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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Pseudomorphic 2A → 2M → 2H phase transitions in lanthanum strontiumgermanate electrolyte apatites
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Pseudomorphic 2A → 2M → 2H phase transitions in lanthanum strontiumgermanate electrolyte apatites

机译：锗酸锶锶电解质磷灰石中的假晶2A→2M→2H相变

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Apatite-like materials are of considerable interest as potential solid oxide fuel cell electrolytes, althoughtheir structural vagaries continue to attract significant discussion. Understanding these features iscrucial both to explain the oxide ion conduction process and to optimise it. As the composition ofputative P6,/ m apatites with ideal formula [A'4][A"6][(B04)6][n is varied the [A14(B04)6] frameworkwill flex to better accommodate the [A"6X2] tunnel component through adjustment of the A'06metaprism twist angle (0). The space group theory prescribes that framework adaptation during phasechanges must lead to one of the maximal non-isomorphic subgroups of P6,/m (P2,, P2, / m, P1). Theseadaptations correlate with oxygen ion conduction, and become crucial especially when the tunnels arefilled by relatively small ions and/or partially occupied, and if interstitial oxygens are located in theframework. Detecting and completely describing these lower symmetry structures can be challenging,as it is difficult to precisely control apatite stoichiometry and small departures from the hexagonalmetric may be near the limits of detection. Using a combination of diffraction and spectroscopictechniques it is shown that lanthanum strontium germanate oxide electrolytes crystallise as triclinic (A),monoclinic (M) and hexagonal (H) bi-layer pseudomorphs with the composition ranges:[Lai, Sr,][(Ge04),,,,2(Ge0,),_,,,,][02] (0 < x < 1) apatite-2A [La,0_,S1',][1Ge04/5,,/2(Ge05)1-,/21[02] (1 < x < 2) apatite-2M [La,,,Sr,][(Ge04)6]10,1[H,] (2
机译：磷灰石样材料作为潜在的固体氧化物燃料电池电解质备受关注，尽管其结构上的变化不断引起人们广泛的讨论。理解这些特征对于解释氧化物离子传导过程和对其进行优化都是至关重要的。随着具有理想分子式[A'4] [A“ 6] [（B04）6] [n的推定P6 / m磷灰石的组成变化，[A14（B04）6]骨架将弯曲以更好地适应[A” 6X2通过调整A'06介电扭曲角（0）来确定隧道组件。空间群理论规定，相变期间的框架适应必须导致P6，/ m（P2 ,, P2，/ m，P1）的最大非同构子群之一。这些适应性与氧离子传导相关，并且变得尤为重要，特别是当隧道被相对较小的离子填充和/或被部分占据时，以及如果间隙氧位于框架中时。检测并完整描述这些较低的对称结构可能具有挑战性，因为很难精确控制磷灰石的化学计量，并且与六边形的微小偏差可能接近检测极限。使用衍射技术和光谱技术的组合表明，锗酸镧锶氧化物电解质结晶为三斜晶系（A），单斜晶系（M）和六边形（H）双层伪晶，其组成范围为：[Lai，Sr，] [（Ge04 ）,,,, 2（Ge0，），_ ,,,] [02]（0

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