Eu2+掺杂MgY2Al3Si2O11N青光荧光粉的制备和发光性能

采用高温固相法合成了一系列Eu²⁺掺杂的Mg Y₂Al₃Si₂O₁₁N(MYASON)青光荧光粉。详细探讨了不同制备方法对荧光粉的物相结构和发光强度的影响,利用X射线衍射精修和X射线光电子能谱实验证明Si⁴⁺-N^3-离子对成功掺入石榴石晶格中。通过荧光光谱、寿命衰减曲线和变温光谱研究了发光性能,研究结果表明,用365 nm紫外光激发MYASON∶Eu²⁺荧光粉时,在青光区域呈现不对称宽带发射,峰值为490 nm,可以为紫外芯片激发的白光发光二极管有效提供青光成分。     

Sr2Si5N8∶Eu2+荧光粉的制备与发光性能

以α-Si₃N₄,SrCO₃,Eu₂O₃为原料,采用碳热还原氮化法制备了Sr₂Si₅N₈∶Eu²⁺荧光粉。研究了材料的结构与光谱特性,分析了影响材料发光性能的工艺因素。结果表明,石墨粉含量和助熔剂的用量对Sr₂Si₅N₈相的形成和发光性能有重要影响。当n_C/n_Sr=1.5,助熔剂用量为4wt%时,合成样品的主晶相为正交晶系Sr₂Si₅N₈,在400~550 nm可见光激发下,可发射峰值波长位于609 nm荧光。激发带的位置与Eu²⁺离子浓度无关,为400~550 nm之间的宽带激发;但发射强度随Eu²⁺离子浓度的增加而增加,Eu²⁺离子浓度达到5mol%时发射强度达最大值,在Eu²⁺离子浓度为2mol%~5mol%之间,观察到发射峰的红移现象。     

非晶红色荧光粉Cd3Al2Si3O12∶Eu3+的制备及发光性能

使用溶胶-凝胶法制备了Cd₃Al₂Si₃O₁₂∶Eu³⁺非晶体系红色荧光粉,并对其发光性质进行了研究。该荧光粉在Eu³⁺的位于394 nm的⁵L₆能级和464 nm的⁵D₂能级的激发下能够产生强的⁵D₀→⁷F₂的红光特征发光,最佳掺杂摩尔分数为25%。Cd₃Al₂Si₃O₁₂∶Eu³⁺荧光粉与传统的Y₂O₃∶Eu³⁺相比较,其发光强度是Y₂O₃∶Eu³⁺的2.4倍左右(在394和464 nm的激发下)。Cd₃Al₂Si₃O₁₂∶Eu³⁺的热稳定性好,比已经商业化的YAG∶Ce³⁺的热猝灭影响要小得多。所有这些结果表明Cd₃Al₂Si₃O₁₂∶Eu³⁺可作为暖白光LED用红色荧光粉。     

Sr7Zr(PO4)6∶xEu2+蓝色荧光粉的合成及其发光特性

通过高温固相反应合成了新型的蓝色荧光粉Sr₇Zr(PO₄)₆∶xEu²⁺。通过X射线粉末衍射(XRD)、紫外可见(UV-Vis)吸收光谱、荧光光谱研究了Sr₇Zr(PO₄)₆∶xEu²⁺材料的相纯度及荧光性质。结果表明,Eu²⁺掺杂获得的Sr₇Zr(PO₄)₆∶xEu²⁺荧光粉为纯相,且200~400 nm范围内的近紫外(NUV)光均能对其进行有效的激发。在315 nm的激发下,Sr₇Zr(PO₄)₆∶xEu²⁺荧光粉发射出峰值位于415 nm左右的蓝光,且Eu²⁺在Sr₇Zr (PO₄)₆基质中的最佳掺杂浓度为0.05,相应的CIE色度坐标为(0.164,0.021),比商用BaMgAl₁₀O₁₇∶Eu²⁺(BAM)蓝色荧光粉具有更高的色纯度。     

