La1-xCaxMnO3纳米单晶丝的制备及磁热效应研究

采用化学共沉淀法和热处理的方法制备了La1-xCaxMnO3(x=0.3,0.4,0.5)系钙钛矿型氧化物(LCMO),经XRD确定样品为钙钛矿型结构.TEM分析表明样品直径约为40nm的枝节状纳米丝,用△Tad-T测量仪测量了△Tad-T.与块状样品相比居里温度的波峰变宽,绝热磁温变降低.     

Gd4(BixSb1-x)3系列合金在低磁场下的磁热效应

用高频悬浮炉熔炼了Gd4(BixSb1-x)3系列合金,利用X光粉末衍射技术确定其结构。在1.3T的磁场下,利用自制的△Tad-T曲线测量仪直接测量了该系列合金的磁热效应。发现Gd4(BixSb1-x)3系列合金在低磁场下具有较大的磁热效应,通过改变Bi的含量,其居里温度在267K～332K温度之间增加,从而在一个较宽的温度范围内能获得较大的绝热温变。在对退火前后的样品进行△Tad-T测量后,发现其热稳定性很好。实验结果说明Gd4(BixSb1-x)3系列合金是一种性能良好的磁致冷材料。     

水热合成La0.65Ca0.18Sr0.17MnO3及其磁热效应的研究

采用水热合成法制备了正交晶系钙钛矿型La0.65Ca0.18Sr0.17MnO3粉末样品,样品为棱长2μm～8μm的立方体.在1.4T的磁场下,最大绝热磁温变(△Tad)为0.14℃,绝热温变跨度较大,居里温度Tc为297K.     

水热合成La0.7Ca0.3-xBaxMnO3化合物及其磁热性能的研究

采用水热合成法制取了钙钛矿La0.7Ca0.3-xBaxMnO3化合物.通过扫描电镜(SEM)观测与X射线衍射仪(XRD)测量,发现La0.7Ca0.3-xBaxMnO3中Ba离子的掺杂对其形貌有一定影响,但对其晶体结构没有影响.在1.4T的磁场下,利用自制的△Tad-T曲线测量仪测得其磁热效应,发现Ba离子的掺杂量x与磁热效应△Tad之间没有明显规律,但与居里温度Tc之间有一定规律性.利用最小二乘法回归Tc与x的拟合曲线,对实验起到理论指导作用.     

Pechini法制备类钙矿型复合氧化物La_(2-x)Sr_xCuO_4及性能表征

采用Pechini法合成了类钙钛矿型复合氧化物La2-xSrxCuO4(x=0~0.4)。运用XRD、TG、SEM、BET及H2-TPR对样品进行了表征。考察了柠檬酸用量、焙烧温度以及锶的掺杂量等对产物物相、比表面积及催化性能的影响。结果表明,当柠檬酸与金属离子的摩尔比为4∶1、焙烧温度为800℃时所合成的样品为结晶性好、粒度分布均匀、具有单一物相的类钙钛矿型La2-xSrxCuO4(x=0~0.4)。XRD图谱表明,当x0时,所有合成样品均为具有单一晶相的类钙钛矿型复合氧化物。随着掺锶量的增加,样品比表面积增加,其低温氧化性能也随之提高。     

钙钛矿结构氧化物La_(0.5)Sr_(0.5)CoO_3的电导性能研究

采用固相反应法制备了La_(0.5)Sr_(0.5)CoO_3样品,利用X射线衍射仪和拉曼光谱仪对样品结构进行分析。XRD结果显示,La_(0.5)Sr_(0.5)CoO_3样品为单相的立方钙钛矿结构。拉曼光谱图中可看到由氧八面体旋转产生的谱峰以及由Co—O键角及键长振动形成的二级拉曼峰。利用第一性原理的方法计算了La_(0.5)Sr_(0.5)CoO_3的能带、态密度与分波态密度,结果表明Sr~(2+)的掺入可以使不导电的钙钛矿型氧化物LaCoO_3的导电性发生改变,这对钙钛矿型氧化物LaCoO_3的电导特性研究具有指导意义。     

钙钛矿型复合氧化物Nd1-xSrxFeO3-δ的电输运性能

用固相反应法合成了钙钛矿型复合氧化物Nd1-xSrxFeO3-δ(x=0.2,0.4,0.6,0.8)样品,对各样品作了结构分析,对x=0.4样品作了热重分析,测试了各样品在不同温度下的直流电导率,给出了活化能,分析了材料的电输运机理.结果表明,所有样品都呈类钙钛矿结构,在低温段,载流子具有p型小极化子导电特征.对于这种电输运特性,结合材料的失氧规律,给出了合理的解释.     

