亚锰酸盐La0.7-xCexCa0.3MnO3的磁电阻效应

用固相反应法制备亚锰酸盐La0.7-xCexCa0.3MnO3系列多晶样品(量分数x＝0，0．05，0．10，0．15，0．20)，并在零磁场和0．3T磁场下研究了电阻和磁电阻与温度(77-300K)的关系．结果发现：随x的增加，样品的巨磁电阻效应减弱，磁电阻峰有所扩宽，磁电阻峰值出现的温度比无掺杂相对提高了约14K．     

退火温度对La0．7Sr0.3MnO3薄膜取向的影响

在LaAlO3(100)单晶上,通过化学溶液法(CSD)制备了有取向性的La0.7Sr0.3MnO3薄膜,对不同退火温度下薄膜的取向性进行了研究.结果表明:随着温度的升高,薄膜的取向性变好.     

La0.7Ca0.3MnO3与Al复合体系电磁输运性质的研究

研究了具有庞磁电阻（CMR）效应的锰基钙钛矿氧化物La0．7Ca0．3MnO3（LCMO）与Al复合体系的电磁输运性质．根据X射线衍射分析及电阻率与温度的关系可知,在（1-x）LCMO＋xAl（x代表物质的量）复合样品中,发现了新相Al2O3,且LCMO晶格常数和晶胞体积随Al掺量的增加而减小,同时在复合样品中出现了除对应LCMO本征金属-绝缘体转变峰TP,之外,在较低温度区域出现了另外一个转变峰TP2的现象,且复合样品转变峰T阳比LCMO本征金属-绝缘体转变峰TP1处于较宽的温度区域．经研究认为,在合成复合样品的实验过程中,既有Al被氧化为Al^3＋替代Mn^3＋的替代反应,也有Al经过高温与空气发生反应生成Al2O3,进而填隙在LCM0晶界处影响母体的电磁输运性质．本系列复合物中较宽温度区域CMR的发现为今后同类问题的研究提供了很好的实验基础．     

La0.7Ca0.3MnO3多晶材料制备及其电磁特性

以化学溶液分解法制备La0.7Ca0.3MnO3粉体,常压烧结制备多晶块体样品。对La0.7Ca0.3MnO3样品的磁矩、磁致电阻效应（CMR）和电脉冲诱导电阻转变效应（EPIR）进行了研究。磁矩零场冷和场冷试验结果发现,居里温度以下,零场冷和场冷条件下磁矩具有较大差别。这说明材料中缺少真正的长程磁有序。La0.7Ca0.3MnO3多晶具有磁致电阻效应,在9 T磁场作用下,磁致电阻变化大约为70%。在80 V,20 ns电脉冲作用下,材料具有电脉冲诱导电阻转变效应。从理论上对磁致电阻效应与电脉冲诱导电阻转变效应的机理进行了分析。     

亚锰酸盐La0.7-xYxCa0.3MnO3的电磁特性和磁电阻效应

研究了用固相反应法制备亚锰酸盐多晶样品La0.7-xYxCa0.3MnO3,并研究了Y的不同掺杂(x=0.1,0.2)对样品的晶体结构、电磁特性和磁电阻效应的影响.实验结果表明,随着温度的降低,x=0.1样品的R-T曲线没有出现峰值,而x=0.2样品出现了峰值,显示了复杂的输运特性.两种样品的磁电阻Rm都随着温度的降低而升高,但都没有出现峰值.x=0.2的样品在较宽的温区内,磁电阻效应都很显著,而且Y掺杂由x=0.1提高至x=0.2,磁电阻效应增强.     

DC and AC transport properties on La0.8Sr0.2MnO3

Railway Engineering Science - Magnetoresistive sensor can be widely used in modern transportation field, such as the vehicle positioning and navigation system, vehicle detection system, and...     

沉积温度对ZnO薄膜结构形貌及光学性能的影响

以Zn(NO3)2·6H2O为前驱体,采用超声喷雾热解法在玻璃衬底上沉积了ZnO薄膜,采用X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外光谱仪(UVS)等对所得ZnO薄膜进行表征,研究了沉积温度对ZnO薄膜的结构、微观形貌及光学性能的影响。结果表明,沉积温度为500℃时所制备的薄膜质量最佳,形成的是六角纤锌矿ZnO结构,且薄膜沿(002)晶面择优取向生长显著,薄膜表面光滑致密,晶粒细小均匀,尺寸在50~60nm。薄膜表现出良好的光学性能,可见光透过率可达87%。     

Sintering and Electronic Conducting Properties of Lao.7Ca0.3CrO3 Perovskite Synthesized by a Glycine-nitrate Process

