Tungsten Bronze Structure Research Articles

Low-Temperature Synthesis of Tungsten Silicates with Pyrochlore and Tungsten Bronze Structure

Low-Temperature Synthesis of Tungsten Silicates with Pyrochlore and Tungsten Bronze Structure

Enhanced energy storage performance of tungsten bronze structured BaNb2O6-modified (Bi0.5Na0.5)TiO3 ceramics

The rapid development of the electronic devices and increasing attention to environmental problems have put forward a huge demand for high-performance lead-free dielectric energy storage ceramics. In this work, tungsten bronze structured BaNb2O6 (BN) modified perovskite structured (Bi0.5Na0.5)TiO3 (BNT) ceramics, BNT-xBN (0 <x< 0.15), were prepared to optimize the energy storage performance of BNT. The results show that the lattice distortion and dielectric relaxation behavior of BNT ceramic can be induced by BN addition. Meanwhile, the introduction of tungsten bronze structured BN results in the grain refinement and the increasing of resistivity, thereby significantly enhancing the electrical breakdown strength (Eb). Accordingly, the BNT-0.1BN ceramic displays good energy storage performance with high recoverable energy density (Wrec ∼ 3.41 J/cm3) at an great Eb of 358 kV/cm, accompanied by the wide temperature stability at 30–150 °C (Wrec varies within ±12.8 %, efficiency (η) varies within ±6.7 %). The enhanced energy storage performance demonstrates that introducing tungsten bronze structure is a feasible method to prepare high-performance perovskite energy storage ceramics.

Ferroelectric tungsten bronze-based ceramics with high-energy storage performance via weakly coupled relaxor design and grain boundary optimization

A multiscale regulation strategy has been demonstrated for synthetic energy storage enhancement in a tetragonal tungsten bronze structure ferroelectric. Grain refining and second-phase precipitation (perovskite phase) are introduced in the BaSrTiNb2-xTaxO9 ceramics by regulating the composition and sintering process. Disordered polarization and distribution, chemical inhomogeneity, and insulating boundary layers are achieved to provide the fundamental structural origin of the relaxation characteristic, high breakdown strength, and superior energy storage performance. Thus, an ultrahigh energy storage density of 12.2 J cm−3 with an low energy consumption was achieved at an electric field of 950 kV cm−1. This is the highest known energy storage performance in tetragonal tungsten bronze-based ferroelectric. Notably, this ceramic shows remarkable stability over frequency, temperature, and cycling electric fields. This work brings new material candidates and structure design for developing of energy storage capacitors apart from the predominant perovskite ferroelectric ceramics.

Enhancing structural strength and microwave dielectric properties of the Ba4(Sm1-xCex)9.33Ti18O54 ceramics

Herein, microwave dielectric ceramics of the Ba4Sm9.33Ti18O54 ceramics are substituted at A sites by partially replacing Sm at A1 sites with Ce, and the effects of ionic substitution at A sites on ceramic crystal structure and microwave dielectric properties are investigated. The Ba4(Sm1-xCex)9.33Ti18O54 (BSCT) ceramics prepared through the solid phase method has a typical tungsten–bronze structure, and its lattice spacing increases gradually with the increase in Ce content x. This increase is reflected in the increase in the cell volume and growth of ceramic grains. However, the excess Ce after Ce content exceeds 0.25 leads to the growth of ceramic grains and increase in porosity between grains, which in turn increases the dielectric loss of the ceramic. Under optimal sintering conditions, the ceramic crystal has a maximum atomic packing density of x = 0.25, which corresponds to its most stable structural properties, and the highest Q × f value of 9013 GHz. Raman spectroscopy results indicate that in titanium oxygen octahedrons, an increase in Ce substitution can effectively weaken the bending and tensile vibration intensities of titanium oxygen bonds, further enhancing structural strength.

