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Transparent Sm:Y 2 O 3 ceramics were fabricated by spark plasma sintering (SPS). The effects of LiF additive and sintering temperature on the microstructure and optical transmittance of the Sm:Y 2 O 3 ceramics were investigated. The optimal content of LiF additive and sintering temperature was found to be 0.3 wt% and 1500 ℃. The transmittance of Sm:Y 2 O 3 ceramics with a thickness of 1.7 mm reached 75.3% at 609 nm, which is about 94% of the theoretical value. The average grain size of the sample was about 50 µm. [ABSTRACT FROM AUTHOR]

Tb3Al5O12 ( TAG) transparent ceramics were prepared by a reactive sintering method using presintering in a muffle furnace combined with hot isostatic pressing ( HIP) sintering. The dilatometric, differential scanning calorimetry-thermogravimetric ( DSC- TG) curves and optical quality were investigated. The microstructure evolution of the TAG ceramic samples was clarified. Two successive transformations were found to generate a TAG phase, as observed in the dilatometric and DSC- TG curves and XRD patterns of TAG ceramics sintered at different temperature. The changes in average grain size and densification suggest that a 1600°C presintering temperature is suitable for HIP. The optical transmittance of the obtained 0.4 wt% TEOS: TAG transparent ceramics, which were fabricated by a new two-step sintering of presintering at 1600°C in a muffle furnace followed by HIP at 1650°C, can reach above 80% in the visible (vis) and near-infrared ( NIR) regions. Its transmittance was very close to the theoretical limit. To the best of our knowledge, this is the first time that TAG transparent ceramics with ideal optical quality were obtained without vacuum sintering. [ABSTRACT FROM AUTHOR]

Transparent Y 2 O 3 ceramics were fabricated by the solid-state reaction and vacuum sintering method using La 2 O 3 , ZrO 2 and Al 2 O 3 as sintering aids. The microstructure of the Y 2 O 3 ceramics sintered from 1550 °C to 1800 °C for 8 h were analyzed by SEM. The sintering process of the Y 2 O 3 transparent ceramics was optimized. The results showed that when the samples were sintered at 1800 °C for 8 h under vacuum, the average grain sizes of the ceramics were about 3.5 µm. Furthermore, the transmittance of Y 2 O 3 ceramic sintered at 1800 °C for 8 h was 82.1% at the wavelength around the 1100 nm (1 mm thickness), which was close to its theoretical value. Moreover, the refractive index of the Y 2 O 3 transparent ceramic in the temperature range from 30 °C to 400 °C were measured by the spectroscopic ellipsometry method. [ABSTRACT FROM AUTHOR]