Electromagnetic wave absorption properties of cobalt-zinc ferrite nanoparticles doped with rare earth elements

Traditional ferrites are of poor electromagnetic wave (EMW) absorption while doping rare earth elements (REEs) can greatly enhance their permeability to improve the EMW loss performance. In this study, Co-Zn ferrite nanoparticles doped with various amounts of REEs (Gd³⁺, Nd³⁺ and Pr³⁺) were synthesized by a hydrothermal method, and their particle morphology and an EMW absorption performance were characterized by using transmission electron microscopy (TEM) and a Vector network analyzer (VNA). The results show that the initial spherical Co-Zn ferrite nanoparticles present an irregular quadrilateral structure after Gd³⁺ doping, and the average particle size of Co_0.5Zn_0.5−xGd_xFe₂O₄ increases from 26 to 50 nm with x increasing from 0 to 0.35. At x of 0.25, the reflectivity absorbance achieves −27.94 dB at 18 GHz with the effective absorption bandwidth (EAB) of 4.08 GHz at a sample thickness of 2.5 mm. When Nd³⁺ doping amount reaches x = 0.3, the minimum reflection loss (RL) is −25.63 dB at 18 GHz and EAB is 3.91 GHz. Doping Pr³⁺ (x = 0.25) in the sample broadens EAB, and the minimum RL is −16.1 dB at 16.81 GHz and EAB is 7.31 GHz. This study shows that the magnetic moment produced by doping REES can form magnetic domains, which affects the incident EMW and improves the magnetic loss. It is expected that REEs-doped Co-Zn ferrite nanoparticles can be used as efficient electromagnetic shielding materials in aerospace.     

Physicochemical properties of Li3Ba2La3(MoO4)8:Eu,Tb red-emitting phosphor for solid state white lamps

In this work,combustion synthesis was used for the first time to fabricate a phosphor material with red emission for applications in solid-state white-light lamps.We synthesized a material with emission wavelength at λ_em=617 nm,excited under long UV-blue wavelength based on Eu³⁺,Tb³⁺-activated molybdates Li₃Ba₂(La_1-x-yEu_xTb_y)₃(MoO₄)₈ with 0 ≤ x ≤1 and 0 ≤ y ≤ 1.A series of pow...     

Emission-tunable Ba2Y1–xScxNbO6:Bi3+ (0 ≤ x ≤ 1.0) phosphors for white LEDs

Here, we report a series of Bi³⁺-doped Ba₂Y_1–xSc_xNbO₆ (0 ≤ x ≤ 1.0 mol) phosphors by using the traditional high temperature solid-state reaction. To achieve the structural and photoluminescent (PL) information, several experimental characterizations and theoretical calculations were carried out, including X-ray diffraction (XRD), Rietveld refinement, UV-visible diffuse reflectance and PL spectra, temperature dependent PL spectra, and density functional theoretical (DFT) calculations. The XRD results show that the Bi³⁺-doped Ba₂Y_1–xSc_xNbO₆ samples belong to the double-perovskite phase with a cubic space group of Fm3?m, and the diffraction positions shift toward high diffraction angle when the larger Y³⁺ ions are gradually replaced by the smaller Sc³⁺ ions. In addition, the refined XRD findings show that the Bi³⁺ ions tend to substitute the Y³⁺ and Sc³⁺ sites in the Bi³⁺-doped Ba₂Y_1–xSc_xNbO₆ (0 < x < 1.0 mol) solid solutions. The PL spectra show that the emission positions of the solid solution samples tune from 446 to 497 nm with the increase of Sc³⁺ content, which can be attributed to the modification of crystal field strength around Bi³⁺ ions. Moreover, there is energy transfer from the Ba₂YNbO₆ host to Bi³⁺ ions, which is dominated by a resonant type via a dipole-quadrupole (d-q) interaction. The Ba₂Y_0.6Sc_0.4NbO₆:0.02 molBi³⁺ shows the strongest PL intensity under 365 nm excitation, with the best quantum efficiency (QE) of 68%, and it keeps 60% of the room temperature emission intensity when the temperature increases to 150 °C, meaning that the Ba₂Y_0.6Sc_0.4NbO₆:Bi³⁺ features excellent thermal quenching of luminescence. By combining this optimal sample with a commercial red-emitting Sr₂Si₅N₈:Eu²⁺ phosphor, and a commercial 365 nm UV LED chip, a white LED device, with the color temperature (CT) of 3678 K, color rendering index (CRI) of 67.9, and CIE coordinates at (0.371, 0.376), is achieved.     

