Temperature Solid-state Reaction Method Research Articles

Huge enhancement in upconversion luminescence near-infrared emission of KYb (MoO4)2: Er3+ phosphor by doping Y3+ ions

The KYb(MoO4)2: Er3+, Y3+ phosphors were synthesized by high temperature solid state reaction method. By further doping Y3+ ions, the near-infrared (NIR, 804 nm, 4I9/2 → 4I15/2) luminescence of KYb(MoO4)2: 0.1 % Er3+ phosphor is greatly enhanced. Based on the upconversion luminescence (UCL) spectra, the optimal doping concentration of Y3+ ions were 7.5 %. Its near-infrared UCL intensity is about 26.9 times that of undoped Y3+ ions. Through a series of characterization methods, we find that the enhancement of NIR upconversion emission is due to the generation of defect bands. It plays a crucial role in facilitating the transfer of energy from green light level (2H11/2, 4S3/2) to red light level (4F9/2) and near-infrared level. To explain the luminescence mechanism, the power dependence, UV-VI-NIR absorption spectra, excitation spectra at 804 nm and emission spectra at 380 nm were studied. In addition, the 804 nm single near-infrared UCL intensity of KYb (MoO4)2: Er3+, Y3+ shows a linear variation with temperature in the temperature range of 298 K–673 K. The maximum sensitivity is 0.13 % K−1. This study provides a new method and theoretical support for the application of near-infrared UCL in optical temperature measurement.

Comprehension of the photoinduced charge transfer assisted energy transfer in Gd3+-based host sensitized tellurate phosphors for thermal sensing and anticounterfeiting labels.

A series of novel Eu3+-activated Ba2Gd2/3TeO6 (BGT) phosphors were successfully synthesised via a high temperature solid state reaction method. The crystal structure analysis showed that Eu3+-doped Ba2Gd2/3TeO6 double perovskite phosphors possess monoclinic symmetry with space group P21/n. The as-prepared phosphors can be efficiently excited by far-ultraviolet light to generate reddish orange luminescence of around 593 nm corresponding to the 5D0 → 7F1 transitions of Eu3+ ions. Gd3+ acts as a sensitizer for luminescence enhancement. The highest luminescence intensity corresponded to x = 0.11 Eu3+ concentration, and the critical distance was calculated to be 9.61 Å, indicating that multipolar interaction is behind the concentration quenching mechanism. Besides, the optimum concentration Eu3+-activated Ba2Gd2/3TeO6 phosphor exhibited color co-ordinates of (0.63, 0.36), a high color purity of 94.21% and a quantum efficiency of 18%. JO intensity parameters reveal the slight distortion of the crystal field around the activator ion. Notably, the maximum relative sensitivities of the BGT:0.11Eu3+ phosphor were found to be 0.19% K-1 within the temperature range of 300-500 K and 2.07% K-1 within 80-300 K, and it can potentially be used as a promising thermometer in high and low temperature regions, respectively. The luminescent labels based on fluorescent ink and PL chalk demonstrate the potential application of synthesized phosphors in anti-counterfeiting and security labeling.

Luminescence properties of ZnSxO1-x:Ce3+ phosphors with tunable short fluorescence lifetime

Fluorescence lifetime of phosphors is a critical index in the field of high energy physics and astrophysical detection. A series of ZnSxO1-x:0.05Ce3+ phosphors with tunable short fluorescence lifetime were prepared by performing high temperature solid state reaction method. The phosphors exhibited two mixed phases consisting of the hexagonal phase ZnO and the hexagonal phase ZnS. They are spherical and the average particle size is 2.24 μm. As the component content of the ZnS in ZnSxO1-x:0.05Ce3+ phosphors varies, the emission wavelength can be tuned from 448 nm to 495 nm, the short fluorescence lifetime can be tuned within the range of 6 μs–200 μs. By performing exponential fitting, we obtained the equation for the variation of fluorescence lifetime of ZnSxO1-x:0.05Ce3+ phosphors with ZnS fraction.

