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Regulation mechanism of EM parameters in natural ferrite and its application in microwave absorbing materials

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Science china(Technological Sciences) 2006年第1期49卷 38-49页

作者： ZHENG Yongchun1,2, wang shijie2, FENG Junming2, li {3.1, OUYANG Ziyuan1,2, liu jianzhong1 & li Xiaobiao2 1. National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, china 2. State Key Laboratory of Environmental geochemistry, Institute of geochemistry, Chinese Academy of Sciences, guiyang 550002, china 1. National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China 2. State Key Laboratory of Environmental geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang 550002 China

Electromagnetic (EM) parameters (ε ′, ε ″, μ ′, μ″ ) of several M2+Fe2O4 and Fe2O3.type natural ferrites with different geological occurrences are measured in this pa-per. The measurement results show that EM parameters of a magmatic-occurring natural ferrite is very different from other types occurring from sedimentary-metamorphic iron deposit, hydrothermal vein iron deposit, outer contact of magmatic iron deposit. It has potential to be used as magnetic absorbent in microwave absorbing materials. After min-eral separation and concentration, this magmatic-occurring natural ferrite was processed into type A ferrite absorbent. Type A natural ferrite absorbent is a kind of magnetic material with low dielectric constants, high magnetic conductivity and high EM loss. Its EM pa-rameters are ε ′ = 58.60, ε ″ = 10.0, μ ′ = 1.2-1.5, μ ″ = 1.0-1.2, respectively. In order to illuminate the regulation mechanism of EM parameters, we studied the chemical and mineral composition of type A ferrite absorbent. There is high concentration of natural impurities, which regulate the EM parameters of type A ferrite greatly. For comparison, the other types of natural ferrite, single-phase magnetite and two-phase iron minerals (ilmen-ite and magnetite), have few impurity. Thus regulation mechanism of EM parameters was absent in these ferrites. As a result, the regulation of EM parameters is advantageous to develop type A natural ferrite as excellent absorbent, lowers the reflectivity coefficients and enhances the absorbing efficiency of MAM made from it. Furthermore, the impurities in type A natural ferrite and its effects on EM parameters are very difficult to simulate in the synthesize ferrite. The carbonyl-iron powder is another kind of absorbent that is used ex-tensively in MAM. To compare the absorbing properties of these two absorbent, type A natural ferrite and carbonyl-iron powder were mixed with rubber and processed into mi-crowave absorbing sheets with the same procedures and tec

关键词： natural impure ferrite, complex permittivity, complex permeability, microwave absorbing materials.

Primary scientific results of Chang'E-1 lunar mission

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Science china Earth Sciences 2010年第11期53卷 1565-1581页

The strategic plan for the development of the unmanned Chinese Lunar Exploration Program is characterized by three distinct stages: "orbiting around", "landing on" and "returning from" the Moon. The first Chinese lunar probe, Chang'E-1, which was successfully launched on October 24th, 2007 at Xichang Satellite Launch Center, and guided to crash on the Moon on March 1st, 2009, at 52.3.°E, 1.50°S, in the north of Mare Fecunditatis, is the first step towards the "orbiting around" stage. The Chang'E-1 mission lasted 495 days, exceeding the expected life-span by about four months. A total of 1.3. TB raw data was received from Chang'E-1. It was then processed into 4 TB scientific data products at various levels. Many scientific results have been obtained by analyzing these data, including especially the "global lunar image from the first Chinese lunar explora- tion mission". All scientific goals of Chang'E-1 have been achieved. It provides much useful materials for further advances of lunar sciences and planetary chemistry. Meanwhile, these results will serve as a firm basis for future Chinese lunar missions.

