Properties of SAW synchronous two-port resonators on GdCa4O(BO3)3 crystal

Surface acoustic wave (SAW) synchronous two-port resonators were fabricated and measured on several orientations of the GdCa₄O(BO₃)₃ crystal. Resonance frequencies, insertion losses, and unloaded quality factors of the resonators, measured at room temperature, were in the ranges of about 432.3 to 437.5 MHz, 3.8 to 6.3 dB, and 6500 to 7500, respectively. The properties of this crystal, such as its lack of a phase transition up to its melting temperature of about 1500°C, a SAW temperature coefficient of frequency of about -80 ppm/°C, and good parameters of the resonators make the crystal attractive for high-temperature sensor applications.