Structure, Raman spectra and microwave dielectric properties of novel garnet-type Ca3MZrGe3O12 (M = Co, Zn) ceramics

Two novel garnet-type ceramics Ca3MZrGe3O12 (M = Co and Zn) with pure phase were prepared through a solid-state reaction method. Structure-property relationships were studied by the Rietveld refinement and Raman spectra. The appearance of two weak symmetric stretching vibrational peaks in Ca3ZnZrGe3O12 might be due to the lower ordering. Higher Q x f value in Co-analogue was related to the larger packing fraction and the lower FWHM of A1g mode. The smaller oxygen bond valence in Ca3CoZrGe3O12 indicates a smaller tf value. At the optimized sintering temperature of 1280 degrees C, Ca3CoZrGe3O12 shows desirable microwave dielectric properties with er of 10.37, Q x f value of 60,100 GHz, and tf value of -28.5 ppm/degrees C. The Ca3ZnZrGe3O12 ceramic sintered at 1200 degrees C has the best microwave dielectric properties with er of 10.48, Q x f value of 49,700 GHz, and tf value of -35.8 ppm/degrees C.

Automated summary

Two novel garnet-type ceramics, Ca3MZrGe3O12 (M = Co and Zn), were successfully prepared with Ca3ZnZrGe3O12 exhibiting lower ordering and Ca3CoZrGe3O12 showing better microwave dielectric properties.