Characterization and luminescence of Eu/Sm-coactivated CaYAl3O7 phosphor synthesized by using a combustion method

A novel red-emitting phosphor, CaYAl3O7 : Eu 3+ , Sm3+ , is synthesized by a combustion method at a low temperature (850℃), and the single phase of CaYAl3O7 is confirmed by powder X-ray diffraction measurements. The photoluminescence property results reveal that the red emission intensity of Eu3+ is strongly dependent on the Sm3+ concentration. Only the Eu 3+ luminescence is detected in the Eu 3+ -Sm3+ co-doped CaYAl3O7 phosphor with 393 nm excitation. However, under the characteristic excitation (402 nm) of Sm3+ , not only the Sm3+ emission but also the Eu 3+ emission are observed. A possible mechanism of the energy transfer between Sm3+ and Eu 3+ is investigated in detail.     

Synthesis, Characterization, Luminescence and Defect Centres in CaYAl3O7:Eu3+ Red Phosphor

CaYAl(3)O(7):Eu(3+) phosphor was prepared at furnace temperatures as low as 550°C by a solution combustion method. The formation of crystalline CaYAl(3)O(7):Eu(3+) was confirmed by powder X-Ray diffraction pattern. The prepared phosphor was characterized by SEM, FT-IR and photoluminescence techniques. Photoluminescence measurements indicated that emission spectrum is dominated by the red peak located at 618 nm due to the (5)D(0)-(7)F(2) electric dipole transition of Eu(3+) ions. Electron Spin Resonance (ESR) studies were carried out to identify the centres responsible for the thermoluminescence (TL) peaks. Room temperature ESR spectrum of irradiated phosphor appears to be a superposition of two distinct centres. One of the centres (centre I) with principal g-value 2.0126 is identified as an O(-) ion while centre II with an isotropic g-factor 2.0060 is assigned to an F(+) centre (singly ionized oxygen vacancy). An additional defect centre is observed during thermal annealing experiments and this centre (assigned to F(+) centre) seems to originate from an F centre (oxygen vacancy with two electrons). The F(+) centre appears to correlate with the observed high temperature TL peak in CaYAl(3)O(7):Eu(3+) phosphor.     

Effect of charge compensation on emission spectrum of Ca2SiO4:Dy3+ phosphor

The Ca2SiO4:Dy3+ phosphor was synthesized by the high temperature solid-state reaction method in air.The emission spectrum of Ca2SiO4:Dy3+ phosphor shows several bands at 486, 575, and 665 nm under the 365-nm excitation. The effects of Li+, Na+, and K+ on the emission spectrum of Ca2SiO4:Dy3a+ phosphor were studied. The results show that the emission spectrum intensity is greatly influenced by Li+, Na+,and K+. The charge compensation concentration corresponding to the maximum emission intensity is different with different charge compensations.     

The influence of Eu3+ doping on photoluminescent properties of red emitting phosphor YInGe2O7:Eu3+ by microwave assisted and conventional sintering method

This paper describes an investigation of the crystalline morphology and photoluminescent properties of YInGe₂O₇ powders doped with different Eu³⁺ concentrations using microwave assisted sintering and conventional sintering. X-ray powder diffraction analysis confirmed the formation of monoclinic YInGe₂O₇ structure as YInGe₂O₇:Eu³⁺ powders were sintered at 1200 °C in microwave furnace for 1 h, and the raw material phase of Y₂O₃ was observed when Eu³⁺ concentration was below 30 mol%. Scanning electron microscopy showed microwave assisted sintering results in smaller particle size and more uniform grain size distribution. In the photoluminescent (PL) studies, the concentration quenching effect was observed under the excitation at 393 nm, but not under the excitation at CTS band. The ⁵D₀→⁷F₂ transition (620 nm), exhibits a non-exponential decay behavior as YInGe₂O₇:Eu³⁺ powders were sintered by microwave with the Eu³⁺ concentration higher than 50 mol%.     

Photoluminescence in GdVO4:Bi3+, Eu3+ red phosphor

The doubly doped (Bi³⁺ and Eu³⁺) GdVO₄ powder is synthesized by hydrolyzed colloid reaction (HCR) technique and formation of material is confirmed by XRD measurement. Surface morphology has been studied by SEM measurement and the result shows uniform surface morphology. The average particle size observed by SEM is about 1 7m. The Fritsch particle sizer is used to study the particle size distribution. It distributes from O.15 to 3.57 7m. The small particle size (less than 5 7m) and the narrow particle size distribution, are the necessary requirements of good phosphor material. Photoluminescence result shows a narrow emission line of Eu³⁺ ion (4 nm FWHM) at 618 nm. The Eu³⁺ emission intensity is enhanced by a factor of five with the addition of small amount of Bi³⁺. The emission bands of VO₄^3- and Bi³⁺ partially overlap with the excitation band of Eu³⁺. The process of energy transfer from Bi³⁺ to Eu³⁺ is discussed here. The energy transfer probability is strongly dependent upon the Bi³⁺ and Eu³⁺ concentrations, with a maximum for 0.2 mol % of Bi³⁺ and 3 mol % of Eu³⁺. It drastically decreases for higher concentrations. For photoluminescent applications, the quantum efficiency (QE) of a phosphor material is an important parameter. The QE of GdVO₄:Bi,Eu(0.2,3) is 76%. The GdVO₄:Bi,Eu(0.2,3) material is proposed as an efficient photoluminescent phosphor.     

