Probing lattice defects in Sr2MgSi2O7:Eu2+,Dy3+

The Sr₂MgSi₂O₇:Eu²⁺,Dy³⁺ materials were prepared with a solid state reaction and their microscopic structure (at 295 K only) and luminescence were studied at selected temperatures between 150 and 295 K. Undisturbed Sr crystal planes were common in the TEM images of the undoped Sr₂MgSi₂O₇ material, whereas with Eu²⁺ doping more disturbed planes were observed even in the nanometer scale. With Dy³⁺ co-doping, a large number of small lattice domains created by the discontinuities in the crystal structure was observed. The domains with different orientations seem to be centered around point defects. The decay curves of Sr₂MgSi₂O₇:Eu²⁺,Dy³⁺ showed fast (ms scale) persistent luminescence. The intensity of persistent luminescence increased considerably between 200 and 250 K while remaining constant in the ranges of 150–200 and 250–295 K. The changes were used to study the depth of the traps. In general, Dy³⁺ co-doping was found to deepen the traps.     

蓝色长余辉材料Sr2MgSi2O7：Eu2+,Dy3+及其基质的VUV-UV激发特性

Sr₂MgSi₂O₇:Eu²⁺,Dy³⁺是一种有效的蓝色长余辉材料,采用高温固相法合成了Sr₂MgSi₂O₇,Sr₂MgSi₂O₇:Dy³⁺,Sr₂MgSi₂O₇:Eu²⁺及Sr₂MgSi₂O₇:Eu²⁺,Dy³⁺,利用同步辐射研究了它们的VUV-UV激发特性.在真空紫外光激发下,在基质中发现了稍弱的位于385nm的发射带,在双掺杂的样品中,除了Eu²⁺的4f5d→4f发射带(465nm)外,还观察到了575nm处的发射峰;通过和Dy³⁺单掺杂样品的发射谱比较,发现它是来自于Dy³⁺的4f-4f(⁴F_9/2→6H_13/2)跃迁.在它们的激发谱上可以看出Dy³⁺与基质发射的有效激发均处于真空紫外区,在近紫外及可见区激发下未见到它们发光.另外在Sr₂MgSi₂O₇:Eu²⁺,Dy³⁺中观察到Dy³⁺的发射也说明了Dy³⁺在该类长余辉材料中不仅作为陷阱用来延长余辉,而且也以发光中心形式存在于基质中.     

长余辉材料Sr2MgSi2O7：Eu2+,Dy3+中稀土离子的发光特性

利用同步辐射光源(德国HASYLAB实验室的SUPERLUMI实验站)和真空紫外激光(157.6nm)对新型蓝光发射长余辉材料Sr₂MgSi₂O₇:Eu²⁺(0.2%),Dy³⁺(8%)进行了光谱研究。在170nm同步辐射光源激发下,观察到对应Eu²⁺:5d-4f跃迁的477nm发射带和对应Dy³⁺:4f-4f跃迁的两组线谱发射,其中只有来自Eu²⁺的5d-4f发射对长余辉光谱有贡献。在157.6nm激光激发下,除了上述发射外,还明显观察到对应Eu³⁺的红色线谱(590,614,626nm)。结合这些光谱特性,对Sr₂MgSi₂O₇:Eu²⁺,Dy³⁺中稀土离子的发光特性以及长余辉发光机理进行了讨论,并提出了Eu²⁺充当空穴陷阱的可能性。     

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   

Sr1-xBaxAl2O4：Eu2+ , Dy3+磷光体的 制备及其发光特性

采用高温固相法在1 350 ℃弱还原气氛下制备了Sr_1-xBa_xAl₂O₄ : Eu²⁺ ,Dy³⁺ (x=0,0.2,0.4,0.6,0.8,1.0)长余辉材料,并对其微观结构和发光特性进行了分析。X射线衍射结果表明,当钡的掺杂摩尔分数x＜0.4时,样品晶体结构为SrAl₂O₄单斜晶系结构;当x≥0.4时,样品晶体结构为BaAl₂O₄六角晶系结构;而且随着钡对锶的取代,两种晶体结构的晶格常数都发生了一定程度的膨胀。光致发光测试结果表明,当x从0增大到1.0时,样品发射波长峰值也相应由515 nm逐渐蓝移到494 nm。通过热释光谱测试表明, SrAl₂O₄结构的样品的热释光峰所对应的温度比BaAl₂O₄ 结构的要高,且对应SrAl₂O₄结构的样品的余辉时间更长,初始亮度更高。     

Yellow persistent luminescence of Sr2SiO4:Eu2+,Dy3+

This paper reports the photoluminescence and afterglow of Sr₂SiO₄ doped with Eu²⁺ and Dy³⁺. Factors governing the formation of the monoclinic or orthorhombic phase of this ortho-silicate are described and the impact of the crystallographic modification on the luminescence and afterglow under UV and VUV excitation are discussed and insight in factors limiting the efficiency of this yellow afterglow material is given.     

