焰熔法生长钛酸锶单晶体生长室内温度分布的数值模拟

通过研究焰熔法生长钛酸锶单晶体过程中生长室内的温度分布特征,分析了H_2和O_2流量、喷嘴孔径对温度分布的影响。结果表明,采用焰熔法生长SrTiO_3晶体时,晶体熔帽表面温度和压力由中心逐渐向外降低;随着H_2流量的增加,中心轴向的最高温度的位置基本不变,晶体熔帽温度和晶体四周的最高温度逐渐升高,只是升高幅度有所减小;晶体熔帽温度、压力及晶体周围烟气温度随O_2流量增大而升高,而轴向最高温度则降低;增加喷嘴的中心孔径将使轴向最高温度、晶体熔帽温度和径向温度梯度降低,而喷嘴的H_2孔径对生长室内轴向和径向温度分布的影响不是很明显。     

二溴对甲基偶氮甲磺光度法测定钢中微量锶

研究了二溴对甲基偶氮甲磺与锶生成2:1兰色络合物进行钢中微量锶的测定.该法λ_(max)=638nm,摩尔吸光系数E_(638)=5.01×10~4,锶量在0.02～0.34μg/L范围内服从比尔定律.方法已用于钢中微量锶的测定,结果满意.     

Thermodynamic assessment of the La-Mg system

A thermodynamic modeling and optimization of the La-Mg system is carried out by means of the CALPHAD method taking into account the latest experimental results. The liquid, bcc-La, fcc-La, dhcp-La and hcp-Mg solutions are modeled as substitutional solutions (La, Mg) using the Redlich-Kister formalism. The LaMg, LaMg₂, La₅Mg₄₁, La₂Mg₁₇ and LaMg₁₂ phases are treated as stoichiometric compounds, and the non-stoichiometry of LaMg₃ is described as (La,Mg)_0.25Mg_0.75. The results are in good agreement with the set of experimental data which were carefully discussed and selected.     

NOx adsorption behavior of LaFeO3 and LaMnO3+δ and its influence on potentiometric sensor response

NO_x adsorption behavior on LaFeO₃ (LFO) and LaMnO_3+δ (LMO) was characterized using temperature controlled methods and mass spectrometry. Temperature program desorption revealed decomposition of complex surface species formation when NO or NO₂ was adsorbed on LFO and LMO. LFO exhibited higher adsorption capacity for NO_x species than LMO and was shown to be more active for NO_x surface conversion. Both effects were attributed to the different B-site cations, with iron in LFO in the 3+ valence state, and manganese in LMO in the 3+ and 4+ valence states. Results from diffuse reflectance infrared spectroscopy were used to identify specific nitrite and nitrate species that are formed on the surfaces of LFO and LMO at room temperature. Temperature programmed reaction revealed a complex NO₂ decomposition mechanism to NO and O₂ for LFO and LMO in which the formation of nitrite and nitrate species serve as intermediates below ∼600 °C. NO_x sensing mechanisms were considered and predicted based on the types and quantities of surface species formed.     

锶在改性介质中迁移的柱实验研究

通过室内土柱实验研究了锶在不同润湿性介质中的迁移规律和特征,并采用CXTFIT 2.1软件对实验结果进行了拟合,通过实验数据计算了延迟因子。结果表明：在疏水介质中,锶的穿透速度较快,利用平衡CDE方程或两区模型来模拟锶在三种润湿性不同的石英砂柱中的迁移均是可行的,但两区模型的模拟效果更好。     

钙钛矿结构锰氧化物Pr_(1-x)Ca_xMnO_3(0.4≤x≤0.5)纳米材料的磁性质研究

采用溶胶凝胶法制备了Pr1-xCaxMnO3(0.4≤x≤0.5)系列纳米样品,对其磁性质进行了研究.所有样品在M-T曲线中250K附近的电荷有序转变和170K附近的顺磁-反铁磁转变都消失,与Dong等人的理论模拟计算相符.所有样品在40K都出现了Reentrant spin glass(RSG)态.随着Ca2+掺杂浓度的增加,Mn3+/Mn4+的比例迅速变小,破坏了Mn-O-Mn导电通道,导致磁化强度M逐渐变小.     

均匀设计法筛选SBLC涂复料的化学配方

采用均匀设计法对ＳｒＴｉＯ３晶界层电容器（ＳＢＬＣ）的二次烧结涂复料配方进行筛选。研究了ＰｂＯ－Ｂｉ２Ｏ３－ＣＵＯ－Ｂ２Ｏ３四元体系不同配方涂复料对电容器的介电常数及损耗的影响。经回归分析得到涂复料的较优配方是：Ｐｂｏ：Ｂｉ２Ｏ３：ＣｕＯ：Ｂ２Ｏ３：８．３：５．６：１：６．３     

草酸盐共沉淀法制备SrAl2O4：Eu^2＋，Dy^3＋发光粉体的研究

用草酸盐共沉淀法制备了SrAl2O4：Eu^2＋，Dy^3＋发光粉体，用差热分析仪、X-射线衍射仪、扫描电镜和荧光分光光度计对制备产物进行了测试分析，并对烧成温度，Dy^3＋、H3BO3掺杂对荧光体发光特性的影响进行了讨论，确定了草酸盐共沉淀法的最佳烧成温度为1200℃，Dy^3＋最佳掺杂摩尔分数为0．002，硼酸为0．3。     

Hemocompatibility of lanthanum oxide films fabricated by dual plasma deposition

Lanthanum oxide films were fabricated using dual plasma deposition. X-ray photoelectron spectroscopy (XPS) showed that La existed in the + 3 oxidation state. X-ray diffraction (XRD) revealed a (101) oriented hexagonal structure. Blood platelet adhesion tests and endothelial cell cultures were used to evaluate the hemocompatibility of the as-deposited films. Scanning electron microscopy (SEM) and optical microscopy were employed to evaluate the surface morphology of the blood platelets and endothelial cells on the films. The results showed that the number of adhered, aggregated and morphologically changed platelets was reduced compared to that observed on low-temperature isotropic carbon (LTIC). Endothelial cells culture tests indicated good adhesion and proliferation of human umbilical vein endothelial (HUVE) cells in vitro. Our study suggests that lanthanum oxide films are potential blood-contacting biomedical materials.     

Study on BSTO/MgO Ferroelectric Materials for Phase Shift Doped with Rare Earth Oxides

Phasedarrayantennascansteerthetransmitted orreceivedsignalswiththeadvantagesoffastscan ning,multipletargetstrackingandgoodanti jam ming.Theseantennasarecurrentlyconstructedusing ferritephaseshiftingelements,whicharecostly,large andheavy.Therefore,theirmil…