Preparation and luminescence characteristics of Eu^(2+) activated silicate phosphor

This paper synthesizes the Sr2SiO4：Eu^2＋ phosphor by high temperature solid-state reaction. The emission spectrum of Sr2SiO4 ： Eu^2＋ shows two bands centred at 480 and 547 nm, which agree well with the calculation values of emission spectrum, and the location of yellow emission of Sr2SiO4 ： Eu^2＋ is influenced by the Eu^2＋ concentration. The excitation spectrum for 547 nm emission has two bands at 363 and 402 nm. The emission spectrum of white light emitting diodes （w-LEDs） based on Sr2SiO4 ： Eu^2＋ phosphor ＋ InGaN LED was investigated.

Structure and Luminescence Characteristics of Europium Activated Strontium Silicates Sr(Eu,Bi)SiO_3 and Sr(Eu,Bi)_2SiO_4

Sr2SiO4∶Eu 3+ ,Bi 3+ and SrSiO 3∶Eu 3+ ,Bi 3+ samples were synthesized at high temperature and high pressure. The effect of high pressure on the structure and luminescence properties of the samples were studied. As a comparison, the samples were also prepared by the method of sol-gel at high temperature and atmospheric pressure. The SrSiO 3∶Eu 3+ ,Bi 3+ prepared at atmosphere has a hexagonal phase structure; in the pressure range of 2 34-4 10 GPa, it is transformed into a pseudo-orthorhombic structure(monoclinic), and in the pressure range of 4 10-4 15 GPa, the structure change of Sr 2SiO 4∶Eu 3+ , Bi 3+ has not been observed, it maintains the monoclinic structure of the samples synthesized at an atmospheric pressure. High pressure makes the luminescence properties of the samples changed obviously. The intensity and the relative quantum luminescent efficiency decrease, the half-width increases obviously and the red shift occurs. The changes of the luminescence properties result from the pressure-induced changes of the crystal structures.

Luminescence characteristics of Eu^(3+) activated borate phosphor for white light emitting diode

In this paper, the Sr3Y2 （BO3）4 ：Eu^3＋ phosphor was synthesized by high temperature solid-state reaction method and the luminescence characteristics were investigated. The emission spectrum exhibits one strong red emission at 613 nm corresponding to the electric dipole 5^Do-7^F2 transition of Eu^3＋ under 365 nm excitation, this is because Eu^3＋ substituted for Y^3＋ occupied the non-centrosymmetric position in the crystal structure of Sr3Y2（BO3）4. The excitation spectrum indicates that the phosphor can be effectively excited by ultraviolet （254 nm, 365 nm and 400 nm） and blue （470 nm） light. The effect of Eu^3＋ concentration on the red emission of Sr3Y2（BO3）4 ：Eu^3＋ was measured, the result shows that the emission intensities increase with increasing Eu^3＋ concentration, then decrease. The Commission Internationale del＇Eclairage chromaticity （x, y） of Sr3Y2（BO3）4 ：Eu^3＋ phosphor is （0.640, 0.355） at 15 mol% Eu^3＋.

Luminescence Characteristics and Energy Transfer Machanismof LaOBr:Tb^(3+) (Dy^(3+))

The rare earth luminescence materials LaOBrfTb3+(Dy3+) were synthesized at high temperature,and the structure and luminescence characteristics were studied. The co-doping Dy3+ may make the energy of 5D3 of Tb3+ transfer to 5D4 level, which makes the emission of 5D4-7FJ (J=0,1... 6), specially of 5D4-7F5, enhance obviously, and the total brightness is increased by about 40% in comparison with the samples without Dy3+ cations, as a result of the energy transfer of dipole-dipole interaction.

3-27 Characteristics of Luminescence of N Ion Irradiated LED

In the present work, the LED chip was irradiated by using 59.6 MeV N ions in a terminal chamber of theSector-focused cyclotron (SFC) in the National Labortary of Heavy-ion Accelerators in Lanzhou. The 63 MeV Nions penetrated through a gold foil and scattered in a large area. The energy of ion was reduced to 59.6 MeV afterscattering of the gold foil. The LED was provided by the Semiconductor Lighting Center in Institute of Semiconductorin Beijing. The luminences of the LED before/after irradiation were tested through a integrating sphere inSemiconductor Lighting Center in Institute of Semiconductor in Beijing. The luminance was tested under a currentof 350 mA. Fig. 1 shows the relationship between the luminences and the irradiation fluences. The irradiation led