Effect of Sm3+ ions doping on the structural and optical properties, Judd-Ofelt and radiative parameters of ZnS phosphor materials

Undoped ZnS and Sm3+ doped with varying concentration of ZnS phosphor materials were synthesized via low temperature solid state reaction method. The samples were investigated for the influence of different concentrations of Sm3+ ions on their structural and spectroscopic properties. The presence of various absorption bands in UV–Vis–NIR spectra revealed the transition from ground state to different excited states of Sm3+ ions. The Judd-Ofelt (JO) analyses were evaluated to identify the structure and the bonding around the Sm3+ ions. The high value of Ω2 intensity parameter reveals that the site symmetry is lower. The parameters such as radiative transition probabilities, radiative lifetime, branching ratio, stimulated emission cross-sections and the optical gain parameters are also evaluated. The PL spectra shows five high intensity emission bands centered at 567 nm, 590 nm, 619 nm, 641 nm and 667 nm corresponding to 4G5/2→6Hj (j = 5/2, 7/2,9/2, 11/2, 13/2) transitions and showed optimum for concentration at x = 0.03 in Zn(1-x)S. The quantum yield of the prepared optimal phosphor using integrating sphere method was found to be 10.08%. This indicates that the materials synthesized may be favorable for the applications of laser and other optical devices.

Visible to ultraviolet C (UVC) up-conversion of Er[formula omitted] doped yttrium aluminium garnet phosphor: Antimicrobial application

In the present work, a visible to ultraviolet C (UVC) up-conversion Er3+ doped yttrium aluminium garnet (YAG) ceramic phosphor was developed by a high temperature solid state reaction method. The structural characterization of the prepared phosphor was carried out using X-ray diffraction analysis and transmission electron microscopy techniques. The up-conversion behaviour of the phosphor was studied by recording the emission spectra of the phosphor under a 460 nm blue LED source. The emission spectrum was obtained in the UV region containing peaks centred at 217, 256, 275 and 312 nm. The emitted UV radiation belongs to the germicidal UV wavelength; therefore this behaviour of the phosphor was applied for the inactivation of surface born microbes through the emitted radiation. The emission behaviour of the phosphor was further investigated by LED encapsulation. The up-conversion emission increases with an increase in the crystal size.

An attempt to enhance the afterglow luminescence of NIR light emitting long persistent phosphor Zn3Ga2Ge2O10:Cr3+ by Pr3+ co-doping

In this study we have focused on the improvement of luminescence intensity and the long afterglow luminescence of Cr3+ doped Zn3Ga2Ge2O10 long persistent phosphor by adding an appropriate amount of Pr3+ ions in proportion with Ga concentration. We have successfully developed a series of long persistent Zn3Ga(2-x-y)CrxPryGe2O10 (where x = 0, 0.04 and y = 0, 0.01, 0.02, 0.03, 0.04) phosphors by high temperature solid state reaction method. The structural properties of the developed phosphors were characterized by X-ray diffraction method. The diffuse reflectance spectra were recorded at room temperature and it shows three strong absorbance bands at the wavelength of 256, 412 and 570 nm due to the transitions of 4A2g→4T1g (4P), 4A2g→4T1g (4F) and 4A2g→4T2g (4F) of Cr+3 ions which are also confirmed from the photoluminescence (PL) excitation spectra. PL emission analysis revealed that developed phosphors have a strong narrow luminescence around 698 nm and significantly enhanced with the Pr3+ content upto its optimum value (0.02). Afterglow NIR light emission from the developed phosphors was captured by night vision monocular and it is found that the phosphors have long persistent luminescence for more than 24 h. Thermoluminescence (TL) measurement was also carried out for better understanding the kinetic mechanism and luminescence process in these materials. This will enable to calculate the trapping parameters associated with prominent glow peaks.

Effect of nano-SiO2 on performances of KBaYSi2O7: Eu3+ red phosphor for NUV-pumped LEDs

KBaY0.9Si2−xSixO7: 0.1Eu3+ phosphors were prepared by traditional high temperature solid state reaction method at 1050 ℃ with nano and micron SiO2 as raw materials. The particle size of nano-SiO2 is 15, 30 and 50 nm. The crystal structure, morphology, luminescence intensity and thermal stability of the samples were characterized by XRD, SEM, photoluminescence spectra and temperature-dependent fluorescence spectra, respectively. The results show that the phosphor is a single matrix, and the mixing of nano-SiO2 increases the particle size and improves crystallization of the phosphor. KBaY0.9Si0.4Si1.6O7: 0.1Eu3+ mixed by nano-SiO2 with particle size of 15 nm has the improved performance of luminescence intensity enhanced by 13.7 % and thermal stability enhanced by 11 %. CIE coordinates are (0.670, 0.330) and close to the standard redlight source. Therefore, KBaY0.9Si0.4Si1.6O7: 0.1Eu3+ has a broad prospect in red phosphors for NUV excited LEDs.

