Table of Content

20 June 2026, Volume 55 Issue 6

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Reviews

Research Status and Application Prospects and of Colored Artificial Diamonds

JU Yifang, XIA Jiaqi, ZHANG Hong, ZHANG Shulong, HANG Yin

2026, 55(6):  817-829.  doi:10.16553/j.cnki.issn1000-985x.2026.0005

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Colored artificial diamonds exhibit significant application potential in high-end jewelry，precision optical devices，quantum technology and ultra-wide bandgap semiconductors，owing to their vibrant and tunable colors，excellent physical and chemical properties，outstanding optical performance and controllable production costs. Through advanced synthesis techniques，these diamonds are imbued with rich colors based on a coloring mechanism fundamentally distinct from that of natural diamonds，with the core principle lying in the precise design and control of defects within the crystal lattice. Such defect engineering not only enables the diverse manifestation of diamond colors，but also expands the application scope of colored diamonds from the traditional jewelry sector to a series of cutting-edge high-tech fields. This paper provides a systematic review of the coloration principles，preparation methods and current research status of colored synthetic diamonds. It analyzes the technical pathways and doping mechanisms for producing diamonds of specific colors，examines their market development trends in jewelry，and analyses the current applications and future prospects in frontier areas such as quantum sensing，ultra-wide bandgap semiconductors and electrochemistry.

Research Progress on Application of Pd-Based Anode Catalysts in Direct Ethanol Fuel Cells

LIANG Yinyin, NAN Xu, WEI Bangzhi, WU Zhichao, LIU Fei, ZHANG Qin, WANG Dun

2026, 55(6):  830-842.  doi:10.16553/j.cnki.issn1000-985x.2026.0029

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Under the context of “dual carbon” goals （carbon peaking and carbon neutrality），direct ethanol fuel cells （DEFCs） have been extensively investigated owing to their high efficiency and low pollution emissions. The energy conversion process of DEFCs is heavily dependent upon the efficacy of catalysts，whereas the anode catalysts are prone to deactivation caused by the accumulation and adsorption of reaction intermediates. The catalytic activity of materials can be substantially enhanced and the efficient utilization of catalysts can be achieved through rational structural design. Based on this perspective，starting from the construction strategies of Pd-based anode catalysts，the current design concepts for anode catalysts in DEFCs are explicitly categorized into three classes of morphology engineering based on material structures，electronic state modulation based on active sites，and synergistic optimization based on support and interface engineering. The Pd-based catalyst performance and design strategies in alkaline are systematically compared. Meanwhile，combined with the superior catalytic performance demonstrated in ethanol oxidation，the control mechanisms of poisoning intermediates are further analyzed as follows： 1） C—C bond cleavage pathway regulation—poisoning precursor elimination； 2） d-band center modulation—the weakening of adsorption of poisoning species； 3） enhanced supply of adsorbed hydroxyl species （OH_ads）—accelerated oxidative removal. Furthermore，catalyst stability is addressed as a central scientific issue，with a systematic review of the major deactivation mechanisms of Pd-based catalysts （Pd dissolution，Ostwald ripening，support corrosion，and strong adsorption of intermediates） and corresponding design countermeasures. Regarding current research on Pd-based anode catalysts，priority should be given to solve the stability bottleneck of catalysts while considering catalyst stability. Combined with in-situ characterization techniques，the exploration and interpretation of catalytic mechanisms should be conducted，followed by synergistic optimization from multiple dimensions including composition，structure，and support materials，thereby gradually overcoming the challenges in scalable and controllable construction of highly efficient and stable Pd-based catalysts.