La0.7 Ca0.3 CrO3 powder consisting of superfine and uniform particles （ 100-200 nm ） were synthesized using a glycine-nitrate process （ GNP ）. The sintering and electronic conducting properties of La0.7 Ca0.3 CrO3 were invetigated in the sintering temperature range of 1 200-1 450 ℃. The desired morphology of the powder significantly improved its sinterability. La0.7 Ca0.3 CrO3 ceramics sintered at 1 250-1 450 ℃ show high relative densities above 95 % . The ceramics sintered at 1 250-1 400 ℃ have very similar electronic conduct- ing properties, providing electronic conductivities around 55 Ω^-1 cm^-1 at a measuring temperature of 800 ℃ . Further increasing the sintering temperature to 1450 ℃ led to an apparent degradation of electronic conducting properties. This research demonstrates the advantage of the GNP in producing La0.7 Ca0.3 CrO3 with respect to the enhanced sintering properties and superior electronic conducting properties.     

Characterization and Electrochemical Properties of LiMn2O4 Thin Films Prepared by Solution Deposition

1 IntroductionThin-filmlithium-ion batteries have attracted greatattention of researchfor possible use inimplantable medi-cal devices , CMOS-based integrated circuits ,radio fre-quency (RF) identification tags for inventory control andanti-theft protection[1],etc. Li Mn2O4thin films , aspromising cathode materials for thin-filmlithium-ion bat-teries, have been prepared by a few methods such aspulsedlaser deposition[2 ,3],electrospraying[4-9],RF mag-netron sputtering[10], laser ablation[11]…     

水热法制备Ba0.7Sr0.3TiO3粉体

利用水热法研究了BST前驱物的初始配比、矿化剂NaOH过量浓度、水热时间和温度等条件对合成Ba0.7Sr0.3TiO3粉体的影响.实验结果表明在240℃下反应10h合成的立方相Ba0.7Sr0.3TiO3粉体,平均粒径为100nm左右,粉体粒度均一,团聚少,纯度高,杂质离子少.并用X射线衍射(XRD)、扫描电子显微镜(SEM)、激光粒度分析仪(LPS)等方法对合成粉体的物相和形貌进行了表征.     

电子束反应蒸发技术生长Mo掺杂In_2O_3薄膜

利用电子束反应蒸发技术,调制衬底温度200～350℃,详细研究了Mo掺杂In2O3(IMO,In2O3:Mo)薄膜的微观结构以及光电性能的变化。随着衬底温度增加,原子力显微镜(AFM)与扫描电子显微镜(SEM)图像均证明IMO薄膜表面趋于粗糙,透过率和Hall测试表明其光学和电学性能逐渐提高。在衬底温度为350℃时,获得薄膜最小电阻率为2.1×10-4Ωcm,载流子迁移率为34.2cm2/Vs,其可见光区及近红外区的平均透过率为78%。衬底温度为200℃时,薄膜表现为黑褐色,经分析X射线光电子能谱(XPS)结果认为与薄膜中钼的低价氧化有关,提高衬底温度可改善薄膜氧化状态。     

化学液相沉积法制备Al_xO_y薄膜

给出了用化学液相沉积法(CLPD)制备Al_xO_y/Si薄膜的方法,室温下生长2h得到Al_xO_y/Si薄膜,其退火温度为1000℃,退火时间2h。对薄膜的显微硬度、成分和结构进行了检测和分析。结果表明,薄膜的显微硬度在退火前为5202.0N/mm~2,退火后为14533.5N/mm~2,增加近3倍;高温退火去掉了膜内的OH~(-1),同时使薄膜晶化,晶体薄膜的O/Al比例为1.3。     

化学液相沉积法制备AlxOy薄膜

给出了用化学液相沉积法(CLPD)制备A1xOy／Si薄膜的方法，室温下生长2h得到A1xOy／Si薄膜，其退火温度为1000℃，退火时间2h．对薄膜的显微硬度、成分和结构进行了检测和分析．结果表明，薄膜的显微硬度在退火前为5202．0N／mm^2，退火后为14533．5N／mm^2，增加近3倍；高温退火去掉了膜内的0H^-1，同时使薄膜晶化，晶体薄膜的O／A1比例为1．3．     

La0.67Sr0.33Mn0.7Fe0.3O3的制备及其光催化性能研究

采用溶胶—凝胶燃烧法制备了纳米级钙钛矿型复合氧化物La_0.67Sr_0.33Mn_0.7Fe_0.3O₃,通过XRD、SEM对样品的物相和形貌进行表征,结果表明所得La_0.67Sr_0.33Mn_0.7Fe_0.3O₃样品为钙钛矿结构,直径约为50纳米,长度为1μm.以350 W氙灯做光源,催化降解亚甲基蓝水溶液,反应6 h,降解率达到96%.     