SPECTRAL VARIATION AND CHARACTERISTICS OF LOW VALENCY RARE EARTH IONS IN COMPLEX OXIDESⅢ.EFFECT OF THE CRYSTAL ENVIRONMENT AND CHEMICAL FACTORS ON LUMINESCENCE PROPERTIES OF EUROPIUM (Ⅱ) ION

In this paper,the influence of crystal-field on the Luminescence properties of Eu^(2+) in complex oxides are studied theoretically by using purely electrostatic model,the dependence of the 4f^65d levels on Eu-O bond distance is given.Quantum chemistry calculation shows that the splitting extent of 4f^65d energy band in cubic or in octahedral fields will be inversely proportional to R^5,where R is the distance of Eu^(2+) to oxygen ligand.The value of R affects slightly the location of the centre of 4f^65d energy band.According to the exper- imental spectrum data,we have discussed the influence of the host chemical composition,the replaced sites of Eu^(2+) and degree of covalency of Eu-O bond on luminescence properties of Eu^(2+).Some regularity of fluorescence spectrum was observed. In alkali-alkaline earth-phosphates,the splitting extent of 4f^65d band (△E) becomes smaller as the Eu-O bond distance (R) increases.In Na_(3-x)(PO_4)_(1-x)(SO_4)_x and Na_(2-x)CaSi_(1-x)P_xO_4 hosts,d-d emission peak of Eu^(2+) will shift to shorter wavelength with the increase of x's value. The crystal structure data show that Eu^(2+) in K_2Mg_2(SO_4)_3 is affected more strongly by crystal-field and covalancy than in KMgF_3,so K_2Mg_2(SO_4)_3:Eu^(2+) emits blue light (E_(em)~m=400nm) and KMgF_3:Eu^(2+) produces ultraviolet fluorescence.

Luminescent characteristics of Ba_3Y_2(BO_3)_4:Eu^(3+) phosphor for white LED

The Ba3Y2（BO3）4：Eu^3＋ phosphor was synthesized using a high temperature solid-state reaction method and the luminescent characteristics were investigated. The emission spectrum exhibited one strong red emission at 613 nm, corresponding to the electric dipole 5D0-TF2 transition of Eu^3＋, under 365 nm excitation. The excitation spectrum of 613 nm indicated that the Ba3Y2（BO3）n：Eu^3＋ phosphor was effectively excited by ultraviolet （UV） （254, 365 and 400 nm） and blue （470 nm） light. The effect of Eu^3＋ concentration on the 613 nm emission of the Ba3Y2（BO3）n：Eu^3＋ phosphor was measured. The results showed that the emission intensity increased with increasing Eu^3＋ concentration, and then decreased. The CIE color coordinates of Ba3Y2（BO3）4：Eu^3＋ phosphor were x=0.641 and y=0.359 at 15 mol.% Eu^3＋.

Effects of SrO/Al_2O_3 Molar Ratio on the Luminescent Characteristics of Rare-Earth Strontium Aluminate Phosphors

The study on the effects of SrO/Al 2O 3 molar ratio on the crystalline phases and photoluminescence characteristics of strontium aluminate phosphors co-activated with Eu 2+ and Dy 3+ were conducted by X-ray powder diffractometry, fluorescence spectrometer and photometer. The strontium aluminate luminescent materials with different SrO/Al 2O 3 molar ratio emit the visible lights with different color tone after removal of excitation. The peak wavelengths of the emission spectra drift in the direction of short wave, the quantity of Sr 4Al 14O 25 crystalline phase increases and the afterglow time lengthens with the SrO/Al 2O 3 reduction. The results show that when the SrO/Al 2O 3 molar ratio is near 1, the photoluminescence materials have high luminescent intensity, and when it is near 0.75, they have long afterglow time. However, when SrO/Al 2O 3 molar ratio is more than 1, the luminescent materials appear strong alkaline in water solution; when SrO/Al 2O 3 molar ratio is much less than 0.75, the samples need a higher temperature to be sintered.

Luminescent Properties and Decay Characteristics of CaS: Mn^(2+) Phosphor

Mn2+ has been synthesized by a new sulfurizing flux method, and the phosphors prepared in this way is relatively stable in water. The fluorescent spectra of CaS host and CaS: Mn2+ have been measured at room temperature. The luminescent centers formed by O2- ions may be responsible for the host’s blue - green emission. The complete disappearance of this emission in CaS: Mn2+ system confirms that there exists efficient energy transfer from the host to the Mn2+ centers. The decay characteristics have been performed. The photoluminescence decay of CaS: Mn2+ consists of slow and fast components due to the single and paired Mn2+ centers, respectively.

