Sharma Shilendra Kumar, Chaudhary Vivek, Pala Raj Ganesh S, Sivakumar Sri
Materials Science Programme, Indian Institute of Technology, Kanpur, Uttar Pradesh, 208016, India.
Department of Chemical Engineering, Indian Institute of Technology, Kanpur, Uttar Pradesh, 208016, India.
Phys Chem Chem Phys. 2024 Aug 7;26(31):20837-20851. doi: 10.1039/d4cp02294g.
Non-native structures (NNS) differ in discrete translational symmetry from the bulk ground state native structure (NS). To explore the extent of deconvolution of various factors relevant to the stabilization of the wurtzite/NNS of MnSe a heat-up method, we performed experiments using various ligands (oleic acid, oleylamine, octadecylamine, stearic acid, and octadecene), solvents (tetraethylene glycol and octadecene), and precursor salts (manganese chloride and manganese acetate). Experiments suggest that oleic acid in the presence of tetraethylene glycol and oleylamine in the presence of octadecene stabilize wurtzite/NNS. Further, density functional theory (DFT) computations explore the interaction between the functional groups in ligands and the most exposed surfaces of wurtzite/NNS and rocksalt/NS polymorphs. Computations suggest that the interactions between relevant surface facets with carboxylic acid and the double bond functional groups suppress the phase transformation from NNS to NS. In addition, the ionizability of the precursor salt also determines the rate of formation of the metal-ligand complex and the rate of nucleation. Consequently, the formation rate of the Mn-ligand complex is expected to be greater in the case of chloride salt than acetate salt because the chloride salt has higher ionizability in ethylene glycol. From the above, we conclude that the kinetics of the wurtzite/NNS to rocksalt/NS phase transformation depends mainly on two factors: (1) nucleation/growth kinetics which is controlled by the ionizability of the precursor salt, solvent, and stability of the metal-ligand complex, and (2) the activation energy barrier of the NNS to NS conversion which is controlled by surface energy minimization with the ligand.
非本征结构（NNS）在离散平移对称性上与体相基态本征结构（NS）不同。为了探究与MnSe纤锌矿/NNS稳定性相关的各种因素的解卷积程度，我们采用升温法，使用各种配体（油酸、油胺、十八胺、硬脂酸和十八烯）、溶剂（四甘醇和十八烯）以及前驱体盐（氯化锰和醋酸锰）进行了实验。实验表明，在四甘醇存在下的油酸以及在十八烯存在下的油胺能够稳定纤锌矿/NNS。此外，密度泛函理论（DFT）计算探究了配体中的官能团与纤锌矿/NNS和岩盐/NS多晶型最暴露表面之间的相互作用。计算结果表明，相关表面晶面与羧酸和双键官能团之间的相互作用抑制了从NNS到NS的相变。此外，前驱体盐的电离能力也决定了金属 - 配体络合物的形成速率和成核速率。因此，由于氯化盐在乙二醇中的电离能力更高，预计在氯化盐的情况下Mn - 配体络合物的形成速率比醋酸盐的情况更大。综上所述，我们得出结论，纤锌矿/NNS到岩盐/NS相变的动力学主要取决于两个因素：（1）成核/生长动力学，它由前驱体盐的电离能力、溶剂以及金属 - 配体络合物的稳定性控制；（2）NNS到NS转变的活化能垒，它由配体使表面能最小化来控制。
