YVO4 Research Articles

Thermal history forensics using the emission intensity ratio of YVO4:Eu3+ phosphor

We demonstrate the thermal history forensic measurements founded on the emission intensity ratio of Eu3+-doped yttrium vanadate. An increase in phosphor’s crystallite size with annealing temperature is observed, causing a significant and permanent increase in the emission intensity and symmetry ratio (ratio of Eu3+ 5D0 → 7F1 and 5D0 → 7F2 emissions). This ratio is used as a forensic indicator of the maximal temperature to which phosphor was exposed. Additionally, we demonstrated that irreversible change in the symmetry ratio after exposure to high temperatures is insensitive to the exposure time. Finally, it is shown that thermal history readings can be performed at any temperature. The applicative potential of the proposed approach was confirmed in the proof-of-concept experiment on a steel plate covered with phosphor and exposed to high temperatures.

Superparamagnetic and light-emitting bifunctional nanocomposites of iron oxide and erbium or thulium doped yttrium orthovanadate

Advances in biomedical research have increased interest in obtaining and studying new bifunctional materials for use in theragnostic. Here we describe in detail the preparation of new magnetic-fluorescent bifunctional (Y0.9Ln0.1VO4/Fe3O4)@SiO2 and [(Y0.9Ln0.1VO4 @SiO2)/Fe3O4)@SiO2] nanocomposites with Ln = Er or Tm. In addition, their magnetic and optical properties were carefully analyzed. The influence of Fe3O4 content and the silica shell thickness on the fluorescent emission in the VIS-NIR region of Y0.9Ln0.1VO4 cores was evaluated as well as their use as display systems with the possibility of directing them by means of external magnetic fields. Samples were prepared using wet chemistry methods involving low temperatures and short reaction times. Y0.9Ln0.1VO4 samples that are not easily oxidizable were prepared by a hydrothermal method, while Fe3O4 sample was synthesized by a coprecipitation process in which the mixture of precursors was treated at very low temperature to avoid oxidation. The powder amalgamation of both Y0.9Ln0.1VO4 and Fe3O4 samples was possible due to the silica polymeric network synthetized by a modified Stöber method. The purity of all samples was ensured by XRD and FTIR techniques. Diffraction profiles of Y0.9Ln0.1VO4 samples show diffraction maxima that can be indexed to a tetragonal symmetry of space group I41/amd, compatible with the zircon structure-type of YVO4 host. All reflections present in the diffraction profile of Fe3O4 sample can be indexed to a cubic symmetry of space group Fd3̅m, characteristic of an inverse spinel structure-type. The amorphous silica incorporation on the samples was also evaluated by TEM images. Studies of the magnetic behavior and luminescent emission intensity of the investigated samples showed their dependence on both, the silica coating thickness, and the contact or not between the luminescent samples and the magnetic powder.

Yttrium orthovanadates phosphors as up-conversion luminescent markers for gunshot residue identification

In this work, yttrium orthovanadate phosphors doped with Er3+ and Yb3+ (YVO4: Er3+, Yb3+) were synthetized by the combustion method. After a post-synthesis heat treatment (1100 °C for 6 h), samples were highly crystalline, with only the tetragonal zircon phase remaining. Additionally, all samples presented promising down and up conversion properties, exhibiting a strong green luminescence when excited by either UV or IR radiation. The up-conversion process involved the absorption of two-photons, with the intensity of the Er3+ transitions (2H11/2–4I15/2, 4S3/2–4I15/2 and 4F9/2–4I15/2) heightened with the Yb3+ content. The co-doped orthovanadate samples were introduced into 9 mm non-toxic ammunition (NTA) for evaluation as luminescent markers for gunshot residues (GSR). After shots with marked ammunition were fired, these phosphors enabled the visual detection of luminescent GSR (LGSR) on the shooter, firearm and firing place, facilitating an analysis of the simulated crime scene. These residues also presented a chemical signature that enabled their identification as LGSR. Besides, the down and up conversion properties observed in the residues provide an additional security feature for the unequivocal characterization of the LGSR.

