 − x) Ca4La2Ti5O17–xNdAlO3 dielectric resonators with near-zero temperature coefficient of the resonant frequency

Abstract

The crystal structures, microstructure and microwave dielectric properties of (1 − x) Ca4La2Ti5O17–xNdAlO3 (0 ≤ x ≤ 0.7) ceramic system have been investigated. The results show that all the compositions form single-phase ceramics. The microwave dielectric properties are strongly correlated with composition, sintering temperature, grain sizes and lattice defects. The cell volume decreases because of the substitution of Al3+ for Ti4+ and Nd3+ for La3+ which is associated with a decrease in the permittivity. With increase in x value, the permittivity (e r ), temperature coefficient of resonant frequency (τ f ) and Q × f value decrease. A near-zero τ f is achieved at x = 0.6 with permittivity of 41.8 and Q × f value of 13,783 GHz.