Preparation and Luminescence Behavior of CaSiO_3∶Eu^(3+)(Bi^(3+))

CaSiO3：Eu0.08^3＋Bi0.002^3＋ with a monoclinic perovskite structure was synthesized by using sol-gel method, and its luminescence characteristics were investigated. From the excitation spectrum, it can be seen that the main peaks located at 238,396,415,437 and 359 nm correspond to the charge-transfer band of Eu^3＋-O^2- , the absorption transitions of ^7F0.1→^3L6, ^7F0→^5D3, ^7F1→^5D3 of Eu^3＋ ions, and ^3P1→^1S0 of Bi^3＋ ions, respectively. When the samples were excited with a light of wavelength 359 or 395 nm, it can be seen from the emission spectrum that the electronic dipole transition located at 609 nm corresponding to ^5D0→^7F2 of Eu^3＋ ions was stronger than the magnetic dipole transition located at 587 nm corresponding to ^5D0→^7F1 of Eu^3＋ ions, which shows that more Eu^3＋ ions were located in nonreversion center lattices. The energy transfer from Bi^3＋ ions to Eu^3＋ ions in the phosphor was also discussed. The results show that Eu^3＋ ions could be well sensitized by ^3＋ions, and the energy-transfer pattern between Bi^3＋ ions and Eu^3＋ ions was resonance energy transfer.

Preparation and luminescence characteristics of Sr_3SiO_5:Eu^(2+) phosphor for white LED

The Sr3SiO5:Eu2+ phosphor was synthesized by high temperature solid-state reaction. The emission spectrum of Sr3SiO5:Eu2+ shows two bands centered at 487 and 575 nm, which well agree with the theoretic values of emission spectrum. The excitation spectrum for 575 nm emission center has several excitation bands at 365, 418, 458 and 473 nm. And the results show that the emission spectrum of Sr3SiO5:Eu2+ is influenced by the Eu2+ concentration. The relative emission spectra of the white-emitting InGaN-based YAG:Ce3+ LED and Sr3SiO5:Eu2+ LED were investigated. The results show that the color development of InGaN-based Sr3SiO5:Eu2+ is better than that of InGaN-based YAG:Ce3+, and the CIE chromaticity of InGaN-based Sr3SiO5:Eu2+ is (x=0.348, y=0.326).

Study on luminescence characteristics of blue OLED with phosphor-doped host-guest structure

In this study,we design and fabricate phosphor-doped host-guest structure organic light-emitting diodes(OLEDs),where the blue-ray iridium complex electrophosphorescent material FIrpic acts as object material.Properties of the device can be accommodated by changing the host materials,dopant concentration and thickness of the light-emitting layer.The study shows that the host material N,N'-dicarbazolyl-3,5-benzene(mC P)has a higher triplet excited state energy level,which can effectively prevent FIrpic triplet excited state energy backtracking to host material,thus the luminous efficiency is improved.When mC P is selected as the host material,the thickness of the light-emitting layer is30 nm and the dopant concentration is 8 wt%,the excitons can be effectively confined in the light-emitting region.As a result,the maximum current efficiency and the maximum brightness of the blue device can reach 15.5 cd/A and7 196.3 cd/m^2,respectively.

砂岩型铀矿土壤热释光特性及测量流程优化

砂岩型铀矿因其矿体埋深大、辐射信息被掩盖,传统放射性物探技术难以满足其勘查需求。本文基于天然土壤热释光测量技术,对砂岩型铀矿表层沉积岩样品的热释光特性进行了深入研究,明确了稳定热释光信号主要来源于长石与石英矿物成分。通过甄选稳定的热释光信号,并基于200、237、263、325、375℃下稳定的热释光信号建立了适用于砂岩型铀矿勘查的优化测量流程。针对长石和石英混合矿物成分,测量流程选取的热释光信号在0~600 Gy辐照剂量范围内具有较好的剂量响应特性,且等效剂量测量值相对误差小于7%,兼顾了测量效率与准确性,可为天然土壤热释光法应用于砂岩型铀矿勘探提供技术参考。

Synthesis,structure,and luminescence properties of melilite Dy^(3+):Lu_(x)CaLa_(0.98-x)Ga_(3)O_(7) phosphors for use in yellow light-emitting devices

