How to Look for Compounds: Predictive Screening and in situ Studies in Na−Zn−Bi System

Abstract

Here, the combination of theoretical computations followed by rapid experimental screening and in situ diffraction studies is demonstrated as a powerful strategy for novel compounds discovery. When applied for the previously "empty" NaÀ ZnÀ Bi system, such an approach led to four novel phases. The compositional space of this system was rapidly screened via the hydride route method and the theoretically predicted NaZnBi (PbClF type, P4/nmm) and Na 11 Zn 2 Bi 5 (Na 11 Cd 2 Sb 5 type, P � 1) phases were successfully synthesized, while other computationally generated compounds on the list were rejected. In addition, single crystal Xray diffraction studies of NaZnBi indicate minor deviations from the stoichiometric 1 : 1 : 1 molar ratio. As a result, two isostructural (PbClF type, P4/nmm) Zn-deficient phases with similar compositions, but distinctly different unit cell parameters were discovered. The vacancies on Zn sites and unit cell expansion were rationalized from bonding analysis using electronic structure calculations on stoichiometric "NaZnBi". In-situ synchrotron powder X-ray diffraction studies shed light on complex equilibria in the NaÀ ZnÀ Bi system at elevated temperatures. In particular, the high-temperature polymorph HT-Na 3 Bi (BiF 3 type, Fm � 3m) was obtained as a product of Na 11 Zn 2 Bi 5 decomposition above 611 K. HT-Na 3 Bi cannot be stabilized at room temperature by quenching, and this type of structure was earlier observed in the high-pressure polymorph HP-Na 3 Bi above 0.5 GPa. The aforementioned approach of predictive synthesis can be extended to other multinary systems. This method has been successfully applied to prepare several complex materials, including ternary borides, antimonides, arsenides, silicides, and germanides, where comprehensive control over composition is crucial for the targeted preparation

Mechanistically Guided Materials Chemistry: Synthesis of Ternary Nitrides, CaZrN2 and CaHfN2

“…Predictive synthesis remains an important goal for materials chemists. − While many joint computational-experimental synthesis efforts have been reported in literature, − trial-and-error approaches remain the dominant paradigm. Within this current paradigm, in situ X-ray diffraction (XRD) is a powerful technique for materials discovery. ,− Sometimes called “panoramic synthesis,” − , in situ X-ray diffraction allows for observation of solid-state reactivity as it happens.…”

Crystal and Electronic Structure of Ternary Bismuthides BaTM1.8Bi2 (TM = Au, Ag) with a New Variation of the BaAu2Sb2 Structure Type

“…Complex pnictides of d-metals have long been the focus of researcher's attention due to the diversity of their structures combined with interesting physical properties [1][2][3][4][5][6]. The discovery of superconductors based on layered ferroarsenides in 2008 caused great interest in the scientific community and stimulated the search for analogues of these compounds.…”

Synthesis and crystal growth of novel layered bismuthides ATM2Bi2 (A=K, Rb, Cs; TM=Zn, Cd), electron‐deficient compounds with the ThCr2Si2 structure

“…The former turned out to be isostructural to the 111 Fe‐based superconductors, whereas the latter crystallizes in a different space group [18] . After some time, the compound NaZnBi was obtained independently, [19] and the authors [19] concluded that there was a certain zinc deficiency in its structure. It is interesting to note that the synthesis of compounds Na TM Bi ( TM =Zn, Cd) confirmed the theoretical prediction of their existence, although the observed crystal structure was found to be different [20–22] …”