Fabrication of toughened B4C composites with high electrical conductivity using MAX phase as a novel sintering aid

MAX phase Ti₃AlC₂ was chosen as a novel sintering aid to prepare electrically conductive B₄C composites with high strength and toughness. Dense B₄C composites can be obtained at a hot-pressing temperature as low as 1850 °C with 15 vol% Ti₃AlC₂. The enhanced sinterability was mainly ascribed to the in situ reactions between B₄C and Ti₃AlC₂ as well as the liquid phase decomposed from Ti₃AlC₂. Both the Vickers hardness and fracture toughness increase with increasing Ti₃AlC₂ amount, and high hardness and toughness values of 28.5 GPa and 7.02 MPa m^−1/2 respectively were achieved for B₄C composites sintered with 20 vol% Ti₃AlC₂ at 1900 °C. Crack deflection by homogenously distributed TiB₂ particles was identified as the main toughening mechanism. Besides, B₄C composites sintered with Ti₃AlC₂ show significantly improved electrical conductivity due to the percolation of highly conductive TiB₂ phase, which could enhance the machinability of B₄C composites largely by allowing electrical discharge machining.     

Tuning the electronic and thermal transport behaviors of metal-dispersed Ti2O3 composites derived by metal–insulator transition

Thermal management requires an understanding of the relations among the thermal energy transfer, electronic properties, and structures of thermoconductive materials. Here, we enhanced the metal–insulator transition (MIT)-induced effect on the thermal conductivities of microstructure-controlled Ti₂O₃ composites containing W as a thermal conductive filler at approximately 450 K. To change the electronic and thermal transport properties, we varied the particle radii of the conductive phases in the raw material. The change in the calculated electronic thermal conductivity relative to the electrical conductivity of the W_x(Ti₂O₃)_1?x composite was enhanced by compounding the material. When x was reduced from 50 vol% to 20 vol% and the W particle diameter was reduced from 150 μm to 5 μm, the variation in the estimated electronic thermal conductivity of the W_x(Ti₂O₃)_1?x composite was increased by a factor of 2.01. The total thermal conductivity was also changed by the MIT. At x = 50 vol% and a W particle diameter of 5 μm, the maximum thermal conductivity change was 6.34 times larger than that of pure Ti₂O₃. The detailed relation between the MIT-induced changes in thermal transport and the microstructure were elucidated in classical effective medium approximations.     

Densification,microstructure, and thermoelectric properties of AZO/SrTiO3 composites

Al-doped ZnO (AZO) has emerged as a potential high-temperature thermoelectric material with an appropriate Seebeck coefficient and high thermal stability, and hence is considered as a promising material for power generation applications. Herein, we report the fabrication of AZO/SrTiO₃ composites with improved thermoelectric performance. The densification, microstructure, and thermoelectric properties of the AZO/SrTiO₃ composites were investigated. The significant increase in the relative density of AZO from 89.1 to 98.0% after the addition of SrTiO₃ indicates that SrTiO₃ promoted the densification of the composites. Furthermore, the electrical conductivity of AZO increased after the addition of SrTiO₃, which can mainly be attributed to its enhanced relative density. The AZO/SrTiO₃ composite with 2.0 wt% SrTiO₃ showed the highest power factor at 1000 K because of its highest electrical conductivity. In addition, the composite showed the highest ZT value, which was 1.8 times higher than that of pure AZO.     

Improved mechanical properties and toughening mechanism of mullite ceramics reinforced by introducing Ti3AlC2 particles

Ti₃AlC₂, as a toughening phase, was introduced into mullite ceramics for the first time by the pressureless sintering process aiming at improving the mechanical properties. Significant enhancement in density and mechanical performance of mullite ceramics was achieved through the introduction of Ti₃AlC₂ particles. The density of as-prepared mullite–Ti₃AlC₂ composites was increased by 23% (from 2.86 g/cm³ to 3.51 g/cm³) with Ti₃AlC₂ increasing from 0 wt% to 20 wt%. The formation of the liquid phase and decomposed particles from Ti₃AlC₂ are supposed to be responsible for the densification of mullite–Ti₃AlC₂ composites. The optimal mechanical properties were obtained in the mullite–Ti₃AlC₂ composites with 15 wt% Ti₃AlC₂. The bending strength, fracture toughness as well as Vickers hardness were reached 214.36 MPa, 4.84 MPa·m^1/2, and 9.21 GPa, which are 40%, 74%, and 113% higher than pure mullite ceramics, respectively. The improved mechanical performance was mainly attributed to the synergetic action of crack deflection, crack branching and bridging, and strengthened grain boundary.     

