Microwave Dielectric Properties of (A2+1/3 B5+2/3)0.5Ti0.5O2 (A2+=Zn, Mg, B5+=Nb, Ta) Ceramics

Dielectric properties of (A
²⁺

_1/3
B
⁵⁺

_2/3
)
_0.5
Ti
_0.5
O
₂
(A=Zn
²⁺
, Mg, B
⁵⁺
=Nb, Ta) ceramics were investigated at microwave frequencies. Dielectric properties were strongly dependent on the structural characteristics and cooling rate. The specimens with Nb
⁵⁺
showed larger dielectric constant (
K
) than those with Ta
⁵⁺
due to the decrease of bond valence. Quality factor (
Qf
) of the specimens was dependent on the reduction of Ti
⁴⁺
ion as well as microstructure. Temperature coefficients of the resonant frequencies (
TCF
) of the specimens with Nb
⁵⁺
were larger than those with Ta
⁵⁺
. These results could be attributed to the changes of oxygen octahedral distortion.