Impact of La3+ substitution on electrical,magnetic, dielectric and optical properties of Ni0.7Cu0.1Zn0.2LaxFe2–xO4 (0 < x < 0.035) system

The oxalate co-precipitation method was used to synthesize the La³⁺ substituted Ni–Cu–Zn (La–NCZ) nanoferrites having chemical composition Ni_0.7Cu_0.1Zn_0.2La_xFe_2–xO₄ (x = 0, 0.015, 0.025 and 0.035). DC resistivity study of nanoferrites shows both the conducting and semiconducting behaviour. The room temperature DC electrical resistivity of Ni–Cu–Zn (NCZ) nanoferrites decreases, whereas Curie temperature increases with increasing La³⁺ content. In the temperature range of 30–170 °C nanoferrites show p-type semiconducting behavior except x = 0.015; thereafter, they show n-type behaviour. The frequency dispersive initial permeability (μ_i) associated with its real and imaginary (μ′ and μ") parts are attributed to the domain wall movement and magnetic spin resonant. The μ_i, μ′ and μ" of La–NCZ nanoferrites are higher than those of pure NCZ nanoferrite. Dielectric constant (ε′), dielectric loss (ε″) and AC resistivity (ρ_AC) of La–NCZ nanoferrites show normal dielectric behaviour. It is found that ε′ of NCZ nanoferrites decreases with the increasing content of La³⁺ ions. The bandgap energy of La–NCZ nanoferrites is achieved in the range 1.36–1.70 eV confirming the semiconducting nature of materials.     

Fabrication and photoluminescence characteristics of novel red-emitting Ba2LuNbO6:Eu3+ double-perovskite phosphors on near UV WLEDs

Red emitting phosphors play a significant role in accelerating the improvement of illumination quality for white light emitting diodes (WLEDs). In this work, by using solid-state reaction method, an efficient novel Ba₂LuNbO₆:Eu³⁺ phosphor with double-perovskite structure was successfully prepared. Here, a series of Ba₂LuNbO₆:Eu³⁺ red phosphors can be efficiently pumped by the near-ultraviolet (UV) light and then present high-brightness at orange emission (598 nm, ⁵D₀→⁷F₁) and red emission (610 nm, ⁵D₀→⁷F₂). The ratio values of 610 to 598 nm in Ba₂LuNbO₆:Eu³⁺ phosphors exceed 1 when the content of Eu³⁺ is larger than 0.4 mol, because the occupation of Eu³⁺ ions is changed from Lu³⁺ ions with symmetric sites to Ba²⁺ ions with asymmetric sites. Besides, the optimized concentration of Eu³⁺ at the ⁵D₀→⁷F₂ transitions is obtained when x = 1, indicating that there is non-concentration quenching in Ba₂LuNbO₆:Eu³⁺ phosphors. Moreover, the CIE chromaticity coordinates of Ba₂LuNbO₆:Eu³⁺ was calculated to be (0.587, 0.361), the color purity was calculated to be 72.26% and internal quenching efficiency (IQE) was measured to be 67%. Finally, the thermal stability of Ba₂LuNbO₆:Eu³⁺ phosphors was also studied. Our work demonstrates that the novel double-perovskite red-emitting Ba₂LuNbO₆:Eu³⁺ phosphors are prospective red emitting elements for WLEDs applications.     

Improving luminescence and thermometric performance of Ba2CaWO6:Er3+ by tri-doping with Yb3+ and Na+

The Er³⁺doped double perovskite Ba₂ CaWO₆ crystal is a promising ratiometric thermometer based on the fluorescence intensity ratio(FIR) of transitions from ² H_11/2 and ⁴ S_3/2to the lowered ⁴ I_15/2 level.However,the Ca²⁺vacancy defect caused by the charge difference between rare-earth ions and the substituted alkaline-earth ions gives rise to the non-radiative probability and limits the t...     

