Structure and Transport Properties of La0.67Ca0.33Mn1-xAlxO3

The effects of Al ion doping on the Mn site were studied for the colossal magnetoresistance material La0.67Ca0.33MnO3. It is found that the volume of the crystal cell decreases monotonically when the population of Al3 increases across the entire doping range. As the Al3 population increases, the resistance of the material rises rapidly, while the insulator-metal transition temperature TIM decreases linearly. At small Al3 dosage, a thermal activation model properly describes the transport properties at T>TIM, while a metallic model is more suitable at T相似文献   

工艺条件对电沉积CoPtW合金成分的影响

报道了以钨酸钠、硫酸钴和二亚硝酸二胺铂为主盐、以柠檬酸盐为络合剂电沉积钴铂钨合金的工艺过程。研究了镀液中钨盐浓度、络合剂浓度、电流密度、镀液温度等沉积条件对钴铂钨合金成份的影响。结果表明，在实验条件下，镀液中钨盐含量的增加、电流密度的增大和镀液温度的升高都会引起合金镀层中的钨含量增大。络合剂用量的增加使合金镀层中的钨含量下降，而使钴和铂的含量增加。     

Transport Properties of Rare Earth Manganese Oxide Lao.67 Ca0.33Mn1-x FexO3

The transport properties were studied for rare earth manganese oxide La0.67Cao.33Mn1-x FexO3(x=0-O.3) systems. It is found that with increasing Fe^3 -doping content x, the resistance increases and the insulator-metal transition temperature (T1M) shifts to lower temperature. If the doping content is small, the transport properties manifest metallic characteristics in the temperature range of T＜T1M, while they will obey a thermal activation model in the temperature range of T＞T1M. Such a behavior may be attributed to the Fe^3 -doping and possible Mn ions scattering to electrons. The Fe^3 doping may lead to the formation of Fe^3 -O^2- -Mn^4 channels, which could terminate the double exchange Mn^3 -O^2--Mn^4 channels. The antiferromagnetic clusters of Fe ions may induce the Mn ions to scetter to the electrons.     

托卡马克中高能粒子的初始轨道及其损失研究

采用两种模型对高能粒子在托卡马克中的轨道进行了研究,比较两者计算结果,表明定性吻合较好,并分析了定量上差异成因.同时讨论了等离子体有关参数对高能粒子轨道损失的影响,这些结果对展开高能粒子约束的研究是非常有意义的.     

Transport Properties of Rare Earth Manganese Oxide La_(0.67)Ca_(0.33)Mn_(1-x)Fe_xO_3

CompoundsofthetypeLn1-xAxMnO3(Ln =rareearth ,A =Ca ,Ba ,Sr ,etc .)havebeenthepopularsubjectsofextensiveresearchrecently ,mainlyduetotheexistenceofcolossalmagnetoresistance(CMR ) [1～ 3] .Atroomtemperature ,theperovskitecompoundLnMnO3isantiferromagneticinsulatorwhereMnistrivalent .ThepartialsubstitutionoftrivalentLnionswithdivalentionssuchasCa ,Ba ,Sr ,andPbetc .yieldsanewcompoundexhibitingstrongferro magnetismandhighmetallicconductivity .Thetrans portpropertyinthesecompoundscanbepartly…     

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