Kim, Dohyun Ye, Kun Hee Jeong, Taeyoung Yoon, Seungjae Kim, Yunjae Hwang, Cheol Seong Choi, Jung-Hae 2025-07-18T03:00:23Z 2025-07-18T03:00:23Z 2025-07-18 2025-07 1463-9076 https://pubs.kist.re.kr/handle/201004/152761 This study broadens the understanding of the crystalline structures of Ta2O5, renowned for its inherent adaptive characteristics, by a unified and systematic approach to reconstruct crystalline structures as polytypes. This approach is applied to the layered adaptive structure and the Wadsley-Roth crystallographic shear (CS) adaptive structure, which were conventionally considered separately. The lambda phase and the gamma phase are investigated as representative phases of each type of adaptive structure, respectively, and the newly proposed Pmma phase is also examined. Using glide or screw symmetry operations, the individual phase is decomposed into smaller structural units, enabling the construction of an infinite number of polytypic variants. These variants are categorized into distinct polytype families and integrated into a single schematic encompassing both layered and CS adaptive structures. First principles calculations reveal that energy differences between the polytypic variants are generally smaller than the thermal energy at ambient temperature, suggesting that various stacking sequences can appear experimentally. Dynamically, on the other hand, polytypic variants with regular and frequent alternations of the structural units are favorable. These theoretical predictions are supported by previous experimental observations of the orthorhombic low-temperature phase (L-Ta2O5) with various periodicities. The high-symmetry lambda and gamma phases are corroborated as benchmark phases within their respective polytype families. English Royal Society of Chemistry Polytype family representations of octahedrally coordinated adaptive structures in Ta2O5: energetic and dynamic stability from first principles Article 10.1039/d5cp01821h 1 Physical Chemistry Chemical Physics, v.27, no.26, pp.14082 - 14094 Physical Chemistry Chemical Physics 27 26 14082 14094 Y scie scopus 001513020000001 Chemistry, Physical Physics, Atomic, Molecular & Chemical Chemistry Physics Article ELECTRONIC-STRUCTURE CRYSTAL-STRUCTURE TEMPERATURE FORM OXYGEN VACANCY PHASE L-TA2O5 OXIDES SHEAR