Characterization of borate glasses by W-band pulse electron-nuclear double resonance spectroscopy

Journal Article · Tue Oct 21 00:00:00 EDT 2008 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.2991171· OSTI ID:21254775

Kordas, George ^[1]; Goldfarb, Daniella ^[2]

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1. Sol Gel Laboratory for Glass and Ceramics, Institute of Materials Science, NCSR 'Demokritos', 15310 Aghia Paraskevi Attikis (Greece)
2. Department of Chemical Engineering, Weizmann Institute of Science, 76100 Rehovot (Israel)

(100-x) mol % B{sub 2}O{sub 3} x mol %Me{sub 2}O (Me=Li,Na,K) glasses, exposed to {gamma}-{sup 60}Co irradiation to produce paramagnetic states, were characterized by W-band (95 GHz) pulse electron-nuclear double resonance (ENDOR) spectroscopy in order to characterize local structures occurring in the range of compositions between x=16 and x=25 at which the 'boron oxide' anomaly occurs. The high resolution of nuclear frequencies allowed resolving the {sup 7}Li and {sup 11}B ENDOR lines. In the samples with x=16 and x=20 glasses, {sup 11}B hyperfine couplings of 16, 24, and 36 MHz were observed and attributed to the tetraborate, triborate, and boron oxygen hole center (BOHC) structures, respectively. The x=25 samples showed hyperfine couplings of 15 MHz for the tetraborate and 36 MHz for BOHC. Density functional theory (DFT) calculations predicted for these structures negative hyperfine couplings, which were confirmed by W-band ENDOR. This suggests that a spin polarization mechanism accounts for the negative hyperfine structure splitting.

• OSTI ID: 21254775
• Journal Information: Journal of Chemical Physics, Vol. 129, Issue 15; Other Information: DOI: 10.1063/1.2991171; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
36 MATERIALS SCIENCE
BORON OXIDES
COBALT 60
DENSITY FUNCTIONAL METHOD
ENDOR
GAMMA RADIATION
GLASS
HYPERFINE STRUCTURE
LITHIUM COMPOUNDS
MHZ RANGE 01-100
PARAMAGNETISM
POLARIZATION
PULSED IRRADIATION
SODIUM COMPOUNDS
SPECTROSCOPY
SPIN ORIENTATION