CRYSTAL-STRUCTURE AND MICROWAVE DIELECTRIC-PROPERTIES OF BA(ZN1/3TA2/3)O3-(SR,BA)(GA1/2TA1/2)O3 CERAMICS

The microwave dielectric properties and crystal structure of Ba(Zn1/3Ta2/3)O3-(Sr,Ba)(Ga1/2Ta1/2)O3 ceramics were investigated in the present study. The Q value of Ba(Zn1/3Ta2/3)O3 was improved by adding 5 mol% Sr(Ga1/2Ta1/2)O3. The maximum Q value of Q x f = 162000 GHz was obtained at 0.95Ba(Zn1/3Ta2/3)O3. 0.05Sr(Ga1/2Ta1/2)O3. For this composition, a lattice super structure caused by hexagonal ordering was observed. A further improvement in the Q value was attained when some Sr was replaced with Ba, and 0.95Ba(Zn1/3Ta2/3)O3.0.05(Sr0.25Ba0.75)(Ga1/2Ta1/2)O3 exhibited a maximum Q value such that Q x f = 210000 GHz. Despite the increased Q value with the replacement of Sr by Ba, the c/a value, which indicates the degree of lattice distortion, remained constant near square-root 3/2. The Q value thus improved without lattice distortion in the system Ba(Zn1/3Ta2/3)O3-(Sr,Ba)(Ga1/2Ta1/2)O3, whereas the improvement of Q value increased with lattice distortion in the solid solution system with Ba(Zn1/3Ta2/3)O3 as an end member.