Er3+-substituted W-type barium ferrite: preparation and electromagnetic properties

Er3+-substituted W-type barium ferrites Ba1-xErx(Zn0.3Co0.7)2Fe16O27(x=0.00,0.05,0.10,0.15,0.20)were synthesized by polymer adsorbent combustion method.Samples were characterized by X-ray diffraction analysis(XRD),X-ray fluorescence(XRF),scanning electron microscopy(SEM)and network analyzer to investigate the relationships among Er3+concentration,crystal structure,surface mcrphology and electromagnetic properties.All the XRD patterns showed pure phase of W-type barium ferrite when x≤0.15,while the impurity phase of ErFeO3 appeared when x=0.20.The pure W-type barium ferrite showed a hexagonal flake shape.In addition,the microwave electromagnetic properties of samples were analyzed in the frequency range of 2-18 GHz.It was indicated that the electromagnetic properties were significantly improved when Er3+doping content was 0.10.The reasons were also discussed using electromagnetic theory.The optimized ferrite exhibited excellent microwave absoption performance.The maximum of reflection loss(RL)reached about-27.4 dB and RL was below-10dB at the frequency range from 8.4 GHz to 18 GHz,when the thickness was 2.6 mm.     

Synthesis and optical properties of novel apatite-type NaCa3Bi(PO4)3F:Dy3+ yellow-emitting fluorophosphate phosphors for white LEDs

In this study, novel yellow-emitting fluorophosphate NaCa₃Bi(PO₄)₃F phosphors doped with different concentrations of Dy³⁺ ions were first obtained via high-temperature solid-state reaction. The crystal structure, phase purity, particle morphology, photoluminescence (PL) properties, thermal stability, and luminescence decay curves of the resulting phosphors were then characterized in detail. Under the excitation of 349 nm, the three dominant peaks of the NaCa₃Bi(PO₄)₃F:Dy³⁺ are centered at 480 nm (⁴F_9/2-⁶H_15/2), 577 nm (⁴F_9/2-⁶H_13/2), and 662 nm (⁴F_9/2-⁶H_11/2). The optimal doping concentration of Dy³⁺ ions in the NaCa₃Bi(PO₄)₃F:xDy³⁺ phosphors is x = 5 mol%. The phosphors show excellent thermal stability with high activation energy (E_a = 0.32 eV). Eventually, the synthesized white light-emitting diode (w-LED) demonstrates the Commission International de L'Eclairage (CIE) chromaticity coordinates of (0.341, 0.334), a good correlated color temperature (CCT) of 5083 K, and a high color rendering index (R_a) of 92. Revealing its potential as yellow-emitting phosphors, the feasibility of the fabricated apatite-type NaCa₃Bi(PO₄)₃F:Dy³⁺ fluorophosphate phosphors was confirmed for w-LEDs.     

Synthesis and enhanced photoluminescence properties of red emitting divalent ion (Ca2+) doped Eu:Y2O3 nanophosphors for optoelectronic applications

This work presents the synthesis of Y₂O₃:Eu³⁺,xCa²⁺ (x = 0 mol%, 1 mol%, 3 mol%, 5 mol%, 7 mol%, 9 mol%, 11 mol%) nanophosphors with enhanced photoluminescence properties through a facile solution combustion method for optoelectronic, display, and lighting applications. The X-ray diffraction (XRD) patterns of the proposed nanophosphor reveal its structural properties and crystalline nature. The transmission electron microscope (TEM) results confirm the change in the shape of the particle and aggregation of particles after co-doping with Ca²⁺. Fourier transform infrared spectroscopy (FTIR) and Raman vibrations also confirm the presence of Y–O vibration and subsequently explain the crystalline nature, structural properties, and purity of the samples. All the synthesized nanophosphors samples emit intense red emission at 613 nm (⁵D₀→⁷F₂) under excitation with 235, 394 and 466 nm wavelengths of Eu³⁺ ions. The photoluminescence (PL) emission spectra excited with 235 nm illustrate the highest emission peak with two other emission peaks excited with 466 and 394 nm that is 1.4 times higher than 466 nm and 1.9 times enhanced by 394 nm wavelength, respectively. The emission intensity of Y₂O₃:Eu³⁺,xCa²⁺ (5 mol%) is increased 8-fold as compared to Eu:Y₂O₃. Doping with Ca²⁺ ions enhances the emission intensity of Eu:Y₂O₃ nanophosphors due to an increase in energy transfer in Ca²⁺→Eu³⁺ through asymmetry in the crystal field and by introduction of radiative defect centers through oxygen vacancies in the yttria matrix. It is also observed that the optical band gap and the lifetime of the ⁵D₀ level of Eu³⁺ ions in Y₂O₃:Eu³⁺,xCa²⁺ nanophosphor sample gets changed with a doping concentration of Ca²⁺ ions. Nanophosphor also reveals high thermal stability and quantum yield as estimating activation energy of 0.25 eV and 81%, respectively. CIE, CCT, and color purity values (>98%) show an improved red-emitting nanophosphor in the warm region of light, which makes this material superior with a specific potential application for UV-based white LEDs with security ink, display devices, and various other optoelectronics devices.     

