High-temperature Solid-phase Method Research Articles

Understanding Electrochemical Performance Enhancement with Quaternary NCMA Cathode Materials.

Ni-rich cathode materials show promise for use in lithium-ion batteries. However, a significant obstacle to their widespread adoption is the structural damage caused by microcracks. This research paper presents the synthesis of Ni-rich cathode materials, including LiNi0.8Co0.1Mn0.1O2 (referred to as NCM) and Li(Ni0.8Co0.1Mn0.1)0.98Al0.02O2 (referred to as NCMA), achieved through the high-temperature solid-phase method. Electrochemical (EC) testing results reveal the impressive EC performance of NCMA. NCMA exhibited a discharge capacity of 141.6 mAh g-1 and maintained a cycle retention rate of up to 74.92% after 300 cycles at a 1 C rate. In contrast, the NCM had a discharge capacity of 109.7 mAh g-1 and a cycle retention rate of 61.22%. Atomic force microscopy showed that the Derjaguin-Muller-Toporov (DMT) modulus value of NCMA exceeded that of NCM, signifying a greater mechanical strength of NCMA. Density functional theory calculations demonstrated that the addition of aluminum during the delithiation process led to the mitigation of anisotropic lattice changes and the stabilization of the NCMA structure. This improvement was attributed to the relatively stronger Al-O bonds compared to the Ni(Co, Mn)-O bonds, which reduced the formation of microcracks by enhancing NCMA's mechanical strength.

Synthesis of Bi3+ and Eu3+ co-doped Na4CaSi3O9 blue-red light tunable emission phosphors for inducing plant growth

Sunlight is an important factor in plant growth. In this regard, both blue and red lights provide significant contributions. Blue–red light dual-emission phosphors, which can be achieved by regulating energy transfer between two independent luminous centers, have recently been investigated extensively. In this study, Bi3+ and Eu3+ co-doped Na4CaSi3O9 (NCSO: Bi3+, Eu3+) phosphors are successfully synthesized via a high-temperature solid-phase method at approximately 900 °C for a few hours. X-ray powder diffraction is used to verify the crystal structure, phase purity, and structural refinement of the NCSO-based phosphors. Upon light excitation at 299 nm, the phosphors show blue–red dual emission. The blue emission (300–500 nm) may have originated from the 3P1 → 1S0 transition of Bi3+, whereas the red emission (575–725 nm) is attributable to the 5D0 → 7FJ (J = 1, 2, 3 and 4) transition of Eu3+ ions. Energy transfer from Bi3+ to Eu3+ is systematically investigated and the thermal stability of the phosphors is analyzed using temperature-dependent spectroscopy. The emission spectra of NCSO: Bi3+, Eu3+ are consistent with the absorption spectra of chlorophyll a, chlorophyll b, phytochrome PR, and phytochrome PFR. These results indicate that the obtained phosphors exhibit significant potential for inducing plant growth.

Achieving Luminescence of Sr3Ga1.98In0.02Ge4O14:0.03Cr3+ via [In3+] Substitution [Ga3+] and Its Application to NIR pc-LED in Non-Destructive Testing.

Cr3+-doped Sr3Ga2Ge4O14:0.03Cr3+ (SGGO:0.03Cr3+) phosphor was synthesized via a high-temperature solid-phase method. Considering the tunable structure of SGGO, Ga3+ ions in the matrix were substituted with In3+ ions at a certain concentration. The tuned phosphor produced a red-shifted emission spectrum, with its luminescence intensity at 423 K maintained at 63% of that at room temperature; moreover, the internal quantum efficiency increased to 65.60%, and the external quantum efficiency correspondingly increased to 21.94%. On this basis, SGIGO:0.03Cr3+ was encapsulated into a pc-LED, which was applied in non-destructive testing (NDT) experiments, successfully realizing the recognition of water and anhydrous ethanol, proving its potential application in the field of NDT.

Highly efficient visible emission of YPO4:Dy3+ via co-doping of Bi3+ ions

Dy3+ ions are an efficient activator for achieving near-UV-excited single-phase white light and blue LD-pumped yellow laser output. However, weak luminescence intensity is one of the main factors affecting its application. Herein, a series of Dy3+-doped and Dy3+/Bi3+ co-doped YPO4 phosphors were synthesized by high-temperature solid-phase method to enhance the luminescence of Dy3+ ions. The structure, morphology, and luminescence properties were studied using X-ray diffraction, scanning electron microscopy, and fluorescence spectroscopy. When excited at 353 nm and 450 nm, Dy3+ ions had three main emission peaks in the visible light range. When Bi3+/Dy3+ were co-doped, the emission intensity of the sample was significantly enhanced. The optimal doping concentration of Dy3+ was 4.0%. The energy transfer between Bi3+ and Dy3+ contribute to the enhancement of Dy3+ luminescence. The study indicates that Bi3+ co-doping can effectively enhance the visible light emission of Dy3+ ions.