空气中合成固溶体荧光粉Ba2(Zn, Mg)Si2O7:Ce3+,Eu2+,Eu3+及其发光特性

采用高温固相法在空气中合成了Ba_1.97-yZn_1-xMg_xSi₂O₇:0.03Eu,yCe³⁺系列荧光粉。分别采用X-射线衍射和荧光光谱对所合成荧光粉的物相和发光性质进行了表征。在紫外光330~360 nm激发下,固溶体荧光粉Ba_1.97-yZn_1-xMg_xSi₂O₇:0.03Eu的发射光谱在350~725 nm范围内呈现多谱峰发射,360和500 nm处有强的宽带发射属于Eu²⁺离子的4f⁶5d¹-4f⁷跃迁,590~725 nm红光区窄带谱源于Eu³⁺的⁵D₀-⁷F_J (J=1,2,3,4)跃迁,这表明,在空气气氛中,部分Eu³⁺在Ba_1.97-yZn_1-xMg_xSi₂O₇基质中被还原成了Eu²⁺;当x=0.1时,荧光粉Ba_1.97Zn_0.9Mg_0.1Si₂O₇:0.03Eu的绿色发光最强,表明Eu³⁺被还原成Eu²⁺离子的程度最大。当共掺入Ce³⁺离子后,形成Ba_1.97-yZn_0.9Mg_0.1Si₂O₇:0.03Eu,yCe³⁺荧光粉体系,其发光随着Ce³⁺离子浓度的增大由蓝绿区经白光区到达橙红区;发现名义组成为Ba_1.96Zn_0.9Mg_0.1Si₂O₇:0.01Ce³⁺,0.03Eu的荧光粉的色坐标为(0.323,0.311),接近理想白光,是一种有潜在应用价值的白光荧光粉。讨论了稀土离子在Ba₂Zn_0.9Mg_0.1Si₂O₇基质中的能量传递与发光机理。     

Eu2+掺杂KCaCl3晶体的生长及发光性能

通过坩埚下降法生长出不同物质的量分数Eu²⁺掺杂的KCa_1-xEu_xCl₃（x=0.005、0.01、0.02、0.03、0.05）单晶,并对晶体进行了X射线粉末衍射、热重、透过率、光致发光光谱、衰减时间、X射线激发发射光谱等测定。通过相图及结构分析,判断出该晶体为一致熔融化合物,并得出其为正交结构,晶胞参数为a=0.756 04 nm,b=1.048 23 nm,c=0.726 57 nm,空间群为Pnma（62）。在紫外光的激发下,晶体在434 nm左右有一个宽的发射峰,对应于Eu²⁺的4f⁶5d¹→4f⁷跃迁;光致衰减时间1.473 μs,晶体在X射线激发下的发光强度随Eu²⁺离子浓度增加而增强。     

绿色荧光粉Ca3Y2Si3O12:Tb3+,Ce3+的制备及发光特性

采用高温固相法合成了绿色荧光粉Ca₃Y₂Si₃O₁₂:Tb³⁺.XRD检测结果显示,荧光粉主晶相为Ca₃Y₂Si₃O₁₂,属单斜晶系.荧光光谱分析表明：Ca₃Y₂Si₃O₁₂:Tb³⁺硅酸盐荧光粉可以被370 nm的近紫外光激发,发射绿光,主发射峰位于490 nm(⁵D₄→⁷F₆),544 nm(⁵D₄→⁷F₅),585 nm(⁵D₄→⁷F₄)和621 nm(⁵D₄→⁷F₃).用544 nm最强峰监测,得到主激发峰位于370 nm的激发光谱,此光谱覆盖了300~450 nm的波长范围.研究了煅烧条件、掺杂浓度及Ce³⁺共掺杂对荧光粉发光性能的影响：在1 400 ℃下经二次煅烧 6 h得到的样品的发光性能最佳,Tb³⁺离子的最佳掺杂浓度为20mol%,Ce³⁺离子共掺杂能够提高荧光粉的发光强度,其最佳掺杂量为4mol%,说明存在Ce³⁺→Tb³⁺的能量传递.     

