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Tuning of the Optical Properties of the Transparent Conducting Oxide SrVO <sub/>3</sub> by Electronic Correlations
摘要： The vanadate SrVO3 is a transparent conductor perovskite with optical and electrical properties competing with those of the most-used indium tin oxide material. Although its charge density is comparable to that of metals, SrVO3 shows a plasma frequency below the visible range due to strong electronic correlations characterizing the electronic transport in this material and enhancing the effective mass. Therefore, the well-known interplay between the structure and the electronic properties of strongly correlated systems can be used in such transparent conductor to tune the optical properties, as the plasma frequency also depends on the effective mass. In this study, SrVO3 films are grown by pulsed laser deposition onto different lattice mismatched perovskite substrates such as SrTiO3, LaAlO3, and (LaAlO3)0.3(Sr2TaAlO6)0.7 at different growth temperatures. The structural, electronic, and optical properties are analyzed, illustrating the influence of the strain on the structure of the films and on a shift of the plasma frequency. The electronic correlations in this new group of transparent conducting oxides can be therefore used as a supplementary lever for the tuning of the functional properties.
关键词： transparent conducting oxides,vanadates,thin films,correlated materials,epitaxy
更新于2025-10-22 19:40:53
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Colloidal Rare Earth Vanadate Single Crystalline Particles as Ratiometric Luminescent Thermometers
摘要： Thulium/ytterbium-doped yttrium vanadate particles provide ratiometric thermal response as both colloids and powders via downshift or upconversion emissions. Here, we synthesized yttrium vanadates by controlled colloidal conversion of hydroxycarbonate precursors. A protected annealing process yielded single crystalline and readily dispersible particles that were manipulated individually by optical tweezers in water. Because individual particles displayed detectable emissions, this system has potential applications as a single-particle luminescent temperature sensor. Excitation on Yb3+ sensitizers (λexc=980 nm) or at vanadate groups (λexc=300 nm) resulted in Tm3+ emissions that effectively correlated with the temperature of the sample from 288 to 473 K with high relative thermal sensitivity (0.8-2.2% K-1), one of the highest reported for vanadate nanocrystals so far. Different pairs of Tm3+ transitions afford a ratiometric thermal response, which fitted common sensing requirements such as large [3F2,3→3H6 (λ=700 nm)/1G4→3H6 (λ=475 nm)] or small [3F2,3→3H6 (λ=700 nm)/1G4→3F4 (λ=650 nm)] spectral gaps, and emission wavelengths at the first near infrared biological window [3F2,3→3F4 (λ=700 nm)/3H4→3H6 (λ=800 nm)]. Our findings open new perspectives for the use of luminescent nanothermometers with controllable spatial localization, which is a remarkably interesting prospect to investigate microscopically-localized events related to changes in temperature.
关键词： Luminescence,Thermometry,Nanoparticles,Thermal Sensors,Vanadates,Optical Trapping,Rare Earth
更新于2025-09-23 15:23:52
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Fabricating nano-sized BiVO <sub/>4</sub> /InVO <sub/>4</sub> /g-C <sub/>3</sub> N <sub/>4</sub> photocatalysts for efficient degradation of Acid Blue 92 azo dye
摘要： BiVO4/InVO4 and BiVO4/InVO4/g-C3N4 were prepared by hydrothermal and ultrasonic-assisted hydrothermal methods respectively. All prepared samples were characterised by X-ray diffraction, scanning electron microscopy and UV-Vis diffuse reflectance spectroscopy. The photocatalytic activity of the prepared catalysts was determined by degradation of Acid Blue 92 (AB92) under visible light. The rate constant and efficiency of AB92 degradation over BiVO4/InVO4/g-C3N4 was higher than that over BiVO4/InVO4 which indicates better photocatalytic activity of BiVO4/InVO4/g-C3N4. This enhancement can be attributed to the suitable dispersion of BiVO4 and InVO4 particles on the g-C3N4 surface. Furthermore, the conduction band and valence band edge potentials of InVO4, BiVO4 and g-C3N4 extend the life-time of electron–hole pairs which is beneficial for the improvement of photocatalytic efficiency.
关键词： ternary composites,photocatalysis,dye degradation,materials characterisation,g-C3N4,vanadates
更新于2025-09-23 15:22:29
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Electron Diffusion Length and Charge Separation Efficiency in Nanostructured Ternary Metal Vanadate Photoelectrodes
摘要： Ternary metal vanadates have recently emerged as promising photoelectrode materials for sunlight-driven water splitting. Here, we show that highly active nanostructured BiVO4 films can be deposited onto fluorine-doped tin oxide (FTO) substrates by a facile sequential dipping method known as successive ionic layer adsorption and reaction (SILAR). After annealing and deposition of a cobalt phosphate (Co-Pi) co-catalyst, the photoelectrodes produce anodic photocurrents (under 100 mW cm-2 broadband illumination, 1.23 V vs. RHE) in pH 7 phosphate buffer that are on par with the highest reported in the literature for similar materials. To gain insight into the reason for the good performance of the deposited films, and to identify factors limiting their performance, incident photon-to-electron conversion efficiency spectra have been analyzed using a simple diffusion–reaction model to quantify the electron diffusion length (Ln; the average distance travelled before recombination) and charge separation efficiency (ηsep) in the films. The results indicate that ηsep approaches unity at sufficiently positive applied potential but the photocurrent is limited by significant charge collection losses due to a short Ln relative to the film thickness. The Co-Pi catalyst is found to improve ηsep at low potentials as well as increase Ln at all potentials studied. These findings help to clarify the role of the Co-Pi co-catalyst and show that there could be room for improvement of BiVO4 photoanodes deposited by SILAR if Ln can be increased.
