On 17.03.2025, a seminar was organized by Dr. Kiryl Yasakau in the Department of Materials and Ceramic Engineering (DEMaC).
Prof. dr hab. Yaroslav Zhydachevskyy
Head of the Group of High-Pressure Spectroscopy ON4.1
Institute of Physics of the Polish Academy of Sciences
Al. Lotników 32/46, 02-668 Warsaw, POLAND
Title: Possibilities of tuning of Mn4+ and Cr3+ luminesce in Ga2O3 by alloying with Al2O3 and In2O3
Abstract: The work focuses on the possibilities of tuning the luminescence properties of Mn4+ and Cr3+ ions in gallium oxide (Ga2O3) by alloying with Al2O3 and In2O3.
To address this we carried out a comprehensive study on (Al1-xGax)2O3:Mn4+ (x = 0; 0.05; 0.10; 0.15; 0.2; 0.25; 0.5; 0.75; 1.0), (Ga1‑xAlx)2O3:Cr3+ (y = 0; 0.1; 0.2) and (Ga1‑xInx)2O3:Cr3+ (x = 0.05; 0.1; 0.15; 0.2; 0.3; 0.4; 0.5) phosphors [1, 2]. Our investigation delved into various aspects, including photoluminescence (PL), PL excitation (PLE), diffuse reflection (DR) spectra and PL decay kinetics of the materials over a broad temperature range from 4 to 350 K. Additionally, we studied persistent luminescence (PersL) and thermally stimulated luminescence (TSL) after UV excitation within the temperature range from 77 to 600 K for the Cr3+-doped materials. The phase composition and crystal structure of the materials were examined using the X-ray powder diffraction technique.
Our findings reveal the potential for fine-tuning the performance of the studied materials as NIR persistent phosphors and non-contact luminescence thermometers through the alterations of the chemical composition of the Ga2O3-based host material. Performed low-temperature and time-resolved PL studies shed light on the nature of the Cr3+ and Mn4+ centers present in the alloys. The luminescence results are discussed in correlation with the crystal structure data for the studied materials providing deeper insight into behavior of these materials.
References:
[1] Ya. Zhydachevskyy, V. Mykhaylyk, V. Stasiv, et al., Chemical Tuning, Pressure and Temperature Behavior of Mn4+ Photoluminescence in Ga2O3-Al2O3 Alloys, Inorg. Chem. 61 (2022) 18135-18146.
[2] V. Stasiv, Ya. Zhydachevskyy, V. Stadnik, et al., Chemical tuning of photo- and persistent luminescence of Cr3+-activated b‑Ga2O3 by alloying with Al2O3 and In2O3, J. Alloys Compd. 982 (2024) 173827.
Dr. Mykhailo Chaika
Department of Optical Spectroscopy
Institute of Low Temperature and Structural Research
Okólna 2, 50-422, Wroclaw, Poland.
Title: Advancements and challenges in sintering of Cr4+:YAG transparent ceramics.
Abstract: This work focuses on the influence of the single additives and their combinations on the sintering trajectory of Cr4+:YAG ceramics.
Since the first successfully synthesized transparent Nd:YAG ceramics (Ikesue et al. 1995), the progress in transparent ceramic technology has significantly expanded the scope of applications for both continuous wave (CW) and pulsed lasers. The most popular host for solid state lasers is Nd:YAG which occupies more than half of the laser crystals market. A large fraction of the laser market is occupied by passive Q-switched lasers which can operate in so called “giant pulse” generation mode. The crucial component of these lasers is phototropic material. Cr4+:YAG remains the best choice for Q-switched lasers and suppresses all other alternatives (the exception of LiF crystals which are expensive and short lived). Global Cr4+:YAG Crystals Market Size, Scope And Forecast Report highlight that the Cr4+:YAG Crystals Market has witnessed swift and substantial growth in recent years, with projections indicating a continued significant expansion from 2023 to 2031.
Despite the importance of Cr4+:YAG ceramics, there is a limited number of published research articles. The reason for this is challenges which arise in Cr4+:YAG transparent technology. One of the key components of YAG transparent ceramics technology is usage of TEOS sintering additive. Sintering of transparent YAG ceramics without TEOS sintering additives is one of the most perspective directions for further development of transparent ceramics. So far there are only a few papers that reported the sintering of Nd:YAG transparent ceramics without using TEOS sintering additives. Sintering of high quality Cr4+:YAG transparent ceramics requires absence of TEOS sintering additives which is a challenge by itself. Moreover, Cr4+:YAG require presence of Ca2+ or/and Mg2+ charge compensation further complicates this task. The work focuses on the influence of the single additives and their combinations on the sintering trajectory of Cr4+:YAG ceramics [1].
References:
[1] Chaika, M. (2024). Advancements and challenges in sintering of Cr4+:YAG: A review. Journal of the European Ceramic Society, 44 (13), 7432-7450
