Investigation of the incommensurate (INC) phase between α and β phases in quartz and related materials

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2021-2-10
Ateş, Simge
Incommensurate (INC) phase as an intermediate sinusoidal phase which exists in anarrow temperature range (∼1.3◦C) between the low-temperatureαand the high-temperatureβphases in quartz, is investigated extensively. The phase transitions oftheα-INC and INC-βoccurring as first order and second order type, respectively,are studied using the experimental data from the literature. Order-disorder transi-tion between theαandβquartz through the incommensurate phase is described bytemperature and pressure dependence of the experimentally measurable macroscopicparameters in relation to the microscopic order parameter according to various mod-els, mainly the Landau phenomenological model.Our methods in this study form a guide to investigate crystals with similar phasediagram with quartz as tridymite and cristobalite, and incommensurate phases in someother materials with similar crystal structure to quartz such asNaNO2,K2SeO4andAlPO4.

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Citation Formats
S. Ateş, “Investigation of the incommensurate (INC) phase between α and β phases in quartz and related materials,” Ph.D. - Doctoral Program, Middle East Technical University, 2021.