Effect of Hydrogen Bonding on the Compressibility of Chondrodite and Clinohumite

地球上相当一部分的水可能保存在地幔中矿物的原子结构中。以羟基离子（OH-）或分子水（H2O）形式存在的结构结合水可以降低岩石的融化温度，影响火山活动的特征，甚至可能产生引起地震的力量。因此，了解水（氢）如何在代表地幔的压力-温度条件下影响含水矿物的性质是很重要的。随着高压中子设备的发展，可以从小体积（90mm3）粉末样品中获得地幔压力下氢行为的原子级信息。使用这种技术研究的大多数矿物都具有相对简单的原子结构。在这个项目中，将首次使用同一样品收集的中子和x射线数据获得结构复杂矿物（腐殖质）的高压数据。x射线可以提供这些结构中较重的原子（金属和氧）所需要的精度。中子可以用来确定氢原子的位置。利用这些补充测量，应该有可能提高实验的准确性和精度，并更多地了解高压下氢原子环境的变化如何影响这些矿物的压缩。在相关的实验中，将收集humite矿物的红外光谱，并与氢原子环境中的中子数据进行对比。目的是利用腐殖质的原子结构作为模型，了解微量氢在橄榄石（地幔中的主要矿物）中的结合模式。

LagerEAR-0073734A significant portion of our planet's water may be held within the atomic structures of minerals in the mantle. The presence of structurally-bound water in the form of hydroxyl ion (OH-) or molecular water (H2O) can lower the melting temperatures of rocks, affect the character of volcanic activity and may even generate the forces that cause earthquakes. Therefore, it is important to understand how water (hydrogen) affects the properties of hydrous minerals at pressure-temperature conditions representative of the mantle. With the recent development of high-pressure, neutron facilities, atomic-level information on the behavior of hydrogen at mantle pressures can be obtained from small-volume (90 mm3), powdered samples. The majority of minerals that have been studied using this technique have relatively simple atomic structures. In this project, high-pressure data will be obtained for the first time on structurally-complex minerals (humites) using both neutron and X-ray data collected for the same sample. X-rays will give the precision required for the heavier atoms (metals and oxygen) in these structures. Neutrons can then be used to determine the hydrogen-atom positions. Using these complementary measurements, it should be possible to improve both the accuracy and precision of the experiments and learn more about how changes in the hydrogen-atom environment at high pressure affect the compression of these minerals. In a related experiment, infrared spectra will be collected for humite minerals and correlated to neutron data on the hydrogen-atom environment. The objective is use the atomic structure of humite as a model to understand the mode of incorporation of trace amounts of hydrogen in olivine, the predominant mineral in the mantle.