Kohutych A. Inelastic light scattering and acoustical properties of Sn2P2(SexS1 x)6 ferroelectric crystals

Українська версія

Thesis for the degree of Candidate of Sciences (CSc)

State registration number

0410U005926

Thesis Registration Form

0410U005926.pdf

Applicant for

Kohutych Anton Antonovych

Specialization

01.04.10 - Фізика напівпровідників і діелектриків

Date of defense

29-10-2010

Specialized Academic Board

Д 61.051.01

Essay

The thesis is dedicated to the investigation of the inelastic light scattering, as well as to the research of the elastic properties anisotropy, lattice dynamics anharmonicity and acoustic properties anomalies of Sn2P2S6 and Sn2P2(Se0.28S0.72)6 crystals near their phase transitions, and to the analysis of the influence of hydrostatic pressure on the temperature anomalies of ultrasound velocity. It was shown that the temperature anomaly and frequency depend-ence of the sound attenuation could be described with an account of several relaxation times and mode Gruneisen co-efficients. The negative contribution of the optic modes to the Gruneisen coefficient in a wide temperature range of the ferroelectric phase was found. The significant decrease of the longitudinal and transverse acoustic phonons veloc-ity was also found near the Lifshitz point. The tricritical behaviour near 0.4 GPa was detected in Sn2P2S6 crystal.

Thesis supervisor

Vysochanskii Yulian Myronovych

Official opponents

Козловський Михайло Павлович
Пуга Павло Павлович

Files

aref.doc

dis.doc

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