Effect of Hydrogen Bonding on the Compressibility of Chondrodite and Clinohumite

地球上很大一部分水可能存在于地幔矿物的原子结构中。以氢氧根离子（OH-）或分子水（H2O）形式存在的结构结合水可以降低岩石的熔化温度，影响火山活动的特征，甚至可能产生引起地震的力量。因此，重要的是要了解水（氢）如何影响含水矿物的性质在压力-温度条件下的地幔代表。随着最近高压中子设施的发展，氢在地幔压力下的行为的原子级信息可以从小体积（90立方毫米）的粉末样品中获得。使用这种技术研究的大多数矿物具有相对简单的原子结构。 在该项目中，将首次利用从同一样品收集的中子和X射线数据获得关于结构复杂矿物（腐殖土）的高压数据。X射线将提供这些结构中较重原子（金属和氧）所需的精确度。中子可以用来确定氢原子的位置。使用这些互补的测量，应该可以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。在一个相关的实验中，将收集腐殖酸矿物的红外光谱，并将其与氢原子环境的中子数据相关联。 目的是利用腐植岩的原子结构作为模型来理解地幔中主要矿物橄榄石中微量氢的结合方式。

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.