Average single bond strength and optical basicity of Bi 2O 3–B 2O 3 and Sb 2O 3–B 2O 3 glasses

Abstract

Single bond strengths have been proposed of Bi–O bond equal to 102.5 kJ/mol in BiO 6 group and of Sb–O bond equal to 229 kJ/mol in SbO 3 group. Equations for calculation of average single bond strength B M–O of Bi 2O 3–B 2O 3 and Sb 2O 3–B 2O 3 glasses have been suggested taking into account the contribution of different structural units namely BiO 6, SbO 3, BO 3 and BO 4 groups. It has been found that the B M–O of Bi 2O 3–B 2O 3 and Sb 2O 3–B 2O 3 glasses decreases with increasing Bi 2O 3 or Sb 2O 3 content up to 233 kJ/mol at 65 mol% Bi 2O 3 and up to 256 kJ/mol at 90 mol% Sb 2O 3. The observed increase of refractive index based optical basicity Λ(n o) with decreasing B M–O of Bi 2O 3–B 2O 3 and Sb 2O 3–B 2O 3 glasses has been discussed with increase the number of Bi–O–B, Sb–O–B, Bi–O–Bi and Sb–O–Sb chemical bonds containing oxide ions with increased polarizability in the glass structure. It has been discussed that high refractive index glasses with high optical basicity and weak chemical bonds are promising materials for application as components of non-linear optical devices.