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Barium borosilicate (BBS) glass is a potential three-dimensional system packaging and sensor cover material. In this study, we prepared glass samples with different SiO 2 /B 2 O 3 ratios based on the revised model of Dell and Bray and discussed the effect of boron anomaly on dielectric and thermal properties through Raman spectroscopy. The results indicate that the [BO 4 ] tetrahedrons are beneficial in reducing the dielectric constant and dielectric loss to a certain extent, while the improvement in the coefficient of thermal expansion (CTE) is attributed to the depolymerization of the glass network by the [BO 3 ] triangles. After the disappearance of the boron anomaly, a certain amount of dielectric performance is sacrificed in exchange for an increase in the CTE. When the substitution rate of B 2 O 3 for SiO 2 reaches 15.12 mol%, the CTE of the sample increases to 8.43 × 10−6/°C, in addition, the dielectric constant and dielectric loss decrease to 4.90 and 0.0071 (@1 GHz), respectively. In summary, this work provides a suitable method for preparing glass with a high coefficient of expansion and low dielectric loss to address the thermal mismatch effect of different materials in electronic packaging systems. [ABSTRACT FROM AUTHOR]

This work addresses the problem of obtaining of Ca 3 Co 4 O 9+δ -based ceramics with enhanced thermoelectric performance. Phase-inhomogeneous layered calcium cobaltite ceramics with cationic nonstoichiometry were prepared by solid-state reactions method and a field assisted sintering technology (FAST). Comprehensive experimental characterizations were conducted on the prepared bulk samples, focusing on their phase composition, as well as thermal (including thermal expansion, thermal diffusivity, and thermal conductivity), electrical (encompassing electrical conductivity and the Seebeck coefficient), and functional properties (such as power factor and figure-of-merit). The FAST technique allowed to obtain ceramics with low porosity and high electrical conductivity, which increased as the Ca:Co ratio within the samples decreased, while sample phase inhomogeneity considerably increased the Seebeck coefficient. The best thermoelectric performance was demonstrated for cationic nonstoichiometric Ca 3 Co 4.4 O 9+δ , which power factor and figure-of-merit values at 825 °C reached 427 μW⋅m−1⋅K−2 and 0.146, respectively. • Ca 3 Co 4 O 9+δ -based ceramics prepared by field assisted sintering technology possessed low porosity and high conductivity. • Electrical conductivity of bulk samples increased at decreasing Ca:Co ratio. • Phase inhomogeneity of prepared ceramics increased the Seebeck coefficient. • Ca 3 Co 4.4 O 9+δ ceramics showed the best thermoelectric performance. [ABSTRACT FROM AUTHOR]

The thermal barrier coatings (TBCs) system, a pivotal technology for advanced aviation engines and ground gas turbines, mitigates direct interaction between high-temperature gas and high-temperature alloy substrates. In this investigation, a series of high-entropy Eu 2 B 2 O 7 (where B = Y, Yb, Ce, Zr, Hf, Ta, and Nb) oxides were synthesized through solid-state reactions. By manipulating B-site cations and introducing substantial atomic size disparities, as well as mass and charge disorder, we synthesized a highly disordered high-entropy Eu 2 B 2 O 7 oxide. This oxide exhibits a disordered fluorite structure and commendable thermal insulation attributes. The observed thermal conductivity of Eu 2 (Y 0.2 Yb 0.2 Zr 0.2 Nb 0.2 Ta 0.2) 2 O 7 ranges from 0.94 to 1.13 W·m–1·K–1, which can be ascribed to amplified lattice anharmonicity and disorder causing supplementary phonon scattering. In addition, It also shows the thermal expansion coefficient of 10.52 × 10−6 K−1 and high-temperature stability. These results denote that the high-entropy Eu 2 B 2 O 7 oxide may become a prospective contender for thermal barrier coatings and thermal insulators. [ABSTRACT FROM AUTHOR]

Exploring new applications of negative thermal expansion (NTE) materials is a recent research hotspot. In this work, the IV A element Sn was used to tailor the thermal expansion and dielectric properties of NTE material ZrMgMo 3 O 12 , and the samples Zr 1–x Sn x MgMo 3 O 12 (x = 0.05, 0.10, 0.15, 0.20, 0.25) can be used in the field of high-frequency dielectric ceramics. Both the substitution amount of Sn and sintering temperature have a certain effect on the properties of Zr 1-x Sn x MgMo 3 O 12. The coefficients of thermal expansion (CTE) can be adjusted between near zero thermal expansion (ZTE) (−0.24 × 10−6/K−1) and NTE (−8.16 × 10−6/K−1) and become larger toward negative as the amount of Sn increased under the same sintering temperature. The dielectric constants of Zr 1-x Sn x MgMo 3 O 12 can be adjusted in the range of 130∼155, which are about 25 times than ZrMgMo 3 O 12. The dissipation factors of Zr 1-x Sn x MgMo 3 O 12 were adjustable between 4.37 × 10−4 and 5.54 × 10−4, meeting the application requirements of high-frequency dielectric ceramics. This research shows that Sn can adjust the thermal expansion properties and significantly improves the dielectric properties of ZrMgMo 3 O 12 , so that Zr 1-x Sn x MgMo 3 O 12 materials have high value in the field of high-frequency dielectric ceramics. [ABSTRACT FROM AUTHOR]

The properties of rare-earth (RE) monosilicates can be regulated by solid solution engineering based on the mixture rule. The combination and number of RE principals are critical factors for better performances. In the present study, four single-phase equimolar multicomponent RE-monosilicate solid solutions including (Dy 1/3 Er 1/3 Yb 1/3) 2 SiO 5 , (Ho 1/3 Er 1/3 Yb 1/3) 2 SiO 5 , (Y 1/4 Er 1/4 Tm 1/4 Lu 1/4) 2 SiO 5 and (Dy 1/4 Er 1/4 Tm 1/4 Yb 1/4) 2 SiO 5 were synthesized by solid-state reaction and hot-pressing method. The microstructures, thermal and mechanical properties, and corrosion resistance to high-temperature water vapor were systematically investigated. Compared to the single-principal and ternary RE-monosilicates, the quaternary RE-monosilicates exhibited lower thermal conductivity of 1.32 Wm−1K−1 at 400 °C, matched thermal expansion coefficients (3.3 × 10−6/oC ∼ 5.8 × 10−6/oC from 200 °C to 1000 °C) with SiC, and much lower weight loss during water vapor corrosion. The results indicate that the increase of the RE element number can promote the grain growth, lower the thermal conductivity and thermal expansion coefficient, and enhance corrosion resistance. [ABSTRACT FROM AUTHOR]

Pr doped La 2 Zr 2 O 7 (LPZ) TBCs have been deposited by electron beam physical vapor deposition. This work concentrates on the thermophysical properties and microstructure evolution of LPZ/YSZ duplex TBCs before and after thermal cyclic so as to probe into the merit and the application feasibility. The thermal expansion, thermal conductivity and phase structure have been measured and analyzed in comparison to other classical TBCs materials. Typical feathery microstructure and intra-columnar gaps did not provide desired thermal cyclic counts for LPZ/YSZ TBCs. Two principal categories of degradation mechanism limited the cyclic lifetime. The first principal degradation mode is the pulverization of LPZ after thermal cyclic due to the Pr rare earth elements modification in lanthanum Zirconates. Pr instability created the pulverization degradation mode instead of spalling. The second degradation mode is the cracks extension paralleled to interface inside TGO due to the brittle spinel generated by excessive oxidation. This study of thermal properties and degradation mechanism might offer thought and inspiration for other advanced TBCs. [ABSTRACT FROM AUTHOR]

