水热法合成ZnS:Au,Cu超细X射线发光粉

报道了水热法合成的高强度ZnS:Au,Cu超细X射线发光粉及其光致发光(PL)和X射线激发发光(XEL)的光谱特性.200℃水热处理12 h直接合成样品的纳米晶粒约15 nm,尺寸分布窄,分散性好,具有纯立方相的类球形结构.氩气保护下1000℃焙烧1 h后的样品存在一定的团聚,但团聚后尺寸为1～2μm,为超细X射线发光粉,此时样品为纯六角相的类球形为主的结构.所有样品的PL和XEL光谱均为宽带谱,水热法直接合成样品的XEL强度最强时,样品的Cu/Zn,Au/Cu比值分别为3×10-5和2.在此比值条件下,1000℃焙烧1h样品的XEL发光最强,此时其2个峰值分别位于445和513 nm,且与未焙烧前相比强度增强了10倍左右.另外通过比较PL光谱与XEL光谱特性,讨论了PL和XEL光谱的发光机理和其不同的激发机制.     

水热法合成ZnS∶Au,Cu超细X射线发光粉

报道了水热法合成的高强度ZnS∶Au,Cu超细X射线发光粉及其光致发光(PL)和X射线激发发光(XEL)的光谱特性。200℃水热处理12h直接合成样品的纳米晶粒约15nm,尺寸分布窄,分散性好,具有纯立方相的类球形结构。氩气保护下1000℃焙烧1h后的样品存在一定的团聚,但团聚后尺寸为1～2μm,为超细X射线发光粉,此时样品为纯六角相的类球形为主的结构。所有样品的PL和XEL光谱均为宽带谱,水热法直接合成样品的XEL强度最强时,样品的Cu/Zn,Au/Cu比值分别为3×10-5和2。在此比值条件下,1000℃焙烧1h样品的XEL发光最强,此时其2个峰值分别位于445和513nm,且与未焙烧前相比强度增强了10倍左右。另外通过比较PL光谱与XEL光谱特性,讨论了PL和XEL光谱的发光机理和其不同的激发机制。     

水热合成ZnS:Cu,Al纳米晶体及其全色发射光谱特性

报道了水热法(200℃)直接合成的ZnS:Cu,Al纳米晶及其发光特性.ZnS:Cu,Al纳米晶粒径约15 nm,尺寸分布窄,分散性好,具有纯立方相的类球形结构.借助X射线能谱法(EDX)和原子吸收光谱仪,研究了样品中S,Zn和Cu的含量并详细研究了光致发光(PL)光谱的特性.结果证明存在大量Zn空缺,Cu离子经过水热处理后已掺入到ZnS基体中.PL光谱特性为:样品的激发谱为宽带谱,337 nm激发时样品发出很强的绿光,370～420 nm之间任意波长激发时,发射谱均为宽带谱,且它们基本重合.表明此材料作为近紫外(370～410 nm)发光二极管((n)-UV(370～410 nm)LED)用荧光粉及全色荧光粉具有很大的应用潜力.样品在375 nm激发下全色宽带发射谱是460,510和576 nm带光谱的高斯叠加.当Cu/Zn,Cu/Al和S/Zn分别为3×10-4,2和3.0时,于室内照明条件下肉眼可观察到白色发光.     

退火对ZnS/PS复合体系光致发光特性的影响

用脉冲激光沉积(PLD)技术以多孔硅(PS)为衬底生长了ZnS薄膜,分别测量了ZnS、PS以及ZnS/PS复合体系在室温下的光致发光(PL)光谱。结果发现,ZnS/PS复合体系的PL光谱中PS的发光峰位相对于新制备的PS有所蓝移。把该ZnS/PS样品分成三块,在真空400℃分别退火10,20,30 min,研究不同退火时间对ZnS/PS复合体系光致发光特性的影响。发现退火后样品的PL光谱中都出现了一个新的绿色发光带,归结为ZnS的缺陷中心发光。随着退火时间的延长,PS的发光强度逐渐降低且峰位红移。把ZnS的蓝、绿光与PS的红光相叠加,整个ZnS/PS复合体系在可见光区450~700 nm形成一个较宽的光致发光谱带,呈现较强的白光发射。     