Hetero-valent substitution design of high thermal stability reddish-orange Sr3Ga2Sn1·5Si2·5O14:Sm3+ phosphor for healthy lighting white-light-emitting-diodes applications

In this paper, a novel violet excited reddish-orange emitting Sr3Ga2Sn1·5Si2·5O14:Sm3+ (SGSSO:Sm3+) phosphor with high thermal stability was designed and synthesized by the high temperature solid state reaction method for the first time. The photoluminescence (PL) properties of the SGSSO:Sm3+ phosphors were investigated systematically. Under 402 nm violet light excitation, SGSSO:Sm3+ phosphor shows reddish-orange emission at 598 nm that is attributed to the 4G5/2 → 6H7/2 transition of the Sm3+ ions. Importantly, the PL intensity of SGSSO:Sm3+ at 423 K can maintain 87% of the initial value at room temperature. The high thermal stability of Sm3+ in SGSSO was speculated to be attributed to the energy transfer mechanism of trap formed by the hetero-valent substitution of Sm3+ at Sr2+ sites. Finally, a WLED has been fabricated by combing the violet LED chip with the as-prepared reddish-orange emitting phosphor, commercial blue BaMgAl10O17:Eu2+ (BAM:Eu2+) and green (Ba,Sr)2SiO4:Eu2+ ((Ba,Sr)S:Eu2+) phosphors. The results indicated that the as-prepared SGSSO:Sm3+ phosphor can be a potential candidate of the reddish-orange component for violet chip pumped white-light-emitting-diodes.

Photoluminescence behavior of Eu3+ doped XAl2O4 (X = Mg, Ca, Sr and Ba) phosphors: a comparative study

In this work, the Eu3+ doped stuffed tridymite type structure of alkaline earths aluminate i.e. XAl2O4 (X = Mg, Ca, Sr and Ba) phosphor materials have been synthesized by conventional high temperature solid state reaction method at 1623 K. The Samples were structurally and morphologically characterized by x-ray diffraction (XRD) and Scanning electron microscope (SEM) measurements. The vibrational behavior of the phosphor samples were investigated by Fourier transform infrared (FTIR) measurements. The phosphor samples emit intense red emission in 610–615 nm range due to 5D0 → 7F2 transition of Eu3+ ion on excitation with charge transfer band (CTB) wavelength arising due to Eu3+-O2- and also by the discrete bands of Eu3+ ions .The decay time of 5D0 level of Eu3+ ion were recorded on excitation with 393 nm and by the CTB wavelength for all the four samples. The optimized 1 mol% Eu3+ doped CaAl2O4 phosphor exhibits optimum emission intensity and color purity under the excitation with 393 nm than others. The decay time is also found to be larger in the case of Eu3+ doped CaAl2O4 phosphor sample. Therefore, Eu3+ doped CaAl2O4 phosphor may be promising material for red color light emitting applications and white light generation.

Optical properties of brannerite-type vanadium oxides, MV2O6 (M = Ca, Mg, Mn, Co, Ni, Cu, or Zn)

The optical properties of brannerite-type oxides MV2O6 (M ​= ​Ca, Mg, Mn, Co, Ni, Cu, or Zn) and solid solutions synthesized by conventional high temperature solid state reaction method are compared in the present study. The structural phase transformation from pseudo-brannerite to brannerite was found at x ​≥ ​0.6 in the solid solution Ca1-xMnxV2O6 (x ​= ​0 - 1). In the new solid solution of Zn1-xCoxV2O6 (x ​= ​0 - 1), the phase transformation from brannerite to NiV2O6-type occurred at x ​≥ ​0.8. A systematic decrease in the optical band gap with increasing Mn content in Ca1-xMnxV2O6 resulted in the change in the colors of the samples. In Zn1-xCoxV2O6, the prominent d-d transitions of Co2+ ion in addition to the band gap narrowing altered the colors. The variation in the colors of brannerite-type oxides can be understood based on the changes in the optical band gap, ligand-to-metal (O2--V5+) and/or metal-to-metal (M2+-V5+) charge transfer transitions, and d-d transitions.

