简介:Themicrostructuresofas-castandas-solutionMg–12Gd–2Er–1Zn–0.6Zralloyswereinvestigatedbyopticalmicroscopy(OM),scanningelectronmicroscopy(SEM),transmissionelectronmicroscopy(TEM),highresolutiontransmissionelectronmicroscopy(HRTEM)X-raydiffraction(XRD)andselected-areaelectrondiffraction(SAED)inthepresentinvestigation.TheresultsshowthattheprimaryeutecticphaseMg5(Gd,Er,Zn)andsomeflocculentfeaturesarefoundintheas-castalloy;theSAEDpatternindicatesthattheseflocculentfeaturesarethedenseareasofstackingfaults.The14H-LPSOstructureprecipitatesinthetemperaturerangeof673–793K,andthevolumefractionof14H-LPSOstructureincreaseswiththeextensionofheatingtime;however,thereisnoprecipitationof14H-LPSOstructurewhenthetemperaturereachesupto803K.Inaddition,theMg5(Gd,Er,Zn)phasedissolvesgraduallyalongwiththeprecipitationof14H-LPSOstructure.
简介:LaCrO_3的nano粉末被一条大音阶的第五音胶化线路准备。从350~550K的LaCrO_3nano粉末的热能力被DSC方法测量并且是表示了:C_(p(LaCrO3))(±0.112)=166.844-8.500x10~(-3)T-1.022x10~6T~(-2)(J/(摩尔·K))(350-550K)。一个EMF测量集会为流电的房间作为电解质与CaF_2被开发。可逆房间的FrommeasuredEMF数据,(-)磅,La_2O_3,LaF_3,|CaF_2|O_2(1atm),LaF_3,LaCrO_3,Cr_2O_3,磅(+),和吉布斯的相关价值释放的O_2(1atm)精力,吉布斯LaCrO_3的形成的免费精力从700~885K被计算:ΔG_(f,LaCrO3)~Θ=-1555.364+0.354T(kJ/mol)(700-885K)。并且免费精力从简单氧化物La_2O_3andCr_2O_3反应改变的吉布斯是打算的是:ΔG_(f,公牛(LaCrO3))~Θ=-94.758+8.530x10~(-2)T(kJ/mol)(700-885K)。
简介:采用先水热合成(150°C,12h)、后煅烧(1000°C)来实现(Y0.95Eu0.05)2O3亚微米球形和微米板片红色荧光颗粒的形貌可控合成。通过XRD、FT-IR、FE-SEM和PL等检测手段对样品进行分析。结果表明:将尿素与Y+Eu的摩尔比由10增大至40~100,得到的前驱体由碱式碳酸盐亚微米球转变为碳酸盐微米片;经1000°C煅烧所得氧化物能够继承前驱体的形貌特征;板片二维形貌的限制内部晶粒自由生长,使更多的(400)晶面暴露在板片颗粒表面;在250nm紫外光的激发下,荧光颗粒的荧光发射峰位及荧光不对称因子[I(5D0→7F2)/I(5D0→7F1),~11]均与颗粒形貌的相关性不强,但荧光强度呈现明显的形貌依存性;微米板片颗粒的尺寸大,从而其比表面积小,因此具有更高的荧光强度(微米板片在~613nm处的荧光强度为球形颗粒的~1.33倍)。
简介:研究LiNi0.5Mn0.5O2电极在LiNO3水溶液中的电化学行为,同时分析该电极在不同pH值电解液中的循环衰减原因。循环伏安测试显示LiNi0.5Mn0.5O2在浓度为5mol/L的LiNO3水溶液中具有较好的锂离子脱嵌能力。对比发现,LiNi0.5Mn0.5O2电极在浓度为5mol/L,pH值为12的LiNO3水溶液中具有最好的循环稳定性能。通过交流阻抗法、X射线衍射分析及电极形貌的对比分析发现:电极在浓度为5mol/L,pH值为12的LiNO3水溶液中循环时,电极的表面形貌和电极结构都能得到较好的保持,电极的电荷传递阻抗得到明显抑制,因此在该pH值电解液中的循环稳定性最好。
简介:TiO2nanoparticleswithdifferentphasesarepreparedbyhydrolysisoftitaniumtetrabutoxideinthepresenceofHCl.ThecompositionandmicrostructureoftheresultingsamplesarestudiedbyXRDandTEM.TheseresultsshowthattherangeofparticlesizeofTiO2isfrom20to30nm.ThemechanismofTiO2photocatalysisreactionhasbeendiscussedextensively.PhotocatalyticactivitiesofnanometerTiO2arealsoevaluatedbydegradationofthecrystalvioletsolution.ExperimentalresultsindicatethatthesynergisticactionofH2O2andultrasonicwavegreatlyenhancesphoto-catalyticreactionofTiO2.
