Low temperature Raman study of PrCoO3 thin films on LaAlO3 （100） substrates grown by pulsed laser deposition

Thin films of PrCoO₃ were deposited on LaAlO₃ substrates by pulsed laser deposition technique. X-ray diffraction result indicates that films are single phase and c-axis textured. To investigate the spin state transition, Raman spectroscopy measurements were performed at different temperatures. The position of the Raman modes is found to increase while full width at half maximum (FWHM) of these modes is found to decrease with the decrease of temperature across spin state transition temperature (220 K) of PrCoO₃.     

钽铌酸锂单晶的喇曼光谱分析

利用刺曼散射方法系统地研究了钽铌酸锂晶体的晶体振动及其高温下发生的由铁相到顺电相的结构相变,常温实验中,观察了所有喇曼激活模式软化,与群论分析的结果相符合。     

用掺杂方法改变VO_2多晶薄膜相变温度研究

用离子束增强沉积方法对二氧化钒多晶薄膜作Ar和W掺杂,明显改变了二氧化钒薄膜的相变温度。研究表明,成膜时注入的氩在二氧化钒结构形成前就很快外释,掺杂Ar对相变温度降低的贡献主要来自间隙Ar。W原子的掺杂可有效地将二氧化钒多晶薄膜的相变温度降低到室温附近,为大幅提高薄膜的室温电阻-温度系数提供了可能。     

溶胶-凝胶法制备掺镧钛酸钡薄膜及其光学性质研究

以硝酸镧、醋酸钡、钛酸四丁酯为原料,采用溶胶一凝胶旋涂法制备掺La的钛酸钡薄膜,研究薄膜的晶体结构、表面形貌、紫外-可见光吸收性能及光学带隙。研究结果表明,纯钛酸钡和掺La钛酸钡薄膜均为单一四方钙钛矿结构,La3＋的引入可以使钛酸钡薄膜在可见光区的透过率和光学带隙有一定程度下降,而退火温度对掺镧钛酸钡薄膜光学带隙基本无...     

Impacts of hydrogen dilution on growth and optical properties of a-SiC:H films

Hydrogenatedamorphoussiliconcarbon(a-SiC:H)filmshavefoundagreatdealofusesinsolarcells[1],thinfilmtransistors[2],lightemittingdiodes[3],ultravioletimagesensors[4],microfluidiccoatings[5]andprotectivebarrierforcorrosionorthermaloxidation[6,7],becauseofitsuniquepropertiessuchaswideopticalbandgap,highmechanicalhardnessandchemicalstability.However,astheCcontentincreases,theelectronicandstructuralpropertiesofthefilmstendtobeinferior[8].Althoughinrecentyearsmuchworkhasbeendevotedtoexploringthedeposi…     

不同抗衡阴离子自旋交叉分子的制备与表征

基于三氮唑（1,2,4-1H-triazole,Htrz）体系的Fe（II）的配合物是一类非常重要的在室温附近发生自旋转变的自旋交叉分子,具有潜在的应用。本文报道了2种基于三氮唑体系的Fe（II）的配合物的制备与表征,分别为［Fe（Htrz）₂（trz）］（CF₃SO₃）和［Fe（Htrz）₂（trz）］（BF₄）,并研究了抗衡阴离子对自旋转变行为的影响。自旋交叉分子的制备由2种前驱体简单混合反应而得,结构表征表明三氮唑参与反应,并且产物中的Fe元素基本为Fe（II）,磁性测试证实了这2种分子存在自旋转变特性,并且这种自旋转变具有温度磁滞效应。实验结果还表明抗衡阴离子对于自旋交叉分子的自旋转变行为有重要的影响。抗衡阴离子空间位阻越小、抗衡阴离子的电负性越强、结构越对称规整,则自旋转变温度越高。     

Transport properties and microstructure of La0.7Sr0.3MnO3 nanocrystalline thin films grown by polymer-assisted chemical solution deposition

Perovskite-based materials can be widely used in the aerospace and transportation field. Perovskite manganese oxides La_0.7Sr_0.3MnO₃ (LSMO) thin films were grown on LaAlO₃ (100) and Si (100) single crystal substrates by the polymer-assisted chemical solution deposition (PACSD) method. Electronic transport behavior, microstructure, and magnetoresistance (MR) of LSMO thin films on different substrates were investigated. The resistance of LSMO films fabricated on LaAlO₃ substrates is smaller than that on the Si substrates. The magnetic field reduces resistance of LSMO films both on Si and LAO in the wide temperature region, when the insulator-metal transition temperature shifts to higher temperature. The low-field magnetoresistance of LSMO films on Si in low temperature range at 1 T is larger than that of LSMO films on LAO. However, the MR of LSMO film on LAO films at room-temperature is about 5.17 %. The thin films are smooth and dense with uniform nanocrystal size grain. These results demonstrate that PACSD is an effective technique for producing high quality LSMO films, which is significant to improve the magnetic properties and the application of automotive sensor.

