Fabrication, optical transmittance, and hardness of IR-transparent ceramics made from nanophase yttria

Fabrication of transparent ceramics by millimeter‐wave sintering

“…A reduction of microwave power at temperatures over 700 °C is due to an increase in ionic conductivity of oxide powders and, as a consequence, an increase in their microwave absorption. A sharp drop-down of the microwave power at about 1000 °C is caused by the exothermic reactions of the intermediate Y 4 Al 2 O 9 and YAlO 3 phases with Al 2 O 3 . The increase in the temperature of the sample due to the heat of the exothermic reactions was prevented by immediate automatic decrease in the microwave power.…”

“…However, whereas MWTA is based on the fact that physical or chemical alterations in a material under processing cause variations in its dielectric properties, the method considered in this work is directly connected with the thermal effect at such alterations. The capability of detecting the thermal effect of solid state reactions is of great importance for the process of YAG synthesis from a mixture of oxides because it allows one to obtain in situ information on the characteristic temperatures and completeness of the formation of the intermediate Y 4 Al 2 O 9 and YAlO 3 phases. As noted above, the volumetric heating makes appealing the process of the mm-wave sintering from the standpoint of energy saving.…”

“…To this date, the most widely used method is high vacuum sintering in furnaces with Mo-W heating elements at a pressure of 1×10 -3 Pa and temperature in the range of 1600-1800 °С [2]. More technically sophisticated methods such as hot pressing (HP) [3] and hot isostatic pressing (HIP) [4] are used for sintering, as well as a combined method in which HIP follows the high vacuum sintering [5,6].…”

Fabrication of submicron-grained IR-transparent Y2O3 ceramics from commercial nano-raw powders

“…In addition, mechanical strength is a very important performance parameter in bulk ceramic materials, especially for optical windows or domes when used under extreme conditions, such as at high pressures or elevated temperatures. However, Y 2 O 3 exhibits much poorer mechanical properties in nature compared to other transparent materials, as mentioned above [9]. Therefore, it is crucial to strengthen Y 2 O 3 ceramics before use.…”

Synthesis and Physicochemical Properties of Yttrium Oxide Doped with Neodymium and Lanthanum

“…These features make it a good candidate for application as a material for sight glasses operating at high temperatures and in aggressive environments. 1,2 An important property of this material is its transparency, which may be as high as 70% for visible light and approximately 60% for infrared light. 3 This high transparency, low cutoff energy of phonons, and the ease with which rare earth elements can be incorporated into the Y 2 O 3 lattice, make transparent yttrium oxide an excellent material for manufacturing neodymium Nd:YAG lasers, in which the appropriate quantum transitions are mediated by neodymium ions.…”