METHOD OF MICROWAVE ACOUSTIC RESEARCH OF MATERIALS UNDER THE HIGH PRESSURE

The arrangement of a new integrated measuring system (IMS) "HBAR + DAC" and its application to study changes in the acoustic properties of a paper and polycrystalline molybdenum samples under the influence of high pressure are discussed. When creating an IMS for the synthe-sis of piezoelectric films of aluminum-scandium nitride, the magnetron deposition method was used. The quality and thickness of the films were controlled by X-ray diffraction analysis and atomic force microscopy. For the first time, it is shown that the HBAR in the IMS content has good operational characteristics in the microwave band up to 8.8 GHz under the high-pressure impact on the samples. A decrease in the Q-factor of an HBAR as a sensitive element occurred to values of similar to 2500 - 3000 at the upper pressure limit, which is quite sufficient for accurate measurements of the resonant frequencies of acoustic overtones. The possibilities of IMS for studying the features in the behavior of solids under the high-pressure impact and the registration of plastic deformations in metals are demonstrated. It is found that the pressure dependence of the relative frequency shift of overtones during compression of a paper sample has a linear character. Thanks to this, the calibration of the high-pressure chamber on diamond anvils was performed using the RAMAN method. It is found that the frequency shift of overtones allows more accurately determining the stresses in the diamond anvil up to 5 GPa. When compressing a sample of polycrystalline molyb-denum, the phenomena of plastic deformation and creep, as well as the transit flight of an acoustic wave through the sample, starting from a pressure of 3 GPa, were detected. The results obtained will be useful for researchers, students and postgraduates in the fields of high pressure physics and physical acoustics.