     

Preparation of Bi2-xSbxTe3 thermoelectric films by electrodeposition

1. Introduction In the last decade, green power sources have attract- ed much attention because of severe environmental problem. As a green power source, the greatest virtue of a thermoelectric power generator is that it makes use of all kinds of heat (so…     

Fabrication of Poly-Si Thin Film on Glass Substrate by Aluminum-induced Crystallization

Amorphous silicon （ a-Si ） thin films were deposited on glass substrate by PECVD, and polycrystalline silicon （ poly- Si ） thin films were prepared by aluminum- induced crystallization （ AlC ）. The effects of annealing temperature on the microstructure and morphology were investigated. The AlC poly-Si thin films were characterized by XRD, Raman and SEM. It is found that a-Si thin film has a amorphous structure after annealing at 400℃ for 20 min, a-Si films begin to crystallize after annealing at 450 ℃ for 20 min, and the crystallinity of a-Si thin films is enhanced obviously with the increment of annealing termperature.     

基于拉曼光谱的类金刚石薄膜的热稳定性研究

利用阴极真空弧放电设备制备了表面光滑的类金刚石薄膜材料,通过多波长激发的拉曼光谱研究了不同退火条件下所制薄膜的热稳定性.实验结果表明,在小于400℃的温度处理下,类金刚石薄膜微观结构几乎不发生变化,薄膜处于稳定区;当温度升高至600℃,微观结构开始发生微妙的变化,认为处于亚稳定区;当温度升至800℃甚至1 000℃时,类金刚石薄膜的微观结构发生显著变化,薄膜开始出现石墨化,物理性质不能保持稳定.     

B_2O_3对硼硅酸盐玻璃结构和性能的影响

硼硅酸盐玻璃与普通的钠钙硅玻璃相比,性能上有非常明显的优势。主要探讨B2O3对硼硅酸盐玻璃结构和性能的影响。通过红外光谱和拉曼光谱分析了硼硅酸盐玻璃在不同含量B2O3的情况下的结构变化,测试了玻璃的热膨胀系数、转变温度、软化温度和化学稳定性。研究结果表明:随着B2O3含量的增加,玻璃结构中[BO3]增多,[BO4]先增多后相当,玻璃的热膨胀系数也是先减小后增大,转变温度和软化温度都逐渐减小;硼硅酸盐玻璃中加入适量的B2O3后对玻璃的化学稳定性有一定的改善。     

Preparation of nanocrystalline BaTiO_3 ceramics

The high-dense nanocrystalline BaTiO3(BT)ceramics with grain size smaller than 100nm have been successfully prepared by the two step sintering and the spark plasma sintering(SPS)process.The successive transitions in nanograin BT ceramics from rhombohedral to orthorhombic,tetragonal and cubic transitions,similar to those in coarse BT ceramics,were revealed by in-situ temperature dependent Raman spectrum.The multiphase coexistence and the diffused phase transition character were demonstrated in the 8nm nanocr...     

CuxS(x=1,2)纳米薄膜的异步脉冲超声喷雾热解法制备

采用改进的异步脉冲超声喷雾热解技术在玻璃衬底上成功地制备了CuxS(x =1,2 )纳米薄膜 .研究发现 ,所制备的CuxS薄膜为多晶态 ;薄膜的晶相结构依赖于CuCl2 ·2H2 O和硫脲的摩尔比及衬底温度 .XRD和XPS分析表明 :样品为纯CuxS(CuS ,Cu2 S) ,拉曼谱研究表明其峰位分别在 472cm- 1 (Cu2 S)和 474cm- 1 (CuS)处 .     

红外光谱研究十八胺、硬脂酸及氘代硬脂酸Langmuir-Blodgett膜相变行为

分别制备十八胺、硬脂酸及氘代硬脂酸的11层Langmuir-Blodgett（LB）膜,采用变温傅立叶变换红外光谱研究了3种LB膜的相变行为.实验结果显示：十八胺LB膜在55℃～75℃温度区间内发生相变,CH2对称和反对称伸缩振动频率向高能量区移动较明显;硬脂酸LB膜在较短温度区间即70℃～80℃内发生明显相转变,CH2对称和反对称伸缩振动频率及峰的强度比在此温度区间发生显著改变;氘代硬脂酸LB膜的相转变在65℃～75℃温度区间内发生,尤其是在65℃～70℃的温度区间发生突变.     