Research Articles

Growth of BPO₄ Crystals from Li₂O-B₂O₃ Flux

PAN Jiayue, JING Fangli, LIU Hongjun, HU Zhanggui, WU Yicheng

2026, 55(6):  843-850.  doi:10.16553/j.cnki.issn1000-985x.2026.0044

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BPO₄ crystal has attracted considerable interest as a nonlinear optical （NLO） material due to its extremely short ultraviolet （UV） cutoff edge，strong powder second-harmonic generation （SHG） response，and high physicochemical stability. In this work，high-quality BPO₄ single crystals were successfully grown via the top-seeded solution growth （TSSG） method employing a Li₂O-B₂O₃ flux，and their crystalline quality，optical properties，and mechanical properties were systematically investigated. The Li₂O-B₂O₃ flux system exhibits low volatility and remains transparent at high temperatures，enabling real-time monitoring of the growth process. The as-grown crystals show a narrow rocking curve with a full width at half maximum （FWHM） of 0.008°，confirming the efficacy of this flux in producing high quality crystals. Raman and infrared spectroscopy are carefully elucidated to confirm the ion group in the BPO₄ crystal. Optical transmission measurements reveal that the crystal possesses a broad transparent range，with UV and IR cutoff edges extending to 133 and 4 270 nm，respectively，underscoring its potential for deep-UV applications. Furthermore，nanoindentation tests demonstrate its robust mechanical stability，yielding a hardness of approximately 12.75 GPa and a reduced modulus of about 153.37 GPa. In summary，Li₂O-B₂O₃ flux exhibits low volatility and high solution transparency，proving to be an excellent medium for the growth of high-quality BPO₄ crystals. The combination of an extremely short UV cutoff edge，wide spectral transparency，and favorable mechanical properties positions BPO₄ as a promising candidate for next-generation deep-UV NLO materials.

Characterization of Fundamental Properties of Large-Sized Calcium Fluoride Crystals

WANG Xu, JIANG Lan, WANG Xiaoxiang, WANG Qingguo, WANG Deyong, JIA Jian

2026, 55(6):  851-857.  doi:10.16553/j.cnki.issn1000-985x.2026.0023

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Calcium fluoride （CaF₂） crystals，due to their low refractive index and high resistance to laser damage，are widely used in achromatic lenses and high-power laser systems. Especially their high light transmittance in the deep ultraviolet band makes them an irreplaceable lens material for DUV lithography machines. In this study，large-sized CaF₂ crystals with a diameter of 320 mm were prepared by the crucible descent method，and the mechanical properties，thermal properties and optical quality of the crystals were characterized and analyzed. The results show that the shear fracture strength of the （111） crystal plane of the grown CaF₂ crystal is 9.2 MPa and the flexural fracture strength is 60 MPa. The Vickers hardness test result of the （110） crystal plane is 7.69% higher than that of the （111） crystal plane，and the stress fringe distribution inside the crystal is relatively uniform. The mean stress birefringence of the CaF₂ crystal with a specification of 148 mm×148 mm×60 mm is 0.8 nm/cm. The optical uniformity PV value of the CaF₂ crystal with a diameter of 150 mm is 0.579×10^-6，and the transmittance in the 190~800 nm band at room temperature is above 90%.