SnO2:Eu3+纳米晶的水热法制备及发光性能

采用水热法制备了Eu3+掺杂SnO2纳米发光粉,样品在不同温度下热处理得到不同粒径尺寸的纳米颗粒.利用X射线衍射(XRD)与光致发光(PL)谱对样品进行表征.XRD分析表明:SnO2:Eu3+样品均为纯相金红石结构.PL测量表明:水热法直接制备的样品的激发谱由Eu3+的f-f本征激发峰组成,而经过热处理后样品的激发谱由O2--Eu3+电荷迁移带和Eu3+的f-f本征激发组成;样品的发光强度与颗粒大小有密切关系.     

~(147)Pm激发的ZnS∶Cu,Cl发光粉的研究

以高纯ZnS粉末为基质,采用高温转相、扩散,以及表面涂敷工艺,制得了147Pm激发的ZnS∶Cu,Cl发光粉。分析了ZnS∶Cu,Cl的晶体结构,测量了ZnS∶Cu,Cl的激发光谱、发射光谱、发光亮度。其晶体结构主要是六方纤锌矿型结构,激发光谱峰值波长为341nm,发射光谱峰值波长为513nm,初始发光亮度达到312mcd/m2。由激发光谱的峰值波长341nm推算得到六方ZnS晶体的禁带宽度为3.64eV。分析了147Pm激发的ZnS∶Cu,Cl发光粉的发光寿命,其发光寿命达到5年以上。还探讨了该放射性发光粉的发光机理。147Pm激发的ZnS∶Cu,Cl的稳定发光,实际上是激发过程与复合过程的准平衡。ZnS∶Cu,Cl的绿色发光来源于深施主-深受主对的复合发射。实验结果的分析表明,ZnS∶Cu,Cl中深施主-深受主之间的能级间隔约为2.42eV。     

掺Fe铝酸锂晶体的光谱性能研究

采用提拉法生长了质量较高的掺Fe铝酸锂(LiAlO2:Fe)晶体,并用吸收光谱、光致激发与发射光谱以及X射线激发发射(XEL)光谱测试等方法对晶体的光谱性质及结构进行了研究。结果表明,晶体对可见光与近红外光具有较高的透过,而在深紫外波段存在与Fe离子相关的吸收。以266nm光激发得到710nm的Fe3+离子的特征发射峰,分析表明晶体中Fe3+离子代替Li+离子而处于8面体格位。比较不同晶体样品的XEL光谱发现,空气退火后的γ-LiAlO2晶体出现了318nm处较强的缺陷发光,而同样条件退火后的LiAlO2:Fe晶体与未退火的γ-LiAlO2晶体均未观察到相应的发光。分析得出此发光应与晶体退火后形成的F+心有关,而Fe掺杂可抑制晶体中Li2O的挥发,提高晶体的热稳定性。     

147Pm激发的ZnS：Cu,Cl发光粉的研究

以高纯ZnS粉末为基质,采用高温转相、扩散,以及表面涂敷工艺,制得了¹⁴⁷Pm激发的ZnS:Cu,Cl发光粉。分析了ZnS:Cu,Cl的晶体结构,测量了ZnS:Cu,Cl的激发光谱、发射光谱、发光亮度。其晶体结构主要是六方纤锌矿型结构,激发光谱峰值波长为341nm,发射光谱峰值波长为513nm,初始发光亮度达到312mcd/m₂。由激发光谱的峰值波长341nm推算得到六方ZnS晶体的禁带宽度为3.64eV。分析了¹⁴⁷Pm激发的ZnS:Cu,Cl发光粉的发光寿命,其发光寿命达到5年以上。还探讨了该放射性发光粉的发光机理。¹⁴⁷Pm激发的ZnS:Cu,Cl的稳定发光,实际上是激发过程与复合过程的准平衡。ZnS:Cu,Cl的绿色发光来源于深施主-深受主对的复合发射。实验结果的分析表明,ZnS:Cu,Cl中深施主-深受主之间的能级间隔约为2.42eV。     

