Preparation and Thermal Properties of Rare Earth Tantalates (RETaO<sub>4</sub>) High-Entropy Ceramics

Zhu, Jiatong; Lou, Zhihao; Zhang, Ping; Zhao, Jia; Meng, Xuanyu; Gao, Feng

doi:10.15541/jim20200426

Cited by 21 publications

(8 citation statements)

References 25 publications

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“…9(d), (5RE 1/5 )TaO 4 had 57%-69% lower thermal conductivity than 8YSZ at 1200 ℃. In addition, the intrinsic thermal conductivity (2.82-0.87 W•m −1 •K −1 , 100-1200 ℃) of 5HEC-1 is lower than that of the currently reported most high-entropy rare-earth tantalates, e.g., Zhu et al [22] reported the intrinsic thermal conductivity of (Nd 1/4 Sm 1/4 Eu 1/4 Gd 1/4 )TaO 4 , (Nd 1/5 Sm 1/5 5Eu 1/5 Gd 1/5 Dy 1/5 )TaO 4 , and (Nd 1/6 Sm 1/6 Eu 1/6 Gd 1/6 Dy 1/6 Ho 1/6 )TaO 4 corresponding to 2.98-1.24, 2.95-1.29, and 2.78-1.23 W•m -1 •K -1 from 100 to 1000 ℃, respectively. Wang et al [21,23] studied that the intrinsic thermal conductivity of (Y 0.1 Nd 0.1 Sm 0.1 Gd 0.1 Dy 0.1 Ho 0.1 Er 0.1 Tm 0.1 Yb 0.1 Lu 0.1 )TaO 4 and (Y 0.2 Ce 0.2 Sm 0.2 Gd 0.2 Dy 0.2 )TaO 4 corresponds to 2.6-…”

Section: Thermal Propertiesmentioning

confidence: 64%

“…To further depress the thermal conductivity of single-RE RETaO 4 using the high-entropy strategy, Wang et al [21] reported that (5RE 0.2 )TaO 4 has decreased intrinsic thermal conductivity (2.6-1.2 W•m -1 •K -1 ) from 100 to 900 ℃. Zhu et al [22] reported the intrinsic thermal conductivity of (Nd 1/4 Sm 1/4 Eu 1/4 Gd 1/4 )TaO 4 , (Nd 1/5 Sm 1/5 5Eu 1/5 Gd 1/5 Dy 1/5 )TaO 4 , and (Nd 1/6 Sm 1/6 Eu 1/6 Gd 1/6 Dy 1/6 Ho 1/6 )TaO 4 to be 2.98-1.23 W•m -1 •K -1 from 100 to 1000 ℃. Wang et al [23] studied the intrinsic thermal conductivity of (10RE 0.1 )TaO 4 ranging from 2.2 to 1.0 W•m −1 •K −1 (100-1200 ℃).…”

Section: Introduction mentioning

confidence: 99%

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Revealing the low thermal conductivity of high-entropy rare-earth tantalates via multi-scale defect analysis

Wang,

Jin,

Song

et al. 2023

Journal of Advanced Ceramics

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Thermal barrier coating (TBC) materials can improve energy conversion efficiency and reduce fossil fuel use. Herein, novel rare earth tantalates RETaO 4 , as promising candidates for TBCs, were reassembled into multi-component solid solutions with a monoclinic structure to further depress thermal conductivity via an entropy strategy. The formation mechanisms of oxygen vacancy defects, dislocations, and ferroelastic domains associated with the thermal conductivity are demonstrated by aberration-corrected scanning transmission electron microscopy. Compared to single-RE RETaO 4 and 8YSZ, the intrinsic thermal conductivity of (5RE 1/5 )TaO 4 was decreased by 35%-47% and 57%-69% at 1200 ℃, respectively, which is likely attributed to multi-scale phonon scattering from Umklapp phonon-phonon, point defects, domain structures, and dislocations. r ¯3 R + E /r 5 T + a and low-temperature thermal conductivity are negatively correlated, as are the ratio of elastic modulus to thermal conductivity (E/κ) and high-temperature thermal conductivity. Meanwhile, the high defects' concentration and lattice distortion in high-entropy ceramics enhance the scattering of transverse-wave phonons and reduce the transverse-wave sound velocity, leading to a decrease in the thermal conductivity and Young's modulus. In addition, 5HEC-1 has ultra-low thermal conductivity, moderate thermal expansion coefficients, and high hardness among three five-component high-entropy samples. Thus, 5HEC-1 with superior thermal barrier and mechanical properties can be used as promising thermal insulating materials.

