A theoretical interpretation is given for the site selectivities of Mn 2+, Fe 2+, Co 2+, Ni 2+, Zn 2+, Cd 2+, and Hg 2+ ions in fully dehydrated zeolite A. This zeolite was first envisioned as being either completely ionic or completely covalent in character. This cation-lattice interaction energies
Site preference of transition-metal elements in B2 NiAl: A comprehensive study
β Scribed by Chao Jiang
- Publisher
- Elsevier Science
- Year
- 2007
- Tongue
- English
- Weight
- 614 KB
- Volume
- 55
- Category
- Article
- ISSN
- 1359-6454
No coin nor oath required. For personal study only.
β¦ Synopsis
First-principles supercell calculations based on density functional theory were performed to study the T = 0 K site preference of 3d (Ti-Cu), 4d (Zr-Ag) and 5d (Hf-Au) transition-metal elements in B2 NiAl. By adopting a statistical-mechanical Wagner-Schottky model within the canonical ensemble, the effects of finite temperature on site preference were further considered. The calculations showed that, at all alloy compositions and temperatures, Co, Tc, Ru, Rh, Re, Os, Ir and Pt have a consistent preference for the Ni sublattice, while Ti, Zr, Nb, Hf and Ta have a consistent preference for the Al sublattice. In contrast, the site preference of V, Cr, Mn, Fe, Cu, Mo, Pd, Ag, W and Au was found to depend on both composition and temperature. The present calculated results compare favorably with existing theoretical and experimental studies in the literature.
π SIMILAR VOLUMES
CrO 2 +TiO 2 (TC), MoO 2 +TiO 2 (TMo), and WO 2 +TiO 2 (TW), prepared by heating in vacuo at 1173+1273 K mixtures of MO 2 (M β«Ψβ¬ Cr, Mo, or W) and TiO 2 , were characterized by XRD and EPR. The transition metal ions were incorporated as isolated and clustered Cr III , Mo IV , and W IV and a small fr
Microwave-absorption techniques have been used for investigating the superconducting behaviour of the recently discovered quaternary rare-earth transition metal borocarhide superconductors. The direct microwave absorption shows a steep drop at 23 K in YPdsB3Co.35. Besides the expected drop in microw