Ce:Lu2Si2O7闪烁晶体的结构和光谱特性

采用中频感应提拉法生长出Ce:Lu₂Si₂O₇（Ce:LPS） 晶体. 通过x射线粉 末衍射分析，晶体结构属单斜晶系的C2/m空间群. 光学显微镜下可观测到晶体的（110 ）解理. 在室温下测试了Ce:LPS晶体的吸收光谱、激发光谱和发射光谱. 结果表明，Ce:LPS 晶体的吸收峰只有两个，分别位于302和349 nm，且与激发峰的位置一致，归因于Ce³⁺ 的4f¹→5d¹跃迁的特征吸收所致. 发射光谱具有Ce^{3+< /sup>典型的双峰特征 ，经Gaussian多峰值拟合，带状谱是由384和407 nm两个发射峰叠加而成，且后者的强度明 显高于前者. 关键词： 2Si₂O₇')" href="#">Ce:Lu₂Si₂O₇ 提拉法 晶体结构 光学 特性}     

Lu2Si2O7∶Ce纳米晶的溶胶-凝胶法合成和闪烁性能

采用溶胶-凝胶法制备了Lu2Si2O7∶Ce纳米晶,利用X射线衍射(XRD)、扫描电镜(SEM)、荧光光谱仪、X射线激发发射谱仪对制备的Lu2Si2O7∶Ce纳米晶的晶相结构、微观形貌和光学性能进行了表征。结果表明,溶胶-凝胶法制备的Lu2Si2O7∶Ce前驱体在煅烧温度为1000℃时开始晶化,晶粒尺寸随着煅烧温度的升高而变大,1200℃煅烧2 h后的晶体颗粒均匀,分散性最优,平均晶粒尺寸约为28.9 nm,呈近球形;Lu2Si2O7∶Ce纳米晶的紫外吸收谱存在峰位分别为304 nm和350 nm两个吸收峰,源自于Ce^3+离子的4f→5d跃迁;光致发射谱和X射线激发发射谱都表现为典型的非对称双峰结构,归属于Ce^3+离子的5d^1→2F5/2和5d^1→2F7/2跃迁,Ce^3+离子的最佳掺杂浓度约为1%;荧光衰减时间约为37.2 ns,可满足高时间分辨X射线探测需要。     

Lu2Si2O7：Ce晶体的闪烁性能

用提拉法生长了Lu2Si2O7：Ce晶体，对该晶体的闪烁性能进行了研究。透射光谱表明，Lu2Si2O7：Ce晶体的吸收边比Lu2SiO5：Ce晶体向短波方向移动了25nm，使透光范围进一步拓宽。X射线发射光谱和UV激发发射光谱均具有典型的双峰特征，主峰在378nm。UV激发发射谱具有温度效应，即375K以上时，发光效率迅速降低；425K以上时，发光主峰位明显红移。衰减曲线符合单指数式衰减规律，常温下经UV激发后的衰减时间约为34ns。从曲线形态看，375K以下的衰减谱与室温下的几乎完全相同，拟合的结果在32．8～34ns之间；衰减时间的温度效应从375K开始显现，即随温度的升高，衰减时间有加速变短的趋势，到500K时缩短为6．72ns。热释光谱在488，553K处有两个热释光峰，但室温附近几乎观察不到热释光峰。     

Lu2Si2O7∶Ce晶体的闪烁性能

用提拉法生长了Lu2Si2O7∶Ce晶体,对该晶体的闪烁性能进行了研究。透射光谱表明,Lu2Si2O7∶Ce晶体的吸收边比Lu2SiO5∶Ce晶体向短波方向移动了25nm,使透光范围进一步拓宽。X射线发射光谱和UV激发发射光谱均具有典型的双峰特征,主峰在378nm。UV激发发射谱具有温度效应,即375K以上时,发光效率迅速降低;425K以上时,发光主峰位明显红移。衰减曲线符合单指数式衰减规律,常温下经UV激发后的衰减时间约为34ns。从曲线形态看,375K以下的衰减谱与室温下的几乎完全相同,拟合的结果在32.8～34ns之间;衰减时间的温度效应从375K开始显现,即随温度的升高,衰减时间有加速变短的趋势,到500K时缩短为6.72ns。热释光谱在488,553K处有两个热释光峰,但室温附近几乎观察不到热释光峰。     

Lu2SiO5:Ce透明薄膜改性及其发光性能

Lu2SiO5:Ce具有高密度、高光产额、快衰减等优点,是一种性能优异的新型X射线闪烁薄膜材料.本文采用溶胶-凝胶工艺和旋涂技术,以无机盐为原料、2-甲氧基乙醇为溶剂、聚乙二醇(PEG)为改性剂,在石英基片上成功制备出Lu2SiO5:Ce透明薄膜,较为详细地研究了PEG对该薄膜发光性能的影响.结果表明当采用浓度为12....     