Rectangular Beam Pumped Raman Microchip Laser for Generating Multiwavelength High‐Order Hermite–Gaussian Lasers and Vortex Lasers

AbstractHigh‐order Hermite–Gaussian (HG) lasers oscillating at multiple wavelengths are extensively needed for generating vortex lasers carrying orbital angular momentum (OAM), which have wide applications on optical communication, high capacity storage, and high resolution imaging. Off‐axis pumping or off‐axis resonator has been used to generate high‐order HG0,n lasers, however, low optical efficiency limits practical applications of these lasers. Here, direct generation of multiple wavelength high‐order HG0,n lasers in a rectangular beam pumped Raman microchip laser constructed with Yb3+:Y3Al5O12 (Yb:YAG) and yttrium vanadate (YVO4) crystals is demonstrated. The order n of HG0,n mode lasers can be tuned from 1 to 9. HG0,n (n > 3) mode Raman lasers oscillate at multiple wavelengths and shift to longer wavelength with n. The output power is 137 mW for multiwavelength HG0,9 mode Raman laser when the input pump power is 2.7 W. The optical conversion efficiency is as high as 5.1%. Excellent beam quality with My2 close to theoretical values (My2 = 2n+1) for high‐order HG0,n lasers has been achieved. Topological charge tunable Laguerre–Gaussian (LG) vortex lasers with high beam quality are generated from HG0,n mode lasers with an astigmatic mode converter. This work demonstrates that rectangular beam pumping is an effective method for developing efficient multiwavelength high‐order HG0,n mode Raman lasers.

A nanotheranostic agent based on Nd3+-doped YVO4 with blood-brain-barrier permeability for NIR-II fluorescence imaging/magnetic resonance imaging and boosted sonodynamic therapy of orthotopic glioma

The specific diagnosis and treatment of gliomas is a primary challenge in clinic due to their high invasiveness and blood-brain barrier (BBB) obstruction. It is highly desirable to find a multifunctional agent with good BBB penetration for precise theranostics. Herein, we design and construct a core-shell structured nanotheranostic agent (YVO4:Nd3+-HMME@MnO2-LF, marked as YHM) with YVO4:Nd3+ particles as the core and MnO2 nanosheets as the shell. Sonosensitizer hematoporphyrinmonomethyl ether (HMME) and lactoferrin (LF) were further loaded and modified on the surface, giving it a good ability to cross the BBB, near-infrared fluorescence imaging in the second window (NIR-II)/magnetic resonance imaging (MRI) bimodality, and highly efficient sonodynamic therapy (SDT) of orthotopic gliomas. The YVO4:Nd3+ (25%) core exhibited good NIR-II fluorescence properties, enabling YHM to act as promising probes for NIR-II fluorescence imaging of vessels and orthotopic gliomas. MnO2 shell can not only provide O2 in the tumor microenvironments (TME) to significantly improve the healing efficacy of SDT, but also release Mn2+ ions to achieve T1-weight MRI in situ. Non-invasive SDT can effectively restrain tumor growth. This work not only demonstrates that multifunctional YHM is promising for diagnosis and treatment of orthotopic glioma, but also provides insights into exploring the theranostic agents based on rare earth-doped yttrium vanadate nanoparticles.

