Phase Selectivity and Stability in Compositionally Complex Nano (nA1/n)Co2O4
Phase Selectivity and Stability in Compositionally Complex Nano (nA1/n)Co2O4
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DOI：
10.1021/acs.chemmater.3c01647
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发表时间：
2023-08
影响因子：
8.6
通讯作者：
Xin Wang;Peter C. Metz;E. Calì;P. R. Jothi;E. Lass;K. Page
中科院分区：
文献类型：
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作者：
Xin Wang;Peter C. Metz;E. Calì;P. R. Jothi;E. Lass;K. Page
采用低温软模板法合成了一组复合尖晶石，分子式为（nA1/n）Co2O4（A = Mg、Cr、Mn、Fe、Co、Ni、Cu和Zn的组合）。发现该系列的相选择性和温度稳定窗口强烈地依赖于a位的组成，而仅适度地依赖于a位上存在的元素数量(n)。选择控制反应和原位高温x射线衍射（XRD）发现了温度激活脱混对含有Mg， Ni， Mn和Fe成分的倾向。扫描透射电子显微镜（STEM）、能谱分析（EDS）和x射线谱分析表明，a位阳离子在形成尖晶石中的空间分布呈非均匀分布，随着中间热处理的进行，a位阳离子逐渐减少。得到的单尖晶石相是亚稳的，在高温退火后分离成杂质相和多尖晶石相的混合物。此外，我们证明了组成复杂的氧化物结构的“连续晶格”参数化提供了一种快速的方法，通过全剖面细化来检查阳离子分布的非均质性。这些组成复杂的尖晶石中阳离子分布或聚类的可调性通过热力学杠杆为功能材料的合理设计提供了有趣的机会。
A family of compositionally complex spinels with the formula(nA1/n)Co2O4(A = combinations of Mg, Cr, Mn, Fe, Co, Ni, Cu, and Zn) was synthesized using a low-temperature soft-templating method. The phase selectivity and the temperature stability window for the series were found to depend strongly upon the A-site composition and only modestly on the number of elements (n) present on the A-site. Select control reactions and in situ high-temperature X-ray diffraction (XRD) uncovered a propensity for temperature-activated de-mixing for compositions containing Mg, Ni, Mn, and Fe. The A-site cations exhibit spatially heterogeneous distributions in the as-formed spinels, which diminish with intermediate thermal annealing, as shown by scanning transmission electron microscopy (STEM)/energy dispersive spectroscopy (EDS) and X-ray line profile analysis. The single spinel phases obtained are metastable, separating into a mix of impurity phases and multiple spinel phases with higher temperature annealing. Furthermore, we demonstrate that a “continuous lattice” parameterization of the compositionally complex oxide structure provides a rapid means by which to examine the heterogeneity of the cation distribution through full profile refinement. The demonstrated tunability of the cation distribution or clustering in these compositionally complex spinels via thermodynamic levers affords interesting opportunities for rational design of functional materials.