Emission and EPR studies on green and red color emitting gallate phosphor containing manganese/chromium ions

The ZnGa2O4:Mn2+/Cr3+ ceramic phosphor is synthesized via high temperature solid state reaction method and then phosphor is intensively studied for green/red color emission. Prepared samples are structurally characterized through powder X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) and it is found that the samples possess single phase cubic spinel structure. The X-ray photoelectron spectroscopy (XPS) is performed for the identification of chemical states of different elements present in the samples. The Zn0.9Ga2O4:0.1%Mn2+ sample has shown broad emission band (475–575 nm) having peak at 505 nm (green) due to the electronic transition of Mn2+ ion. The ZnGa1.9O4:0.1%Cr3+ sample has shown intense emission at 696 nm (deep red) due to the 2E (2G) →4A2(4F) transition of Cr3+ ions. The co-doped Zn0.9Ga1.9O4:Mn2+/Cr3+ sample on the other hand can be excited with different excitations to give green and red emissions. Electron paramagnetic resonance (EPR) spectroscopy is done to inspect defects caused by the substitution of Ga3+ and Zn2+ by Cr3+ and Mn2+ ions, respectively. Emission decay measurements are done to decipher afterglow and photoluminescence decay.

Impact of A-site calcium on structural and electrical properties of samarium cobaltite perovskites

Perovskite structured samarium cobaltite ceramics materials having good electric, dielectric and modulus characteristics are used as potential candidate in several device applications. The present study discusses the structural and dielectric properties of Sm1-xCaxCoO3 (x = 0.0,0.05,0.1,0.2,0.3) (SCC) synthesised by high temperature solid state reaction method. The x-ray diffraction analysis confirmed the orthorhombic phase for the synthesised samples at room temperature. Scanning electron microscopy of the sample strongly supports the formation of regular distribution of grains with desirable density. The impedance, dielectric permittivity and modulus spectrum of SCC were studied in a wide frequency (100 Hz-1MHz) range at various temperature. From the complex modulus analysis, the conductivity relaxation in SCC have been studied. The dependence of dielectric properties of these material on frequency indicates its ferroelectric nature. AC conductivity formalism has also been studied.

Crystal chemistry, DFT calculation and optical properties of the double perovskite stannate Sr2Sn0.8In0.8W0.4O6

Sr2Sn0.8In0.8W0.4O6 double perovskite powder was, first, prepared following an experimental study on the effects of substitutions of In and W in the high transparent strontium stannate SrSnO3 (SSO). The high temperature solid state reaction method was adopted for the preparation of the desired phase. Further, the W and In substitution's effects on the variation of the electronic structure was investigated theoretically by density functional theory (DFT) calculations. Rietveld's refinement of the X-ray diffraction pattern announces a tetragonal symmetry of the crystal lattice (I4/m), characterized by a reduction in octahedral inclinations due to double substitution. IR absorption spectroscopy announced the presence of carbonates and water molecules due to moisture-swing sorption and confirmed by TG analysis. The optical properties studied by UV-Vis spectroscopy have shown that the material is transparent in the visible region of the spectrum. A band gap of 3.46 eV was calculated using Tauc plot, indicating a possible semiconducting behavior.

Room temperature intrinsic diluted magnetic semiconductor Li(Cd,Mn)As

Li1.04(Cd1−xMnx)As DMSs were synthesized by a high temperature solid state reaction method. A Curie temperature of 318 K has been achieved forx= 0.08. The hysteresis loops at different temperatures demonstrate room temperature ferromagnetism.

Excellent upconversion luminescence and temperature sensing performance of CdMoO4:Er3+,Yb3+ phosphors.

In this paper, Er3+/Yb3+ co-doped CdMoO4 phosphors were prepared by a traditional high temperature solid state reaction method. Based on the 3D network structure of the CdMoO4 host and the efficient Er3+/Yb3+ upconversion luminescence combinations, excellent green emission properties were observed when the prepared sample is irradiated with a laser at about 980 nm. For optical temperature sensors based on the fluorescence intensity ratio (FIR), the prepared phosphors have excellent sensitivity to temperature in the range of 293 to 473 K. With increasing environmental temperatures, the absolute sensitivity of the CdMoO4:0.02Er3+,0.08Yb3+ sample reached a maximum at about 473 K (Sa = 1.388% K-1). The calculated relative sensitivity of the optical temperature sensor was Sr = 1.631% K-1 at 293 K. This is due to the sensitive thermally coupled energy levels (TCLs) of the Er3+ ions (2H11/2 and 4S3/2) in the CdMoO4 structure. Therefore, it is shown that the prepared CdMoO4:0.02Er3+,0.08Yb3+ phosphor has excellent applications in non-contact optical temperature measurement.