Crystalline-phase-dependent red emission behaviors of Gd2O3:Eu3+ thin-film phosphors

Gd₂O₃:Eu³⁺ luminescent thin films have been grown on Al₂O₃(0001) substrates using pulsed-laser deposition. The films grown at different deposition conditions showed different crystalline phases, surface morphologies and luminescent characteristics. Both cubic and monoclinic crystalline phases were observed for the Gd₂O₃:Eu³⁺ films, and the crystalline structure and the surface morphology of the films were highly dependent on the oxygen pressure and substrate temperature. The cubic system showed a higher luminescence than the monoclinic system. The luminescence characteristics were strongly influenced by not only the crystalline structure but also the surface morphology of the films. The photoluminescencebrightness data obtained from Gd₂O₃:Eu³⁺ films indicate that Al₂O₃(0001) is a promising substrate for growth of high-quality Gd₂O₃:Eu³⁺ thin-film red phosphor. In particular, the Gd₂O₃:Eu³⁺ films showed a much better photoluminescence behavior than a Y₂O₃:Eu³⁺ films with the same thickness. PACS 78.20.-e; 78.55.-m; 78.66.-w     

Nonradiative energy transfer from Mn2+ to Eu3+ in K2CaP2O7:Mn2+,Eu3+ phosphor

A series of color tunable phosphors K₂Ca_1?x?yP₂O₇:xMn²⁺, yEu³⁺ are synthesized by solid state reaction method. The energy transfer phenomenon from Mn²⁺ to Eu³⁺ has been observed in the Mn²⁺/Eu³⁺ codoped non-magnetic K₂CaP₂O₇ host, which was confirmed by PL spectra and decay curves. The Mn²⁺→Eu³⁺ energy transfer is controlled by quadrupole–quadrupole interaction between sensitizer and activator. The maximum efficiency of energy transfer is estimated to be 33% with x=0.125 and y=0.03 in K₂Ca_1?x?yP₂O₇:xMn²⁺, yEu³⁺ phosphor. The phosphors can emit light from green to yellow and eventually to orange under 400 nm excitation by changing the Mn²⁺/Eu³⁺ content ratio, indicating that K₂CaP₂O₇: Mn²⁺, Eu³⁺ would be potential candidates for use in lighting and displays applications.     

Eu3+ emission in SrAl2B2O7 based phosphors

Eu³⁺ doped SrAl₂B₂O₇ phosphors were fabricated by the wet method. The structures of the phosphors were characterized by XRD. The doping content of Eu³⁺ ions in SrAl₂B₂O₇:Eu³⁺ phosphors are 1%, 4%, 6%, 8%, 10% (molar fraction), respectively. Luminescence properties were analyzed by measuring the excitation and photoluminescence spectra. The luminescent properties of SrAl₂B₂O₇:Eu³⁺ phosphors are discussed. It is shown that from 4% to 6% of doping content of Eu³⁺ ions under 392 nm excitation in SrAl₂B₂O₇:Eu³⁺ phosphors is optimum.     

不同激发波长对Sr3Al2O6∶Eu2+,Dy3+红色长余辉发光材料发射光谱的影响

采用高温固相法合成了Sr3Al2O6∶Eu2+,Dy3+长余辉发光材料。用X射线衍射仪及荧光分光光度计对材料物相及光谱性能进行了分析。结果表明:所得样品为Sr3Al2O6的纯相,在360nm波长的激发下,得到波峰为537nm的宽带发射光谱;在468nm波长的激发下,得到波峰为590nm的宽带发射光谱;在波长为394nm的激发下,537和590nm的峰同时出现。根据晶格场效应和电子云膨胀效应,对不同激发波长对Sr3Al2O6∶Eu2+,Dy3+发射光谱的影响进行了解释。结果表明:在Sr3Al2O6∶Eu2+,Dy3+中发光中心因其5d能级劈裂幅度不同及4f65d1能带重心不同而导致发光颜色的不同。     

