V.I. Anisimkin - Dr.Sc. (Phys.-Math.), Chief Research Scientist, Kotel-nikov Institute of Radioengineering and Electronics RAS (Moscow). E-mail: anis@cplire.ru N.V. Voronova - Head of the Photomasks Laboratory, Acoustoelectronic & Piezokeramic «ELPA» Corporation. E-mail: vonavl@mail.ru М.А. Zemlyanitsin - Leading Engineer, Kotel-nikov Institute of Radioengineering and Electronics RAS (Moscow) Yu.V. Pushkov - Engineer, Acoustoelectronic & Piezokeramic «ELPA» Corporation I.I. Pyataikin - Ph.D. (Phys.-Math.), Senior Research Scientist, Kotel-nikov Institute of Radioengineering and Electronics RAS (Moscow)

The changes in surface and plate acoustic wave velocities propagating in heated (-100 С) piezoelectric crystals of quartz, lithium niobate, and bismuth silicon oxide affected by different gases and laminar gas flows are measured. The methods of rejecting undesirable gas responses are developed basing on а) proper selection of a plate mode number, b) minimizing the temperature coefficient of delay by using its temperature dependence, c) equalizing thermal conductivity coefficients for test and calibration gases, d) choosing proper velocities of gas flows. Each method is demonstrated by relevant examples: the dependence of the thermal conductivity responses on the order of the modes and gas concentration is presented for ST,X+90° quartz as a substrate and Ar as a gas; the monitoring of the value and the sign of the response through the temperature variations of the thermal coefficient of delay is demonstrated using ST,X-quartz as a substrate and Ar, He as test gases; the possibility of rejection of the thermal conductivity response by equalizing the gas thermal conductivity coefficients and/or by selecting a gas flow rate are experimentally verified for (001)<110>-Bi12SiO20 as a substrate and 0.2 % EtOH in Ar as test gas and for YZ-LiNbO3 as a substrate and Ar, dry air, N2, O2 as test gases, respectively.

 

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