粉末压片与晶体测试结果存在较大差异,表现为粉末压片无法测出预期的晶体红外透过光谱,且其在晶体的红外截止波段会出现异常透过峰。从原理上分析了上述现象,并通过简化晶体红外介电性能的理论模型,提出了一种基于多晶粉末透射谱测定晶体红外介电性能的方法。用该方法对AgGaS2、ZnGeP2晶体的红外介电性能(如红外截止波长、长光学声子横模频率)进行了测定,结果与直接测量单晶基本一致。本研究对探索新型红外功能晶体材料具有重要意义。

There is much difference between the measurement results of polycrystalline powder pellets and single crystals. The infrared transmission spectra of single crystals can't be obtained from the powder pellets and there is an abnormal transmission peak in the infrared cut-off band on the spectra of polycrystalline powder pellets. The above phenomena are analyzed in principle. In this work, by simplifying the theoretical model of infrared dielectric properties of crystals, a method for measuring infrared dielectric properties of crystals based on transmission spectra of polycrystalline powder pellets is proposed. The infrared dielectric properties of AgGaS₂ and ZnGeP₂ crystals, such as infrared cut-off wavelength and long optical phonon transverse mode frequency, have been measured by this method. The results are in good agreement with those of single crystals. This study is of great value for screening high-quality materials in the exploration of new infrared functional crystals.