Eu3+激活的La2Mo2O9红色荧光粉的制备与性能

利用高温固相法制备了Eu³⁺掺杂的La₂Mo₂O₉红色荧光粉,并对这种荧光粉的结构及发光性质进行了研究。XRD结果表明,实验合成了单一立方相的La₂Mo₂O₉荧光粉体。该荧光粉的激发光谱由一宽带和一系列的锐峰组成;发射光谱由一系列锐峰组成,这些都与Eu³⁺的特征跃迁⁵D_J(J=0,1)和⁷F_J(J=1~4)相对应。结果表明该荧光粉可被395nm的紫外光和470nm的可见光有效激发,并发出峰值位于620nm左右的红光,亮度可达到传统红色荧光粉Y₂O₂S:Eu³⁺的1.5倍以上,这表明它可以作为蓝+黄模式白光LED的红色补光粉,也可以作为UV-LED激发三基色荧光粉体系中的红色荧光粉。研究了Eu³⁺的掺杂浓度以及不同助熔剂对样品发光性质的影响。Eu³⁺的摩尔分数为0.3时,发光强度达到最强。质量分数为3%的NH₄Cl作为助熔剂时效果最好。     

The effect of charge compensation by means of Na+ ions on the luminescence behavior of Sm3+-doped CaAl4O7 phosphor

Results of structural and spectroscopic measurements of Sm³⁺ doped calcium aluminates: Ca_1?xSm_xAl₄O₇ and Ca_1?2xSm_xNa_xAl₄O₇ (x=0.0005, 0.002, 0.01, 0.02, 0.03, 0.05) obtained by the modified Pechini method are presented. All samples yield intense orange–red emission under violet excitation (404.5 nm). Narrow bands corresponding to characteristic f–f intraconfigurational transition of Sm³⁺ in excitation and emission spectra were observed. The influences of the concentration of Sm³⁺ as well as charge compensation by co-doping with Na⁺ ions on the luminescent properties of the phosphor were investigated. Detailed analysis of the emission spectra of Sm³⁺ doped and Sm³⁺,Na⁺ co-doped CaAl₄O₇ powders proved that activator ions substitute Ca²⁺ in the host. Co-doping with Na⁺ ions enhanced greatly the intensity of the luminescence. Concentration dependencies of the intensity of luminescence and its decay kinetics proved the emission quenching at higher dopant contents due to cross-relaxation processes between Sm³⁺ ions. Fitting of the ⁴G_5/2 state fluorescence decay to the Inokuti–Hirayama model indicated dipole–dipole interaction as the dominant mechanism of the cross-relaxation processes.     

Dy含量对红色长余辉发光材料Sr3Al2O6:Eu2+,Dy3+性能的影响

采用溶胶凝胶法制备了Sr3Al2O6:Eu2+,Dy3+红色长余辉发光材料,利用X射线衍射仪对材料的物相进行了分析,结果表明,1200℃下制备的样品的物相为Sr3Al2O6,少量的Eu和Dy掺杂没有影响样品的相组成.采用荧光分光光度计、照度计测定了样品的发光特性.结果表明Sr3Al2O6:Eu2+和Sr3Al2O6:Eu2+,Dy3+的激发光谱均为激发峰位于473 nm的宽带谱.Sr3Al2O6:Dy3+的发射峰位于530.1 nm,对应于Dy3+代替Sr2+位置后基质中形成的施主-受主对Dy·Sr-V″Sr的重新组合.Sr3-0.02-yAl2O6:0.02Eu2+,yDy3+(0相似文献   

Synthesis and luminescence properties of a broad-band red phosphor Ca3Si2O7:Eu2+ for warm white light-emitting diodes

Single-phase broad-band red-emitting Ca₃Si₂O₇:Eu²⁺ phosphors, with photoluminescence features that qualify them as candidates for white light-emitting diodes applications, were successfully synthesized via a modified solid-state reaction method that employed H₃BO₃ as a flux. The phosphors produced have an intense broad red emission band, with a peak at 603 nm, a full width at half maximum of 110 nm, and color coordinates of (0.550, 0.438). Concentration quenching occurred at 0.01 mol Eu²⁺. The discussion of the results shows that Eu²⁺ ions should be accommodated at the Ca-sites of the lattice, dipole–dipole interactions should predominantly govern the energy transfer mechanism among them, and the critical distance between them is ～31 Å.     

Effect of charge compensation on emission spectrum of Ca2SiO4：Dy^3＋ phosphor

The Ca2SiO4：Dy^3＋ phosphor was synthesized by the high temperature solid-state reaction method in air. The emission spectrum of Ca2SiO4：Dy^3＋ phosphor shows several bands at 486, 575, and 665 nm under the 365-nm excitation. The effects of Li^＋, Na^＋, and K^＋ on the emission spectrum of Ca2SiO4：Dy^3＋ phosphor were studied. The results show that the emission spectrum intensity is greatly influenced by Li^＋, Na^＋, and K^＋. The charge compensation concentration corresponding to the maximum emission intensity is different with different charge compensations.     

