Processing control of phase separation, cation ordering, and the dielectric properties of Ba_(3)(Co_(0.6)Zn_(0.4))Nb_(2)O_(9)

摘要

The dielectric and crystallographic properties of the ceramic Ba_(3)(Co_(0.6)Zn_(0.4))Nb_(2)O_(9) have beeninvestigated in relation to the processing schedule. Regimes incorporating slow cooling or a lower-temperature annealing stage are found to enhance the dielectric properties with the unloaded quality factor value increasing up to Q_(u)(velence)24 300 at 3.21 GHz, as compared with Q_(u)(velence)14 425 at 3.21 GHz using the standard schedule, while high relative permittivity (epsilon)_(r)(velence)34 is retained. High-resolution neutron powder diffraction studies reveal the materials to be biphasic assemblages of trigonal perovskites which exhibit varying degrees of cation order. The higher Q samples are found to contain the highest proportion of the fully cation-ordered phase.