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It is a critical issue to reduce the thermal conductivity and increase the thermal expansion coefficient of ceramic thermal barrier coating (TBC) materials in the course of their utilization. To synthesize samples with different composition and measure their thermal conductivity by the traditional experimental approaches is time-consuming and expensive. Most classic and empirical models work inefficiently and inaccurately when researchers attempt to predict the thermophysical properties of TBC materials. In this research project, we tentatively exploit a Genetic Algorithm-Support Vector Regression (GA-SVR) machine learning model to study the thermophysical properties, illustrated with the potential TBC materials ZrO2 doped DyTaO4, which has resulted in the lowest thermal conductivity in rare earth tantalates RETaO4 system. Meanwhile, we employ statistical parameters of correlation coefficient (R2) and mean square error (MSE) to evaluate the accuracy and reliability of the model. The results reveal that this model has brought about high correlation coefficients of thermal conductivity and thermal expansion coefficient (99.8% and 99.9%, respectively), while the MSE values are 0.00052 and 0.00019, respectively. The doping concentration of ZrO2 was optimized to reach as low as 0.085–0.095, so as to reduce their thermal conductivity further and increase their thermal expansion. This model provides an accurate and reliable option for researchers to design ceramic thermal barrier coating materials.

Rare-earth tantalates and niobates (RE 3 TaO 7 and RE 3 NbO 7 ) have been considered as promising candidate thermal barrier coating (TBC) materials in next generation gas-turbine engines due to their ultra-low thermal conductivity and better thermal stability than yttria-stabilized zirconia (YSZ). However, the low Vickers hardness and toughness are the main shortcomings of RE 3 TaO 7 and RE 3 NbO 7 that limit their applications as TBC materials. To increase the hardness, high entropy (Y 1/3 Yb 1/3 Er 1/3 ) 3 TaO 7 , (Y 1/3 Yb 1/3 Er 1/3 ) 3 NbO 7 , and (Sm 1/6 Eu 1/6 Y 1/6 Yb 1/6 Lu 1/6 Er 1/6 ) 3 (Nb 1/2 Ta 1/2 )O 7 are designed and synthesized in this study. These high entropy ceramics exhibit high Vickers hardness (10.9–12.0 GPa), close thermal expansion coefficients to that of single-principal-component RE 3 TaO 7 and RE 3 NbO 7 (7.9×10 −6 -10.8×10 −6 C −1 at room temperature), good phase stability, and good chemical compatibility with thermally grown Al 2 O 3 , which make them promising for applications as candidate TBC materials.

Rare-earth tantalates (RETaO4) are considered as a type of emerging thermal barrier coating materials applied to the hot components of gas turbines and aerospace engines due to their excellent thermal stability, high-temperature fracture toughness, corrosion resistance and extremely low thermal conductivity. However, the relatively low hardness and thermal expansion coefficients may limit their service lifetime in a harsh engine environment. To address the current limitation of rare-earth tantalates and further optimize the mechanical and thermal properties, the defective fluorite-structured Y₂Zr₂O₇ (YZ) was introduced as a second phase into the YTaO4 (YT) matrix to form YT1−x–YZx (x = 0, 0.25, 0.5, 0.75, 1) composite ceramics in this work. The mechanical and thermal properties of YT1−x–YZx composite ceramics are significantly improved compared to pure-phase YTaO4 ceramics. The Vickers hardness of YT1−x–YZx (x = 0.25, 0.5, 0.75) composite ceramics is 9.1~11.3 GPa, which are 2~2.5 times higher than that of YTaO4 (4.5 GPa). Among them, YT0.75–YZ0.25 exhibits a maximum fracture toughness (3.7 ± 0.5 MPa·m1/2), achieving a 23% improvement compared to YTaO4 (3.0 ± 0.23 MPa·m1/2) and a 118% improvement compared to Y2Zr2O7 (1.73 ± 0.28 MPa·m1/2). The enhancement is attributed to the combined effect of the intrinsic strengthening of the second phase, as well as the residual stress and grain refinement caused by the introduction of a second phase. Additionally, the thermal expansion coefficients of YT1−x–YZx composite ceramics at 1673 K range from 10.3 × 10⁻⁶ K⁻1 to 11.0 × 10⁻⁶ K⁻1, which is also higher than that of YTaO4 (10.0 × 10−6 K−1). Consequently, the superior mechanical and thermal properties indicate that YT–YZ composite ceramics possess promising application prospects for thermal barrier coatings.