Use of Nd:YVO4 laser, photodynamic therapy, sulfuric acid and sand blasting on improving bond integrity of PEEK to resin cement with adhesive

AimThe present study aimed to inspect and compare several PEEK surface treatments modifications using Photodynamic therapy (PDT), Neodymium-doped yttrium orthovanadate (Nd:YVO4) laser, Sulphuric acid (H₂SO₄), and sandblasting (SB) when bonded to composite resin via an adhesive system Material and methodsOne hundred disk-shaped PEEK specimens were prepared by CAD-CAM milling and randomly distributed into five groups based on surface treatment methods: group1: Control (no treatment), group 2: PDT, group 3: Nd:YVO4 laser, group 4: H2SO4 and group 5 sandblasting. Later bonding was pursued using resin cement with an adhesive system. Measurements of surface roughness employing a surface profilometer, water contact angle by the static drop method, SBS by universal Testing machine, and failure modes of de-bonded PEEK specimens by Stereomicroscope were attained. Execution of statistical analysis was performed by two-way analysis of variance ANOVA and Tukey's post hoc test (p>0.05). The Shapiro–Wilk normality test and Bartlett's test for homoscedasticity were also performed. ResultsThe highest SBS was exhibited by Nd:YVO4 laser (16.33 ± 0.71 MPa) and the lowest SBS was observed in the control group (9.4 ± 1.02). However, PEEK specimen luted with resin cement treated with PDT (16.21 ± 0.14 MPa) and H2SO4 (15.23 ± 0.63 MPa) displayed a comparable SBS to Nd:YVO4 laser (p>0.05). The results of Ra exhibited that PEEK material when exposed to Nd:YVO4 laser (15.252 ± 1.581 μm) unveiled the highest Ra. Nd:YVO4 laser (131.25 ± 2.9 μm) and PDT (130.24 ± 3.7 μm) showed comparable WCA values (p>0.05).Adhesive failure was dominant. ConclusionPEEK surface treated with photodynamic therapy and Neodymium-doped yttrium orthovanadate laser and bonded to composite resin via an adhesive system significantly improved shear bond strength, surface roughness, and water contact angle.

Nuclear spin-wave quantum register for a solid-state qubit.

Solid-state nuclear spins surrounding individual, optically addressable qubits1,2 are a crucial resource for quantum networks3-6, computation7-11 and simulation12. Although hosts with sparse nuclear spin baths are typically chosen to mitigate qubit decoherence13, developing coherent quantum systems in nuclear-spin-rich hosts enables exploration of a much broader range of materials for quantum information applications. The collective modes of these dense nuclear spin ensembles provide a natural basis for quantum storage14; however, using them as a resource for single-spin qubits has thus far remained elusive. Here, by using a highly coherent, optically addressed 171Yb3+ qubit doped into a nuclear-spin-rich yttrium orthovanadate crystal15, we develop a robust quantum control protocol to manipulate the multi-level nuclear spin states of neighbouring 51V5+ lattice ions. Via a dynamically engineered spin-exchange interaction, we polarize this nuclear spin ensemble, generate collective spin excitations, and subsequently use them toimplement a quantum memory. We additionally demonstrate preparation and measurement of maximally entangled 171Yb-51V Bell states. Unlike conventional, disordered nuclear-spin-based quantum memories16-24, our platform is deterministic and reproducible, ensuring identical quantum registers for all 171Yb3+ qubits. Our approach provides a framework for utilizing the complex structure of dense nuclear spin baths, paving the way towards building large-scale quantum networks using single rare-earth ion qubits15,25-28.

Broadband Petal‐Like Raman Laser

AbstractHigh‐order Laguerre‐Gaussian (LG0,n) petal‐like lasers are extremely important for manipulating microparticles, creating 3D optical trapping structures, and free space optical communication. However, it is difficult to expand the wavelength of LG0,n petal‐like lasers owing to the narrow fluorescence spectrum of laser gain media. Here, a Raman laser constructed with a Yb3+:Y3Al5O12 (Yb:YAG) crystal and a yttrium vanadate (YVO4) is demonstrated for achieving a high‐order LG0,n petal‐like laser with broadband laser wavelength and high beam quality. High‐order LG0,n petal‐like lasers with n tunable from 3 to 11 are obtained. The LG0,11 petal‐like Raman laser oscillates from 1075.4 to 1088.7 nm with 44 longitudinal modes, and the bandwidth of the Raman laser is 13.3 nm. The output power of the LG0,11 petal‐like Raman laser is 126 mW with an optical efficiency of 1.5%. High‐order LG0,n petal‐like Raman lasers with tunable n provide flexible choices for potential applications in manipulating microparticles and biological molecules.