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.     

Sr3SiO5:Eu2+和Sr3SiO5:Eu2+, Dy3+荧光粉的黄色长余辉性质

用高温固相法制备了Sr3SiO5:Eu2 和Sr3SiO5:Eu2 , Dy3 荧光粉.在紫外光辐照后, Sr3SiO5:Eu2 和Sr3SiO5:Eu2 , Dy3 荧光粉具有明亮的黄色长余辉,源于Eu2 的4f65d - 4f7的跃迁.紫外光激发停止后,Sr3SiO5:Eu2 的余辉时间是4 h以上.余辉衰减曲线和热释光曲线说明了引入Dy3 离子可以产生大量的深陷阱和浅陷阱.产生的深陷阱使余辉时间延长到6 h以上.由热释发光曲线,根据热释光的通用级公式拟合了陷阱深度.Sr3SiO5:Eu2 和Sr3SiO5:Eu2 , Dy3 荧光粉是有应用前景的黄色长余辉材料.     

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。     

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.     

Persistent luminescence and synchrotron radiation study of the Ca2MgSi2O7:Eu2+,R3+ materials

The tetragonal ${\mathrm{Ca}}_2{\mathrm{MgSi}}_2{\mathrm{O}}_7$:${\mathrm{Eu}}^{2+},{\mathrm{R}}^{3+}$ persistent luminescence materials were prepared by a solid state reaction. The UV excited and persistent luminescence was observed in the green region centred at 535 nm. Both luminescence phenomena are due to the same ${\mathrm{Eu}}^{2+}$ ion occupying the single ${\mathrm{Ca}}^{2+}$ site in the host lattice. The ${\mathrm{R}}^{3+}$ codoping usually reduced the persistent luminescence of ${\mathrm{Ca}}_2{\mathrm{MgSi}}_2{\mathrm{O}}_7$:${\mathrm{Eu}}^{2+}$, which differs from the ${\mathrm{M}}_2{\mathrm{MgSi}}_2{\mathrm{O}}_7$:${\mathrm{Eu}}^{2+}$ $(\mathrm{M}=\mathrm{Sr},\mathrm{Ba})$ and ${\mathrm{MAl}}_2{\mathrm{O}}_4$:${\mathrm{Eu}}^{2+}$ $(\mathrm{M}=\mathrm{Ca},\mathrm{Sr})$ materials. Only the ${\mathrm{Tb}}^{3+}$ ion enhanced slightly the persistent luminescence. With the aid of synchrotron radiation, the band gap energy of ${\mathrm{Ca}}_2{\mathrm{MgSi}}_2{\mathrm{O}}_7$:${\mathrm{Eu}}^{2+}$ was found to be about 7 eV that is very similar to those of the ${\mathrm{M}}_2{\mathrm{MgSi}}_2{\mathrm{O}}_7$:${\mathrm{Eu}}^{2+}$ $(\mathrm{M}=\mathrm{Sr},\mathrm{Ba})$ materials. Thermoluminescence results suggested that the ${\mathrm{R}}^{3+}$ ions might act as electron traps, but only the TL peaks created by ${\mathrm{Tm}}^{3+}$ and ${\mathrm{Sm}}^{3+}$ can be found in the temperature range accessible. Lattice defects (e.g. oxygen vacancies) are also important, since the same main thermoluminescence peak was observed at about $100{}^{\circ }\mathrm{C}$ with and without ${\mathrm{R}}^{3+}$ codoping.     

Silane-based wet and plasma coating on SrAl2O4:Eu2+, Dy3+ phosphor for surface modification

To date, organizations in many countries have tried persistent phosphors to apply in the field of safety facilities such as road striping and signs to improve visibility. However, the road facilities were usually exposed to harsh conditions such as pouring and wearing. Therefore, the surface coating and modifications of the phosphor are researched to improve the stability and adhesivity for binder material. Herein, we report the comparison of wet and plasma coating method for surface modification. Three kinds of silane functional materials for coating agent with different characteristic was chosen. From the results, we could confirm that the uniformity of the coating is better in the case of the plasma process. And the plasma-coated phosphor with the coating agent which has long carbon chain maintains the luminescence intensity over 50% after soaking in water for 48h, despite the pristine phosphor almost loses the luminescence characteristics occurring the phase transition.     

