Formation of palladium nanoparticles in poly (o-methoxyaniline) macromolecule fibers: An in-situ chemical synthesis method

We report here a novel in-situ synthetic method for the preparation of poly (o-methoxyaniline) and palladium nanoparticle composite material. Ortho-Methoxyaniline and palladium acetate were used as the precursors; during the reaction o-methoxyaniline was oxidized and forms poly (o-methoxyaniline) and palladium acetate is reduced forming palladium nanoparticles. IR and Raman spectra provide information on the structure of the polymer. The TEM and SEM analysis are used to determine the size of the nanoparticles and the morphology of the polymer respectively.     

Synthesis,crystal structure and magnetic characterization of Pr3+ and Zn2+ ions co-doped hexagonal ferrites via the ceramic process

M-type hexaferrites Ca_0.2Sr_0.8-xPr_xFe_12-yZn_yO₁₉ (0.00?≤?x?≤?0.40, 0.00?≤?y?≤?0.30) were synthesized by the ceramic process. The X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and a vibrating sample magnetometer (VSM) were used to investigate microstructure and magnetic properties of the M-type hexaferrites. The single-phase with hexagonal structure was obtained in all Pr–Zn substituted M-type hexaferrites, and with increasing Pr–Zn content, the 2θ values of (107) and (114) peaks shifted towards higher angles. With increasing Pr–Zn content, the lattice constant a basically kept unchanged, while the lattice constant c decreased. FESEM images of the hexaferrites showed that the hexagonal platelets had formed in the hexaferrites and the average grain size increased with increasing Pr–Zn content. The saturation magnetization (M_s), remanent magnetization (M_r) and M_r/M_s ratio first increased with increasing Pr–Zn content (0.00?≤?x?≤?0.24, 0.00?≤?y?≤?0.18), and then decreased with further increasing Pr–Zn content. The coercivity (H_c), magnetic anisotropy field (H_a) and effective magnetic anisotropy constant (K_eff) increased with increasing Pr–Zn content (0.00?≤?x?≤?0.16, 0.00?≤?y?≤?0.12), and then decreased with further increasing Pr–Zn content.     

Y_(1-x)Pr_xBa_2Cu_3O_(7-δ)单晶的生长与退火效应研究

采用顶部籽晶提拉法成功生长出了Y1-xPrxBa2Cu3O7-δ(x=0.07215,0.23960)单晶样品。利用X射线结构分析技术对生成单晶进行了表征,通过对样品进行了不同时间的退火处理,结合超导磁化特性测量,讨论了单晶样品超导转变温度Tc随退火温度和Pr替代含量的变化,并根据单晶样品磁化特性曲线,从低场下的布拉格玻璃态到高场下的磁通玻璃态的相变角度对尖峰效应进行了初步分析。     

Pr3+掺杂硒基玻璃的制备及其中红外发光性能增强研究

报道了一种可用于2μm商用激光器有效激发的中红外宽带发光玻璃. 采用真空熔融淬冷法制备了Pr3+掺杂硒基玻璃的系列样品, 测试了样品的吸收光谱以及2μm激光泵浦下的3~5μm中红外荧光光谱, 观察到了由激发态吸收造成的近红外荧光. 通过Judd-Ofelt理论计算了不同浓度Pr3+离子掺杂玻璃样品的强度参数Ωt (t=2, 4, 6)、辐射寿命和受激发射截面等光谱参数, 讨论Pr3+离子局域配位环境对发光特性的影响. 结果表明, 4.6μm和4.8μm对应的跃迁能级具有较好的发光特性, 相比其他体系玻璃具有更大的受激发射截面, 是一种理想的中红外激光基质材料.     

锌锅中低Pr流体混合对流的数值模拟

以带钢连续热镀锌生产工艺为背景,对抽象出的低Pr数流体混合对流流动和换热模型进行了数值模拟,给出了在不同Re、Ra及Ri时的流场和温度场.数值结果表明,当Re、Ra都不等于0时,在所考虑的参数范围内,流动和换热受自然对流和强制对流两种机理控制.Re不变,增大Ri,自然对流作用加强,并且当Ri增加到一定值时,流动和换热发生振荡.所给出的速度相图显示,对应不同的Re、Ra及Ri,流动和换热会出现稳态解、周期性振荡解和混沌.     

锌锅中低Pr流体混合对流的自维持振荡

本文对以带钢连续热镀锌为背景抽象出的锌锅中低Pr流体的流动和传热进行了数值模拟.数值结果显示,对Re=0的纯自然对流,Ra在104和105间时数值解由稳态解分岔为振荡解;对于Ra=0的纯强制对流,Re在4×103和5x1003之间时,数值解从稳态解分岔为振荡解;当Ra和Re均小于自然对流和强制对流单一机制作用时发生振荡的临界值时,混合对流的流动和传热为稳态;当Ra和Re中的一个参数大于单一机制作用发生振荡的临界值时,另一个参数由小于增加到大于单一机制作用发生振荡的临界值时,数值解由振荡解变为稳态解.     

