Novel high Curie temperature Ba2ZnSi2O7 ferroelectrics with low-permittivity microwave dielectric properties

Ba2ZnSi2O7 ceramics with a monoclinic structure (C 2/c) were prepared using the conventional solid-state method at 1200 degrees C for 3 h in air. The as-prepared ceramics show signs of weak ferroelectricity from the P-E loop and ferroelectric domains with 90 degrees and 103 degrees directions. Although an epsilon(r) anomaly appears at approximately 510 degrees C, the Curie temperature (T-c) of the Ba2ZnSi2O7 ceramics is 750 C or higher. The ceramics also display low-permittivity microwave dielectric properties (epsilon(r)=8.09, Qxf=26,634 GHz, and tau(f)=51.46 ppm/degrees C). Therefore, the coexistence of high-T-c ferroelectricity and good microwave dielectric properties is beneficial to develop Ba2ZnSi2O7 ceramics into tunable-microwave and millimeter-wave devices such as capacitors, phase shifters, and oscillators. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.