PROPERTIES OF MN-DOPED BATI4O9-ZNO-TA2O5 CERAMICS .1. REACTION SEQUENCE, MICROSTRUCTURAL ANALYSIS AND MICRO WAVE DIELECTRIC-PROPERTIES

In Part I, the reaction sequence, microstructural analysis and microwave dielectric properties of manganese-doped BaTi4O9+ZnO+Ta2O5 ceramics are discussed. This composition undergoes complex intermediate reactions during calcination. However, the final crystal phases after the sintering process were identical regardless of calcination temperature. Meanwhile, different calcination temperatures affect the relative volume fractions of the BaZn2Ti4O11 phase and result in variations in T-f values. To analyse the microstructure, SEM, TEM and EDS analysis were performed. Mn dopants greatly enhanced the Q factor, up to 11 000 at 4.5 GHz, whereas undoped ceramics indicated a high loss, probably due to the formation of Ti3+ during sintering in air.