La2/3Sr1/3MnO3薄膜的输运及激光反射率特性

用磁控溅射方法制备了钙钛矿锰氧化合物La2/3Sr1/3MnO3(LSMO)单晶外延薄膜,该薄膜发生顺磁绝缘-铁磁金属相变的转变温度Tc≈330K.在室温(T=293K),偏置电流对LSMO薄膜输运性质的影响表明,随着电流的增大,材料的晶格畸变加强,电阻值增大,同时薄膜的激光反射率减小.用固体光学理论对其进行定性解释.     

(La,Pr)2/3Sr1/3MnO3薄膜激光诱导电阻效应

研究了钙钛矿锰氧化物La2/3Sr1/3MnO3和Pr2/3Sr1/3MnO3单晶薄膜的激光诱导电阻变化特性.低温铁磁金属相,激光诱导使薄膜的电阻增大,而在顺磁绝缘相则电阻减小,同时薄膜的绝缘体-金属相变(IMT)转变温度Tp向低温方向移动.对于Pr2/3Sr1/3MnO3薄膜,当激光功率为22mW时,光致电阻相对变化的最大值约为9.6%.光诱导效应致使薄膜的电阻发生变化,并使其IMT的转变温度点向低温方向移动,主要是由于光子能激发eg向下电子的跃迁,改变体系自旋极化方向.     

La2/3Sr1/3MnO3/ZnO混合物薄膜的磁电阻和伏安特性研究

利用脉冲激光沉积的方法在Si（100）氧化成SiO₂的基片上制备了(La_2/3Sr_1/3MnO₃)_x/(ZnO)_1-x混合物薄膜,研究了薄膜的磁电阻和伏安特性. X射线衍射分析表明,除了衬底SiO₂的衍射峰以外,分别出现了La_2/3Sr_1/3MnO₃（101）的衍射峰和ZnO（002）的衍射峰,且它们形成了两相共存体系. 实验表明：x=0.3的混合物薄膜表现为半导体导电特性,而x=0.4的样品则出现了典型的金属绝缘相变. 所制备的样品表现出了低场磁电阻效应和非线性伏安特性. 在0.7T磁场的作用下,x=0.3的样品在温度为60K时取得的最大磁电阻值为28.8%. 通过对伏安关系拟合表明,在La_2/3Sr_1/3MnO₃和ZnO颗粒之间存在一定的耗尽层,且产生了界面缺陷态.     

多铁性BaTiO3/La2/3Sr1/3MnO3复合薄膜的制备及其强磁电效应的研究

使用脉冲激光沉积技术,在(001)取向的LaAlO3(LAO)单晶基片上外延生长了BaTiO3/La2/3Sr1/3MnO3(BTO/LSMO)双层复合薄膜.电学和磁学性能的研究显示复合薄膜具有较低的相对介电常数(εr=263),优良的铁电和铁磁性能以及高于室温的铁磁居里温度(Tc=317 K).复合薄膜的磁电电压系数(αE)为176 mV/A,高于同类结构磁电系统一个数量级,相应的界面耦合系数k值为0.68,表明铁磁层和铁电层界面之间存在较大程度的耦合.     

不同厚度的La2/3Sr1/3MnO3多晶薄膜输运性质研究

运用磁控溅射的方法,在表面氧化的Si(100)基片上制备了一系列不同厚度的La2/3Sri/3MnO3多晶薄膜.根据对输运的研究,发现存在一个厚度73nm,当t＞73nm的时候,薄膜呈现出与块材类似的输运特点,而当t＜73nm的时候,薄膜的电阻太大以至于薄膜的金属-绝缘体转变温度(Tp)变得不可测量.X射线衍射(XRD)结果显示:在t=73nm附近存在一个结构的转变.这表明La2/3Sr1/3MnO3不同厚度多晶薄膜的输运性质的不同或许来自结构的转变.     