Novel lithium ion-sieve spinning fiber composite of PVDF-HMO for lithium recovery from geothermal water

With the increasing application of the industrialization of lithium and its derivatives, there has been a surge of interest in recovering this resource from liquid sources. However, synthesizing adsorbents with industrial significance is still a significant challenge. Herein, the precursor Li1.6Mn1.6O4 of H1.6Mn1.6O4 powder absorbent with the highest theoretical adsorption capacity and the lowest Mn dissolution loss rate was first synthesized by hydrothermal or high-temperature solid phase method. The commercialized wet spinning apparatus, which has convenient operation and a simple process, was used to prepare PVDF/HMO spinning fiber to recover lithium resources from geothermal water. It has a large specific surface area of 31.45 m2 g−1 and a pore size of 9.04 nm, and the adsorption capacity was 14.95 mg g−1, with the distribution coefficient of Li+ being 1404.96 mL g−1. Furthermore, the equilibrium was reached within just 2 h at pH 12, and the elution time was just 1 h. Even after the fifth cycle, the adsorption capacity remained high at 14.21 mg g−1. These characteristics indicate that the new material has excellent application potential for lithium recovery from geothermal water.

Near-infrared luminescent properties and applications of Fe3+-doped YAG phosphors

This study employed the high-temperature solid-phase method to successfully synthesize a comprehensive range of Y3Al12O5: xFe3+ novel near-infrared (NIR) phosphors based on yttrium aluminum garnet material. The samples were subjected to characterization utilizing X-ray diffraction (XRD), scanning electron microscopy (SEM), absorption spectroscopy, first-principles calculations, excitation and emission spectroscopy, as well as temperature-dependent luminescence intensity analysis. Subsequently, the specimens were encapsulated within light-emitting diodes (LED) to facilitate their application in night vision and biometric sensing. The results revealed that all sintered samples were phase-pure, with particle sizes around 0.6 μm, exhibiting uniform and fully developed morphology. The absorption spectroscopy indicated a decrease in the bandgap with increasing Fe3+ doping concentration. The first-principles results revealed that the doping of Fe3+ introduces Fe-d orbitals, and their contribution to the conduction bands is nearly comparable to that of the d orbitals of the Y3+. The spectroscopic results indicated that the samples can be excited through charge transfer of O2− → Fe3+, leading to near-infrared emission at 784 nm with a full width at half maximum (FWHM) of 77 nm at 280 nm, and the FWHM is 73 nm under excitation at 411 nm. The thermal stability analysis revealed that as the temperature increased, there was no observed redshift or blueshift in the emission spectra. The encapsulated NIR LED allows clear visibility of blood vessels on the hand and cacti in a dark room environment. All the aforementioned results provide substantial evidence for the significant application potential of Y3Al12O5: xFe3+ NIR phosphors in biometric sensing and night vision.

Intense red upconversion luminescence and optical thermometry of a novel Yb3+/Er3+ co-doped Ba3Sc2WO9 phosphor

Yb3+/Er3+ co-doped Ba3Sc2WO9 strong red upconversion luminescent (UCL) phosphors have been achieved by high-temperature solid-phase method. Under 980 nm laser excitation, the phosphor emits strong red light at ∼667 nm and weak green light at ∼560 nm, with the intensity ratio of the red-green integrals up to 23.06. The band gap of the optimally doped Ba3Sc2WO9: 0.1 Yb3+, 0.03 Er3+ sample was calculated to be 3.14 eV. The main excitation process for the red light emission is the transition of Er3+ from the 4I13/2 energy state to the 4F9/2 energy state. In addition, the Yb3+/Er3+ doped Ba3Sc2WO9 red UCL phosphors have great potential for ambient temperature sensing in the temperature range 298–498 K. The Ba3Sc2WO9: 0.1 Yb3+, 0.03 Er3+ phosphor as a temperature sensor has a maximum sensitivity of 0.0096 K−1 at 498 K. This study provides a groundbreaking method for exploring new materials for strong red light upconversion emission.