Growth and Thermoelectric Properties of Cd-Doped InSb Crystals

SHI Qianhui, CHEN Hao, LIN Siqi, YUE Xiaofei, LIU Xuechao, JIN Min

2026, 55(6):  858-866.  doi:10.16553/j.cnki.issn1000-985x.2026.0022

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As an important group III-V narrow bandgap compound semiconductor，InSb crystals have been widely used in infrared detection and imaging，magnetoresistive sensing and high-speed electronic devices owing to their excellent optoelectronic and transport properties. Thermoelectric technology enables direct conversion between heat and electricity based on the Seebeck and Peltier effects. Despite their mature applications in traditional electronic fields，the potential of InSb crystals in thermoelectric energy conversion has not been fully explored. Therefore，optimizing the thermoelectric property of InSb via elemental doping is of great significance. This work systematically investigates the growth，crystal structure，thermoelectric property，and mechanical properties of Cd-doped InSb crystals. Three types of crystals，including InSb，In_0.99Cd_0.01Sb，and In_0.9Cd_0.1Sb，were grown by the Bridgman method. X-ray diffraction （XRD） analysis shows that the powder diffraction patterns agree well with the standard data，confirming a cubic zinc-blende structure with a space group of F43m. XRD pattern of the cleaved surface exhibits a single diffraction peak corresponding to the （220） plane，indicating excellent single-crystal characteristics. Scanning electron microscopy combined with energy-dispersive spectroscopy mapping confirms the homogeneous distribution of In，Sb，and doped Cd elements within the crystals. Raman spectroscopy reveals that the characteristic peaks of InSb exhibit a gradual redshift with increasing Cd doping concentration，further confirming the effective incorporation of Cd into the InSb lattice. Cd doping also induces a transition in the conduction type from N-type to P-type，which is mainly attributed to the introduction of hole carriers via Cd substitution at In sites. The pristine InSb crystal exhibits a power factor of 0.43 μW·cm^-1·K^-2 at room temperature. Upon Cd doping，the room-temperature power factor is significantly enhanced，reaching 5.9 and 5.2 μW·cm^-1·K^-2 for the In_0.99Cd_0.01Sb and In_0.9Cd_0.1Sb crystals，respectively. At 723 K，the thermoelectric power factor of the InSb sample increases from 8.8 μW·cm^-1·K^-2 to 12.7 μW·cm^-1·K^-2 by Cd doping. Meanwhile，defect scattering introduced by Cd incorporation enhances phonon scattering，leading to a significant reduction in thermal conductivity with increasing Cd concentration. The intrinsic InSb crystal exhibits a room-temperature thermal conductivity of 16.4 W·m^-1·K^-1. The thermal conductivity decreases to 8.8 W·m^-1·K^-1 for the In_0.9Cd_0.1Sb crystal at room temperature and further decreases to 3.4 W·m^-1·K^-1 at 723 K. Due to the synergistic optimization of the electrical and thermal transport properties induced by Cd doping，a thermoelectric figure of merit （zT） of 0.19 is achieved at 723 K in the In_0.9Cd_0.1Sb crystal，representing an enhancement of approximately 46% compared to that of the pristine InSb crystal. Mechanical testing indicates that an increase in Cd doping concentration leads to a reduction in the maximum indentation depth of the crystal，with the hardness increasing from 2.95 GPa to 3.15 GPa and the elastic modulus increasing from 56.36 GPa to 73.54 GPa. This work provides a feasible doping strategy for improving the thermoelectric performance of InSb crystals and demonstrates that Cd-doped InSb exhibits promising potential for thermoelectric applications in the medium-temperature range.

Effect of High-Temperature Annealing on Optical Properties of AlN Crystals

ZHANG Ying, XU Zongwei, WANG Zenghua, CHENG Hongjuan

2026, 55(6):  867-877.  doi:10.16553/j.cnki.issn1000-985x.2026.0042

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In this paper，AlN single crystals were grown by physical vapor transport method and subjected to high-temperature annealing treatment. By adjusting the high-temperature annealing time，temperature and other parameters，AlN single crystals with high transmission performance in the deep-ultraviolet band were successfully obtained. The surface morphology，crystalline quality and optical properties were systematically characterized. The results indicate that high-temperature annealing process effectively reduces the defect density and significantly improves the crystalline quality of AlN crystals. Specifically，the full width at half maximum of （0002） plane rocking curve decreases from 91.2″ to 28.5″. However，high annealing temperature （1 900 ℃） leads thermal corrosion morphology on the wafer surface and there is no transmittance in the deep-ultraviolet and visible light regions. The high-temperature annealing process has no significant effect on the optical properties of the central colorless region of the AlN wafer，and significantly improves the optical transmission performance of the colored edge region. Compared with AlN wafers before annealing，the most significant effect on the improvement of optical properties is achieved under annealing process at 1 800 ℃ for 7 h. The transmittance at 265 nm increases from 23.59% to 48.61%，and the corresponding absorption coefficient decreases from 45.26 cm^-1 to 22.59 cm^-1. The research provides theoretical guidance for improving the performance of AlN-based optoelectronic devices.

Stress Simulation, Thermal Bonding, and Growth of 2-Inch Aluminum Nitride Single Crystals

GAO Fei, XIN Qian, WANG Yingmin, CHENG Hongjuan, WANG Zenghua

2026, 55(6):  878-885.  doi:10.16553/j.cnki.issn1000-985x.2026.0031

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This paper，focusing on the stress regulation，thermal bonding process，and high-quality thick-crystal growth of 2-inch aluminum nitride （AlN） single crystals，performed systematic computational simulations and single-crystal growth experiments. It reveals the mechanism of cooling-induced thermal stress imposed on AlN single crystals by different substrate materials，and elucidates the intrinsic correlation between the properties of metal substrates and the residual stress of the crystals，providing theoretical support for the substrate selection in AlN single-crystal growth. Moreover，relying on simulation technology，an innovative low-stress thermal bonding process for 2-inch AlN is achieved，addressing the stress-induced cracking problem encountered during the high-temperature thermal bonding of AlN seed crystals. Meanwhile，by integrating simulation with structural optimization design，the thick-growth technology is successfully broken through，and a 2-inch high-quality AlN single crystal with a thickness of 10.8 mm is fabricated. The full width at half maximum （FWHM） of the （002） high-resolution X-ray diffraction （HRXRD） rocking curve of the wafer is as low as 51.67″.

