|Physical acoustics of solid state|
Investigation of high-frequency acoustical waves in solids is one of the most effective ways to investigate internal structure and physical properties of these mediums. Usually, main attention is paid to investigations of crystalline samples. Acoustical waves penetrate easily into any crystal, actively interact with atomic lattice, admixtures, electrons, and often give unique information about propagation medium. Acoustics has achieved a great success in investigation of electron structure of metals and superconductors. A lot of interesting information about dielectrics, semiconductors, ferromagnetics, ferroelectrics and so on has been obtained.
At the prime stage investigation of high-frequency Acoustics waves has been carried out by means of Brillouin light diffusion. Later on the use of very thin piezoelectrical plates as converters permitted to obtain sufficiently powerful acoustical beams, which could have already been used effectively both for investigation of properties of different materials and practical purposes.
At the present, hypersonic oscillations over the range of extreme terahertz frequencies are obtained in physical laboratories.
Creation of interdigitated converters, which permitted to use high-frequency acoustic surface waves, was of great importance.
Numerous investigations with the use of high-frequency acoustical waves in solids were carried out by many research centres, universities, laboratories in different countries all over the world.
Abroad the most active work was realized in the USA, Japan, France, and the UK.
In Russia active work was carried out in the Institute of Radiotechnics and Electronics RAS, the Institute of physical technology named after A. F. Ioffe, Acoustics Institute named after academician N. N. Andreyev, Moscow State University named after M. V. Lomonosov, Kazan Institute of physical technology, and in many others institutions.
At present, acoustical phenomena in crystals are widely used in technical applications. Appearance of two absolutely new fields of investigation at the turn of physics and technics: acoustoelectronics and acoustooptics should be declared as the greatest achievement.
Investigations of solids by means of methods of physical acoustics have been carried out in Acoustics Institute since 60-s.
Under the direction of I. A. Victorov the most important characteristics of acoustic surface waves (ASW) were investigated theoretically and experimentally. Their excitation, propagation, properties in dielectrics, semiconductors, layer structures and etc were studied.
Influence of surface states of crystal on ASW propagation was examined for the first time. Sound amplification by carrier drift in piezosemiconductors was diversely studied. For the first time, amplification of ASW was observed experimentally.
Under the direction of V. F. Kazantsev complicated phenomenon of magnetoacoustic resonance was investigated.
In theoretical works of A. A. Chaban investigation of nonlinear interactions of acoustical waves in alternating electric field was started. Phenomenon of appearance of additional acoustical impulse with reverse direction of propagation and initiation of electric signal having type of convolution were predicted.
Phenomena like acoustoelectric memory in piezosemiconductors and piezodielectric powders were explained.
Interaction of acoustical waves with light lattices in piezosemiconductors was examined theoretically and experimentally. Different types of acoustical interaction and photoacoustical memory in layer structures, acoustophotorefractive effect, various types of interaction of sound with holographic arrays in dielectrics, semiconductors, layer structures were studied (P. A. Pyatakov, A. A. Chaban).
Theoretical investigations of high-temperature superconductors, particularly changes of their properties under the influence of pressure were carried out (I. A. Chaban).
At present, theoretical and experimental investigations of new perspective materials – fullerens have been started.