Physical, Thermal, and Optical Properties of Mn 2+ and Nd 3+ Containing Barium Phosphate Glasses.

This work reports on various properties and analysis of optical interactions in phosphate glasses containing red-emitting Mn 2+ and near-infrared (NIR)-emitting Nd 3+ ions, which are of interest for energy applications and solar spectral converters. The glasses were made by melting with 50P 2 O 5 -(48 - x )BaO-2MnO- x Nd 2 O 3 ( x = 0, 0.5, 1.0, and 2.0 mol %) nominal compositions and characterized by X-ray diffraction, density and related physical properties, differential scanning calorimetry, dilatometry, UV-vis-NIR optical absorption, and photoluminescence spectroscopy with decay kinetics analysis. The glasses were X-ray amorphous, wherein the physical and thermal properties of the Mn 2+ /Nd 3+ -codoped glasses were largely impacted by Nd 2 O 3 contents. The optical absorption spectra supported the occurrence of Mn 2+ ions and the lack of Mn 3+ in the codoped glasses, while the absorption due to Nd 3+ ions increased steadily with Nd 2 O 3 contents. Analyzing the glass absorption edges via Tauc and Urbach plots was further pursued for a comparison. The photoluminescence evaluation showed a consistent suppression of the emission from Mn 2+ ions with increasing Nd 3+ concentration, while the decay kinetics revealed shorter lifetimes in connection with increased Mn 2+ → Nd 3+ transfer efficiencies. Excitation of Mn 2+ at 410 nm, however, led to the Nd 3+ NIR emission being most intense for 1.0 mol % Nd 2 O 3 , despite the 4 F 3/2 emission decay analysis showing lifetime shortening throughout. Considering the compromise between red and NIR emissions, the Mn-containing glass doped with 0.5 mol % Nd 2 O 3 is put in perspective with the concept of solar spectral conversion.