Paramagnetic defects in neutron-irradiated α-quartz: Novel Al-associated E’ centers

Abstract

Two new paramagnetic defects (E 14 and E 16 ) have been revealed in neutron-irradiated natural α-quartz by using electron paramagnetic resonance (EPR) spectroscopy. The EPR spectra of the E 16 center as well as a previously reported but incompletely characterized E 11 center demonstrate that their super-hyperfine structures arise from interaction with 27 Al, the first-ever examples of Al-associated E centers in crystalline quartz. The matrices g and A( 29 Si), A( 27 Al) of E 11,16 , g and A( 29 Si) of the E 14 center, have been determined.

Mineralogy and mineral chemistry of quartz: A review

“…4; Li and Pan, 2012; Mashkovtsev et al , 2013). Other well-characterised E ′ centres in quartz include the E ′ 4 and E ′ 11,16 centres (Table S2; Perlson and Weil, 2008; Mashkovtsev and Pan, 2012a, 2016, 2018; Mashkovtsev et al ., 2019). The former contains a proton near the oxygen vacancy, wheras the latter with diagnostic 27 Al superhyperfine structures provide experimental proof for the hypothesis that Al impurity plays an important role in the formation of E ′ centres (Jani et al , 1983; Mashkovtsev and Pan, 2018; Mashkovtsev et al , 2019).…”

“…Other well-characterised E ′ centres in quartz include the E ′ 4 and E ′ 11,16 centres (Table S2; Perlson and Weil, 2008; Mashkovtsev and Pan, 2012a, 2016, 2018; Mashkovtsev et al ., 2019). The former contains a proton near the oxygen vacancy, wheras the latter with diagnostic 27 Al superhyperfine structures provide experimental proof for the hypothesis that Al impurity plays an important role in the formation of E ′ centres (Jani et al , 1983; Mashkovtsev and Pan, 2018; Mashkovtsev et al , 2019). In addition, various E ′′ centres arising from interactions between two neighbouring E ′ centres have been discovered and characterised with the triplet-state model in recent years (Table S2; Mashkovtsev et al , 2007; Mashkovtsev and Pan, 2011, 2012a, 2012b, 2014).…”

EPR study of the E’ defects in optical glasses and cristobalite

“…Note that in α-SiO 2 two new E 11,12 centers with orthorhombic g matrices analogous to those of the E α have been observed [26]. But for the E 11 center the orthorhombic symmetry could be explained by the small HF interaction with a substitutional Al atom involved in the defect [27].…”