Features of electronic polarizability and approach to unique properties in tellurite glasses

Abstract

Tellurite glasses showing unique properties such as low phonon energy and high linear and nonlinear optical properties have been considered as promising materials for photonic device applications. The present article reviews the current status of the electronic polarizability in binary and ternary tellurite glasses and approaches their unique properties. Tellurite glasses consisting of basic modifier oxides (eg, Na2O, ZnO) and basic conditional glass forming oxide (TeO2) exhibit the features of high electronic polarizability and weak chemical bond strength, that is, refractive index‐based large oxide ion polarizability αO2‐(no), large optical basicity ∧(no), small interionic interaction parameter A(no), and small single bond strength BM‐O. The values of αO2‐(no), ∧(no), and A(no) in several tellurite glasses containing WO3, Nb2O5, and Bi2O3 were estimated in this article, and a good correlation was confirmed between ∧(no) and A(no). Unique properties of low glass transition temperature, fragile structural relaxation behavior, poor mechanical properties, high third‐order nonlinear optical susceptibilities in tellurite glasses were discussed from the point of electronic polarizability.

Electronic polarizability in silicate glasses by comparison of experimental and theoretical optical basicities

“…In the so‐called bond energy criterion proposed by Sun, 37 the glass‐forming acidic oxide SiO 2 has a large single bond strength B M–O of a chemical bond Si–O, B M–O = 443.5 kJ/mol, and contrary, the modifier basic oxides have small single bond strengths, e.g., B M–O = 84 kJ/mol for Na 2 O. Dimitrov and Komatsu 15,38,39 proposed an approach for the calculation of the average single bond strength of glasses based on the Sun's data, indicating that the average single bond strength of silicate glasses decreases with increasing modifier's content. They also reported that silicate glasses have large chemical bond strengths compared with GeO 2 ‐based and TeO 2 ‐based glasses, e.g., B M–O = 372 kJ/mol for 20Na 2 O–80SiO 2 glass, B M–O = 291 kJ/mol for 20Na 2 O–80GeO 2 glass, and B M–O = 245 kJ/mol for 20Na 2 O–80TeO 2 glass 4 …”

“…Equation () combining α O2− ( n o ) with Λ( n o ) is a proposal by Duffy 3 and indicates the average oxide ion polarizability of a given glass. The estimation of α O2− ( n o ) and Λ( n o ) has been applied to various oxide glasses 4,5,8,9,15 . Compared with the probe ion method, the refractive index‐based optical basicity determined from the Lorentz–Lorenz formula method would be regarded as the average (whole, not local) electronic polarizability of a given glass.…”

“…A good correlation between M(n o ) and the third-order nonlinear optical susceptibility χ (3) has been found in various simple oxides by Dimitrov and Sakka 34 and various oxide glasses by Dimitrov and Komatsu. 8 Equation ( 7) also means that the value of the optical basicity of oxide glasses can be determined from the values of density and energy gap in the combinations of Equations (3)(4)(5), which is called the energy gap-based optical basicity Λ(E g ). 11 For example, the value of Λ(E g ) = 0.52 has been reported for SiO 2 crystal (quartz), which is larger than the value of Λ(n o ) = 0.48.…”

“…After the pioneering work on the electronic polarizability of glasses, i.e., the concept of optical basicity, by Duffy and Ingram, 1–3 optical basicity has been recognized as an extremely important issue in the science and technology of glasses, especially for a deep understanding of glasses and for the development of new innovative glasses. Very recently, the features of electronic polarizability and the correlation between optical basicity and unique properties in the binary and ternary TeO 2 – and Bi 2 O 3 – based glasses with various different compositions have been analyzed and clarified more deeply 4,5 . The optical basicity Λ of an oxide medium is a numerical expression of the average electron donor power of the oxide species constituting the medium, and it is used as a measure of the acid‐base properties of oxides, glasses, slags, molten salts, and so on 1 …”

Stress‐induced crystal axis spiral rotation in multiferroic β'‐Gd2(MoO4)3 observed only in glass crystallization

“…Another idea for the effective relaxation of stresses at the interface between β‐GMO crystals and surrounding super‐cooled liquids is proposed by Kotaka et al, 48 in which B 2 O 3 oxide in Gd 2 O 3 ‐MoO 3 ‐B 2 O 3 glasses is replaced partly with TeO 2 oxide. It is known that B 2 O 3 is the strong glass‐forming oxide, that is, a strong chemical bond strength of B‐O bonds, and TeO 2 belongs to the category of the fragile glass‐forming oxide, that is, a weak chemical bond strength of Te‐O bonds 61 . Generally, B 2 O 3 ‐based glasses consist of tetrahedral BO 4 and trigonal BO 3 units, and TeO 2 ‐based glasses include trigonal bi‐pyramidal TeO 4 and trigonal pyramidal TeO 3 units.…”