自蔓延燃烧法制备Ba3MgSi2O8∶Eu2+,Mn2+荧光粉

本文以乙二醇为溶剂,无水乙醇为助燃剂,首次采用自蔓延燃烧法制备了白光LED用Ba3Mgsi2O8∶Eu2+,Mn2+荧光粉,利用XRD、粒度分析仪和荧光分光光度计对样品进行了测试,荧光分析结果表明:在375nm波长光源激发下,1100℃制备的样品可同时发射绿、蓝两色光.     

草酸沉淀法制备纳米晶Y2O3:Eu3+及粉体评价

报道了草酸作为沉淀剂并添加表面活性剂合成了纳米晶Y2O3：Eu^3 的方法,其一次粒径为20-30nm,团聚尺寸D50=0.53μm。粉体细且分布均匀。与微米晶比较,该纳米晶的发射光谱发生明显蓝移,色座标合荧光粉要求。     

Sr2MgSiO5:(Eu2+,Mn2+)单一基质白光荧光粉的发光性质

研究了Eu2 ,Mn2 共激活的单一基质Sr2MgSiO5白光发光材料的发光性质.Eu2 中心形成峰值分别为459,555nm的特征宽带,而Eu2 中心向Mn2 中心的能量传递导致了峰值为678 nm的发射,3个谱带叠加从而在单一基质中得到了白光.其激发光谱分布在250～450nm的波长范围,峰值位于390nm,可以被InGaN 管芯产生的380～410nm辐射有效激发.Sr2MgSiO5:(Eu2 ,Mn2 )是一种性能良好的单一基质白光发光二极管用荧光粉.     

Sr8Si4O12Cl8:Eu3+,M3+(M3+=Bi3+,Gd3+)中Eu3+的敏化发光

以Na2CO3为电荷补偿剂,采用高温固相法合成了碱土氯硅酸盐Sr8Si4O12Cl8:(Eu3 M3 )(M=Bi3 ,Gd3 )荧光材料.X射线衍射分析结果表明:合成的Sr8Si4O12Cl8:(Eu3 ,M3 )为纯四方相.Eu3 的发射主峰位于614 nm,为5D0→7F2的电偶极跃迁,表明Eu3 处于非中心对称格位,即取代Sr2 的位置.通过对其激发光谱和发射光谱研究,发现敏化剂Bi3 ,Gd3 的掺入对Eu3 的发射具有较强的敏化作用,当Bi3 和Gd3 的掺杂量(摩尔分数)分别为5.0%时,Eu3 的相对发光强度分别提高了29.4%和23.6%.     

液相沉淀法制备纳米Mn2O3

以MnCl2.2H2O和(NH4)2CO3为原料,采用液相沉淀法制备了前驱物,并对前驱物在不同温度下进行了热处理。经处理后的产物分别作了XRD和TEM表征,结果表明,制备纳米粉体Mn2O3的适合温度范围为600℃~800℃,800℃下热处理的产物粒度分布均匀,平均粒径为90nm左右。     

正交法优化纳米SrAl2O4:Eu2+,Dy3+制备工艺

采用溶胶-凝胶法合成了SrAl2O4:Eu2+,Dy3+纳米长余辉发光材料,利用正交设计法优化了制备工艺.在传统溶胶-凝胶法基础上,添加了硼酸,在950℃生成单一晶相,该法能使SrAl2O4生成温度降低150℃,生成的磷光体发光强度高、余辉时间长,平均晶粒尺寸为25～90nm.     

SrAl2O4:Eu2+,Dy3+,Pr3+纳米长余辉发光材料的制备与表征

以硝酸盐和尿素为基质,采用燃烧法在650℃合成了SrAl2O4:Eu2+,Dy3+,Pr3+长余辉发光粉体.研究了样品的晶体结构、晶粒大小及发光性能.结果表明:Eu2+,Dy3+,Pr3+共掺杂的磷光体没有改变铝酸锶的晶体结构,平均晶粒尺寸为41.5nm;激发和发射光谱分别为360nm和515nm的宽带谱,与SrAl2...     