钙钛矿氧化物Eu_(1-x)Sr_xCoO_(3-δ)的结构和性能

以固相反应法合成了钙钛矿型复合氧化物Eu_(1-x)Sr_xCoO_(3-δ)(x=0.1,0.3,0.5,0.7)材料。研究了各样品的晶体结构、化学状态和电输运性能,测试了样品在不同温度下的直流电导率。结果表明,合成样品都呈类钙钛矿结构,在低温段,载流子具有p型小极化子导电特征,同时,样品随着掺杂比例的变化晶格氧变化较大,Eu0.5Sr0.5CoO3-δ氧空位浓度最大,氧输运性能较好,是较好的固体氧化物燃料电池阴极材料。     

热压烧结制备Li3/8Sr7/16Ta3/4Hf1/4O3钙钛矿型固体电解质

采用热压烧结制备了Li_3/8Sr_7/16Ta_3/4Hf_1/4O₃钙钛矿型固体电解质, 研究了不同烧结方式对样品性能的影响。通过X射线衍射仪表征材料的晶体结构, 扫描电子显微镜观察组织形貌, 交流阻抗仪测试电化学性能。结果表明:样品为立方KTaO₃相, 热压烧结成功合成了钙钛矿结构固体电解质, 相对于常压烧结, 热压烧结制备的样品孔隙更少, 晶粒之间结合更加紧密, 致密度高达94.0%, 离子电导率为4.33×10-4S·cm(T=298K).      

溶胶-凝胶法制备的(La1-xCex)2/3Sr1/3MnO3超微粉末微波吸收特性研究

采用溶胶-凝胶法制备了钙钛矿型锰氧化物(La1-x Cex)2/3Sr1/3 MnO3(x=0.1,0.3,0.5)超微粉末,用XRD分析了该材料的相结构,并用AV3618型微波矢量网络分析仪测试了样品在8.2GHz～12.5GHz范围内的微波吸收特性.结果表明,样品在1000℃焙烧后出现单一的钙钛矿型结构,当材料涂层厚度为1mm、x=0.3时,(La1-x Cex)2/3 Sr1/3 MnO3的吸波性能最佳.在测试频段内有三个吸收峰,最高的吸收峰在9.1GHz处,峰值高达36.8dB,并且吸收衰减量大于18dB的频带宽度达2.2GHz.     

China's Major Non-ferrous Metals Imports & Exports

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Zinc Production by Province in 2014

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80% of Chinese Firms Purchasing Overseas Mines Ended up in the Red

<正>Minmetals Resources acquired the world’s largest copper mine under construction for USD5.85 billion.One after another,listed companies Jien Nickle,China Molybdenum and Chihong Zinc and Germanium raised money to get involved in overseas mining projects…SOEs and private enterprises are engaged in a frenzy of overseas mine purchasing.A reporter with Economic     

Copper Processing Profit Dropped Sharply,Copper Consumption Will Face Impact in the Second Half of the Year

正Judging from China’s copper consumption field,the biggest consumption unit is electric power,which accounts for 47%of total consumption;it is followed by light industry sector,including household electrical appliance,machinery,durable goods and hardware etc,which accounts for 22%of total consumption;followed by transportation field,     

Central Geological Prospecting Fund Newly Added 16.47 Million Tonnes of Bauxite in 2013

正In 2013,the Central Geological Prospecting Fund(CGPF)Project newly discovered 15 ore fields,including 3 large above ore fields,and 5medium sized ore fields.The reporter learned from the recently published"Annual Report of Central Geological Prospecting Fund Project(2013)"that,from 2006 to 2013 the CGPF     

Manufacturers of Copper Tube for Central Air Conditioner Use Face Mounting Pressure in the Final Quarter of the Year

正This year,the investment growth rate of real estate industry continued to slow down,sold area of commercial housing also dropped significantly,which brought huge pressure to the domestic air conditioning manufactures.In the first half of the year,by relying on high growth in national financial expenditure,along with investment in public infrastructure     

Xinjiang Ranks No.1 in Production of Primary Aluminum in China

正Kang Yi,Honorary Chairman of China Nonferrous Metals Industry Association,said recently at the Forum on Development of the Non-ferrous Metals Industry in Central and Western China held in Zhengzhou that,as more and more electrolytic aluminum factories in Xinjiang came into operation,the electrolytic aluminum output of Xinjiang had reached2,275,000 tons in the first 7 months this year,     

Shenhuo Coal Industry and Electricity Power Completed800,000 t/a Aluminum Project in Xinjiang

正"Xinjiang project has been completed according to schedule,but total completion and total start of production are two different concepts,after completion it still needs a gradual process of reaching production target."On the morning of November 3,Shenhuo Coal Industry and Electricity Power told investors the above statement on the investor interaction platform.     

Guangdong Metal Transaction Center has Become the Second Largest Precious Metal Transaction Platform Nationwide

正The reporter learned from Guangdong Province Precious Metal Transaction Center that in 2013the Center maintained healthy development momentum,and had become the second largest precious metal transaction platform in China in terms of market size;currently Guangdong is quickening steps of financial innovation for the Center,aiming to build a transaction center with international core competitiveness.     

Seven Rare Earth Projects Involving Close to 3 Billion Yuan Investment Landed In the HighTech Zone

正On May 22,Baotou Rare Earth Industry Cooperation Consultation MeetingProject Agreement-signing Ceremony was held in Ningbo,nearly 40 enterprises from Ningbo,Guangdong,Hunan,and Shanxi participated in project consultation.After multi-lateral communication,agreements were signed for a total of 7 rare earth projects successfully.