Effect of Seed Off-Axis Angles on Distribution of Basal Plane Dislocations in Top-Seeded Solution Growth of SiC Crystals

LUAN Sen, QI Xiaofang, MA Wencheng, XU Yongkuan

2026, 55(6):  886-897.  doi:10.16553/j.cnki.issn1000-985x.xb2026.0021

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Basal plane dislocations （BPDs） are critical defects that severely degrade the quality of 4H-silicon carbide （SiC） crystal and the performance of 4H-SiC based devices. The top-seeded solution growth （TSSG） method is promising for high-quality SiC crystals with its near-thermodynamic equilibrium conditions. However，the distribution of thermal stress and BPDs is not fully understood in the TSSG growth of 4H-SiC crystals. Both on-axis and off-axis seeds are widely used in the industrial TSSG processes. To investigate the effect of seed off-axis angle （θ_off） on thermal stress and BPDs in 4H-SiC crystals grown by the TSSG method，a multi-physics coupled model was developed in this study by integrating global heat transfer，three-dimensional thermoelastic stress analysis，and the Alexander-Haasen dislocation evolution model. The resolved shear stress （RSS） and BPDs density distributions in 4H-SiC crystals grown at off-axis angles of 0°，4°，60°，and 90° were systematically simulated and analyzed. The results show that the seed off-axis angle critically affects the RSS distribution at the growth interface. Under on-axis （θ_off=0°） growth，the RSS exhibits a highly symmetric，low-stress state，with stress near the center approaching zero and only minor perturbations at the edge. At the θ_off is 4°，the RSS shows axisymmetric regional patterns. At the θ_off is 60°，the RSS transitions to a fourfold symmetric distribution with alternating tensile and compressive stresses，and the stress amplitude increases by an order of magnitude compared to that at θ_off ≤4°. At the θ_off is 90°，the RSS becomes fully fourfold symmetric distribution. Under all conditions，the maximum RSS on the growth surface is lower than that on the seed back surface，and high-stress regions consistently concentrate at the crystal periphery. The density and distribution of BPDs closely correlate with RSS. Under on-axis growth，BPDs exhibit a sixfold symmetric distribution. As the θ_off increases，the BPDs distribution gradually transitions to fourfold symmetric distribution，and the overall BPDs density increases significantly. At the θ_off are 60° and 90°，the maximum BPDs density reaches approximately 10⁵ cm^-2，which is two orders of magnitude higher than that at 4° （approximately 10³ cm^-2）. This substantial increase indicates that large θ_off promote BPDs multiplication and are detrimental to high-quality crystal growth. In addition，the BPDs density is consistently higher on the seed back surface than on the growth surface，and high-BPDs regions coincide with high-RSS regions at the crystal periphery. This study elucidates the correlation among the seed off-axis angle，thermal stress field，and BPDs distribution in 4H-SiC crystals grown by the TSSG method. The findings demonstrate that using a seed with a small off-axis angle （≤4°） effectively suppresses BPD generation，thereby facilitating the growth of high-quality 4H-SiC single crystals. These results provide theoretical guidance for optimizing the TSSG process to achieve low defect density and high crystalline perfection.