Enhanced Optical Properties of Yttrium Aluminum Garnet with the Yttrium Vanadate Impurity Phase

Enhanced Optical Properties of Yttrium Aluminum Garnet with the Yttrium Vanadate Impurity Phase

Antitumor activity of solamargine in mouse melanoma model: relevance to clinical safety

ABSTRACT Melanoma is the most aggressive type of skin cancer, and thus it is important to develop new drugs for its treatment. The present study aimed to examine the antitumor effects of solamargine a major alkaloid heteroside present in Solanum lycocarpum fruit. In addition solamargine was incorporated into nanoparticles (NP) of yttrium vanadate functionalized with 3-chloropropyltrimethoxysilane (YVO4:Eu3+:CPTES:SM) to determine antitumor activity. The anti-melanoma assessment was performed using a syngeneic mouse melanoma model B16F10 cell line. In addition, systemic toxicity, nephrotoxic, and genotoxic parameters were assessed. Solamargine, at doses of 5 or 10 mg/kg/day administered subcutaneously to male C57BL/6 mice for 5 days, decreased tumor size and frequency of mitoses in tumor tissue, indicative of a decrease in cell proliferation. Treatments with YVO4:Eu3+:CPTES:SM significantly reduced the number of mitoses in tumor tissue, associated with no change in tumor size. There were no apparent signs of systemic toxicity, nephrotoxicity, and genotoxicity initiated by treatments either with solamargine alone or plant alkaloid incorporated into NP. The animals treated with YVO4:Eu3+:CPTES:SM exhibited significant increase in spleen weight accompanied by no apparent histological changes in all tissues examined. In addition, animals treated with solamargine (10 mg/kg/day) and YVO4:Eu3+:CPTES:SM demonstrated significant reduction in hepatic DNA damage which was induced by tumor growth. Therefore, data suggest that solamargine may be considered a promising candidate in cancer therapy with no apparent toxic effects.

Surface optical phonon and multi – phonon transitions in YVO4:Eu3+ nanopowders

In this paper two methods of preparation of yttrium orthovanadate nanopowders were presented: Solid State Reaction (top – down approach) and Solution Combustion Synthesis (bottom – up approach). For starting structural characterization, X – Ray Powder Diffraction (XPRD) and Field Emission Scanning Electron Microscopy (FESEM) were used. We report the change in reflection spectra in europium doped YVO4 nanopowders with comparison to its bulk analog. In UV–Vis reflection spectra we consider the change in values of band gap in these structures, after resizing it from bulk to nanomaterial. In Far – Infrared (FIR) reflection spectra, we registered the existence of Surface Optical Phonon (SOP) and different multi – phonon processes which alter the reflection spectra of bulk YVO4. The influence of Eu ions is reflected through multi – phonon processes that occur and are connected with energy transfer from YVO4 lattice to Eu ions. All IR spectra were modeled using classical oscillator model with Drude part added which takes into account the free carrier contribution. Since our samples are distinctively inhomogeneous materials, we use Effective Medium theory in Maxwell Garnett approximation to model its effective dieletric function.

Effects of Insertion of Ag Mid-Layers on Laser Direct Ablation of Transparent Conductive ITO/Ag/ITO Multilayers: Role of Effective Absorption and Focusing of Photothermal Energy.