MPECVD法在抛光石英玻璃上沉积金刚石薄膜

采用微波等离子体增强化学气相沉积方法(MPECVD),利用氢气和甲烷混合气体,在抛光石英基片上低温沉积出金刚石薄膜。用扫描电子显微镜(SEM)、激光拉曼光谱仪(Raman)和傅立叶红外光谱仪(FTIR)对薄膜的表面形貌、颗粒尺寸、纯度和光学透过性能进行了表征。通过SEM发现,得到的金刚石薄膜的颗粒尺寸为0.2~0.3μm,形核密度超过109cm-2,从薄膜形貌可以发现,较高温度有利于提高薄膜的生长速率和颗粒尺寸的均匀性。通过拉曼光谱和红外透射光谱分析发现,较高温度下沉积的薄膜具有较高的金刚石相含量,薄膜的光学透过性能也相对较好。     

Stokes与Antistokes喇曼散截面的温度依赖关系

论述了stokes与antistokes过程喇曼散射截面的温度依赖关系.将这种关系应用于LiNbO_3晶体样品温度的原位测量,发现这种测量温度的方法有较高的精度,对于一些难于直接测温的样品很有效.通过对BaTiO_3喇曼散射514cm~(-1)峰stokes及antistokes相对散射强度的比较,结果BaTiO_3的铁电相变更接近于有序-无序型机制.     

单相BaCeO_3陶瓷的制备研究

采用冷压陶瓷技术在不同烧结温度下制备BaCeO3陶瓷.利用X射线衍射(XRD)和拉曼光谱(RS)研究烧结温度对CeO2在BaCeO3陶瓷形成中的固溶性及单相陶瓷形成的影响.研究表明:在1100～1450℃范围内,XRD和RS观测都证实了少量CeO2的残存.当烧结温度增加到1480℃并保持长时间烧结时,CeO2能够完全固溶,以CeO2位于33.07°的(200)XRD峰和460 cm-1处拉曼带的消失为标志,形成具有Pnma正交钙钛矿结构的单相BaCeO3陶瓷.Ba蒸发效应被讨论,Ba位不足由极少量的Ce3B a+-Ce3T i+形成来自补偿.     

Dielectric properties of Pb (Zn_(1/3) Nb_(2/3)) O_3-PbZrO_3-PbTiO_3 solid solution near morphotropic phase boundary

The dielectric properties of Pb(Zn1/3Nb2/3)O3-PbZrO3-PbTiO3(PZN-PZ-PT) system near the rhombohedral/tetragonal morphotropic phase boundary (MPB) are carefully studied in this paper. It is found that, for all samples, the curves around the temperatures of dielectric permittivity peak show the characteristics of diffuse phase transition. The change in PbZrO3/PbTiO3 ratio has much influence on the dielectric properties of the samples. The extent of diffuse phase transition increases with the increasing Zr/Ti ratio. The samples in rhombohedral region have typical diffuse phase transition in the temperature range measured. However, for the samples with tetragonal symmetry, a spontaneous normal ferroelectric-relaxor phase transition exists at temperature lower than that of permittivity peak. This normal ferroelectric-relaxor phase transition is confirmed by the experiment of thermally driven current . The analysis of TEM reveals that the samples in tetragonal region show a 90° macrodomain structure , while th     

Infrared thermochromic properties of VO2 thin films prepared through aqueous sol-gel process

The stoichiometric vanadium(IV) oxide thin films were obtained by controlling the temperature, time and pressure of annealing. The thermochromic phase transition and the IR thermochromic property of 400 nm and 900 nm VO2 thin films in the 7.5 μm-14 μm region were discussed. The derived VO2 thin film samples were characterized by Raman, XRD, XPS, AFM, SEM, and DSC. The resistance and infrared emissivity of VO2 thin films under different temperature were measured, and the thermal images of films were obtained using infrared imager. The results show that the VO2 thin film annealed at 550 ℃ for 10 hours through aqueous sol-gel process is pure and uniform. The 900 nm VO2 thin film exhibits better IR thermochromic property than the 400 nm VO2 thin film. The resistance of 900 nm VO2 film can change by 4 orders of magnitude and the emissivity can change by 0.6 during the phase transition, suggesting the outstanding IR thermochromic property. The derived VO2 thin film can control its infrared radiation intensity and lower its apparent temperature actively when the real temperature increases, which may be applied in the field of energy saving, thermal control and camouflage.     

双层亚铁磁磁性薄膜的磁矩研究

采用Heisenberg模型,利用线性自旋波近似和格林函数技术研究双层亚铁磁薄膜的磁矩,分析自旋量子数、层间交换耦合、各向异性参数及温度对双层亚铁磁薄膜磁矩的影响.零温时,层内交换耦合和各向异性不影响薄膜的磁矩.低温时（温度小于等于居里温度的三分之一）,当两格点的自旋量子数相等时,薄膜的磁矩不受层间交换耦合的影响,但随各向异性的增加而增加;当两格点的自旋量子数不等时,薄膜的磁矩随层间交换耦合和各向异性的增加而增加.零温时,两格点的自旋偏差（或量子波动）相等.