关键词： lunar orbiter Chang’E-1 scientific data results

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1961-2017年贵州降水时空变化特征

水土保持研究 2019年第6期26卷 145-150页

作者：李勇刘秀明王世杰曹乐张志才中国科学院大学北京100049 中国科学院地球化学研究所环境地球化学国家重点实验室贵阳550081 中国科学院普定喀斯特生态系统观测研究站贵州普定562100 河海大学水文水资源与水利工程科学国家重点实验室南京210098

为研究贵州地区降水的时空演变规律,根据贵州省84个气象站1961—2017年的降水量资料,利用EOF和REOF方法、Mann-Kendall检验、Cramer法、YAMAMOTO法和滑动t检验及Morlet小波分析法,对贵州地区57年来降水的空间分布、时间系数变化特征和... 详细信息

为研究贵州地区降水的时空演变规律,根据贵州省84个气象站1961—2017年的降水量资料,利用EOF和REOF方法、Mann-Kendall检验、Cramer法、YAMAMOTO法和滑动t检验及Morlet小波分析法,对贵州地区57年来降水的空间分布、时间系数变化特征和时间序列的趋势性、突变性及周期性进行了分析。结果表明:EOF方法可以很好地解释降水场的时空分布特征,前2个特征向量累计贡献率达50.08%,揭示了两种典型的分布场,即全局型和东西反向型。分析特征向量所对应的时间系数,贵州省的降水场主要表现为全省多雨、全省少雨、东多西少、东少西多4种类型,REOF可将贵州降水场分为东西部两个区域,通过Mann-Kendall检验发现均存在降水减少的突变,并通过Cramer法、YAMAMOTO法和滑动t检验对结果进行验证,发现Ⅱ区比Ⅰ区降水突变明显。Morlet小波分析表明,贵州地区降水存在着显著的28 a周期变化。

关键词：降水 EOF分析法时空分异

热带地区碳酸盐岩上覆红色风化壳的成因机理及元素演化

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中国地质 2021年第2期48卷 651-660页

作者：张连凯季宏兵刘秀明魏晓罗刚王世杰 NGUYEN Dại Trung NGUYEN Quoc Dinh 中国地质调查局昆明自然资源综合调查中心云南昆明650100 中国地质科学院岩溶地质研究所/自然资源部广西岩溶动力学重点实验室广西桂林541004 中国科学院地球化学研究所/环境地球化学国家重点实验室贵州贵阳550081 北京科技大学土木与环境工程学院北京541004 贵州大学农业学院贵州贵阳550025 贵州省黔东南苗族侗族自治州镇远县都坪镇政府贵州黔东南苗族侗族自治州贵州镇远522625 越南地质与矿产资源研究所河内100000

开展热带岩溶地区红色风化壳元素地球化学演化规律研究,有助于丰富碳酸盐岩风化成土理论的认识。在越南北部选取典型的碳酸盐岩风化剖面,分析热带气候条件下碳酸盐岩上覆红色风化壳中主量元素的物质来源和演化特征。结果表明:无论Ti/Zr... 详细信息

开展热带岩溶地区红色风化壳元素地球化学演化规律研究,有助于丰富碳酸盐岩风化成土理论的认识。在越南北部选取典型的碳酸盐岩风化剖面,分析热带气候条件下碳酸盐岩上覆红色风化壳中主量元素的物质来源和演化特征。结果表明:无论Ti/Zr的元素比值分析,Hf-Zr、Nb-Ta及Sm-Nd的元素对协变分析,还是上地壳元素平均值(UCC)标准化分析,两个剖面的上覆风化壳均显示原地残积的特征,即两个剖面是碳酸盐岩的原位风化产物。碳酸盐岩风化成土过程中,CaO、MgO淋失明显,Al_2O_3.Fe_2O_3.生富集,显示两个剖面均经历较强的风化过程,但是白云岩和灰岩剖面有一定的分异特征。越南北部白云岩风化剖面从基岩到上部土层显示出稳定的Ti-Fe元素共富集特征,而灰岩剖面中Fe的增长速率明显超过Ti。白云岩上覆风化壳经历了强烈的风化作用,其脱硅作用弱于灰岩风化剖面,而富集铝的作用强于灰岩。迁移系数的演化规律说明两个剖面中长石成分(钾长石、钠长石等)或次生矿物(伊利石等)在风化成土过程中逐渐分解,同时Al、Fe、Si等稳定元素的在风化剖面中不断富集。

关键词：碳酸盐岩红色风化壳主量元素演化特征地质调查工程越南