Low-temperature synthesis of Zn2SiO4:Mn green photoluminescence phosphor

Zn₂SiO₄:Mn green phosphor having comparable photoluminescence (PL) efficiency with commercial phosphor has been synthesized at 1000 °C using solid state reactions involving ZnO, silicic acid and manganese acetate. The water of crystallization attached to SiO₂ in silicic acid whose dissociation at 1000 °C seem to promote the sintering efficiency of Zn₂SiO₄:Mn. Incremental ZnO addition and re-firing at 1000 °C promote the diffusion rate of ZnO and SiO₂. The formation of a single crystalline phase of willemite structure in the samples was confirmed by powder XRD measurements. The phosphor exhibit an intense excitation band centered around 275 nm and a relatively weak excitation centered around 380 nm while the broad band green emission peaks at 524 nm. Other parameters studied include PL spectra, grain morphology, ZnO/SiO₂ molar ratio, Mn concentration, co-dopant/flux and the effect of chemical forms of Mn dopant as well as silica on the PL efficiency.     

掺杂Mn2+的浓度对CdS纳米颗粒光致发光的影响

采用反胶束法,合成了硅土包裹的掺有不同浓度的Mn2 的CdS纳米颗粒.高分辨电镜表明这些颗粒的直径小于5 nm.仅仅改变Mn2 的掺杂浓度,研究了这些颗粒的光致发光谱和光致发光激发谱,结果表明:Mn2 浓度的大小对掺杂CdS纳米颗粒的发光产生了重要的影响.通过电子顺磁共振谱的测量和分析揭露了Mn2 浓度影响这些掺杂颗粒发光效率的原因.     

Effect of heat treatments on the luminescence properties of Zn2SiO4:Mn2+ phosphors prepared by glycothermal methods

Manganese-doped Zn₂SiO₄ phosphors with different crystal structures and morphologies were synthesized by glycothermal reactions of zinc acetate dihydrate and manganese(II) acetate tetrahydrate with tetraethyl orthosilicate in various glycols at 315 °C. The reactions in 1,3-propanediol and 1,4-butanediol yielded α-Zn₂SiO₄:Mn²⁺, whereas the reactions in ethylene glycol and 1,5-pentanediol yielded β-Zn₂SiO₄:Mn²⁺ and ZnO, respectively. The samples obtained in 1,4-butanediol and 1,3-propanediol emitted green light (522 nm), and the sample prepared in 1,4-butanediol showed a higher emission intensity. The photoluminescence intensity of the Zn_1.96Mn_0.04SiO₄ phosphor prepared by a glycothermal reaction in 1,4-butanediol and subsequently calcined at 1100 °C was twice as high as that of the sample synthesized by a conventional solid-state reaction. The high emission efficiency was obtained because the highly homogeneous distribution of Mn²⁺ in the α-Zn₂SiO₄ host synthesized by the glycothermal reaction was maintained during calcination treatment in air.     

Zn2SiO4:Mn2+荧光粉的燃烧法合成及其发光特性

用燃烧法成功合成了Zn2-xsiO4:xMn(0≤x≤0.10)粉末样品并表征了其发光特性.XRD测量结果表明,在600℃下燃烧数分钟、900℃以上进行热处理4 h后,所得样品为单相Zn2-xSiO4:xMn(0≤χ≤0.10,Willemite).监控525 nm发射,测得Zn2-xSiO4:xMn(0＜χ≤0.10)的最强激发峰为Mn2+的6A1→4T1跃迁(约254 nm).254 nm激发下,Zn2-xSiO4:xMn(0＜χ≤0.10)的最强发射峰为Mn2+的3d电子组态内自旋禁戒的4Ti→6AJ跃迁(约525 nm).结果表明,发光强度、最强峰位、最佳激活剂浓度等与初始原料、燃烧温度、燃烧剂的用量、粉末粒度等有关.     

