PREPARATION AND DIELECTRIC PROPERTIES OF Bi_(1.5)Zn_(1.0)Nb_(1.5)O_7 AND Bi_(1.5)Zn_(0.92)Nb_(1.5)O_(6.92) PYROCHLORE CERAMICS

摘要

Bi_(1.5)Zn_(1.0)Nb_(1.5)O_7 and Bi_(1.5)Zn_(0.92)Nb_(1.5)O_(6.92) pyrochlore compositions were prepared and investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and their dielectric properties were measured. XRD of Bi_(1.5)Zn_(0.92)Nb_(1.5)O_(6.92)gave only single phase pyrochlore but second phases were observed in the XRD of Bi_(1.5)Zn_(1.0)Nb_(1.5)O_7. SEM supported X-ray results but in the microstructure of Bi_(1.5)Zn_(10)Nb_(1.5)O_7 composition a Zn-rich phase was also observed in additon to pyrochlore and ZnO. Bi_(1.5)Zn_(0.92)Nb_(1.5)O_(6.92) pyrochlore had higher dielectric constant and lower loss values than Bi_(1.5)ZnNb_(1.5)O_7 composition between 25-200 ℃ in the frequency range of 10 kHz-2 MHz, possibly due to presence of second phases in Bi_(1.5)ZnNb_(1.5)O_7.