(Ca1-xSrx)[(Li1/3Nb2/3)0.95Zr0.15]3+δ陶瓷微波介电特性

研究了A位Sr2 取代对(Ca1-xSrx)[(Li1/3Nb2/3)0.95Zr0.15]3 δ(0.0≤x≤0.2,CSLNZ)陶瓷的微观结构及微波介电特性的影响.当0≤x≤20%(摩尔分数)时,体系为单一钙钛矿相,随Sr2 含量的增加,介电常数和谐振频率温度系数增大,而品质因素先增大,x=0.05时,开始下降.用键价理论分析了谐振频率温度系数随B位键价的变化关系.当Sr2 含量为5%(摩尔分数)时,陶瓷微波介电性能最佳:εr=32.5,Qf=13500GHz,τf=-2.4×10-6/℃.     

La2/3Sr1/3MnO3/ZnO混合物薄膜的磁电阻和伏安特性研究

利用脉冲激光沉积的方法在Si（100）氧化成SiO₂的基片上制备了(La_2/3Sr_1/3MnO₃)_x/(ZnO)_1-x混合物薄膜,研究了薄膜的磁电阻和伏安特性. X射线衍射分析表明,除了衬底SiO₂的衍射峰以外,分别出现了La_2/3Sr_1/3MnO₃（101）的衍射峰和ZnO（002）的衍射峰,且它们形成了两相共存体系. 实验表明：x=0.3的混合物薄膜表现为半导体导电特性,而x=0.4的样品则出现了典型的金属绝缘相变. 所制备的样品表现出了低场磁电阻效应和非线性伏安特性. 在0.7T磁场的作用下,x=0.3的样品在温度为60K时取得的最大磁电阻值为28.8%. 通过对伏安关系拟合表明,在La_2/3Sr_1/3MnO₃和ZnO颗粒之间存在一定的耗尽层,且产生了界面缺陷态.     

(La0.9Bi0.1)2/3Ca1/3MnO3磁性和电输运性质研究

利用固相反应法制备了(La0.9Bi0.1)2/3Ca1/3MnO3样品,研究了它的导电特性和磁性.在电阻和磁化测量中观察到热滞现象. 在电阻-温度(R-T)曲线中出现了两个峰,当施加5T外场时,电阻中的热滞现象被抑制,只观察到一个峰.磁化(M-T)曲线表明,在居里温度(Tc)以下发生了顺磁-铁磁(PM-FM)相变. 样品不同寻常的M-T行为能够很好地解释测量到的R-T曲线.     

Ba0.5Sr0.5 TiO3薄膜、Ba0.1Sr0.9 TiO3/YBa2 Cu3O7-δ异质薄膜的制备及介电性能研究

铁电钛酸锶钡(BSTO)薄膜具备十分优越的铁电/介电性能,在可调谐微波器件和动态随机存储器(DRAM)方面显示出十分诱人的应用前景.而YBa2Cu3O-δ(YBCO)高温超导薄膜作为其电极引入,明显降低了微波损耗,能够大大优化器件的性能.本文针对微波器件性能要求对比了各种常用基片的性能参数,描述了目前BSTO薄膜与BSTO/YBCO异质薄膜制备中存在的问题以及薄膜介电性能测试表征方法.利用脉冲激光沉积(PLD)技术成功制备出结构完整和质量较高的Ba0.5Sr0.5TiO3薄膜.同时,在1.2°斜切LaAlO3基片上研制有Ba0.1Sr0.9TiO3/YBa2Cu3O7-δ异质双层膜,在1MHz频率、77K温度条件下,其介电常数为1200,介电损耗为0.0045,±30V直流偏压时可调性达到60%,在液氮温度下表现出良好的应用前景.     