Selective microwave absorption in Nd3+ substituted barium ferrite composites

Microwave(MW) frequency based wireless communications and electronic devices became prospective due to several ramifications.To meet this need,a series of neodymium ions(Nd3+) substituted barium ferrite composites with composition(20)BaO:(80-x)Fe_2 O_3:(x)Nd_2 O_3(0≤x≤3 mol%) was prepared at1100℃using solid-state reaction method.We evaluated the effect of various Nd3+ions contents on the surface morphology,structure,and magnetic properties of the as-synthesized barium ferrite composites.Meanwhile,microwave reflection loss,complex permittivity and permeability were determined using the transmission/reflection line method in the X-band(8—12 GHz).SEM image of the composites shows that the surface morphology consists of rough and porous microstructures.XRD patterns of the un-doped composites reveal the existence of BaFe_(12)O_(19)(hexagonal) and Fe_(21.333)O_(32)(tetragonal) crystalline phases.Furthermore,a new hexagonal crystalline phase of Ba_6 Nd_2 Fe_4 O_(15) with the crystallite sizes between 15 and 67 nm is observed due to Nd3+ions substitution in the composite.The saturation magnetization of the composite containing 2 mol% of Nd3+does not exhibit any significant alteration compared to the one devoid of Nd3+.The complex relative permitivity and permeability of the achieved composites enriched in Ba_6 Nd_2 Fe_4 O_(15) and BaFe_2 O_4 phases disclose significant MW frequency dependence.The composites also display selective MW absorption in the X-band which could be useful for diverse applications.     

Energy transfer and luminescent properties of Tb3+ and Tb3+, Yb3+ doped CNGG phosphors

In this work,calcium niobium gallium garnet(Ca₃ Nb_1.6875Ga_3.1875O₁₂-CNGG) ceramic samples singledoped with Tb³⁺ and co-doped with Tb³⁺ and Yb³⁺ ions were sintered by the solid-state reaction method.The structural characterization of the samples was carried out by X-ray diffraction measurements.The optimal concentration of Tb³⁺ ions corresponding to the maximum luminescence in the green spectral range in CNGG:...     

Fabrication and long persistent luminescence of Ce3+-Cr3+ co-doped yttrium aluminum gallium garnet transparent ceramics

Persistent luminescence (PersL) materials are widely used in safety indication, traffic and transportation signs, architectural decoration and other fields. In this paper, (Y_1?xCe_x)₃(Al_0.9995Cr_0.0005)₂Ga₃O₁₂ (x = 0.001, 0.002, 0.003, 0.005) transparent ceramics were successfully prepared by solid-state reaction method in air followed by HIP post-treatment. With the increase of Ce³⁺ doping concentration, the optical quality of the as-prepared ceramics is improved and the morphology is denser. Luminescent quenching occurs when the Ce³⁺ concentration is more than 0.2%. The as-prepared transparent ceramics were annealed in different atmospheres. From the PersL decay curves, the transparent ceramics after air annealing show the best PersL performance: luminance with 4424.0 mcd/m² and PersL duration over 865 min after ceasing 365 nm excitation, respectively. The effects of Ce³⁺ doping concentration and annealing atmospheres are also discussed in detail.     

A novel blue-light excitable Pr3+ doped(Sr,Ba)LaMgTaO6 phosphor for plant growth lighting

In this work,a series of Pr³⁺ ions doped(Sr,Ba)LaMgTaO₆ phosphors were prepared and applied for plant growth lighting.Under 450 nm excitation,(Sr,Ba)LaMgTaO₆:Pr³⁺ exhibits intense reddish emission at around 650 nm which is assigned to the ³p₀→³F₂ transition of Pr³⁺ ions.The luminescence intensity reaches to the maximum at 2.5 mol% Pr³⁺ doping content both in SrLaMgTaO₆:Pr^...     