Optimizing Friction Coefficient of Crystalline Silicon Surfaces Using Modified Cutting Fluids

ZHU Zidan, GAO Bangzhi, JI Mengxia, CHEN Ming, WANG Yicheng, LIU Fujie, XU Hui, ZHANG Ming

2026, 55(6):  898-909.  doi:10.16553/j.cnki.issn1000-985x.2026.0017

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Driven by the global goals of carbon peak and carbon neutrality，the photovoltaic （PV） industry has become pivotal to energy transition，with crystalline silicon cells dominating over 95% of the PV market. However，commercially available crystalline silicon cutting fluids suffer from deficiencies such as inadequate dispersion and discharge of silicon powder，poor lubricity，and weak recyclability. These shortcomings severely compromise the surface precision of crystalline silicon and hinder the development of the photovoltaic industry. This study aims to overcome the aforementioned shortcomings of crystalline silicon cutting fluids by investigating the impact of different ion-liquid modified cutting fluids on crystalline silicon surface quality during the cutting process. Test results indicate that the modified cutting fluid，which incorporates 1% by mass of 1-methyl-3-octylimidazole chloride salt （［OMIM］Cl） as an ionic liquid into commercial cutting fluids，demonstrates the optimal performance. Its pH value is 6.26，the viscosity drops to 64.39 mPa·s，surface tension lowers to 24.07 mN/m，contact angle minimizes，and wetting penetration capability maximizes. Compared to the commercial cutting fluid，its friction coefficient decreases by over 60%，and wear volume decreases by 26.1%. It demonstrated excellent performance in reducing friction and enhancing crystalline silicon surface quality，offering broad prospects for widespread application.

Growth, Quenching Mechanism, and Luminescent Properties of Mn⁴⁺∶K₂Ge₄O₉ Single Crystals

SONG Qingsong, LIU Jian, ZHANG Fan, ZHANG Chaoyi, WANG Wudi, CAO Xiao, QIAN Xinyu, TANG Huili, WANG Qingguo, ZHANG Chenbo, LIU Bo, XU Xiaodong, XU Jun

2026, 55(6):  910-929.  doi:10.16553/j.cnki.issn1000-985x.2026.0037

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Red-emitting luminescent materials constitute core components in solid-state lighting and display technologies，offering distinct advantages for high-color-rendering-index （CRI） white light-emitting diodes （wLEDs） and agricultural illumination. Commercial red phosphors currently rely heavily on rare-earth activators，such as Eu²⁺，Eu³⁺，and Sm³⁺. While these materials exhibit excellent luminescence via 4f-4f and 4f-5d transitions，inherent resource scarcity and complex extraction processes inflate costs，severely restricting their large-scale deployment. Consequently，developing efficient，rare-earth-free alternatives has emerged as a critical research frontier. In facility agriculture，specific light spectra precisely govern plant development. While blue light promotes vegetative growth，deep-red emission （~660 nm） is essential for flowering，fruiting，leaf expansion，and stem elongation，directly dictating crop maturation cycles and ultimate yields. Transition metal Mn⁴⁺ demonstrate exceptional suitability for agricultural applications，as their emission profile perfectly matches the peak absorption of plant phytochromes. Because the luminescent properties of Mn⁴⁺ depend heavily on the local crystal field，selecting an appropriate host lattice is paramount. K₂Ge₄O₉ （KGO） represents an ideal matrix. Here，Ge⁴⁺ perfectly matches Mn⁴⁺ in both ionic radius and valence state. Furthermore，its unique tetrahedral-octahedral composite framework provides the requisite ［GeO₆］ octahedral sites for Mn⁴⁺ incorporation. Despite these structural advantages，traditional Mn∶KGO polycrystalline phosphors suffer from poor photothermal stability，retaining less than 40% of their room-temperature emission intensity at 100 ℃，with underlying thermal quenching mechanisms remaining ambiguous. To address the severe thermal quenching bottleneck commonly observed in traditional Mn⁴⁺-doped polycrystalline oxide phosphors，a novel low-melting-point Mn∶KGO single crystal was successfully grown using the Czochralski method. Through density functional theory （DFT） calculations，a site-dependent dual thermal quenching mechanism within this system is elucidated. Specifically，Mn⁴⁺ occupying the Ge1 sites are restricted by parity selection rules，whereby a carrier autoionization process is triggered. Conversely，Mn⁴⁺ at the Ge2 sites，which serve as the primary luminescent centers，are subjected to strong covalent hybridization with the valence band，forcing the charge transfer state energy to be lowered significantly. Furthermore，it is demonstrated that non-radiative transition pathways are effectively suppressed by the continuous lattice structure of the single crystal. Consequently，the thermal quenching temperature of the crystal is elevated by 6.2 ℃，and the internal quantum efficiency （IQE） is substantially increased by 44%，reaching a remarkable value of 48.3%. In terms of device application evaluations，it was observed that upon the integration of this single crystal into wLED packages，the CRI is improved by 7.5，and the correlated color temperature （CCT） is reduced by over 2 000 K，successfully driving a transition from cool to warm white light. Simultaneously，the 664 nm deep-red emission spectrum of the crystal is found to be closely matched with the characteristic absorption bands of plant phytochromes. Ultimately，a low-melting-point Mn⁴⁺-doped oxide crystal is developed in this study，which provides a highly promising single-crystal red-emitting material for high-power solid-state lighting and plant growth illumination applications.

