简介:通过溶胶凝胶-熔盐法以NaCl为熔盐制备了掺杂Co^2+的Cd1-xCoxFe2O4(x=0~0.5)尖晶石型铁氧体。利用XRD、SEM和VSM等手段对样品进行了结构、形貌和磁性表征,并详细讨论了Co^2+对Co1-xCdxFe2O4(x=0-0.5)铁氧体结构和磁性的影响。结果表明:在研究范围内掺杂后仍然能得到单相尖晶石结构铁氧体;样品均为正八面体;比饱和磁化强度随x的增大而增加。
简介:FenanowirearraywithstrongshapeanisotropywasemployedasthesoftphaseinNd-Fe-Bbasednanocomposites.TheeffectsoftheFenanowiredistributiononmagneticpropertiesofthenanocompositeswereinvestigatedbymicromagneticsimulation.TheresultsindicatethattheshapeanisotropyofFewiresaddedinthesamedirectionastheuniaxialmagnetocrystallineanisotropyofthehardphasecannotincreasethecoercivityofthenanocomposite.Whenthenanowiresaredistributedperpendiculartotheeasyaxisofthehardphase,theshapeanisotropyofsoftphasecanretardthemomentsfromrotatingtothefullreverseddirection,leadingtoenhancedcoercivity.Inaddition,withincreasingthenanowirediameter,thecoercivityofthenanocompositedecreases,butthedipolarinteractionshowsdifferentrolesinmagneticreversalofnanocompositefordifferentdistributionsofnanowires.ThecurrentresultssuggestthatthecoercivityoftheNd2Fe14B/α-Fenanocompositecanbeenhancedbyintroducingthesoftmagneticnanowirearraywiththediameterlessthantheexchangelengthandwiththelongaxisalongthedirectionotherthantheeasyaxisofhardphase.
简介:Inthepresentpaper,twomodelsbasedonartificialneuralnetworksandgeneticprogrammingforpredictingsplittensilestrengthandpercentageofwaterabsorptionofconcretescontainingZrO2nanoparticleshavebeendevelopedatdifferentagesofcuring.Forbuildingthesemodels,trainingandtestingusingexperimentalresultsfor144specimensproducedwith16differentmixtureproportionswereconducted.Thedatausedinthemultilayerfeedforwardneuralnetworksmodelsandinputvariablesofgeneticprogrammingmodelswerearrangedinaformatofeightinputparametersthatcoverthecementcontent,nanoparticlecontent,aggregatetype,watercontent,theamountofsuperplasticizer,thetypeofcuringmedium,ageofcuringandnumberoftestingtry.Accordingtotheseinputparameters,intheneuralnetworksandgeneticprogrammingmodels,thesplittensilestrengthandpercentageofwaterabsorptionvaluesofconcretescontainingZrO2nanoparticleswerepredicted.ThetrainingandtestingresultsintheneuralnetworkandgeneticprogrammingmodelshaveshownthattwomodelshavestrongpotentialforpredictingthesplittensilestrengthandpercentageofwaterabsorptionvaluesofconcretescontainingZrO2nanoparticles.Ithasbeenfoundthatneuralnetwork(NN)andgeneexpressionprogramming(GEP)modelswillbevalidwithintherangesofvariables.Inneuralnetworksmodel,asthetrainingandtestingendedwhenminimumerrornormofnetworkgained,thebestresultswereobtainedandingeneticprogrammingmodel,when4geneswereselectedtoconstructthemodel,thebestresultswereacquired.Althoughneuralnetworkhavepredictedbetterresults,geneticprogrammingisabletopredictreasonablevalueswithasimplermethodratherthanneuralnetwork.
