Observation of liquid‐solid phase transitions using a shear horizontal acoustic plate mode sensor

We present a method for characterizing liquid‐solid phase transitions by using an acoustic shear horizontal (SH) plate mode sensor. The sensor consists of a Y‐cut quartz plate provided with suitable interdigital transducers on the lower surface. To study the temporal evolution of a phase transition, the liquid is deposited in a thin layer on the upper surface and the SH mode attenuation is observed as a function of time during a programed temperature change. With this sensor the theoretical time resolution is about 1 μs. Experimental results are presented for the liquid‐solid transition for deionized water, tap water, and 90%/10% mixture of tap water and ethanol, measured with an instrument time resolution of 50 ms.