Photocatalytic water splitting over K3Li2Ta5O15 with a C-site-filled tungsten bronze structure and influence of metal cations at C-site on photocatalytic properties

Abstract K3Li2Ta5O15 is found as a novel photocatalyst for overall water splitting under UV light irradiation. K3Li2Ta5O15 possesses a characteristic crystal structure with Li+ ions-filled C-sites in (A1)4(A2)2C4M10O30 as the general formula of a tungsten bronze type metal oxide. Most of the reported photocatalysts with a tungsten bronze structure possess empty C-sites. K6Ta10.8O30 also possesses a C-site-filled tungsten bronze structure where C-sites are partially filled by Ta5+ ions. In diffuse reflectance spectra, K6Ta10.8O30 has an absorption edge at longer wavelength than K3Li2Ta5O15. This narrower band gap of K6Ta10.8O30 than K3Li2Ta5O15 is considered to be due to the presence of Ta5+ ions at C-sites in K6Ta10.8O30. Ta5+ ions located at 9-fold coordination C-sites with totally different surrounding environment from the 6-fold coordination M-sites will form the conduction band minimum at lower potential than those located at 6-fold coordination M-sites. The optimized K3Li2Ta5O15 shows almost the same water splitting activity with the optimized K6Ta10.8O30. Thus, it is found that the conduction band formed by Ta5+ ions at C-sites is also effective for photocatalytic reaction, being similar to that formed by Ta5+ ions at M-sites.

Evolution of Ferroelectricity in Sr0.6Ba0.4Nb2O6-BaTiO3 Solid Solution with a Strong Electrocaloric Effect.

In conventional knowledge, ferroelectric solid solutions were formed between members belonging to the same crystal structure family. Since both tungsten bronze and perovskite structures are constructed by connecting the corner-sharing oxygen octahedra, it offers a possibility for formatting an unusual solid solution between these two families. Herein, (1 - x)Sr0.6Ba0.4Nb2O6-xBaTiO3, (1 - x)SBN-xBT, solid solutions were synthesized and the solution mechanism was resolved from a structure viewpoint. With increasing BT content, the solid solution persists of tetragonal tungsten bronze structure, but the lattice parameter a (= b) decreases whereas c increases, resulting in the significant reduction of grains anisotropy. The ferroelectric-relaxor phase transition temperature shows a monotonic increase as x increases. However, the ferroelectricity evolution is not monotonous as a function of BT content because of the competitive effects of Ba and Ti on the property. As a result, the x = 0.10 ceramic shows the strongest ferroelectricity and a remarkable electrocaloric effect of 1.4 K near room temperature. This work challenges the traditional view of solid solution formation and provides an alternative way to modulate the structure and properties of ferroelectrics.

Crystal Structure, Infrared Reflection Spectrum, and Improved Microwave Dielectric Characteristics of Ba4Sm28/3Ti18O54 Ceramics via One-Step Reaction Sintering.

High-k Ba4Sm28/3Ti18O54 ceramics with improved microwave dielectric characteristics were successfully fabricated using the one-step reaction sintering (RS) route. The sintering characteristics, microstructure, crystal structure, infrared reflection spectrum, and microwave dielectric characteristics of Ba4Sm28/3Ti18O54 ceramics prepared by the RS route were systematically investigated. Samples prepared by the RS route exhibited single-phase orthorhombic tungsten-bronze structure and dense microstructure at optimum sintering temperature. Compared with the conventional solid-state (CS) process, the Ba4Sm28/3Ti18O54 ceramics fabricated by the RS route presented a smaller temperature coefficient (TCF), a higher quality factor (Q × f), and a higher permittivity (εr). The improved microwave dielectric characteristics were highly dependent on the theoretical permittivity, atomic packing fraction, suppression of Ti3+, and Ti-site bond valence. Excellent combined microwave dielectric characteristics (TCF = -7.9 ppm/°C, Q × f = 9519 GHz, εr = 80.26) were achieved for Ba4Sm28/3Ti18O54 ceramics prepared by RS route sintered at 1400 °C, suggesting the RS route was a straightforward, economical and effective route to prepare high-performance Ba4Sm28/3Ti18O54 ceramics with promising application potential.

