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首页> 外文期刊>The American mineralogist >Defect contributions to the heat capacities and stabilities of some chain, ring, and sheet silicates, with implications for mantle minerals
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Defect contributions to the heat capacities and stabilities of some chain, ring, and sheet silicates, with implications for mantle minerals

机译：缺陷对某种链条，环和硅酸盐的热量和稳定性的缺陷贡献，具有披风矿物的影响

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摘要

At temperatures less than similar to 1500 K, previously published C-P data demonstrate that the heat capacities of orthoenstatite, proto-enstatite, diopside, and pseudowollastonite include primarily Debye type vibrational and anharmonic contributions, whereas the alkali chain, sheet, and ring silicates, Na2SiO3, Li2SiO3, K2SiO3, and Na2Si2O5 include a third contribution. The third contribution to C-P arises from defect formation due to the mobility Na, K, Li, and O2-. The contribution becomes apparent at temperatures above 700-800 K for Na and K silicates, and above 900-1000 K for Li metasilicate. With strong thermal agitation, alkali-non-bridging oxygen (NBO) bonds are ruptured with the cations exiting their structural sites to occupy interstitial sites, thereby producing intrinsic Frenkel defects, which contribute to the C-P of the alkali silicates. The magnitudes of the C-P defect contributions correlate inversely with cation-oxygen bond strengths, as measured by bond dissociation energies. K-O and Na-O bond strengths are weak (239 and 257 kJ/mol) and defect contributions are large for these alkali chain, ring, and sheet silicates. The greater bond strength of Li-O (341 kJ/mol) correlates with a weaker defect contribution to the C-P of Li2SiO3. Mg-O and Ca-O bonds are stronger still (394 and 464 kJ/mol) and no C-P defect contributions are observed for the pyroxenes and pseudowollastonite up to similar to 1500 K.
机译：在温度低于1500 k的温度下，先前公布的CP数据表明，正交牙品，原山峰，缩孔和假旋属植物的热能主要包括Deyby型振动和无谐波贡献，而碱链，片材和环硅酸盐，Na2SiO3 ，Li2SiO3，K2SiO3和Na2Si2O5包括第三种贡献。由于迁移率Na，K，Li和O2-，对C-P的第三贡献产生缺陷形成。在Na和K硅酸盐的温度高于700-800k的温度下，贡献变得显而易见，并且对于Li偏离900-1000K以上。具有强烈的热搅拌，碱性非桥接氧（NBO）键与离开其结构部位的阳离子破裂以占用间质位，从而产生内在的弗雷塞缺陷，这有助于碱性硅酸盐的C-P.通过粘合解离能量测量，C-P缺陷贡献的幅度与阳离子粘合强度相反。 K-O和Na-O键合强度较弱（239和257 kJ / mol），这些碱链条，环和硅酸盐缺陷贡献很大。 Li-O（341 kJ / mol）的更大键合强度与Li2SiO3的C-P的缺陷贡献较弱。 Mg-O和CA-O键更强（394和464 kJ / mol），并且对于紫罗丁和伪动岩岩，不观察到C-P缺陷贡献，而Pseudowolastonite则与1500 k相似。

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