Paolo Ballirano, Beatrice Celata, Alessandro Pacella, Andrea Bloise, Ferdinando Bosi
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引用次数: 0
Abstract
A series of Li+/Fe3+-doped enstatite crystals of composition Mg(2-2x)LixFexSi2O6 were synthesized and structurally characterized. Under the selected experimental conditions, we grew three crystals of Pbca orthopyroxene (OPX: x = 0.270-0.313) and two crystals of Pbcn protopyroxene (PPX: x = 0.156-0.164) using the flux-growth technique. The observed variation in the polyhedral volume and distortion of the M2 octahedron as a function of Li/Fe3+ doping suggests the presence of an upper limit, at least for the OPX samples. The same linear relation was observed between the polyhedral volume and ⟨M1-O⟩ bond length across all analysed samples, including the endmembers protoenstatite (PEN), orthoenstatite (OEN) and LiFe3+Si2O6. It seems that the M2 octahedron plays a crucial role in stabilizing the pyroxene topology in either the PEN or the OEN form, because the PPX and OPX samples show two distinct linear relations between the M2O6 polyhedral volume and ⟨M2-O⟩, with the PPX trend converging toward the parameters of the LiFe3+Si2O6 endmember, whereas the OPX trend, including OEN, diverges largely from these parameters.
合成了一系列Li+/Fe3+掺杂的顽辉石晶体,组成为Mg(2-2x)LixFexSi2O6,并进行了结构表征。在选定的实验条件下,我们利用通量生长技术生长出了三颗Pbca正晶(OPX: x = 0.270-0.313)和两颗Pbcn原晶(PPX: x = 0.156-0.164)。观察到的M2八面体的多面体体积和畸变随Li/Fe3+掺杂的变化表明存在一个上限,至少对于OPX样品是如此。在所有分析样品中,包括端元原顽辉石(PEN)、正顽辉石(OEN)和LiFe3+Si2O6,多面体体积与< _1 - o >键长之间都观察到相同的线性关系。M2八面体似乎在稳定PEN或OEN形式的焦石拓扑结构中起着至关重要的作用,因为PPX和OPX样品在M2O6多面体体积和< M2- o >之间表现出两种明显的线性关系,PPX趋势向LiFe3+Si2O6端元的参数收敛,而OPX趋势,包括OEN,在很大程度上偏离这些参数。
期刊介绍:
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials publishes scientific articles related to the structural science of compounds and materials in the widest sense. Knowledge of the arrangements of atoms, including their temporal variations and dependencies on temperature and pressure, is often the key to understanding physical and chemical phenomena and is crucial for the design of new materials and supramolecular devices. Acta Crystallographica B is the forum for the publication of such contributions. Scientific developments based on experimental studies as well as those based on theoretical approaches, including crystal-structure prediction, structure-property relations and the use of databases of crystal structures, are published.