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基于电卡效应(ECE)的固态制冷技术具有高能效比、电场直接驱动、易于集成化等优势，在微制冷技术领域应用前景广阔。钛酸钡基(BaTiO3)铁电陶瓷因其较高的极化强度和丰富的相结构成为最具潜力的电卡材料之一，然而，目前其进一步发展受限于低击穿电场、高烧结温度、高电卡性能以及宽工作温区难以同时实现等难点。本工作采用传统固相反应法制备了一种无铅Ba0.97Ca0.03Sn0.1Ti0.9O3–xCuO–yLi_2CO3(BCST,x=0,y=0;BCST–C,x=0.2%(质量分数)，y=0;BCST–L,x=0,y=1.5%;BCST–CL,x=0.2%,y=1.5%)陶瓷材料，研究了烧结助剂CuO/Li_2CO3对BCST陶瓷材料物相结构、微观形貌和电学性能的影响。结果表明，烧结助剂的引入促进了陶瓷晶粒的致密化生长，优化了击穿电场，并且在保持BCST陶瓷材料宽温域连续相变特性的同时提高了其介电常数。最终，样品BCST-CL陶瓷在宽工作温区获得了提升的电卡性能，其中：ΔTmax=3.37 K(55℃，160 kV·cm–1)，该工作为电卡陶瓷材料性能的进一步提升提供了一种可行策略。
Abstract：Introduction Refrigeration technology is widely used in military, commercial, industrial, and civilian fields. However, the existing mechanical compression refrigeration technology faces limitations such as large volume, high energy consumption, low cooling efficiency, and environmental unfriendliness, making it unable to meet the growing demands of emerging technological fields. The electrocaloric effect(ECE), which refers to the alignment of dipoles in polar materials under an electric field, leading to changes in entropy(ΔS) and temperature(ΔT), offers a promising alternative. Solid-state electrocaloric coolers based on the ECE are directly driven by electrical energy, which can achieve heat transfer and cooling. They exhibit some advantages such as high energy efficiency, ease of miniaturization and integration, and environmental friendliness, making them a highly potential and efficient refrigeration technology. Barium titanate(BaTiO3)-based ceramics have attracted extensive research attention in the electrocaloric field due to their excellent polarization strength and rich phase structures. However, some challenges such as low breakdown electric fields, high sintering temperatures, and the inability to simultaneously optimize working temperature ranges and polarization strength hinder their practical applications. To address these issues, this work was to incorporate sintering additives CuO/Li_2CO3 into lead-free Ba0.97Ca0.03Sn0.1Ti0.9O3 ceramics to promote dense grain growth and optimize the breakdown electric field. The dielectric constant was improved, while maintaining the broad temperature range and continuous phase transition characteristics of BCST ceramics, ultimately achieving a large electrocaloric temperature change of 3.37 K(@55 ℃, 160 kV·cm-1). Methods Ba0.97Ca0.03Sn0.1Ti0.9O3 powder was synthesized by a conventional solid-state reaction sintering method at 1200 ℃ with BaCO3, CaCO3, SnO2, and TiO2 as raw materials in a stoichiometric ratio. The ceramic powder was then pressed into disks with the dimensions of φ13 mm×1 mm and sintered at 1350–1500 ℃ for 3 h to obtain dense ceramic samples. After sintering, the ceramic samples were polished, and gold electrodes were sputtered onto their surfaces. The polarization-electric field hysteresis loops(P-E loop) at room temperature were recorded by a model FETS-2000 ferroelectric tester(Wuhan Yanhe Technology Co., Ltd., China) under a frequency of 10 Hz. The values of ΔT were tested through a model Rd F P/N 27134-3 heat flux sensor. The dielectric properties were obtained by a model PK-CPT1705 test system(PolyK Technologies Co., USA) with a testing temperature range from 25 to 150 ℃ and a frequency range from 100 Hz to 100 k Hz. The microstructure of the grain was determined by a model Gemini SEM 300 scanning electron microscope(SEM)(Zeiss Co., Germany) and a model 7000 S/L X-ray diffractometer(XRD)(Shimadzu Corp., Japan). Results and discussion The XRD patterns reveal that all ceramic samples