Sr和Ba替代对Eu掺杂Ca2.955Si2O7的结构和发光特性的影响研究

利用固相反应法制备了Sr和Ba替代的Ca_2.955-xM_xSi₂O₇: 0.045Eu²⁺ (M= Sr, Ba, x= 0.1-0.5)系列荧光粉, 利用较大离子半径的Sr和Ba元素替代Eu掺杂Ca_2.955-xM_xSi₂O₇ 中的Ca元素,研究Sr和Ba替代对样品结构和发光特性的影响. X射线衍射测试结果表明,少量Sr和Ba替代不会改变基质的晶体结构, 样品仍然为单斜晶系.未替代前, Ca_2.955Si₂O₇: 0.045Eu²⁺ 样品的发射峰在574 nm左右,随着Sr含量的增加,样品的发射峰发生蓝移; 而Ba含量在x= 0.1-0.4时不会引起发射峰位置的移动, 但x= 0.5样品的发射峰发生蓝移.同等含量的Sr和Ba部分替代样品中的Ca元素, Ba替代样品的光谱强度较强.     

焙烧温度对钛酸钙光催化性能的影响

以CaCO3和TiO2为原料,分别在1 100,1 200,1 300,1 400,1 500℃条件下进行焙烧.应用XRD,SEM,FT-IR,UV-vis对处理后的物料进行表征.实验结果表明,1 400℃以上能够合成出纯CaTiO3;随着温度提高,颗粒微观形貌从不规则多边形向光滑曲面形变化,团聚现象趋于明显;CaTiO3和TiO2含量不同导致催化剂在紫外-可见光区域光吸收能力有较大不同.在光催化性能评价实验中,随着温度提高,亚甲基蓝降解率和降解速率均降低,反应速率常数降低幅度达50%;钛酸钙降解亚甲基蓝溶液比较符合一级反应动力学特征.     

Titanium‐mediated living radical styrene polymerizations. V. Cp2TiCl‐catalyzed initiation by epoxide radical ring opening: Effect of solvents and additives

The effects of solvents, additives, ligands, and solvent in situ drying agents as well as catalyst and initiator concentrations have been investigated in the Cp₂TiCl‐catalyzed radical polymerization of styrene initiated by epoxide radical ring opening. On the basis of the solubilization of Cp₂Ti(III)Cl and the polydispersity of the resulting polymer, the solvents rank as follows: dioxane ≥ tetrahydrofuran > diethylene glycol dimethyl ether > methoxybenzene > diphenyl ether ≥ bulk > toluene ? pyridine > dimethylformamide > 1‐methyl‐2‐pyrrolidinone > dimethylacetamide > ethylene carbonate, acetonitrile, and trioxane. Alkoxide additives such as aluminum triisopropoxide and titanium(IV) isopropoxide are involved in alkoxide ligand exchange with the epoxide‐derived titanium alkoxide and lead to broad molecular weight distributions, whereas similarly to strongly coordinating solvents, ligands such as bipyridyl block the titanium active site and prevent the polymerization. By contrast, softer ligands such as triphenylphosphine improve the polymerization in less polar solvents such as toluene. Although mixed hydrides such as lithium tri‐tert‐butoxyaluminum hydride, sodium borohydride, and lithium aluminum hydride react with bis(cyclopentadienyl)titanium dichloride to form mixed titanium hydride species ineffective in polymerization control, simple hydrides such as lithium hydride, sodium hydride, and especially calcium hydride are particularly effective as in situ trace water scavengers in this polymerization. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2015–2026, 2006     

硫酸铝在纤维增强轻质硅酸钙材料中的作用机理

通过试验证明，加入适量硫酸铝对于溶解乙气瓶填料具有如下作用：在料浆阶段能够促进料浆凝胶化，防止物料下沉；在蒸压过程中能够产生微膨胀，防止填料收缩，并能够使填料强度显著提高。同时，采用ＤＴＡ、ＸＲＤ、ＳＥＭ方法对其作用机理进行了研究。     

电石炉炉气净化系统的分析

对一种新型的电石炉炉气干法净化系统的组成、主要设备的作用和性能进行了详细的分析．     

高纯硅石中微量铁钙的原子吸收光谱分析

提出了高纯硅石的溶样方法和微量铁钙的火焰原子吸收光谱分析条件，采用标准加入法，既能避免强烈的背景影响，又能克服严重的基体干扰，结果准确可靠，铁钙的精密度分别为４．９％和５．５％回收率在９２％￣１０２％。     

锌钙系防锈磷化工艺

研究了锌钙系磷化工艺.以磷化膜质量和防锈性为定量指标,讨论了操作参数(总酸度、游离酸度、温度、时间和酸比)对磷化膜的影响,确定了最佳磷化工艺.结果表明:该磷化工艺稳定,维护简单,所得磷化膜防锈性优良.由磷化机理分析表明,磷化膜的组成为Zn3(PO4)2和Ca3(PO4)2.     

ESR studies of Cu2+ doped in triglycine calcium bromide single crystals

Electron spin resonance studies were carried out on Cu²⁺ doped triglycine calcium bromide. The spectra recorded at room temperature revealed well-resolved hyperfine spectra of⁶³Cu superposed with super-hyperfine lines due to¹⁴N nuclei. The spin Hamiltonian parameters are evaluated. It was concluded that the Cu²⁺ enters the lattice interstitially.