Crystal and chemical anisotropy effects in AE2Zn2N2, (AE = Ca, Sr, Ba) from ab initio
Résumé
Crystal and chemical anisotropy effects in AE 2 ZnN 2 , (AE = Ca, Sr, Ba) from ab initio. Abstract: In the tetragonal ternary nitrides AE 2 ZnN 2 (AE = Ca, Sr, Ba), Zn has a rare linear coordination with nitrogen (N–Zn–N) along the c axis and N is located in an AE 5 Zn–like octahedron. Such features lead to original anisotropic crystal and chemical bond effects addressed herein with DFT-GGA based methods accounting for the cohesive energies, the energy volume equations of state EOS, the elastic constants and the properties of chemical bonding. Along AE = Ca, Sr, Ba an increasing overall compressibility under hydrostatic pressure is inferred from the respective EOS's, but the elastic constants C ij exhibit highly anisotropic features with large magnitudes of C 33 along the tetragonal c axis versus smaller C 11 = C 22 along a, b. Decreasing C 33 -C 11 along the title compounds signals decreasing anisotropy. The three ternaries are calculated as small gap insulators in agreement with experimental results of conductivity. The chemical bonding characterizes strong Zn-N bonds versus weaker AE–N thus reflecting the crystal anisotropy. 2
Domaines
Matériaux
Origine : Fichiers produits par l'(les) auteur(s)
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