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首页> 外文期刊>Zeitschrift fur Anorganische und Allgemeine Chemie >Synthesis of a new modification of lithium chloride confirming theoretical predictions
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Synthesis of a new modification of lithium chloride confirming theoretical predictions

机译：新型氯化锂的合成证实了理论预测

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In accordance with prior calculations, the new polymorph β-LiCl (wurtzite structure type) has been synthesised, by the low-temperature atomic-beam-deposition (LT - ABD) technique, in a mixture with α-LiCl (rock salt structure type) by depositing LiCl vapour (2 to 5.3 × 10 ~(-4)mbar) onto a cooled substrate (-30 to -60 °C). The maximum β-LiCl fraction of 53 % was obtained using a sapphire (0001) substrate at -50 °C and 3.7 × 10~(-4)mbar LiCl vapour pressure. The proportion of the new polymorph contained in the bulk sample decreases as temperature or vapour pressure deviate from these values, until finally the rock salt type LiCl is found exclusively. When the samples are warmed up to room temperature, β-LiCl irreversibly transforms to α-LiCl. The X-ray diffraction pattern of the two phase LiCl sample measured at -50 °C has been indexed and refined based on a hexagonal unit cell for β-LiCl with the lattice constants a = 3.852(1) ? and c = 6.118(1) ? and a cubic unit cell for α-LiCl with the lattice constant a = 5.0630(8) ?. By Rietveld refinement the wurtzite type of structure (P6_3mc, No. 186) was suggested for the new hexagonal modification of LiCl with the Li - Cl distances (2.32 and 2.34 ?) being 8 % smaller than those of α-LiCl. Moreover, the cell volume decreases as much as 16 % during the transition from β-LiCl to α-LiCl. Both the shifts in bond lengths and volume correspond well with the situation encountered for LiBr and LiI. Besides the variation of LiCl vapour pressure and substrate temperature, also different substrate materials were employed for testing their influence on formation of the β-LiCl polymorph.
机译：根据先前的计算，通过低温原子束沉积（LT-ABD）技术，在与α-LiCl（岩盐结构类型）的混合物中合成了新的多晶型物β-LiCl（纤锌矿结构类型） ）将LiCl蒸气（2至5.3×10〜（-4）mbar）沉积在冷却的基板（-30至-60°C）上。使用蓝宝石（0001）衬底在-50°C和3.7×10〜（-4）mbar LiCl蒸气压下获得的最大β-LiCl分数为53％。随着温度或蒸气压偏离这些值，新样品中所含新多晶型物的比例会降低，直到最终仅发现岩盐型LiCl。将样品加热到室温后，β-LiCl不可逆地转变为α-LiCl。基于六边形晶胞的β-LiCl晶格常数a = 3.852（1）？，在六角形晶胞上对在-50°C下测得的两相LiCl样品的X射线衍射图进行了索引和优化。和c = 6.118（1）？ α-LiCl的立方晶胞，晶格常数为a = 5.0630（8）。通过Rietveld改进，提出了纤锌矿型结构（P6_3mc，编号186）用于LiCl的新型六边形修饰，其Li-Cl间距（2.32和2.34？）比α-LiCl的间距小8％。此外，在从β-LiCl过渡到α-LiCl的过程中，电池体积减少了16％。键长和体积的变化都与LiBr和LiI遇到的情况非常吻合。除了改变LiCl蒸气压和基材温度外，还采用了不同的基材材料来测试其对β-LiCl多晶型物形成的影响。

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