Outliers in Shannon’s effective ionic radii table and the table extension by machine learning

Alsalman, Mohammed; Alghofaili, Yousef A.; Baloch, Ahmer A.B.; Alsadah, Haydar; Alsaui, Abdulmohsen A.; Alqahtani, Saad M.; Muqaibel, Ali H.; Alharbi, Fahhad H.

doi:10.1016/j.commatsci.2023.112350

Cited by 3 publications

(1 citation statement)

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“… Table lists the tolerance factors for various AMN 2 nitride compositions as well as KCoO 2 and α-NaFeO 2 for comparison. Because many ion radii are unavailable in the original Shannon’s data, the cationic sizes used for the tolerance factor calculations are from the updated Shannon effective ionic radii by machine learning. , Compared to the original Shannon’s ionic radii, the reliability of the machine learned radii is proven by the tiny error. For example, the machine learned ionic radius of the Ti 4+ ion for 5-coordination is 0.5129 Å with respect to 0.51 Å of the original proposed ionic radii by Shannon.…”

Section: Resultsmentioning

confidence: 99%

Tolerance Factor and Phase Stability of the KCoO₂-Type AMN₂ Nitrides

Shang,

Feng,

Zhang

et al. 2024

Inorg. Chem.

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In order to help understand the structural stability of KCoO 2 -type ternary nitrides AMN 2 , referring to perovskite structure, a tolerance factor t is proposed to describe the size effect on the phase/symmetry options of the experimentally accessible AMN 2 nitrides. This leads to a range of t values above 0.946 for structurally stable KCoO 2 -type AMN 2 nitrides with t values around 0.970 for the orthorhombic and tetragonal phase boundary. In contrast, most of AMN 2 nitrides exhibit α-NaFeO 2 -type structure with t ∼ 0.898−0.946 and cations ordered or disordered rocksalt structure while t below 0.898. Employing the proposed criterion, the structure formation for other ternary AMN 2 compositions with lanthanum and alkaline earth cations for the A sites were predicted, which was testified through the synthesis attempts and complemented by formation energy evaluations. The efforts to synthesize the ternary Lanthanide and alkaline earth-based AMN 2 nitrides were unsuccessful, which could associate the structural instability with the large formation energies of lanthanide nitrides LaMN 2 and the greater tolerance factor of 1.048 for BaTiN 2 . The experimentally already synthesized AMN 2 nitrides could be categorized into three types with different tolerance factors, and scarce AMN 2 nitrides with lower formation energies would be accessible using different synthetic routes beyond the traditional solid-state synthesis method.

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