Dy^(3+) and Lu^(3+) co-doped CaLaGa_(3)O_(7) phosphors were prepared via high-temperature solid-phase reaction.The electronic structures of LuxCaLa_(0.98-x)Ga_(3)O_(7) were investigated by the first-principles calculations.The influence of Lu^(3+) on yellow light emission was studied using X-ray diffraction(XRD)and photoluminescence(PL) measurements.The XRD results indicate that compared to Dy^(3+):CaLaGa_(3)O_(7),the cell parameters of Dy^(3+):LuCaLaGa_(3)O_(7) tend to decrease,which is due to the smaller radius of Lu^(3+).When pumped by blue GaN laser diode(LD),the emission peaks of phosphors with different Lu^(3+)doping concentrations in the visible region are similar,with the strongest peak at 574 nm in the yellow light region,which is sensitive to human eyes.The optimal doping concentration of Lu^(3+) is confirmed to be1 at%,when all emission spectra and measured fluorescence lifetimes are taken into account.Moreover,the optimal phosphor composition Dy^(3+):Lu_(x)CaLa_(0.98-x)Ga_(3)O_(7)(x=0.01) has an internal quantum efficiency(IQE) of 46.94% and an external quantum efficiency(EQE) of 15.19%.Most notably,the prepared phosphor demonstrates excellent thermal stability and a high activation energy(0.203 eV).In addition,the International Illumination Commission color coordinates of the Dy^(3+):LuxCaLa_(0.98-x)Ga_(3)O_(7) phosphors are in the yellow light area.The above analysis indicates that the Dy^(3+):LuxCaLa_(0.98-x)Ga_(3)O_(7)(x=0.001)phosphor has promising application prospects in yellow light-emitting devices.

四川雪宝顶白钨矿的矿物学及发光特征

本文通过对四川雪宝顶地区(瀑口梁、三道气、水晶镇、五铢堂)的白钨矿进行常规矿物学测试、LA-ICP-MS及光致发光光谱(PL光谱)测试,旨在获得其化学成分、矿物学与发光特征。通过高温固相法合成掺杂不同比例Sm、Eu、Dy元素的CaWO_(4)多晶,分析其光致发光光谱以探究Sm、Eu、Dy元素对其红色荧光的影响。结果显示,在中波紫外光(310 nm)照射下,四川雪宝顶地区白钨矿的荧光颜色有分区性,为红色和淡黄色;化学成分测试结果显示,样品含有Sr、Nb、Mn、Mo、稀土元素(REE)等微量元素,整体含有较高的REE总量(335.8-2243.0μg/g)和Sr元素(126.3~5188.2μg/g),在淡黄色荧光区域富集的Nb、Mn、Mo元素,说明白钨矿中Mn、Mo、Nb可提高作为激活剂的三价稀土离子(RE^(3+))的荧光发射强度。PL光谱测试表明,其红色荧光主要是Sm^(3+)、Eu^(3+)的贡献,其次还有Dy^(3+)、Tb^(3+)、Pr^(3+)的影响,淡黄色荧光主要是由Dy^(3+)导致,其次还有Sm^(3+)、Eu^(3+)的影响。本文通过分析合成白钨矿PL光谱得出,Dy^(3+)是Sm^(3+)、Eu^(3+)的敏化剂,Dy^(3+)对Sm^(3+)的荧光发射强度增强的更明显,尤其是Sm^(3+)的^(4)G_(5/2)→^(6)H_(7/2)跃迁(580~620 nm),在天然白钨矿中表现为Dy^(3+)阻碍了Sm^(3+)→Eu^(3+)的能量传递以及部分样品中Sm^(3+)最强发射峰从^(4)G_(5/2)→^(6)H_(9/2)跃迁(630~660 nm)变为^(4)G_(5/2)→^(6)H_(7/2)跃迁(580~620 nm)。

Ultra-weak bioluminescence and vigour of irradiated rice

Detection of the irradiation dose and the vigour of irradiated rice based on the ultra-weak luminescent analysis is one of the promising analytical detection methods.Rough rice and head rice flour were used in this research for ultra-weak luminescent analysis.The bioluminescence intensity of the rough rice was different at varying irradiation doses and storage time.The trend of the differences was consistent with the germination rates of the irradiated rough rice.The changes of the bioluminescence intensity and the germination rate of the irradiated rough rice at diverse irradiation doses and storage time were due to the damage to the rice embryo caused by irradiation and the self-repair function of the embryo during storage.As a result,the ultra-weak luminescent analysis cannot detect the dose of the irradiation treatment on rice,but it can be used to detect the vigour of the irradiated rice.Experimental results show that the irradiation dose has a highly significant effect on the bioluminescence intensity of the rough rice flour when sucrose was added.