From the viewpoint of the device performance, the fabrication and patterning of oxide–metal–oxide (OMO) multilayers (MLs) as transparent conductive oxide electrodes with a high figure of merit have been extensively investigated for diverse optoelectronic and energy device applications, although the issues of their general concerns about possible shortcomings, such as a more complicated fabrication process with increasing cost, still remain. However, the underlying mechanism by which a thin metal mid-layer affects the overall performance of prepatterned OMO ML electrodes has not been fully elucidated. In this study, indium tin oxide (ITO)/silver (Ag)/ITO MLs are fabricated using an in-line sputtering method for different Ag thicknesses on glass substrates. Subsequently, a Q-switched diode-pumped neodymium-doped yttrium vanadate (Nd:YVO4, λ = 1064 nm) laser is employed for the direct ablation of the ITO/Ag/ITO ML films to pattern ITO/Ag/ITO ML electrodes. Analysis of the laser-patterned results indicate that the ITO/Ag/ITO ML films exhibit wider ablation widths and lower ablation thresholds than ITO single layer (SL) films. However, the dependence of Ag thickness on the laser patterning results of the ITO/Ag/ITO MLs is not observed, despite the difference in their absorption coefficients. The results show that the laser direct patterning of ITO/Ag/ITO MLs is primarily affected by rapid thermal heating, melting, and vaporization of the inserted Ag mid-layer, which has considerably higher thermal conductivity and absorption coefficients than the ITO layers. Simulation reveals the importance of the Ag mid-layer in the effective absorption and focusing of photothermal energy, thereby supporting the experimental observations. The laser-patterned ITO/Ag/ITO ML electrodes indicate a comparable optical transmittance, a higher electrical current density, and a lower resistance compared with the ITO SL electrode.

Well-Designed Construction of Yttrium Orthovanadate Confined on Graphitic Carbon Nitride Sheets: Electrochemical Investigation of Dimetridazole.

Antibiotics are the most important drugs for people and animals to fight bacterial illnesses. Overuse of antibiotics has had unintended consequences, such as antibiotic resistance and ecosystem eradication owing to toxic chemical discharge, which have a negative influence on the biome. Herein, we report the synthesis of a hollow ellipsoid-shaped yttrium vanadate/graphitic carbon nitride (YVO4@CN) nanocomposite by a hydrothermal approach followed by a sonochemical method for the effective detection of dimetridazole (DMZ). The synergic and coupling effect between both the phases offer non-linear cumulative ramifications which can positively enhance the individual properties of the materials under consideration. This positive hybrid effect increases the conductivity, shortens the ion-diffusion pathway, enhances the electron/ion transportation, and provides more active sites and electron-conducting channels. The accurate optimization of the experimental conditions proposes good electrocatalytic activity for the YVO4@CN catalyst, exhibiting a good response toward DMZ detection. It reveals an extensive linear concentration range (0.001-153.3 and 176.64-351.6 μM), a low detection limit (0.8 nM), higher sensitivity (4.98 μA μM-1 cm-2), appreciable selectivity, increased operational stability (2200 s), and good cycle stability (60 cycles). The electrochemical performance of YVO4@CN indicates its practical application in real-time sample analysis of several families of nitroimidazole drugs.

Synthesis of δ-Ta2O5 heteroepitaxial films on YVO4 (100) substrates

Hexagonal tantalum pentoxide (δ-Ta2O5) single-crystalline films were synthesized on Yttrium Vanadate (YVO4) (100) by metalorganic chemical vapor deposition (MOCVD) and post annealing process. The film annealed at 900 °C exhibited single crystal structure with the best crystalline quality. The heteroepitaxial relationship was determined as δ-Ta2O5 (0001)||YVO4 (100) with δ-Ta2O5 [1‾21‾0]||YVO4 [010] by the analysis of lattice structure. A diagrammatic sketch was proposed to illustrate the growth mechanism. For the best δ-Ta2O5 single-crystalline film, the band gap was estimated to be 4.33 eV and the average transmittance in the visible range exceeded 92%.

