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Thermo‐Optic Properties and Electronic Polarizability in Alkali Tellurite Glasses
Author(s) -
Honma Tsuyoshi,
Ito Noriko,
Komatsu Takayuki,
Dimitrov Vesselin
Publication year - 2010
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2010.03852.x
Subject(s) - polarizability , alkali metal , refractive index , molar volume , analytical chemistry (journal) , thermal expansion , chemistry , mineralogy , materials science , thermodynamics , physics , molecule , organic chemistry , optoelectronics , metallurgy
The refractive indices ( n ) and densities (ρ) of x Li 2 O–(100− x )TeO 2 glasses with x =15–30 and x Na 2 O–(100− x )TeO 2 glasses with x =10–20 are measured in the temperature range of 30°–150°C in order to clarify thermo‐optic coefficients (d n /d T ) and the temperature dependence of the electronic polarizability of oxide ions () and optical basicity (Λ). It is found that the values of n , , and Λ increase almost linearly with increasing temperature. The values of d n /d T are around 7 × 10 −5 K −1 and tend to decrease with increasing alkali content (Li 2 O, Na 2 O). In contrast, the values of d /d T and dΛ/d T are almost constant, irrespective of the alkali content. It is suggested that electronic polarizability has an important contribution on thermo‐optic coefficients, but the contribution of volume thermal expansion on thermo‐optic coefficients cannot be ignored. In the analyses of electronic polarizabilities of alkali tellurite glasses, the concept of group optical basicity for TeO 3 and TeO 4 structural units is also applied. It is explained that large thermo‐optic coefficients in Li 2 O–TeO 2 and Na 2 O–TeO 2 glasses are composed of oxides having small average single bond strengths and large optical basicities.