Outstanding energy density and charge-discharge performances in Sr2KNb5O15-based tungsten bronze ceramics for dielectric capacitor applications

Relaxor ferroelectric ceramics are extremely encouraging materials for energy storage capacitor applications in pulse equipment. As the second largest ferroelectric ceramic system, tungsten bronze structure relaxor ferroelectric ceramics have emerged as a significant contender and garnered significant attention in the pulse capacitor research field. In this work, an Sb-modified Sr2KNb5O15-based tungsten bronze relaxor ferroelectric ceramic system is designed to explore its energy storage potential. XRD refinement reveals the declines in the oxygen octahedra tilting and distortion after the introduction of Sb, which significantly augments the relaxation behavior. Additionally, refined grain size and reduced oxygen vacancy concentration are observed, greatly improving the breakdown strength. Consequently, a superior energy storage density (∼4.57 J/cm3) accompanied by wonderful energy storage efficiency (∼89.3 %) is received at 540 kV/cm, with wide frequency stability and great thermal stability. Moreover, amazing discharging performances are also achieved with rapid discharge speed (τ0.9 < 70 ns), towering discharge current density (815.2 A/cm2) and surprising power density (130.4 MW/cm3). All these performances indicate that the designed Sr2KNb5O15-based tungsten bronze relaxor ferroelectric ceramic can be one encouraging option in the dielectric energy storage field.

Photocatalytic water splitting over K6M10.8O30 (M = Ta, Nb) with a partially filled tetragonal tungsten bronze structure

Abstract K6M10.8O30 (M = Ta, Nb) with partially filled C sites in a tetragonal tungsten bronze structure represented as the general formula (A1)4(A2)2C4M10O30 shows photocatalytic activity for water splitting under UV light irradiation upon loading with suitable cocatalysts. An apparent quantum yield of the optimized NiO(0.2 wt%)-loaded K6Ta10.8O30 for water splitting is 13% at 248 nm.

Enhancement of dielectric performance in tungsten bronze ceramics by substituting 25 % of Gd into Sr2SmTi2Nb3O15 ceramic

This study investigates the synthesis and systematic examination of tungsten bronze ceramics Sr2GdxSm1-xTi2Nb3O15 (SGSTN, x = 0, 0.25, 0.5, 0.75) using the solid-state reaction method. X-ray diffraction revealed tetragonal tungsten bronze structures with space group P4/mbm for x = 0.25, 0.5, and 0.75, and P4bm for x = 0. Scanning electron microscopy showed high densification and uniform grain dispersion, with grain sizes ranging from 6.2 to 10.8 μm depending on the Gd content. Impedance spectroscopy demonstrated that the dielectric properties were influenced by the addition of Gd3+, with a dielectric constant of 2549.97 at 400 °C and 1 kHz for x = 0.25. Impedance analysis suggested a negative temperature coefficient of resistance (NTCR), and Cole-Cole plots showed single semicircular arcs. Activation energy increased with decreasing (A1)-site ion size, indicating that oxygen vacancies were responsible for the relaxation phenomena. Complex modulus analysis confirmed the presence of non-Debye relaxations in the material.

Lithiation kinetics and performance of Nb18Mo16O93 anode materials based on tetragonal tungsten-bronze structures

In lithium-ion batteries (LIBs) anode materials, Nb2O5 has a higher specific capacity and working potential than graphite, but its low conductivity and the problem of asynchronous phase transition in the reaction limit the specific capacity as well as the cycling performance of the material. In this study, Nb18Mo16O93 LIBs anode materials with tetragonal tungsten bronze (TTB) structure were successfully synthesized by combining ball milling and calcination method, using MoO3 and Nb2O5 as raw materials. The introduction of Mo atoms has led to the formation of a new material that solves the problem of low electrical conductivity of Nb2O5. Meanwhile, the Nb18Mo16O93 material forms three kinds of channels to promote Li+ transport, namely pentagonal, square channel and triangular, due to its special TTB structure. In addition, the rod-like morphology of the Nb18Mo16O93 material provides a larger contact area between the electrolyte and the electrode material, which improves the adsorption and diffusion efficiency of lithium ions. Nb18Mo16O93 as an anode material maintained a specific capacity of 692 mAh g−1 after 300 cycles at 0.1 A g−1 and 75.5 mAh g−1 after 3000 cycles at a high current of 5 A g−1. The preparation of Nb18Mo16O93 provides a new direction to solve the shortcomings of Nb2O5.

