Microstructural Master Alloys Features of Aluminum–Erbium System

Aluminum master alloys with rare earth metals are widely studied by many scientists around the world, but research on the production of Al-Er master alloys is still limited. The purpose of this work is to study the microstructure parameters of aluminum-erbium master alloys obtained by metallothermic reduction of salt mixtures containing erbium oxide or fluoride. The structural features were investigated by optical and scanning electron microscopy, and the dependence of the microhardness of the eutectic and solid solution fields of obtained master alloys on the content of erbium in the master alloy was determined. Studies have shown that master alloys obtained by metallothermic reduction of erbium compounds from chloride–fluoride melts are characterized by a uniform distribution of Al3Er intermetallic compounds in the volume of double eutectic [(Al) + Al3Er] and have a strong grain refinement effect. The analysis of the microstructure showed that the structure of the master alloys varies depending on the content of erbium. When the content of erbium in the master alloy is up to 6 wt.%, the eutectic structure is preserved. When the content of erbium in the master alloy is 8 wt.% or more, the structure becomes a solid solution with individual inclusions of various shapes and intermetallic compounds.

Thermal, Optical, and IR-Emission Properties of Extremely Low Hydroxyl TeO2-WO3-Bi2O3-La2O3-xEr2O3 Glasses for Mid-Infrared Photonics

A series of glass samples of the tungsten–tellurite system TeO2-WO3-Bi2O3-(4-x) La2O3-xEr2O3, x = 0; 0.4; 0.5; 0.7; 1.2; 2; 4 mol%, CEr = 0 - 15 × 1020 cm−3 were synthesized from high-purity oxides in an oxygen flow inside a specialized sealed reactor. In all samples of the series, an extremely low content of hydroxyl groups was achieved (~n × 1016 cm−3, more than 4 orders of magnitude lower than the concentration of erbium ions), which guarantees minimal effects on the luminescence properties of Er3+. The glasses are resistant to crystallization up to 4 mol% Er2O3, and the glass transition temperatures do not depend on the concentration of erbium oxide when introduced by replacing lanthanum oxide. Thin 0.2 mm plates have high transmittance at a level of 20% in the 4.7–5.3 µm range, and the absorption bands of hydroxyl groups at about 2.3, 3, and 4.4 µm, which are typical for ordinary tellurite glass samples, are indistinguishable. The introduction of erbium oxide led to an insignificant change in the refractive index. Er2O3-concentration dependences of the luminescence intensities and lifetimes near the wavelengths of 1.53 and 2.75 μm were found for the 4I13/2–4I15/2 and 4I11/2–4I13/2 /transitions of the Er3+ ion. The data obtained are necessary for the development of mid-infrared photonics; in particular, for the design of Er3+-doped fiber lasers.