原子层沉积Al_(2)O_(3)钝化对InAs/InGaAsSbⅡ类超晶格发光特性的影响

提出一种基于干法刻蚀与原子层沉积相结合的钝化方法,采用干法刻蚀去除InAs/InGaAsSb超晶格表面及端面固有的氧化层,利用原子层沉积Al_(2)O_(3)薄膜钝化刻蚀表面,对钝化前后光致发光光谱的表征研究其发光性能与长期稳定性。处理后超晶格的As 3d谱中As-O键相关的峰消失表明其表面的氧化物被有效去除。样品的发光强度与激发光功率之间的拟合系数α从1.17减小为1.02,表明激子主导的发光占比增加。连续五天的红外光谱测试发现,处理后样品发光强度降低为原来的89%,而未处理样品的发光强度降低为原来的76%,表明处理后超晶格表现出更好发光稳定性。本研究为提升InAs/InGaAsSb超晶格性能、促进其光电探测领域的应用提供参考。

Sb^(3+)/Bi^(3+)掺杂对Cs_(2)ADyCl_(6)(A=Li,Na,K)发光性能的影响

A2B′BCl_(6)型双钙钛矿因其极强的空气稳定性和出色的光学特性而被应用于发光材料。以Cs^(+)作为A^(+),Dy^(3+)替代Pb^(2+),Cl^(-)作为卤素制备新的镝基钙钛矿纳米晶体Cs_(3)DyCl_(6),使用Li、Na、K离子替代式掺杂合成Cs_(2)ADyCl_(6)(A=Li,Na,K)非铅体系钙钛矿材料,通过掺杂Sb^(3+)/Bi^(3+)作为激发剂实现了不同发光性能的调控。结果表明:Cs_(2)NaDyCl_(6)发射曲线更加平滑且在蓝光与黄光区域均可实现发射,表现出优异的光学特性;通过Sb^(3+)/Bi^(3+)掺杂,双钙钛矿的光学特性得到显著提升,Na^(+)和Sb^(3+)的共同作用可以使钙钛矿材料发光产生蓝移,而Na^(+)与Bi^(3+)的共同作用则可以使其发光产生红移。

三联吡啶苯桥连β-二酮配体调控3d-4f能量传递及单分子白光研究

设计并制备了三联吡啶单、双和三苯桥连β-二酮配体(SL3、DL3和TL3)及其3d-4f配合物(SL3-Zn-Eu、DL3-Zn-Eu和TL3-Zn-Eu)。研究发现,SL3-Zn-Eu和DL3-Zn-Eu在紫外激发下通过三重态能量传递敏化Eu3+的特征红光,两者色度坐标均为(0.67,0.33),主要原因是3d和4f中心距离更近,更有利于3d-4f的能量传递。然而,TL3-Zn-Eu结构中3d和4f中心距离更远,且随着桥连苯环数量的增加导致桥连苯平面扭曲,使3d→4f能量传递速率减低和单重态能量传递敏化Eu^(3+)发光。从荧光光谱中可以检测到Eu^(3+)特征红光和TL3-Zn的残余青光,其发光颜色落在白光区域,色度坐标为(0.30,0.29)。总之,本文设计的3d-4f配合物随着桥连苯数的增加,可以改变分子共轭性和3d→4f间距离,从而调节能量传递效率和传递机制,获得单分子发射白光材料。

Sr_2SiO_4:Dy^(3+)材料制备及发光特性

采用高温固相法制备了Sr2SiO4:Dy3+发光材料.在365nm紫外光激发下,测得Sr2SiO4:Dy3+材料的发射光谱为一个多峰宽谱,主峰分别为486,575和665nm;监测575nm的发射峰,所得材料的激发光谱为一个多峰宽谱,主峰分别为331,361,371,397,435,461和478nm.研究了Dy3+掺杂浓度对Sr2SiO4:Dy3+材料发射光谱强度的影响.研究结果显示,随着Dy3+浓度的增大,黄、蓝发射峰比值(Y/B)也逐渐增大;随着Dy3+浓度的增大,575nm发射峰强度先增大后减小.加入电荷补偿剂Li+,Na+和K+均提高了Sr2SiO4:Dy3+材料的发射光谱强度,其中以Li+的情况最为明显.