Crystal Chemistry of Hydroxyl in Silicates

硅酸盐中羟基的晶体化学

• 批准号: 9526916
• 负责人: Joseph Smyth
• 金额: $ 9.6万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-01-01 至 1998-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9526916&HistoricalAwards=false
• 关键词: Crystal; Chemistry; Hydroxyl; Silicates

9526916 Smyth The proposed research is to investigate the crystal chemistry of hydroxyl substitution in a group of representative silicates. Several mineral structures will be refined by x-ray and/or neutron single crystal methods at various temperatures in order to test critical aspects of an electrostatic model for prediction of physical and chemical properties of hydroxyl-bearing silicates. H positions determined by x-ray and neutron diffraction will be compared to see if systematic differences are present that would allow use of x-ray data to estimate proton positions. Electrostatic site potentials will be computed for both x-ray and neutron h positions to see if systematic relations exist with IR data, relative thermal expansion of various nearest neighbor distances, 18O/18O and D/H fractionation and chemical weathering rates. These studies will hopefully improve the predictive capability for physical and chemical properties of hydroxyl-bearing silicates and may yield a constraint on the H flux returning into the mantle.

9526916 Smyth拟议的研究是为了研究一组具有代表性的硅酸盐中羟基取代的晶体化学。几种矿物结构将通过X射线和/或中子单晶法在不同的温度下进行精炼，以测试用于预测含羟基硅酸盐的物理化学性质的静电模型的关键方面。将对X射线和中子衍射确定的氢位置进行比较，以确定是否存在系统差异，从而允许使用X射线数据来估计质子位置。将计算x射线和中子h位置的静电位点势，以查看是否存在与IR数据、各种近邻距离的相对热膨胀、18O/18O和D/H分馏以及化学风化速率之间的系统关系。这些研究有望提高对含羟基硅酸盐物理化学性质的预测能力，并可能对返回地幔的氢通量产生限制。