Ionic thermoelectric materials based on the Soret effect are promising for harvesting low-grade thermal energy owing to their high thermopower, mechanical flexibility, and low thermal conductivity. However, their practical performance is fundamentally limited by the long-standing trade-off between ionic conductivity and mechanical robustness in ionogels. Here, we report a defect- and structure-engineered ionic thermoelectric ionogel enabled by one-dimensional SrTiO3 nanofibers with oxygen vacancies. The ferroelectric polarization and oxygen-vacancy-rich surfaces of SrTiO3 generate built-in local electric fields and ion-selective anchoring sites, which promote ion dissociation and amplify cation-anion migration asymmetry. Meanwhile, the one-dimensional nanofiber architecture suppresses polymer crystallization, forms continuous ion-transport pathways, and reinforces the polymer network. As a result, the optimized ionogel achieves a high ionic thermopower of up to 17.95 mVK-1 and an ionic conductivity of 7.72 mScm-1, together with exceptional stretchability and long-term stability. Furthermore, an ionic thermoelectric capacitor is demonstrated, enabling controllable thermal energy harvesting and storage through capacitive processes. This work establishes a general design principle for decoupling ion transport and mechanical performance in ionic thermoelectric systems.

High-pressure processing provides an effective yet underexplored route for tuning atomic ordering and crystallization pathways in oxide glasses. Here, we demonstrate a pressure-guided crystallization strategy for the widely-used family of Li2O-Al2O3-SiO2 glass-ceramics, which enables controlled phase evolution and reorganization of medium-range order (MRO), leading to simultaneous strengthening and toughening. Using in-situ high-pressure heat treatment (HP-HT) combined with multimodal atomic characterization, we show that application of pressure stabilizes virgilite together with Li2SiO3 and Li2Si2O5 phases and also drives the reconstruction of MRO units while preserving the short-range glass network topology. Such pressure-directed phase selection and medium-range structural reorganization promote densification and a rise in crystallized volume fraction, leading to improved mechanical properties. Under isothermal conditions at 740 degrees C, pressure promotes virgilite formation, modifies the LS2-related phase equilibrium, increases crystallinity, and densifies the residual glassy matrix. As a result, density, hardness, and Young's modulus increase markedly, with the highest modulus reaching E approximate to 121 GPa at 2.5 GPa. Crack initiation resistance (CR), however, shows a non-monotonic dependence on pressure, increasing to a maximum at 0.5 GPa-more than five times that of the ambient-pressure sample-then decreasing at intermediate pressures and recovering slightly at 2.5 GPa. This pressure-dependent CR response is governed by the competition among pressure-assisted densification, phase evolution, and thermalmismatch-induced stress heterogeneity. These results establish pressure-guided crystallization as a viable route for tailoring MRO, phase assemblage, and mechanical response in LAS glass-ceramics.

Developing thermally stable bimetallic alloy clusters for furfural hydrogenation remains a significant challenge because high-temperature alloying readily causes metal migration and particle growth. In this study, ultrasmall Pt-based bimetallic clusters are constructed on a mesoporous carbon nanosphere (PtM-S/MCS) by combining a sulfur-anchored strategy to achieve efficient tandem conversion of furfural (FFA) into furfuryl alcohol (FOL). Characterization results show that the resultant materials possess a mesoporous carbon nanosphere (MCS) with a large specific surface area (1,482.8 m2 g-1) and uniform mesopores (≈ 7 nm), in which PtCo alloy clusters with a particle size of 2.1 nm are homogeneously dispersed. The strategy is further extended to PtFe-S/MCS and PtCu-S/MCS, demonstrating its applicability to different Pt-based bimetallic systems. In the selective hydrogenation of FFA, the PtCo-S/MCS catalyst achieves a 98.9% FOL yield. The enhanced performance arises from the cooperative effects of sulfur anchoring, mesoporous confinement, and PtCo alloy formation.