溶胶-凝胶法制备绿色发光粉Zn_2SiO_4:Mn~(2+)及其发光性能

利用溶胶-凝胶法在加入H3BO3助熔剂的环境下制备了掺杂不同量Mn2+的Zn2SiO4绿色发光粉。用X射线衍射仪和荧光光谱仪对其结构和光致发光性能进行了测试分析。结果表明:900℃还原气氛下退火后,样品呈现明显的绿色,Mn2+最佳掺杂摩尔分数为2%,当掺杂量超过2%后光谱发生强烈的浓度猝灭效应。最后,对这种物质的发光机理进行了分析。     

Mg2+掺杂Zn2SiO4:Mn2+的溶胶-凝胶法合成及真空紫外发光特性研究

采用溶胶-凝胶法（sol-gel method）于不同气氛条件下成功合成了Zn_1.92-xMg_xSiO₄:0.08Mn²⁺（0≤x≤0.12）系列粉末样品.利用X射线衍射(XRD)、光致发光(PL)谱等分析手段对Zn_1.92-xMg_xSiO₄:0.08Mn²⁺系列     

Zn2 SiO4:Mn,Cd磷光体的长余辉特性

高温固相法合成Zn2SiO4：1．2％Mn,5％Cd长余辉磷光体,对样品进行了X射线衍射分析、光谱分析以及余辉衰减特性测量。分析结果表明,在1050℃下烧结3h的硅酸锌产物为单相。Zn2SiO4：1．2％Mn,5％CdK余辉磷光体在243nm或260nm激发下,发射光谱最大峰值位于521nm处,其色坐标x=0．2301,Y=0．69150在254nm紫外光激发5min后样品的余辉发光在暗室里可持续观察的时间约为1h,与Zn2SiO4：1．2％Mn磷光体比较,显示了更好的余辉特性。     

White-light generation through Ce3+/Mn2+-codoped and Eu2+-doped Ba1.2Ca0.8SiO4 T-phase phosphors

Hexagonal Ba_1.20Ca_0.8?2x?ySiO₄:xCe³⁺,xLi⁺,yMn²⁺ phosphors exhibit two emission bands peaking near 400 and 600 nm from the allowed f–d transition of Ce³⁺ ions and the forbidden ⁴T₁–⁶A₁ transition of Mn²⁺ ions, respectively. The strong interaction between Ce³⁺/Mn²⁺ ions is investigated in terms of energy transfer, crystal field effect, and microstructure by varying their concentrations. They show a higher quenching temperature of 250 °C than that of a commercially used (Ba,Sr)₂SiO₄:Eu²⁺ phosphor (150 °C). Finally, mixtures of these phosphors with green-emissive Ba_1.20Ca_0.70SiO₄:0.10Eu²⁺ are tested and yielded correlated color temperatures from 3500 to 7000 K, and color rendering indices up to 95%.     

纳米Zn_2SiO_4∶Mn包覆SiO_2颗粒的制备及表征

采用水热合成方法添加KOH在SiO2颗粒表面包覆Mn2+掺杂纳米Zn2SiO4,通过X射线衍射(XRD)仪、扫描电子显微镜(SEM)、能谱、光致发光(PL)光谱仪对产物的晶体结构、形貌及光学性能进行表征,并对Zn2SiO4晶体在水热反应过程中的反应机制进行了讨论。XRD测试结果表明:220℃水热条件下,添加少量KOH,反应不同时间后,可在石英砂表面生成一层Zn2SiO4;SEM照片显示所生成的Zn2SiO4为六棱柱形,并且不同反应条件下Zn2SiO4的包覆程度不同。反应产物经光致发光性能研究表明:Mn2+掺杂纳米Zn2SiO4包覆SiO2样品中显示两套光致发光谱,一套为250nm左右激发产生的522nm绿色发光带,另一套为340～410nm宽带激发的440nm蓝色发光带,前者为典型的Mn2+离子发光,后者440nm发光带则有可能来源于基体SiO2的氧空位缺陷。     