A multi-mode optical thermometry based on the up-conversion La2MgGeO6: Er3+, Yb3+ phosphor

The up-conversion (UC) La2MgGeO6: Er3+, Yb3+ phosphors were prepared by a high-temperature solid-phase method. The structural phase and luminescence characteristics of the samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and photoluminescence spectra. The research systematically investigated a multi-mode optical thermometry based on fluorescence intensity ratios (FIR) of the thermal-coupled energy levels 2H11/2/4S3/2, non-thermal-coupled energy levels 4S3/2/4F9/2, and the fluorescence lifetime of the 4S3/2 state. Based on these methods, the maximum relative sensitivity reached 1.130%K−1, 0.623%K−1, and 2.914%K−1, respectively. According to the results, the manufactured samples have remarkable temperature measuring performance, which is characterized by a broad temperature measurement range, high sensitivity, and superior stability.

Ni2+-doped MgTa2O6 phosphors capable of near-infrared II and III emission under blue-light excitation

Presently, Ni2+-activated near-infrared (NIR) phosphors still have disadvantages such as relatively short emission wavelength and narrow half-peak width, mismatched excitation wavelength to that of commercially available high-efficiency blue chips. Here, Ni2+-doped tetragonal MgTa2O6 NIR phosphor was successfully prepared by high-temperature solid phase method. The matrix material provided an octahedral lattice for Ni2+ to replace Ta5+ in the [TaO6] octahedron of the crystal lattice. Under the excitation of 470 nm blue light, Ni2+ was excited through 3T2(F)→3A2(F) spin-allowed transition and emitted an ultra-broadband NIR light that was 1300–2000 nm in wavelength, peaked ∼ 1620 nm, covered the NIR-II and NIR-III regions, had a full width at half maximum reached 297 nm, and a PLQY of 25.62 %. The unique ultra-broadband and long wavelength NIR emission by this phosphor was derived from Ni2+ which is situated in a weak crystal field environment due to space asymmetric distortion caused by a high charge polarization surrounding the center of the [TaO6] octahedron in a MgTa2O6 matrix. A NIR pc-LED was constructed using Ni2+-doped near-infrared phosphors packaged with a commercial high-efficiency blue LED chip (@ 470 nm), and its application prospect was demonstrated by NIR night vision monitoring and nondestructive imaging of venous in human fingers.

Charge compensators achieve controlled self-reduction of Europium in BaMgP2O7

The exploitation of ecofriendly luminescent materials is crucial for advancing phosphor applications. Herein, Eu3+ self-reduction was performed using the energy-saving high-temperature solid-phase method in air environment. Achieving controllable self-reduction is challenging for high-valent rare-earth and transition metal ions. Therefore, we incorporate charge compensators, such as Li+/K+ to control the reaction and obtain hetero-valent Eu2+/Eu3+. Experimental results indicate that charge compensators can eliminate vacancies, suppress self-reduction, and affect luminescence properties. Moreover, a nonequivalent substitution mechanism about self-reduction using a charge compensation model is discussed here. Notably, Eu2+ shows a strong blue narrow-band emission peak at 410 nm with a full width at half maxima of 34 nm, overlapping well with that of chlorophyll. The phosphors are nontoxic and exhibit high contrast under ultraviolet light, which can be utilized for forensic science detection. The precisely controllable self-reduction of phosphors can contribute to the development of next-generation smart and green materials. Advanced applications of the phosphors for plant growth, fingerprint visualization, and screen printing are also explored.

Tunable broadband near-infrared photoluminescence of Mg2LaTaO6:Cr3+ phosphors for light-emitting diodes

Near-infrared phosphor-converted light-emitting diodes (NIR pc-LED) prepared with near-infrared (NIR) phosphors have potential applications in various aspects. In this paper, Cr3+-activated Mg2LaTaO6 (MLTO: Cr3+) phosphors were prepared by the conventional high-temperature solid-phase method. The structure, morphology, and photoluminescence (PL) spectra of MLTO: Cr3+ phosphor were investigated. There is broadband NIR emission and the emission peak is red-shifted with the increase of doping concentration. The crystal field strengths of the samples were calculated and the relationship between the emission peak positions of the samples and the crystal field strengths was investigated. In addition, the concentration quenching mechanism of the samples was discussed, which is mainly attributed to dipole-dipole interactions. The internal quantum efficiency (IQE) of the MLTO: 0.4 mol% Cr3+ sample was measured with an IQE value of 76.48 %. NIR pc-LED devices were fabricated by combining the prepared MLTO: Cr3+ phosphor and blue-emitting LED chips, which are capable of emitting NIR light.