Synthesis of low-oxygen Ti3AlC2 powders by hydrogenation–dehydrogenation and deoxidation from titanium scraps

The MAX phase is a material with excellent electrical and thermal conductivity and thermal shock and oxidation resistance owing to its metallike bonding properties. The impurities in the Ti₃AlC₂ MAX phase must be controlled because the oxides and TiC derived from the synthesis process remain in MXene and markedly affect the electrical conductivity and chemical stability. This study investigated whether the Ti₃AlC₂ MAX phase can be synthesized from titanium powder prepared from low-cost titanium scrap by hydrogenation–dehydrogenation (HDH) and deoxidation in the solid-state (DOSS) processes. Almost single-phase Ti₃AlC₂ MAX phase was obtained by synthesis at 1450°C for 5 h. The oxygen concentrations of the HDH-MAX and DOSS-MAX powders (25–45 μm) were 7215 and 3875 ppm, respectively. Oxygen reduction of titanium powder through DOSS can help improve the purity of Ti₃AlC₂ MAX phase by minimizing the imbalance in the stoichiometric ratio during synthesis. The HDH-MAX and DOSS-MAX powders prepared from titanium scrap displayed a higher Ti₃AlC₂ phase fraction and lower oxygen concentration than those of commercial Ti₃AlC₂ MAX phase powders. This cost reduction and purity improvement will increase the accessibility of the Ti₃AlC₂ MAX phase, supporting further research into its applications.     

One-pot fabrication of Ag–SrTiO3 nanocomposite and its enhanced thermoelectric properties

Ag–SrTiO₃ ceramic nanoparticles were fabricated by doping SrTiO₃ with various contents (0.5, 1, 3, and 5%, in mass ratio) of Ag. Composite samples were prepared through a one-pot solvothermal method and sintering process. The temperature-dependent thermoelectric properties of these sample were measured from 300 K to 500 K. The maximum power factor (843.3 μ·W/m·K²) at 500 K, which is ∼3.96 times higher than that of the pristine SrTiO₃ ceramics, was obtained for the Ag–SrTiO₃ composite sample with 1% of Ag. In addition, the thermal conductivity of the composites decreased due to the phonon scattering effect. The maximum thermoelectric figure of merit (ZT), i.e., ∼0.09, which was achieved with 1% of Ag at 500 K, yielded an enhanced power factor and a reduced thermal conductivity. This ZT value was ∼4.27 times larger than that of pristine SrTiO₃ at the same temperature.     

Influence of Ti3AlC2 content and load on the tribological behaviors of Ti3AlC2p/Al composites

In this study, Ti₃AlC₂ particles doped aluminum matrix composites were prepared by ultrasonic agitation casting method. Microstructure, mechanical properties, and tribological properties of pure aluminum and Ti₃AlC_2p/Al composites were characterized. Influence of different loads (10, 20, 30, and 40 N) and Ti₃AlC₂ contents (1.0, 2.0, 3.0, and 4.0 wt%) on the tribological behaviors of the composites were studied. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Energy dispersion spectroscopy (EDS), and 3D laser confocal were used to assist the analysis. The results indicated that fine and uniformly microstructure and the optimum comprehensive mechanical properties were exhibited on 2.0 wt%-Ti₃AlC_2p/Al composites. The abrasive grooves were widened and deepened with an increase in the load. The abrasion performance of composites improved distinctly with the addition of the Ti₃AlC₂ particles, which changed the wear mechanism from adhesive wear to abrasive wear. The 30 N load and the composites of 2.0 wt% Ti₃AlC₂ revealed the optimum tribological properties. The improvement of the tribological behavior of composites was attributed to the refinement of microstructure, the improvement mechanical properties and the three dimensional layered Ti₃AlC₂ phases with self-lubricating properties.     