The development of transparent glass-ceramics that simultaneously exhibit high fracture toughness, hardness, and optical transparency poses a significant scientific challenge, since enhancement of mechanical properties often compromises visible light transmission via crystallinity-induced scattering. Here, we report novel MgO-Al2O3-SiO2-ZnO-B2O3 glass-ceramics that overcome this trade-off, attaining high indentation fracture toughness (K IC(ind) = 2.1 MPa & centerdot;m1/2) and Vickers hardness (H V = 9.2 GPa) while simultaneously achieving good visible light transmittance (similar to 74% at 550 nm). The crystallization behavior and residual stress distribution are governed by the interplay between ZnO and B2O3, where ZnO acts as a network modifier to enhance Mg2+ mobility and alpha-cordierite crystallization, while B2O3 stabilizes the glass matrix through tetrahedral BO4 linkages, suppressing interfacial stress gradients. Molecular dynamics simulations reveal that thermal expansion mismatch between alpha-cordierite and MgAl2Si3O10 with the glass matrix generates residual compressive stresses, enhancing crack deflection and interfacial cohesion. A dual-phase microstructure comprising alpha-cordierite (rigid hexagonal framework) and MgAl2Si3O10 (energy-dissipating interfaces) enables mechanical resilience, while controlled crystal size minimizes light scattering. Surface crystallization induces compressive stress (ZC-6, -368.4 MPa) analogous to that produced via ion-exchange strengthening, effectively counteracting tensile stresses at crack initiation sites. The optimized ZC-6 composition exemplifies this balance between mechanical and optical performance, surpassing many conventional glass-ceramics in both fracture toughness and transparency. This work establishes a novel paradigm for designing high-performance transparent materials, bridging the gap between optical clarity and mechanical resilience.

Zn-based halides have garnered much attention because of their high stability and environmental friendliness. In anti-counterfeiting applications, fluorescent materials with low cost, low toxicity, and tunable multicolor emission are highly desired. In this work, we demonstrate that diverse emission colors can be achieved by doping various ions into lead-free C3ZnBr5, forming Cs3Zn1-xCuxBr5-x (x = 0.01-0.06), Cs3Zn1-xMnxBr5(x = 0.10-0.50) and Cs3-xZn1-xCexBr5 (x = 0.05-0.30) series. Copper doping induces blue emission centered at 460 nm with an FWHM of 80 nm; manganese doping yields green emission at 520 nm with an FWHM of 40 nm; and cerium doping produces ultraviolet emission around 382 nm with an FWHM of 70 nm. Leveraging the unique photoluminescent properties of Zn halides, we successfully applied the synthesized materials for anti-counterfeiting. Our results highlight that Zn-based halides as a promising family of lead-free phosphors for advanced optoelectronic and security applications.

Yttrium aluminum garnet (YAG) has garnered extensive attention and research interest as an ideal laser host material due to its excellent optical properties, mechanical strength, and stable physicochemical characteristics. This study successfully fabricated highly dense (99.8% relative density) YAG ceramics via high-specific-surface-area mesoporous YAG powders combined with spark plasma sintering (SPS) at 1400 degrees C under 60 MPa, with a dwell time of only 3 min. The as-fabricated dense YAG ceramics exhibited excellent mechanical properties, including a Vickers hardness (HV) of 15.02 GPa and a fracture toughness of 2.3 MPam(1/2). This research reveals the critical role of highly sinter-active mesoporous YAG powders in the low-temperature preparation of high-density YAG ceramics, while also providing a novel and important strategy for rapidly producing high-performance fine YAG ceramics at low sintering temperatures.

High-performance dielectric microwave absorbing materials (MAMs) face a persistent trade-off between impedance matching and attenuation due to the inherent coupling of real (ε') and imaginary (ε″) permittivity. Herein, a sequential interface engineering (SIE) strategy is proposed to achieve dielectric decoupling by stepwise constructing multi-phase heterointerfaces on reduced graphene oxide. Using a lacunary polyoxometalate [SiW9O34]10- as an atomically precise molecular scaffold to sequentially integrate Fe2+, Mn2+ and Gd3+, we programmed a controlled thermal evolution from single-phase FeWO4 to dual-phase FeWO4/MnWO4 and to tri-phase FeWO4/MnWO4/Gd2W2O9 heterostructures. This "interface-by-interface" assembly allows for a stable ε' baseline maintained by the tungsten-oxygen system, while ε″ is independently enhanced by the increasing density of heterojunctions. Specifically, the FeWO4/MnWO4 interface boosts interfacial polarization, elevating the minimum reflection loss (RLmin) from -42.95 dB to -60.39 dB. Subsequent introduction of Gd3+ induces a distinct Gd2W2O9 phase that diversifies polarization relaxation pathways, significantly broadening effective absorption bandwidth (EAB) from 6.08 to 8.24 GHz with a further improved RLmin to -62.43 dB. Density functional theory calculations confirm substantial interfacial charge transfer and built-in electric fields at each stage. This work establishes a rational "molecular-to-nano" paradigm for precision heterostructure design, offering a versatile blueprint for programming interfacial electronic environments for functional materials.