CaSb2O6:Bi3+,Eu3+荧光粉的制备和发光性质

采用共沉淀法及1 200 ℃后续煅烧4 h,成功制备了CaSb₂O₆:Bi³⁺,Eu³⁺荧光粉,并对其结构及发光性能进行了研究。所制备荧光粉颗粒为六边形类圆饼状,平均尺寸在100~600 nm之间。对CaSb₂O₆:Bi³⁺,Eu³⁺发光的机理分析表明,Bi³⁺对Eu³⁺的发光存在高效的敏化与能量传递。当Bi³⁺和Eu³⁺的掺杂浓度分别为0.5%和8%,Eu³⁺位于580 nm(⁵D₀→⁷F₀ )处的荧光发射显著增强,Bi³⁺,Eu³⁺共掺样品的荧光强度是CaSb₂O₆:Eu³⁺的10倍左右。调节Bi³⁺/Eu³⁺离子掺杂比,色坐标呈现了从蓝、白光到红光的变化,表明该荧光粉可分别作为蓝或红色荧光粉使用,甚至可实现从蓝、白光到红光的自由调控,这为白光LED荧光粉的发展提供了参考。     

红色发光长余辉材料Ca2SnO4∶Eu3+的性能研究

利用高温固相法合成了Ca₂SnO₄∶Eu³⁺红色发射长余辉发光材料,对样品进行了X射线衍射分析、荧光光谱分析、形貌分析以及发光寿命测量。分析结果表明,在1 350 ℃下烧结3 h的Ca₂SnO₄∶Eu³⁺为单相产物,所得Ca₂SnO₄∶Eu³⁺发光材料具有良好的发光性能,在267 nm紫外线激发下发出最强发射位于617 nm的锐线发射,并且具有明显的长余辉发光性能。     

沉淀法合成蓝色长余辉发光材料Sr2MgSi2O7∶Eu2+，Dy3+

采用沉淀法制备了高亮度的长余辉发光材料Sr₂MgSi₂O₇∶Eu²⁺,Dy³⁺。通过XRD、荧光光谱和热释光谱对其进行表征。XRD测试表明所制备的Sr₂MgSi₂O₇∶Eu²⁺,Dy³⁺为单相,四方晶。荧光光谱测试表明,用λ_em=467 nm作为监控波长,在275~450 nm之间有宽的激发光谱,峰值位于399 nm。用λ_ex=399 nm激发样品,其发射光谱为一宽带,峰值位于467 nm。1 050 ℃煅烧前躯体所制备的Sr₂MgSi₂O₇∶Eu²⁺,Dy³⁺发光性能最好。热释光谱峰值位于357 K,适合长余辉现象的产生。对Sr₂MgSi₂O₇∶Eu²⁺,Dy³⁺长余辉发光机理进行了讨论。     

KCl-KBO2-K2CO3, K2MoO4-KBO2-K2CO3, and K2WO4-KBO2-K2CO3 ternary systems

phase diagrams of KCl-KBO₂-K₂CO₃, K₂MoO₄-KBO₂-K₂CO₃, and K₂WO₄-KBO₂-K₂CO₃ ternary systems were studied by a calculation-experimental method and differential thermal analysis (DTA). The coordinates of ternary eutectics were determined to be E ₁: 622°C, 8.5 mol % KBO₂, 56.5 mol % KCl, and 35 mol % K₂CO₃; E ₂: 710°C, 23 mol % KBO₂, 43 mol % K₂CO₃, and 34 mol % K₂MoO₄; E ₃: 710°C, 23 mol % KBO₂, 43 mol % K₂CO₃, and 34 mol % K₂WO₄. The specific heats of melting of the eutectics were determined.     

Solubility in the Na2Cr2O7-(NH4)2Cr2O7-K2Cr2O7-H2O system

Solubility in the Na₂Cr₂O₇-(NH₄)₂Cr₂O₇-K₂Cr₂O₇-H₂O four-component water-salt system at 25, 50, and 75°C was studied for the first time. Phase field boundaries for individual salts and potassium and ammonium dichromate solid solutions, monovariant lines, and invariant points were determined. Experimental data were used to optimize the looped isohydric process of potassium dichromate preparation involving additional salts.     