Gd2O3:Eu荧光粉体的制备及其发光特性

分别采用溶胶-凝胶/燃烧合成结合法和共沉淀法合成了Gd2O3:Eu粉体,借助X射线衍射、扫描电镜、透射电镜、分光光度计等分析手段,对比研究了两种工艺制备Gd2O3:Eu荧光粉体的物相组成、形貌及荧光特性.结果表明:共沉淀法合成的Gd2O3:Eu为立方相;溶胶-凝胶/燃烧合成法制备的Gd2O3:Eu为单斜相.溶胶-凝胶/燃烧合成法制备的Gd2O2:Eu粉体蓬松、多孔,但存在一定程度的团聚.共沉淀法制备的立方相Gd2O3:Eu粉体在610 nm处呈现Eu2 的特征荧光;溶胶-凝胶/燃烧合成法制备的单斜相Gd2O3:Eu的发射波长产生红移,其中最强的2个发射峰起源于Eu3 的5D0→7F2跃迁,分别位于612 nm和621 nm.两种工艺制备Gd2O3:Eu粉体荧光特性的差异是由Eu3 在这两种粉体中所处晶格结构的对称性差异引起的.     

溶胶-凝胶法制备SrAl2O4:Eu2+,Dy3+纳米发光材料

采用溶胶-凝胶法在低温、还原气氛下制备了SrAl2O4：Eu^2 ，Dy^3 纳米长余辉光致发光材料。XRD分析表明，当焙烧温度为800～1300℃时，所合成的样品为SrAlO4单斜晶系晶体结构，晶格常数为：a=0．84424mn，b=0．8822mn，c=0．51607mn。1100℃以上观察到样品长余辉发光。激发光谱与发射光谱分析表明：发射光谱是峰值位于523nm的宽带谱，激发光谱是峰值在240，330，378，425nm的连续宽带谱。样品在自然光照射后持续发出明亮的绿光。样品的合成温度从1100℃增加到1300℃，样品的颗粒尺寸不断增大。TEM和电子衍射分析表明，1100℃烧结4h的SrAl2O4：Eu^2 ，Dy^3 纳米粉末为结晶相，粒径为30～40nm。     

Effect of Sr and Ca substitution of Ba on the photoluminescence properties of the Eu2+ activated Ba2MgSi2O7 phosphor

The effects of Sr and Ca substitution of Ba on the Ba_1.98-xSr_x(Ca_x)MgSi₂O₇:Eu²⁺ photoluminescence properties have been investigated. The physical mechanisms for the photoluminescence variations are discussed. With Rietveld refinement method, the crystal structure of Ba_1.98MgSi₂O₇:0.02Eu²⁺ and the lattice parameters of Sr and Ca substituted phosphors were refined. The emission band shift, the photoluminescence intensity variation, the phosphor chromaticity evolution, the Eu²⁺ lifetime distribution and the thermal stability elevation were investigated. With Sr and Ca substitution, the cell is shrinks. The cell shrinkage is resulting in the increase of the Eu²⁺ 5d electron crystal field splitting intensity, which is the reason for the emission band shift towards the long wavelength band. The photoluminescence intensity is increased firstly and then decreased. The intensity variation is the competitive result between the increase of the crystal structure rigidity and the rise of the lattice defect. The correlated color temperature can be cut down and the color purity can be adjusted. The photoluminescence life time of Eu²⁺ is raised firstly and then decreased. For Sr and Ca substitution, the thermal stability can be elevated. With the forbidden band gap calculation, the reason for the thermal stability elevation was investigated that for the substituted phosphors the forbidden band gap is enlarged and then limits the Eu²⁺ 5d self-ionization from the splitting levels to the conduction band. This work reveals that the Sr and Ca substitution of Ba can elevate the Ba_1.98-xSr_x(Ca_x)MgSi₂O₇:Eu²⁺ photoluminescence properties and improve the applications for the White Light Emitting Diode.     

Ca3MgSi2O8:RE(RE=Eu2+,Ce3+,Tb3+)的发光性能

采用高温固相法在还原气氛下合成了Ca3MgSi2O8:RE(RE=Eu2 ,Ce3 ,Tb3 )系列样品.用荧光光谱仪研究了样品掺杂Eu2 ,Ce3 ,Tb3 后的光谱性质.样品Ca3MgSi2O8:Ce3 在紫外光激发下呈蓝紫色发射;样品Ca3MgSi2O8:Eu2 在紫外光激发下则呈绿色发射.分别讨论了Ce3 ,Eu2 和Ce3 ,Tb3 共激活焦硅酸钙盐在紫外光激发下的光谱特性和其中存在的能量传递机理,发现Ce3 分别对Eu2 和Tb3 有敏化作用.     

Incommensurate phases in the system Ba2TiSi2O8-Ba2TiGe2O8

Incommensurate phases and phase transitions in fresnoite-type crystals: Ba₂TiSi₂O₈, Ba₂TiGe₂O₈, and compositions in the system Ba₂TiSi₂O₈-Ba₂TiGe₂O₈, are discussed.     