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Section: Thermal Propertiesmentioning

confidence: 64%

Section: Introduction mentioning

confidence: 99%

Revealing the low thermal conductivity of high-entropy rare-earth tantalates via multi-scale defect analysis

Wang,

Jin,

Song

et al. 2023

Journal of Advanced Ceramics

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“…Besides, the mechanical properties and plasticity of RETaO 4 (RE = Nd, La, Sm, Gd, Eu, Dy) materials are found to change regularly and become worse and worse with the decrease of atomic radius [9]. In general, yttrium tantalate materials modified by rare earth elements have many advantages, such as great mechanical properties, better thermal stability, and a larger thermal expansion coefficient [10]. Therefore, understanding the doping effects of rare earth elements and Nb on YTaO 4 and its phase stability and mechanical properties are significant.…”

Section: Introductionmentioning

confidence: 99%

Phase Stability and Mechanical Properties of the Monoclinic, Monoclinic-Prime and Tetragonal REMO4 (M = Ta, Nb) from First-Principles Calculations

Xiao

Yang

et al. 2022

Coatings

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YTaO4 and the relevant modification are considered to be a promising new thermal barrier coating. In this article, phase stability and mechanical properties of the monoclinic (M), monoclinic-prime (M′), and tetragonal (T) REMO4 (M = Ta, Nb) are systematically investigated from first-principles calculations method based on density functional theory (DFT). Our calculations show that M′-RETaO4 is the thermodynamically stable phase at low temperatures, but the stable phase is a monoclinic structure for RENbO4. Moreover, the calculated relative energies between M (or M′) and T phases are inversely proportional to the ionic radius of rare earth elements. It means that the phase transformation temperature of M′→T or M→T could decrease along with the increasing ionic radius of RE3+, which is consistent with the experimental results. Besides, our calculations exhibit that adding Nb into the M′-RETaO4 phase could induce phase transformation temperature of M′→M. Elastic coefficient is attained by means of the strain-energy method. According to the Voigt–Reuss–Hill approximation method, bulk modulus, shear modulus, Young’s modulus, and Poisson’s ratio of T, M, and M’ phases are obtained. The B/G criterion proposed by Pugh theory exhibits that T, M, and M’ phases are all ductile. The hardness of REMO4 (M = Ta, Nb) phases are predicted based on semi-empirical equations, which is consistent with the experimental data. Finally, the anisotropic mechanical properties of the REMO4 materials have been analyzed. The emerging understanding provides theoretical guidance for the related materials development.

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“…Inspired by this concept, highentropy materials have been broadened to more categories: high-entropy ceramics (HECs), including oxides [13], carbides [14,15], borides [16], silicides [17], and sulfides [18]. The HECs have been found to exhibit better structure stability, enhanced mechanical properties, colossal dielectric constant, amorphous-like thermal conductivity, superionic conductivity, and chemical catalysis properties [19][20][21][22][23][24]. High-entropy oxide (HEO) (Mg,Ni,Co,Cu,Zn)O has been designed while the entropy stabilization mechanism was first proved in 2015 by Rost et al [13].…”

Section: Introduction mentioning

confidence: 99%

Ti4+-incorporated fluorite-structured high-entropy oxide (Ce,Hf,Y,Pr,Gd)O2−δ: Optimizing preparation and CMAS corrosion behavior

Cheng

Zhang²,

Liu³

et al. 2022

J Adv Ceram

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Environmental barrier coatings (EBCs) with excellent chemical resistance and good high-temperature stability are of great significance for their applications in next-generation turbine engines. In this work, a new type of high-entropy fluorite-structured oxide (Ce0.2Hf0.2Y0.2Pr0.2Gd0.2)O2−δ (HEFO-1) with different Ti4+ contents were successfully synthesized. Minor addition of Ti4+ could be dissolved into a high-entropy lattice to maintain the structure stable, effectively reducing the phase formation temperature and promoting the shrinkage of bulk samples. Heat treatment experiments showed that all the samples remained a single phase after annealing at 1200–1600 °C for 6 h. In addition, high-entropy (Ce0.2Hf0.2Y0.2Pr0.2Gd0.2Ti0.2x)O2−δ demonstrated great resistance to calcium—magnesium—alumina—silicate (CMAS) thermochemical corrosion. When the content of Ti was increased to x = 0.5, the average thickness of the reaction layer was about 10.5 after being corroded at 1300 °C for 10 h. This study reveals that high-entropy (Ce0.2Hf0.2Y0.2Pr0.2Gd0.2Ti0.2x)O2−δ is expected to be a candidate for the next-generation EBC materials with graceful resistance to CMAS corrosion.

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Preparation and Thermal Properties of Rare Earth Tantalates (RETaO₄) High-Entropy Ceramics

Cited by 21 publications

References 25 publications

Revealing the low thermal conductivity of high-entropy rare-earth tantalates via multi-scale defect analysis

Revealing the low thermal conductivity of high-entropy rare-earth tantalates via multi-scale defect analysis

Phase Stability and Mechanical Properties of the Monoclinic, Monoclinic-Prime and Tetragonal REMO4 (M = Ta, Nb) from First-Principles Calculations

Ti4+-incorporated fluorite-structured high-entropy oxide (Ce,Hf,Y,Pr,Gd)O2−δ: Optimizing preparation and CMAS corrosion behavior

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Preparation and Thermal Properties of Rare Earth Tantalates (RETaO4) High-Entropy Ceramics

Cited by 21 publications

References 25 publications

Revealing the low thermal conductivity of high-entropy rare-earth tantalates via multi-scale defect analysis

Revealing the low thermal conductivity of high-entropy rare-earth tantalates via multi-scale defect analysis

Phase Stability and Mechanical Properties of the Monoclinic, Monoclinic-Prime and Tetragonal REMO4 (M = Ta, Nb) from First-Principles Calculations

Ti4+-incorporated fluorite-structured high-entropy oxide (Ce,Hf,Y,Pr,Gd)O2−δ: Optimizing preparation and CMAS corrosion behavior

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Preparation and Thermal Properties of Rare Earth Tantalates (RETaO₄) High-Entropy Ceramics