Effect of Al atomic layer on the wetting behavior,interface structure and electrical contact properties of silver reinforced by Ti3AlC2 ceramic

Ti₃AlC₂ ceramic exhibits potential in Ag-based composite electrical contact materials, but its interface characteristic with Ag matrix remains unexplored. In this work, sessile drop experiment is carried out to investigate the high-temperature wetting behavior of molten Ag with Ti₃AlC₂. Stable Ti₃AlC₂ is hardly wetted by molten Ag below 1000 °C(contact angle of 148.5°), but the wettability of Ag/Ti₃AlC₂ improves with the increasing temperature(final 14° at ～1130 °C). In contrast, the Ti₃C_2, a MXene with Al layer removed from its parent Ti₃AlC₂, exhibits inferior wettability with Ag(final 56.5° at ～1130 °C). Wetting mechanism of Ag/Ti₃AlC₂ is proposed on the basis of the interfacial structure and chemical composition. Increasing temperature accelerates dissociation of Ti₃AlC₂, and outward-escaping Al reacts with Ag to form interface layer with a composition of Ag_4.86Ti_8.66AlC_7.59, Ag also diffuses along Ti₃AlC₂ grain boundaries and forms gradient reactive products(Ag–Ti–Al–C), which promotes their wettability. Finally comprehensive properties of Ag/Ti₃AlC₂ and Ag/Ti₃C₂ are compared. Al–Ag interdiffusion slightly decreases the electrical conductivity of Ag/Ti₃AlC₂ bulk material, but strengthen the interface bonding of composite and promote the viscosity of the molten pool, leading to the superior mechanical and anti-arc erosion properties. Absence of Al–Ag interdiffusion does remarkably improve the electrical conductivity of Ag/Ti₃C₂ bulk materials, but lack of Al layer damages the mechanical core and wettability with Ag, resulting in a drastic decrease of anti-arco erosion property.     

Filtering low-energy carriers to enhance thermoelectric performance of Cd-doped SnSe via incorporation of MXene sheets

SnSe-based materials have attracted widespread attention in thermoelectrics due to their outstanding thermoelectric performance. However, the pristine and unmodified polycrystalline SnSe reveals poor electrical properties. Doping and constructing nanostructured composite architectures to produce energy filtering effect proved to be an effective method to strengthen thermoelectric performance. In this study, Ti₃C₂/Sn_0.98Cd_0.02Se composites are successfully fabricated by the solvothermal method combined with the electrostatic self-assembly method and spark plasma sintering. The phase interface introduced by incorporating Ti₃C₂ into Sn_0.98Cd_0.02Se can effectively filter low-energy carriers due to its generation of energy barriers, thereby the Seebeck coefficient of x wt% Ti₃C₂/Sn_0.98Cd_0.02Se x = (0.05, 0.5, 1) samples is better than that of the pristine Sn_0.98Cd_0.02Se over the whole temperature range. Meanwhile, high conductivity was also obtained in 1 wt% Ti₃C₂/Sn_0.98Cd_0.02Se sample so that the high power factor of 3.31 μWcm⁻¹K⁻² was acquired at 773 K. Ultimately, a peak ZT value of 0.41 was obtained at 773 K, compared with pristine Sn_0.98Cd_0.02Se, and the thermoelectric performance improved by 24%. This study offers an available approach to efficiently enhance the thermoelectric properties of polycrystalline SnSe-based materials.     

Fabrication of graphene oxide-Ti3AlC2 synergistically reinforced copper matrix composites with enhanced tribological performance

Ceramic particles reinforced copper (Cu) matrix composites with good electrical conductivities, superior mechanical and tribological properties show great prospect in electrical contacts, thermal management and sliding bearing materials. A novel Cu matrix composite with low coefficient of friction (COF) and high wear resistance is rationally designed and prepared by hot-press sintering the core-shell structured Cu/graphene oxide (GO)/Cu composite powders and Cu decorated Ti₃AlC₂ particles to achieve homogenous dispersion of GO in the Cu matrix and good interfacial bonding of Cu matrix and GO and Ti₃AlC_2. Its tribological performance and corresponding anti-wear alongside with friction reduction mechanisms at room temperature are systematically investigated. The GO-Ti₃AlC₂ synergistically enhanced Cu matrix composite exhibits lower COF and wear rate than those composites reinforced with GO or Ti₃AlC₂ alone_, for GO and Ti₃AlC₂ synergistically bear the load and form continuous, compact and lubricating tribo-layer on the worn surface.     

