Crystal chemistry of hibonite as indicator for oxygen fugacities during solar nebula condensation

富含钙铝的包裹体（CAIs）产生了太阳系固体中最古老的测量年龄，因此可以提供有关早期太阳星云温度和氧逸度条件的重要信息。在几个CAIs中存在的矿物黑云母是来自太阳星云的初级冷凝物之一，并且含有大量不同氧化还原状态的Ti。因此，它是一个理想的候选人提供洞察早期太阳系的氧逸度。到目前为止进行的实验表明，钛的氧化态不仅取决于氧逸度，在黑云母形成，但也对它的晶体化学。因此，需要在不同温度和氧逸度下进一步合成具有不同Ti、Mg和V含量的Hibonite，以获得用于Hibonite的氧气压计。在hibonite的阳离子分布将获得单晶结构的细化，而EELS光谱的合成hibonites将仔细分析，以获得信息的钛的氧化态和其阳离子分布。我们希望，我们的研究将是必不可少的约束复杂的历史的冷凝和蚀变的陨石灰岩从不同类型的陨石，也将使用相同的技术进行分析。

Calcium-aluminium-rich inclusions (CAIs) yield the oldest measured ages of any solar system solid and as such can give essential information on the temperature and oxygen fugacity conditions of the early solar nebula. The mineral hibonite, present in several CAIs, is one of the primary condensates from the solar nebula and contains significant amounts of Ti in different redox states. It is therefore an ideal candidate for providing insight into the oxygen fugacity of the early solar system. Experiments conducted so far reveal that the oxidation state of Ti does not depend solely on the oxygen fugacity at which hibonite is forming, but also on its crystal-chemistry. Further syntheses of hibonites with different Ti, Mg and V contents at different temperatures and oxygen fugacities are therefore necessary to obtain an oxygen barometer for hibonite. Cation distribution in hibonite will be obtained by single-crystal structural refinements, whereas EELS spectra of synthetic hibonites will be carefully analysed in order to obtain information both on the Ti oxidation state and on its cation distribution. We expect that our study will be essential for constraining the complex history of condensation and alteration of meteoritic hibonites from different types of chondrites which will be also analysed using the same techniques.