Rare earth tantalates (RETaO4), known for their exceptional thermomechanical properties, are promising candidates for next‐generation thermal barrier coatings (TBCs). However, the role of rare earth (RE) species in the CMAS (calcium‐magnesium‐aluminosilicate) corrosion behavior and mechanisms of RETaO4 remains unclear, hindering their design and application as TBCs. This study employs a high‐throughput approach to systematically investigate the CMAS corrosion mechanisms of RETaO4 (RE = Nd, Sm, Eu, Gd, Dy, Ho, Y, and Er) at 1300 °C. Precise analysis of the microstructure and composition reveal that the primary corrosion products are (Ca2‐xREx)(Ta2‐y‐zMgyAlz)O7 solid solutions, along with minor amounts of Ca2RE8(SiO4)6O2 apatite. These corrosion products are observed both in the recession layer and at grain boundaries. The CMAS infiltration depth of RETaO4 increases with the RE ionic radius. First‐principles calculations indicate that the formation enthalpy of corrosion products becomes more exothermic as the RE ionic radius increases, promoting the formation of corrosion products. Additionally, the wetting behavior of liquid CMAS on RETaO4 at high temperatures supports that RETaO4 with smaller RE ionic radius present better corrosion resistance. These findings provide insights into the influence of RE species on the CMAS corrosion behavior of RETaO4, offering guidelines for the rapid screening of CMAS‐resistant TBC materials. This work employs a high‐throughput approach to investigate the CMAS corrosion behavior of RETaO4 at 1300 °C. Corrosion products are found in both the recession layer and at grain boundaries. The CMAS infiltration depth shows a positive correlation with the RE ionic radius, attributed to their influence on the formation enthalpy of the corrosion products.

Rare-earth tantalates, with high density and monoclinic structure, and niobates with monoclinic structure have been paid great attention as potential optical materials. In the last decade, we focused on the crystal growth technology of rare-earth tantalates and niobates and studied their luminescence and physical properties. A series of rare-earth tantalates and niobates crystals have been grown by the Czochralski method successfully. In this work, we summarize the research results on the crystal growth, scintillation, and laser properties of them, including the absorption and emission spectra, spectral parameters, energy levels structure, and so on. Most of the tantalates and niobates exhibit excellent luminescent properties, rich physical properties, and good chemical stability, indicating that they are potential outstanding scintillators and laser materials.

HfO 2 alloying effect has been applied to optimize thermal insulation performance of HoTaO 4 ceramics. X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy are employed to decide the crystal structure. Scanning electronic microscopy is utilized to detect the influence of HfO 2 alloying effect on microstructure. Current paper indicates that the same numbers of Ta 5+ and Ho 3+ ions of HoTaO 4 are substituted by Hf 4+ cations, and it is defined as alloying effect. No crystal structural transition is introduced by HfO 2 alloying effect, and circular pores are produced in HoTaO 4 . HfO 2 alloying effect is efficient in decreasing thermal conductivity of HoTaO 4 and it is contributed to the differences of ionic radius and atomic weight between Hf 4+ ions and host cations (Ta 5+ and Ho 3+ ). The least experimental thermal conductivity is 0.8 W·K −1 ·m −1 at 900 °C, which is detected in 6 and 9 mol%-HfO 2 HoTaO 4 ceramics. The results imply that HfO 2 –HoTaO 4 ceramics are promising thermal barrier coatings (TBCs) due to their extraordinary thermal insulation performance.

Environmental barrier coatings (EBCs) are widely used to protect ceramic matrix composites (CMCs, SiCf/SiC, and Al2O3f/Al2O3), and they should have low thermal expansion coefficients (TECs) matching the CMCs and excellent mechanical properties to prolong their lifetime. Current EBC materials have disadvantages of phase transitions and insufficient mechanical properties, which affect their working temperatures and lifetime. It is necessary to develop new oxide EBCs. Ytterbium tantalate (YbTaO4) is a stable and novel EBC material, and we have improved the mechanical properties and TECs of Yb1−xAlxTaO4 (x = 0.05, 0.1, 0.2, 0.3, 0.4, 0.5) ceramics by replacing Yb with Al. XRD, SEM, and EDS are used to verify the crystal and microstructures, and nano-indentation is used to measure the modulus and hardness when changes in TECs are measured within a thermal expansion device. The results show that the phase structure of Yb1−xAlxTaO4 (x = 0.05, 0.1, 0.2, 0.3, 0.4, 0.5) is stable at 25–1400 °C within air atmosphere, and their high-temperature TECs (6.4–8.9 × 10−6 K−1, 1400 °C) are effectively regulated by introductions of different contents of Al, which enlarge their engineering applications for SiCf/SiC and Al2O3f/Al2O3 CMCs. The evolutions of TECs are analyzed from structural characteristics and phase compositions, and the increased TECs make Yb1−xAlxTaO4 potential EBCs for Al2O3 matrixes. Due to the high bonding strength of Al–O bonds, hardness, as well as Young’s modulus, are enhanced with the increasing Al content, with Yb1−xAlxTaO4 (x = 0.05, 0.1, 0.2, 0.3, 0.4, 0.5) having a nano-hardness of 3.7–12.8 GPa and a Young’s modulus of 100.9–236.6 GPa. The TECs of YbTaO4 are successfully regulated to expand their applications, and they match those of Al2O3 and SiC matrixes, as well as displaying improved mechanical properties. This work promotes applications of YbTaO4 as potential EBCs and provides a new way to regulate the TECs of tantalates.