Wearable thermoelectric generators (WTEGs) are promising candidates for maintenance-free power sources in wearable electronics. However, conventional performance prediction and structural optimization of WTEGs often rely on simplified heat transfer coefficient (HTC) models with a constant convective heat transfer coefficient, which overlooks the complex fluid-solid interactions and may lead to significant inaccuracies under forced convection conditions. In this study, a three-dimensional conjugate heat transfer (CHT) model is developed under an idealized steady, laminar forced-convection baseline to investigate the impact of fluid-thermal coupling in Magnesium-based WTEG design, focusing on the cross-sectional area ratio, inter-leg spacing, and geometric shape. Our results demonstrate that while the HTC model can qualitatively capture the optimization trends, the quantitative predictions of output power can exhibit substantial deviations due to the non-uniform distribution of the local heat transfer coefficient. Furthermore, aerodynamically streamlined cylindrical legs significantly enhance convective heat transfer, leading to an output power improvement of similar to 17% compared with conventional cuboid legs, although the enhancement decreases to 6.3% in the 8-pair module because of architecture-dependent thermal masking and wake/electrode interactions. This work highlights the necessity of incorporating fluid-thermal coupling in device design and provides potential shape optimization strategies for Magnesium-based wearable thermoelectric devices within the studied open-structure forced-convection configuration.

Hierarchical structure engineering and multicomponent design are pivotal for developing high-performance electromagnetic wave (EMW) absorbers, however, conventional synthetic strategies still face significant challenges in simultaneously achieving precise control over multi-component, microstructural construction and size regulation. Herein, an asymmetric hierarchical metal-organic framework (MOF)-derived nanoporous carbon (NPC) composite is fabricated via a polyoxometalate (POM)-mediated coordination competition strategy. Tungsten-based POM (W-POM, Na3 [PW12O40]) acts as a dynamic structural modulator during Cu-MOF assembly. By competitively coordinating with Cu(II) ions against organic ligands, the W-POM precisely regulates Cu(II) ion release kinetics and nucleation, enabling concurrent control over precursor size (100-400 nm), morphology (evolving from octahedra to aggregated polyhedra), and composition. Subsequent pyrolysis transforms these W-POM@Cu-MOF precursors into a hierarchical architecture featuring asymmetrically grown Cu nanosheets on porous carbon matrix, alongside embedded Cu nanoparticles and W-POM-derived Na2WO4 heterostructures (Cu/W/NPC). This unique anisotropic configuration synergistically enhances microwave attenuation, where Cu nanosheets and porous matrix prolong propagation paths and induce multi-scattering, while the uniformly dispersed Na2WO4 and heterogeneous interfaces significantly boost interfacial polarization and dipole polarization. Consequently, the optimized nanocomposite exhibits superior EMW absorption performance, achieving a minimum reflection loss (RLmin) of-61.4 dB and a broad effective absorption bandwidth (EAB) of 6.64 GHz. COMSOL simulations quantitatively confirm the abundant interfaces and porous structures synergize polarization dissipation and multi-reflection mechanisms, optimizing impedance matching. Radar cross-section (RCS) simulations further demonstrate significant attenuation (29.84 dB m2), highlighting practical stealth utility. This work establishes a versatile POM-mediated coordination competition paradigm for architecturally and compositionally tailored MOF-derived advanced EMW absorbers.

Thermocell (TEC), as economical, simple, and stable-output ionic thermoelectric (i-TE) systems, provides a reliable solution for the effective utilization of low-grade heat and direct conversion to continuous electricity. However, prevalent issues in TEC, such as electrolyte leakage, low tensile toughness, and limitations in the fabrication of series/parallel planar devices, have restricted its practical applicability. Herein, a quasi-solid, fiber-shaped 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM BF4)-liquid crystal elastomer (E-LCE) based TEC is obtained by impregnation with I2/KI/EMIM BF4 solution, leveraging the chaotropic effect of BF4− and the interaction of EMIM+-I3− to expand the entropy and potential differences between the hot and cold electrodes, achieving a thermopower of −1.2 mV K−1. Furthermore, combining traditional weaving techniques and three-dimensional structural embedding design, an E-LCE-based TEC wristband is woven by integrating the TEC into an LCE ribbed textile, achieving accurate monitoring of the wearer’s body temperature, broadening the application scenarios of TEC and paving the way for its commercial applications in wearable devices and biomonitoring fields. This work uses Liquid Crystal Elastomer (LCE) as the substrate and employs I2/KI as the redox couple. The chaotropic effect of EMIM BF4 not only increases the entropy difference of the system but also serves as a supporting electrolyte to enlarge the potential difference, thereby synergistically improving the thermoelectric properties of the LCE based TEC. Finally, leveraging the mechanical advantages of the LCE material together with the stable and rapid voltage response of the LCE-based TEC, an LCE-based i-TE wristband was fabricated and applied for human body temperature monitoring.

