Optical absorption and structure of impurity Ni$^{2+}$ center in tungstate-tellurite glass

TL;DR

This study investigates the optical absorption properties and local structure of Ni$^{2+}$ ions in tungstate-tellurite glass, revealing their environment and impact as impurities through spectral analysis and computer modeling.

Contribution

The paper provides the first detailed spectral and structural analysis of Ni$^{2+}$ in tungstate-tellurite glass, including modeling of its local environment and spectral behavior.

Findings

Ni$^{2+}$ ions are in a trigonal-distorted octahedral environment.

Ni$^{2+}$ exhibits strong absorption, making it a significant impurity.

Good agreement between experimental spectra and Tanabe-Sugano model.

Abstract

Absorption spectra of Ni$^{2+}$ ions in 22WO$_3$--78TeO$_2$ tungstate-tellurite glass were studied and Ni$^{2+}$ extinction coefficient spectral dependence was derived in the 450 -- 2700 nm wavelength range. Computer modeling of the glass structure proved Ni$^{2+}$ ions to be in trigonal-distorted octahedral environment in the tungstate-tellurite glass. Tanabe-Sugano diagram for such an environment was calculated and good description of the observed spectrum of Ni$^{2+}$ ion was obtained. Basing on both absorption spectral range width and the extinction coefficient, nickel should be considered among the most strongly absorbing impurities in the tellurite glasses.