Temperature sensors based on GaPO4

Results of investigations of temperature sensors using singly rotated Gallium Orthophosphate (GaPO₄) Y-cut resonators are presented in this paper. Depending on rotating angle the most important parameters - sensitivity, resolution and linearity differ in a wide range. Theoretical calculations leads to cuts owning nearly a linear response with sensitivity between 44.5 ppm/°C and 46.5 ppm/°C within a temperature range from room temperature to 600°C with a high resolution of about 10^-6°C. First measurements confirm the theoretically predicted sensitivity. The broad thermal stability range of GaPO₄ can also be used for temperature sensors based on surface acoustic wave devices. By theoretical calculations, suitable orientations with high temperature coefficients are identified.