1993/01/01 by Norio Mochida, Sekiya, Takao, Mochida, Norio +7
Materials Science · #Glass properties and applications #Material Dynamics and Properties #Radiation Shielding Materials Analysis
paper · doi:10.34657/13989
<sup>11</sup>B Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) spectra of BO<sub>3/2</sub>-TeO<sub>2</sub> glasses have been used to determine the compositional dependence of the fraction of 4-coordinated boron atoms, N<sub>4</sub> = BO4/(BO<sub>3/2</sub>+BO<sub>4</sub>). In 1 BO<sub>3</sub> ∙ 99 TeO<sub>2</sub> (mol%) glass, almost all boron atoms form BO<sub>4</sub> tetrahedra. The fraction N<sub>4</sub> decreases with increase of BO<sub>3/2</sub> content. The authors propose a glass structural model in which the TeO<sub>3</sub> trigonal pyramids formed by a part of the tellurium atoms are connected with the BO<sub>4</sub> tetrahedra by vertex-sharing. An excess and a deficiency of local charges of a TeO<sub>3</sub> trigonal pyramid and a BO<sub>4</sub> tetrahedron compensate each other. The conversion of a BO<sub>3</sub> triangle to a BO<sub>4</sub> tetrahedron is concurrent with the formation of a TeO<sub>3</sub> trigonal pyramid.