共查询到20条相似文献,搜索用时 15 毫秒
1.
R. Kita S. Nakamura K. Sakimoto T. Nakamura O. Miura K. Matsumoto P. Mele K. Yamada K. Kaneko A. Ichinose 《Physica C: Superconductivity and its Applications》2010,470(20):1198-1200
We investigated the effects of indium doping on the superconducting properties of YBCO sintered samples and thin films. In2O3-doped YBCO and YBa2Cu3−xInxOy sintered samples showed a gradual decrease in the critical temperature (Tc) with increasing indium content; however, a Tc value above 80 K was maintained even up to 30 vol.% addition and x = 0.4, respectively. Ba3Cu3In4O12 was detected by X-ray diffractometry and energy-dispersive X-ray spectroscopy as a reaction product for both sintered samples. The normalized Jc under a magnetic field of 0.1 T showed a maximum at x = 0.3. Indium-doped YBCO films prepared by pulsed laser deposition showed a similar dependence of Tc on indium content as the sintered samples. 相似文献
2.
We have performed low-temperature scanning tunneling microscopy (STM) experiments on the cold-cleaved surface of YBa2Cu3Oy single crystals to study the nanoscale electronic order in high-Tc superconductors. STM images measured at low-bias voltage below ∼50 meV show the one-dimensional (1D) electronic modulation along the Cu-O bonds (parallel to the b-axis). The 1D electronic modulation does not have long-range order and the periodicity along the a-axis varies within the range ∼2a-4a depending on the position on the surface, indicating the glassy electronic order in the underdoped CuO2 plane. 相似文献
3.
Gaolin Zheng Huaping Song Yan Guo Caihong Jia Chunmei Jiao Shaoyan Yang Qinsheng Zhu Zhanguo Wang 《Applied Surface Science》2010,256(8):2606-8120
Post-growth annealing was carried out on ZnO thin films grown by metal-organic chemical vapor deposition (MOCVD). The grain size of ZnO thin film increases monotonically with annealing temperature. The ZnO thin films were preferential to c-axis oriented after annealing as confirmed by X-ray diffraction (XRD) measurements. Fourier transformation infrared transmission measurements showed that ZnO films grown at low temperature contains CO2 molecules after post-growth annealing. A two-step reaction process has been proposed to explain the formation mechanism of CO2, which indicates the possible chemical reaction processes during the metal-organic chemical vapor deposition of ZnO films. 相似文献
4.
利用脉冲激光沉积技术在LaAlO3(00l)单晶衬底上制备了La067Ba033MnO3薄膜,研究了CO2激光辐照对La067Ba033MnO3薄膜的微结构和磁电性能的影响.结果表明,经激光辐照后,La067Ba033MnO3薄膜的结晶性增强,薄膜应变减小;薄膜表面形貌由“岛状”结构变为“平原"结构,且粗糙度大大降低;同时,薄膜的饱和磁化强度、铁磁居里温度、金属—绝缘态转变温度和磁电阻增大,而矫顽场和电阻率减小.根据对传统退火效应的分析和理论计算,认为激光辐照导致的表面微结构的变化以及薄膜的氧含量和均匀性的提高对La067Ba033MnO3薄膜的磁电性能的改善与优化密切相关.
关键词:
庞磁电阻
激光辐照
脉冲激光溅射沉积 相似文献
5.
Bismuth sulfide (Bi2S3) films were chemically deposited by a novel deposition system in which ammonium citrate was used as the chelating reagent. Two sulfur source thioacetamide (TA) and sodium thiosulfate (Na2S2O3) were used to prepare Bi2S3 films. Both the as-prepared films have amorphous structure. However, annealing can improve the crystallization of the films. The composition of the films prepared by TA and Na2S2O3 are all deviate from the stoichiometric ratio of Bi2S3. The Bi2S3 films are all homogeneous and well adhered to the substrate. The optical properties of the Bi2S3 films are studied. The electrical resistivity of the as-prepared films are all around 7 × 103 Ω cm in dark, which decreases to around 1 × 103 Ω cm under 100 mW/cm2 tungsten-halogen illumination. After the annealing, the dark resistivity of the Bi2S3 film prepared by TA decreases by four magnitudes. In contrast, the dark resistivity of the Bi2S3 film prepared by Na2S2O3 only decreases slightly. 相似文献
6.
Nanowall shaped Bi2S3 films were prepared by chemical bath deposition in which ammonium citrate and thioacetamide were used as chelating reagent and sulfur source, respectively. The nanowall Bi2S3 films show large-surface-area nanowall shaped morphology. It is found that the pH value (pH = 6 or pH = 6.5) of the solution is a crucial parameter to obtain the nanowall shaped Bi2S3 films. The composition of the nanowall Bi2S3 films is close to the stoichiometric ratio of Bi2S3. The absorption edge of the nanowall shaped Bi2S3 films is located at around 900 nm, indicating that the optical bandgap of the Bi2S3 films is around 1.4 eV. The nanowall Bi2S3 films show obvious photo-sensitivity. The photo-to-dark conductivity ratios of the nanowall Bi2S3 films prepared at pH = 6 and pH = 6.5 are all around 50. This value is around five times than that of the non-nanowall shaped Bi2S3 films which is prepared at pH = 7. 相似文献
7.