Pr2/3Sr1/3MnO3薄膜外场诱导自旋输运特性

采用脉冲激光沉积法制备了稀土掺杂钙钛矿锰氧化物Pr2/3Sr1/3MnO3(PSMO)外延薄膜,研究了薄膜在磁场、激光和电流作用下的自旋输运特性.在低温铁磁金属相,激光作用使薄膜的电阻增大,而磁场和电流则诱导电阻减小;在高温顺磁绝缘态,外场诱导均使电阻减小.在铁磁金属相,外场诱导输运特性的变化可归结于外场对体系电子自旋系统的影响:磁场和电流加强材料中eg电子和t2g局域电子间的自旋平行,增强了双交换作用;激光作用可产生光致退磁效应,减弱双交换作用.在顺磁绝缘态,场致电阻降低源于外场致使小极化子的退局域化效应.     

Fabrication, characterisation and application of (8 mol% Y2O3) ZrO2 thin film on Na3Zr2Si2PO12 substrate for sensing CO2 gas

A planar type CO₂ gas sensor employing (8 mol% Y₂O₃) ZrO₂ (YSZ) thin film on Na₃Zr₂Si₂PO₁₂ (Nasicon) substrate with Na₂CO₃ as an auxiliary electrode has been fabricated and tested in laboratory environment between 700–900 K. The YSZ thin film was fabricated on Nasicon and alumina substrate using radio frequency (RF) magnetron sputtering. The film was examined using SEM and X-ray diffraction (XRD) after treating the Nasicon-YSZ bi-layer structure at 1300 K for 2 h. The results indicate that a crack free YSZ film was produced on Nasicon surface that was well bonded to the substrate. The conductivity of sputtered YSZ thin film measured by ac-impedance spectroscopy has been found to be higher than that of YSZ pellet by approximately half an order of magniture. The bi-electrolyte planar sensor displays rapid response (t₉₅ 200 s) to CO₂ compared to the tube type sensor (t₉₅ 700 s) and the measured open circuit voltage of the electrochemical CO₂ sensor has been found to be Nernstian at all temperatures.     

Investigation into the growth and electromechanical properties of Pb(Mg1/3Nb2/3)O3 thin films

Pulsed laser deposition (PLD) has been used to fabricate relaxor thin films and thin film capacitors based on the Pb(Mg_1/3Nb_2/3)O₃ system. Best capacitor structures show dielectric constants (_r) of 1000 and losses (tan ) 0.02 at 1 kHz at 300 K. Electromechanical investigations show that tensile longitudinal strains of up to 0.2% can be achieved in these films.     

Effect of vacuum annealing on the phase composition of In/SnO/Si, In/SnO2/Si, and Sn/In2O3/Si heterostructures

The chemical interaction between indium and thin SnO and SnO₂ films and between tin and thin In₂O₃ films during vacuum annealing was studied. The metallic films were deposited onto single-crystal silicon substrates by magnetron sputtering, the SnO and SnO₂ films were produced by heat-treating the Sn film in flowing oxygen at 673 and 873 K, respectively, and the In₂O₃ film was produced by heat-treating the In film at 573 K. The results indicate that annealing of the In/SnO/Si and In/SnO₂/Si heterostructures in vacuum (residual pressure of 0.33 × 10^?2 Pa) at 773 K gives rise to the reduction of Sn and oxidation of In, whereas annealing of Sn/In₂O₃/Si causes partial tin substitution for indium in the cubic indium oxide lattice.     

Influence of surface modification of alumina on bond strength in Al2O3/Al/Al2O3 joints

The subject of the work was to study the effect of Ti thin film on alumina ceramic on mechanical strength and fracture character of Al₂O₃/Al/Al₂O₃ joints. The joints were formed by liquid state bonding of alumina substrates covered with titanium thin film of 800 nm thickness using Al interlayer of 30μm thickness at temperature of 973 K in a vacuum of 0.2 mPa for 5 min. The bend strength was measured by four–point bending test at room temperature. Scanning and transmission electron microscopy were applied for detailed characterization of interface structure and failure character of fractured joint surfaces. Result analysis has shown that application of the Ti thin film on alumina leads to decrease of bond strength properties of Al₂O₃/Al/Al₂O₃ joints along with the change either of structure and chemistry of interface or of failure character.     