The accurate prediction of tetrahedral boron fraction (N4) in multicomponent borate and borosilicate glasses remains a fundamental challenge in glass science, with significant implications for materials design in nuclear waste immobilization, pharmaceutical packaging, and advanced optics. Traditional analytical models fail to capture the complex compositional dependencies in high-dimensional oxide systems, particularly the wellknown boron anomaly phenomenon. This study presents a comprehensive machine learning framework for N4 prediction using an expanded dataset of 906 glass compositions encompassing 32 oxide components. We employed Q5 stratified sampling and Yeo-Johnson transformation to enhance data representativeness and model convergence. Among eight evaluated algorithms, Artificial Neural Network (ANN) demonstrated superior performance with test R2 = 0.8634, cross-validated R2 = 0.8872, and RMSE = 0.0789. SHAP-based interpretability analysis quantitatively recovered the boron anomaly, revealing Na2O as the most influential modifier and identifying competitive interactions between B2O3 and Al2O3. Two-dimensional partial dependence surfaces defined optimal compositional windows for maximizing N4, while Williams plot analysis confirmed 89.0% of test samples reside within the model's applicability domain. External validation on 60 independent compositions showed reasonable generalization within the applicability domain: overall R2 = 0.6741 dominated by a few extreme compositions, whereas the 80% of samples inside the leverage-based applicability domain are predicted with R2 = 0.7285 and the out-of-domain errors are chemically interpretable. This work advances predictive modeling of boron coordination in complex glass systems and provides actionable insights for compositionproperty optimization in borate and borosilicate glass engineering.

Alkali-free boroaluminosilicate glass (AFBG) serves as substrates for organic light emitting diode (OLED) displays and as through-glass-via (TGV) interposers, where controlled viscosity, coefficient of thermal expansion (CTE), and stiffness are essential. We substitute alkaline-earth oxides (RO) with rare-earth oxides (Re2O3 = La2O3 or Y2O3) and probe the resulting structure-property changes using thermomechanical testing, Raman spectroscopy, and molecular dynamics (MD) simulations. Relative to the reference sample, Re2O3 lowers the working temperature from 1432 degrees C to similar to 1220-1300 degrees C while increasing the glass transition temperature and the strain point (more strongly for Y2O3). The CTE varies non-monotonically, peaking near 3 mol% Re2O3, consistent with initial network depolymerization followed by medium-range restiffening at higher loadings. Young's modulus rises by similar to 6-7% (approximate to 84 -> 90 GPa) with little change in nanohardness; density increases monotonically, more for La2O3 than Y2O3. Raman and MD together support a two-stage mechanism: Re-assisted depolymerization at low additions (BO down arrow/NBO up arrow, Q(4)-> Q(3)/Q(2), ring expansion), followed by partial repolymerization and medium-range stiffening at higher loadings (captured experimentally; under-represented in MD). Practically, Y2O3 yields a better stiffness-density balance, whereas La2O3 maximizes densification. These insights establish composition-structure-property correlations that enable targeted CTE and stiffness tuning for next-generation OLED and TGV glass substrates.

Lead-free Cs3Cu2I5 perovskite nanocrystals (NCs) are promising candidates for optoelectronic applications owing to their non-toxicity and intrinsic blue emission. However, their practical application is hindered by defect-dominated low photoluminescence quantum yield (PLQY) and poor environmental stability. Herein, we propose an ultrafast liquid-nitrogen (LN) quenching strategy integrated with one-pot synthesis, which delivers an ultra-high cooling rate of 35 K/s faster than conventional ice-water (IW) cooling (1 K/s). This abrupt thermal termination effectively suppresses Ostwald ripening, ion migration and surface ligand detachment, thereby promoting uniform size distribution, inducing lattice contraction and reducing the non-radiative defects. The obtained Cs3Cu2I5 NCs exhibit a remarkable PLQY up to 85% and exceptional stability, maintaining beyond 80% of initial PL intensity after ambient storage for 35 days, aqueous exposure for 36 hand continuous UV irradiation for 48 h. Moreover, the LN-quenched NCs were successfully integrated into X-ray scintillator film achieving a spatial resolution of 10 lp/mm, and their colloidal ink enabled stimulus-responsive information encryption and fluorescence anti-counterfeiting patterns, attributed to enhanced self-trapped exciton (STE) emission and robust structural integrity. This work establishes ultrafast LN quenching as a universal and feasible strategy for fabricating highly luminescent and stable perovskite NCs, paving the way for multifunctional optoelectronic applications.