exhibit a pure perovskite structure, indicating that Cu2+ and Li+ ions diffuse into the BCST lattice to form a solid solution. The addition of CuO/Li_2CO3 causes the XRD diffraction peaks shifting to lower angles, indicating that Li+(the radius of 0.73 ?) and Cu2+(0.71 ?) substitute the B-site Ti4+(0.61 ?) and Sn4+(0.71 ?), leading to a lattice expansion. The SEM images demonstrate that the incorporation of CuO/Li_2CO3 results in significant grain growth and well-developed, highly dense microstructures in the ceramic samples. The grain size increases from 7 μm to 46 μm due to the low melting points of CuO/Li_2CO3, which induces liquid-phase sintering effects during the early stages of the sintering process, thus promoting mass transfer and facilitating grain growth and ceramic densification. Dielectric temperature spectra indicate that the addition of CuO/Li_2CO3 significantly enhances the dielectric constant of BCST ceramics. This improvement can be attributed to two factors, i.e., the increase in grain size; second, the aliovalent acceptor doping of Cu2+ and Li+ substituting Ti4+ and Sn4+, which generates lattice defects and oxygen vacancies VO··. These defects coupled to form dipole clusters, thereby enhancing the dielectric constant. Also, the local random electric fields caused by the charge mismatch between Cu2+/Li+ and Ti4+/Sn4+, as well as the average ionic size effect, due to the reduction in the phase transition temperature. Polarization–electric field(P–E) loops show a significant increase in the polarization strength of the ceramic samples with the addition of CuO/Li_2CO3, which can also be attributed to the role of dipole clusters. The electrocaloric performance of the material is greatly enhanced, with the BCST-CL ceramic achieving a giant electrocaloric temperature change of ΔT = 3.37 K(i.e., at 55 ℃, E = 160 kV·cm–1). Conclusions The Ba0.97Ca0.03Sn0.1Ti0.9O3(BCST) ceramic samples with varying amounts of CuO/Li_2CO3 sintering additives exhibited a single perovskite structure, characterized by large, well-developed grains and a dense microstructure. The addition of CuO/Li_2CO3 sintering agents enhanced the dielectric constant of the material, while preserving the broad continuous phase transition temperature range of BCST. During the sintering process, Cu2+ and Li+ ions entered the grains, leading to lattice expansion and increased ferroelectric displacement. Also, as acceptor dopants, they formed defect dipole clusters with oxygen vacancies, thereby improving the material's polarization strength. The direct measurement tests demonstrated a significant enhancement in the electrocaloric temperature change(ΔT) of the ceramic samples, while maintaining excellent operational stability. The BCST-CL composition achieved a maximum ΔT of 3.37 K(at 55 ℃, 160 kV·cm–1), providing a feasible strategy for further improving the performance of electrocaloric ceramic materials.
[1] SHI J Y, HAN D L, LI Z C, et al. Electrocaloric cooling materials and devices for zero-global-warming-potential, high-efficiency refrigeration[J].Joule, 2019, 3(5):1200–1225.
[2] YUMRUTAS R, KUNDUZ M, KANO M. Exergy analysis of vapor compression refrigeration systems[J]. Exergy, An International Journal,2002, 2(4):266–272.
[3] VELDERS G J M, FAHEY D W, DANIEL J S, et al. The large contribution of projected HFC emissions to future climate forcing[J].Proc Natl Acad Sci USA, 2009, 106(27):10949–10954.
[4] ZHAO D L, TAN G. A review of thermoelectric cooling:Materials,modeling and applications[J]. Appl Therm Eng, 2014, 66(1/2):15–24.
