S3 State Models of Nature’s Water Oxidizing Complex: Analysis of Bonding and Magnetic Exchange Pathways, Assessment of Experimental Electron Paramagnetic Resonance Data, and Implications for the Water Oxidation Mechanism

2021 ◽  
Vol 125 (36) ◽  
pp. 10097-10107
Author(s):  
Thomas A. Corry ◽  
Patrick J. O’Malley
Keyword(s):  
Water Oxidation ◽  
Complex Analysis ◽  
Oxidation Mechanism ◽  
Magnetic Exchange ◽  
Electron Paramagnetic Resonance Data ◽  
Paramagnetic Resonance ◽  
Resonance Data ◽  
State Models ◽  
Electron Paramagnetic ◽  
Water Oxidizing Complex

Investigation of the Spin Hamiltonian Parameters and the Local Structure of Two Ni3+ Centers in KTaO3

2004 ◽  
Vol 59 (4-5) ◽  
pp. 203-208 ◽  
Author(s):  
Shao-Yi Wu ◽  
Hui-Ning Dong ◽  
Wang-He Wei
Keyword(s):  
Covalent Bonding ◽  
Interstitial Oxygen ◽  
Nearest Neighbour ◽  
Spin Hamiltonian ◽  
Electron Paramagnetic Resonance Data ◽  
Paramagnetic Resonance ◽  
Local Structures ◽  
Resonance Data ◽  
Hamiltonian Parameters ◽  
Electron Paramagnetic

The spin Hamiltonian anisotropic g factors g∥ and g⊥ and the local structures of the Ni3+ centers I and II in KTaO3 are theoretically investigated by using the perturbation formulas of the spin Hamiltonian parameters for 3d7 ions in tetragonally distorted octahedrons and dodecahedrons. By analyzing the electron paramagnetic resonance data of the studied systems, the centers I and II can be attributed to Ni3+ ions occupying octahedral Ta5+ (associated with a nearest-neighbour oxygen vacancy VO along the C4 axis) and the dodecahedral K+ (associated with a nearest-neighbour interstitial oxygen OI along the C4 axis) sites, respectively. Based on these studies, it is found that at the center I the impurity Ni3+ is displaced away from VO by ΔZI ≈ −0.31(2) Å along the C4 axis. At the center II a large off-center displacement, ΔZII ≈ 1.12(2) Å , towards the OI along the C4 axis is obtained, due to Ni3+-OI covalent bonding.

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