Ultraviolet-excited single-matrix broadband white-light lead-free perovskite phosphors have attracted extensive attention due to their environmental friendliness and high stability. However, single-activator systems typically struggle to achieve full visible-spectrum coverage. Here, we report a novel single-matrix white phosphor, Cs2Sn0.65-yZr0.15Cl6: 20%Bi/yTe, synthesized via a simple precipitation method through Bi3+/Te4+ dual-activator co-doping in a Zr4+-optimized Cs2SnCl6 host. Under 365 nm UV excitation, the Bi3+ center produces blue emission via 3P0→1S0 transition and [BiSn+VCl] defect-mediated recombination, whereas the Te4+ center generates long-lived yellow emission through self-trapped exciton (STE) relaxation. The energy transfer from Bi3+ to Te4+ is systematically investigated, achieving an efficiency of 85% at the optimal Te4+ concentration of 0.5 mol%. The phosphor exhibits a photoluminescence quantum yield (PLQY) of 58.02%, along with good thermal and water stability. When integrated with a 365 nm UV LED chip, the fabricated white light-emitting diode (WLED) device achieves CIE chromaticity coordinates of (0.3342, 0.3631), a color rendering index (CRI) of 75.8, and a correlated color temperature (CCT) of 4849 K, all close to standard white light. These results demonstrate that Bi3+/Te4+ co-doped Cs2Sn0.85Zr0.15Cl6 phosphor is a promising candidate for single-matrix white phosphors in UV-excited WLED applications.

Organic-inorganic hybrid metal halides (OIHMHs) have attracted considerable attention because of their superior optoelectronic properties and structural versatility, yet one-dimensional (1D) OIHMHs remain the least studied relative to their 0D, 2D, and 3D counterparts. Here, a new 1D blue-emitting hybrid cadmium chloride phosphor, (MBI)CdCl4·H2O, was constructed using 2-methylbenzimidazole (MBI) as the organic ligand. It crystallizes in the monoclinic P21/c space group, consisting of distorted [CdCl6]4- octahedra connected via edge sharing. Incorporation of Sb3+ ions with stereochemically active 5s2 lone-pair electrons yields (MBI)Cd0.7Sb0.2Cl4·H2O, which exhibits highly efficient yellow emission with a photoluminescence quantum yield (PLQY) of 92.0%. In addition, doping with high-spin Mn2+ ions produces photoluminescent (MBI)Cd0.85Mn0.15Cl4·H2O crystals with a PLQY of 16.7%. Leveraging the tunable luminescence of this Cd halide, these materials were further demonstrated in anticounterfeiting and information encryption applications, highlighting a promising avenue for the development of functional metal halides.

Intermetallic nanoparticles (iNPs) exhibit ordered superlattice structures characterized by unique properties, for example, long-range ordering, robust metallic bonding and site-isolation effects. Multicomponent (>2) iNPs are particularly interesting for the development of advanced metallic catalysts for electrochemical applications. Integration of iNPs within mesoporous carbon nanostructures enhances mass and electron transfer during electrolysis and provides a protective mesoporous confinement that prevents iNP sintering and loss during operation. Here we describe a generalized two-step strategy to integrate iNPs with up to eight metal components into mesoporous carbon nanostructures that allows control over the ordering degree, phases and morphology. Ligand-assisted interfacial assembly of monomicelles on diverse metal substrates (using a laboratory-made amphiphilic copolymer as a structure-directing agent, with dopamine acting as both carbon precursor and metal-coordinating ligand) results in mesostructured metal-organic superstructures. All of the examples described have at least one noble metal (Pt or Pd) combined with transition metal elements (for example, Fe, Co, among others). Thermal processing of these metal-organic superstructures in an ammonia (NH3) atmosphere induces the formation of chemically ordered iNPs while simultaneously creating the mesoporous structure. The Protocol also includes procedures for two example electrochemical applications: the oxygen reduction reaction and nitrate reduction reaction for NH3 production. The entire synthetic procedure takes ~5 d, while physical characterization via electron microscopy, X-ray diffraction and nitrogen sorption isotherms require ~2 d. Investigating the catalytic mechanisms, utilizing in situ Fourier-transform infrared spectroscopy and online differential electrochemical mass analysis typically take 4-6 h for electrocatalytic reactions.

