Chemistry dependence of the grain boundary character distribution (GBCD) of olivine

晶界特征分布（GBCD）是不同晶界的固有频率的量度;对于没有晶体择优取向的多晶体，它是各向异性和尺度不变的。基于这些观察，得出的结论是，GBCD是一个内在的参数有关的晶体结构。GBCD给出了描述晶界几何形状所需的全部5个参数，与晶界能相关。多晶材料的性能受到其内部界面网络的强烈影响。这是因为晶界的性质与理想晶格的性质显著不同。例如，不相容的元素可以存储（隔离）在晶界平面上，元素扩散是数量级快沿着晶界比通过晶格。这些化学杂质也影响晶界能、晶界迁移率及其强度。对橄榄石聚集体的初步测量也表明了GBCD的化学依赖性。基于这些有希望的初步结果，我建议调查的化学变化（包括熔体的存在）的橄榄石的GBCD的效果。这些数据是迫切需要量化晶界控制过程中橄榄石为主的岩石，他们可以，例如，解释变形实验中的巨大差异，似乎与材料的纯度。与计划的研究将解决以下问题：（iv） 晶界平面频率取决于化学环境吗？a. 晶界频率是否随相对不相容元素的加入而变化？B. 在熔体存在下晶界频率会改变吗？（五） 哪些是需要深入研究的重要晶界？（六） 在GBCD的变化影响激活不同的变形机制，如变形中的扩散调节晶界滑动制度？

The grain boundary character distribution (GBCD) is a measure of the natural frequency of different grain boundaries; it is anisotropic and scale invariant for polycrystals without crystal preferred orientations. Based on these observations it was concluded that the GBCD is an intrinsic parameter related to the crystal structure. The GBCD gives the full 5 parameters needed to describe the geometry of a grain boundary, related to the grain boundary energy. Properties of polycrystalline materials are strongly influenced by the network of their internal interfaces. This is because the properties of grain boundaries differ significantly from those of the ideal crystal lattice. For example, incompatible elements can be stored (segregated) on the grain boundary planes and element diffusion is orders of magnitude faster along grain boundaries than through the crystal lattice.Various studies show that the GBCD changes with chemistry of the grain boundaries and modifications are readily observed at concentrations below one wt.%. These chemical impurities also influence the grain boundary energy, grain boundary mobility and its strengths.Preliminary measurements on olivine aggregates also show a chemical dependence of the GBCD. Based on these promising preliminary results, I propose to investigate the effect of chemical variation (including the presence of melt) on the GBCD of olivine. Such data are urgently needed to quantify grain boundary controlled processes in olivine dominated rocks, they may, for example, explain the large discrepancies in deformation experiments that seem to correlate with the materials purity.With the planned research the following questions will be addressed: (iv) Do grain boundary plane frequencies depend on the chemical environment?a. Do grain boundary frequencies vary with the addition of relatively incompatible elements to the aggregate?b. Do grain boundary frequencies change in the presence of melt?(v) Which are the important grain boundaries to be studied in depth? (vi) Do changes in the GBCD affect the activation of different deformation mechanisms, such as deformation in the diffusional accommodated grain boundary sliding regime?