Effect of raw material processing on the optical properties of yttrium oxide ceramics

??????? ???????? ?? ?????? ?????? ????? ??????? ????????????? ?? ?????????????????? ????????. ??????? ????? ?????????? ? ???????? ????????????, ???????? ? ????????? ???????????? Y2O3 ???????? ????????? ?????? ????????? ???????????? [1]. ? ??????? ????????? ????? ???????? ??????? ??????? ??????? ????????? ??????. ????????? ???????? (???) ???????? ??????? ? ????????? ??????????? ?????????. ? ??'???? ? ???, ????? ???????? ?????????? ? ??????????? ?????? ?????? ?? ??????? ???????? ??????? ???? ? ??????? ????????? ???????? [2]. ????? ?????? ? ??????????? ?????? ???????? ???????? ? ???? ?? ??????? ?? ??????? ??????????? ???????? Y2O3. ? ????? ?????? ???? ?????????? ?????????? ???????? ??????????? ???????? ?????? ????? (Nippon, Stanford, Solvay ? US RN) ????? ?????? ??? ?????? ??????. ? ?????? ???????, ?? ?????? ????????, ???? ?????? 3 ???.% ZrO2. ??????, ????????????? ?????????? ? ???????? ???????????? ???????????, ??????? ?? ??????? ??? ??????????? 1600 °? ???????? 4 ???. ?? ? ??????? ??? 1735°? ???????? 32 ???. ?? ??????? ????? ?????????? ?????????? ???????? ????? ??????????????????? ?????? (80 ??./??. ???????? 22 ???.). ????? ????????????? ???????? Stanford ???????????????? ????????? ??????? ? ???????? ???????????, ??? ?? ?????????? ??? ??????????. ?????????? ????? ???????? ????? ?????????, ?????????? ????? ?? ???????? ? ?????? ?'???. ????? ???? ???????, ????????? ????????? ?? ???????, ???? Nippon-???????? ???????????????? ??????? ????????? ? ?????????? ??????????????? ? ??????????? ????????? ???????? ??????? ??????????? ????? ??????? ???????? (???) ?? ??????? ????????. ?????? ???????? ????? ???????? ???????? Solvay ? US RN ?????????? ?? ????? ??????????????? ? ??????? ????????????? ??????? ??????????? ??????????. ????? ?????, Nippon Y2O3 ???? ?????? ??? ????????? ??????????. ????????? ????? ???? ?????? (????????? ? ???) ?? ????????? ??????? ? ??????????? ????????-???????? ???????? Y2O3. ??????????? ?????????? ????? ????????? ???????? ? ??????? ?????????? ?? ???????? (300 ??./??., 65 ??.). ?? ????? ???? ?????? ????? ???????? ???????? 21.3 ?2/?, ? ???????? ?????? ???????? ??????? 480 ??. ???????? ????????? ?????? ?? 200 ? 100 ??./??. ?????????? ?? ?????????? ??????? ????????, ? ?????????? ???? ?????? ?? 10 ??? ??????????????? ???????????? ???????? ????? ?????? ???????? ??????? ????? ????????. ???????? Y2O3, ???????? ? ????? ??????? ??????? ?????????? ???????? ??? 1735 °? ???????? 32 ???, ???????????????? ??????? ????????? ????????? 100±0,5% ? ???????? ???????? ???????????? ????? ???? ??????????????? ??????? (78,1 % ??? 1100 ??, ?? ??????? 95,6 % ??? ???????????? ????????). ??????????? ???????? ?? ????????? CNR-ISSMC (?????? CNR-ISTEC), ??????, ?????? ? JECS Trust (???????? No. 2021293) ??????????: [1]J. Kong, D.Y. Tang, J. Lu, et al, Appl. Phys. 79, 449-455 (2004). [2]S. Hríbalova, W. Pabst, J. Eur. Ceram. Soc. 41, 2169-2192 (2021)

Optical ceramics based on yttrium oxide are actively researched as a multifunctional material. Y2O3 ceramics have wide practical applications due to its mechanical and optical properties, chemical and thermal stability [1]. In the process of obtaining such ceramics, it is important to achieve a high sample density. The presence of defects (pores) deteriorates the optical and mechanical properties of the material. In this regard, the choice of raw materials and the study of the influence of their processing methods play a significant role in the creation of the ceramics process [2]. The aim of work is the study of the influence of the initial powders and their processing conditions on the optical properties of Y2O3 ceramics. In this work, the morphology of four commercial yttrium oxide powders (Nippon, Stanford, Solvay, and US RN) was investigated after milling under different conditions. 3 mol.% ZrO2 was chosen as a sintering add. The samples, compacted by uniaxial and cold isostatic pressing, were sintered in air at 1600 °C for 4 h and in vacuum at 1735°C for 32 h. At the first stage, the morphology of the powders after milling at 80 rpm for 22 h was investigated. Among the studied powders, Stanford was characterized by the presence of large and hard agglomerates that do not break down when pressed. The morphology of other powders is more homogeneous, agglomerates are smaller in size and quite soft. Among the samples obtained by air-sintering, only Nippon-ceramic is characterized by high density and uniform microstructure with a minimum number of defects. High values of the surface area of Solvay and US RN powders lead to the appearance of inhomogeneities during uniaxial pressing. Therefore, Nippon Y2O3 was selected for further research. The effect of milling conditions (rate and time) on powder parameters and properties of vacuum-sintered Y2O3 ceramics was determined. The optimal conditions for obtaining powders with high sinterability (300 rpm, 65 min) have been established. Under these conditions, the specific surface area is 21.3 m2/g, and the average particle size is about 480 nm. Decreasing of milling rate to 200 and 100 rpm leads to an increase in the size of the particles, and an increase in the milling time up to 10 h is accompanied by reagglomeration of the particles due to high values of the specific surface area. Y2O3 ceramics, obtained from this powder by vacuum sintering at 1735 °C for 32 years, is characterized by a high relative density of 100±0.5% and the highest optical transmittance among all analysed samples (78.1% at 1100 nm, which is 95.6 % of the theoretical value). Research supported by CNR-ISSMC (formerly CNR-ISTEC), Faenza, Italy and JECS Trust (Contract No. 2021293) References: [1]J. Kong, D.Y. Tang, J. Lu, et al, Appl. Phys. 79, 449-455 (2004). [2]S. Hríbalova, W. Pabst, J. Eur. Ceram. Soc. 41, 2169-2192 (2021)