Anti-reduction mechanism of Ba4.2Sm9.2Ti18O54 ceramics by Mg2+/Ta5+ complex ion co-doping

In this work, a novel anti-reduction mechanism was put up by substituting (Mg1/3Ta2/3)4+ complex ion for Ti4+ ion in Ba4.2Sm9.2Ti18-x(Mg1/3Ta2/3)xO54 (0 ≤ x ≤ 0.1) ceramics. The influence of (Mg1/3Ta2/3)4+ complex ion on the sintering behavior, crystal structure, anti-reduction mechanism and microwave dielectric properties of Ba4.2Sm9.2Ti18-x(Mg1/3Ta2/3)xO54 ceramics was investigated. The results indicated that Ba4.2Sm9.2Ti18-x(Mg1/3Ta2/3)xO54 ceramics maintained a typical single-phase tungsten bronze structure. After doping, the ceramic exhibited dense structure and typical columnar grains. Raman spectroscopy and XPS analysis confirmed the reduction of oxygen vacancies and obtained a 7.86 % decrease of Ti3+ ions. Due to the anti-reduction of Ti4+ ions, Ba4.2Sm9.2Ti18-x(Mg1/3Ta2/3)xO54 ceramics possessed an improvement in microwave dielectric properties. In Ba4.2Sm9.2Ti18-x(Mg1/3Ta2/3)xO54 (0 ≤ x ≤ 0.1) ceramics, the Ba4.2Sm9.2Ti17·95(Mg1/3Ta2/3)0.05O54 (x = 0.05) ceramic sintered at 1350 °C for 4 h showed the best integrated microwave dielectric properties with εr = 79.62, Qf = 10,450 GHz and τf = −10.66 ppm/°C.

W7Nb4O31 Nanorods with a Mixed Crystal Structure: A Very Fast‐ and Stable‐Charging Anode Material for Aqueous Lithium‐Ion Batteries

AbstractAqueous lithium‐ion batteries (ALIBs) have attracted extensive interest since the safety problems of traditional lithium‐ion batteries are waived. Although the energy density of ALIBs is improved, their rate capability and power density are still poor due to the slow Li+ diffusivity of the existing anode materials, and their cyclic stability is also poor. Here, W7Nb4O31 nanorods with very fast‐ and stable‐charging capability are explored as a new anode material for ALIBs for the first time. This material owns different tetragonal tungsten bronze (TTB) structures together with 4 × 4 ReO3‐type blocks confined by TTB matrices, allowing abundant pentagonal and quadrangular tunnels for Li+ transport. These large‐sized tunnels combine with the large interlayer spacing (≈3.95 Å) not only lead to extremely fast Li+ diffusivity but also small unit‐cell volume variations (maximum 2.1%) during lithiation/delithiation, thereby enabling the LiMn2O4//W7Nb4O31 full cell to possess excellent rate capability with a 50C versus 1C capacity ratio of 68.3%, ultrahigh power density of 9854 W kg–1, and superior cyclic stability with capacity retention of 89.7/66.7/72.0% at 1C/5C/50C over 1000/10 000/10 000 cycles. This comprehensive study demonstrates that the W7Nb4O31 nanorods are highly promising for fast‐ and stable‐charging ALIBs.

Porous Nb4W7O31 microspheres with a mixed crystal structure for high-performance Li+ storage

Niobium-tungsten oxides with tungsten bronze and confined ReO3 crystal structures are prospective anode candidates for lithium-ion batteries since the multi-electron transfer per niobium/tungsten offers large specific capacities. To combine the merits of the two structures, porous Nb4W7O31 microspheres constructed by nanorods are synthesized based on a facile solvothermal method. This new material contains different tungsten bronze structures and 4 × 4 ReO3-type blocks confined by tungsten bronze matrices, generating plenty of pentagonal and quadrangular tunnels for Li+ storage, as confirmed by spherical-aberration-corrected scanning transmission electron microscopy. Such structural mixing enables three-dimensionally uniform and small lattice expansion/shrinkage during lithiation/delithiation, leading to good structural and cyclic stability (95.2% capacity retention over 1,500 cycles at 10C). The large interlayer spacing (~3.95 Å), coupled with the abundant pentagonal/quadrangular tunnels, results in ultra-high Li+ diffusion coefficients (1.24 × 10-11 cm2 s-1 during lithiation and 1.09 × 10-10 cm2 s-1 during delithiation) and high rate capability (10C vs. 0.1C capacity retention percentage of 47.6%). Nb4W7O31 further exhibits a large reversible capacity (252 mAh g-1 at 0.1C), high first-cycle Coulombic efficiency (88.4% at 0.1C), and safe operating potential (~1.66 V vs. Li/Li+). This comprehensive study demonstrates that the porous Nb4W7O31 microspheres are very promising anode materials for future use in high-performance Li+ storage.