Critical roles of multiphase coexistence in boosting piezo-catalytic activity of BaTiO3-based piezoelectric ceramics

Recently, piezocatalysis induced by perovskite ferroelectric ceramics has widely been favored as a possible fascinating strategy for water remediation due to its low cost, simplicity and feasibility. Herein, a strategy of three-ferroelectric-phase coexistence is proposed to boost the piezocatalytic performance of BaTiO3-based ceramics by introducing Ca(Sn0.5Zr0.5)O3 into BaTiO3. The piezocatalysts of (1-x)BaTiO3–xCa(Sn0.5Zr0.5)O3 ceramics were prepared by a high-temperature solid-phase method. The phase structure, microstructure, electrical properties and catalytic performance of ceramics were comprehensively studied. As x increases from 0 to 0.10, the ceramics undergo the phase evolution from single tetragonal phase to multiphase (coexistence of rhombic, orthorhombic, and tetragonal phases). It is found that the phase structure of the ceramics plays a critical role in enhancing the piezocatalytic activity. The pure BaTiO3 exhibits the tetragonal (T) phase with few spontaneous polarization directions and high polarization rotational energy barrier, resulting in poor catalytic performance and low piezoelectricity. With the coexistence of rhombic (R), orthorhombic (O) and tetragonal (T) phases, the ceramic with x = 0.1 exhibits the increased spontaneous polarization directions and low polarization rotational energy barrier, leading to excellent catalytic performance and high piezoelectricity. Especially, for the ceramics with x = 0.10, the degradation rates of rhodamine B (RhB), methylene blue (MB) and methyl orange (MO) under ultrasonication reach 97 %, 93 % and 73 %, respectively. In addition, the influencing factors of piezocatalytic degradation of RhB and the catalytic mechanism are investigated. This work proposes an environmentally friendly piezoelectric material for improving the water environment and a strategy for improving the catalytic activity of BaTiO3-based lead-free piezoelectric materials.

Emission enhancement of Eu3+ doped Ba2Zn(BO3)2 by adding charge compensators

Ba2Zn(BO3)2: xEu3+ (0.001≤x ≤ 0.30), Ba2Zn(BO3)2: 0.15Eu3+, 0.05R+ (RLi, Na, K) and Ba2Zn(BO3)2: 0.15Eu3+, yK+ (0≤y ≤ 0.07) phosphors were prepared by high-temperature solid-phase method. The structure, photoluminescence (PL) and other characteristics of the prepared phosphors were studied by X-ray diffraction, ultraviolet–visible spectroscopy, PL spectroscopy and fluorescence lifetime. The concentration quenching mechanism of Eu3+ emission in Ba2Zn(BO3)2 host was investigated. In order to improve the PL performance of Ba2Zn(BO3)2: 0.15 Eu3+ phosphor, the effect of Li+, Na+ and K+ compensators on the PL performance of Ba2Zn(BO3)2: 0.15 Eu3+ luminescent powder was studied. Under excitation at 393 nm, a strong red emission peak is observed at 620 nm. This peak corresponds to the 5D0→7F2 transition and significantly increases its strength by adding a charge compensator. Therefore, the addition of K+ is very effective in improving the PL performance of Ba2Zn(BO3)2: 0.15 Eu3+ phosphors.

Synthesis, structural and optical properties of a novel double perovskite for LED applications

Amidst growing concerns for environmental sustainability and green ecology, the utilization of Light Emitting Diodes (LEDs) for indoor plant cultivation has emerged as an influential area of research. Nonetheless, the growth of indoor plants is often constrained by inadequate lighting. Consequently, designing novel LEDs to create an appropriate light environment has emerged as a focal point in research. As a new type of photocatalytic material with excellent optical properties and light stability, double perovskite has broad application prospects in LEDs manufacturing. In this context, this article aims to synthesize a new Ca2Lu(Nb,Mn)O6 double perovskite and study its optical properties in LEDs lighting for indoor plant growth. A new Ca2Lu(Nb,Mn)O6 double perovskite were synthesized using the traditional high-temperature solid-phase method. The crystal structure and luminescence properties of the double perovskite were characterized in detail using powder X-ray diffraction (XRD), Rietveld refinement, excitation and emission spectra, decay lifetimes, quantum efficiency (QE), electron paramagnetic resonance (EPR) spectra, temperature-dependent emission spectra, and the Commission International de l’Eclairage (CIE) color coordinates. The photoelectric properties of Ca2Lu(Nb,Mn)O6 and Ca2LuNbO6 double perovskite have been explored through first-principles investigations. The absorption spectra from 270 to 600 nm indicates that it can be effectively excited by ultraviolet (UV) light. The emission spectra show a strong broad red emission peak at 684 nm. The luminescence mechanism has been studied using the Tanabe-Sugano diagram. In addition, the internal UV emission ratio β1, crystal field strength Dq, and Racah parameters B and C were evaluated. The thermal stability of the sample was studied through emission spectra at heating temperatures from 303 to 573 K. The results indicate that Ca2Lu(Nb,Mn)O6 double perovskite provides a new solution for indoor plant growth.