Li2O-TiO2-SiO2-P2O5和Li2O-TiO2-Al2O3-P2O5体系锂离子固体电解质的制备及性能研究

一些具有NASICON型网格结构的固体电解质具有高的电导率和好的稳定性,NASICON的意思是Na Super Ionic Conductor[1]。当NaZr2(PO4)3中P5 被Si4 部分取代时便可以得到具有NASICON结构的Na1 xZr2SixP3-xO12体系,其具有高的钠离子电导率。然而有相同结构的Li1 xZr2SixP3-xO12体系的离子电导率却很低,这是因为Li 半径太小,而NASICON三维网格结构的离子通道太大,两者不匹配而使电导率下降[2]。但当LiZr2(PO4)3中Zr4 被离子半径小些的Ti4 取代,所得LiTi2(PO4)3的通道就与Li 半径相匹配,适合于锂离子的迁移,从而使其电导率…     

Li2SO4-Na2SO4-H2O和Li2SO4- K2SO4-H2O溶液的体积性质

本文用高精度数字式振荡管密度计测定了288K至318K温度范围内Li₂SO₄ + Na₂SO₄ + H₂O和 Li₂SO₄ + K₂SO₄ + H₂O三元体系的密度。混合溶液的离子强度范围从0.1到4.5 mol.kg_–1,混合溶液中Na₂SO₄和K₂SO₄的离子强度分数为0.2,0.4,0.6和0.8。用密度实验值拟合得到了不同温度下Pitzer离子相互作用模型混合参数θ_V和 ψ_V,模型的计算值与实验值的偏差在±0.002 g.cm_–3以内。用Pitzer模型计算了不同离子强度下三元体系的混合体积。     

The preparation of NbH5(Me2PCH2CH2Me2)2 and NbHL2(Me2PCH2CH2PMe2)2 (L = CO or C2H4)

MMe₅(dmpe) (M = Nb or Ta, dmpe = Me₂PCH₂CH₂PMe₂) reacts with H₂ (500 atm) and dmpe in THF at 60°C to give MH₅(dmpe)_2? NbH₅(dmpe)₂ readily reacts with two mol of CO or ethylene (L) to give NbHL₂(dmpe)₂. The exchange of the hydride ligand with the ethylene protons in NbH(C₂H₄)₂(dmpe)₂ is not rapid on the ¹H NMR time scale (60 MHz) at 95°C.     

(H2NC4H8NCH2CH2NH2)(HNCH2CH2NH2)3Zn2Ge2Se8: A new,templated one-dimensional ternary semiconductor stabilized by mixed organic cations

The novel, 1D semiconductor (H₂NC₄H₈NCH₂CH₂NH₂)(HNCH₂CH₂NH₂)₃Zn₂Ge₂Se₈ has been synthesized under solvothermal conditions using N-(2-aminoethyl)piperazine as solvent and templating agent at 200 °C. The material was characterized by single crystal and powder X-ray diffraction, IR and Raman spectroscopy and thermogravimetric analysis. The compound consists of 1D anionic [Zn₂Ge₂Se₈]⁴⁻ chains made of alternating edge-shared [ZnSe₄] and [GeSe₄] tetrahedra that charged balanced by one N-(2-aminoethyl)piperazinium and three piperazinium cations. The optical properties were investigated with solid state UV–Vis/near IR spectroscopy and the results show that the solid is a medium gap semiconductor with an absorption edge at 1.8 eV.     

NaBO2-NaCl-Na2CO3, NaBO2- Na2CO3-NaMoO4, NaBO2- Na2CO3-NaWO4, and NaBO2-NaCl-Na2WO4 ternary systems

The phase diagrams of the NaBO₂-NaCl-Na₂CO₃, NaBO₂-Na₂CO₃-Na₂MoO₄, NaBO₂- Na₂CO₃-Na₂WO₄, and NaBO₂-NaCl-Na₂WO₄ ternary systems were studied by a calculation-experimental method and differential thermal analysis. The coordinates of ternary eutectics were determined: E ₁: 612°C, 16 mol % NaBO₂, 42 mol % NaCl, and 42 mol % Na₂CO₃; E ₂: 568°C, 12 mol % NaBO₂, 28 mol % Na₂CO₃, and 60 mol % Na₂MoO₄; E ₃: 575°C, 12 mol % NaBO₂, 32 mol % Na₂CO₃, and 56 mol % Na₂WO₄; E ₄: 628°C, 8 mol % NaBO₂, 20 mol % NaCl, and 72 mol % Na₂WO₄; and E ₅: 655°C, 9 mol % NaBO₂, 53 mol % NaCl, and 38 mol % Na₂WO₄.     

