纳米晶复合永磁铁氧体的双相交换耦合作用

采用sol-gel方法制备纳米晶复合SrFe12O19/γ-Fe2O3铁氧体.利用X射线衍射(XRD),透射电子显微镜(TEM)和振动样品(VSM)对纳米晶样品进行了研究.当焙烧温度介于600～800℃,样品存在SrFe12O19/γ-Fe2O3复相.在同样条件下,压成薄片的样品呈现了硬磁与软磁(SrFe12O19/γ-Fe2O3)的纳米复合相的交换耦合作用.对SrFe12O19/γ-Fe2O3的纳米复合材料的各向同性磁能积的增加和磁性交换耦合作用机制进行了研究.     

皖北矿区煤层底板岩溶水氢氧稳定同位素特征

对皖北矿区主要含水层的氢氧稳定同位素进行了测试与分析,岩溶含水层中太原组石灰岩岩溶裂隙水(简称"太灰水")δ(18O)均值为-8.69‰,δD均值为-68.64‰,奥陶系石灰岩裂隙溶隙水(简称"奥灰水")δ(18O)均值为-8.47‰,δD均值为-70.10‰。指出了该矿区地表水、新生界松散层类第4层含水层(简称"四含水")、煤系砂岩水、太灰水、奥灰水氢氧稳定同位素一般特征。同时根据太灰水和奥灰水氢氧稳定同位素组成,着重分析了底板岩溶水的补给环境与径流环境以及岩溶水与其它含水层之间的联系。     

硼掺杂对SrAl2O4:Eu,Dy长余辉发光材料合成温度及性能的影响

采用固相法合成了系列掺硼SrAl2O4:Eu,Dy长余辉发光材料。通过测试分析合成粉体的物相组成、激发光谱、发射光谱和余辉时间,研究了硼掺杂对SrAl2O4:Eu,Dy长余辉发光材料合成温度与发光性能的影响。实验结果表明,添加硼一方面做为助熔剂可以降低合成温度,另一方面当硼摩尔分数小于30%时,增加硼含量可以延长余辉时间,但硼含量的变化对激发和发射光谱峰值没有明显影响。     

Water isotope variations in the snow pack and summer precipitation at July 1 Glacier, Qilian Mountains in northwest China

This paper presents the stable isotope data of the snow pack and summer precipitation collected at the July 1 Glacier, Qilian Mountains in northwest China and analyses their relationships with meteorologi- cal factors. On an event scale, there is no temperature effect on the δ 18O values in the summer pre- cipitation, whereas the amount effect is shown to be clear. By tracing the moisture transport history and comparing the precipitation with its isotopic composition, it is shown that this amount effect not only reflects the change in moisture trajectory, which is related to the monsoon activities, but is also associated with the cooling degree of vapor in the cloud, the evaporation of falling raindrops and the isotopic exchange between the falling drops and the atmospheric vapor. As very little precipitation occurs in winter, the snow pack profile mainly represents the precipitation in the other three seasons. There are low precipitation δ 18O ratios in summer and high ratios in spring and autumn. The Meteoric Water Line (MLW) for the summer precipitation is δ D = 7.6 δ 18O 13.3, which is similar to that at Delingha, located in the south rim of the Qilian Mountains. The MWL for the snow pack is δ D = 10.4 δ 18O 41.4, showing a large slope and intercept. The deuterium excess (d) of the snow pack is positively correlated with δ 18O, indicating that both d and δ 18O decrease from spring to summer and increase from early autumn to early spring. This then results in the high slope and intercept of the MWL. Sea- sonal fluctuations of d in the snow pack indicate the change of moisture source and trajectory. During spring and autumn, the moisture originates from continental recycling or rapid evaporation over rela- tively warm water bodies like Black, Caspian and Aral Seas when the dry westerly air masses pass over them, hence very high d values in precipitation are formed. During summer, the monsoon is responsi- ble for the low d values. This indicates that the monsoon can reach the western part of the Qilian Mountains.     

3a0．6Sr0．4TiO3／MgO／Mg2SiO4复相陶瓷的制备与介电可调性能

采用标准电子陶瓷工艺，制备了Ba0．6Sr0．4TiO3／MgO／Mg2SiO4复相陶瓷（MgO和Mg2SiO4按相同重量加入），研究了MgO和Mg2SiO4含量对复相陶瓷微观结构、介电性能及介电可调性的影响．结果表明，随着MgO和Mg2SiO4含量的增加，陶瓷的晶粒尺寸略有增大，低频（100kHz）介电常数、介电损耗、介电可调度和介电常数温度系数降低．随着偏置电场的增强，介电常数降低，介电损耗变化不大（均在10^-3量级）．当MaO和Mg2SiO4的百分含量均为30％时，获得了室温介电常数为101．6、介电损耗为0．0017及1．79kV／mm偏置电场下介电可调度为12．19％、介电常数温度系数为0．009℃^-1的介电性能。     

吕梁地区近周营组蚀变火山岩 U-Pb-Hf同位素特征及其地质意义

选择吕梁群中原岔上群北部地层的蚀变火山岩进行锆石U-Pb年代学和Hf同位素研究。锆石U-Pb测试获得两组年龄结果, 较年轻的谐和年龄为1813±6 Ma (n=7), 较老的²⁰⁷Pb/²⁰⁶Pb加权平均年龄为2516±31 Ma(n=2), 前者为火山岩喷发时代, 后者代表捕获锆石年龄。年轻锆石的ε_Hf(t)值为-10.8~-2.3, T_DM1值为2308~2655 Ma; 捕获锆石的ε_Hf(t)值为+10.0~+13.1。年龄约为2.5 Ga锆石的ε_Hf(t)值高于亏损地幔演化线, 考虑到UPb同位素和Hf同位素测点位置不完全相同, 说明所获得的Hf同位素组成为无地质意义的混合数值; 年龄约为1.8 Ga锆石的Hf同位素特征反映其可能源于富集地幔或受地壳物质混染的亏损地幔。结合前人的研究成果, 推断岩浆作用事件发生在约1.81 Ga 的碰撞后阶段。