极性微晶玻璃的结构与热释电性能研究

采用高温熔融方法制备了Ba2-xSrxTiSi2O8 (简称BSTS)非铁电极性微晶玻璃.用 XRD和SEM分析了其取向生长的结构特性.BSTS微晶玻璃使用温度高,不易老化,抗磁电干扰,同时具有较大的热释电电压及探测率优值因子,分别为0.27m2·C-1和10-5 Pa-1/2,其非制冷热释电探测器探测率D·(500,80,1)为1.5×107cm·Hz·W-1,适合于热释电探测器方面应用.     

离子液体辅助液相沉淀法制备纳米La_2O_3

文章以碳酸镧为原料,以氢氧化钠为沉淀剂利用液相沉淀法在离子液体[Bz MIm]BF_4中制备出了纳米La_2O_3粉体。用透射电镜观察粒子的形貌和大小,用马尔文激光粒度分析仪测定粒径分布情况,用比表面仪测定粒子的比表面积。实验结果表明,纳米氧化镧的平均粒径随反应温度、反应物浓度、煅烧温度和时间的增加都呈现出先增大后减小的趋势。本实验过程中,当反应温度90℃,煅烧温度720℃,m([BzMIm]BF_4)/m(La(OH)_3)=2∶3,煅烧1.5 h时,制得的氧化镧粒径分布较均匀,团聚较少,大部分处于14~50 nm,呈长条状,其重量比表面积为53.793 m~2/g。     

Preparation,structural and microstructural properties of Ba0.64Ca0.32Al2Si2O8 ceramics phase

Monoclinic celsian has been prepared from Ba-LTA zeolite precursor. The Ca²⁺-exchanged hexacelsian (HC_Ca) synthesized from Ba-LTA zeolite precursors was used for preparation of monoclinic celsian (MC_Ca). The partially ion exchange diphyllosilicate has a composition of Ba_0.64Ca_0.32Al₂Si₂O₈ (HC_Ca). It was found that prepared HC_Ca phase is stable between room temperature and 1300 °C. During prolonged heating this phase is polymorphic transformed to Ba, Ca-celsian feldspar. Synthesis of Ba, Ca-celsian and thermal behavior during transformation processes was observed by XRD method. The crystal structure and microstructural parameters were refined using Rietveld method. The crystal morphology of thermal treated samples was observed by SEM/EDAX analysis.     

固体超强酸催化剂S2O2-8/Fe2O3-Al2O3的制备及其酯化性能

以硝酸铁为铁源、硝酸铝为铝源,通过共沉淀法制备固体超强酸催化剂S₂O^2-₈/Fe₂O₃-Al₂O₃。通过催化剂样品的FT-IR谱图、不同焙烧温度催化剂样品的XRD谱图、不同陈化温度的N2吸附-脱附曲线以及催化剂样品的SEM照片,研究了其晶体的形成过程。催化剂样品红外谱图表明,催化剂中的S=O有较强的共价双键特征,诱导催化剂形成超强酸性;在XRD谱图中既无Al₂O₃的晶相峰,也无Fe₂(SO₄)₃晶相峰,说明Al₂O₃与Fe₂O₃ 在催化剂样品的表面形成了Al₂O₃-Fe₂O₃ 共价键的复杂结构。采用BET方程和BJH模型计算催化剂样品的比表面积和孔径分布,经冰水陈化的催化剂样品平均孔径为9.1 nm,最可几孔径为7.5 nm,比表面积为78.9 m²·g^-1,孔容0.149 cm³·g^-1。研究了催化剂的铁与铝物质的量比、(NH₄)₂S₂O₈浸渍浓度和不同焙烧温度对硬脂酸正丁酯酯化率的影响。在反应温度85 ℃、催化剂用量0.2 g (为反应物总质量的2%)和回流反应150 min的条件下,酯化率可达84.5%。     

The catalytic oxidation of CO on superconductor Ba2YCu3O7–8

The measurements of MS-TPD, TPRS, the electrical conductivity and kinetics on Ba₂YCu₃O_7-8 show that the catalytic activity of CO oxidation is closely related to properties such as the amounts and sites of oxygen, and electrical conductivity. Based on the experimental results a reaction mechanism has been suggested.     

非均匀沉淀法制备黑色氧化锆陶瓷

以Y-TZP（氧化钇稳定四方多晶氧化锆）为原料、硝酸锰和硝酸铝为着色剂、PEG2000（聚乙二醇2000）为分散剂,采用非均匀沉淀法制备着色剂/氧化锆复合粉体,经成型、烧结后得到黑色氧化锆陶瓷。采用X射线衍射,扫描电子显微镜、X射线荧光分析和透射电子显微镜等对复合粉体和陶瓷的结构和性能进行表征,结果表明：着色剂/氧化锆...