Composition, temperature, and pressure dependence of phonon modes in complex hydrous silicates

角闪石（AB2C5T8O22W2, C = M12M22M3）和电气石（XY3Z6T6O18(BO3)3V3W）是两种化学成分相当复杂的矿物超群，具有多个可被各种化学元素占据的晶体位置。角闪石和电气石的晶体化学研究在地球科学中具有重要的意义，特别是在使用基于主元素和次要元素的岩石学模型来分析寄主岩石的类型和岩石成因时。这些研究对于更好地理解矿物在不同温度和压力下的热力学行为以及矿物性质的成分依赖性也至关重要。因此，它们在材料科学和环境科学以及宝石学和文化遗产文物研究中也有影响。声子是弹性和热性质的微观来源，因此，研究组成x、温度T和压力p这三个关键热力学变量对原子动力学的影响具有重要意义。综合分析闪石和电气石中（x， T, p）与声子之间的关系是先前MI 1127/7-1项目和SCHL 549/6-1卫星项目的目标。因此，本继续项目的主要目标是通过研究更多的矿物种类，进一步扩展对复杂含水硅酸盐中声子态密度与晶体化学关系的基本认识，并完成对角闪石热弹性行为的研究。主要有三个目的：(1)碱电气石Cr-V-Al三元体系中化学-声子相互作用的分析；（ii）研究四面体配位Al以及八面体配位Al和Fe3+对角闪石oh -拉伸和框架振动的影响，以及（iii）研究各种角闪石物种声子模式的T和p演化。将进一步采用单模/双模方法研究电气石系列：氧导石-氧钒导石-氧铬导石。这些结果还将与对应的三价铁的结果进行比较，以更好地了解Y-和z -位d元素对电气石原子动力学的影响。对角闪石的组成-声子关系的研究将扩展到框架振动以及含tal的角闪石物种。还将特别注意铁状角闪石。通过声子波数和宽度的变化趋势，研究了T和p诱导的角闪石相变的化学重整化。含铁角闪石的氧化过程也将通过高达1400 K的原位拉曼光谱进行研究，并将结果与含铁电气石的结果进行比较。

Amphiboles (AB2C5T8O22W2, C = M12M22M3) and tourmalines (XY3Z6T6O18(BO3)3V3W) are two mineral supergroups with a rather complex chemical composition, having several crystallographic sites that can be occupied by various chemical elements. Crystal-chemistry studies of amphiboles and tourmalines have important implications in Earth sciences, in particular when using petrologic models based on major and minor elements to analyze the type and petrogenesis of host rocks. Such studies are also vital to better understand the thermodynamic behaviour of minerals at various temperatures and pressures as well as the compositional dependencies of mineral properties. Hence, they have implications also in materials science and environmental science as well as in gemmology and studies of cultural-heritage artefacts. Phonons are the microscopic origin of elastic and thermal properties and therefore, it is of great significance to study the influence of each of the three key thermodynamic variables: composition x, temperature T, and pressure p, on the atomic dynamics. A comprehensive analysis of the relation between (x, T, p) and phonons in amphiboles and tourmalines was the objective of the previous project MI 1127/7-1 and the satellite project SCHL 549/6-1. Thus, the major goal of this continuation project is to further extend the fundamental understanding of the relation between phonon density of states and crystal chemistry in complex hydrous silicates by studying more mineral species as well as to complete the study of thermal and elastic behaviour of amphiboles. The three main aims are: (i) analysis of the chemistry-phonon interplay in the Cr-V-Al ternary system of alkali tourmalines; (ii) studies of the influence of tetrahedrally coordinated Al as well as of octahedrally coordinated Al and Fe3+ on the OH-stretching and framework vibrations of amphiboles, and (iii) studies of T and p evolution of phonon modes in various amphibole species. The one-mode/two-mode approach will be further used to study the tourmaline series: oxy-dravite - oxy-vanadium-dravite - oxy-chromium-dravite. The results will be also compared to those for the corresponding trivalent-iron counterparts, to better understand the effect of Y- and Z-site d elements on the atomic dynamics of tourmalines. The studies of composition-phonon relations for amphiboles will be extended to framework vibrations as well as to TAl-containing amphiboles species. Special attention will be also given to ferri amphiboles. The chemical renormalization of T- and p-induced phase transitions in amphiboles is going to be studied via the trends of phonon wavenumbers and widths. Oxidation processes in Fe-containing amphiboles are going also to be studied via in situ Raman spectroscopy up to 1400 K and the results will be compared with those achieved for Fe-bearing tourmalines.