Ca_(1-x)Zn_xTiO_3∶Pr~(3+)的固溶特性及其发光性能

通过高温固相合成法制备了名义组成为Ca1-xZnxTiO3∶0.002Pr3+(x=0.0~0.20)的红色发光材料,采用XRD和光谱等手段研究微量Zn掺杂的单相Ca1-xZnxTiO3∶0.002Pr3+材料的晶体结构参数与发光性能,分析了等价Zn2+的掺杂对固溶体结构参数与发光性能的影响规律。结果表明,在x≤0.01微量Zn掺杂时,Zn取代Ca形成单相Ca1-xZnxTiO3∶0.002Pr3+固溶;其晶胞参数和晶胞体积,260和330 nm两激发带以及610nm发射峰强度均随Zn掺量增加快速减小,且发光强度与晶胞参数的变化规律相吻合。分析表明这种变化与Zn取代Ca形成的固溶结构有关。     

Ca_(1-x)Zn_xTiO_3∶Pr~(3 ),R~ (R~ =Li~ ,Na~ ,K~ ,Rb~ ,Cs~ ,Ag~ )的合成和发光性质

采用X射线衍射、荧光光谱和热释发光研究了Ca1 -xZnxTiO3∶Pr3 ,R 的物相组成和发光性质。Pr3 取代Ca2 形成PrCa·正电性缺陷发光中心。激发光谱是峰值位于 3 3 0nm附近的宽带谱 ,发射光谱是峰值在 613nm半宽度为 2 0nm的带谱 ,对应Pr3 的1 D2 -3H4 跃迁发射。发光强度和余辉随基质组分Zn/Ca摩尔比和合成温度而变化。Zn2 的最佳含量在 10 %～ 2 0 %。X射线衍射研究表明掺入适量的Zn2 物相组成为CaTiO3,Ca2 Zn4 Ti1 5O36 和Zn2 TiO4 。热释发光曲线表明掺入Zn2 离子后体系中形成了新的缺陷ZnTi″ ,且ZnTi″的缺陷陷阱深度大于RCa′。     

一类新的红色荧光粉MYzS4：Er^3＋（M=Srz＋，Ba^2＋）的合成与表征

Eu^2＋激活的CaS：Eu^[1],Eu^3＋和Sm^3＋激活的硫氧化物^[2]，Pr^3＋激活的Ca0.8Zn0.2Ti03^[3]以及Eu^2＋和Mn^2＋掺杂的SrY2S4^[4]都是重要的红色发光材料。然而，这些红色荧光粉的发射峰波长都短于650nm，对于农用日光转换材料^[5]，红色发射峰波长达到660nm才能与叶绿素的红区吸收相吻合。     

Ca1—xZnxTiO3：Pr^3＋,R^＋（R^＋=Li^＋,Na^＋,K^＋,Rb^＋,Cs^＋,Ag^＋）的合成和发光性质

采用X射线衍射、荧光光谱和热释发光研究了Ca1-xZnxTiO 3∶Pr3+, R+的物相组成和发光性质. Pr3+取代Ca2+形成PrCa ·正电性缺陷发光中心. 激发光谱是峰值位于330 nm附近的宽带谱, 发射光谱是峰值在613 nm半宽度为20 nm的带谱, 对应Pr3+的1D2-3H4跃迁发射. 发光强度和余辉随基质组分Zn/Ca摩尔比和合成温度而变化. Zn2+的最佳含量在10%～20%. X射线衍射研究表明掺入适量的Zn2+物相组成为CaTiO3, Ca2 Zn4Ti15O36和Zn2TiO4. 热释发光曲线表明掺入Zn2+离子后体系中形成了新的缺陷ZnTi″, 且ZnTi″的缺陷陷阱深度大于RCa′.     

蓝色长余辉材料CaAl_2O_4∶Eu~(2+),Nd~(3+)的合成及其发光性能

采用高温固相法合成了系列单相Ca(1-x-y)A l2O4∶Eux2+,Ndy3+(0≤x≤0.045,0≤y≤0.0037)粉末样品,并表征了其发光特性.研究结果表明,样品的发射光谱为最大发射峰位于440 nm的宽带谱,属于Eu2+的4f65d→4f7跃迁.通过对Eu2+,Nd3+掺杂量与样品发光性能之间关系的研究发现,Eu2+和Nd3+最佳掺杂量分别为x=0.001 25和y=0.002 5,并且Nd3+对改善蓝色长余辉材料CaA l4∶Eu2+的余辉性能具有重要的作用.在最佳掺杂条件下,样品的余辉时间可达1 000 m in,初始亮度大于1 200 m cd/m2,60 m in后发光粉的亮度仍然在10 m cd/m2以上.利用正电子湮灭技术和热释光技术,研究了Eu2+和Nd3+对CaA l2O4∶Eu2+,Nd3+材料的发光性能的影响.     

