Short- and long-term stability of resonant quartz temperature sensors

A new miniaturized design of the thermosensitive quartz resonator (TSQR) using an NLC cut (yxl/-31deg30psila) with a fundamental frequency of 29.3 MHz was created in the Acoustoelectronics Laboratory of ISSP-BAS for use in a wide temperature range (4.2 K to 450 K) as highly sensitive quartz temperature sensors (QTS). This paper presents the results of the investigations of the short- and long-term frequency stability of QTS. The short-term frequency stability of QTS was measured for averaging times up to 150 s at three constant temperatures: liquid helium (4.2 K), liquid nitrogen (77 K), and melting ice (0degC). The short-term frequency stability is 6.8 times 10^-9 at 0degC for t = 15 s, which permits a temperature sensitivity of 2 times 10^-4 K. The long-term stability (aging) was investigated at room temperature and at 80deg C for 500 days. The aging characteristics at 25 degC and 80 degC are compared. It was observed that the frequency change does not exceed 5 times 10^-7 after the 25th day of accelerated aging at 80 degC. This guarantees a reliable operation of the sensor, without additional calibration, for several years.