(KMg)3+ co-doped Sc 2 W 3 O 12 ceramics have been prepared via co-precipitation method. Effects of (KMg)3+ co-doping amount and sintering temperature on the phase constitution, microstructure, morphology, and negative thermal expansion (NTE) performance of K x Mg x Sc 2- x W 3 O 12 (0 ≤ x ≤ 1.25) ceramics were studied. Results indicate that: Sc3+ cations can be substituted by (KMg)3+ dual-cations and a composition-induced structural phase transition was observed in K x Mg x Sc 2- x W 3 O 12. For x ≤ 0.25, orthorhombic Sc 2 W 3 O 12 gradually changed into hexagonal K x Mg x Sc 2- x W 3 O 12 and coexisted. Single phase K x Mg x Sc 2- x W 3 O 12 with hexagonal symmetry can be prepared for 0.25 < x ≤ 1. When x ≥ 1.25, (KMg)3+ substitution reaches its solid solution limit in Sc 2 W 3 O 12 , and impurity MgWO 4 formed in the samples. As co-doping amount x increased, the NTE performance of the K x Mg x Sc 2- x W 3 O 12 (0 ≤ x ≤ 1) ceramics gradually enhanced. The coefficient of thermal expansion (CTE) of K x Mg x Sc 2- x W 3 O 12 (0 ≤ x ≤ 1) ceramics enhanced from −2.14 × 10−6 °C−1 to −19.68 × 10−6 °C−1 in 30–700 °C. With the increase of sintering temperature from 800 to 1100 °C, the grains grew up and the density of the K 0.75 Mg 0.75 Sc 1.25 W 3 O 12 ceramics increased as well, and the NTE performance was also improved. The linear CTE of K 0.75 Mg 0.75 Sc 1.25 W 3 O 12 ceramics enhances from −2.15 × 10−6 °C−1 to −14.70 × 10−6 °C−1 in 30–700 °C. [ABSTRACT FROM AUTHOR]

A geometric bowtie design for the purpose of mimicking (matching) and/or mitigating (reducing) the thermal expansion effects between two laterally opposing structures is investigated. A bowtie design is that of two opposing overlapping triangles with farthest sides parallel. This design embodies thermal centering concepts which utilize the relationships of the trigonometric identity known as the law of sines for a triangle from which beneficial thermal properties can be engineered. For validation. The bowtie design is embodied using two separated Zerodur plane mirrors, symmetrically opposed, and each seated in Maxwell-style kinematic couplings of spheres and vee-groves. The vee-grooves form a wheel-like pattern on an aluminum baseplate. The intersection of the vee-grooves is the common overlapping thermal center of both mirror mounts. The refractive-index corrected interferometric measurement of the displacement between these two mirrors shows that even during non-isothermal non-equilibrium transitions and states, the nominal ∼90 μm thermally induced (13 °C) expansion of an aluminum baseplate can be mitigated, being reduced more than 98 % to ∼1.4 μm by mimicking the thermal expansion properties of the mirrors' structural material. Engineering thermally-invariant kinematic bowtie designs using materials having higher thermal expansion coefficients is also described. • Kinematic bowtie design for thermal mimicry and mitigation is described based on law of sines. • Thermal mimicry and mitigation demonstrated for separated parallel Zerodur mirrors. • Thermal expansion mitigation for an aluminum base demonstrated to be reduced to near 1 %. • Non-isothermal non-equilibrium observations are described and considered. • Designs for effective CTE engineering even for zero and negative values are given. [ABSTRACT FROM AUTHOR]

It is difficult to obtain X2-type rare-earth monosilicates that have the advantages of low thermal conductivity and a thermal expansion coefficient that matches that of ceramic matrix composites, and thus, the efficient use of these materials in extreme environments is challenging. In this study, we developed a novel component regulation method, which significantly reduced thermal conductivity and helped achieve a suitable thermal expansion coefficient for monosilicates. Monosilicates have low thermal diffusion coefficients mainly due to the effect of extrinsic phonon scattering mechanisms. We analyzed different extrinsic phonon scattering mechanisms associated with point defect, disorder, grain boundary, lattice distortion, dislocation, and symmetry. • A variety of monosilicates with suitable coefficients of thermal expansion were synthesized. • The thermal conductivity of monosilicates was significantly reduced. • The various extrinsic phonon scattering mechanisms related to point defect, disorder, and more were analyzed. [ABSTRACT FROM AUTHOR]

The excellent thermal properties of diamond/SiC composites are mainly attributed to the addition of diamond particles. In order to further increase the diamond content, a novel preparation method was used to regulate the distribution of bimodal diamond particles. Moreover, in order to achieve better performance, the effects of particle size ratios on the properties were studied. The results show that with the increase of small diamond particle size, the bimodal diamond packing will change from unmixing mechanism to mixing mechanism, and the critical ratio (small/large) of entrance for 400 µm diamond particles is between 0.37 and 0.5. When the particle size ratio is 0.25, the thermal conductivity reaches the maximum, reaching 812.27 W/mK (break through 800 W/mK for the first time). In addition, the influence of particle size ratio on coefficient of thermal expansion is also discussed. [ABSTRACT FROM AUTHOR]

In this study, SiCp-SiO 2 /6061Al composites were synthesized by integrating SiC and SiO 2 particulates into a 6061Al matrix, followed by ball milling and hot isostatic pressing sintering. The impact of ball milling duration on microstructure, mechanical properties, corrosion resistance, and thermal properties was evaluated. After 10 h of ball milling, reinforcement particles were uniformly dispersed, achieving a material density of over 98 %. Extending milling to 15 h enhanced tensile strength to 253.53 MPa and flexural strength to 433.56 MPa, with a maximum elongation at break of 6.4 %. Uniform SiO 2 distribution improved corrosion resistance, evidenced by a self-corrosion potential of −1209 mV and a self-corrosion current density of 53.02 µA·cm−2. After 20 h, the lowest thermal expansion coefficient, 19.87×10−6·K−1, was achieved. However, agglomerated particles after 5 h resulted in inferior thermal properties, including a thermal expansion coefficient of 20.45×10−6·K−1 and thermal conductivity of 94 W·m−1·K−1. The optimal ball milling duration for these composites was determined to be 10 h, balancing performance and cost-effectiveness. • High Performance and Versatility: The composite material exhibits excellent mechanical strength and ductility, with enhanced thermal stability. After 15h of ball milling, it achieved a tensile strength of 253.53 MPa and an elongation at break of 6.4 %, with an average thermal expansion coefficient of 20.26×10−6·K−1 between 25 and 300℃. These properties make it ideal for applications in the aerospace, automotive, and electronics industries. • Enhanced Corrosion Resistance: Uniform SiO 2 distribution after 15 h ball milling significantly enhances corrosion resistance. • Optimized Thermophysical Properties: SiO 2 reinforcements reduce thermal expansion coefficient and enhance the stability of composites; milling time also impacts thermal properties. [ABSTRACT FROM AUTHOR]