退火温度对纳米晶ZrO2发光和ZrO2:Pr3+能量传递的影响

利用共沉淀法制备了纳米晶ZrO2和ZrO2:Pr3+,通过XRD对材料的晶体结构、颗粒尺寸进行了表征,研究了退火温度对纳米晶ZrO2发光性质的影响,探讨了ZrO2的发光机制,研究了退火温度对ZrO2∶ Pr3+能量传递的影响,给出了基质ZrO2与Pr3+离子间的能量传递模型.结果表明:随着退火温度的提高,纳米晶ZrO2由四方相转变为单斜相,颗粒尺寸增大;ZrO2的发射谱是一个中心位于470 nm的宽带,发光强度随退火温度升高而增强;基质ZrO2向激活离子Pr3+的能量传递方式为无辐射过程,高温退火有利于基质向Pr3+离子的能量传递,这种现象与退火温度对纳米晶ZrO2发光性质的影响有关.     

稀土(La3+,Pr3+)-DBS-偶氮胂有色配合物组成和稳定常数的吸收光谱法测定

稀土 (La3 + ,Pr3 + )在酸性条件下与DBS 偶氮胂发生配位反应。首先对光谱数据进行因子分析法处理从而判断出只生成一类配合物 ,进而采用线性回归法计算配合物组成、摩尔吸光系数、表观稳定常数及配位体浓度。实验结果表明 :在 1mol·L-1HCl介质中 ,La3 + 、Pr3 + 与DBS 偶氮胂形成M∶L =1∶3的配合物 ,其摩尔吸光系数分别为 1 399× 10 5和 1 5 17× 10 5L·mol-1·cm-1,表观稳定常数logβ3 分别为 15 36和 15 34。     

溶胶-凝胶法制备Zn3Ga2Ge2O10:Cr3+0.01,Pr3+0.03,Yb3+0.3纳米长余辉材料及其表面修饰的研究

以Ga(NO3)3·8H2O、Zn(NO3)2·6H2O、Pr(NO3)2·6H2O、GeO2、Yb(NO3)3·5H2O、Cr(NO3)2·9H2O为原料,采用溶胶-凝胶法合成了Cr3+,Pr3+,Yb3+共掺杂的Zn3Ga2Ge2O10长余辉纳米材料(PLNPs).利用XRD,SEM,激发发射图谱,余辉曲线测试确定1000℃煅烧,保温3 h时,基质Zn3 Ga2 Ge2 O10已形成.Yb3+掺杂百分比为0.3时,样品的发光性能最好.Zn3 Ga2 Ge2 O10:Cr3+0.01,Pr3+0.03,Yb3+0.3纳米长余辉材料在波长为267 nm的紫外线激发下发射出中心波长为745 nm的深樱桃红色光,此时晶粒粒径约为150 nm;随着Yb3+掺杂百分比的增加,晶粒粒径逐渐变小.通过FT-IR,Zeta电势,激光粒度测试,TEM及悬浮实验测试表明,PEG修饰PLNPs后,可观察到明显的核壳结构,水合粒径约为155 nm;水溶性大大增加,0.3 mg/mL的浓度下其悬浮时间超过48 h,这表明PEG包裹PLNPs成功.     

A Synergistic Effect of Select Organotin Compounds and Ionic Surfactants on Liposome Membranes

Organometallic compounds and surfactants constitute a potential threat to the environment. For that reason we have embarked on a study of their joint action on membranes. Model lecithin liposome membranes were modified with the cationic surfactant trimethyldodecylammonium bromide or the anionic surfactant sodium dodecylsulfonate, and the effect of tripropyltin chloride on the process of calcium (Ca²⁺) and praseodymium (Pr³⁺) desorption from the liposome membrane was studied. Kinetic constants for the process of Ca²⁺ ion desorption from lecithin liposome membranes were determined using the radiotracer method. The percentage of Pr³⁺ ion desorption from liposome membranes was measured by the ¹H NMR method. Trimethyltin, triethyltin and tripropyltin alone caused increased Ca²⁺ and Pr³⁺ desorption from liposome membranes with increasing concentration of the compounds and alkyl chain length. For both the processes studied, a cationic surfactant brought about a lower effectiveness of tripropyltin and an anionic surfactant resulted in a higher effectiveness. The effect observed can be explained by changes in the surface charge of the membrane, induced by the surfactant modifiers and by the concomitant change in the partition coefficient of the organotin. The results obtained indicate a protective or harmful joint action of the surfactants used with tripropyltin on membranes. © 1997 John Wiley & Sons, Ltd.