溶胶-凝胶法制备Zn2SiO4:Eu3+红色荧光粉

采用溶胶-凝胶法在Zn2SiO4基质中掺杂Eu3+,合成了红色荧光粉Zn2SiO4:Eu3+.通过样品的X射线衍射光谱、红外光谱、扫描电镜以及光致发光光谱的测试和表征,研究了Zn2SiO4:Eu3+的内部结构和发光特性.扣描电镜结果显示样品为球状荧光粉,颗粒直径为1～3μm.在395 nm激发下,样品在613 nm处发射出很强的红光.结合荧光光谱,分析了样品的退火温度,Eu3+的浓度,电荷补偿剂Li+的浓度对样品发光强度的影响.研究发现,红色荧光粉Zn2SiO4:Eu3+的发光强度随退火温度的升高而增加,发光强度随Eu3+和Li+浓度的增加先增大后减小.     

Ba_2B_2P_2O_(10):Eu~(3+)材料的光谱特性

采用高温固相法合成了Ba2B2P2O10:Eu3+材料,并研究了材料的光谱特性。在400nm近紫外光激发下,材料的发射光谱由4组线状峰组成,峰值分别为600,618,627和660nm,分别对应Eu3+的5D0→7F1,7F2,7F3和7F4跃迁。研究了Eu3+掺杂浓度及电荷补偿剂对材料发射强度的影响,结果显示,随Eu3+掺杂浓度的增大,材料的发射强度增大,并未出现浓度猝灭效应,同时,添加电荷补偿剂可增强材料的发射强度。     

Luminescent properties of Eu2+and Dy3+ ions in Ba4Al2O7 phosphor for solid state lighting

In this paper we report the combustion synthesis of rare earth (RE=Eu, Dy) doped Ba₄Al₂O₇ phosphors. Prepared phosphors were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), CIE color co-ordinates and their photoluminescence (PL) properties were also investigated. In case of Ba₄Al₂O₇: Eu²⁺, the emission spectra show unique band centered at 495 nm, which corresponds to the 4f⁶5d¹→4f⁷ transition of Eu²⁺, and PL emission spectra of Dy³⁺ ion under 348 nm excitation give two bands centered at 478 nm (blue) and 575 nm (yellow), which originate from the transitions of ⁴F_9/2→⁶H_15/2 and ⁴F_9/2→⁶H_13/2 of Dy³⁺, respectively. The results indicate that the Eu²⁺ and Dy³⁺ activated Ba₄Al₂O₇ phosphor could find application in solid state lighting.     

Synthesis and luminescence properties of Na2Ba2Si2O7:Eu2+ phosphor

Green-emitting phosphor Na₂Ba₂Si₂O₇:Eu²⁺ has been synthesized by a conventional high-temperature solid-state reaction. The phase structure and luminescence properties are characterized by the X-ray powder diffraction, diffuse reflectance spectra, photoluminescence excitation and emission spectra, temperature-dependent emission spectra, respectively. It can be efficiently excited in the wavelength range of 325–400 nm and consists of a strong broad green band centered at about 501 nm, which is ascribed to 4f⁶6s⁰5d¹ → 4f⁷6s²5d⁰ transition of Eu²⁺. The critical quenching concentration of Eu²⁺ in the Na₂Ba₂Si₂O₇ host is about 0.8 mol % and corresponding quenching behavior is ascribed to be electric dipole–dipole interaction. Furthermore, the phosphor has good thermal stability property, and the activation energy for thermal quenching is calculated as 0.34 eV.     

Mg5SnB2O10:Eu3+,Bi3+—一种用于发光二极管的红色荧光粉的制备及其发光性能的研究

采用高温固相法成功合成了单一相的Eu³⁺,Bi³⁺共掺的Mg₅SnB₂O₁₀红色荧光粉,并通过X射线衍射、漫反射光谱、光致发光光谱等手段对该体系的结构及其发光特性进行了测试和研究.激发光谱表明,该荧光粉在393 nm呈现Eu³⁺的⁷Fo—⁵L₆特征激发,可以与用于发光二极管的近紫外芯片很好地匹配.在393 nm激发下,其发射光谱在591,612,701 nm处呈现Eu³⁺的⁵Do—⁷F₁,⁵Do—⁷F₂,⁵D₀—⁷F₄的特征发射.并且当固定Eu³⁺的浓度时,随着Bi³⁺含量的增加,发现Bi³⁺,Eu³⁺在这一体系中存在能量传递现象,系列样品发光强度大幅度提高.通过研究系列样品在不同Bi³⁺,Eu³⁺掺杂浓度下的发光性能,得出最佳样品为Mg_4.89Eu_0.1Bi_0.01SnB₂O₁₀,其积分强度达到了商用Y₂O₂S:Eu³⁺的1.1倍.