Fabrication and Optical Properties of Pb(Mg/sub 1/3/Nb/sub 2/3/)O/sub 3/-PbTiO/sub 3/Thin Films on Si Substrates Using the PLD Method

Epitaxial 0.67Pb(Mg_1/3Nb_2/3)O₃-0.33PbTiO₃ (PMN-PT) thin films with electro-optic effects were fabricated on (La_0.5Sr_0.5)CoO₃(LSCO)/CeO₂/YSZ-buffered Si(001) substrates using double-pulse excitation pulsed laser deposition (PLD) method with a mask placed between the target and the substrate. Epitaxial growth of PMN-PT thin films was undertaken using the two-step growth method of PMN-PT film. The PMN-PT seed layer was deposited at 500degC on the LSCO/CeO₂/YSZ/Si, which temperature was the same as that used for LSCO deposition. The PMN-PT thin films were deposited on the PMN-PT seed layer at 600degC, which enables growth of high-crystallinity PMN-PT films with smooth surfaces. We obtained optimum fabrication conditions of PMN-PT film with micrometer-order thickness. Resultant films showed high crystallinity with full width at half maximum (FWHM)=0.73 deg and 1.6 mum thickness. Electro-optic properties and the refractive index value were measured at 633 nm wavelength using the prism coupling method. The obtained refractive index was 2.59. The electro-optic coefficients r₁₃ and r₃₃ were determined by applying the electrical field between a semitransparent, thin top electrode of Pt and a bottom LSCO electrode. The electro-optic coefficient was r₁₃=17 pm/V at transverse electric field (TE) mode and r₃₃=55 pm/V at transverse magnetic field (TM) mode.     

Structure and electrical properties of (100)-oriented Pb(Zn1/3Nb2/3)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 thin films on La0.7Sr0.3MnO3 electrode by chemical solution deposition

(100)-oriented 0.462Pb(Zn_1/3Nb_2/3)O₃–0.308Pb(Mg_1/3Nb_2/3)O₃–0.23PbTiO₃ (PZN-PMN-PT) perovskite ferroelectric thin films were prepared on La_0.7Sr_0.3MnO₃/LaAlO₃ (LSMO/LAO) substrate via a chemical solution deposition route. The perovskite LSMO electrode was found to effectively suppress the pyrochlore phase while promote the growth of the perovskite phase in the PZN-PMN-PT film. The film annealed at 700 °C exhibited a high dielectric constant of 2130 at 1 kHz, a remnant polarization, 2P_r, of 29.8 μC/cm², and a low leakage current density of 7.2 × 10^− 7 A/cm² at an applied field of 200 kV/cm. The ferroelectric polarization was fatigue-free at least up to 10¹⁰ cycles. Piezoelectric coefficient, d₃₃, of 48 pm/V was also demonstrated. The results showed that much superior properties could be achieved with the PZN-PMN-PT thin films on the solution derived LSMO electrode than on Pt electrode by sputtering.     

Thermoelectric properties of Sb2Te3 thin films by electron beam evaporation

This study applies the thermoelectric grains of Sb2Te3 on conductive glass to evaporate Sb2Te3 thin films by the electron beam evaporation method. Through experimental tests with different evaporation process parameters and film annealing conditions, thin films with better Seebeck coefficient, resistivity (p) and power fact (PF) can be obtained. Experimental results show that when thin films are annealed, their defects can be decreased accordingly, and carrier mobility can be enhanced to further elevate the conductivity of thin films. When the substrate temperature is set at 200 degrees C to fabricate Sb2Te3 thin films by the evaporation process and by annealing at 220 degrees C for 60 minutes, the Seebeck coefficient of Sb2Te3 thin films increase from 87.6 microV/K to 177.7 microV/K; resistivity falls from 6.21 m ohms-cm to 2.53 m ohms-cm and PF can achieve the maximum value of 1.24 10(-3) W/K2 m. Finally, this study attempts to add indium (In) to Sb2Te3 thin films. Indium has been successfully fabricated In3SbTe, thin films. This study also analyzes the effects of In on the thermoelectric properties of In3SbTe2 thin films.