[2] [2] ROTHMAN A, KALABUKHOV S, SVERDLOV N, et al. The effect of grain size on the mechanical and optical properties of spark plasma sintering-processed magnesium aluminate spinel MgAl2O4［J］. International Journal of Applied Ceramic Technology, 2014, 11(1): 146-153.

[3] [3] LIU X, WANG X Z, ZHU J Q, et al. Thermal-mechanical response of microscale functional film for infrared window［J］. Transactions of Nonferrous Metals Society of China, 2014, 24(6): 1791-1799.

[4] [4] XIE J X, MAO X J, LI X K, et al. Influence of moisture absorption on the synthesis and properties of Y2O3-MgO nanocomposites［J］. Ceramics International, 2017, 43(1): 40-44.

[5] [5] GAO Y T, QIAO J L, NIU J, et al. Research on the performance of thermal shock and stress with infrared optical domes［C］//SPIE Proceedings, 7th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Large Mirrors and Telescopes. Harbin, China. SPIE, 2014: 92800S1-92800S7.

[7] [7] GAN L, PARK Y J, PARK M J, et al. Facile fabrication of highly transparent yttria ceramics with fine microstructures by a hot-pressing method［J］. Journal of the American Ceramic Society, 2015, 98(7): 2002-2004.

[8] [8] MUOTO C K, JORDAN E H, GELL M, et al. Phase homogeneity in Y2O3-MgO nanocomposites synthesized by thermal decomposition of nitrate precursors with ammonium acetate additions［J］. Journal of the American Ceramic Society, 2011, 94(12): 4207-4217.

[9] [9] MUOTO C K, JORDAN E H, GELL M, et al. Effects of precursor chemistry on the structural characteristics of Y2O3-MgO nanocomposites synthesized by a combined sol-gel/thermal decomposition route［J］. Journal of the American Ceramic Society, 2011, 94(2): 372-381.

[10] [10] MUOTO C K, JORDAN E H, GELL M, et al. Phase homogeneity in MgO-ZrO2 nanocomposites synthesized by a combined sol-gel/thermal decomposition route［J］. Journal of the American Ceramic Society, 2010, 93(10): 3102-3109.

[11] [11] HARRIS D C, CAMBREA L R, JOHNSON L F, et al. Properties of an infrared-transparent MgO: Y2O3 nanocomposite［J］. Journal of the American Ceramic Society, 2013, 96(12): 3828-3835.

[13] [13] XU S Q, LI J, LI C Y, et al. Hot pressing of infrared-transparent Y2O3-MgO nanocomposites using sol-gel combustion synthesized powders［J］. Journal of the American Ceramic Society, 2015, 98(3): 1019-1026.

[15] [15] XU S Q, LI J, LI C Y, et al. Infrared-transparent Y2O3-MgO nanocomposites fabricated by the glucose sol-gel combustion and hot-pressing technique［J］. Journal of the American Ceramic Society, 2015, 98(9): 2796-2802.

[16] [16] WU N, LI X D, ZHANG M, et al. Synthesis of nanopowders with low agglomeration by elaborating Φ values for producing Gd2O3-MgO nanocomposites with extremely fine grain sizes and high mid-infrared transparency［J］. Journal of the European Ceramic Society, 2021, 41(4): 2898-2907.

[18] [18] XIE J X, MAO X J, ZHU Q Q, et al. Influence of synthesis conditions on the properties of Y2O3-MgO nanopowders and sintered nanocomposites［J］. Journal of the European Ceramic Society, 2017, 37(13): 4095-4101.

[19] [19] WATANABE T. Grain boundary engineering: historical perspective and future prospects［J］. Journal of Materials Science, 2011, 46(12): 4095-4115.