A new type of microwave dielectric ceramic based on K2O–SrO–P2O5 composition with high quality factor and low sintering temperature

A new type of microwave dielectric ceramics with low dielectric loss was fabricated through a traditional solid-phase method. X-ray diffraction and density tests showed that KSrPO 4 ceramics with a single orthorhombic phase could be synthesized and densified at 950 °C, and the crystal structure of KSrPO 4 was further confirmed by Rietveld refinement analysis. The densification temperature of KSrPO 4 was lower than 961 °C, indicating the ceramics could be used in LTCC devices. Additionally, based on the complex chemical bond theory, some internal parameters of KSrPO 4 ceramics were calculated and the effects of these parameters on the properties of KSrPO 4 were systematically analyzed for the first time. Furthermore, the composite dielectric constant and loss of KSrPO 4 ceramics were analyzed by infrared reflectance spectroscopy, and the theoretical loss and the actual loss were compared. Finally, a vector network analyzer was employed to measure the microwave dielectric properties of all samples. The results showed that KSrPO 4 sintered at 950 °C obtain the best microwave dielectric properties, including ε r  = 7.85, Q·f  = 34,527 GHz (at 10.43 GHz) and τ f  = −14.82 ppm/°C.