Photoluminescence properties, excellent thermal stability and energy transfer in Ce3+ and Tb3+ co-doped Sr3Gd2(BO3)4 phosphors

Sr3Gd2(BO3)4: Ce3+, Sr3Gd2(BO3)4: Tb3+ and Sr3Gd2(BO3)4: Ce3+, Tb3+ phosphors were synthesized through conventional high temperature solid state reaction method. Phase purity, crystal structure, photoluminescence properties, and lifetime of the samples were analyzed in detailed. Sr3Gd2(BO3)4: Ce3+ showed a bright blue broad emission band, which was attributed to 4f → 5d transitions of the Ce3+ ions, and it exhibited two broad excitation ranged from 200 nm to 400 nm. For all Sr3Gd2(BO3)4: Tb3+ samples, under ultraviolet excitation bands of 240 nm, four emissions peaked at 490 nm, 544 nm, 585 nm and 623 nm appeared, due to the 5D4 → 7FJ (J = 6, 5, 4, 3) transitions of Tb3+ ions. For the Sr3Gd2(BO3)4: Ce3+, Tb3+ phosphors, the lifetime of the samples were analyzed, which showed the presence of energy transfer between the Ce3+ and Tb3+. The energy transfer efficiency from Ce3+ ions to Tb3+ ions reached 98.37%. When the temperature reached 443 K, the luminescence intensity reached 88% of the initial value. Finally, a white LED was fabricated by using a 365 nm near ultraviolet LED chip combined with BaMgAl10O17: Eu2+ (blue), Sr3Gd0.91(BO3)4: 0.09Ce3+, 1.0 Tb3+ (green), and CaAlSiN3: Eu2+ (red) phosphors. The color coordinates was (0.40, 0.42); correlated color temperature was 3721 K; color rendering index was 91.1. The results showed that the Sr3Gd2(BO3)4: Ce3+, Tb3+ green phosphors were suitable for white LEDs.

Structural and electrical investigation of ‘Bi’ doped SmFeO3-BaTiO3 perovskite system

The polycrystalline ceramic (Sm0.75Bi0.25FeO3)0.5 (BaTiO3)0.5 (SF-BT) is synthesized by high temperature solid state reaction method at an optimized temperature 1250 °C. The sample is investigated for its multifunctionality by analyzing its structural and electrical properties. The room temperature XRD pattern confirms the single phase compound in the tetragonal symmetry. The symmetry of the compound have been verified by commercially available software POWD. Complex impedance studies confirm the grain contribution to the electrical properties in the material. It reveals semiconducting behaviour of the material and transport phenomena is due to short range mobility of charge carriers. The relaxation mechanism in the sample is due to the short-range mobility of charge carriers.

Enhanced self-activated far-red photoluminescence from Sr3LiSbO6 phosphors by Gd3+ doping for plant growth

Sr3LiSbO6 phosphors were prepared by high temperature solid state reaction method. The crystal phase, morphology and optical properties were characterized by X-ray powder diffraction spectroscopy, scanning electronic microscope, absorption and photoluminescence (PL) spectra. The XRD Rietveld refinement was performed to obtain the detailed crystal structure of Sr3LiSbO6. The electronic structure was analyzed by density functional theory (DFT) calculation. Sr3LiSbO6 possessed indirect band structure and the band-gap were determined to be 3.17 eV. Self-activated far-red emissions at 630–800 nm were detected under the excitation at 340 nm, which was proposed to originate from the transition between interstitial oxygen defective state to six hybrid 4d105s0 states of Sb5+ according to the results of PL spectra of samples annealed at different atmospheres. The PL intensity can be significantly enhanced by 2.9 times after doping 2 mol% Gd3+ ions in Sr3LiSbO6. The internal quantum efficiency of Sr3LiSbO6:2 mol%Gd3+ was determined to be 25.2%. The influence of the Gd3+ doping on the self-activated PL lifetimes of Sr3LiSbO6 and the thermal quenching property of Sr3LiSbO6:2 mol%Gd3+ was studied.