简介:GaxIn1-xAs1-ySbyalloyshavebeengrownbyatmosphericpressureMOCVDonn-GaSb(Te-doped)substrate.Thesohdcompositionwasdeterminedbyusingelectronmicroprobe.ThealloysofGalnAsSbwithcompositioninmiscibilitygapweresuccessfullygrown.TheopticalpropertiesofGaxIn1-xAs1-ySbylaverswerecharacterizedbythephotoluminescenceandtheinfraredabsorption.Thespectralresponsesofp+-GaInAsSb/p-GaxIn1-xAs1-ySby/n-GaSbdetectorsshowedwavelengthcutoffat2.4μmanddetectivity-D*=5×108cmHz1/2/Watroomtemperature.
简介:Iron(Ⅲ)-dopednanostructureTiO2-coatedSiO2(TiO2/SiO2)particleswerepreparedusingthelayer-by-layeras-semblytechniqueandtheirphotocatalyticpropertywasstudied.TiO2colloidsweresynthesizedemployingthesol-gelmethodwithTiCl4asaprecursor.ThesampleswerecharacterizedbyFouriertransforminfraredspectroscopy(FTIR),SEM,EDS,XPS,andXRD.TheexperimentalresultsshowthatTiO2nanopowdersonthesurfaceofSiO2particlesarewelldistributed,theamountofTiO2isincreasedwiththeaddingofcoatinglayers,thepureanatase-TiO2coatinglayersaresynthesizedat500°C,andthephotocatalyticactivityofFe3+-dopedTiO2/SiO2ishigherthanthatofundopedTiO2/SiO2.
简介:在80%Al-20%CuO(质量分数)体系中,通过原位反应法制备Al2O3p-Al复合材料。采用不同方法研究CuO颗粒粒度对复合材料合成温度和显微组织的影响。结果表明,CuO颗粒粒度对Al-CuO体系的完全反应温度有显著影响:含有粒度小于6μmCuO颗粒样品的完全反应温度比含有粒度小于100μmCuO颗粒样品的完全反应温度低200°C。当反应温度低于某一临界值时,原位Al2O3颗粒和Al基体之间不能完全结合;当温度高于某一临界值时,原位Al2O3颗粒的形貌从棒状转变成近球形。这两个临界温度受CuO颗粒粒度的影响:含有粒度小于6μmCuO颗粒样品的临界温度比含有小于100μmCuO颗粒样品的临界温度低100℃。
简介:Nb-24Ti-18Si-2Al-2Hf-4CrandNb-24Ti-18Si-2Al-2Hf-8Cralloyswerepreparedbyarcmeltinginawater-cooledcrucibleunderargonatmosphere.Microstructuralcharacteristicsandoxidationresistanceofthealloysat1250℃wereinvestigated.Theresultsshowthat,whentheCrcontentis4at%,themicrostructuresconsistof(Nb,Ti)_(ss)andNb_5Si_3;asCrcontentincreasesto8at%,C14LavesphaseCr_2Nbisformed.Theisothermaloxidationtestsshowthattheoxidationkineticsofthetwoalloysfollowsimilarfeatures.Theweightgainsofthetwoalloysafteroxidationat1250℃for100hare235.61and198.50mg·cm~(-2),respectively.Duringoxidation,SiO_2,TiO_2,Nb_2O_5andCrNbO_4areformedatfirst.Then,Ti_2Nb_(10)O_(29)isformedafteroxidationfor20minandbeginstochangeintoTiNb_2O_7astheoxidationproceeds.SiO_2isformedassolidstateatfirstbutlaterevolvesintoglassystatetoimprovethecohesionofthescale.Afteroxidationfor100h,oxidationproductsconsistofSiO_2,TiNb_2O_7,Nb_2O_5andCrNbO_4.
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简介:研究保温时间对0.98(K0.5Na0.5)NbO3-0.02LaFeO3(缩写为0.98KNN-0.02LF)无铅陶瓷相结构、显微组织、介电性能及铁电性能的影响。所有烧结样品均为纯的伪立方钙钛矿相,保温时间对相结构影响不大。随着保温时间的延长,样品的XRD衍射峰逐渐增强,并且向低角度移动。SEM观察结果显示,随着保温时间的延长,陶瓷样品的致密性提高,晶粒异常长大并出现孪晶结构。介电温谱表明,随着保温时间的延长,介电性能有所降低。电滞回线结果表明,2Pr随着保温时间的延长而增大的程度有所减小,而2E略有增加。在1150℃烧结2h得的到陶瓷的性能较优:εr=2253,tanδ〈5%,2Pr=34.51μC/cm2,2Ec=5.07kV/mm。