燃烧法合成Ln_2O_2S∶RE~(3+)(Ln=Gd,La;RE=Eu,Tb)X射线荧光粉及发光性能

采用燃烧合成法,以稀土硝酸盐和二硫代乙二酰胺为反应物,通过控制两者的摩尔比例,在点燃温度为300 ~350℃时,制备了掺杂不同浓度稀土激活剂离子的硫氧化物X射线荧光粉。分别以X射线衍射(XRD)、扫描电子显微镜(SEM)、光致发光(PL)光谱及X射线激发的发光(XEL)光谱对样品进行了表征。XRD分析表明,当热处理温度低于500℃时,可得到单一相的硫氧化物X射线荧光粉,这就避免了高温烧结的缺点;而当烧结温度较高时,开始有硫酸氧化物出现。从SEM图像中可以看到荧光粉粉末具有疏松和多孔连续的三维的网络块状结构,但其初级粒子尺寸较小,均小于50nm,这在一定程度上,可以提高成像系统的空间分辨率。PL光谱分析表明,所制备的荧光粉样品分别呈现出Eu3+,Tb3+离子的特征发射。XEL光谱结果表明,尽管它与光致发光的激发原理不一样,但同样呈现出Eu3+,Tb3+离子的特征发射;这些样品本身对X射线的吸收系数及掺杂浓度不一样,因此它们的光发射效率也有所差别。     

燃烧法合成Ln2O2 S:RE3+(Ln=Gd,La;RE=Eu,Tb) X射线荧光粉及发光性能

采用燃烧合成法,以稀土硝酸盐和二硫代乙二酰胺为反应物,通过控制两者的摩尔比例,在点燃温度为300—350℃时,制备了掺杂不同浓度稀土激活剂离子的硫氧化物X射线荧光粉。分别以X射线衍射(XRD)、扫描电子显微镜(SEM)、光致发光(PL)光谱及X射线激发的发光(XEL)光谱对样品进行了表征。XRD分析表明,当热处理温度低于500℃时,可得到单一相的硫氧化物X射线荧光粉,这就避免了高温烧结的缺点;而当烧结温度较高时,开始有硫酸氧化物出现。从SEM图像中可以看到荧光粉粉末具有疏松和多孔连续的三维的网络块状结构,但其初级粒子尺寸较小,均小于50nm,这在一定程度上,可以提高成像系统的空间分辨率。PL光谱分析表明,所制备的荧光粉样品分别呈现出Eu^3 ,Tb^3 离子的特征发射。XEL光谱结果表明,尽管它与光致发光的激发原理不一样,但同样呈现出Eu^3 ,TB^3 离子的特征发射;这些样品本身对X射线的吸收系数及掺杂浓度不一样,因此它们的光发射效率也有所差别。     

Hydrothermal synthesis and optical properties of full-color-emission ZnS:Cu, Al nanocrystals

ZnS:Cu, Al nanocrystals were synthesized by a hydrothermal method at 200 degrees C and their optical properties were studied. The analysis of XRD and TEM show that the spherical-like nanocrystals had a grain size of approximately 15 nm and were well dispersed, with a zinc blende structure. The energy dispersive X-ray spectroscopy (EDX) and atomic absorption spectrometry were applied to the analysis of S, Zn and Cu content in the sample. The results proved that a large number of zinc vacancies exist and Cu is incorporated into the sample lattice. The photoluminescence (PL) spectra were investigated. The PL mechanism is discussed. The excitation spectrum is broad. Under 337 nm excitation the sample emits bright green light. Under 370-410 nm excitation the sample emits white light. The broad emission spectra are almost coincident with any excitation wavelength of between 370 and 410 nm making them attractive as conversion phosphors for LED applications and full-color fluorescence display devices. The emitted white light under 375 nm excitation was found to be the result of blue, green, and orange emission bands. For Cu/Zn, Cu/Al and S/Zn molar ratios of 3 x 10(-4), 2 and 3, respectively, the near blue white light can be observed with the naked eye in daylight.     