Spark plasma sintering (SPS) shows great potential in the fabrication of bulk YH 2- x. For the first time, the high-pressure SPS (HPSPS) of YH 2- x is explored and compared with the routine SPS. It is found that HPSPS remarkably reduces the densification temperature, and thus the thermal dehydrogenation phase transition (δ-YH 2- x → α-Y) and the hydrogen loss of YH 2- x can be avoided. Nearly fully dense δ-YH 1.80 monolith is successfully prepared by HPSPS under 500 MPa at a relatively low temperature of 800 °C. HPSPS is effective in overcoming the thermal dehydrogenation problem during the sintering of YH 2- x. Compared with significant grain growth in the routine SPS, the grain growth in the HPSPS is very limited. In terms of thermal properties, the thermal conductivity of HPSPS prepared YH 2- x is relatively low below 600 °C, then tends to be closed above 600 °C, compared with routine SPS prepared and directly hydrided YH 2- x. The thermal expansion of HPSPS prepared dense YH 2- x is basically consistent with that of directly hydrided bulk. This study provides a valuable reference for the sintering of high-quality δ-YH 2- x and other metal hydrides monoliths. • High-pressure SPS (HPSPS) is used to fabricate dense δ-YH 2- x for the first time. • The differences between routine SPS and HPSPS of dense YH 2- x are clarified. • HPSPS provides a "low-temperature sintering" and very limited grain growth. • The thermal dehydrogenation problem in the sintering of YH 2- x is overcome by HPSPS. [ABSTRACT FROM AUTHOR]

• An SVR model is built to predict the thermal expansion in Ni-based superalloys. • Several alloys are discovered via GA while the model is as fitness function. • Final alloy has low thermal expansion and superior mechanical properties. Traditional Ni-based superalloys are widely used due to their excellent high-temperature performance; however, their high thermal expansion at elevated temperatures limits their further application in the modern aerospace industry. To discover Ni-based superalloys with low thermal expansion for high-temperature environments, such as 900 °C. In this study, we developed a Support Vector Regression (SVR) model with a high coefficient of determination (R2 = 0.84) to predict the coefficient of thermal expansion (CTE) in Ni-based superalloys. Ten samples were selected and produced from a pool of candidates generated via genetic algorithm and the SVR model, revealing that seven of them exhibited superior CTE performance. Notably, the discovered alloy with the lowest CTE (11.0 e-6 °C-1 from RT to 900 °C) presented a remarkable 16.7 % reduction compared to the best performance in existing database. The finally selected alloy demonstrated both low thermal expansion and superior mechanical properties compared to traditional superalloys with low thermal expansion. [ABSTRACT FROM AUTHOR]

LaMgAl 11 O 19 (LMA) with magnetoplumbite structure is a promising thermal barrier material due to its excellent thermal properties. In this work, Zn-doped LMA materials were studied in order to improve the thermal performance, and LaZn x Mg 1-x Al 11 O 19 (x = 0, 0.1, 0.3, 0.5, 0.7, 1.0) were prepared by sol-gel method. The as-synthesized powder materials possess pure LMA phase and show the morphology of hexagonal plates. X-ray photoelectron spectroscopy result shows that there are AlO 4 tetrahedra and AlO 6 octahedra units in the target materials, and Zn2+ ions replace Mg2+ ions to occupy the tetrahedral position of magnetoplumbite structure. The composition LaZn 0.3 Mg 0.7 Al 11 O 19 material exhibits the lowest thermal conductivity of 0.38 W/(m·K) at 1000oC while maintaining a high coefficient of thermal expansion (10.86 × 10−6 K−1). Therefore, the thermal properties of LMA materials can be improved by adding an appropriate amount of Zn ions. • LaZn x Mg 1-x Al 11 O 19 (x = 0–1.0) were prepared by sol-gel method. • Electronic structure of Zn-doped LaMgAl 11 O 19 materials were studied by X-ray photoelectron spectroscopy. • Zn doping has greatly effect on the thermal performance of the LaMgAl 11 O 19. • LaZn 0.3 Mg 0.7 Al 11 O 19 material exhibits the lowest thermal conductivity of 0.38 W/(m·K) at 1000oC. [ABSTRACT FROM AUTHOR]

[Display omitted] • Simple theoretical equation of state for the dependency of size, shape and temperature of the nanostructures. • Extension of Qi and Wang model for equation of state for nanoparticle. • The compression ratio (V/V 0) increases with temperature across nanoparticles of various sizes. • The computed data for volume compression ratio are in good agreement with available experimental data. Simple theoretical equation of state has been derived to study the dependency of size, shape and temperature of the nanostructures. Qi and Wang model of equation of state (EoS) is extended to study the size and shape dependent compression ratio for Se nanoparticle. The compression ratio (V/V 0) increases with temperature across nanoparticles of various sizes. The computed data for volume compression ratio are compared with available experimental data and found in good agreement. A good agreement between theoretically calculated and experimental result proves the usefulness of the model to study the thermal properties of nanoparticles. [ABSTRACT FROM AUTHOR]

The structural, elastic, and thermodynamic characteristics of the GaCaF 3 and GaSrF 3 halide perovskites have been predicted for the first time, using ab initio pseudopotential plane wave calculations. The equilibrium lattice parameters are in good agreement with previously documented results. Both compounds exhibit substantial thermodynamic and mechanical stability. The single-crystal and polycrystalline elastic properties and related properties have been examined. GaCaF 3 exhibits higher hardness than GaSrF 3. The temperature dependence of the lattice parameter, bulk modulus, volume thermal expansion coefficient, heat capacity, and Debye temperature, have been computed using ab initio calculations combined with the quasi-harmonic Debye model. • With density functional theory (DFT) to study properties GaCaF 3 and GaSrF 3 halide perovskite compounds. • Both materials are thermodynamically and mechanically stable, and have a ductile nature. • GaCaF 3 is harder than GaSrF 3. • Both crystals exhibit noticeable elastic anisotropy. • Temperature dependence of some physical parameters is successfully determined through the quasi-harmonic Debye model. [ABSTRACT FROM AUTHOR]