Electrically conductive and corrosion resistant MAX phases with superior electromagnetic wave shielding performance

MAX phases have emerged as promising corrosion-resistant electromagnetic interference (EMI) shielding materials. Herein, four MAX phases: Ti₃SiC₂, Ti₃AlC₂, V_0.5Cr_1.5AlC, and Nb₄AlC₃, were synthesized via solid–liquid reactions. The electrical conductivities of Ti₃SiC₂, Ti₃AlC₂, V_0.5Cr_1.5AlC, and Nb₄AlC₃ are 14.7 × 10³, 15.5 × 10³, 5.1 × 10³, 8.0 × 10³ S/cm, respectively, and the corresponding average EMI shielding effectiveness values in the frequency of 18–26.5 GHz are 53.9, 69.2, 19.4, and 29.0 dB, respectively. Most importantly, these MAX phases are highly corrosion resistant under acidic conditions. Despite the exposure to the acidic environment and a slight decrease in the electrical conductivity, the corroded MAX phases exhibited excellent EMI shielding properties compared to the pristine MAX phases. Additional analysis showed that reflection was the primary EMI blocking mechanism. The study offers a guide for designing MAX phase ceramics that exhibit high EMI shielding performance in corrosive environments.     

Effect of thermal stability of Mn+1AXn phases on microstructure and mechanical properties of Mn+1AXn/ZA27 composites

Special layered structure endows ternary M_n+1AX_n phase ceramics with good electrical and thermal conductivity, excellent abrasive resistance, and perfect thermal shock resistance. In this work, three kinds of M_n+1AX_n phase ceramics (Ti₃SiC₂, Ti₃AlC₂, and Ti₂SnC) were chosen to reinforce the ZA27 alloys, respectively. By employing “two-step sintering” technology which is pressureless sintered at 870°C for 1 h firstly and then hot pressed at 500°C for 1 h, M_n+1AX_n/ZA27 composites were successfully fabricated. The effects of thermal stability of the above M_n+1AX_n on microstructure, mechanical properties, and friction performance of the three M_n+1AX_n/ZA27 composites were investigated. The different reaction degrees between the three M_n+1AX_n reinforcements and the ZA27 matrix were ascribed to the differences of chemical bond energy. The results demonstrated that at the sintering temperature of 870°C, Ti₂SnC was completely reacted in Ti₂SnC/ZA27 composite, and Ti₃AlC₂ partially reacted in ZA27 matrix, while no reaction happened between Ti₃SiC₂ and ZA27 matrix. Hence, the order of thermal stability for the three M_n+1AX_n phases in ZA27 matrix is Ti₃SiC₂ > Ti₃AlC₂ > Ti₂SnC. Besides, Ti₃AlC₂/ZA27 composites possess the best mechanical properties and wear resistance, which was attributed to interfacial reaction improved the boding between matrix and reinforcement.     

Enhancing thermoelectric properties of p-type (Bi,Sb)2Te3 via porous structures

Bismuth telluride is a widely used commercial thermoelectric material with excellent thermoelectric performances near room temperature. Reducing thermal conductivity is one of the most effective ways to improve performances of thermoelectric materials. In this study, the thermal conductivity of the material was reduced by fabricating porous structures. Highly dense NaCl-(Bi,Sb)₂Te₃ composites were fabricated by a high-pressure technology. The NaCl phase was then removed from the composites by ultrasonic washing to produce porous structures. The produced (Bi,Sb)₂Te₃ porous materials possessed excellent thermoelectric properties. The porosity and pore size of the (Bi,Sb)₂Te₃ porous materials increased with the increasing NaCl content, decreasing the thermal conductivity significantly. An ultra-low lattice thermal conductivity of 0.21 Wm^?1K^?1 at 493 K was achieved when the porosity was 39%, almost the lowest lattice thermal conductivity reported for (Bi,Sb)₂Te₃ bulk materials. The figure of merit ZT value was enhanced to 1.05 at 493 K when the porosity was 25%. Compared with the most compacted samples (ZT = 0.79 and porosity of 10%) prepared under the same conditions, the ZT value of the porous samples increased by 33%. This study indicated that porous thermoelectric materials can be prepared simply, quickly and efficiently by high-pressure/ultrasonication washing to improve thermoelectric performances, which has evident reference values for preparing other thermoelectric pore materials with enhancing behaviors.     