Broadband La2LiSbO6: Cr3+ Phosphors with Double Luminescent Centers for NIR pc-LEDs.

The La2LiSbO6: xCr3+ phosphors were synthesized by means of a high-temperature solid-phase method. Based on the differences in ionic radius, valence state, and formation energy, the substitution sites of Cr3+ ions are discussed in detail. The optimized doping concentration of Cr3+ is determined to be 0.01. Under 517 nm excitation, the La2LiSbO6: 0.01Cr3+ phosphor presents a wide emission band (from 700 to 1350 nm) with a peak centered at 952 nm. Additionally, its corresponding full width at half-maximum is 155 nm, and the internal quantum efficiency reaches 62.4%. Meanwhile, the emission intensity of the La2LiSbO6: 0.01Cr3+ phosphor at 373 K is about 63.7% of that at room temperature, exhibiting good thermal stability. Aiming to fabricate a near-infrared phosphor-converted light-emitting diode device, the La2LiSbO6: 0.01Cr3+ phosphor is mixed with epoxy adhesive and cured on a green light-emitting diode chip. Under the irradiation of the fabricated light-emitting diode device, fruits and writing in the dark environment can be captured by a near-infrared camera. Hence, the La2LiSbO6: 0.01Cr3+ phosphor is promising for night vision.

Targeting Zr6Nb2O17 ceramic material with integrated structure and function: From preparation to performance

Herein, we report a kind of structural and functional integrated ceramic material with excellent mechanical and optical properties. A series of Er-doped Zr6Nb2O17 ceramic samples were prepared by the high-temperature solid-phase method, which showed reversible photochromism from light curry to dark brown under the alternating action of 365 nm UV light and heat treatment at 350 °C. The photochromic process is fully reversible and has good cyclic stability with a maximum photochromic contrast of 20.1%. The fluorescence modulation behavior based on the photochromic reaction can effectively modulate the emission of Er3+, and the maximum fluorescence modulation ratio reaches 62%. The best Vickers hardness and fracture toughness values of the prepared Zr6Nb2O17: Er ceramics reached 15.88 GPa and 4.5 MPa m1/2 respectively. The mechanisms of the observed photochromism, photoluminescence, and fluorescence modulation were studied systematically. This work is expected to provide significant guidance for the development of high-performance colored ceramic materials and broaden its market application field.

Preparation and luminescence properties of Ba0.92-xSrxAl2Si2O8:0.08Eu2+ blue-cyan phosphors for white light LEDs

Currently, there is a cyan gap in white light-emitting diodes (LEDs) manufactured by combining near-ultraviolet (NUV) chips with tricolour (blue/green/red) phosphors, resulting in a poor colour rendering index (Ra). Broadband blue-cyan phosphors contain blue, cyan and green luminescent components that complement the cyan gap. In this paper, feldspar-structured Ba0.92-xSrxAl2Si2O8:0.08Eu2+ (x = 0–0.5) phosphors were prepared by a high-temperature solid-phase method and a cation substitution strategy. A phase transition was achieved by varying the concentration of x, which resulted in the formation of two luminescent centres and a 10.33-fold enhancement of the luminescence intensity for Ba0.92Al2Si2O8:0.08Eu2+. The colour of the emission changed from the original green to blue-cyan, and the strongest emission peak with a half-height width of 94.5 nm was observed at a Sr2+ concentration of 0.3 (30%) and covered the blue, cyan and green wavelength ranges (390–600 nm). The experimental value of the optical band of the substrate is 5.71 eV, and the luminous intensity of the Ba0.62Sr0.3Al2Si2O8:0.08Eu2+ sample at 150 °C was 91.3% of that at room temperature. Ba0.62Sr0.3Al2Si2O8:0.08Eu2+, (Ca, Sr) AlSiN3:Eu2+ and 365 nm NUV chips were successfully packaged into white LED devices. The colour rendering index (Ra) of the prepared white LED devices was 87, R9 was 89, the colour coordinates were (0.3763, 0.3382), and the colour temperature was 3759 K, which effectively solves the problem of the lack of cyan luminescent components in white LED devices and simplifies the manufacturing process of white LEDs.