Cr4+掺杂Li1.14Zn1.43SiO4透明微晶玻璃近红外宽带光谱特性

采用高温熔融法和热处理制备了Cr⁴⁺掺杂Li_1.14Zn_1.43SiO₄微晶玻璃, 探讨了不同热处理温度下样品的物相、微观形貌及发光性能. 结果表明: 580℃热处理2h得到的微晶玻璃, Li_1.14Zn_1.43SiO₄微晶的粒径约为5nm, 在808nm的二极管激发下, 可观察到中心波长位于1226nm, 半高宽为230nm的近红外宽带发射峰, 荧光寿命约为200.73±1.71μs. 随着热处理温度的升高, Cr⁴⁺离子所处的晶体场环境发生了变化, 且可以观察到样品吸收光谱发生微弱的蓝移, 而荧光光谱发生少量的红移, 分析了晶体场环境变化对样品发光性能的影响. 关键词： 铬离子 微晶玻璃 超宽带发光 晶体场     

Photoluminescence of Pb2+-doped SrHfO3

Pb²⁺ excitation and emission spectra and decay kinetics in SrHfO₃ host are measured within 10–350 K temperature interval. Temperature dependence of decay times is fit by the phenomenological model describing the dynamics of the lowest excited state of Pb²⁺ ion. The best fit provided corresponding quantitative parameters of the model. Suitability of the Pb-doped SrHfO₃ for phosphor and scintillator application is discussed.     

Er3+掺杂SiO2复合的Al2O3粉末结构及光致发光特性

采用溶胶-凝胶(sol-gel)工艺制备0.1 mol% Er3+掺杂Al2O3体系和SiO2-Al2O3复合体系粉末. 实验结果表明:5 mol%的SiO2复合加入Al2O3抑制γ→θ和θ→α相转变. 掺0.1 mol%Er3+:Al2O3体系粉末,900℃烧结,在1.47-1.63 μm波段内光致发光(PL)谱为中心波长1.53 μm、半高宽56 nm的单一宽峰,1000-1200℃烧结,劈裂为多峰PL谱. 掺0.1 mol%Er3+:SiO2-Al2O3复合体系粉末,在高达1200℃烧结,仍保持中心波长1.53 μm的单一宽峰PL谱,由于-OH更完全的脱除,PL强度较900℃烧结Al2O3体系,SiO2-Al2O3复合体系均提高1个数量级.     

Zn2SiO4(ZnB2O4):Mn2+,Sm3+发光材料的制备与荧光性能

使用高温固相法首次合成了Zn2SiO4(ZnB2O4):Mn2+,Sm3+发光材料,探讨了烧结温度、Sm2+含量对样品荧光性能的影响.利用X射线衍射(XRD)、荧光光谱等分析手段对Zn2SiO4(ZnB2O4):Mn2+,Sm3+粉末的结构、发光性能进行了表征.确定了该荧光材料的最佳合成条件,离子掺杂浓度等.实验结果表...     

Effects of alkali metal ions on upconversion photoluminescence intensity of Er3+-doped Y2O3 nanocrystals

We investigate upconversion emissions in alkali metal ions (Li⁺, Na⁺, and K⁺) and Er³⁺-codoped Y₂O₃ nanocrystals. By introducing Li⁺, upconversion intensity is significantly enhanced, while Na⁺ and K⁺ hardly have this influence. FT-IR data give evidence that the main mechanisms of the enhanced upconversion emission cannot be attributed to the decreased surface defects. EXAFS data and variations of enhanced upconversion intensities in different samples indicate that Li⁺ can occupy the interstitial sites in lattice and thus arouse large site asymmetry. In addition, locations in the samples and effects on the upconversion emission of Na⁺ and K⁺ are discussed.     

Origin of the Concentration Quenching of Luminescence in Zn2SiO4:Mn Phosphors

Physics of the Solid State - The analysis of the unified series of single-phase Zn2 – 2xMn2xSiO4 samples (x ≤ 0.2) has provided the possibility to determine the...