银颗粒对Lu2O3:Eu薄膜光学性质影响

采用溶胶凝胶和提拉法制备了含有银颗粒的Lu2O3:Eu薄膜,利用X射线衍射,吸收光谱,光致发光光谱(PL)及荧光衰减光谱对其进行了表征,结果表明:所得材料在800℃下结晶完好,在发射光谱中观察到了银颗粒导致的Eu3 的发光增强效应,讨论了银颗粒对LU2O3:Eu薄膜发光性质的影响.     

Ce:YAG晶体和透明陶瓷的光学和闪烁性能

采用温梯法生长了Ce:YAG晶体和真空烧结法制备了Ce:YAG透明陶瓷,并对晶体和透明陶瓷的光学和闪烁性能进行了对比研究.Ce:YAG晶体和陶瓷都具有位于230,340和460 nm波段的Ce³⁺离子的特征吸收带和540 nm附近的发射峰,但Ce:YAG晶体同时存在296和370 nm的色心吸收,其发射峰位于398 nm,而透明陶瓷中不存在.Ce:YAG晶体和陶瓷的X射线荧光中均存在520 nm附近的Ce³⁺离子发射,但晶体中还存在由反格位缺陷引起的300 nm 关键词： Ce:YAG 闪烁晶体 透明陶瓷     

Ce3Rh3Si2和CeRh3Si2的磁性模拟和晶场效应研究

根据晶场理论,通过对D.Kaczorowski等人测量的磁化率倒数与温度关系曲线的模拟,得到了稀土化合物CeRh3Si2和Ce3Rh3Si2的晶场分裂能和相应波函数.对于CeRh3Si2和Ce3Rh3Si2,它们的第一激发能和总的激发能分别为176K,855K和77.5K,428K.计算表明,Kramers离子Ce3+在晶场效应的作用下,基态简并部分消除得到了三个双重态,模拟得到的化合物的磁化率倒数与温度关系曲线与实验曲线吻合较好.     

Mn2+∶BeAl2O4晶体的光谱特性

应用提拉法技术,采用BeO∶Al2O3∶MnO摩尔比为100∶99.85∶0.30的化学组分配比和二次化料过程,选用约60℃的固液界面温度梯度与1 mm/h生长速度等工艺参量,成功地生长出了Mn2 离子掺杂、无气泡、无云层和核心、尺寸约45 mm×80mm的粉红色Mn2 ∶BeAl2O4晶体。测定了不同部位晶体的激发光谱与荧光光谱。沿着晶体生长方向,晶体颜色逐步变深。在Mn2 ∶BeAl2O4荧光谱中观测到发光中心为543nm的荧光带,这归属于Mn2 的4T1(4G)→6A1(6S)能级跃迁所产生。在其激发光谱中观测到218nm的激发峰,这归属于电子从Mn2 基态到导带的电荷转移跃迁所致。从Mn2 离子的绿色发射情况可以推断Mn2 处于晶体中四面体场中,它取代晶体中Be2 离子的格位。从不同部位晶体的激发峰强度与颜色变化可以得到Mn2 在BeAl2O4晶体中的有效分凝系数小于1。     

Pr3+ luminescence center in Lu2Si2O7 host

Pr³⁺‐doped Lu₂Si₂O₇ (LPS:Pr) microcrystalline phosphor was prepared by the sol–gel method. We study the LPS:Pr luminescence properties under UV and X‐ray excitation within 80–500 K. The emission spectrum is dominated by fast 5d–4f band peaking at 261 nm having 16 ns decay time. By purely optical contactless methods we determine the energy barrier of 300 meV for thermal ionization of the Pr³⁺ 5d₁ relaxed excited state in LPS host. The barrier is high enough to keep the room temperature quantum efficiency of the Pr³⁺ luminescence center close to unity. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Electronic structure and optical properties of ABP2O7 double phosphates

