研究目的
To study the anisotropy of acoustic and thermal expansion properties of TlInSe2 crystals, including the determination of all components of their elastic stiffness and compliance tensors, and to investigate phase transitions in these crystals.
研究成果
The symmetry of TlInSe2 becomes lower than tetragonal below the temperature point T1≈245 K. Anomalous behaviour of the acoustic and thermal expansion parameters occurs at T1≈245 K and T2≈145 K, indicating phase transitions. The study provides comprehensive data on the elastic and thermal expansion properties of TlInSe2 crystals, contributing to the understanding of their phase transitions and potential applications as acousto-optic materials.
研究不足
The measurements of the acoustic wave velocities in the temperature region below 166–185 K become difficult due to scattering of the acoustic waves and disappearing of the reflected signal. The data for the elasto-optic coefficients of TlInSe2 are not available in the literature, limiting the analysis of the acousto-optic figure of merit anisotropy.
1：Experimental Design and Method Selection:
The study involved experimental measurements of acoustic wave velocities and thermal expansion in TlInSe2 crystals. The elastic stiffness and compliance tensors were determined based on the acoustic wave velocities.
2：Sample Selection and Data Sources:
TlInSe2 crystals were synthesized and grown using a Bridgman–Stockbarger technique. The crystal structure was checked by X-ray diffraction.
3：List of Experimental Equipment and Materials:
A quartz-capacity dilatometer was used for thermal expansion measurements, and a pulse echo-overlap method was employed for acoustic wave velocity measurements. LiNbO3 transducers with a resonance frequency of 10MHz were used to excite the acoustic waves.
4：Experimental Procedures and Operational Workflow:
The relative thermal expansions were measured along the crystallographic axes a, b, and c. Acoustic wave velocities were measured for samples with faces perpendicular to principal crystallographic directions.
5：Data Analysis Methods:
The elastic-stiffness coefficients were calculated using the acoustic wave velocities determined experimentally. The obliquity angle and the angle of deviation from purely longitudinal and transverse polarization states were calculated using specific relations.
独家科研数据包，助您复现前沿成果，加速创新突破
获取完整内容