Tailoring Zr-doped tungsten bronze (Sr,Ba,Gd)Nb2O6 relaxor ferroelectric with high electrical insulation interface for dielectric capacitor

Tetragonal tungsten bronze structure (TTB) compounds have attracted tremendous interest for their applications in energy storage, especially as dielectric capacitor mediums. However, constrained by the inverse correlation of polarization and electric breakdown field in relaxor ferroelectrics, there is still a major challenge in improving energy density. To addresse this challenge, a viable strategy of constructing relaxor behavior with robust electrical insulation in TTB-type Sr0.485Ba0.47Gd0.03Nb2-xZrxO6 (SBN-Gd-Zrx) by introducing ZrO2 during the preparation process was proposed. By introducing Zr4+ in the B-site, we have revealed how Zr4+ affects the dielectric and ferroelectric characteristics to explore the intrinsic relaxation. Based on the analysis of Rietveld refinement against synchrotron X-ray powder diffraction and Raman results, the substitution of Gd3+ and Zr4+ for Sr2+ and Nb5+ in Sr0.53Ba0.47Nb2O6 caused a decline in tetragonality and a shrinkage of the unit cell due to the lattice defect of [GdSr]• and [ZrNb]', which mutually compensates effectively alleviate the distortion of BO6 and then favors the balance of polarization and dielectric constant. The accrual of additional ZrO2 at grain boundaries significantly enhances electrical insulation characteristics, as validated by complex impedance spectroscopy. At near room temperature, all Zr-doped SBN-Gd compounds of the series exhibit heightened relaxation and undergo a phase transition from ferroelectric to paraelectric. As a result, in tandem with the synchronous augmentation in breakdown electric field (EB) and saturation polarization (Pm), optimal energy storage characteristic is realized in the SBN-Gd-Zr0.2 sample. It attains a remarkable Wrec of 2.67 J/cm3 and an efficiency ƞ of 91.21 %, showcasing excellent suitability in terms of different frequencies and temperatures, which far exceeds that of Gd-modified SBN ceramics and pure SBN ceramics. These results exemplify an efficacious strategy for designing novel TTB dielectrics by coupling relaxor modulation with electrical insulation, and position them competitively for implementation in dielectric storage capacitors utilized in pulsed power devices.

Improved energy storage performance and thermal stability of hafnium-substituted strontium sodium niobate tungsten bronze ceramics.

Dielectric capacitors are widely used in the field of pulsed power systems owing to their ultra-fast charge and discharge capacity; however, considering the complex environment they face in practical applications, how to further improve their thermal stability is an urgent issue that needs to be solved. Tungsten bronzes have the potential to broaden the temperature stability range owing to their unique structure, but only few studies have focused on them. Herein, lead-free Sr4-x La x Na2Hf x Nb10-x O30 ceramics with a tungsten bronze structure were synthesized, and their energy storage properties were comprehensively characterized. With proper Hf substitution in the B site and rare earth substitution in the A site, significantly enhanced relaxor behavior is induced, leading to a broad plateau of the dielectric curve, slim polarization-electric field loop, high energy storage efficiency and stable capacitive performance over a wide temperature range. In addition, an improved microstructure with fewer defects, decreased average grain size, increased band gap and resistance were obtained, which benefit to the increase in breakdown strength and energy storage density. Finally, improved energy storage performance and thermal stability were achieved for the compounds, with W total = 3.6 J cm-3, W rec = 2.9 J cm-3, η = 80% and stable temperature range = 20-160 °C. Thus, the current system is a promising candidate for application in temperature-stable dielectric capacitors.

Ultrahigh Energy Storage in Tungsten Bronze Dielectric Ceramics Through a Weakly Coupled Relaxor Design.