Luminescence and luminescence excitation under VUV radiation of ${\mathrm{ABP}}_2{\mathrm{O}}_7$ ($\mathrm{A}=\mathrm{Na}$, K, Cs; $\mathrm{B}=\mathrm{Al}$, In) double phosphates are studied. Two emission bands peaking near 330 and 420 nm are common for investigated ${\mathrm{ABP}}_2{\mathrm{O}}_7$ crystals. The band structure and partial densities of electronic states of perfect ${\mathrm{KAlP}}_2{\mathrm{O}}_7$, ${\mathrm{LiInP}}_2{\mathrm{O}}_7$ and ${\mathrm{NaTiP}}_2{\mathrm{O}}_7$ crystals are calculated by the full-potential linear-augmented-plane-wave (FLAPW) method. It is found that the structures of the conduction bands of ${\mathrm{ABP}}_2{\mathrm{O}}_7$ crystals, which have different B cations, are appreciably different. Experimental results are compared with results of calculations of the electronic structure. Assumptions concerning the origin of luminescence in double phosphates are made.     

Zn_3V_2O_8和Zn_2V_2O_7的电子结构与光学性能的第一性原理研究

基于密度泛函理论(DFT)的第一性原理平面波超软赝势方法,在零压下建立了α-Zn_3V_2O_8和α-Zn_2V_2O_7晶体模型,分别对模型进行了电子结构和光学性质的计算.实验结果表明:α-Zn_3V_2O_8和α-Zn_2V_2O_7都属于间接带隙,α-Zn_3V_2O_8的禁带宽度为2. 715 eV,α-Zn_2V_2O_7的禁带宽度为2. 540 eV;同时,α-Zn_3V_2O_8和α-Zn_2V_2O_7都具有很强的紫外-近紫外光吸收能力;反射光谱、吸收光谱及能量损失谱的差异,共同导致Zn_3V_2O_8的光学性能要优异于Zn_2V_2O_7.     

Simultaneous three-photon-excited violet upconversion luminescence of Ce3+:Lu2Si2O7 single crystals by femtosecond laser irradiation

We found that Ce3+:Lu2Si2O7 single crystals could be excited at 800 nm by using a femtosecond Ti:sapphire laser. The emission spectra of Ce3+:Lu2Si2O7 crystals were the same for one-photon excitation at 267 nm as for excitation at 800 nm. The emission intensity of Ce3+:Lu2Si2O7 crystals was found to depend on the cube of the laser power at 800 nm, consistent with simultaneous absorption of three 800 nm photons. The measured value of the three-photon absorption cross section is sigma'3=2.44x10(-77) cm6 s2.     

BaMg2Si2O7:Eu3+和BaMg2Si2O7:Tb3+发光材料的合成及发光特性的研究

本文报道了首次合成的稀土离子激活的BaMg2Si2O7:Eu3+和BaMg2Si2O7:Tb3+光致发光材料,通过正交设计实验,确定了基质的最佳配比、烧结温度,探讨了影响材料发射强度的一些因素,测定了两种材料的发射光谱和激发光谱,对其发光性能也进行了分析和研究。     

Crystal structure,vibrational, and optical investigations of semiorganic nonlinear optical crystal: Bi3[CS(NH2)2]9Cl9· 2H2O

Tribismuthnonakisthioureanonachloride dihydrate (TBNTNC), a semiorganic nonlinear optical (NLO) material useful for frequency doubling in the IR region, has been grown by single diffusion gel technique. The grown crystal was confirmed by single crystal XRD and it crystallizes in triclinic system having P₁ space group. Vibrational analysis was carried out for the grown crystal. FTIR and FT‐Raman spectral studies were performed for analyzing and assigning the phonon vibrations and to identify the functional group contribution. The optical transmission study was carried out to examine the transmission ability of the crystal. The nonlinear optical property was confirmed by relative second harmonic generation measurement using Nd:YAG laser. Copyright © 2009 John Wiley & Sons, Ltd.     

Electronic structure and optical properties of Nb doped Al2O3 on Si by atomic layer deposition

Nb₂O₅ and Nb doped Al₂O₃ have proved to be good candidates as resistive switch materials or optical materials. In this letter, we focus on the complex electronic structure and optical properties of Nb doped Al₂O₃ to give chemical physical images of the films. With the help of SE, XPS and XPS valence band spectra, the detailed electronic structure with atomic bonding structure and optical properties are given. The band gap of a thin oxide film is determined to be 5.05 eV, and the evolution of VBO and CBO of the film on Si are also discussed.