Effect of Crystal Structure on Microwave Dielectric Properties of (Ni1/3B2/3)1-xTixO2 (B=Nb and Ta)

Dependence of microwave dielectric properties on the crystal structure of (Ni1/3B2/3)1-xTixO2 (B5+=Nb, Ta, 0.3≤x≤0.6) were investigated. Single phase of tetragonal rutile structure was detected through the entire range of compositions (0.3≤x≤0.6). Dielectric constant (K) and the temperature coefficient of resonant frequency (TCF) of (Ni1/3B2/3)1-xTixO2 (B5+=Nb, Ta) increased with an increase of TiO2 content due to the increase of bond length ratio of (dapical)/(dequatorial), and the octahedral distortion of rutile structure, respectively. The specimens with smaller Ti content and/or B5+=Ta showed larger Qf value than those with larger Ti content and/or B5+=Nb.