Microstructure and High‐temperature Oxidation Behavior of Ti3AlC2/W Composites

Using spark plasma sintering, Ti₃AlC₂/W composites were prepared at 1300°C. They contained “core‐shell” microstructures in which a Ti_xW_1?x “shell” surrounded a W “core”, in a Ti₃AlC₂ matrix. The composite hardness increased with W addition, and the hardening effect is likely achieved by the Ti_xW_1?x interfacial layer providing strong bonding between Ti₃AlC₂ and W, and by the presence of hard W. Microstructural development during high‐temperature oxidation of Ti₃AlC₂/W composites involves α‐Al₂O₃ and rutile (TiO₂) formation ≥1000°C and Al₂TiO₅ formation at ~1400°C while tungsten oxides appear to have volatilized above 800°C. Likely due to exaggerated, secondary grain growth of TiO₂‐doped alumina and the effect of W addition, fine (<1 μm) Al₂O₃ grains formed dense, anisomorphic laths on Ti₃AlC₂/5 wt%W surfaces ≥1200°C and coarsened to large (>5 μm), dense, TiO₂‐doped Al₂O₃ clusters on Ti₃AlC₂/10 wt%W surfaces ≥1400°C. W potentially affects the oxidation behavior of Ti₃AlC₂/W composites beneficially by causing formation of Ti_xW_1?x thus altering the defect structure of Ti₃AlC₂, resulting in Al having a higher activity and by changing the scale morphology by forming dense Al₂O₃ laths in a thinner oxide coating, and detrimentally through release of volatile tungsten oxides generating cavities in the oxide scale. For Ti₃AlC₂/5 wt%W oxidation, the former beneficial effects appear to dominate over the latter detrimental effect.     

Nb doping in Ti3AlC2: Effects on phase stability,high-temperature compressive properties,and oxidation resistance

Nb-based ‘312’ MAX phase has not been recognized so far, raising a hypothesis that Nb doping would destabilize the isostructural Ti₃AlC₂. Here we report that (Ti_1−xNb_x)₃AlC₂ could persist with a doping limitation up to x = 0.15. As demonstrated by HAADF-STEM analysis, Nb dopants homogeneously distribute among polycrystalline grains at the microscale and randomly occupy the Ti sites at the atomic level. Beyond the limitation, Nb-doped ‘312’ phase Ti₃AlC₂ decomposes into (Ti,Nb)C, Nb-doped ‘211’ phase Ti₂AlC, and Nb-based ‘413’ phase. Compared to pristine Ti₃AlC₂, the compressive strength of (Ti_0.9Nb_0.1)₃AlC₂ at 1200 °C increases by 130%, whereas doping at this level impairs the oxidation resistance. Improving high-temperature strength without deteriorating oxidation resistance can be achieved by 5% Nb doping.     

On the potential of polyetheretherketone matrix composites reinforced with ternary nanolaminates for tribological and biomedical applications

We report the synthesis and characterization of PEEK-MAX (Ti₃SiC₂, Ti₃AlC₂, and Cr₂AlC), and PEEK-MoAlB composites by hot-pressing. Detailed microstructure analysis by scanning electron microscopy showed that Ti₃SiC₂ particles are well dispersed in the PEEK matrix after the addition of 5 vol% Ti₃SiC₂ but at higher concentration (≥10 vol%), the Ti₃SiC₂ particles segregated at the phase boundaries and formed interpenetrating micro-networks. PEEK-Ti₃AlC₂ and PEEK-MoAlB composites also showed similar structuring at the microstructural level. PEEK-Cr₂AlC composites showed a different behavior where Cr₂AlC particles were well dispersed in the PEEK matrix. All the three PEEK-MAX composites have lower hardness than PEEK-MoAlB composites as MoAlB particulates are appreciably harder than MAX phases but were harder than PEEK. Due to heterogenous nucleation, the addition of MAX phases or MoAlB reduced the crystallization temperature (T_c) by a few ^oC. The formation of imperfect crystals also resulted in the lowering of melting point (T_m) of these composites. PEEK reinforced with 10 vol% Ti₃SiC₂, Ti₃AlC₂ and MoAlB showed plastic failure, and had higher strength than PEEK. Comparatively, PEEK reinforced with 10 vol% Cr₂AlC did not show any enhancement. All the PEEK-MAX and PEEK-MoAlB composites showed triboactive behavior and enhanced wear resistance.     

Enhanced dielectric and mechanical properties of CaCu3Ti4O12/Ti3C2Tx MXene/silicone rubber ternary composites

Dielectric polymer composites with conducting fillers would have great potential for diverse applications if their severe leakage loss could be addressed. In this regard, ternary composites using both ceramic and conducting materials as fillers might be an enabler for high dielectric constant and low dielectric loss. Herein, ternary composites with both Ti₃C₂T_x MXene conducting nanosheets and CaCu₃Ti₄O₁₂ (CCTO) dielectric particles embedded in silicone rubber were studied. It was found that a ternary composite with 1.2 wt% (0.40 vol%) Ti₃C₂T_x MXene and 12 wt% (2.58 vol%) CCTO could provide an overall superior performance that include a high dielectric constant of 8.8, low dielectric loss of less than 0.0015, good thermal stability up to 450 °C, and excellent mechanical properties with tensile strength of 569 kPa, elastic module of 523 kPa and elongation at break of 333%. The outstanding performance is attributed to the improved uniform dispersion and good interfacial compatibility of mixed fillers in the polymer matrix, suggesting ternary composites might be a better option over their binary counterparts in preparing high performance dielectric composites.     

