Effect of Ca²⁺ and Mg²⁺ ions on the sintering and spectroscopic properties of cr‐doped yttrium aluminum garnet ceramics

Abstract

In this work, we investigated the effects of Ca2+ and Mg2+ ions and annealing temperature on the spectroscopic parameters of chromium‐doped yttrium aluminum garnet ceramics (Cr:YAG). Samples were obtained with either a separate or a simultaneous addition of calcium and magnesium oxides. To achieve this, aqueous suspensions were prepared using Y2O3, Al2O3, Cr2O3, MgO, and CaO high‐purity powders as raw materials. The obtained suspensions were freeze‐granulated, pressed into pellets, debinded, and subjected to reactive sintering in vacuum at 1715°C for 6 h. Each material was annealed in air with temperatures between 1300 and 1700°C. Samples were also compared to Cr:YAG ceramics with the addition of silica as a sintering aid. All the materials obtained were then exposed to 445 nm excitation, and emission spectra in the visible and infrared wavelengths were recorded. The results showed that the emission spectra of Cr:YAG ceramics varied according to the annealing conditions: as‐sintered samples exhibited strong emissions of around 680 nm and, after air annealing, of around 1400 nm. This phenomenon is attributed to the Cr3+→Cr4+ transition. Samples doped solely with MgO exhibited the highest emission intensity in the infrared region. Thus, Mg2+ ions provided the best conversion efficiency of chromium ions.

Shortwave Infrared Luminescence of Tetravalent Chromium and Divalent Nickel: Phosphor Design Principles and Applications

“…Then, the grain boundaries relieve the embedded stress in grains with the concurrent solubility enhancement of the divalent cations. This effect is commonly designated as the grain boundary-induced charge compensation effect. , Although charge compensation benefits obtaining Cr 4+ emission, the conversion efficiency is highly limited. The grain boundary is not limited to the above effect; it can also act as a rapid channel for the diffusion of oxygen, which promotes the conversion of Cr 4+ .…”

Preparation of YAG nanopowders and ceramics via coprecipitation: Effects of treatment modes of precipitates

“…Yttrium aluminum garnet (Y 3 Al 5 O 12 , YAG) has been widely known as an important transparent material for window, fluorescent, and solid-state laser application due to its excellent optical properties. [1][2][3][4][5][6][7] Compared with YAG single crystals, polycrystalline YAG ceramics can realize large sizes, desired shapes, multifunctional composite structures, high-concentration and homogeneous ion doping, short production cycles, and low costs under the premise of ensuring satisfactory mechanical, chemical, and optical properties, [8][9][10][11][12] thus, attracting increasing attention. Obtaining a high-quality powder with nanoscale size, good dispersity and narrow size distribution is a key precondition for the preparation of high-performance YAG transparent ceramics.…”