Dielectric energy-storage capacitors, known for their ultrafast discharge time and high-power density, find widespread applications in high-power pulse devices. However, ceramics featuring a tetragonal tungsten bronze structure (TTBs) have received limited attention due to their lower energy-storage capacity compared to perovskite counterparts. Herein, a TTBs relaxor ferroelectric ceramic based on the Gd0.03 Ba0.47 Sr0.485-1.5 x Smx Nb2 O6 composition, exhibiting an ultrahigh recoverable energy density of 9 J cm-3 and an efficiency of 84% under an electric field of 660kV cm-1 is reported. Notably, the energy storage performance of this ceramic shows remarkable stability against frequency, temperature, and cycling electric field. The introduction of Sm3+ doping is found to create weakly coupled polar nanoregions in the Gd0.03 Ba0.47 Sr0.485 Nb2 O6 ceramic. Structural characterizations reveal that the incommensurability parameter increases with higher Sm3+ content, indicative of a highly disordered A-site structure. Simultaneously, the breakdown strength is also enhanced by raising the conduction activation energy, widening the bandgap, and reducing the electric field-induced strain. This work presents a significant improvement on the energy storage capabilities of TTBs-based capacitors, expanding the material choice for high-power pulse device applications.

Different effect of Li+, Na+, K+ -doping on crystal structure and electrical property of Sr0.6Ba0.4Nb2O6

Ferroelectric Sr0.6Ba0.4Nb2O6 (SBN) shows typical unfilled tetragonal tungsten bronze structure where 1/6 A sites and all C sites are unoccupied. The presence of such structural vacancy provides the possibility to further modulate the crystal structure and electrical properties. In this work, alkali ions (Li+, Na+, K+) doped SBN ceramics have been fabricated via solid-solution reaction method. In general, each doping promotes the crystal structure evolves from unfilled toward filled tungsten bronze. However, the different doping ion radius causes the differences in occupying initial structural vacancies, resulting in significantly different electrical properties, Li+ doping enhances relaxor characteristic whereas Na+ and K+ doping lead to normal ferroelectric behavior, accompanying an increase in Curie temperature (TC) from 36 °C of SBN to 40, 212, 148 °C of Li+, Na+ and K+ doping, respectively. Benefiting from improved relaxor degree and high density, the Li+ doped SBN displays a good energy storage performance. Since the ratio of Sr/Ba and (Sr + Ba)/Nb has not been changed, this work presents direct evidence for the effect of structural vacancy on crystal structure and properties, as well as inspiration for further work on unfilled tungsten bronze.

Molten salt synthesis of A-site disordered niobate microcrystals with tetragonal tungsten bronze structure

The anisometric templates with the same composition as the matrix is the key to the preparation of textured high entropy or multi-element doped ferroelectric ceramics. Here, we designed the A-site disordered niobate ((Na0.5K0.5)(Sr0.4Ba0.3Ca0.3)2Nb5O15) with tetragonal tungsten bronze structure and fabricated the needle-like microcrystals with a high aspect ratio by molten salt synthesis. The effects of process parameters (calcination temperature and molten salt content) on the morphology and chemical composition of products were investigated. It was found that a single tetragonal tungsten bronze structure phase could be obtained at calcination temperatures up to 1200 ℃. With the increase of molten salt content, the size of product particles become more uniform. The TEM results suggested that the obtained needle-like particle was a single crystal and had a uniform distribution of elements. In addition, the photocatalytic properties of the microcrystals were evaluated by degrading the organic dye methylene blue (MB) under simulated sunlight conditions. The present work shows the potential of the A-site disordered niobate microcrystals with tetragonal tungsten bronze structure for the solar-driven remediation of polluted water.

Ultralow thermal conductivity and high thermopower of a novel high-entropy (Sr0.2Ba0.2La0.2Eu0.2Pb0.2)Nb2O6 with tungsten bronze structure

High-entropy oxides (HEOs) have been extensively investigated as potential materials for thermoelectric applications. Here, a novel high-entropy (Sr0.2Ba0.2La0.2Eu0.2Pb0.2)Nb2O6 with a tungsten bronze structure was synthesized by solid-state method at high temperature, and tested its thermoelectric properties. The XRD, SEM-EDS, and TEM results showcase the successful integration of multi-component cations into the A site, yielding a single-phase material. The intrinsic thermal conductivity of this material is relatively low, measuring 0.78 W·m−1·K−1 at 323 K, thereby demonstrating exceptional thermal insulation behavior. This can be attributed to the highly disordered arrangement of multi-component cations with a distinctive high entropy configuration. At T = 1073 K, the high-entropy ceramic possesses the maximum power factor of 426.50 mW·m−1·K−2. As a result, an impressive thermoelectric figure of merit, ZT = 0.26, was achieved at 1073 K due to synergistic improvements in both electron transport and phonon scattering enabled by the high-entropy engineering strategy.