关键词： charge separation efficiency,ternary metal vanadates,SILAR,electron diffusion length
更新于2025-09-23 15:22:29
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A Novel Highly Efficient Hosta??Sensitized Red Emitting (Ba <sub/>2</sub> YV <sub/>3</sub> O <sub/>11</sub> a??:a??Eu <sup>3+</sup> ) Phosphor for Hybrid White LEDs
摘要： The present investigation focused on the sequence of Eu3 + activated red-emitting vanadate phosphor for the high performance white LEDs. The blue emitting host lattice (Ba2YV3O11) and red emitting Ba2YV3O11 : Eu3 + phosphors were synthesized by the conventional solid-state method and studied their optical properties in details. The host lattice and Eu3 + activated red phosphors were crystallized in the monoclinic crystal system. The Ba2YV3O11 emission was found in the bluish-green region (444 and 512 nm, which corresponds to the 3T2!1A1 and 3T1!1A1 transitions), and the Eu3 + activated phosphors (Ba2Y1-xEuxV3O11, x = 0-1, insteps of 0.1) display intense red emission at 618 nm due to the 5D0!7F2 electric dipole (ED) transition. The concentration quenching was observed at x = 0.6, the detailed energy transfer mechanism was also explored. Thermal stability of the Ba2Y0.4Eu0.6V3O11 red phosphor retains the ～ 60 % emission intensity at 423 K, and the internal quantum efficiency (IQE) was found to be 30 %. The red and white LEDs were fabricated by using the synthesized red phosphor with the combination of near UV LED (n-UV), the white LED showed white emission with CIE is x = 0.359; y = 0.395; higher CRI (89) and low CCT (4693 K) values. These results prescribe that the presently synthesized phosphor can act as a suitable red-emitting component in hybrid white LEDs.
关键词： Vanadates,High CRI,Charge transfer,White LED,IQE
更新于2025-09-23 15:21:01
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BIFEVOX Composites: Manufacture and Characterization
摘要： Design of composites is a way to improve the quality of solid electrolytes. By mechanically mixing and annealing substituted bismuth vanadate with nanosized aluminum, bismuth, and zirconium binary oxides, we obtained heterogeneous materials Bi4V1.7Fe0.3O11 – δ/xAl2O3, Bi4V1.7Fe0.3O11 – δ/xBi2O3, and Bi4V1.7Fe0.3O11 – δ/xYSZ. The investigation tools were X-ray powder diffraction and electron microscopy with energy-dispersive microanalysis. The composition of materials was studied, the non-interaction of components was elucidated in the aluminum oxide and zirconium oxide composite series, and a nonuniform distribution of nanopowder particles across the surfaces and cleaves of sinters was discovered. The bismuth atoms from bismuth oxide were shown to be capable of incorporating into the Bi4Fe0.3V1.7O11 – δ structure. The charge transport characteristics of the materials were studied by impedance spectroscopy. No changes were observed in logσ–103/T trends in composites with various binary oxides and various oxide contents. An increase in binary oxide concentration was shown to give rise to an insignificant decay in electrical conductivity.
关键词： composite materials,bismuth vanadates,impedance spectroscopy,bismuth oxide,oxygen-ion conductors
更新于2025-09-10 09:29:36
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Tunable emission of LiCa3MgV3O12:Bi3+ via energy transfer and changing excitation wavelength
摘要： LiCa3MgV3O12:Bi3+ phosphor is successfully synthesized by the high-temperature solid-state reaction method in air. The crystal structures and luminescence properties are investigated. Excitation/emission bands of LiCa3MgV3O12:Bi3+ phosphor show red-shift with increasing the monitored/excitation wavelengths from short to long. The doping of Bi3+ ion can result in the host LiCa3MgV3O12 lattice distortion and the energy transfer to Bi3+. The tunable emission of LiCa3MgV3O12:Bi3+ phosphor from blue-green to yellow can be observed with increasing Bi3+ concentration from 0 to 8 mol%. The chromaticity coordinates of LiCa(3-x)MgV3O12:xBi3+ phosphors can change from (0.2393, 0.3260) to (0.4358, 0.4472) with increasing Bi3+ concentration from 0 to 8 mol%. The existence of VO4 3? → Bi3+ ET in LiCa3MgV3O12:Bi3+ phosphor is indicated by the luminescence properties. The luminous mechanism of LiCa3MgV3O12:Bi3+ phosphor is explained by the con?gurational coordinate diagrams of VO4 3? and Bi3+. The experimental results are helpful for the luminescence property researches of other Bi3+-doped luminescence materials.
关键词： Energy transfer,Tunable emission,LiCa3MgV3O12: Bi3+ ions,Vanadates
更新于2025-09-10 09:29:36