Raman scattering from three phases in LiIO3 |
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Authors: | F.E.A. Melo F. Cerdeira V. Lemos |
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Affiliation: | School of Physics, University of Hyderabad Hyderabad 500 134, India |
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Abstract: | We studied the temperature dependence of the Raman spectrum of LiIO3, from room temperature up to t ~ 350°C. Two discontinuous changes in the spectrum are observed as temperature increases. The first one is reversible and occurs in a temperature range between 215°C and 260°C, depending upon sample origin (single crystal or powder) and thermal history. The second occurs at t ? 290°C and becomes irreversible once the samples are heated above 340°C. Each phase has a characteristic spectrum, distinct from that of the other two. Although the occurence of these phase changes are in complete agreement with studies made with X-ray diffraction and differential thermal analysis (DTA), it is at variance with previous Raman and infrared work which report no qualitative change in spectrum at the α ? γ phase transition. We believe this disagreement comes about because our measurements are the first ones so far to have actually passed through the transition. |
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