Sr2.975-xCaxAlO4F∶Ce3+0.025荧光粉的制备及发光性能研究

采用高温固相法制备了Sr2.975-xCaxAlO4F:Ce3+0.025(0≤x≤1.0)发光材料,通过X射线衍射、荧光光谱测试分析,研究了Ca2+掺杂对晶体结构和发光性能的影响.XRD测试表明Ca2+的掺入并没有改变基质晶格的结构类型,且在Sr3 AlO4F基质中固溶极限不超过x=0.9.荧光光谱分析表明,Ca2+掺入后能有效提高发光强度,使激发光谱宽化和发射光谱红移,在Ca2+掺入量为x=0.4时发射强度最高.考察了Sr3-xCaxAlO4F:Ce3+(x =0,x=0.4)在不同Ce3+浓度的发射强度与峰值波长,发现Ca2+掺杂量由x=0增加至x=0.4时,对应的Ce3+的猝灭浓度由0.01降低至0.0025,并且Ce3+的猝灭机制为电偶极-电偶极相互作用.     

Yb3+共掺杂对Zn2GeO4:Mn2+绿色长余辉发光性能增强研究

利用高温固相法合成了Zn2GeO4:Mn2+以及Zn2GeO4:Mn2+,Yb3+绿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、色坐标、热释发光以及发光寿命测量.分析结果表明,在1050℃下烧结3h的Zn2CeO4为单相产物,所得Zn2GeO4:Mn2+发光材料具有良好的发光性能,在紫外灯激发下发出最强发射位于528 nm的宽带发射并具有优良的长余辉发光特性,其色坐标值分别为x=0.145,y=0.773.Yb3+共掺杂对其长余辉发光性能提高明显.余辉发光在暗场环境下肉眼可观察的持续时间超过2h.通过热释光谱对陷阱进行了分析.对Yb3+共掺杂的长余辉发光增强机理进行了讨论.     

红色长余辉发光材料Ca2Zn4Ti15O36：Pr^3＋的合成和发光性质

分别采用高温固相法和溶胶-凝胶法合成了新型红色长余辉发光材料Ca2Zn4Ti15O36:Pr。高温固相法合成Ca2Zn4Ti15O36需要在1200℃灼96h才能形成纯物相。热重分析曲线和X射线衍射分析结果表明：溶胶-凝胶法制得的前驱体在700℃灼烧12h开始形成Ca2Zn4Ti15O36物相；在1000℃灼烧24h得到Ca2ZnTi15O36纯物相；最佳反应温度为1000℃，激活剂Pr^3 的最佳浓度为0．6mol％，发光强度比高温固相法增强了510％。     

Yb3+共掺杂对Zn2GeO4∶Mn2+绿色长余辉发光性能增强研究

利用高温固相法合成了Zn2GeO4∶Mn2+以及Zn2GeO4∶Mn2+,Yb3+绿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、色坐标、热释发光以及发光寿命测量。分析结果表明,在1 050℃下烧结3 h的Zn2GeO4为单相产物,所得Zn2GeO4∶Mn2+发光材料具有良好的发光性能,在紫外灯激发下发出最强发射位于528 nm的宽带发射并具有优良的长余辉发光特性,其色坐标值分别为x=0.145,y=0.773。Yb3+共掺杂对其长余辉发光性能提高明显。余辉发光在暗场环境下肉眼可观察的持续时间超过2 h。通过热释光谱对陷阱进行了分析。对Yb3+共掺杂的长余辉发光增强机理进行了讨论。     

白光LED用荧光材料Ba3Gd（BO3）3∶Eu^（3＋）的发光性能研究

用高温固相反应法制备了稀土离子Eu^3＋掺杂的三元稀土硼酸盐Ba3Gd（BO3）3发光材料,通过X射线衍射（XRD）、荧光光谱和扫描电镜（SEM）等测试手段对Ba3Gd（BO3）3∶Eu^3＋荧光粉的制备条件、发光性能以及形貌进行了研究。XRD结果表明,在1000℃时可得到Ba3Gd（BO3）3纯相。扫描电镜照片显示颗粒基本为球形,粒径约为200-400 nm。发光光谱测试表明,Ba3Gd（BO3）3∶Eu^3＋荧光粉在近紫外区（UV）（396 nm）和蓝光区（466 nm）可以被有效地激发,分别用255和396 nm的紫外光激发样品时,以Eu3＋的5D0-7F2（611和616 nm）超灵敏跃迁为主要发射峰。当Eu3＋的掺杂浓度为10%（摩尔分数）时,Ba3Gd（BO3）3∶Eu3＋在611和616 nm处的发光强度最大。因此,这种荧光粉是一种可能应用在白光LED上的红色荧光材料。     

Ca4IrO6, Ca3MgIrO6 and Ca3ZnIrO6

Single crystals of tetracalcium iridium hexaoxide, Ca₄IrO₆, tricalcium magnesium iridium hexaoxide, Ca₃MgIrO₆, and tricalcium zinc iridium hexaoxide, Ca₃ZnIrO₆, were prepared via high-temperature flux growth and structurally characterized by single-crystal X-ray diffraction. The three compounds are isostructural and adopt the K₄CdCl₆ structure type, comprised of chains of alternating face-shared [CaO₆], [MgO₆] or [ZnO₆] trigonal prisms and [IrO₆] octahedra, surrounded by columns of Ca²⁺ ions.     