Site occupation and energy transfer in full color emitting phosphor Ba2Ca(BO3)2:Ce3+(K+),Eu2+,Mn2+

White light-emitting diodes (WLEDs) fabricated by single-phase full color emitting phosphor are an emerging solution for health lighting. The crystallographic site occupation of activators in a proper host lattice is crucial for sophisticated design of such phosphor. Here, we report a high quality white light-emitting phosphor Ba₂Ca(BO₃)₂:Ce³⁺(K⁺),Eu²⁺,Mn²⁺ with spectral distribution covering whole visible region. Blue light emission originates from Ce³⁺ ions occupying preferentially Ba²⁺ site by controlling synthesis conditions. Green and red lights are obtained from Eu²⁺ occupying Ba²⁺ (and Ca²⁺) site and Mn²⁺ occupying Ca²⁺ site, respectively. In this triple-doped phosphor, strong red emission with a low concentration of Mn²⁺ is realized by the efficient energy transfer from Ce³⁺ and Eu²⁺ to Mn²⁺. Furthermore, high quality white light is accomplished by properly tuning the relative doping amount of Ce³⁺(K⁺)/Eu²⁺/Mn²⁺ based on efficient simultaneous energy transfer. The results indicate that Ba₂Ca(BO₃)₂:Ce³⁺(K⁺),Eu²⁺,Mn²⁺ is a promising white light-emitting phosphor in WLEDs application.     

Effect of doping of different rare earth (europium,gadolinium, dysprosium and neodymium) metal ions on structural,optical and photocatalytic properties of LaFeO3 perovskites

Different rare earth substituted perovskites LaRE_xFe_(1-x)O_3(where RE=Eu~(3+),Gd~(3+),Dy~(3+),Nd~(3+)and x=0.02,0.04,0.06,0.08,0.1) with orthorhombic structure and narrow band gaps were successfully fabricated via sol-gel autocombustion method.All the substituted perovskites are found to exhibit excellent photocatalytic activity towards the oxidative degradation of dye molecules.An excellent increase in the rate constant values of pure perovskite(LaFeO_3) photocatalytic reactions is observed with the substitution of rare earth metal ions.Best results are obtained for LaNd_(0.1)Fe_(0.9)O_3 which exhibits around 7 times increase in the rate constant values for degradation reaction of SO(1.76×10~(-1) min~(-1))and RBY(1.69×10~(-1) min~(-1)) dyes.     

Synthesis and luminescent properties of Ba3Y3.88Gd0.12O9:Eu3+ phosphors with enhanced red emission

In this work, the Gd³⁺/Eu³⁺ activated Ba₃Y₄O₉ (BYO) phosphors were successfully synthesized via coprecipitation method at 1400 °C. The precursor composition, crystal structure stability, microscopic morphology, photoluminescence (PL)/photoluminescence excitation (PLE) spectra and fluorescence attenuation analysis of the phosphors are discussed in detail. The chemical composition of the precursor was determined by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetry (TG) analysis; According to field emission-scanning electron microscopy (FE-SEM) analysis, it is found that the particle size of phosphor is uniform and the agglomeration is few. According to PL/PLE spectra analysis, Ba₃Y_3.28Eu_0.6Gd_0.12O₉ phosphors has the strongest excitation band at 260 nm and the strongest emission band at 614 nm, and the fluorescence intensity of Ba₃Y_3.28Eu_0.6Gd_0.12O₉ is higher than that of Ba₃Y_3.4Eu_0.6O₉. The quenching concentration of Eu³⁺ in Ba₃Y_3.88–4xEu_4xGd_0.12O₉ phosphors is x = 0.15 and the mechanism of quenching concentration of Eu³⁺ is electric dipole-quadrupole type interactions. The lifetime value of Ba₃Y_3.88–4xEu_4xGd_0.12O₉ (x = 0.15) phosphors is 0.686 ms and decreases with the increase of Eu³⁺ content. In addition, the CIE chromaticity diagram of Ba₃Y_3.28Eu_0.6Gd_0.12O₉ phosphors is (0.66, 0.34). Finally, the lamp beads assembled with Ba₃Y_3.28Eu_0.6Gd_0.12O₉ phosphors have an ideal luminous effect. Therefore, the Ba₃Y_3.88–4xEu_4xGd_0.12O₉ phosphors designed in this work may hopefully meet the requirements of various lighting and optical display applications.     

