Mixture behavior and microwave dielectric properties of (1 - x)Ca₂P₂O₇-xTiO₂

(1 - x)β-Ca₂P₂O₇-xTiO₂ were prepared by solid-state reaction. The mixture behavior and microwave dielectric properties were investigated using X-ray powder diffraction and a network analyzer, respectively. X-ray powder diffraction patterns showed that β-Ca₂P₂ O₇ and TiO₂ existed in a mixture form, which was also confirmed by SEM analysis. It was shown that TiO₂, which has positive temperature coefficient of the resonant frequency (τ_f), compensated the negative τ_f of β-Ca₂P₂O₇ (-53 ppm/°C) through mixture formation. The variation of dielectric properties with a function of TiO₂ contents could be explained using mixture rule. In the 0.3 < x < 0.4 regions, τ_f value could be successfully reduced almost zero. In particular, at x = 0.3, good microwave dielectric properties was obtained: Q × f = 44,000, ε_r = 10.9, and τ_f = -11 ppm/°C.