At room temperature, monoclinic In 2 W 3 O 12 ceramics exhibits positive thermal expansion. However, it transforms into an orthorhombic phase above 253 ℃, and then stably exhibits negative thermal expansion (NTE). In this work, to improve the NTE performance and extend the NTE temperature range of In 2 W 3 O 12 , the K x Mn x In 2-x W 3 O 12 (0≤x≤0.5) ceramics were synthesized via the solid-state reaction method. The effects of (KMn)3+ double cation co-doping on the composition, microstructure, and thermal expansion behaviors of In 2 W 3 O 12 ceramics were studied using XRD, Raman, XPS, SEM, and TMA. The results show that (KMn)3+ cations can replace In3+ in In 2 W 3 O 12 ceramics. As the (KMn)3+ doping amount increases, monoclinic In 2 W 3 O 12 gradually changed into monoclinic K x Mn x In 2-x W 3 O 12. Meanwhile, the grains grow up and the density of K x Mn x In 2-x W 3 O 12 ceramics was increased. Pure monoclinic K x Mn x In 2-x W 3 O 12 ceramics were prepared when x rises to 0.25 and 0.4. Among them, the thermal expansion coefficient of K 0.4 Mn 0.4 In 1.6 W 3 O 12 ceramics in 100–700 ℃ is as high as -17.83×10-6 ℃-1, which was significantly improved compared to In 2 W 3 O 12 ceramics. In addition, the structural phase transition of In 2 W 3 O 12 ceramics around 253 ℃ was gradually eliminated and the NTE temperature range was widened. Double cation (KMn)3+ co-doping effectively improves the NTE performance of In 2 W 3 O 12. • (KMn)3+ co-doped In 2 W 3 O 12 ceramics were prepared by solid-state method. • (KMn)3+ co-doping induces a phase transition in In 2 W 3 O 12 ceramics. • Monoclinic K x Mn x In 2-x W 3 O 12 ceramics show stronger NTE as x increases. [ABSTRACT FROM AUTHOR]

The limited efficiency of traditional trial-and-error experiments has impeded the development and application of high-entropy fluorite oxides in thermal insulation coatings. To solve this problem, a novel entropy descriptor based on first principles is presented to help select candidate components for synthesizing high-entropy fluorite structure oxides. Results show that the compatibilities of 10 single-phase high-entropy fluorite oxides can be accurately predicted based on entropy formation ability. In the studied (Zr, Hf, Pr, La, X) O 2-δ system, a correlation between thermal characteristics and size/mass differences was established by designing the size and mass of X. Specifically, we found that the thermal conductivity is more strongly correlated with the difference in atomic mass, while the coefficient of thermal expansion is strongly correlated with the difference in atomic size. X-ray photoelectron spectroscopy (XPS) analysis shows that the concentration of oxygen vacancy can effectively reduce the thermal conductivity of high-entropy fluorite oxides. In addition, the values of hardness, elastic modulus and thermal conductivity of five single-phase fluorite oxides are successfully predicted by first principles calculation, and the differences between these values and the experimental results are small, which provides a prospective significance for the performance prediction of high-entropy fluorite oxides. Our findings provide a strategy for customizing high-entropy fluorite single-phase oxides with suitable properties to meet the performance requirements of thermal barrier coatings (TBCs). • The DFT calculation provides an entropy descriptor to evaluate the comfiability of high-entropy single-phase fluorite oxides based on their entropy formation capacity. • The hardness, elastic modulus and thermal conductivity of the studied sample are obtained by DFT calculation, and the difference between them and the experimental values is small. • In the (Zr, Hf, Pr, La, X)O 2-δ system, the atomic size difference and atomic mass difference of five single-phase samples were quantified, and their thermal conductivity and thermal expansion values were correlated. [ABSTRACT FROM AUTHOR]

The angle of the light receiving panel in traditional optical equipment is fixed. When the light does not shine vertically onto the panel, there will be a problem of energy density loss due to oblique incidence. In this article, we prepared an intelligent responsive light-driven bimorph soft actuator using the thermal expansion properties of polydimethylsiloxane. Intelligent bending photothermal converter can be achieved by placing a photothermal converter at the top of the device. The device adopts a hollow cylindrical structure to achieve omni-directional response to light, and has the advantages of fast response speed, high tracking accuracy, and strong repeatability. When light is irradiated from a 40 ° direction, the device can be bent in the direction of illumination, aligning the top photothermal converter with the direction of illumination, proving that the light-driven soft actuator we have prepared can effectively recover energy density loss of oblique incidence. [Display omitted] • Light-driven actuator was used to realize the response to light. • Cylindrical structure was used to realize omni-directional response to light. • Photothermal converter was used to simulate the optical equipment. • Successfully recovered the oblique-incidence energy-density loss. [ABSTRACT FROM AUTHOR]

The present work focuses on the role of NiB and ZrB 2 addition on density, structural evolution, mechanical and thermal properties of 90W-6Ni-4Co (wt%) heavy alloys. The investigated tungsten heavy alloys were sintered at 1485 °C and 1500 °C with a holding time of 75 min in H 2 atmosphere. Compared to the base alloy 90W-6Ni-4Co, the NiB-substituted alloys showed improved densification at both sintering temperatures. An in-depth study of the phase and microstructure of the 1500 °C sintered samples was carried out. X-ray diffraction analysis confirmed the presence of ZrO 2 in ZrB 2 containing WHAs. Microstructural analysis affirms that ZrB 2 incorporation attributes for grain size refinement in sintered alloys. Furthermore, the elephant foot formation in the sintered samples was avoided by incorporating NiB individually or in combination with ZrB 2 dispersoids. The distortion parameter (δ) of the samples sintered at 1500 °C was found to be decreased from 24.83 (0 wt% ZrB 2) to 6.36 (2 wt% ZrB 2). On the other hand, the combined addition of NiB and ZrB 2 provides better shape retention with δ =2.82 for the tungsten heavy alloys with 3 wt% NiB and 2 wt% ZrB 2. The maximum compressive stress of ∼2000 MPa was obtained in the 89W-6Ni-4Co-1ZrB 2 samples. The maximum and minimum bulk hardness of 432 ± 5 HV 3 and 365 ± 9 HV 3 was obtained for 88W-3Ni-3NiB-4Co-2ZrB 2 and 90W-6Ni-4Co heavy alloys. The coefficient of thermal expansion of the 90W-6Ni-4Co alloy was found to be the highest (7.65 × 10−6 /°C), which was reduced to 7.1 × 10−6 /°C and 6.8 × 10−6 /°C with the incorporation of 1 and 2 wt% ZrB 2 respectively. W-rich channels were noticed in the microstructure of 1500 °C sintered samples. Overall, W-Ni/NiB-Co-ZrB 2 alloys are very effective in enhancing the mechanical properties and distortion behavior compared to W-Ni-Co alloys. • ZrB 2 addition refines W grain size in sintered alloys. • XRD and EDS analysis confirm the partial transformation of ZrB 2 to ZrO 2. • A distinct channel like structure was noticed in NiB-substituted sample. • The liquid phase sintered W-Ni/NiB-Co-ZrB 2 alloys prevent shape distortion. • ZrB 2 -containing heavy alloys offer reduced thermal expansion coefficient. [ABSTRACT FROM AUTHOR]

• Novel method is applied to fabricate SiC fiber-reinforced Al matrix composites. • SiC fibers with high volume fraction is introduced into the Al matrix uniformly. • SiC fiber significantly improve the mechanical properties of Al matrix composites. • Coefficient of thermal expansion decreases with increasing the SiC fibers' content. Combining the colloidal dispersion method with the squeeze melt infiltration technique, aluminum matrix composites with different volume fractions of silicon carbide fiber were fabricated at 680 °C under vacuum. Microstructure analysis found that composite presented a dense structure and fibers were homogeneously distributed in matrix. The hardness, yield strength and elastic modulus of the composite monotonically increased with increasing the volume fraction of fiber. The highest flexural strength for composite with 10 vol% SiC fiber was achieved. The improved mechanical properties could be attributed to the dispersion strengthening and enhanced load transferring ability by fibers as well as the dislocation strengthening. On the other hand, the coefficient of thermal expansion of composites was measured at temperature up to 400 °C. It was found that the uniform introduction of silicon carbide fiber could significantly low the CTE of aluminum matrix composite, which could be attributed to the low CTE of SiC fiber and good fiber–matrix interface bonding. [ABSTRACT FROM AUTHOR]