Synthesis and characterization of inorganic solid electrolytes of Li2O-SiO2-P2O5 and Li2O-TiO2-SiO2-P2O5 systems

The lithium-ion-conducting inorganic solid electrolytes in the oxide systems Li₂O-SiO₂-P₂O₅ and Li₂O-TiO₂-SiO₂-P₂O₅ were prepared by the solid-state reaction, and the electrolyte pellet made by cold-pressing method had diameter of 13 mm and was about 1 mm thick. Phase identification and surface morphology of the products were carried out by X-ray diffraction and scanning electron microscopy. Ionic conductivity of the pellets was investigated through ac impedance. The results show that the adding of other cations can improve the ionic conductivity of the solid electrolyte, and the sintering temperature and duration can influence the ionic conductivity. The maximum ionic conductivity in the samples is 9.9 × 10⁻⁴ S/cm in the Li₂O-TiO₂-SiO₂-P₂O₅ system. Original Russian Text ? W. Li, M. Wang, Z.H. Li, X.F. Shang, H. Wang, Y.W. Wang, Y.B. Xu, 2007, published in Elektrokhimiya, 2007, Vol. 43, No. 11, pp. 1341–1345.     

Polymorphism in the Sc2Si2O7-Y2Si2O7 system

This paper examines the structural changes with temperature and composition in the Sc₂Si₂O₇-Y₂Si₂O₇ system; members of this system are expected to form in the intergranular region of Si₃N₄ and SiC structural ceramics when sintered with the aid of Y₂O₃ and Sc₂O₃ mixtures. A set of different compositions have been synthesized using the sol-gel method to obtain a xerogel, which has been calcined at temperatures between 1300 and 1750 °C during different times. The temperature-composition diagram of the system, obtained from powder XRD data, is dominated by the β-RE₂Si₂O₇ polymorph, with γ-RE₂Si₂O₇ and δ-RE₂Si₂O₇ showing very reduced stability fields. Isotherms at 1300 and 1600 °C have been analysed in detail to evaluate the solid solubility of the components. Although, the XRD data show a complete solid solubility of β-Sc₂Si₂O₇ in β-Y₂Si₂O₇ at 1300 °C, the ²⁹Si MAS-NMR spectra indicate a local structural change at x ca. 1.15 (Sc_2−xY_xSi₂O₇) related to the configuration of the Si tetrahedron, which does not affect the long-range order of the β-RE₂Si₂O₇ structure. Finally, it is interesting to note that, although Sc₂Si₂O₇ shows a unique stable polymorph (β), Sc³⁺ is able to replace Y³⁺ in γ-Y₂Si₂O₇ in the compositional range 1.86?x?2 (where x is Sc_2−xY_xSi₂O₇) as well as in δ-Y₂Si₂O₇ for compositions much closer to the pure Y₂Si₂O₇.     

Formation of [Cp2TiSbMe2]2, [Cp2TiSb(SiMe3)2]2 and [Cp2TiCl]2·2Mes4Sb2

Reactions of [Cp₂Ti(btmsa)] (btmsa = bis(trimethylsilyl)acetylene) with R₄Sb₂ (R = Me, Me₃Si) give [Cp₂TiSbMe₂]₂ (1) or [Cp₂TiSb(SiMe₃)₂]₂ (2) respectively. [Cp₂TiCl]₂·2Mes₄Sb₂ (3) is serendipitously formed from [Cp₂Ti(btmsa)] and Mes₂SbH containing NH₄Cl traces.