In this manuscript, we report the density functional theory-based first principles study of the structural and vibrational properties of technologically relevant M′ fergusonite (P2/c)-structured NdTaO4 and SmTaO4 under compression. For NdTaO4 and SmTaO4, ambient unit cell parameters, along with constituent polyhedral volume and bond lengths, have been compared with earlier reported parameters for EuTaO4 and GdTaO4 for a better understanding of the role of lanthanide radii on the primitive unit cell. For both the compounds, our calculations show the presence of first-order monoclinic to tetragonal phase transition accompanied by nearly a 1.3% volume collapse and an increase in oxygen coordination around the tantalum (Ta) cation from ambient six to eight at phase transition. A lower bulk modulus obtained in the high-pressure tetragonal phase when compared to the ambient monoclinic phase is indicative of the more compressible unit cell under pressure. Phonon modes are calculated for the ambient and high-pressure phases with compression for both the compounds along with their pressure coefficients. One particular IR mode has been observed to show red shift in the ambient monoclinic phase, possibly leading to the instability in the compounds under compression.

The 2060 Ma old Palabora Carbonatite Complex (PCC), South Africa, comprises diverse REE mineral assemblages formed during different stages and reflects an outstanding instance to understand the evolution of a carbonatite-related REE mineralization from orthomagmatic to late-magmatic stages and their secondary post-magmatic overprint. The 10 rare earth element minerals monazite, REE-F-carbonates (bastnasite, parisite, synchysite), ancylite, britholite, cordylite, fergusonite, REE-Ti-betafite, and anzaite are texturally described and related to the evolutionary stages of the PCC. The identification of the latter five REE minerals during this study represents their first described occurrences in the PCC as well as in a carbonatite complex in South Africa.The variable REE mineral assemblages reflect a multi-stage origin: (1) fergusonite and REE-Ti-betafite occur as inclusions in primary magnetite. Bastnasite is enclosed in primary calcite and dolomite. These three REE minerals are interpreted as orthomagmatic crystallization products. (2) The most common REE minerals are monazite replacing primary apatite, and britholite texturally related to the serpentinization of forsterite or the replacement of forsterite by chondrodite. Textural relationships suggest that these two REE-minerals precipitated from internally derived late-magmatic to hydrothermal fluids. Their presence seems to be locally controlled by favorable chemical conditions (e.g., presence of precursor minerals that contributed the necessary anions and/or cations for their formation). (3) Late-stage (post-magmatic) REE minerals include ancylite and cordylite replacing primary magmatic REE-Sr-carbonates, anzaite associated with the dissolution of ilmenite, and secondary REE-F-carbonates. The formation of these post-magmatic REE minerals depends on the local availability of a fluid, whose composition is at least partly controlled by the dissolution of primary minerals (e.g., REE-fluorocarbonates).This multi-stage REE mineralization reflects the interplay of magmatic differentiation, destabilization of early magmatic minerals during subsequent evolutionary stages of the carbonatitic system, and late-stage fluid-induced remobilization and re-/precipitation of precursor REE minerals. Based on our findings, the Palabora Carbonatite Complex experienced at least two successive stages of intense fluid-rock interaction.

Thermal barrier coatings (TBCs) play a vitally important role in protecting the hot parts of a gas turbine from high temperature and corrosion effectively. More and more attention has been paid to the performance modification of ZrO2-based ceramics and seeking for new ceramic materials to meet requirements of gas turbine TBCs. The working principle, merits, and demerits of main technologies for coating preparation are elaborated in this paper, and the properties of new ceramic materials are reviewed. It is found that the thermal conductivity, thermal stability, mechanical properties, and other performances of traditional ZrO2-based ceramics could be improved effectively by doping modification. The emphases for new ceramic materials research were put on pyrochlores, magnetoplumbites, rare-earth tantalates, etc. Rare-earth tantalates with great potentials as new top ceramic materials were described in detail. In the end, the development directions of advanced top ceramic coatings, combining doping modification with preparation technology to regulate and control structure property of high-performance ceramic material, were put forward.