Multifrequency ESR analysis of theE{sub {delta}}{sup '} defect in a-SiO{sub 2}

Journal Article · Tue Mar 01 00:00:00 EST 2011 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.83.094118· OSTI ID:21538203

Jivanescu, M; Stesmans, A; Afanas'ev, V V ^[1]

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1. Semiconductor Physics Laboratory, Department of Physics and Institute for Nanoscale Physics and Chemistry (INPAC), University of Leuven, Celestijnenlaan 200 D, B-3001 Leuven (Belgium)

A multifrequency (X, K, Q band) electron spin resonance (ESR) study has been carried out on the nature of the E{sub {delta}}{sup '} defect in vitreous (v) SiO{sub 2}, both at cryogenic and room temperature (T), using two detection modes on six types of commercial v-silica subjected to three kinds of irradiation [UV, vacuum ultraviolet (VUV), and {sup 60}Co {gamma} photons]. The E{sub {delta}}{sup '} signal could be generated only in three types of v-SiO{sub 2}, and only, yet always, by two types of irradiation, VUV and {sup 60}Co {gamma} rays--not UV--suggesting that the E{sub {delta}}{sup '} activation starts predominantly from preexisting sites through ionization processes. The inferred intensity ratio of the resolved {sup 29}Si hyperfine (hf) structure to the central Zeeman signal is found to reassuringly coincide over the observational frequencies and T's studied. The as-inferred average value ({approx_equal}20.3%) alone would point to hf interaction of the unpaired spin with n=4 equivalent Si sites, confirming the center's delocalized nature as initially proposed. Yet, with the inclusion of previous experimental experience, the n=5 case cannot be excluded, and in fact, should be given full consideration as well. In line with the previous conclusion, the result decisively refutes the recurrent theoretically propagated positively charged Si dimer (Si{sub 2}) model, thus urging discontinuation of the use of the Si{sub 2} label for the E{sub {delta}}{sup '} center. In fact, none of the thus-far advanced atomic models may apply, as all are theoretically projected to essentially correspond to n=1(2) cases due to limited spin delocalization. Extrinsic Al-related defects ([AlO{sub 4}]{sup 0}, Al E{sup '}) are co-observed, where a noteworthy finding is that the E{sub {delta}}{sup '} is only observed in those (3) v-silica also showing the Al E{sup '} center, possibly Na{sup +} compensated, in the initial {gamma}-irradiated state. This may signify some indirect role of charge compensators in activating/stabilizing E{sub {delta}}{sup '} centers, which may need incorporation to further theoretical modeling. The exposed T independence of the ESR parameters, including hf, refers to an electronically rigid structure with no dynamical readjustment process occurring in the range T{>=}4.2 K. The experimental absence of the theoretical Si{sub 2} defect is discussed within the context of its projected closely isospectral ESR appearance to the E{sub {delta}}{sup '} signal.

• OSTI ID: 21538203
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 83, Issue 9; Other Information: DOI: 10.1103/PhysRevB.83.094118; (c) 2011 American Institute of Physics; ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM COMPLEXES
ATOMIC MODELS
COBALT 60
CRYSTAL DEFECTS
DIMERS
ELECTRON SPIN RESONANCE
FAR ULTRAVIOLET RADIATION
GAMMA RADIATION
INCLUSIONS
INTERACTIONS
IONIZATION
IRRADIATION
PHYSICAL RADIATION EFFECTS
SILICON 29
SILICON OXIDES
SIMULATION
SODIUM IONS
SPIN
TEMPERATURE RANGE 0273-0400 K
ZEEMAN EFFECT
ANGULAR MOMENTUM
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHALCOGENIDES
CHARGED PARTICLES
COBALT ISOTOPES
COMPLEXES
CRYSTAL STRUCTURE
ELECTROMAGNETIC RADIATION
EVEN-ODD NUCLEI
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IONIZING RADIATIONS
IONS
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MATHEMATICAL MODELS
MINUTES LIVING RADIOISOTOPES
NUCLEI
ODD-ODD NUCLEI
OXIDES
OXYGEN COMPOUNDS
PARTICLE PROPERTIES
RADIATION EFFECTS
RADIATIONS
RADIOISOTOPES
RESONANCE
SILICON COMPOUNDS
SILICON ISOTOPES
STABLE ISOTOPES
TEMPERATURE RANGE
ULTRAVIOLET RADIATION
YEARS LIVING RADIOISOTOPES