Effect of Oxalic Acid Pretreatment on Low-Temperature Densification and Optical Properties of Y₂O₃ Transparent Ceramics

LIN Haining, CHEN Jian, HUANG Jiquan, LIU Xin, GUO Wang

2026, 55(6):  930-939.  doi:10.16553/j.cnki.issn1000-985x.2026.0013

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Yttrium oxide （Y₂O₃） transparent ceramics have been widely studied for infrared windows，corrosion-resistant components，solid-state lasers，and scintillator hosts because of their broad optical transparency range，excellent chemical stability，and low thermal expansion coefficient. However，their widespread application is hindered by the high melting point of Y₂O₃，which necessitates energy-intensive sintering processes at temperatures often exceeding 1 800 ℃ to achieve full densification. Conventional approaches to lower the sintering temperature typically rely on either complex，time-consuming synthesis of ultra-high-purity，nano-sized powders or on expensive advanced sintering techniques like hot isostatic pressing （HIP） or spark plasma sintering （SPS），limiting their scalability and cost-effectiveness. In this study，we report a simple，scalable，and low-cost strategy to dramatically enhance the sinterability of commercial Y₂O₃ powder through an oxalic acid liquid-phase pretreatment，enabling its low-temperature densification via vacuum pressureless sintering，which is a method that is both industrially favored and economically viable.The method involves treating ball-milled commercial Y₂O₃ powder with a 1.2 mol/L oxalic acid solution，followed by filtration，washing，and a final calcination at 700 ℃. This treatment is shown to have a profound，multi-faceted activation effect. It not only efficiently removes surface-adsorbed impurities and carbonates，as confirmed by FT-IR analysis，but also refines the average particle size from 1.0~1.3 μm to approximately 300 nm. Crucially，the chelation between Y³⁺ and C₂O₄^2- leads to the in-situ formation of a yttrium oxalate precursor，which upon decomposition generates a substantial population of 30~50 nm Y₂O₃ nanoparticles. These nanoscale particles act as highly reactive sintering seeds，significantly boosting the overall sintering activity of the powder.The impact of this pretreatment on the sintering behavior and optical quality of Y₂O₃ ceramics was systematically investigated. For 2.0%（atomic fraction） ZrO₂-doped Y₂O₃，the oxalic acid treatment reduced the densification temperature by approximately 100 ℃. Near-full densification with a uniform，fine-grained microstructure was achieved at just 1 700 ℃ for 5 h under vacuum，a temperature at which untreated samples remained porous and opaque. This low-temperature densification is attributed to the combined effects of improved powder dispersion，and the presence of the nano-sized Y₂O₃ particles that enhance grain boundary diffusion. The superior sintering activity and microstructural uniformity directly translated into outstanding optical performance. Sintered at 1 750 ℃，the treated Y₂O₃ ceramics exhibit a maximum in-line transmittance of 75.8% at 600 nm，representing a significant advancement over untreated samples which showed no transmittance at this wavelength under identical conditions.In conclusion，this work introduces a highly effective powder activation strategy that bridges the gap between low-cost commercial precursors and the demanding requirements of high-performance transparent ceramics. By demonstrating that a simple oxalic acid wash can match the sintering efficacy of complex powder synthesis routes，this research provides a new paradigm for the low-temperature，cost-effective fabrication of high-melting-point oxide ceramics.