Host dependent upconversion, color tunability and laser induced optical heating via NIR excitation in Ho3+, Yb3+ doped YXO4 (X = V, Nb, Ta) phosphor materials: Application as a security tool and optical heater

This work reports a comparative upconcversion (UC) emission study of the Ho3+, Yb3+co-doped in pure YVO4, YTaO4, YNbO4 and in their mixed (YTa1-xVxO4, YTa1-yNbyO4, YNb1-zVzO4, where x, y, z= 0, 0.25, 0.50 and 0.75, 1 mol) phosphor materials synthesized via high temperature solid state reaction method at 1473 K. The pure and the mixed phosphors have been structurally analysed through X-ray diffraction technique. The phonon frequencies and the surface morphologies are investigated through Fourier transform Infrared (FTIR) and scanning electron microscope (SEM) techniques for pure and mixed compositions. Under NIR (980 nm) excitation, YNbO4:Ho3+,Yb3+ and YTaO4:Ho3+,Yb3+phosphors emit intense green alongwith weak red and very weak NIR UC emissions, whereas the YVO4:Ho3+,Yb3+ phosphor exhibits strong red emission with weak green and NIR UC emissions. The UC emissions in the three cases is explained using energy level diagram and the phonon frequency of the host matrix. The pure YNbO4 host shows comparatively efficient UC emission than the other two due to its large particle size and low phonon frequency. Therefore, the YNbO4:Ho3+,Yb3+ serves as an excellent infrared to green upconverter and useful in display devices.On the other hand, the color tunability from green to orange/red UC emissions is observed on varying the vanadate (V) concentration in the mixed compositions (in YTa1-xVxO4 and YNb1-zVzO4). The variation of ‘V’ in YTa1-xVxO4:Ho3+,Yb3+ and in YNb1-zVzO4:Ho3+,Yb3+intensify the vibrational bands which promotes the non-radiative relaxation and hence tune the upconversion emission color as well as the intensity. The UC emission intensity in YTa1-xVxO4:Ho3+,Yb3+is maximum for x= 0.25. For higher concentrations of V, the green to orange/red color tunable emission is observed. Thus, the mixing of ‘V’ acts as sensitizer as well as modulater in YTa1-xVxO4:Ho3+,Yb3+ phosphor. The colortunable emission in mixed compositions with high color purity makes it promising for security and display applications. The mixing of different compositions of NbO4 and VO4 give different proportions of red and green emissions. On the other hand, mixing of NbO4 and TaO4 give intense green color. Such type of materials are also very useful in security ink applications.The laser induced optical heating is found maximum in case of pure YVO4:Ho3+,Yb3+ phosphor. The temperature of sample YVO4:Ho3+,Yb3+ increases upto 353 K at power density 107.59 W/cm2. Therefore, the YVO4:Ho3+,Yb3+ can be used as an optical heater in medicals such as physiotherapy, cancer and wound treatments etc.

Improvement of luminescent intensity of ZnMoO4: Sm3+ phosphor by introducing alkali metal as charge compensation agent

The high temperature solid state reaction method was employed to synthesize a series of ZnMoO4: xSm3+ (x ​= ​0.001, 0.002, 0.003, 0.004, 0.005) and ZnMoO4: 0.003Sm3+, 0.003A+ (A ​= ​Li, Na, K) phosphors. The phase composition was studied by X-ray diffraction analysis. The Rietveld XRD refinement of the ZnMoO4: 0.005Sm3+ shows the effect of Sm3+ doping on the crystal lattice. The luminescent properties of the phosphors are studied, and the influence of alkali metal charge compensators on the luminescent properties is explored. The co-doping of alkali metals has a significant effect on the luminescence intensity and decay time of Sm3+ doped phosphor. The symmetry of Sm3+ sites in the ZnMoO4 crystal lattice was evaluated according to the transition intensities of 4G5/2→6H9/2 magnetic dipole transition and 4G5/2→6H9/2 electric dipole transition. The density of states of phosphors was studied by first-principles calculation via Vienna Ab-initio Simulation Package (VASP).