Porous high-entropy rare-earth phosphate (REPO₄, RE = La, Sm, Eu, Ce, Pr and Gd) ceramics with excellent thermal insulation performance via pore structure tailoring

Abstract

Thermal insulation materials play an increasingly important role in protecting mechanical parts functioning at high temperatures. In this study, a new porous high-entropy (La_1/6Ce_1/6Pr_1/6Sm_1/6Eu_1/6Gd_1/6)PO₄ (HE (6RE_1/6)PO₄) ceramics was prepared by combining the high-entropy method with the pore-forming agent method and the effect of different starch contents (0–60vol%) on this ceramic properties was systematically investigated. The results show that the porous HE (6RE_1/6)PO₄ ceramics with 60vol% starch exhibit the lowest thermal conductivity of 0.061 W·m⁻¹·K⁻¹ at room temperature and good pore structure stability with a linear shrinkage of approximately 1.67%. Moreover, the effect of large regular spherical pores (>10 µm) on its thermal insulation performance was discussed, and an optimal thermal conductivity prediction model was screened. The superior properties of the prepared porous HE (6RE_1/6)PO₄ ceramics allow them to be promising insulation materials in the future.

Keywords

porous high-entropy (La_1/6Ce_1/6Pr_1/6Sm_1/6Eu_1/6Gd_1/6)PO₄ ceramics / high-entropy strategy / pore-forming agent method / thermal insulation material / thermal conductivity

References

[[1]] J. Yang, X. Qian, W. Pan, et al., Diffused lattice vibration and ultralow thermal conductivity in the binary Ln–Nb–O oxide system, Adv. Mater., 31(2019), No. 24, art. No. 1808222.

[[2]] Yang RW, Liang YP, Xu J, et al.. Rare-earth-niobate high-entropy ceramic foams with enhanced thermal insulation performance. J. Mater. Sci. Technol., 2022, 116: 94,

[[3]] Miao C, Liang LX, Zhang F, et al.. Review of the fabrication and application of porous materials from silicon-rich industrial solid waste. Int. J. Miner. Metall. Mater., 2022, 29(3): 424,

[[4]] Nait-Ali B, Haberko K, Vesteghem H, Absi J, Smith DS. Thermal conductivity of highly porous zirconia. J. Eur. Ceram. Soc., 2006, 26(16): 3567,

[[5]] Han Y, Li CW, Bian C, Li SB, Wang CG. Porous anorthite ceramics with ultra-low thermal conductivity. J. Eur. Ceram. Soc., 2013, 33(13–14): 2573,

[[6]] Li DY, Li MS. Porous Y₂SiO₅ ceramic with low thermal conductivity. J. Mater. Sci. Technol., 2012, 28(9): 799,

[[7]] Tian ZL, Zheng LY, Wang JM, Wan P, Li JL, Wang JY. Theoretical and experimental determination of the major thermo-mechanical properties of RE₂SiO₅ (RE = Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y) for environmental and thermal barrier coating applications. J. Eur. Ceram. Soc., 2016, 36(1): 189,

[[8]] Sun YN, Xiang HM, Dai FZ, et al.. Preparation and properties of CMAS resistant bixbyite structured high-entropy oxides RE₂O₃ (RE = Sm, Eu, Er, Lu, Y, and Yb): Promising environmental barrier coating materials for Al₂O_3f/Al₂O₃ composites. J. Adv. Ceram., 2021, 10(3): 596,

[[9]] Du AB, Wan CL, Qu ZX, Pan W. Thermal conductivity of monazite-type REPO₄ (RE = La, Ce, Nd, Sm, Eu, Gd). J. Am. Ceram. Soc., 2009, 92(11): 2687,

[[10]] Feng J, Xiao B, Zhou R, Pan W. Anisotropy in elasticity and thermal conductivity of monazite-type REPO₄ (RE = La, Ce, Nd, Sm, Eu and Gd) from first-principles calculations. Acta Mater., 2013, 61(19): 7364,

[[11]] Zhao ZF, Chen H, Xiang HM, et al.. (La_0.2Ce_0.2Nd_0.2 Sm_0.2Eu_0.2)PO₄: A high-entropy rare-earth phosphate monazite ceramic with low thermal conductivity and good compatibility with Al₂O₃. J. Mater. Sci. Technol., 2019, 35(12): 2892,

[[12]] Zhang PX, Wang EH, Guo CY, Yang T, Hou XM. High-entropy rare earth phosphates (REPO₄, RE = Ho, Tm, Yb, Lu, Dy, Er and Y) with excellent comprehensive properties. J. Eur. Ceram. Soc., 2024, 44(3): 1873,

[[13]] S. Akrami, P. Edalati, M. Fuji, and K. Edalati, High-entropy ceramics: Review of principles, production and applications, Mater. Sci. Eng. R: Rep., 146(2021), art. No. 100644.