In the development for advanced nuclear fuels for LWRs, the focus has traditionally centered on a limited array of materials like doped-UO 2 , UN, and U 3 Si 2 , leaving the vast majority of potential uranium compounds unexplored. To expand the search and expedite the discovery of advanced LWR fuels, we developed a machine learning (ML) classification model dedicated to identifying uranium compounds with excellent thermal conductivity. However, the model's predictive accuracy and the feasibility of such an ML-assisted approach to advanced nuclear fuel discovery have yet to be empirically validated. Therefore, this study examines the thermal properties of two uranium compounds, UFe 3 B 2 and USiNi, that are predicted to outperform UO 2 at high temperatures. Our findings confirm that the model precisely predicted the thermal conductivities of both compounds, thereby adding credibility to its reliability. However, the experimental process unveiled several challenges, such as the fabrication of single-phase USiNi and microcrack-free UFe 3 B 2 samples, which our ML model, focused primarily on thermal conductivity, could not anticipate. These challenges underscore the need for a more comprehensive ML framework that considers the intricacies of sample fabrication. This advancement is crucial for the more efficient development of practical, accident-tolerant, advanced LWR fuels. • Validated ML model's predictions for uranium compounds' thermal conductivity. • First report of UFe 3 B 2 and USiNi thermophysical and mechanical properties. • Identified unforeseen experimental challenges beyond ML prediction. • Emphasized need for comprehensive ML framework for advanced nuclear fuel development. [ABSTRACT FROM AUTHOR]

The current work presents a theoretical study of the physical properties of several FePt 2 ordered structures through first-principles calculations, including structural, magnetic, electronic, mechanical, phonon and thermal properties. The structural stabilities are certified by the enthalpies of formation, elastic constants, and phonon dispersion relationships. The tetragonal I 4/ mmm structure is energetically favorable compared to other types FePt 2 structures including Cmcm , Immm , P 6 3 / mmc and P 4/ nmm structures. The electronic density of states and the contributions of each d -orbital electron to the magnetic moment are analyzed to understand their magnetism. The bulk modulus B values of these FePt 2 structures are similar, but the Young's modulus E and shear modulus G as well as the elastic anisotropy are quite different. The thermal properties at finite temperature are estimated by the quasi-harmonic approximation. The I 4/ mmm structure has higher isothermal bulk modulus, lower thermal expansion coefficient and weaker thermal expansion anisotropy, which is more suitable for high temperature applications than other structures. Also, the sequence of thermal expansion anisotropy is P 4/ nmm > Immm > Cmcm > I 4/ mmm (≈ P 6 3 / mmc). [ABSTRACT FROM AUTHOR]

• The effect of CNTs on the thermal expansion coefficient (CTE) of FSC at early age was investigated. • A time-varying model of FSC at early age CTE was developed based on maturity theory. • The time-varying CTE can reflect the actual thermal cracking situation of FSC. • The addition of 0.1 wt% CNTs can reduce the early CTE of FSC and improve its crack resistance. Temperature stresses are a major cause of thermal cracking in face slab concrete (FSC) at an early age. Time-varying coefficient of thermal expansion (CTE) can reflect the real thermal cracking of FSC. Carbon nanotubes (CNTs) can improve the mechanical properties of concrete, but its thermal cracking performance is rarely reported. In this study, CTE of FSC at an early age was investigated based on the maturity theory. The mechanism of CNTs on the CTE of FSC at early age was revealed, and a time-varying model for CTE at early age was developed. The results showed that CNTs can effectively reduce the CTE of FSC at an early age and can significantly improve the cracking resistance of FSC at early age. [ABSTRACT FROM AUTHOR]

• Cu/Fe/Kovar composites have a much better thermal conductivity than Kovar alloys. • Good thermal conductivity of Cu/Fe/Kovar composites is attributed to the formation of Cu network. • Fe interlayer decreases the mutual diffusion between Cu coating and Kovar alloy matrix. To improve the thermal conductivities of Kovar alloys (4J50), Fe and Cu coatings were prepared on surfaces of one of Kovar alloys (4J50) powders by electroless plating and Cu/Fe/Kovar composites were hot-pressing sintered. The Fe interlayer is prepared to decrease the mutual diffusion between the Cu coating and the Kovar alloy matrix. Since the existence of Cu network in the composites, the composites present a better thermal conductivity than Kovar alloys. The Cu/Fe/Kovar composites containing 10 wt% and 20 wt% Cu have a thermal conductivity of 24.7 W/(m·K) and 25.8 W/(m·K), respectively, which is 48 % and 54 % higher than that of the Kovar alloy (16.7 W/(m·K)). Due to the presence of Cu network, the coefficients of thermal expansion of the composites is slightly higher than that of the Kovar alloy. The method reported in this study can be also applied to improve the thermal conductively of other Kovar alloys. [ABSTRACT FROM AUTHOR]

The determination of the thermoelastic properties of polyimide (PI) fibers is important for their applications, however, these properties are difficult to measure directly, especially the transverse thermoelastic properties. Here, the transverse thermoelastic properties of PI fibers, including transverse Young's modulus (2.12 GPa), shear modulus (0.94 GPa), Poisson's ratio (0.05), and coefficient of thermal expansion (45.68 μm/m°C), were estimated by combining dynamic and static thermo-mechanical techniques, as well as various relevant micromechanical models. The transverse Young's modulus of PI fibers was only 1/46th of the longitudinal one, and the transverse coefficient of thermal expansion of PI fibers was positive, unlike the longitudinal one, which was negative, showing the typical anisotropy of PI fibers. Finally, the thermoelastic properties of the PI fibers were in turn used to predict the thermoelastic behavior of the PI fiber-reinforced composites, thus validating their effectiveness. [Display omitted] [ABSTRACT FROM AUTHOR]

• An efficient scheme is developed to investigate anisotropic thermal expansion. • The anisotropic thermal expansion and thermomechanic properties of α-phase group-VA monolayers (α-P, α-As, α-Sb and α-Bi) are investigated systematically. • It is found from α-P to α-Bi monolayer, thermal expansion becomes more significant. • The macroscopic Grüneisen parameters and elastic constants are investigated to understand the underlying physical mechanism of thermal expansion properties. The theoretical investigations of anisotropic thermal expansion are quite few as the huge computational cost. In this work, a scheme of Taylor expansion for phonon free energy is introduced to investigate anisotropic thermal expansion, which can save lots of computational cost. The anisotropic thermal expansion and thermomechanic properties of α-phase group-VA monolayers (α-P, α-As, α-Sb and α-Bi) are investigated systematically by using the first-principles calculations. It is found all the four monolayers show remarkably anisotropic thermal expansion, and very different from each other. In α-As and α-Bi monolayers, remarkable negative thermal expansion appears along armchair direction. From α-P to α-Bi monolayer, the absolute value of linear thermal expansion coefficient becomes larger. In particular the linear thermal expansion coefficient of α-Bi is in terms of order of magnitude close to 10−4 K−1 at 300 K. The macroscopic Grüneisen parameters and elastic constants are also investigated to unveil the underlying physical mechanisms. [ABSTRACT FROM AUTHOR]