La1-xZnxMnO3和LaL2/3 Sr(1-x)/3 Znx/3 MnO3的磁电输运特性

用固相反应方法制备La1-xZnxMnO3和La2/3Sr(1-x)/3Znx/3MnO3化合物.La1-xZn MnO3在不同掺杂浓度x的研究表明:Zn2 在一定浓度范围内掺杂,具有钙钛矿结构,但掺杂浓度在50%～70%时有ZnO衍射峰,其电阻率在100 K以上随温度而下降,当掺杂浓度为x=0.3时电阻率最低.当Zn2 和Sr2 共掺而保持La3 浓度不变,即载流子浓度不变,维持Mn3 /Mn4 =2∶1,随Zn2 掺杂浓度增大,铁磁-顺磁转变温度降低,磁阻效应增大.低场磁阻效应与Zn2 掺杂浓度无关,而与温度有关;高场磁阻效应随掺杂浓度增大而增大.     

溶胶低温燃烧法制备Ba0.7Sr0.3TiO3纳米粉体

以Ba(NO3)2Sr(NO3)2TiO(NO3)2C6H8O7.H2O为反应体系,采用溶胶低温燃烧合成法制备了Ba0.7Sr0.3TiO3超细粉末。以正交试验考察了柠檬酸与金属离子物质的量比、溶胶pH值、燃烧及热处理温度对合成粉体粒径的影响,得到的工艺参数最优组合为:n(柠檬酸)∶n(金属离子)=1.5∶1,pH=7,燃烧及热处理温度为650℃。对比了溶胶燃烧法与凝胶燃烧法对BST粉末粒度和相结构的影响。应用X射线衍射和透射电镜等对粉体的相结构、粒径、形貌进行了分析和观察。     

空位掺杂(La(0.7-x)Y0.3)2/3Ca1/3MnO3的结构及其微观机制研究

利用标准的固相反应法在1 200℃烧结了(La(0.7-x)Y0.3)2/3Ca1/3MnO3(x=0,0.02,0.04,0.08,0.10)样品,冷却后,取出部分在1 350℃进行再烧结.利用X射线衍射(XRD)和扫描电镜(SEM)对其晶体结构及表面微观结构进行了研究.X射线衍射测量分析表明样品均为单相,单胞仍然具有正交对称性结构(空间群为Pnm a).通过扫描电镜研究表明,当化合物x=0.04时,(La(0.7-x)Y0.3)2/3Ca1/3MnO3的表面形貌表现为致密度最好.样品在1 350℃再烧结条件下,当x≤0.04时,可以大大降低样品的晶粒大小和孔隙;但当x>0.04时,再烧结对样品的晶体结构和表面微观结构影响不大.     

Microstructure and electrical properties of La2O3-doped ZnO-based varistor thin films by sol-gel process简

Microstructure and electrical properties of La2O3-doped ZnO-Bi2O3 thin films prepared by sol-gel process have been investigated. X-ray diffraction shows that most diffraction peaks of ZnO are equal, and the crystals of ZnO grow well. Scanning electron microscopy and atomic force microscopy results indicate that the samples have a good structure and lower surface roughness. The nonlinear V-I characteristics of the films show that La2O3 develops the electrical properties largely and the best doped content is 0.3% lanthanum ion, with the leakage current of 0.25 mA, the threshold field of 150 V/mm and the nonlinear coefficient of 4.0 in detail.     

Preparation and Properties of IrO2 Thin Films Grown by Pulsed Laser Deposition Technique

Highly conductive IrO2 thin films were prepared on Si （100） substrates by means of pulsed laser deposition technique from an iridium metal target in an oxygen ambient atmosphere. Emphasis was put on the effect of oxygen pressure and substrate temperature on the structure, morphology and resistivity of IrO2 films. It was found that the above properties were strongly dependent on the oxygen pressure and substrate temperature. At 20 Pa oxygen ambient pressure, pure polycrystalline IrO2 thin films were obtained at substrate temperature in the 300-500℃ range with the preferential growth orientation of IrO2 films changed with the substrate temperature. IrO2 films exhibited a uniform and densely packed granular morphology with an average feature size increasing with the substrate temperature. The room-temperature resistivity variations of IrO2 films correlated well with the corresponding film morphology changes. IrO2 films with the minimum resistivity of （42 ±6）μΩ·cm was obtained at 500℃.     

Sintering and Electronic Conducting Properties of La_(0.7)Ca_(0.3)CrO_3 Perovskite Synthesized by a Glycine-nitrate Process

1 IntroductionAlkaline earth metal (AE=Ca ,Sr) substitutedlan-thanumchromite perovskites have an excellent electronicconductivity,a negligible ionic conductivity and a goodchemical stability under bothoxidizingandreducingatmo-spheres at high temperatures . These desired propertiesmake themuseable as interconnectors of hightemperaturesolid oxide fuel cells (SOFCs)[1].The interconnectors ofSOFCs have atwo-foldfunction,providing electrical con-duction between individual cells and separating …