[[14]] P. Sarker, T. Harrington, C. Toher, et al., High-entropy high-hardness metal carbides discovered by entropy descriptors, Nat. Commun., 9(2018), art. No. 4980.

[[15]] Zhang PX, Duan XJ, Xie XC, et al.. Xenotime-type high-entropy (Dy_1/7Ho_1/7Er_1/7Tm_1/7Yb_1/7Lu_1/7Y_1/7)PO₄: A promising thermal/environmental barrier coating material for SiQ/SiC ceramic matrix composites. J. Adv. Ceram., 2023, 12(5): 1033,

[[16]] Shao ZJ, Wu Z, Sun LC, et al.. High entropy ultra-high temperature ceramic thermal insulator (Zr_1/5Hf_1/5Nb_1/5Ta_1/5Ti_1/5)C with controlled microstructure and outstanding properties. J. Mater. Sci. Technol., 2022, 119: 190,

[[17]] Liu DB, Zhou ZL, Wang YG, Xu BS. Highly porous (La_1/5Nd_1/5Sm_1/5Gd_1/5Yb_1/5)₂Zr₂O₇ ceramics with ultra-low thermal conductivity. Ceram. Int., 2022, 48(18): 26400,

[[18]] D.B. Liu, X.L. Jia, B.L. Shi, Y.G. Wang, and B.S. Xu, (Sm_0.2Eu_0.2Tb_0.2Dy_0.2Lu_0.2)₂Si₂O₇: A novel high-entropy rare earth disilicate porous ceramics with high porosity and low thermal conductivity, Mater. Chem. Phys., 286(2022), art. No. 126181.

[[19]] T.X. Li, S.D. Wang, W.X. Fan, et al., CALPHAD-aided design for superior thermal stability and mechanical behavior in a TiZrHfNb refractory high-entropy alloy, Acta Mater., 246(2023), art. No. 118728.

[[20]] T.X. Li, W.N. Jiao, J.W. Miao, et al., A novel ZrNbMoTaW refractory high-entropy alloy with in situ forming heterogeneous structure, Mater. Sci. Eng. A, 827(2021), art. No. 142061.

[[21]] P.X. Zhang, E.H. Wang, X.J. Duan, et al., Preparation and characterization of a novel monazite-type high-entropy (La_1/7Ce_1/7Pr_1/7Nd_1/7Sm_1/7Eu_1/7Gd_1/7)PO₄ for thermal/environmental barrier coatings, J. Alloys Compd., 952(2023), art. No. 169978.

[[22]] Huo WL, Zhang XY, Chen YG, et al.. Highly porous zirconia ceramic foams with low thermal conductivity from particle-stabilized foams. J. Am. Ceram. Soc., 2016, 99(11): 3512,

[[23]] Meng XY, Xu J, Yang RW, et al.. Lanthanum zirconate porous ceramics with controllable secondary pores for high-temperature thermal insulation. Ceram. Int., 2022, 48(22): 33976,

[[24]] Meng XY, Xu J, Zhu JT, et al.. Enhancing the thermal insulating properties of lanthanum zirconate porous ceramics via pore structure tailoring. J. Eur. Ceram. Soc., 2021, 41(12): 6010,

[[25]] Yan W, Li N, Han BQ. Preparation and characterization of porous ceramics prepared by kaolinite gangue and Al(OH)₃ with double addition of MgCO₃ and CaCO₃. Int. J. Miner. Metall. Mater., 2011, 18(4): 450,

[[26]] Zhu JB, Yan H. Microstructure and properties of mullite-based porous ceramics produced from coal fly ash with added Al₂O₃. Int. J. Miner. Metall. Mater., 2017, 24(3): 309,

[[27]] Li X, Tao MY, Pan MB, et al.. The preparation and properties of high-strength porous mullite ceramics by a novel non-toxic gelcasting process. J. Eur. Ceram. Soc., 2022, 42(13): 6015,

[[28]] Zhang Y, Wu YJ, Yang XK, et al.. High-strength thermal insulating mullite nanofibrous porous ceramics. J. Eur. Ceram. Soc., 2020, 40(5): 2090,

[[29]] Honda S, Hashimoto S, Yase S, Daiko Y, Iwamoto Y. Fabrication and thermal conductivity of highly porous alumina body from platelets with yeast fungi as a pore forming agent. Ceram. Int., 2016, 42(12): 13882,

[[30]] Hossain SKS, Pyare R, Roy PK. Synthesis of in situ mullite foam using waste rice husk ash derived sol by slip-casting route. Ceram. Int., 2020, 46(8): 10871,

[[31]] Liu JJ, Ren B, Lu YJ, et al.. Novel design of elongated mullite reinforced highly porous alumina ceramics using carbonized rice husk as pore-forming agent. Ceram. Int., 2019, 45(11): 13964,