[5] RAM N R, PRAKASH M, NARESH U, et al. Review on magnetocaloric effect and materials[J]. J Supercond Nov Magn, 2018,31(7):1971–1979.
[6] TORELLóA, DEFAY E. Electrocaloric coolers:A review[J]. Adv Electron Mater, 2022, 8(6):2101031.
[7] CIRILLO L, GRECO A, MASSELLI C. Cooling through barocaloric effect:A review of the state of the art up to 2022[J]. Therm Sci Eng Prog, 2022, 33:101380.
[8] BRUEDERLIN F, BUMKE L, CHLUBA D C, et al. Elastocaloric cooling on the miniature scale:A review on materials and device engineering[J]. Energy Technol, 2018, 6(8):1588–1604.
[9] VALANT M. Electrocaloric materials for future solid-state refrigeration technologies[J]. Prog Mater Sci, 2012, 57(6):980–1009.
[10] MISCHENKO A S, ZHANG Q, SCOTT J F, et al. Giant electrocaloric effect in thin-film PbZr0.95Ti0.05O3[J]. ChemInform, 2006, 37(23):no.
[11] BAI Y, ZHENG G P, DING K, et al. The giant electrocaloric effect and high effective cooling power near room temperature for Ba TiO3thick film[J]. J Appl Phys, 2011, 110(9):094103.
[12] DAMODARAN A R, AGAR J C, PANDYA S, et al. New modalities of strain-control of ferroelectric thin films[J]. J Phys Condens Matter,2016, 28(26):263001.
[13]张超,岑方杰,肖文荣,等.铁电陶瓷的电卡效应及其应用[J].硅酸盐学报, 2022, 50(3):642–660.ZHANG Chao, CEN Fangjie, XIAO Wenrong, et al. J Chin Ceram Soc,2022, 50(3):642–660.
[14] BAI Y, HAN X, DING K, et al. Combined effects of diffuse phase transition and microstructure on the electrocaloric effect in Ba1-xSrxTi O3 ceramics[J]. Appl Physi Letters, 2013, 103(16):162902.
[15] LUO Z D, ZHANG D W, LIU Y, et al. Enhanced electrocaloric effect in lead-free Ba Ti1–xSnxO3 ceramics near room temperature[J]. Appl Phys Lett, 2014, 105(10):102904.
[16] LI J N, ZHANG D W, QIN S Q, et al. Large room-temperature electrocaloric effect in lead-free Ba HfxTi1-xO3 ceramics under low electric field[J]. Acta Mater, 2016, 115:58–67.
[17] LIU Y, DKHIL B, DEFAY E. Spatially resolved imaging of electrocaloric effect and the resultant heat flux in multilayer capacitors[J]. ACS Energy Lett, 2016, 1(3):521–528.
[18] LI S S, LI X J, ZHANG X L, et al. Influence of protective layer thinning on the electrocaloric performance of 0.8Ba(Ti0.82Zr0.18)O3–0.2Ba(Ti0.9Sn0.1)O3 multilayer ceramic films[J]. J Mater Sci Mater Electron, 2022, 33(33):25436–25445.
[19] HAN F, BAI Y, QIAO L J, et al. A systematic modification of the large electrocaloric effect within a broad temperature range in rare-earth doped Ba TiO3 ceramics[J]. J Mater Chem C, 2016, 4(9):1842–1849.
[20] ZHOU Y Z, LIN Q R, LIU W F, et al. Compositional dependence of electrocaloric effect in lead-free(1-x)Ba(Zr0.2Ti0.8)O3–x(Ba0.7Ca0.3)Ti O3 ceramics[J]. RSC Adv, 2016, 6(17):14084–14089.
[21] WU P, LOU X J, LI J N, et al. Direct and indirect measurement of electrocaloric effect in lead-free(100–x)Ba(Hf0.2Ti0.8)O3–x(Ba0.7Ca0.3)Ti O3 ceramics near multi-phase boundary[J]. J Alloys Compd, 2017,725:275–282.
