Data_Sheet_1_Exploration of Multi-Component Vanadium and Titanium Pnictides Using Flux Growth and Conventional High-Temperature Methods.pdf

The flux growth method was successfully employed to synthesize millimeter-sized single crystals of the ternary barium vanadium pnictides Ba5V12As19+x (x ≈ 0.02) and Ba5V12Sb19+x (x ≈ 0.36), using molten Pb and Sb, respectively. Both compositions crystallize in space group P4̄3m and adopt a structure similar to those of the barium titanium pnictides Ba5Ti12Pn19+x (Pn = Sb, Bi), yet with a subtly different disorder, involving the pnictogen and barium atoms. Attempts to obtain an arsenide analog of Ba5Ti12Pn19+x using a Pb flux technique yielded binary arsenides. High-temperature treatment of the elements Ba, Ti, and As in Nb or Ta tubes resulted in side reactions with the crucible materials and produced two isostructural compositions Ba8Ti13−xMxAs21 (M = Nb, Ta; x ≈ 4), representing a new structure type. The latter structure displays fcc-type metal clusters comprised of statistically distributed Ti and M atoms (M = Nb, Ta) with multi-center and two-center bonding within the clusters, as suggested by our first-principle calculations.

本研究采用助熔剂法（flux growth method），分别以熔融铅（Pb）和锑（Sb）作为助熔剂，成功合成了毫米级别的三元钒钡氮族化物Ba5V12As19+x（x≈0.02）与Ba5V12Sb19+x（x≈0.36）单晶。两种化合物均结晶于空间群P4̄3m，其晶体结构与钡钛氮族化物Ba5Ti12Pn19+x（Pn=Sb, Bi）的结构相似，但在氮族原子与钡原子的无序排布上存在细微差异。尝试采用铅助熔剂法制备Ba5Ti12Pn19+x的砷化物类似物，最终仅得到二元砷化物。将钡（Ba）、钛（Ti）与砷（As）单质置于铌（Nb）或钽（Ta）制成的管中进行高温处理时，发生了与坩埚材料的副反应，生成两种同构化合物Ba8Ti13−xMxAs21（M=Nb, Ta；x≈4），该体系代表一种全新的晶体结构类型。据我们的第一性原理计算（first-principle calculations）结果显示，该新型结构呈现面心立方（fcc）型金属团簇，团簇内的Ti与M原子（M=Nb, Ta）呈统计分布，团簇内部存在多中心键与双中心键相互作用。