Y2MAl4SiO12:Cr3+ (M=Mg, Ca, Sr, Ba) near-infrared phosphors via chemical unit co-substitution strategy for plant growth

Near infrared light plays an important role in promoting the growth and development of plants. Light at 600–800 nm is conducive to the growth and development of plant stems and leaves. In this study, a series of near-infrared phosphors Y2MAl4SiO12:Cr3+ (M = Mg, Ca, Sr, Ba) were synthesized by high temperature solid phase method. The local environment of Cr3+ in Y3Al5O12(YAG) structure was regulated by different Mg2+/Ca2+/Sr2+/Ba2+-Si4+ co-substituting Y3+-Al3+. The crystal structures of the phosphors were analyzed by X-ray diffraction (XRD) and Rietveld refinement. With the entry of Mg2+→Ba2+ into the matrix lattice, the corresponding luminescence intensity of Mg2+→Ba2+ is enhanced, the spectra show a large degree of redshift of about 50 nm and the spectra of Mg2+→Ba2+ samples widen by 12 nm. The results show Y2BaAl4SiO12: Cr3+ has a better luminescence property and 0.03 mol is an optimized content. The internal quantum efficiency (IQY) is 68.02% and integrated emission intensity at 150 °C remains 40.2% of the initial emission intensity. The calculated activation energy ΔE is 1.58eV. The spectra of Y2BaAl4SiO12:0.03Cr3+ phosphors are well matched with the absorption spectra of PR and PFR, which is expected to have potential applications in plant growth.

Luminescence properties and high energy transfer of Ca9MgNa (PO4)7: Eu2+, Mn2+ blue-red dual emission phosphor for plant growth LEDs

The Ca9MgNa(PO4)7: Eu2+, Mn2+ (CMNPO: Eu2+, Mn2+) phosphors were successfully prepared via high-temperature solid-phase method. Under near ultraviolet light (n-UV) excitation, CMNPO: Eu2+, Mn2+ phosphor exhibits blue and red double emissions centered at 419 nm and 642 nm due to Eu2+: 5d → 4f transition and Mn2+: 4T1(4G) → 6A1(6S) transition, respectively, which match well with the chlorophyll a and b absorption spectrum required for plant growth. The energy transfer (ET) efficiency between Eu2+ and Mn2+ ions was analyzed and is as high as 90.0%. Besides, the luminescence mechanism and ET process of the phosphors were explained according to the simple energy level diagram of Eu2+ and Mn2+ ions. In addition, it was also found that the phosphor has good thermal stability (the luminescence intensity maintains 77.4% at 423 K). Finally, a LED device was packaged with the obtained phosphor Ca9MgNa(PO4)7: 0.03Eu2+, 0.23Mn2+ and a commercial 365 nm n-UV chip, and the corresponding color rendering index Ra and the correlated color temperature (CCT) is 83.6 and 1842 K, respectively. The results show that the optimized phosphor has good application potential in plant cultivation LEDs.

Dy3+/Eu3+/Nb5+ doped NaGdSb2O7 phosphors greatly enhance white light emission

In this paper, a new phosphor NaGdSb2O7 (NGSO) was synthesized by high-temperature solid-phase method, and the transition from cold white light to warm white fluorescence emission was realized by studying the luminous intensity of Dy and Eu under different doping and adjusting the doping ratio of Dy and Eu. In addition, when Nb partially replaces Sb, the band gap of the sample changes, the band structure is changed, and the light intensity is enhanced. The symmetry of the crystal lattice is changed, and the crystal structure is gradually asymmetrical, which promotes the gradual enhancement of fluorescence intensity. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, absorption spectroscopy and fluorescence lifetime were used to measure the parameters of phase purity, valence state, photoluminescence, absorption emission cross-section and fluorescence decay time. All experimental results show that NGSO: Dy, Eu, Nb phosphors have potential application value in the field of white light-emitting diodes (LEDs).