[22] DU J Z, QIU L, YANG C, et al. Structure and electrical properties in Cu O-modified BCZT lead-free piezoelectric ceramics[J]. J Electroceram,2022, 49(3):125–134.
[23] ZHAO L, ZHANG B P, ZHOU P F, et al. Effect of Li2O addition on sintering and piezoelectric properties of(Ba, Ca)(Ti, Sn)O3 lead-free piezoceramics[J]. J Eur Ceram Soc, 2015, 35(2):533–540.
[24] WANG X J, TIAN F, ZHAO C L, et al. Giant electrocaloric effect in lead-free Ba0.94Ca0.06Ti1–xSnxO3 ceramics with tunable Curie temperature[J]. Appl Phys Lett, 2015, 107(25):252905.
[25] ZHAO L, ZHANG B P, ZHOU P F, et al. Phase structure and property evaluation of(Ba, Ca)(Ti, Sn)O3 sintered with Li2CO3 addition at low temperature[J]. J Am Ceram Soc, 2014, 97(7):2164–2169.
[26] JAIN A, WANG Y G, WANG N, et al. Critical role of CuO doping on energy storage performance and electromechanical properties of Ba0.8Sr0.1Ca0.1Ti0.9Zr0.1O3 ceramics[J]. Ceram Int, 2020, 46(11):18800–18812.
[27] ZHANG B W, LI L X, LUO W J. Oxygen vacancy regulation and its high frequency response mechanism in microwave ceramics[J]. J Mater Chem C, 2018, 6(41):11023–11034.
[28] ZHAO C L, WU H J, LI F, et al. Practical high piezoelectricity in barium titanate ceramics utilizing multiphase convergence with broad structural flexibility[J]. J Am Chem Soc, 2018, 140(45):15252–15260.
[29] ZHAO C L, YANG J L, HUANG Y L, et al. Broad-temperature-span and large electrocaloric effect in lead-free ceramics utilizing successive and metastable phase transitions[J]. J Mater Chem A, 2019, 7(44):25526–25536.
[30] MOULSON A J, HERBERT J M. Materials, properties,applications[M]. Berlin:Springer Dordrecht, 1990.
[31] HU W B, LIU Y, WITHERS R L, et al. Electron-pinned defect-dipoles for high-performance colossal permittivity materials[J]. Nat Mater,2013, 12(9):821–826.
[32] LU B, YAO Y B, JIAN X D, et al. Enhancement of the electrocaloric effect over a wide temperature range in PLZT ceramics by doping with Gd3+and Sn4+ions[J]. J Eur Ceram Soc, 2019, 39(4):1093–1102.
[33] ZHAO C L, HUANG Y L, WU J G. Multifunctional barium titanate ceramics via chemical modification tuning phase structure[J]. InfoMat,2020, 2(6):1163–1190.
[34] HAYNES W M, LIDE D, BRUNO T. CRC handbook of chemistry and physics, 2009–2010, 90th ed[J]. J Am Chem Soc, 2009, 131(35):12862.
[35] SAWANGWAN N, BARREL J, MACKENZIE K, et al. The effect of Zr content on electrical properties of Ba(Ti1–xZrx)O3 ceramics[J]. Appl Phys A, 2008, 90(4):723–727.
[36] BEN L B, SINCLAIR D C. Anomalous Curie temperature behavior of A-site Gd-doped Ba Ti O3 ceramics:The influence of strain[J]. Appl Phys Lett, 2011, 98(9):092907.
[37] LAI L X, LI B, TIAN S, et al. Giant electrostrain in lead-free textured piezoceramics by defect dipole design[J]. Adv Mater, 2023, 35(29):e2300519.
[38] HUANGFU G, WANG J, ZHANG H, et al. Deciphering the Effect of Defect Dipoles on the Polarization and Electrostrain Behavior in Perovskite Ferroelectrics[J]. Nano Letters, 2024, 24(39):12148–12155.