The first thermal expansion measurements of the 4H and 6H polytypes of SiC below room temperature are reported. The measurements were carried out on single-crystal specimens using high-resolution capacitive-based dilatometry. For both polytypes, the thermal expansion coefficient is below 2.4 × 10−6 1/K near room temperature. No phase transitions are observed over the 5 K to 340 K temperature range of the measurements. The thermal expansion coefficient α of 4H SiC is slightly anisotropic for measurements parallel and perpendicular to the crystallographic c axis with α | | about 2.2 × 10−7 1/K larger than α ⊥ near room temperature. For 6H SiC no discernible anisotropy is observed. The differences in anisotropy can be understood by considering the ratio of hexagonal to cubic bonds of each polytype. Narrow regions with negative thermal expansion that are within the limits of our resolution (∼ 1 × 1 0 − 8 ) are observed in the vicinity of 30 K for both specimens. Tabulated data, polynomial fits, fit parameters, and comparison to data based on lattice-parameter measurements are provided. • First measurements of the thermal expansion coefficients of 4H and 6H SiC. • Temperature range of the study is 5 K to 340 K. • These high-resolution data offer much better resolution than previous measurements above room temperature using diffraction methods. • The thermal expansion coefficient of both 4H and 6H polytypes of SiC are extremely small, which may be important for specific applications. [ABSTRACT FROM AUTHOR]

This work reports on the synthesis, mechanical, and thermal properties of in situ AlN/Al-12Si composite through laser powder bed fusion (LPBF) by blending Al-12Si powder with 5 vol% nano-sized BN particles. Incorporating nano-BN particles results in (i) formation of thermally stable AlN phase, preventing Si diffusion and breakdown of cellular structure, (ii) improvement of compressive yield strength (CYS), and (iii) reduction in coefficients of thermal expansion (CTE) and thermal conductivity. In addition, compared to Al-12Si alloy, the composite exhibits grain refinement from 38.8 to 1.2 μm in size, and the alteration of columnar grains (Al-12Si) to equiaxed grains (AlN/Al-12Si). At annealing temperatures above 573 K, the CYS of the unadulterated Al-12Si alloy had a ∼ 2.1 times greater reduction (from 285 to 200 MPa) compared to that of the composites (from 301 to 260 MPa). The formation of the AlN phase mitigates the significant reduction in CYS. The CTE of Al-12Si and AlN/Al-12Si are 27.3 × 10−6 K−1 and 24.3 × 10−6 K−1 respectively. There is good agreement between the measured CYS results and the calculated strengthening mechanisms. This work offers both theoretical insights and experimental data to support the use of LPBF AlN/Al-12Si composite in low- and moderate-temperature applications. • Novel in situ AlN/Al-12Si composite is successfully fabricated by laser powder bed fusion. • AlN phase generate from the reaction between BN particle and Al-12Si during laser melting. • AlN/Al-12Si composites have a higher compressive yield strength and lower thermal conductivity. • AlN phase leads to the grain refinement, improving the compressive yield strength. • AlN phase mitigates the reduction in coefficients of thermal expansion at medium temperature. [ABSTRACT FROM AUTHOR]

The lattice structure and elastic properties of Dy 2 Hf 2 O 7 at 0 K and 0–40 GPa are calculated by using first-principles methods. The results show that the calculated structural parameters are in good agreement with the experimental values. The elastic constants increase with the increase of pressure, and all the elastic constants satisfy the Born criterion, that is, the Dy 2 Hf 2 O 7 crystal is kinetically stable within the range of the calculated conditions. In addition, the thermodynamic properties of Dy 2 Hf 2 O 7 crystal at different temperatures (0–2000 K) and pressures (0–40 GPa) are calculated by using the quasi-harmonic Debye model, and the temperature-pressure dependence of thermodynamic properties, such as the heat capacity, coefficient of thermal expansion, and Debye temperatures, is obtained and compared with the experimental values. We also obtain the melting point and hardness of Dy 2 Hf 2 O 7 compound by using empirical formulas in the literature. • Elasticity and thermodynamic properties of cubic Dy 2 Hf 2 O 7 under high temperature and pressure are obtained. • Mechanical stability is testified and predicted by analysis of elastic constants in wide pressure range of 0–40 GPa. • The hardness and melting point and anisotropy of Dy 2 Hf 2 O 7 compound have been obtained first time. • This study presents the inaugural prediction of the interfacial stability of dysprosium hafniate in a helium environment. [ABSTRACT FROM AUTHOR]

[Display omitted] • The feasibility of obtaining low thermal expansion (LTE) Fe-Ni alloys using T-WAAM is investigated. • Deposition mode affects the stability of the melt pool and the resulting chemical composition. • Stability in deposition and composition is achieved with the continuous metal transfer mode during the T-WAAM process. • The as-deposited LTE alloys exhibit thermal properties comparable to the conventionally produced alloys. The binary Fe–Ni system offers alloys with notably low linear coefficients of thermal expansion (CTE), contingent upon their Ni content. In this respect twin-wire arc additive manufacturing (T-WAAM) presents the opportunity of in-situ alloying through the simultaneous feeding of two metal wires into a weld pool to obtain desired alloy compositions. This study aims to deposit a graded wall with Ni contents targeted at 42, 46, and 52 wt% in the building direction of the wall, along with a block comprising of 46 wt% Ni, employing the T-WAAM approach. The results show effective incorporation of additional Ni into the weld pool and geometrically stable weld beads in the continuous metal transfer mode during the T-WAAM process. This mode led to the defect-free and chemically stable deposition of the graded wall and the block with average Ni contents of 42.3 ± 1.1, 45.8 ± 1.4, 52.6 ± 0.8 wt%, and 46.4 ± 0.9 wt%, respectively. The measured Curie temperatures of the as-deposited alloys and the mean CTE values of alloy 46 were found to be comparable to the commercial alloys. In summary, this study validates the feasibility of in-situ deposition of low thermal expansion alloy compositions, thereby enabling the possibility of on-demand thermal expansion properties. [ABSTRACT FROM AUTHOR]