Reindarstellung und thermische Stabilität von Calcium-phosphid- und -arsenidiodiden: Ca3PI3, Ca3AsI3, Ca2PI und Ca2AsI

Preparation and Thermal Stability of Calcium Phosphide and Arsenide Iodides: Ca₃PI₃, Ca₃AsI₃, Ca₂PI, and Ca₂AsI Ca₃PI₃ and Ca₃AsI₃ (colourless) as well as Ca₂PI and Ca₂AsI (greenish yellow) were prepared purely by reaction of “Ca₃P₂” and “Ca₃As₂” resp. with CaI₂ in the molar ratios 1:3 and 1:1 resp. in steel ampoules under argon at 800°C and 1 000°C resp. Analytical results, lattice constants, and densities of the compounds are given. They don't possess a homogeneity range. Ca₃PI₃ and Ca₃AsI₃ begin to decompose reversibly at 950 and 1 000°C resp. by forming Ca₂PI and Ca₂AsI resp. and CaI₂. Ca₂PI is yet stable at 1 200°C and Ca₂AsI at 1100°C.     

Ca3Mn2O7

The tricalcium dimanganese heptaoxide (Ca₃Mn₂O₇) member of the Ruddlesden–Popper series Ca_n+1Mn_nO_3n+1, i.e. with n = 2, was previously reported with an I‐centred tetragonal lattice [a_t = 3.68 and c_t = 19.57 Å] by Fawcett, Sunstrom, Greenblatt, Croft & Ramanujachary [Chem. Mater. (1998), 10 , 3643–3651]. It is now found to be orthorhombic, with an A‐­centred lattice [a = 5.2347 (6), b = 5.2421 (2) and c = 19.4177 (19) Å]. The structure has been refined in space group A2₁am using X‐ray single‐crystal diffraction data and assuming the existence of twin domains related by the (10) plane. A comparison with the basic perovskite structure CaMnO₃ (n = ∞) is proposed.     

Zur Kenntnis von Ca3IrCuO6

On Ca₃IrCuO₆ Single crystals of Ca₃IrCuO₆ were prepared by a flux technique and investigated by single crystal X-ray work. It crystallizes with monoclinic symmetry, space group C—C12/c1; a = 9.032, b = 9.295, c = 6.466 Å, β = 91.35°, Z = 4. Ca₃IrCuO₆ is isotypic to Sr₃IrCuO₆. The square planare CuO₄ polygones show probably a slightly deficit accompanied by an adequate part of iridium in the oxydation state Ir⁵⁺.     

Thermodynamic properties of calcium titanates: CaTiO3, Ca4Ti3O10, and Ca3Ti2O7

The chemical potentials of CaO in two-phase fields (TiO₂ + CaTiO₃), (CaTiO₃ + Ca₄Ti₃O₁₀), and (Ca₄Ti₃O₁₀ + Ca₃Ti₂O₇) of the pseudo-binary system (CaO + TiO₂) have been measured in the temperature range (900 to 1250) K, relative to pure CaO as the reference state, using solid-state galvanic cells incorporating single crystal CaF₂ as the solid electrolyte. The cells were operated under pure oxygen at ambient pressure. The standard Gibbs free energies of formation of calcium titanates, CaTiO₃, Ca₄Ti₃O₁₀, and Ca₃Ti₂O₇, from their component binary oxides were derived from the reversible e.m.f.s. The results can be summarised by the following equations: CaO(solid) + TiO₂(solid) → CaTiO₃(solid), ΔG° ± 85/(J · mol^?1) = ?80,140 ? 6.302(T/K); 4CaO(solid) + 3TiO₂(solid) → Ca₄Ti₃O₁₀(solid), ΔG° ± 275/(J · mol^?1) = ?243,473 ? 25.758(T/K); 3CaO(solid) + 2TiO₂(solid) → Ca₃Ti₂O₇(solid), ΔG° ± 185/(J · mol^?1) = ?164,217 ? 16.838(T/K).The reference state for solid TiO₂ is the rutile form. The results of this study are in good agreement with thermodynamic data for CaTiO₃ reported in the literature. For Ca₄Ti₃O₁₀ Gibbs free energy of formation obtained in this study differs significantly from that reported by Taylor and Schmalzried at T = 873 K. For Ca₃Ti₂O₇ experimental measurements are not available in the literature for direct comparison with the results obtained in this study. Nevertheless, the standard entropy for Ca₃Ti₂O₇ at T = 298.15 K estimated from the results of this study using the Neumann–Koop rule is in fair agreement with the value obtained from low-temperature heat capacity measurements.