拉曼光谱
吸收光谱法
吸收边
热致变色
磁滞
吸收(声学)
相变
化学
分析化学(期刊)
相(物质)
吸收带
材料科学
带隙
光学
凝聚态物理
物理
有机化学
光电子学
色谱法
复合材料
作者
V. Fernández,F. Jaqué,J.M. Calleja
标识
DOI:10.1016/0038-1098(86)90633-2
摘要
Abstract The thermochromic transition of Ag 2 HgI 4 has been studied by optical absorption and Raman spectroscopy. In the absorption spectra, the shift of the absorption edge towards lower energies at high temperatures is responsible for the yellow to red colour change of Ag 2 HgI> 4 ; this absorption edge is associated with a charge transfer process between electronic levels of Hg and I. The resulting hysteresis loop is similar to those found by reflectance measurements in Cu 2 HgI 4 . The Raman spectra show hysteresis loops for the position and half width of the ν 1 (HgI 4 2− , Td). There is a different behaviour between the first and subsequent heating cycles. The observed changes in the phase transition can be explained by assuming an increase of the interaction between the I and Ag atoms above the phase transition, and a consequent decrease of the IHg interaction. These changes would be induced by a decrease of the AgI distance above the phase transition, as a consequence of a structural distortion; consequently the HgI distance would increase and lead to the observed changes in the absorption spectrum.
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