Invar 36 alloy manufactured via the laser powder bed fusion (LPBF) process have attracted interest for their excellent low expansion properties. The properties of Invar 36 alloy, particularly thermal expansion, are highly sensitive to variations in process parameters. However, the effect of process parameters on microstructure and properties has not been systematically studied. This study examines the microstructure, mechanical properties, and coefficient of thermal expansion (CTE) of Invar 36 alloy under various processing parameters with different volumetric energy densities (VED). The results demonstrate that VED variations significantly impact the microstructure, mechanical properties, and CTE. Increasing VED leads to larger grain size and higher high angle grain boundaries, while geometric dislocation density and Taylor factor do not exhibit a linear relationship. At 89.29 J/mm3 VED, the Invar 36 alloy displays the optimal yield strength (405.4 MPa), tensile strength (489.3 MPa), and elongation (43.3%). The CTE meets the ASTM F1684 standard for all specimens. Lower relative density corresponds to smaller CTE, with the lowest CTE achieved at VED of 41.67 J/mm3. Furthermore, the influence of porosity on CTE diminishes with rising temperature. This research opens up the possibility of process parameters optimization for improved CTE and mechanical properties in as-printed Invar parts. [ABSTRACT FROM AUTHOR]

Recent progress combining micromechanics and machine learning holds promise for accurately and rapidly predicting the mechanical behavior of complex composite materials. This study extends the Deep Material Network (DMN), a binary-tree network trained on linear direct-numerical-simulation data, to predict the thermo-elasto-viscoplastic behavior of composites. This extension incorporates the thermal expansion properties homogenization into the network's building blocks and expands the online formulation to consider thermal boundary conditions. By comparing various implementations of these building blocks, we demonstrate the network's extrapolation to thermomechanical problems. We then show how this extended DMN can be applied to uncertainty quantification and inverse design problems. [ABSTRACT FROM AUTHOR]

• The structural, and physical properties of MAX phase Zr 2 MSiC 2 (M = Ti or V) compounds have been determined using the first-principles method. • The melting temperature, Debye temperature, and minimum thermal conductivity confirm their use in harsh environments and as thermal barrier coatings. The Wien2K code, which utilizes density functional theory (DFT) first-principles method, is employed to examine the physical features of MAX phase Zr 2 MSiC 2 (M = Ti or V). Furthermore, this method is also used to determine the Debye temperature and Vickers hardness of the compound. The computed structural parameters are highly realistic. Calculation of the formation energy, elastic constants C ij , and phonon band structure has confirmed with certainty compounds are thermodynamically, and mechanically stable. On the other hand, both Poisson's and Pugh's ratios reveal the compound's brittleness. The substance exhibits considerable elastic anisotropy. According to the electronic structure, our compounds contain a combination of ionic and metallic bonding. The melting temperature, Debye temperature, and minimum thermal conductivity confirm their use in harsh environments and as thermal barrier coatings. The fact that the rate of increase in Cv and the thermal expansion coefficient is the same in both compounds under varying pressure and temperature conditions suggests that they possess similar properties. The results that are being reported here increase the possible application of Zr 2 MSiC 2 for future engineering. [ABSTRACT FROM AUTHOR]

Thermodynamic properties of ternary ceramic TiCN are studied by first-principles calculation combined with the Debye Einstein model, which considers the contribution of 3n−3 optical frequencies at the Γ point; Debye Grüneisen model, which treats optical frequencies as acoustic ones; and quasiharmonic approximation(QHA), which is the most prevalent method in prediction of phonon dispersion and thermal properties. No imaginary frequency shows that TiCN has dynamic stability, and negative formation energy indicates the thermodynamic stability. Particularly, TiCN has low thermal expansion coefficient, which rises quickly firstly and then gradually as temperature rises. The study of bulk modulus shows that TiCN possess excellent resistance to the volume thermal deformation. For temperature effects of thermal expansion coefficient, heat capacity and entropy, the obtained results show that Debye Einstein model are apparently closer to the QHA at low temperatures. Our present results provide guideline for exploration of thermal properties of multicomponent materials. [ABSTRACT FROM AUTHOR]

We introduce the concept of physics-guided transfer learning to predict the thermal conductivity of an additively manufactured short-fiber reinforced polymer (SFRP) using micro-structural characteristics extracted from tensile tests. Developing composite manufacturing digital twins for SFRP composite processes like extrusion deposition additive manufacturing (EDAM) require extensive experimental material characterization. Even the same material system printed on different EDAM systems can result in significant changes to the printed micro-structure, affecting the mechanical and transport properties. This, in turn, makes characterization efforts expensive and time-consuming. Therefore, the objective of the paper is to address this experimental bottleneck and use prior information about the material manufactured in one extrusion system to predict its properties when manufactured in another system. To enable this framework, we assume that changes in properties of the same material when manufactured in different systems arise solely due to microstructural changes. To that end, we present a Bayesian framework that can transfer thermal conductivity properties across extrusion deposition additive manufacturing systems. While we discuss the transfer of thermal conductivity properties, the development is such that the framework can be used for the transfer of other properties that depend on microstructural characteristics defined in the manufacturing process. These include the coefficient of thermal expansion, viscoelastic properties, etc. The framework begins by using thermal conductivity data of the composite printed in one extrusion system to probabilistically infer the constituent thermal properties of the fiber and the polymer. Next, by conducting limited tensile tests of the same material printed in another extrusion system, we infer its orientation tensor. Finally, the inferred constituent thermal conductivity properties and the inferred orientation tensor are coupled using a micromechanics model to predict the thermal conductivity properties of the composite printed in the second extrusion system. We experimentally verify the predictions and show that our method provides a reliable framework for transferring material properties while accounting for epistemic and aleatory uncertainties. • A probabilistic framework to transfer material information across manufacturing systems. • A framework to account for surrogate uncertainty in parameter inference. • Demonstrate transfer of thermal conductivity across additive manufacturing systems. • Applications to transfer other properties including coefficient of thermal expansion. [ABSTRACT FROM AUTHOR]

A study of heat capacity, thermal dilatation and sensitivity to hydrostatic and uniaxial pressure was carried out on single-crystal and ceramic samples of NH 4 HSeO 4. The main parameters of low-temperature successive phase transitions B 2 (T 1) ↔ incommensurate IC (T 2) ↔ ferroelectric P 1 (T 3) ↔ non-ferroelectric did not depend on the type of samples. The behavior of the volumetric strain and the results of direct measurements of T 3 (p) contributed to the resolution of the longstanding problem associated with the ambiguity of the sign of the corresponding volumetric baric coefficient. The role of thermal expansion anisotropy in the formation of the piezocaloric effect (PCE) near the ferroelectric phase transition at T 3 has been studied. Due to the strong difference in the linear baric coefficients, the main contribution to the barocaloric effect (BCE) comes from the inverse intensive and extensive PCE associated with the a- axis. Compared to a single crystal, ceramics demonstrate lower BCE values, which, however, exist in a wider temperature range, which leads to close values of integral caloric parameters. The strong decrease in both BCE and PCE at low-temperature transformations in NH 4 HSeO 4 compared to the ferroelectrics NH 4 HSO 4 and NH 4 NH 4 SO 4 is associated with a small change in entropy during three low-temperature phase transitions, ΣΔ S i = 2.52 J/mol∙K, which is a consequence of a high degree of structural ordering in selenate as a result of a high-temperature transformation at T 0 between the superionic and B 2 phases, accompanied by a giant change in entropy, Δ S 0 ≈ R ln21. [Display omitted] • Size/surface as well as anisotropy effect on thermal properties of NH 4 HSeO 4. • Gigantic entropy change associated with transformation to superionic phase. • Expansion of the temperature range of the ferroelectric phase under pressure. • Large piezocaloric effect at P 1↔paraelectric transition under very low pressure. • NH 4 HSeO 4 is a decent refrigerant for cooling devices with low heat dissipation. [ABSTRACT FROM AUTHOR]