First-Principles Calculation Study on Metal-Doped β -Ga₂O₃ for Photocatalysis

ZHANG Ye, YANG Fengdie, LIU Lanxuan, ZHANG Qimiao, YAO Mingyuan, WANG Chaofan, MIAO Ruixia, HOU Yinlong

2026, 55(6):  940-948.  doi:10.16553/j.cnki.issn1000-985x.xb2026.0024

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Aiming at the problem of narrow response spectrum of β-Ga₂O₃ in photocatalysis caused by high carrier recombination rate and wide band gap，the influence mechanisms of metal Zn，Cd，and Hg doping on the electronic structure，optical properties，and catalytic stability of β-Ga₂O₃ were investigated via first-principles calculation in this study. The results show that all three metal-doped systems all meet the energy level matching conditions for photocatalytic water splitting. Among them，the electron-hole relative effective mass ratio （m_{\mathrm{e}}^{\mathrm{*}}/m_{\mathrm{h}}^{\mathrm{*}}） of the Zn-doped system is higher than those of the Cd- and Hg-doped systems，which is more conducive to the spatial separation and migration of photogenerated carriers. Formation energy calculations show that Zn doping preferentially occupies Ga（1） lattice sites under oxygen-rich conditions，and its formation energy is much lower than those of Cd- and Hg-doped systems，indicating that Zn-doped β-Ga₂O₃ has the optimal structural stability. Optical absorption spectrum analysis shows that the optical absorption capacity of the material presents anisotropy，and the optical absorption coefficient along the ［001］ crystal direction is significantly higher than those along the ［100］ and ［010］ directions. Zn，Cd，and Hg doping greatly improve the optical absorption capacity of β-Ga₂O₃ in the infrared region. In summary，among the three metal doping，Zn doping can be used as the preferred impurity. This result provides a theoretical reference for the design of high-efficiency photocatalysts.

Formation Mechanism of Vacancies on M₂SnC (M=Ti, V, Hf, Zr) and Its Effect on Mechanical Properties

SHEN Yunan, PING Yutong, HUANG Miaoyan, CHEN Yue, LIU Yushuang

2026, 55(6):  949-955.  doi:10.16553/j.cnki.issn1000-985x.2026.0036

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To address the unresolved issues regarding the formation of Sn vacancies in M₂SnC （M=Ti，V，Hf，Zr） and its influence on mechanical properties，this study systematically employed the first-principles calculation method based on density functional theory to investigate the formation energies，structural stability of Sn vacancies，and their effects on mechanical properties. The results indicate that the formation energies of Sn vacancies in M₂SnC are lower than those of M and C vacancies，suggesting that Sn vacancies are more readily formed. Among the compounds，V₂SnC exhibits the lowest formation energy for Sn vacancies，while Zr₂SnC shows the highest formation energy for Sn vacancies. The formation enthalpy calculation and elastic constant analysis reveal that the structures remain thermodynamic and mechanical stablility after the introduction of Sn vacancies. Mechanical property analysis demonstrates that the influence of Sn vacancies varies significantly across different M₂SnC phases. After the introduction of Sn vacancies，the bulk modulus，shear modulus and elastic modulus of Ti₂SnC，Hf₂SnC and Zr₂SnC decrease，whereas the shear modulus and elastic modulus of V₂SnC increase，whose enhancement may be attributed to vacancy-induced local bond reconstruction. MAX phases are a family of ternary layered carbide/nitride ceramic materials.The research results provide a theoretical foundation for the construction and modulation of A-site vacancies in MAX phases.

Effect of Sr_0.7M_0.2TiO₃(M=Bi, Sm, La, Gd) Doping on Properties of (Bi_0.5Na_0.5)_0.94Ba_0.06TiO₃ Ceramic Energy-Storage Materials

