Search for: All records

This study investigates the facile hydride synthesis method guided by theoretical predictions to explore the K–T–Bi (T = Zn, Cd) phase spaces. Using an adaptive genetic algorithm (AGA) and density functional theory (DFT), candidate compositions are identified for experimental validation via a facile hydrides route, permitting experimental screening of K–Zn–Bi and “empty” K–Cd–Bi systems. The previously reported KZnBi and KZn₂Bi₂are synthesized alongside newly discovered KCdBi and KCd₂Bi₂. While the AGA and DFT predict the stability of these compounds, structural predictions align with the experiment only for KZnBi and KZn₂Bi₂. Single‐crystal X‐ray structure refinements confirm that KZnBi and KZn₂Bi₂adopt the hexagonal ZrBeSi‐ and tetragonal ThCr₂Si₂‐structure types, respectively. KCdBi has tetragonal PbClF‐structure type and KCd₂Bi₂belongs to the ThCr₂Si₂‐structure type. A trend based on the ratio of the metal ionic radii allows to rationalize variation in the structure types within theATBi family (A = Li–Cs), correctly identifying KCdBi as isostructural to NaZnBi. Thermal stability studied by high‐temperature powder X‐ray diffraction reveals that Zn‐containing compounds melt at higher temperatures (821 K for KZn₂Bi₂) than Cd‐containing KCd₂Bi₂(635 K). This study highlights the efficacy of combining rapid synthesis techniques with predictive modeling, though structural predictions show some limitations in accuracy. 

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” Na−Zn−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 Na₁₁Zn₂Bi₅(Na₁₁Cd₂Sb₅type,P) phases were successfully synthesized, while other computationally generated compounds on the list were rejected. In addition, single crystal X‐ray 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‐situsynchrotron powder X‐ray diffraction studies shed light on complex equilibria in the Na−Zn−Bi system at elevated temperatures. In particular, the high‐temperature polymorphHT‐Na₃Bi (BiF₃type,Fmm) was obtained as a product of Na₁₁Zn₂Bi₅decomposition above 611 K.HT‐Na₃Bi cannot be stabilized at room temperature by quenching, and this type of structure was earlier observed in the high‐pressure polymorphHP‐Na₃Bi above 0.5 GPa. The aforementioned approach of predictive synthesis can be extended to other multinary systems.