研究目的
To demonstrate the existence of inversion twins within single crystals of YAl3(BO3)4 (YAB) and K2Al2B2O7 (KABO) using measurements of optical activity and to determine the optical rotatory dispersion of YAB and KABO throughout the visible spectrum.
研究成果
The study successfully demonstrated the existence of inversion twins within YAB and KABO crystals using measurements of optical activity. The derived dispersion relations for the rotatory power of YAB and KABO provide a method to assess crystal quality and select twin-free specimens. The findings suggest that the optical activity of these materials arises mainly from the arrangement of borate groups in their crystal structures.
研究不足
The study is limited by the spatial resolution of the laser beam used for space-resolved measurements, which was about 1 mm. Additionally, the presence of fine lamellar intergrowths of right- and left-handed domains may affect the accuracy of the rotatory power measurements.
1：Experimental Design and Method Selection:
The study used a spectrophotometer with rotatable polarizers to measure the optical rotatory dispersion of YAB and KABO crystals. Space-resolved measurements of the optical rotation were conducted to relate to the twin structure.
2：Sample Selection and Data Sources:
YAB and KABO crystals were grown by the top-seeded solution growth (TSSG) technique. Platelets were cut and polished to plane-parallel sections perpendicular to the trigonal symmetry axis.
3：List of Experimental Equipment and Materials:
A PerkinElmer Lambda 1050 spectrophotometer equipped with rotatable calcite polarizers, deuterium and tungsten lamps, photomultiplier, InGaAs photodiode, and a He-Ne laser setup with rotatable Glan-Thompson polarizers.
4：Experimental Procedures and Operational Workflow:
The optical rotation angle was measured as a function of wavelength using the spectrophotometer. Space-resolved measurements were conducted using a He-Ne laser to detect variations in optical rotation within individual crystals.
5：Data Analysis Methods:
The optical rotation angles were analyzed to determine the rotatory power and dispersion relations. The data were fit to semi-empirical formalisms based on the theory of circular dichroism.
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