氮气氛中高温退火对NaYF4:Yb3+,Er3+纳米粒子上转换发光的影响

以柠檬酸三钠为螯合剂,采用共沉淀和水热相结合的方法成功制备出尺寸为40 nm的NaYF4:Yb3+Er3+纳米粒子.将得到的部分样晶在300℃氮气保护下退火2h.退火前后的样品晶体结构都属于立方相,尺寸保持在40 nm左右.在980 nm光激发下,退火后样品的上转换发光整体强度和绿光相对发射强度明显增强.分析认为高温退...     

Luminescence mechanism of ZnO thin film investigated by XPS measurement

The effects of annealing environment on the luminescence characteristics of ZnO thin films that were deposited on SiO₂/Si substrates by reactive RF magnetron sputtering were investigated by X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL). An analysis of the O 1s peak of ZnO film revealed that the concentration of oxygen vacancies increased with the annealing temperature from 600 °C to 900 °C under an ambient atmosphere. The PL results demonstrated that the intensity of green light emission at 523 nm also increased with temperature. Under various annealing atmospheres, the analyses of PL indicated that only one emission peak (523 nm) was obtained, indicating that only one class of defect was responsible for the green luminescence. The green light emission was strongest and the concentration of oxygen vacancies was highest when the ZnO film was annealed in ambient atmosphere at 900 °C. The results in this investigation show that the luminescence mechanism of the emission of green light from a ZnO thin film is associated primarily with oxygen vacancies. PACS 81.15.Cd; 81.40.Ef; 78.55.-m; 78.55.Et     

LED用La2(WO4)3∶Eu3+红色荧光粉合成及光谱性能

 采用水热法并进行热处理成功合成了Eu3+掺杂La2(WO4)3红色荧光粉.通过粉末X射线衍射、扫描电子显微镜,以及能谱来表征荧光粉的晶体结构、颗粒大小、形貌及成分|用激发光谱和发射光谱以及荧光衰减曲线来表征荧光粉的荧光性能.X射线衍射分析确认了水热的前驱体和后期热处理的样品主要相分别为三斜晶系的La2W2O9和单斜晶系的La2(WO4)3.激发光谱表明La2(WO4)3∶Eu3+荧光粉样品在395 nm处有一个最强的吸收峰,与紫外InGaN LED芯片发射波长相匹配|而且La2－xEux(WO4)3荧光粉在395 nm激发下有强红光发射.因此,La2－xEux(WO4)3荧光粉有望成为新一代白光LED用的红色荧光粉.     

不同退火条件对纳米多孔氧化铝薄膜光致发光的影响

以草酸为电解液,采用二次阳极氧化法制备出了纳米多孔氧化铝薄膜,经不同退火温度和退火气氛处理氧化铝薄膜后,通过分析其光致发光光谱得出：相同的退火气氛中, 退火温度T≤600 ℃ 时,T=500 ℃具有最大的光致发光强度;退火温度T≥700 ℃时,随着退火温度的升高,样品的发光强度增大。在不同的退火气氛中,多孔氧化铝薄膜随着退火温度的升高,发光峰位改变不同,即在空气中退火处理后,随着退火温度的升高,发光峰位蓝移,而在真空中退火处理后,发光峰位并不随退火温度的升高而变化;通过对1 100 ℃高温退火处理后的氧化铝薄膜的光致发光曲线的高斯拟合,可以看出,经退火处理后的多孔氧化铝,主要存在三个发光中心,发光曲线在350～600 nm范围内对应三个发射峰, 发射波长分别为387,410,439 nm。相同的退火温度下,空气中退火得到的氧化铝薄膜的光致发光强度大于真空中退火处理后的氧化铝薄膜。基于实验结果,结合X射线色散能谱(EDS)、红外反射光谱等表征手段,探讨了多孔氧化铝薄膜的发光机制,并对经过不同退火条件得到的多孔氧化铝薄膜的光致发光特性的改变做出了合理的解释。     

