MICROSTRUCTURAL RELATIONS IN BZS PYROCHLORE-ZNO MIXTURES

ZnO-pyrochlore mixtures were produced with different Bi2O3 and Sb2O3 c ontents but maintaining rite Sb/Bi ratio = 1, which is the molar ratio in Bi3/2ZnSb3/2O7 pyrochlore. Increased cooling rates and sintering t emperatures reduced the amount of pyrochlore formed Pyrochlore retards densification rates by retaining Bi2O3 and forming a skeletal net, wo rk. Microstructures of quenched and slow-cooled samples were similar c onsisting of ZnO, spinel and a third phase. In the former this was Bi- rich intergranular phase(s) whereas it was pyrochlore in the latter. A lthough pyrochlore does not have a direct effect on the ZnO grain grow th above 1050 degrees C, it limits grain growth below this temperature . (C) 1997 Elsevier Science Limited.