Levit Rafael, Barrio Maria, Veglio Nestor, Tamarit Josep Ll, Negrier Philippe, Pardo Luis C, Sanchez-Marcos Jorge, Mondieig Denise
Departament de Física i Enginyeria Nuclear, E.T.S.E.I.B., Universitat Politècnica de Catalunya, Diagonal, 647, 08028 Barcelona, Catalonia, Spain.
J Phys Chem B. 2008 Nov 6;112(44):13916-22. doi: 10.1021/jp806180y. Epub 2008 Oct 10.
The experimental phase diagram of the CBrCl3+CBr4 system has been determined by means of X-ray powder diffraction and thermal analysis techniques from 200 K to the liquid state. Before melting, the two components have the same orientationally disordered (OD) face-centered cubic phase, and solid-liquid equilibrium is explained by simple isomorphism. The application of multiple crossed isopolymorphism formalism to the low-temperature solid-solid equilibria has enabled the inference of an OD rhombohedral metastable (at normal pressure) phase for CBr4. Experimental determination of the pressure-volume-temperature and construction of the pressure-temperature phase diagrams for CBr4 reveal the existence of a high-pressure phase, the rhombohedral symmetry of which is inferred by means of the thermodynamic assessment of the experimental phase diagram and demonstrated by means of high-pressure neutron diffraction measurements. The procedure used in this work confirms the connection between the appearance of metastable phases at normal pressure and their existence at high-pressure.
通过X射线粉末衍射和热分析技术，测定了CBrCl₃ + CBr₄体系从200 K到液态的实验相图。在熔化之前，两种组分具有相同的取向无序（OD）面心立方相，固液平衡可用简单同构来解释。将多重交叉同多晶型形式应用于低温固-固平衡，使得能够推断出CBr₄的一个OD菱面体亚稳（常压下）相。对CBr₄的压力-体积-温度进行实验测定并构建压力-温度相图，揭示了一种高压相的存在，通过对实验相图的热力学评估推断出其菱面体对称性，并通过高压中子衍射测量得到证实。本工作中使用的方法证实了常压下亚稳相的出现与其在高压下的存在之间的联系。
