User:Benjah-bmm27/degree/3/NLA
Chemistry of solids, NLA
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Bonding and electronic structure in solids
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- Non-stoichiometry
- The monoxides MO have the rocksalt structure
- TiOx (0.7 > x > 1.25) and VO are metallic conductors
- overlap of t2g 3d orbitals from neighbouring Ti(II) atoms results in a t2g conduction band
- MnO and NiO are insulators because their t2g 3d orbitals are too contracted to overlap due to the greater electronegativity of Mn and Ni
- FeO and CoO are also insulators, whereas second and third row transition metal oxides are more commonly metallic conductors
- Electrical conductivity in transition metal dioxides
- Electrical conductivity in transition metal trioxides
- ReO3 — Re(VI) is d1, lustrous red metallic conductor
- High oxidation state Re so direct d-d orbital overlap very unlikely — partially filled π-band arises from Re(5d)-O(2p) overlap
- WO3 — W(VI) is d0, insulator
- NaxWO3 — W(V) is d1, gold-coloured metallic conductor
Defects and non-stoichiometry
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