单斜辉石固溶体CaMgSi_2O_6－NaAlSi_2O_6的临界相转变研究

对固溶体ＣａＭｇＳｉ＿２Ｏ＿６－ＮａＡｌＳｉ＿２Ｏ＿６相转变过程中的临界压力ｐ和临界温度Ｔ之间的关系进行了研究，得到ｐ与Ｔ之间为一线性关系：ｐ＝１．５４×１０￣（－２）Ｔ－１４．３（ＧＰａ）。另外，在临界条件下，对合成的单斜辉石的微观结构进行了ＳＥＭ观察，发现在较高的临界压力和临界温度下，样品晶粒粗壮、紧密，并且主要沿（００１）面生长成纤维状。控制一定的过冷却度使其在成核区停留一段时间之后升温到生长区，样品的ＳＥＭ观察结果显示与上述结论一致。

绿辉石固溶体NaAlSi_2O_6-CaMgSi_2O_6的合成和高压下熔化过程研究

在2×10~9～5×10~9Pa,1 000～2 300℃下合成了由二元组分NaAlSi_2O_6(Jadeit)-CaMgSi_2O_6(Diopside)构成的绿辉石,通过XRD分析数据计算了绿辉石Jd_xDi_(1-x)的晶胞参数随组成变化的规律。采用高温高压淬火法和XRD研究了Jd_xDi_(1-x)(x=0～1.0)高压下(2×10~9～5×10~9 Pa)的固溶关系,并根据Jd_xDi(1-x)的固溶相图计算了不同压力下的熔化热。

固熔体60%NaAlSi_2O_6-40%CaMgSi_2O_6在高温高压下的相图的研究

在1.0～5.0GPa、700～1750℃条件范围内,对固熔体0.6NaAlSi_2O_6-0.4CaMgSi_2O_6进行了研究,探讨了该固熔体在高温高压下的存在行为,研究了由非晶态玻璃向翡翠转化过程中γT作用的相图,得到的透辉石翡翠的晶胞参数为α=0.9439nm,b=0.8573nm,c=0.5233nm,β=107.28°和V=0.41702nm~3。本实验中合成的宝石级翡翠为色泽温润,具有玻璃光泽,半透明的极富观赏性的透辉石翡翠。

人造翡翠晶化区的研究

本文在１．１～５．５ＧＰａ压力、７５０～２０５０℃温度范围内通过对产物的ＸＲＤ分析得到了以非晶为原料时，纯硬玉翡翠ＮａＡｌＳｉ２Ｏ６和透辉石翡翠０．６ＮａＡｌＳｉ２Ｏ６－０．４ＣａＭｇＳｉ２Ｏ６的晶化区．经过对晶化区中不同Ｐ、Ｔ点产物的结晶度计算，将区域分成三个晶化子区，并对各子区中合成样品的硬度、微观结构、强度、颜色、透明性和稳定性等进行了研究．结果表明，在较高温度和压力的Ａ区产物具有高的结晶度、粗壮的线状微晶及高有序度的编织结构，对应着产物的高硬度、纯正的颜色及良好的透明度和稳定性，是宝石级翡翠的合成区.

钠铝辉石由非晶态到晶态的转化研究

在3．0－5．0GPa，1150－1750℃，1－480min条件范围内，合成了钠铝辉石，通过XRD、SEM及IR分析对比研究了人工翡翠和天然翡翠的微观精细结构；通过DAT分析测定了人工翡翠与天然翡翠的熔点，淬火实验检验了人工翡翠的熔点，通过退火及老化实验研究了翡翠的热稳定性。同时还就人工翡翠和天然翡翠的硬度、密度及折射率等其它物化性质进行了比较研究。根据上述研究总结了合成优质钠铝辉石翡翠的最佳实验条件为压力＞4．0GPa，温度＞1450℃，晶化时间＞45min。

NCMAS系统熔体结构和动力学性质压力效应的分子动力学研究

Molecular dynamics simulations were used to study the pressure dependence of the structure and the dynamic properties of forsterite melt (Mg_2SiO_4), diopside melt (CaMgSi_2O_6), anorthite melt (CaAl_2Si_2O_8), jadite melt (NaAlSi_2O_6) and albite melt (NaAlSi3O8) from 0 GPa to 25 GPa at about 2000 K and the following conclusions have been reached. Firstly, the ratio of NBO to T (NBO and T denote the content of non-bridging oxygen and the total content of Si~(4+) and Al~(3+) respectively) is closely related to the pressure and the composition of the melts. It decreases monotonously in forsterite, diopside and anorthite melts while increases at the initial stage and then decreases in jadite and albite melts with increasing pressure. At a fixed pressure, the shear viscosity of the melts decreases with increasing NBO/T and the variation rate is almost 150 times higher in fully polymerized melts than that in de-polymerized melts in comparison with anorthite melts. Secondly, it is generally accepted that the formation of the Si and A1 will promote the diffusion of the network-forming ions. The hypothesis is frequently employed to explain the emergence of the maximum self-diffusion coefficient of the network-forming ions in fully polymerized melts. However, I detected that the pressure corresponding to the peak of the self-diffusion coefficient of the network-forming ions is lower than that corresponding to the maximum content of Si and A1, and that there exists an approximately linear relationship between the self-diffusion coefficient of the ions and the breaking frequency of the bonds under a given pressure, which is different from the present understanding about the mechanism of self-diffusion. Thirdly, the relationship between the self-diffusion coefficient of Si~(4+), Al~(3+) and O~(2-) and the shear viscosity of the melts evolves from the Stokes-Einstein equation and Sutherland-Einstein equation to the Eyring equation with increasing pressure. And the key to obtain self-diffusion coefficient from shear viscosity under difference pressures is to determine A. in the Eyring equation. For Si~(4+) and O~(2-), this could be done using the linear relationship between A, and NBO% in anorthite melts. However, this method is inapplicable in other kinds of melts.