Microstructure and thermoelectric properties of La0.1Dy0.1SrxTiO3 ceramics

La_0.1Dy_0.1Sr_xTiO₃ (x=0.80, 0.78, 0.75, 0.70) powders were synthesized via a sol-gel method, followed by sintering at 1550 °C in a reducing atmosphere of 5 vol% hydrogen in nitrogen. The microstructure and thermoelectric properties of the Sr-deficient La and Dy co-doped SrTiO₃ were investigated. The result of XRD revealed that La_0.1Dy_0.1Sr_xTiO₃ consisted of SrTiO₃ with a cubic crystal structure as the main phase and of a small amount of Dy₂Ti₂O₇ as the second phase. All the Sr-deficient samples exhibited a step-like microstructure. As the nominal Sr deficient content increased, the electrical conductivity of the Sr-deficient La_0.1Dy_0.1Sr_xTiO₃ ceramics enhanced due to the increasing Sr and oxygen vacancies, the absolute value of the Seebeck coefficient increased a little, and the thermal conductivity decreased to ~3.0 W m⁻¹ K⁻¹, leading to a high ZT value of 0.19 for La_0.1Dy_0.1Sr_0.75TiO₃ at 500 °C.     

Molten salt synthesis and formation mechanism of Ti3AlC2: A new path from Ti2AlC to Ti3AlC2

Fine, pure Ti₃AlC₂ powder is prepared in a very mild condition via Ti₃Al alloy and carbon black with the assistance of molten salts. X-ray diffraction, scanning electron microscopy, TG-DSC, and transmission electron microscopy (TEM) characterizations show that the high purity, nanosized Ti₃AlC₂ can be obtained at 900°C with the 1:1 salt-to-material ratio. The formation mechanism of Ti₃AlC₂ through this strategy of alloy raw material is fully studied under further TEM investigations, showing that the reaction process can basically be described as Ti₃Al and C → TiAl and TiC → Ti₂AlC and TiC → ψ and TiC → Ti₅Al₂C₃ and TiC → Ti₃AlC₂, where the key ψ, a modulated Ti₂AlC structure, is determined for the first time containing alternate-displacement Al layers along (0 0 0 2) of Ti₂AlC phase with a distinct selected area electron diffraction pattern. Such alternant displacement is considered a precondition of forming Ti₅Al₂C₃ through topotactic transition, followed by Ti₅Al₂C₃ converting into Ti₃AlC₂ by the diffusion of Ti, C atoms in the outside TiC. Several parallel orientations can be observed through the phase transition process: Ti₂AlC (0 0 0 2)//ψ (0 0 0 1), ψ (0 0 0 1)//Ti₅Al₂C₃ (0 0 0 3), Ti₅Al₂C₃ (0 0 0 3)//Ti₃AlC₂ (0 0 0 2). Such parallel orientations among these phases apply an ideal condition for the topotactic reaction. The distinct path of the phase transition brings a significant change of heat effect compared with the traditional method, leading to a fast reaction rate and a mild reaction condition.     

A novel high-entropy perovskite ceramics Sr0.9La0.1(Zr0.25Sn0.25Ti0.25Hf0.25)O3 with low thermal conductivity and high Seebeck coefficient

In this work, a novel high-entropy n-type thermoelectric material Sr_0.9La_0.1(Zr_0.25Sn_0.25Ti_0.25Hf_0.25)O₃ with pure perovskite phase was prepared using a conventional solid state processing route. The results of TEM and XPS show that various types of crystal defects and lattice distortions, such as oxygen vacancies, edge dislocations, in-phase rotations of octahedron and antiparallel cation displacements coexist in this high-entropy ceramic. At 873 K, the high-entropy ceramics showed both a low thermal conductivity (1.89 W/m/K) and a high Seebeck coefficient (393 μV/K). This work highlights a way to obtain high-performance perovskite-type oxide thermoelectric materials through high-entropy composition design.