Predicting the structure and stability of titanium oxide electrides

Zhao

et al. 2021

Advcd Theory and Sims

Bi2O2X and Bi2OX2 (X = S, Se, and Te) have shown potential for thermoelectric, optoelectronic, etc. applications. The ground‐state structures of Bi2O2X have been determined experimentally (in space group I4/mmm). However, for Bi2OX2, only Bi2OS2 has been synthesized in the experiment (in space group P4/nmm). In previous theoretical studies, the crystal structures of Bi2OSe2 and Bi2OTe2 are assumed the same as that of Bi2OS2. Whether they can be experimentally synthesized remains an open question. Here, a swarm intelligence‐based structural prediction is employed in combination with first‐principles calculations to predict the crystal structures of Bi2OSe2. Three thermodynamically stable low‐energy phases (P21/m, P4/nmm, and P21/m′) are identified. Importantly, the newly reported P21/m phase, instead of the previously assumed P4/mmm phase, has the lowest energy. The P21/m‐Bi2OSe2 shows marginal stability with respect to decomposition into binary compounds Bi2O3 and Bi2Se3. The predicted phases of Bi2OSe2 have bandgaps of 0.67–1.19 eV and comparable small electron and hole carrier effective mass (less than 0.65 m0). The different phase stability between Bi2OSe2 and Bi2OS2 are explained in terms of different Bi─S and Bi─Se covalent bonding characters. Our work provides theoretical guidance for discovering new phases of Bi2OSe2 and an in‐depth understanding of the structure‐property relationship of Bi─O─S/Se system.

Section: Resultssupporting

confidence: 69%

Discovery of New Phases of Bismuth Oxyselenide Semiconductor Bi₂OSe₂ by Global Structure Search Approach

Zhao

et al. 2021

Advcd Theory and Sims

Acta Crystallogr B Struct Sci Cryst Eng Mater

“…164), or in the Ti 3 O Cmmm (No. 65) space groups (Zhong et al, 2018), as in our sulfur-rich Ti oxides.…”

Section: Summary Of the Crystal Structures Phase Transitions And Electronic Properties Of Mixed Tio 2 /Tis 2 Compoundsmentioning

confidence: 71%

Anion substitution and influence of sulfur on the crystal structures, phase transitions, and electronic properties of mixed TiO₂/TiS₂ compounds

Jovanović¹,

Zagorac²,

Matović³

et al. 2021

Recent studies of TiO2/TiS2 nanostructures with various morphologies have been reported, usually showing improved properties with applications from electronics and catalysis to solar cells and medicine. However, there is a limited number of studies on the crystal structures of TiO2/TiS2 compounds with corresponding properties. In this research, relevant crystal structures of TiO1–x S x (x = 0, 0.25, 0.5, 0.75 and 1) solid solutions were investigated using an ab initio method. For each composition, crystal structures adopting anatase, rutile and CdI2 structure type were calculated on LDA-PZ and GGA-PBE levels of theory. Novel phase transitions and predicted structures are presented, and apart from several interesting metastable structures, a very interesting pressure-induced phase transition is found in the TiOS compound. Furthermore, electronic properties were studied through the dependence of semiconducting properties on dopant concentration. The first description of the electronic properties of the mixed TiO1–x S x compounds in crystal form has been presented, followed by a detailed study of the structure–property relationship, which will possibly have numerous industrial and technological applications.

“…However, such a feature can be observed in some well‐known electrides, e.g. Y 5 Si 3 , [ 8b ] Ti 2 O, [ 17 ] YCl, and Y 2 Cl 3 . [ 9c ] This phenomenon can be regarded as a consequence of the mixing of the states of electride and metallic bonding.…”

Section: Resultsmentioning

confidence: 99%

Discovery of Electrides in Electron‐Rich Non‐Electride Materials via Energy Modification of Interstitial Electrons

Блатов

2022

Adv Funct Materials

With the discovery of electrides, many electron-rich materials are reported to be non-electrides due to the lack of electride characteristics. Up to date, only a few studies have been done to alter the electronic structures of these materials. In this work, through atom replacement, the energy of interstitial electrons in a non-electride Hf 5 Si 3 is successfully modified and a hitherto unknown electride Ca 3 Hf 2 Si 3 is obtained. It is revealed that the formation of the electride has a strong link to the neighboring cations of interstitial electrons. Moreover, an essential principle for the electride formation in the multi-cations materials is proposed, and 34 dynamically stable ternary electrides are obtained through the proper atom replacement in 29 binary non-electrides materials. The general realization of electrides in the electronrich non-electrides can greatly expand the research scope of electrides.