Study on carbon contamination and carboxylate group formation in Y2O3-MgO nanocomposites fabricated by spark plasma sintering

IR-transparent MgO-Gd2O3 composite ceramics produced by self-propagating high-temperature synthesis and spark plasma sintering

“…After annealing in air at a temperature of 1000 ℃ , MgO-Gd 2 O 3 composite ceramics become almost white, and the transmission increases significantly. The transmission spectra of MgO-Gd 2 O 3 composite ceramics exhibit an intense absorption band at wavelengths of about 7 μm due to the content of residual carbonate groups and in the range of 2.7-4 μm, associated with residual hydroxyl groups [6,[10][11][12]. Annealing reduces the content of hydroxyl groups but has little effect on the content of residual carbonate groups.…”

“…Since the IR-transmittance of composite ceramics depends significantly on the grain size and the presence of pores, it is necessary to use methods and approaches that ensure the production of a high-density fine-grained ceramic structure. One of the most effective methods for obtaining a fine-grained structure in ceramics is the method of spark plasma sintering (SPS) [3,6,[10][11][12][13][14][15][16]. This method is based on the controlled heating of the powder material in a graphite mold via a sequence of direct current pulses with simultaneous application of uniaxial mechanical pressure.…”

Fabrication of transparent Y2O3 ceramics by two‐step spark plasma sintering

“…The transformed CO 2 gas reacts with metal oxide phase (Y 2 O 3 ), so a carbonate phase is formed and detected in the FT-IR spectra as shown in Figure 6. [19][20][21] The specimen S1500 SPSed at 1500°C with the single-step profile had an IR transmittance that was significantly lower than that of other specimens. All other specimens had a maximum IR transmittance of over 80%, and the highest IR transmittance F I G U R E 6 FT-IR spectra of sintered Y 2 O 3 ceramics after annealing at 1000°C for 30 h. Black is T1500-30, blue is T1500-60, red is T1500-120, and green is S1500 [Color figure can be viewed at wileyonlinelibrary.com] was obtained in T1500-60 (first-step holding time: 60 min).…”

“…As a result, sintered body with decolorized or darken optical appearance are observed. [19][20][21] For removing carbon contamination and oxygen vacancy unintentionally occurred during the SPS process, an additional heat treatment (annealing) was performed at 1000°C for 10 h in an air atmosphere. Through the annealing process, trapped CO gas and precipitated carbon solid phase were transformed to CO 2 gas by reacting with external oxygen, and the optical appearance of the as-sintered body was recovered as shown in Figure 1.…”

Remarkable plasma-resistance performance by nanocrystalline Y2O3·MgO composite ceramics for semiconductor industry applications

“…In our previous report 26 , various transparent ceramics free from light-scattering pores, which also act as the origin and/or as a magnifier of the etching reaction, were proven to exhibit plasma resistance exceeding that of single-crystal sapphire. The nanostructured YM research has been pursued to its excellent mid-wavelength IR transmittance and reliable mechanical properties for use as hypersonic infrared windows, domes and eye-safe laser [27][28][29][30][31] . The plasma resistance of YM composite ceramics has not yet been studied, although the monolithic forms of both Y 2 O 3 and MgO have demonstrated excellent plasma resistance 32 .…”