LIU Zhaolin, SHAO Hui, LI Jianping

2026, 55(6):  956-965.  doi:10.16553/j.cnki.issn1000-985x.xb2026.0015

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In this paper，ceramic energy-storage materials of 0.95（Bi_0.5Na_0.5）_0.94Ba_0.06TiO₃-0.05Sr_0.7M_0.2TiO₃ （M=Bi，Sm，La，Gd，BNBT-SMT） were prepared by the solid-state sintering method，and their crystal structure，dielectric temperature spectra，ferroelectric properties，and energy-storage properties were investigated. XRD results show that all ceramic samples exhibit a single perovskite structure after sintering at 1 125 ℃. The dielectric temperature spectra indicate that all ceramic samples display typical characteristics of relaxor ferroelectrics. With Sr_0.7M_0.2TiO₃ doping，shape of the hysteresis loop curves of samples exhibit an obvious evolution trend，and its shape gradually changes from the “wide fat type” characteristic with wider and larger saturation polarization value to the “slender type” with narrower，smaller remanent polarization intensity and relatively lower coercive field strength. Meanwhile，the maximum polarization intensity （P_max） is significantly enhanced，thereby improving the energy-storage properties of the materials. When M=Bi and the applied electric field is 4 kV/mm，the recoverable energy-storage density reaches the optimal value of W_rec=0.29 J·cm^-3，and the corresponding energy-storage efficiency of η= 51.4%.

Preparation and Properties of TiO₂/CdS/ α -Fe₂O₃ Heterostructured Photoanodes

SU Shi, WANG Lixing, CHE Zhiyuan, ZHANG Lina, MA Jinwen

2026, 55(6):  966-971.  doi:10.16553/j.cnki.issn1000-985x.2026.0010

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To address the issues of a narrow light absorption range and a high recombination rate of photogenerated carriers in TiO₂-based photoanodes，this study successfully prepared TiO₂/CdS/α-Fe₂O₃ ternary heterojunction thin films using a combined process that integrated the hydrothermal method with the successive ionic layer adsorption and reaction method. The crystal phase，microstructure，optical properties，and photoelectrochemical characteristics of the prepared photoanodes were systematically characterized and analyzed through X-ray diffraction，scanning electron microscopy，ultraviolet-visible absorption spectroscopy，and a three-electrode photoelectrochemical testing system. The results demonstrate that CdS nanoparticles are uniformly anchored on the surface of TiO₂ nanosheets，while α-Fe₂O₃ grows densely on the surface of the composite system in the form of regular nanospikes. The optical absorption edge of the TiO₂/CdS/α-Fe₂O₃ ternary heterojunction film exhibits a red shift to 595 nm，which is significantly broader than those of pure TiO₂ and TiO₂/CdS binary composite films. Correspondingly，the maximum photocurrent density reaches 2.37 mA/cm²，approximately 24 times and 1.9 times that of pure TiO₂ and TiO₂/CdS，respectively. The enhanced performance of the TiO₂/CdS/α-Fe₂O₃ photoanode is attributed to the broadening of the light-response range of TiO₂ by CdS and α-Fe₂O₃，as well as the formation of a stepwise energy-level structure among the three components，which effectively promotes the separation and transport of photogenerated electron-hole pairs and reduces carrier recombination. This study provides a feasible strategy and experimental basis for the structural optimization and performance improvement of TiO₂-based photoanodes.

Effect of Concentration Regulation on Electrochemical Properties of NiCo₂S₄/Graphene Aerogel Composites

LI Boxia, WANG Xiaomin

2026, 55(6):  972-980.  doi:10.16553/j.cnki.issn1000-985x.xb2026.0012

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In this study，the nickel cobalt sulfide/graphene aerogel （NiCo₂S₄/GA） composites with a self-supporting structure were successfully prepared by a hydrothermal method through adjusting the ratio of raw materials such as nickel cobalt salts. The structure，micromorphology and electrochemical properties of the composites were comprehensively investigated by X-ray diffraction （XRD），scanning electron microscopy （SEM） and other characterization techniques，together with an electrochemical workstation. The results show that in the sample （NiCo₂S₄/GA-1∶1） with a reactant molar concentration ratio of 1∶1，NiCo₂S₄ nanoparticles are loaded uniformly with high density without agglomeration，the area-specific resistance is 1.99 Ω·cm². The capacitance retention rate reaches 70.1% after 1 500 cycles at a current density of 2 A·g^-1. Electrochemical kinetic analysis reveals that the NiCo₂S₄/GA-1∶1 composite electrode exhibits pseudocapacitive behavior dominated by diffusion effects. This phenomenon is mainly attributed to the porous structure of graphene aerogel，as well as the optimization of graphene nanosheets on the capacitive performance of NiCo₂S₄ during the energy storage process，which thus endows the composite with a distinct synergistic effect. Thus，NiCo₂S₄/GA-1∶1 composite has great application potential as electrode material for supercapacitors.