Microstructure and microwave dielectric properties of Ba6-3xSm8+2xTi18O54 ceramics with various BaxSr1-xTiO3 additions

The Ba6-3xSm8+2xTi18O54 (x=2/3) microwave dielectric ceramics were prepared by traditional solid sate reaction technique. The ex-periment was based on the Ba6-3xSm8+2xTi18O54 (BST) microwave dielectric ceramics doped with a certain amount of Bi2O3, then the effects of BaxSr1-xTiO3 additives on the structure and microwave dielectric properties of Ba6-3xSm8+2xTi18O54 ceramics were investigated using X-ray diffraction and scanning electron microscopy. In this study, the small amount substitution of Sr for Ba was effective for the microwave dielec-tric properties of BST, especially the τf could be tuned to near zero. The result showed that the BST possessed excellent dielectric properties when the addition of Bi2O3 and BaxSr1-xTiO3 was 1 wt.% respectively: εr=79.6, Q?f=10789 GHz, τf=-1.5 ppm/oC.     

Photoluminescence emissions of Ca1−xWO4:xEu3+: Bridging between experiment and DFT calculations

In this work, the impact of the doping process on the photoluminescence emission of CaWO₄ as a function of the concentration of Eu³⁺ cation (0.01 mol%, 0.02 mol%, 0.04 mol%, 0.06 mol%, 0.08 mol%, and 0.10 mol%) is discussed in detail. Ca_1?xWO₄:xEu³⁺ samples were successfully synthesized by a simple co-precipitation method followed by microwave irradiation. The blue shift in the absorption edge confirms the quantum confinement effect and the band gap energy covers the range from 3.91 to 4.18 eV, as the amount of Eu³⁺ cations increases. The experimental results are sustained by first-principles calculations, at the density functional theory level, to decipher the geometry and electronic properties, thereby enabling a more accurate and direct comparison between theory and experiment for the Ca_1?xWO₄:xEu³⁺ structure.     

Relaxor behavior and superior ferroelectricity of Y2O3-doped (Ba0.98Ca0.02) (Ti0.94Sn0.04Zr0.02)O3 lead-free ceramics

To upgrade the electric properties of lead-free piezoceramics, (1–x)(Ba_0.98Ca_0.02Ti_0.94Sn_0.04Zr_0.02)O₃-xY₂O₃ (abbreviated as (1–x)BCTSZ-xY, x = 0 mol%, 0.02 mol%, 0.04 mol%, 0.06 mol%, 0.08 mol% and 0.1 mol%) ceramics were successfully synthesized by traditional solid-state sintering method. The phase structure and microstructure of ceramics were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and piezoresponse force microscopyeramics (PFM). The electric properties of ceramics were researched through piezoelectric, dielectric and ferroelectric test instruments. The results show that all samples have pure perovskite structure and favorable electric properties. The optimal electric properties which especially include superior ferroelectric properties are gained when Y₂O₃ content is 0.06 mol% (d₃₃ = 419 pC/N, k_p = 52%, T_c = 89.5 °C, ε_r = 26900, tanδ = 2.86%, P_r = 14.41 μC/cm², E_c = 1.8 kV/cm). Moreover, the temperature-dependent dielectricity of samples shows apparent relaxor behavior under different frequencies. The Curie–Weiss law further proves that all samples are typical relaxor ferroelectrics, and the relaxor degree of samples decreases with increase of Y₂O₃ content. In conclusion, Y₂O₃ plays a significant role in enhancing electric properties of BCTSZ ceramics.     

Study on Red Long-Time Luminescent Material Y2O2S:Eu,M (M = Mg,Ca, Sr,Ba)

The red long-time luminescent material Y₂O₂S:Eu³⁺, M (M = Mg, Ca, Sr, Ba) was prepared by high temperature solid-state method. The XRD result of the sample showed that the crystal phase was Y₂O₂S, which belong to hexagonal system, and no new crystal phase were by doping different amount of Mg, Ca, Sr, Ba. The excitation spectrum was a broad band within 200 × 400 nm region, the characteristic peaks of emission spectrum were located at 583, 595, 597, 617, 627, 707 nm. There was no marked change in excitation spectra, emission spectra and maximum of their wavelengths of the luminescent materials by doping with different ions. The luminescent intensity of the phosphors were stronger when the concentration of doping ions was Mg/Y = 6%, Ca/Y = 4%, Sr/Y = 8%, Ba/Y = 2.5%, respectively. Its sequence of luminescent intensity from high to low is Sr > Ba > Mg > Ca.