[39] YANG Y, ZHOU L, LI Y H, et al. Interfacial polarization engineering enables superior energy storage performance in(Pb, La)(Zr,Sn,Ti)O3-based antiferroelectric ceramics[J]. Ceram Int, 2024, 50(20):38314–38322.
[40] ZHANG C, DOU Z M, ZENG S Z, et al. Substantially enhanced electrocaloric effect in Ba(Zr0.2Ti0.8)O3 lead-free ferroelectric ceramics via lattice stress engineering[J]. ACS Appl Mater Interfaces, 2023,15(14):18065–18073.
[41] LU S G, LIN X W, LI J, et al. Enhanced electrocaloric strengths at room temperature in(SrxBa1-x)(Sn0.05Ti0.95)O3 lead-free ceramics[J]. J Alloys Compd, 2021, 871:159519.
[42] LU S G, CAI Z H, OUYANG Y X, et al. Electrical field dependence of electrocaloric effect in relaxor ferroelectrics[J]. Ceram Int, 2015, 41:S15–S18.
[43] ZHAO C L, HE T, LIN C, et al. Comparison of electric field-dependent property in Ba TiO3-based piezoceramics between single and coexisting phases[J]. J Am Ceram Soc, 2023, 106(9):5381–5391.
[44] BAI Y, HAN X, QIAO L. Optimized electrocaloric refrigeration capacity in lead-free(1-x)BaZr0.2Ti0.8O3-x Ba0.7Ca0.3Ti O3 ceramics[J].Appl Phys Letters, 2013, 102(25):252904.
[45] WANG J F, YANG T Q, CHEN S C, et al. Nonadiabatic direct measurement electrocaloric effect in lead-free Ba,Ca(Zr, Ti)O3ceramics[J]. J Alloys Compd, 2013, 550:561–563.
[46] DU H L, CHANG Y F, LI C W, et al. Ultrahigh room temperature electrocaloric response in lead-free bulk ceramics via tape casting[J]. J Mater Chem C, 2019, 7(23):6860–6866.
[47] SANLIALP M, SHVARTSMAN V V, ACOSTA M, et al. Strong electrocaloric effect in lead-free 0.65Ba(Zr0.2Ti0.8)O3–0.35(Ba0.7Ca0.3)Ti O3 ceramics obtained by direct measurements[J]. Appl Phys Lett,2015, 106(6):062901.
[48] LI T Y, LIU X Y, SHI S, et al. Large electrocaloric efficiency over a broad temperature span in lead-free BaTiO3-based ceramics near room temperature[J]. Appl Phys Lett, 2017, 111(20):202902.
[49] ZHAO L, KE X Q, ZHOU Z J, et al. Large electrocaloric effect over a wide temperature range in Ba TiO3-modified lead-free ceramics[J]. J Mater Chem C, 2019, 7(5):1353–1358.
[50] JIAN X D, LU B, LI D D, et al. Enhanced electrocaloric effect in Sr2+-modified lead-free Ba ZrxTi1–xO3 ceramics[J]. ACS Appl Mater Interfaces, 2019, 11(22):20167–20173.
基本信息:
DOI：10.14062/j.issn.0454-5648.20250113
中图分类号:TQ174.1
引用信息:
[1]曾十之,肖文荣,张光祖,等.CuO/Li_2CO_3对钛酸钡基铁电陶瓷电卡效应的影响[J].硅酸盐学报,2025,53(12):3684-3693.DOI:10.14062/j.issn.0454-5648.20250113.
基金信息:
国家自然科学基金（52172114,52372108,52272110）; 武汉市自然科学基金探索项目（2024040801020214）; 湖北省自然科学基金（2023AFB647）; 湖北科技人才服务企业计划（2023DJ083）; 中央高校基本科研业务费（NO.TCJJ20242213）; 光谷实验室创新项目（OVL2024BB011,OVL24BB011P）