scholarly journals EPR Study of the Mn-Doped Magnesium Titanate Ceramics

2022 ◽  
Author(s):  
Igor P. Vorona ◽  
Valentyna Nosenko ◽  
Sergii M. Okulov ◽  
Dariya Savchenko ◽  
Taras Petrenko ◽  
...  
Keyword(s):  
Optical Studies ◽  
Paramagnetic Resonance ◽  
Magnesium Titanate ◽  
Molar Ratios ◽  
Titanate Ceramics ◽  
Hamiltonian Parameters ◽  
Structural Probes ◽  
Electron Paramagnetic ◽  
Mn Doped ◽  
Titanate Ceramic

Abstract Manganese-doped magnesium titanate ceramic samples obtained by a solid-state reaction via sintering in the air from a mixture of MgO and TiO2 powders of different molar ratios were analyzed by electron paramagnetic resonance (EPR) technique. The EPR signals of Mn2+ ions (S = 5/2, І = 5/2) in crystal phases of MgO, Mg2TiO4, and MgTiO3 were detected. We have obtained the following spin Hamiltonian parameters for Mn2+ ions: g = 2.0015, A ~ 81 ∗ 10-4 cm-1 (in MgO phase); g = 2.0029, A ~ 73.8 ∗ 10-4 cm-1, b2 0 = 35 ∗ 10-4 cm-1 (in Mg2TiO4 phase); g = 2.004, A ~ 79 ∗ 10-4 cm-1, b2 0 = 165 ∗ 10-4 cm-1 (in MgTiO3 phase). Despite the presence of Mn4+ centers in both Mg2TiO4:Mn and MgTiO3:Mn ceramics confirmed by previous optical studies, no EPR signals related to Mn4+ ions (S = 3/2, І = 5/2) were found. The Mn2+ EPR signals are proposed as structural probes in manganese-doped magnesium titanate ceramics.

A Novel Electron Paramagnetic Resonance Phenomenon in a Barium Stronium Titanate Ceramic

2011 ◽  
Vol 295-297 ◽  
pp. 1050-1054 ◽  
Author(s):  
Da Yong Lu ◽  
Xiu Yun Sun
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Resonance Phenomenon ◽  
Tetragonal Symmetry ◽  
Paramagnetic Resonance ◽  
Vacancy Defects ◽  
Average Size ◽  
Increasing Temperature ◽  
Titanate Ceramics ◽  
Electron Paramagnetic ◽  
Titanate Ceramic

The electron paramagnetic resonance (EPR) technique was employed to investigate the point defects in barium strontium titanate ceramics. All samples showed a strong EPR signal with g = 2.000, which was indexed as intrinsic Ti-vacancy defects. In (Ba0.85Sr0.15)TiO3ceramic, which showed a tetragonal symmetry and consisted of the crystallites with average size of ~ 220 nm, a novel EPR powder spectrum was observed - the g-factor of theg= 2.000 signal evolved into ag-tensor, and the two weak signals withg3= ~ 2.6 andg1= ~ 1.6 gradually shifted toward the g2 = 2.000 signal and approached to each other with increasing temperature.

scholarly journals DFT Protocol for EPR Prediction of Paramagnetic Cu(II) Complexes and Application to Protein Binding Sites

2018 ◽  
Vol 4 (4) ◽  
pp. 55 ◽  
Author(s):  
Giuseppe Sciortino ◽  
Giuseppe Lubinu ◽  
Jean-Didier Maréchal ◽  
Eugenio Garribba
Keyword(s):  
Binding Sites ◽  
Density Functional ◽  
Computational Procedure ◽  
Paramagnetic Resonance ◽  
Functional Theory ◽  
Protein Binding Sites ◽  
The Mean ◽  
Hamiltonian Parameters ◽  
Electron Paramagnetic

With the aim to provide a general protocol to interpret electron paramagnetic resonance (EPR) spectra of paramagnetic copper(II) coordination compounds, density functional theory (DFT) calculations of spin Hamiltonian parameters g and A for fourteen Cu(II) complexes with different charges, donor sets, and geometry were carried out using ORCA software. The performance of eleven functionals was tested, and on the basis of the mean absolute percent deviation (MAPD) and standard deviation (SD), the ranking of the functionals for Az is: B3LYP > B3PW91 ~ B3P86 > PBE0 > CAM-B3LYP > TPSSh > BH and HLYP > B2PLYP > MPW1PW91 > ω-B97x-D >> M06; and for gz is: PBE0 > BH and HLYP > B2PLYP > ω-B97x-D > B3PW91~B3LYP~B3P86 > CAM-B3LYP > TPSSh~MPW1PW91 >> M06. With B3LYP the MAPD with respect to A z exp t l is 8.6% with a SD of 4.2%, while with PBE0 the MAPD with respect to g z exp t l is 2.9% with a SD of 1.1%. The results of the validation confirm the fundamental role of the second order spin-orbit contribution to Az. The computational procedure was applied to predict the values of gz and Az of the adducts formed by Cu(II) with albumin and two fragments of prion protein, 106–126 and 180–193.

Electron Paramagnetic Resonance in Ge/Si Heterostructures with Mn-Doped Quantum Dots

JETP Letters ◽  
2019 ◽  
Vol 109 (4) ◽  
pp. 270-275
Author(s):  
A. F. Zinovieva ◽  
V. A. Zinovyev ◽  
N. P. Stepina ◽  
A. V. Katsuba ◽  
A. V. Dvurechenskii ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Electron Paramagnetic Resonance ◽  
Paramagnetic Resonance ◽  
Doped Quantum Dots ◽  
Electron Paramagnetic ◽  
Mn Doped

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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