激发波长和Eu2+的掺杂量对Sr4 Al14 O25:Eu2+,Dy3+发光性能的影响

采用溶胶-凝胶法在低温、还原气氛下制备了长余辉发光材料Sr4 Al14O25:Eu2+,Dy3+.用X射线粉末晶衍射对其进行了物相鉴定,表明在1200℃已经得到纯相的Sr4Al14O25产物.研究了铕和锶的比值、激发光波长对所制备的Sr4 Al14O25:Eu2+,Dy3+发光性能的影响并对其影响机理进行了探讨.样品的发光性能测试结果表明:采用溶胶-凝胶法制备长余辉发光材料Sr4Al14O25:Eu2+,Dy3+,其灼烧温度比高温固相法灼烧温度低;激发光谱向长波方向延伸时,在488 nm处发射峰增强,在410 nm处发射峰减弱;在一定范围内发光强度随着Eu2+量的增加而增强,Eu2+的最佳掺杂量为0.007,Eu2+的掺杂量超过0.007时会发生浓度猝灭.     

Dose effects on the long persistent luminescence properties of beta irradiated SrAl2O4:Eu2+, Dy3+ phosphor

The SrAl₂O₄:Eu²⁺, Dy³⁺ is a phosphor characterized by a long persistent luminescence (PLUM) when it is excited with UV–VIS light and ionizing radiation. In this paper, we study the PLUM behavior as a function of beta irradiation dose in the 0–650 Gy range with a fixed dose rate of 5 Gy/min. The PLUM intensity showed a complex decay behavior, exhibiting a near linear response in the 0–1.7 Gy low dose range and gradually increasing up to 160 Gy. The PLUM reached the saturation for higher doses (>275 Gy) with a slight decrease in the range of 300–650 Gy. In addition, a systematic PLUM enhancement was produced after a thermal cleaning procedure and irradiation at RT in a series of 10 cycles. The observed phenomenon may be related to a radiation-induced process of charge trapping accumulation, which is triggered by thermal stimulation during the irradiation stage. It improves the luminescent characteristics of SrAl₂O₄:Eu²⁺, Dy³⁺ phosphors rendering them suitable for permanent display and illumination devices.     

Preparation and Properties of Sr3B2O6:Dy3+, Eu3+ White Phosphors Using the High-Temperature Solid-State Method

Journal of Applied Spectroscopy - Sr3B2O6:Dy3+, Eu3+ single-matrix white-light-emitting materials are prepared using the high-temperature solid-state method. The microstructure, emission spectrum,...     

Eu3+掺杂的Sr2CeO4发光材料的光致发光研究

利用高温固相反应法制备了Eu3+掺杂的Sr2CeO4样品,并对其吸附水前后的光谱特性进行了研究.结果发现,对于刚制备的Sr2-xEuxCeO4+x/2样品, 在Ce4+-O2-的电荷迁移激发中,只有强激发带(～35700cm-1)与Eu3+离子间存在能量传递,而弱激发带 (～29400cm-1)只是引起Ce4+-O2-的电荷迁移发射;在Sr2-xEuxCeO4+x/2样品吸附水后,Eu3+的线状吸收跃迁强度显著增加, Ce4+-O2-两个激发带均向Eu3+离子传递能量. Ce4+-O2-强激发带通过交换作用向Eu3+离子传递能量,而弱激发带与Eu3+离子间的能量传递机理是非辐射多极子近场力的相互作用.     

SrAl2O4:Eu2+,Dy3+的上转换发光特性

铕镝共掺的铝酸锶是一种新型的绿色长余辉荧光材料 ,经可见 -紫外光激发后 ,能发出超长时间的余辉。本文首次用 980nm的红外激发光源激发SrAl2 O4 :Eu2 ,Dy3 磷光体后 ,在室温下观测到了SrAl2 O4 :Eu2 ,Dy3 的绿色上转换荧光。并测得了其上转换荧光光谱图。与其正常的荧光光谱图相比 ,两者的峰形及波峰的位置有很大的差异 ,这预示着两者有不同的发光机理 ,并就其发光机理进行了初步的探讨。所用的样品经高温固相法合成后 ,用XRD表征。两种荧光光谱用荧光光谱仪测定。     

Ca_2MgSi_2O_7:Eu~(2+)绿色发光粉的低温合成及光致发光

采用CaCl2作助熔剂同时又作反应物,利用固相法在碳还原气氛下合成了Ca2MgSi2O7:Eu2+发光粉,确定其最佳的合成条件为按CaCO3、Mg(OH)2、SiO2、CaCl2的量的比1.5:1:2:2.4称取原料,烧结温度为900℃,烧结时间为3h。合成的样品可被360～480nm的光有效激发,得到发射峰值位于529nm的绿光。该发光粉Eu2+的最佳掺杂摩尔分数为0.02。与高温法相比,低温法制备的Ca2MgSi2O7:Eu2+发光粉激发光谱形状表现出一些差别,并且发射光强度显著增强,低温制备的Ca2MgSi2O7:0.02Eu2+的发射强度是高温制备样品的261%。