Vanadium and Melanoma: A Systematic Review

The application of metals in biological systems has been a rapidly growing branch of science. Vanadium has been investigated and reported as an anticancer agent. Melanoma is the most aggressive type of skin cancer, the incidence of which has been increasing annually worldwide. It is of paramount importance to identify novel pharmacological agents for melanoma treatment. Herein, a systematic review of publications including “Melanoma and Vanadium” was performed. Nine vanadium articles in several melanoma cells lines such as human A375, human CN-mel and murine B16F10, as well as in vivo studies, are described. Vanadium-based compounds with anticancer activity against melanoma include: (1) oxidovanadium(IV); (2) XMenes; (3) vanadium pentoxide, (4) oxidovanadium(IV) pyridinonate compounds; (5) vanadate; (6) polysaccharides vanadium(IV/V) complexes; (7) mixed-metal binuclear ruthenium(II)–vanadium(IV) complexes; (8) pyridoxal-based oxidovanadium(IV) complexes and (9) functionalized nanoparticles of yttrium vanadate doped with europium. Vanadium compounds and/or vanadium materials show potential anticancer activities that may be used as a useful approach to treat melanoma.

Manipulation of Polarizations with Crystalline Orientation for an Elliptically Polarized Passively Q‐Switched Raman Laser

AbstractPolarization control of dual‐wavelength high peak power Raman lasers based on passively Q‐switched technology and yttrium vanadate (YVO4) crystal are widely used for generating novel laser sources, terahertz wave, material processing, and manipulating microparticles. However, the Raman lasers are usually linear polarization. Here, elliptical polarizations with controllable ellipticity and azimuthal angle are manipulated by adjusting the crystalline orientation of a‐cut YVO4 crystal in a passively Q‐switched Raman laser constructed with a Cr4+,Nd3+:Y3Al5O12 (Cr,Nd:YAG) crystal and a a‐cut YVO4 crystal. The ellipticity of the elliptically polarized dual‐wavelength Raman laser varies in a sinusoid modulation as a‐cut YVO4 crystal rotates with respect to the major axis of the intracavity fundamental laser and increases with applied pump power. The azimuthal angle varies in the same speed as a‐cut YVO4 crystal rotates. Anisotropic behavior of sinusoidal modulation of output power, pulse energy, and peak power is observed as a‐cut YVO4 crystal rotates. There are four peaks and four troughs for ellipticity, output power, pulse energy, and peak power within a 360° rotation of a‐cut YVO4 crystal. This work provides a solid and simple method for developing elliptical polarization controllable dual‐wavelength passively Q‐switched Raman laser with high peak power for various potential applications.

Downshifting and Antireflective Thin Films for Solar Module Power Enhancement

Efforts to enhance the solar conversion efficiency have prevailed for decades. There is a growing interest in improving the spectral response of solar modules, especially in harvesting UV photons, which offer intense energy in a narrow wavelength range. To harvest UV photons and reduce reflection without interfering with the formulas and manufacturing process of solar cells, in this work, thin films that possess downshifting and antireflection capabilities were fabricated on the cover glass of multicrystalline Si solar cells. The thin films were composed of graded index layers of europium-doped yttrium orthovanadate (YVO4:Eu) and hollow silica nanoparticles (HSNPs). The design of the composite thin films was assisted by the FDTD mathematical model that simulated the refractive index and thickness of each layer to obtain the optimum transmittance. The cover glass with multifunctional thin films harvested more than 30 % of UV photons and enhanced the solar conversion efficiency by 4.12 % at normal incidence compared to the uncoated cover glass.

Colorimetric determination of hydrogen peroxide based on the robust peroxidase-like activities of flower-like YVO4 microstructures

