Formation and Elimination of Anti-site Defects during Crystallization in Perovskite Ba1–xSrxLiF3
Formation and Elimination of Anti-site Defects during Crystallization in Perovskite Ba1–xSrxLiF3
复制标题
钙钛矿 Ba1âxSrxLiF3 结晶过程中反位点缺陷的形成与消除
DOI：
10.1021/acs.cgd.7b01552
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发表时间：
2018
影响因子：
3.8
通讯作者：
D.C. Sayle
中科院分区：
文献类型：
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作者：
A. Düvel;L.M. Morgan;C.V. Chandran;P. Heitjans;D.C. Sayle
材料的缺陷密度对其物理、化学和机械性能起决定性作用。因此，对于电池、燃料电池、电子、光学、催化以及机械强度和弹性等应用来说，缺陷调谐是可取的。在高能球磨过程中，我们通过用srlif3纳米颗粒压缩balif3纳米颗粒来模拟钙钛矿ba1 - xsrxlif3的机械化学合成。研究了该体系的结晶过程和离子迁移率，并与实验结果进行了比较。在高压下模拟结晶的动画显示，在结晶前沿的阳离子通常会凝结到“不正确的”点阵位置，在某些情况下最终导致反点阵缺陷的形成。然而，这些阳离子中的大多数会重新定型，而“正确的”阳离子会取代它的位置——纠正缺陷。至关重要的是，非晶/晶体界面使这种修复成为可能，因为离子在该区域是可移动的。模拟结果表明，在BaLiF3的反位缺陷区和其他缺陷区附近离子迁移率高，而在无缺陷区离子迁移率低。MD模拟表明，高能球磨可以通过将这些缺陷暴露在表面或在晶体内产生非晶态区域来降低材料中的反位缺陷密度，从而允许局部再结晶，从而实现缺陷修复。这一假设可能解释了核磁共振光谱所揭示的离子迁移率降低的原因，因此，与热合成的balif3样品相比，高能球磨制备的balif3很可能缺陷密度更小。
The defect density of a material is decisive for its physical, chemical, and mechanical properties. Accordingly, defect tuning is desirable for applications spanning, e.g., batteries, fuel cells, electronics, optics, catalysis, and mechanical strength and resilience. Here, we simulate the mechanochemical synthesis of the perovskite Ba1–xSrxLiF3by compressing a BaLiF3nanoparticle with a SrLiF3nanoparticle under conditions likely to occur during high-energy ball milling. We investigate the crystallization process and the ionic mobility of the system and compare with experiment. Animations of the crystallization, simulated under high pressure, revealed that cations, within the crystallization front, would commonly condense onto “incorrect” lattice sites, in some cases eventually leading to the formation of anti-site defects. However, most of these cations would then re-amorphize and the “correct” cation would take its place—rectifying the defect. Crucially, it is the amorphous/crystalline interface that enables such repair because the ions are mobile in this region. The simulations reveal high ion mobility close to the anti-site defects and other defective regions, but no ion mobility in the defect free regions of BaLiF3. The MD simulations indicate that high-energy ball milling might reduce the anti-site defect density in a material by exposing these defects to the surface or creating amorphous regions within the crystallite which then would allow localized recrystallization, enabling defect repair. This assumption is a possible explanation for the reduced ion mobility, revealed by NMR spectroscopy, and, thus, most likely smaller defect density in BaLiF3prepared by high-energy ball milling compared to thermally synthesized BaLiF3samples.
关于 BaLiF3 离子电导率的机制：分子动力学研究。
DOI：
--
发表时间：
2011
期刊：
Physical Chemistry, Chemical Physics - PCCP
影响因子：
--
作者：
D. Zahn;S. Herrmann;P. Heitjans
通讯作者：
P. Heitjans