[[32]] Xu GG, Li J, Cui HZ, He QK, Zhang ZH, Zhan XY. Biotemplated fabrication of porous alumina ceramics with controllable pore size using bioactive yeast as pore-forming agent. Ceram. Int., 2015, 41(5): 7042,

[[33]] Živcová Z, Gregorová E, Pabst W. Porous alumina ceramics produced with lycopodium spores as pore-forming agents. J. Mater. Sci., 2007, 42(20): 8760,

[[34]] Zhao ZF, Xiang HM, Dai FZ, Peng ZJ, Zhou YC. On the potential of porous ZrP₂O₇ ceramics for thermal insulating and wave-transmitting applications at high temperatures. J. Eur. Ceram. Soc., 2020, 40(3): 789,

[[35]] Fukushima M, Yoshizawa YI. Fabrication and morphology control of highly porous mullite thermal insulators prepared by gelation freezing route. J. Eur. Ceram. Soc., 2016, 36(12): 2947,

[[36]] Voigt C, Zienert T, Schubert P, Aneziris CG, Hubálková J. Reticulated porous foam ceramics with different surface chemistries. J. Am. Ceram. Soc., 2014, 97(7): 2046,

[[37]] X.Y. Meng, J. Xu, J.T. Zhu, et al., Pyrochlore-fluorite dual-phase high-entropy ceramic foams with extremely low thermal conductivity from particle-stabilized suspension, Scripta Mater., 194(2021), art. No. 113714.

[[38]] Mohanta K, Kumar A, Parkash O, Kumar D. Low cost porous alumina with tailored microstructure and thermal conductivity prepared using rice husk and sucrose. J. Am. Ceram. Soc., 2014, 97(6): 1708,

[[39]] Novais RM, Seabra MP, Labrincha JA. Ceramic tiles with controlled porosity and low thermal conductivity by using pore-forming agents. Ceram. Int., 2014, 40(8): 11637,

[[40]] Liu JJ, Li YB, Li YW, Sang SB, Li SJ. Effects of pore structure on thermal conductivity and strength of alumina porous ceramics using carbon black as pore-forming agent. Ceram. Int., 2016, 42(7): 8221,

[[41]] Chen H, Xiang HM, Dai FZ, et al.. High porosity and low thermal conductivity high entropy (Zr_0.2Hf_0.2Ti_0.2Nb_0.2Ta_0.2)C. J. Mater. Sci. Technol., 2019, 35(8): 1700,

[[42]] Meng XY, Xu J, Zhu JT, et al.. Porous yttria-stabilized zirconia ceramics with low thermal conductivity via a novel foam-gelcasting method. J. Mater. Sci, 2020, 55(31): 15106,

[[43]] Gong LL, Wang YH, Cheng XD, Zhang RF, Zhang HP. Thermal conductivity of highly porous mullite materials. Int. J. Heat Mass Transf., 2013, 67: 253,

[[44]] Hou ZG, Liu JC, Du HY, Xu H, Guo AR, Wang M. Preparation of porous Y₂SiO₅ ceramics with relatively high compressive strength and ultra-low thermal conductivity by a TBA-based gel-casting method. Ceram. Int., 2013, 39(2): 969,

[[45]] Zhang RB, Fang DN, Chen XM, Pei YM, Wang ZD, Wang YS. Microstructure and properties of highly porous Y₂SiO₅ ceramics produced by a new water-based freeze casting. Mater. Des., 2013, 46: 746,

[[46]] Wu Z, Sun LC, Pan JJ, Wang JY. Fiber reinforced highly porous γ-Y₂Si₂O₇ ceramic fabricated by foam-gelcasting-freeze drying method. Scripta Mater., 2018, 146: 331,

[[47]] Wu Z, Sun LC, Wan P, Li JN, Hu ZJ, Wang JY. In situ foam-gelcasting fabrication and properties of highly porous γ-Y₂Si₂O₇ ceramic with multiple pore structures. Scripta Mater., 2015, 103: 6,

[[48]] Meng XY, Xu J, Zhu JT, et al.. Hierarchically porous lanthanum zirconate foams with low thermal conductivity from particle-stabilized foams. J. Am. Ceram. Soc., 2020, 103(11): 6088,

[[49]] Zhou WY, Zhang Z, Li N, Yan W, Ye GT. A new mullite foamed ceramic prepared by direct-foaming methods in parallel with a mechanical activation technique. Ceram. Int., 2022, 48(14): 20721,

[[50]] Gong LL, Wang YH, Cheng XD, Zhang RF, Zhang HP. A novel effective medium theory for modelling the thermal conductivity of porous materials. Int. J. Heat Mass Transf., 2014, 68: 295,