Influence of sintering temperature on microwave dielectric property and crystal structure of corundum-structured Mg_4NbSbO_9 ceramic

摘要

The relationships between the influence of the sintering temperature on the microwave dielectric properties and crystal structure of Mg_4NbSbO_9 (MNS) ceramics with corundum structure were investigated in this study. From the XRPD patterns, it was found that the MgO compound was identified as a secondary phase in the XRPD patterns of MNS ceramic when the samples were sintered at the sintering temperatures higher than 1500 deg C because of the vaporization of Sb in MNS ceramic. The dielectric constants of MNS ceramic increased from 10 to 13 in the temperature range of 1375-1500 deg C, whereas those of MNS ceramic decreased at the sintering temperatures above 1550 deg C. The quality factors (Q centre dot f) of MNS ceramic also decreased from 275,000 to 5000 GHz at the sintering temperatures above 1550 deg C. Such a decrease in Q centre dot f values may be related to the vaporization of Sb and the formation of a secondary phase. The temperature coefficient of resonant frequency was ranged from -56 to -46 ppm/deg C.