scholarly journals Electron paramagnetic resonance studies of radiation induced defects in single crystals of lithium sulfate

1967 ◽  
Author(s):  
Clifford L. Aseltine
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Single Crystals ◽  
Lithium Sulfate ◽  
Paramagnetic Resonance ◽  
Radiation Induced ◽  
Induced Defects ◽  
Electron Paramagnetic

Radiation-induced defects in montebrasite: An electron paramagnetic resonance study of O – hole and Ti3+ electron centers

2020 ◽  
Vol 105 (7) ◽  
pp. 1051-1059
Author(s):  
José R. Toledo ◽  
Raphaela de Oliveira ◽  
Lorena N. Dias ◽  
Mário L.C. Chaves ◽  
Joachim Karfunkel ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Electron Irradiation ◽  
Color Centers ◽  
Hydroxyl Groups ◽  
Γ Irradiation ◽  
Paramagnetic Resonance ◽  
Radiation Induced ◽  
Induced Defects ◽  
Electron Paramagnetic ◽  
Hole Centers

Abstract Montebrasite is a lithium aluminum phosphate mineral with the chemical formula LiAlPO4(Fx,OH1–x) and considered a rare gemstone material when exhibiting good crystallinity. In general, montebrasite is colorless, sometimes pale yellow or pale blue. Many minerals that do not have colors contain hydroxyl ions in their crystal structures and can develop color centers after ionization or particle irradiation, examples of which are topaz, quartz, and tourmaline. The color centers in these minerals are often related to O− hole centers, where the color is produced by bound small polarons inducing absorption bands in the near UV to the visible spectral range. In this work, colorless montebrasite specimens from Minas Gerais state, Brazil, were investigated by electron paramagnetic resonance (EPR) for radiation-induced defects and color centers. Although γ irradiation (up to a total dose of 1 MGy) did not visibly modify color, a 10 MeV electron irradiation (80 MGy) induced a pale greenish-blue color. Using EPR, O− hole centers were identified in both γ- or electron-irradiated montebrasite samples showing superhyperfine interactions with two nearly equivalent 27Al nuclei. In addition, two different Ti3+ electron centers were also observed. From the γ irradiation dose dependency and thermal stability experiments, it is concluded that production of O− hole centers is limited by simultaneous creation of Ti3+ electron centers located between two equivalent hydroxyl groups. In contrast, the concentration of O− hole centers can be strongly increased by high-dose electron irradiation independent of the type of Ti3+ electron centers. From detailed analysis of the EPR angular rotation patterns, microscopic models for the O− hole and Ti3+ electron centers are presented, as well as their role in the formation of color centers discussed and compared to other minerals.

scholarly journals X-Band Rapid-Scan Electron Paramagnetic Resonance of Radiation-Induced Defects in Tooth Enamel

2015 ◽  
Vol 184 (2) ◽  
pp. 175 ◽  
Author(s):  
Zhelin Yu ◽  
Alexander Romanyukha ◽  
Sandra S. Eaton ◽  
Gareth R. Eaton
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Tooth Enamel ◽  
Paramagnetic Resonance ◽  
Rapid Scan ◽  
X Band ◽  
Radiation Induced ◽  
Induced Defects ◽  
Electron Paramagnetic

EPR of VO2+ in ZnTiF6 · 6H2O

1996 ◽  
Vol 51 (4) ◽  
pp. 245-248
Author(s):  
Geetha Jayaram ◽  
V. G. Krishnan
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Single Crystals ◽  
Spin Hamiltonian ◽  
Paramagnetic Resonance ◽  
Tutton Salts ◽  
Bonding Parameters ◽  
Superhyperfine Structure ◽  
Vanadyl Ion ◽  
Electron Paramagnetic

Abstract Electron Paramagnetic Resonance (EPR) studies have been carried out on the vanadyl (VO2) ion doped in single crystals of ZnTiF6 • 6H2O. The spectra indicate the presence of one set of eight lines characteristic of only one occupation site. The V-O bond orientation is along one of the three Zn-H2O bond directions in the trigonally distorted [Zn(H2O)6] octahedra. This behaviour is unlike that reported for vanadyl ion substituting for the M(H2O)6 sites in the Tutton salts, alums and AlCl3 • 6H2O. The Spin-Hamiltonian and bonding parameters for the [VO(H2O)5] complex have been evaluated. The hyperfine linewidths are 0.8 mT at 300 K and 77 K. No proton superhyperfine structure was observed at both these temperatures.

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