In this study, yttrium vanadate (YVO4) flower-like microstructures assembled by quadrangular prisms (YVFPs) were prepared through a facile hydrothermal method, which were developed as a novel nanoenzyme to determine hydrogen peroxide (H2O2) for the first time. In the presence of H2O2, YVFPs exhibited a highly efficient peroxidase-like activity in catalyzing the oxidation the typical peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB). Colorless TMB would be turned into oxidized TMB with a visible blue color and UV–visible absorption peak at 652 nm. The catalytic reaction mechanism was proposed according to the kinetics experiments and active species capture tests, indicating that·O2- radicals played a key role in the peroxidase mimetic reaction. Besides, YVFPs showed a superior affinity to TMB compared with the natural enzyme horse radish peroxidase with a lower Km value. Taking advantage of the strong peroxidase-like activity of YVFPs, a simple, rapid, sensitive, and visual platform was successfully established for colorimetric detection of H2O2. The YVFPs-based colorimetric system possessed good selectivity, stability and reusability with a wider linear range from 0.5 μM to 50 μM and a lower detection limit as low as 0.126 μM towards H2O2 determination. Moreover, the feasibility of this convenient method was further validated by assaying residual H2O2 in milk and contact lens solutions. This work not only provides a novel artificial biomimetic catalyst with efficient catalytic abilities, but also opens up a new potential application field of YVO4 materials in clinical diagnosis, food safety and biomedicine.

Rational Confinement of Yttrium Vanadate within Three-Dimensional Graphene Aerogel: Electrochemical Analysis of Monoamine Neurotransmitter (Dopamine).

Real-time monitoring of neurotransmitter levels is of tremendous technological demand, which requires more sensitive and selective sensors over a dynamic concentration range. As a use case, we report yttrium vanadate within three-dimensional graphene aerogel (YVO/GA) as a novel electrocatalyst for detecting dopamine (DA). This synergy effect endows YVO/GA nanocomposite with good electrochemical behaviors for DA detection compared to other electrodes. Benefiting from tailorable properties, it provides a large specific surface area, rapid electron transfer, more active sites, good catalytic activity, synergic effect, and high conductivity. The essential analytical parameters were estimated from the calibration plot, such as a limit of detection (1.5 nM) and sensitivity (7.1 μA μM-1 cm-2) with the YVO/GA sensor probe electrochemical approach. The calibration curve was fitted with the correlation coefficient of 0.994 in the DA concentration range from 0.009 to 83 μM, which is denoted as the linear working range. We further demonstrate the proposed YVO/GA sensor's applicability to detect DA in human serum sample with an acceptable recovery range. Our results imply that the developed sensor could be applied to the early analysis of dementia, psychiatric, and neurodegenerative disorders.

Effect of calcination temperature on the microstructure and optical properties of monodispersed self-assembled yttrium orthovanadate microspheres

Monodispersed self-assembled Eu3+-doped yttrium orthovanadate (YVO4) microspheres have been prepared by a facile hydrothermal method using trisodium citrate (Na3C6H5O7) as surfactants and complexing agents. Then the as-prepared YVO4:Eu3+ microspheres were subjected to the calcination treatment at different temperatures. The phase structure, microstructure, and optical properties of these microspheres were characterized by X-ray diffraction (XRD) and refinement analysis with GSAS-II, scanning electron microscope (SEM), Fourier transform infrared (FT-IR) spectra, UV–Vis reflectance spectrum (UV–Vis RS), and photoluminescence (PL) spectra, respectively. XRD revealed a pure tetragonal phase structure without any impurities of the as-prepared YVO4:Eu3+ microspheres. SEM images indicated that the self-assembled YVO4:Eu3+ architectures were made up of microspheres with the average diameter of around 300 nm, which were self-assembled from tiny packed nanocrystallites with 24–30 nm in diameter. Remarkably, the microstructure of these self-assembled microspheres could be well preserved during the calcination process at high temperatures. Under UV light irradiation, YVO4:Eu3+ microspheres exhibited a bright red emission corresponding to the 5D1→7F1 and 5D0→7FJ (J = 1, 2, 3, 4) transitions of the Eu3+ ions. More importantly, compared with the as-prepared YVO4:Eu3+ microspheres, the microspheres after the calcined treatment showed superior optical properties, as indicated by higher emission intensity, longer decay lifetime, and higher quantum efficiency. The present results showed that the self-assembly synthesis combined with the calcination treatment could provide a facile route to optimize the luminescent properties of inorganic functional materials.