电子辐照BaF2晶体的正电子寿命谱研究

用不同能量和注量的电子辐照BaF2∶Sr晶体,分别测量了辐照前后的正电子寿命谱和吸收谱。为了与正电子寿命谱结果对比,也测量了相应的荧光谱。结果表明,在能量为1.5MeV和1.8MeV,注量为1.25×1015到2.57×1016e-cm-2mai的电子辐照情况下,在BaF2∶Sr晶体中主要产生F-H对,F色心和其它一些由杂质引起的色心;辐照温度对这些色心的形成和演化过程有较大的影响。     

纳米La0．6Sr0．4MnO3／Fe粉复合体系微波吸收性能

用溶胶-凝胶法制备了La0.6Sr0．4MnO3粉体,与纳米Fe粉按不同质量比复合,得到复合材料样品。测试了样品在2～18GHz微波频率范围内的复介电常数、复磁导率,计算了微波反射系数和损耗角正切,初步探讨了材料的微波吸收机制。结果表明,当复合质量比为6：4、样品厚度为2mm时,大于10dB的吸收带宽为3．4GHz,最大吸收峰值为16dB,微波损耗是介电损耗和磁损耗共同作用的结果。     

Variations in CaCO3 content and Sr isotopic composition of loess and records of paleoclimatic fluctuations

The carbonate Sr isotopic composition of the Heimugou loess-paleosol section in Luochuan of Shaanxi Province shows large variation, with the 87 Sr/86 Sr ratios ranging from 0.7104 to 0.7120. The carbonate in paleosol has in general higher 87Sr/86Sr than the carbonate in loess. In the loess-paleosol section, the Sr isotopic composition vary with an about 100 ka periodicity, corresponding to the change of global glacial cycle and comparable with the variation of Sr isotopic composition of paleosea water. This result indicates that the Sr isotopic composition of carbonate in loess can be an indicator of crustal weathering and paleoclimate change. The fluctuation in Sr isotopic composition of paleoseawater is mainly controlled by the continental riverine flux of Sr and its isotopic composition.     

Pb, Sr isotopes in organic matter of Lower Tertiary hydrocarbon source rocks in Liaohe Fault Depression

The Pb, Sr isotopic compositions in organic matters (kerogen and soluble organic matter) of Lower Tertiary hydrocarbon source rock in Liaohe Fault Depression is first reported. There is a great variable rang of Pb isotopic compositions in kerogen, 206Pb/204Pb = 17.488-18.656, 207Pb/204Pb= 15.388-15.692, 208Pb/204Pb = 37.656-37.484. And soluble organic matters have a very stable Pb isotopic composition, that is 206Pb/204Pb = 17.424-17.601, 207pb/204pb= 15.376-15.448, 208Pb/204Pb = 37.620-37.870. Sr isotopic composition varies in the range of 0.747 59-0.716 79 in kerogen and of 0.709 67-0.747 59 in soluble organic matters that have a great range. It is shown that mantle fluid can influence organic matters and make them form hydrothermal hydrocarbon in the geoglogic environment of rift basin.     

地理信息系统在矿产预测中的应用——以华蓥山锶矿带为例

地理信息系统（ＧＩＳ） 是近年来发展起来的综合处理和分析空间数据的一种十分有效的技术。本文以华蓥山锶矿带为例, 介绍了运用ＧＩＳ技术进行矿产预测的方法。     

Preparation and luminescence characteristics of Sr_3SiO_5:Eu~(2 ) phosphor for white LED

The Sr3SiO5:Eu2 phosphor was synthesized by high temperature solid-state reaction. The emission spectrum of Sr3SiO5:Eu2 shows two bands centered at 487 and 575 nm, which well agree with the theoretic values of emission spectrum. The excitation spectrum for 575 nm emission center has several excitation bands at 365, 418, 458 and 473 nm. And the results show that the emission spectrum of Sr3SiO5:Eu2 is influenced by the Eu2 concentration. The relative emission spectra of the white-emitting InGaN-based YAG:Ce3 LED and Sr3SiO5:Eu2 LED were investigated. The results show that the color development of InGaN-based Sr3SiO5:Eu2 is better than that of InGaN-based YAG:Ce3 , and the CIE chromaticity of InGaN-based Sr3SiO5:Eu2 is (x=0.348, y=0.326).     

花状Sr3Al2O6：Eu^2＋晶体的干燥方式与发光性能

为研究稀土发光纳米晶的微观结构和形貌对发光性能的影响,用凝胶-微波干燥法和凝胶-烘箱干燥法制备了花状形貌的Sr3Al2O6晶体．研究了微波干燥和烘箱干燥两种不同的干燥方式对溶胶-凝胶法制备的Sr3Al2O6：Eu^2＋发光粉体粒径、形貌、团聚程度、干燥时间及发光性能等的影响,结果表明采用微波干燥不仅可以大大缩短干燥所需时间,而且有利于减弱Sr3Al2O6：Eu^2＋发光粉料的团聚和团聚程度,制得了颗粒分散均匀、团聚程度低、发光强度高的Sr3Al2O6：Eu^2＋花状形貌粉体．研究了Sr3Al2O6：Eu^2＋发光粉体的新型形貌对发光性能的影响,微波干燥法制备的均匀分散的花状形貌发光粉体发光强度高,余辉时间长达20min．     

The possible contribution of a mantle-derived fluid to the Ningwu porphyry iron deposits-Evidence from carbon and strontium isotopes of apatites

Apatite is a characteristic mineral for the iron deposits in the Ningwu region. Apatite shows a range of δ^13CPDB values from -9.6‰ to -0.6‰, and most of them with the δ^13CPDB values distributed in a range of mantle carbon （i.e., -2‰to -9‰）, except for samples T-06-1 and J-06-3. Apatites in the Ningwu porphyry iron deposits yield a narrow variation range of ^87Sr/^86Sr values from 0.706326 to 0.707577, similar to those of the volcanic and subvolcanic rocks and higher than that of a typical mantle-derived magmatic apatite （i.e., about 0.7040）, indicating that formation of the apatites was involved with crust material contamination.δ^13CPDBand ^87Sr/^86Sr values of the apatite indicate a possible contribution of mantle-derived fluid and material to formation of the Ningwu porphyry iron deposits, supported by regional geology, regional gravities and geochemistry of the volcanic and subvolcanic rocks in the Ningwu region.     

挤压态Mg-9Li-3Al-xSr镁合金的微观组织与力学性能

采用SEM、EDS、XRD、TEM和力学性能测试等手段研究了挤压态Mg-9Li-3Al-xSr(LA93-xSr,x=0,1.5,2.5,3.5wt%)镁合金的微观组织与力学性能,探讨了Sr含量对挤压态合金的微观组织及力学性能的影响规律。结果表明:LA93-xSr镁合金包括α-Mg(hcp)和β-Li(bcc)两种基体相。Sr含量对挤压态合金的晶粒大小没有明显影响。随着Sr元素的加入,合金中形成Al4Sr新相,主要分布于α/β相界面,并沿挤压轴向呈流线分布。合金的强度随着Sr含量的增加呈现先增加后降低的趋势,合金的延伸率随着Sr含量的增加呈现逐渐降低的趋势。当Sr含量为2.5wt%时,挤压态Mg-9Li-3Al-2.5Sr(LAJ932)合金的抗拉强度达到最大值235.2MPa,屈服强度达到220.6MPa,延伸率为19.4%,合金呈现出良好的力学性能。挤压过程中,α-Mg相中发生形变诱发的晶粒细化,β-Li相中发生常规动态再结晶。