Intense red upconversion fluorescence emission in NIR-excited erbium-ytterbium doped laponite-derived phosphor

In this report the optical properties and energy-transfer frequency upconversion luminescence of Er³⁺/Yb³⁺-codoped laponite-derived powders under 975 nm infrared excitation is investigated. The 75%(laponite):25%(PbF₂) samples doped with erbium and ytterbium ions, generated high intensity red emission around 660 nm and lower intensity green emission around 525, and 545 nm. The observed emission signals were examined as a function of the excitation power and annealing temperature. The results indicate that energy-transfer, and excited-state absorption are the major upconversion excitation mechanism for the erbium excited-state red emitting level. The precursor glass samples were also heat treated at annealing temperatures of 300 °C, 400 °C, 500 °C, and 600 °C, for a 2 h period. The dependence of the visible upconversion luminescence emission upon the annealing temperature indicated the existence of an optimum temperature which leads to the generation of the most intense and spectrally pure red emission signal.     

纳米晶ZnO可见发射机制的研究

利用化学沉淀法制备了纳米ZnO粉体,室温下测量了样品的光致发光谱(PL)、X射线衍射谱(XRD),给出了样品的透射电子显微照片(TEM).X射线衍射(XRD)的结果表明:纳米晶ZnO具有六角纤锌矿晶体结构,颗粒呈球形或椭球形.观察到二个荧光发射带,中心波长分别位于398 nm的紫带和510 nm的绿光带.发现随退火温度升高,粒径增大,紫带的峰值减弱、绿带的峰值增强.证实了纳米晶ZnO绿光可见发射带来自氧空位形成的施主和锌空位形成的受主之间的复合.     

Effects of high-dose Ge ion implantation and post-implantation annealing on ZnO thin films

This paper reports that ion implantation to a dose of 1×10¹⁷ ions/cm² was performed on c-axis-orientated ZnO thin films deposited on (0001) sapphire substrates by the sol-gel technique. After ion implantation, the as-implanted ZnO films were annealed in argon ambient at different temperatures from 600-900℃. The effects of ion implantation and post-implantation annealing on the structural and optical properties of the ZnO films were investigated by x-ray diffraction (XRD), photoluminescence (PL). It was found that the intensities of (002) peak and near band edge (NBE) exitonic ultraviolet emission increased with increasing annealing temperature from 600-900℃. The defect related deep level emission (DLE) firstly increased with increasing annealing temperature from 600- 750℃, and then decreased quickly with increasing annealing temperature. The recovery of the intensities of NBE and DLE occurs at \sim 850℃ and \sim 750℃ respectively. The relative PL intensity ratio of NBE to DLE showed that the quality of ZnO films increased continuously with increasing annealing temperature from 600 - 900℃.     

稀土Tb3+掺杂纳米ZnO的发光性质

ZnO是一种优良的直接宽带隙半导体发光材料(Eg=3.4 eV),具有优异的晶格、光学和电学性质,稀土离子掺杂浓度和热处理温度对ZnO∶Re3 纳米晶发光强度、峰位变化等光学性质具有重要影响.利用溶胶-凝胶法(Sol-Gel),在不同退火温度下,制备了不同浓度的ZnO∶Tb3 纳米晶.室温下,测量了样品的X射线衍射谱(XRD)、光致发光谱(PL)和激发谱(PLE).观察到纳米ZnO基质在520 nm附近宽的绿光可见发射和稀土Tb3 在485,544,584和620 nm附近的特征发射.通过ZnO基质可见发射强度和稀土Tb3 特征发射强度随Tb3 掺杂浓度、退火温度的变化关系,获得了5D4→7F5跃迁的绿色主发射峰最强的样品制备工艺参数,其退火温度为600℃、掺杂浓度为4 at%;给出了稀土Tb3 的激发态5D4→7F6(485 nm),5D4→7F5(544 nm)和5D4→7F4(584 nm)的发射机制;证实了稀土Tb3 与纳米ZnO基质之间存在双向能量传递.