Lead-free red emissive hybrid Mn2+-based metal halides have emerged as promising phosphors for lighting and display applications owing to their environmental friendliness and d-d transition. However, simultaneously enhancing emission efficiency and narrowing the red-emission bandwidth of Mn2+ halide phosphors remains challenging. Here, we report an HCl-assisted precipitation strategy for synthesizing (CH3)4NMnCl3 phosphors. The introduction of HCl creates an acidic and chloride-rich chemical environment, thereby improving crystallization and luminescence emission efficiency. The as-prepared (CH3)4NMnCl3 phosphors exhibit a red emission at 629 nm with a photoluminescence quantum yield of 70.77% and a narrow full width at half-maximum of 75.16 nm. The phosphors have good thermal stability (retained 80.77% of initial PL intensity at 423 K) and thermal-cycling stability. The as-fabricated light-emitting diodes (LEDs) using (CH3)4NMnCl3 as red emitters exhibit excellent operational stability, with 98.29% of initial luminous efficiency (LE) being maintained after 224 h of continuous operation. In addition, the assembled white LED delivers an LE of 88.41 lm/W and achieves a wide gamut covering 101.7% of the NTSC 1931. These results provide an effective strategy for achieving efficient and narrow-band hybrid Mn2+ halide phosphors, offering a promising lead-free emitter for wide-gamut display applications.

Developing efficient red-emitting phosphors with broad near-ultraviolet (NUV) excitation is crucial for high-quality white LEDs. However, conventional Eu3+-activated perovskites suffer from limited Mo6+ solubility due to structural instability induced by the strong second-order Jahn-Teller effect of Mo6+, especially in highly symmetric hosts. Herein, we propose a structural engineering strategy based on A-site cationic disordering to overcome this limitation. By substituting Ca2+ for Mg2+ in the LiLaMgWO6 host, we successfully disrupt the layered ordering of A-site cations and obtain an A-site-disordered double perovskite-CaLaLiWO6:Eu3+. This disordered framework effectively mitigates lattice strain upon Mo6+ incorporation, enabling high-concentration Mo6+ doping without phase segregation. Consequently, the optimized phosphor CaLa0.9Eu0.1LiW1-xMoxO6 exhibits intense broadband excitation (300-450 nm) via the [MoO6] charge transfer band, combined with dominant red emission (5D0 -> 7F2 at 617 nm) and a high R/O ratio of 9.1, indicating low local symmetry around Eu3+. The material achieves a color purity of 97% and demonstrates excellent performance in a NUV-pumped WLED, delivering a high color rendering index (Ra = 89.3) and a significantly enhanced R9 value (60.0). Moreover, the linear dependence of its emission intensity on temperature highlights its potential for optical thermometry applications. This work establishes A-site disordering as a viable approach to simultaneously achieve high dopant solubility and favorable low-symmetry luminescent centers, offering a new paradigm for designing next-generation red phosphors.

ABSTRACT Laser‐driven lighting demands robust color converters with broad, continuous spectra to achieve high‐fidelity illumination, yet conventional phosphors often suffer from spectral deficiencies that lower the color rendering index (CRI) and cause visual discomfort. To address this, we develop CaF 2 ‐Cs 2 Na 0.7 Ag 0.3 In 0.97 Bi 0.03 Cl 6 composite phosphor ceramics (CPCs) utilizing spark plasma sintering at temperatures below 490°C. A fluoride‐mediated defect compensation mechanism, in which F − ions migrate from the CaF 2 matrix into Cl − vacancies of the double perovskite, simultaneously facilitates full densification and passivates non‐radiative recombination centers. This dual effect enables the CPCs to emit warm white light with a full width at half maximum of 224 nm and a near‐unity relative photoluminescence quantum yield. The CPCs also exhibit superior stability against heat, moisture, and laser irradiation, together with a high thermal conductivity of 9.4 W·m − 1 ·K − 1 at 25°C. A prototype laser‐driven lighting device based on these CPCs delivers high‐quality warm white light with a CRI (R a ) of 96. This work establishes a fluoride‐compensation low‐temperature sintering strategy for robust lead‐free double perovskite‐embedded CPCs with broadband emission, targeting high‐fidelity laser‐driven lighting.