简介:Theeffectofthehot-chargingtreatmentontheperformanceofAB2andAB5hydrogenstoragealloyelectrodeswasinvestigated.Theresultshowedthatthetreatmentcanmarkedlyimprovethevoltageplateauratio(VPR),thehighratedischargeability(HRDA),thediffusioncoefficientofhydrogenDHandthedischargecapacityoftheAB2hydrogenstoragealloyelectrode.TheSEManalysisshowedthatthehot-chargingtreatmentbringsaboutaNi-richsurfaceduetothedissolutionofZroxides.ItisalsoveryhelpfulfortheimprovementofthekineticpropertiesofAB2hydrogenstoragealloyelectrodebecausethemicrocrackingo.fthesurfaceresultsinfreshsurface.ThiscanbethebasicmodificationtreatmentforNiMHbatteryusedinelectricvehicles(EVs)inthefuture.ButforAB5typealloys,thetreatmenthasthedisadvantageofimpairingthecomprehensiveelectrochemicalproperties,becausethesurfaceofthealloymaybecorrodedduringthetreatment.Themechanismofthesurfacemodificationoftheelectrodeisalsoproposed.
简介:以Pickering乳液液滴为模板,通过液滴表面水合作用制备出MgO/Mg(OH)_2复合空心球壳,通过SEM、XRD等手段进行表征,讨论了空心球壳形成机理,并研究了MgO/Mg(OH)_2复合空心球壳对阿维菌素微胶囊的缓释作用,结果表明,MgO/Mg(OH)_2复合空心球壳形貌完整,粒径分布均匀,平均粒径为62μm。水合过程中部分MgO转变成Mg(OH)_2,并优先复合在未反应的MgO粒子上,形成MgO/Mg(OH)_2复合空心球壳。以MgO/Mg(OH)_2复合空心球壳为壁材的阿维菌素微胶囊具有良好的缓释性能。
简介:以硬脂酸锌为Zn源、硫化钠为S源,首次采用油水界面法制备出单分散于环己烷和甲苯的ZnS纳米材料,探索有机溶剂、锌源和油酸浓度等对紫外吸收影响的同时,以ZnS为基质,掺杂Mn^2+和Eu^3+制得ZnS:Mn^2+,Eu^3+发光纳米材料,采用高分辨率透射电子显微镜(HRTEM)、X射线粉末衍射仪(XRD)、紫外可见(UV-VIS)和荧光分光光度计(PL)对产物进行了表征,紫外和HRTEM测试结果均表明,产物为单分散性,平均粒径为4.3nn;荧光测试表明,产物所发荧光较强,肉眼可观测到明显的橙黄色(585nm)和橙红色(616nm)发光;XRD结果显示,产物结构为立方闪锌矿结构
简介:利用水热法制备了不同Ni含量的ZnO(Zn1-xNixO)稀磁半导体材料,通过XRD、FESEM和VSM对产物的结构、形貌及磁性进行了分析与测试,探讨了反应时间对Zn1-xNixO材料结构及磁性的影响。结果表明,反应时间显著影响Zn1-xNixO的结构与磁性,随着反应时间的延长,样品的结晶质量下降,形貌由六方棒状结构转变为片状结构,同时磁性减弱。
简介:刚化学方法在水性和无水介质中合成聚(2-氯苯胺)(P2ClAn)、聚呋喃(PFu)传导性均聚物及复合物并研究丁艇性能。聚合物及其复合物的特征通过了红外光谱、紫外一可见光吸收光谱、热重分析、示差扫描址热法、扫描电镜、磁化率、电导牢测试。研究发现PFu/P2ClAn复合物的热稳定性比P2ClAn/PFu复合物和各自均聚物的要好。按照Gouy等级测试的方法,均聚物及其复合物的传导性机理本质上是极化子和双极化子。研究发现复合物电导率和磁化率值的大小受其客体聚合物含量的影响。P2CLAn/PFu(ω(PFu)=55.8%)电导率为3.21×10^-3S/CM,比各自聚合物的要高(σPFu=1.44×10^-5/CM,σP2CIAn=1.32×10^-5S/CM)。改变复合物合成顺序可以改变电导率、形态特征和热性能。