Charge carrier concentration and temperature dependences of the Seebeck coefficient, electrical conductivity, electronic thermal conductivity, the power factor and figure of merit of LuVCo 2 Sb 2. [Display omitted] • The study examines the structural properties of LuXCo 2 Sb 2 alloys (X = V, Nb, and Ta) in their orthorhombic structure. • These alloys exhibit strong mechanical stability. • These compounds exhibit strong thermoelectric potential with ZT exceeding 0.5 at 500 K. We used the pseudopotential plane wave approach, as implemented in the Quantum Espresso program, to investigate the impact of X atoms (V, Nb, and Ta) on the physical properties of LuXCo 2 Sb 2 double half Heusler alloys. We determined the equilibrium structural parameters, including the crystal lattice parameters, atomic position coordinates, and bulk modulus, with and without including the spin-orbit effects. The predicted single-crystal elastic constants (C ij) show that the title compounds are mechanically stable with a pronounced elastic anisotropy. The bulk modulus, shear modulus, Young's modulus, Poisson coefficient, Debye temperature, and Vickers hardness coefficient were deduced from C ij via the Voigt-Reuss-Hill approximations. We also determined the variations of some macroscopic physical parameters as functions of temperature and pressure, namely the thermal expansion coefficient, lattice thermal conductivity, heat capacity at constant volume, Debye temperature and entropy. The considered alloys demonstrate special thermal properties under pressure and heat conditions, specifically, their low thermal expansion coefficient and lattice thermal conductivity; their thermal expansion coefficient is lower than 4.5 × 10−5 K−1 at 1000 K, and lattice thermal conductivity don't exceed 1 W.m−1 K−1 for temperatures higher than 300 K. Furthermore, we investigated the temperature and charge carrier concentration dependencies of some thermoelectric coefficients. The results of this study reveal the potential of the considered compounds for achieving a figure of merit greater than 0.5 at a temperature of 500 K and a doping concentration of 1020 cm−3. [ABSTRACT FROM AUTHOR]

The novel rare earth monosilicates (xRE 1/x) 2 SiO 5 (RE=Yb, Tm, Er, Y, Dy and Tb, x = 2–6) were prepared in order to establish the relationship between configurational entropy and lattice distortion, and the effect of configurational entropy on their properties was investigated. The results showed that the lattice distortion of (xRE 1/x) 2 SiO 5 increased gradually with the increase of configurational entropy, but the multi-principal component solid solution tended to form a highly symmetrical crystal structure when the configurational entropy was large enough, thus inhibiting the lattice distortion. (5RE 1/5) 2 SiO 5 had a maximum lattice distortion, which leaded to a relatively low thermal conductivity and coefficient of thermal expansion, and good CMAS corrosion resistance. • The effect of configurational entropy on microstructure and properties was investigated. • (5RE 0.2) 2 SiO 5 ceramic had a maximum lattice distortion. • (5RE 0.2) 2 SiO 5 ceramic presented the relatively good thermal properties and CMAS corrosion resistance. [ABSTRACT FROM AUTHOR]

To pursue superior yield strength and low thermal expansion characteristic of Fe-36Ni Invar alloy, Fe-36Ni Invar alloys containing various cerium (Ce) contents (0 wt%, 0.0050 wt%, 0.0170 wt%, and 0.0360 wt%) were prepared by vacuum induction melting, followed by the heat treatment process. With increasing Ce content, the evolution of the second-phase particles followed the sequence: MnO-MnS (0% Ce) → MnO-MnS + Ce 2 O 3 (0.0050% Ce) → Ce 2 O 3 + Ce 2 O 2 S (0.0170% Ce) → Ce 2 O 3 + Ce 2 O 2 S + Ni 5 Ce (0.0360% Ce). The results indicated that the grain size and the fraction of annealing twins (f AT) were fairly sensitive to the Ce content. The smallest average grain size (d ¯) and the highest f AT were obtained by adding 0.0170% Ce. The small addition of Ce was beneficial to the improvement of strength and low thermal expansion behavior. In particular, 0.0170% Ce alloy achieved the optimal combination properties. However, the excessive addition of Ce (0.0360%) induced a sharp decrease in mechanical performance and an undesirable increase in the coefficient of thermal expansion (CTE). The Ni 5 Ce phase was unfavorable to the enhancement of mechanical properties and low thermal expansion behavior. Last but not least, 0.0170 wt% Ce content was advised for Fe-36Ni Invar alloy by considering the balance of strength and thermal expansion behavior. • An approach for Fe-36Ni Invar alloy by Ce treatment was proposed. • The grain size and fraction of annealing twins were sensitive to the Ce content. • Improved mechanical properties were obtained by proper Ce addition. • The proper addition of Ce decreased the coefficient of thermal expansion. • The optimum Ce content of Fe-36Ni Invar alloy was 0.0170%. [ABSTRACT FROM AUTHOR]

The easily cracking behavior of relaxor-PbTiO 3 based ferroelectric crystals limit their application. The average thermal expansion coefficients of PMN-PT and PIN-PMN-PT single crystals are 7.77–8.21 × 10−6 K−1 and 6.59–7.79 × 10−6 K−1 between 20–600 °C. The compression of the crystal by the platinum crucible and the abnormal thermal expansion behavior around phase transition temperature during the cooling process are the main cause of crystal cracking. [Display omitted] • The average thermal expansion coefficients of PMN-PT and PIN-PMN-PT single crystals are 7.77–8.21 × 10–6 K−1 and 6.59–6.79 × 10–6 K−1 between 20–600 °C. • The compression of the crystal by the platinum crucible and the abnormal thermal expansion behavior around phase transition temperature during the cooling process are the main cause of crystal cracking. Large-size Pb(Mg 1/3 Nb 2/3)O 3 -PbTiO 3 (PMN-PT) and Pb(In 1/2 Nb 1/2)O 3 -Pb(Mg 1/3 Nb 2/3)O 3 -PbTiO 3 (PIN-PMN-PT) single crystals have been successfully produced. Nevertheless, the susceptibility of these crystals to cracking substantially hampers their application. This study investigates the thermal expansion characteristics of PMN-PT and PIN-PMN-PT crystals oriented along the 〈1 0 0〉, 〈1 1 0〉, and 〈1 1 1〉 directions, revealing no significant anisotropy. The average thermal expansion coefficients for the PMN-PT and PIN-PMN-PT crystals range from 7.77 to 8.21 × 10−6 K−1 and from 6.59 to 6.79 × 10−6 K−1, respectively, within the temperature range of 20 to 600 °C. Interestingly, the PMN-PT and PIN-PMN-PT crystals demonstrate unusual thermal expansion behavior around the phase transition temperature. The magnitudes of their thermal expansion coefficients are comparable to those of certain commercial crystals but are lower than that of platinum. The main causes inferred for crystal cracking include the pressure exerted by the platinum crucible and the abnormal thermal expansion behavior around the phase transition temperature. [ABSTRACT FROM AUTHOR]