Crystal Structure And Ferroelectric Evidence Of Baznsi3o8, A Low-Permittivity Microwave Dielectric Ceramic

BaZnSi3O8 ceramic was prepared by the conventional solid-state method and sintered at 1100 degrees C. XRD and synchrotron Rietveld refinement analyses revealed the BaZnSi3O8 ceramic presented a monoclinic structure with a space group of P2(1)/a (No.14), which is reported for the first time. The BaZnSi3O8 ceramic presented a weak ferroelectricity, which was confirmed by the P-E loop and the 90 degrees nanoscale ferroelectric domain. Although epsilon(r)-T displayed two epsilon(r) abnormal peaks at 400 degrees C and 460 degrees C, the Curie temperature (T-c) was located at 460 degrees C according to the dielectric loss and Curie-Weiss law. Moreover, the BaZnSi3O8 ceramic exhibited optimized microwave dielectric properties with epsilon(r)=6.55, Qxf=52400 GHz, and tau(f)=-24.5 ppm/degrees C. Hence, the BaZnSi3O8 ceramic in the ternary BaO-ZnO-SiO2 system possessed both weak ferroelectricity and microwave dielectric properties. These results are expected to break the technical barrier of ferroelectric phase shifter applications in microwave and even millimeter-wave frequency bands.