Yb:(YLa)₂O₃laser ceramics produced by microwave sintering

Flash Microwave Sintering of Transparent Yb:(LaY)2O3 Ceramics

“…(a)]. Nothing of this sort was seen in the microstructure of samples of the same composition microwave heated at a much slower rate of 5°C/min, where smooth grain boundaries were only observed. It is worth noting that similar segregation of small spheroid particles at grain boundaries was observed in a study of the microstructure of BaCe 0.8 Gd 0.2 O 3‐δ powder compacts heated conventionally under an applied ac electric voltage .…”

On the Mechanism of Microwave Flash Sintering of Ceramics

“…Isolated droplets, a fraction of a micron in size, located along the grain boundaries are observed in the sample heated at a rate of 50 °C/min to a temperature of 1500 °C (Figure 3a). In previous studies with samples of the same composition, microwave heated at a much slower rate of 5 °C/min [26], no such droplets were seen in the microstructure. With an increase in the microwave heating rate to 100 and 150 °C/min, the particles merge together forming layers, up to 0.3 µm in thickness, which surround the grains (Figure 3b).…”

Effects of divalent dopants on the microstructure and conversion efficiency of Cr4+ ions in Cr,Me:YAG (Me - Ca, Mg, Ca/Mg) transparent ceramics

“…4) indicating a high optical quality of the sintered samples. The formation of Cr 4+ ions in the Cr,Ca:YAG ceramics takes place during annealing in an oxidizing ambient where the tetravalent impurities can be stabilized through the formation of structural defects in the lattice [34][35][36][37]. To recharge chromium into the tetravalent state, the samples were annealed in air at 1450°C for 15 h. The air annealing provides the rise of the absorption bands belonging to Cr 4+ ions that lead to the drop in transparency of the samples (Fig 4 dash line).…”