Hou Yan-chaoHuang Jian-feng Zhou XuanCao Li-yun Wu Jian-peng 《Applied Surface Science》2012,258(8):3882-3887
Sm2S3 thin films were prepared on Si (1 0 0) substrates using SmCl3 and Na2S2O3 as precursors by liquid phase deposition method on self-assembled monolayers. The influence of the molar concentration ratio of [S2O32−]/[Sm3+] on the phase compositions, surface morphologies and optical properties of the as-deposited films were investigated. The as-deposited Sm2S3 thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), ultraviolet-visible (UV-vis) and photoluminescence spectrum (PL). Results show that it is important to control the [S2O32−]/[Sm3+] during the deposition process and monophase Sm2S3 thin films with orientation growth along (0 1 1) direction can be achieved when [S2O32−]/[Sm3+] = 2.0, pH 3.0, with citric acid as a template agent. The as-deposited thin films exhibit a dense and crystalline surface morphology. Good transmittance in the visible spectrum and excellent absorbency of ultraviolet light of the thin films are observed, and the band gap of the thin films first decrease and then increase with the increase of the [S2O32−]/[Sm3+]. The as-deposited thin films also exhibit red photoluminescence properties under visible light excitation. With the increase of the [S2O32−]/[Sm3+] in the deposition solution, the PL properties of Sm2S3 thin films are obviously improved. 相似文献
8.
9.
Rakhi Khandelwal Avinashi Kapoor Sorin Grigorescu Nadya Evgenieva Stankova 《Optics & Laser Technology》2009,41(1):89-11417
Tin oxide (SnO2) thin films were grown on Si (1 0 0) substrates using pulsed laser deposition (PLD) in O2 gas ambient (10 Pa) and at different substrate temperatures (RT, 150, 300 and 400 °C). The influence of the substrate temperature on the structural and morphological properties of the films was investigated using X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). XRD measurements showed that the almost amorphous microstructure transformed into a polycrystalline SnO2 phase. The film deposited at 400 °C has the best crystalline properties, i.e. optimum growth conditions. However, the film grown at 300 °C has minimum average root mean square (RMS) roughness of 3.1 nm with average grain size of 6.958 nm. The thickness of the thin films determined by the ellipsometer data is also presented and discussed. 相似文献
10.
Dongxiang ZhouGang Jian Yanan Zheng Shuping GongFei Shi 《Applied Surface Science》2011,257(17):7621-7626
Electrophoretic deposition was utilized for preparation of BaTiO3/CoFe2O4 multiferroic composite thick films on indium-tin oxide substrates. The suspensions for electrophoretic experiments were prepared by dispersing BaTiO3 and CoFe2O4 nanoparticles with different molar ratios into solvents composed of ethanol and acetylacetone. Polyvinyl butyral was added to the suspensions in order to enhance the adhesion and strength of deposit and prevent cracking. The zeta potential values of BaTiO3/CoFe2O4 suspensions were measured to be 26.4-36.9 mV. The experiment results showed that deposited films were obtained only when the applied electric field was larger than a certain critical value. XRD and SEM analysis depicted the presence of constituent phases in composite films. The percolation threshold of composite films was improved through dispersing ferromagnetic phase into ferroelectric phase. Therefore, the ferroelectric properties of composite thick films were maintained when the ferromagnetic properties were enhanced significantly with increasing CFO content. 相似文献
11.
Hai Guo Xudong Yang Teng Xiao Weiping Zhang Liren Lou Jacques Mugnier 《Applied Surface Science》2004,230(1-4):215-221
Pure and rare earth doped gadolinium oxide (Gd2O3) waveguide films were prepared by a simple sol–gel process and dip-coating method. Gd2O3 was successfully synthesized by hydrolysis of gadolinium acetate. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were used to study the thermal chemistry properties of dried gel. Structure of Gd2O3 films annealed at different temperature ranging from 400 to 750 °C were investigated by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that Gd2O3 starts crystallizing at about 400 °C and the crystallite size increases with annealing temperature. Oriented growth of (4 0 0) face of Gd2O3 has been observed when the films were deposited on (1 0 0) Si substrate and annealed at 750 °C. The laser beam (λ=632.8 nm) was coupled into the film by a prism coupler and propagation loss of the film measured by scattering-detection method is about 2 dB/cm. Luminescence properties of europium ions doped films were measured and are discussed. 相似文献
12.
The antimony doped tin oxide (SnO2:Sb) (ATO) thin films were prepared by oblique angle electron beam evaporation technique. X-ray diffraction, field emission scanning electron microscopy, UV-vis-NIR spectrophotometer and four-point probe resistor were employed to characterize the structure, morphology, optical and electrical properties. The results show that oblique angle deposition ATO thin films with tilted columns structure are anisotropic. The in-plane birefringence of optical anisotropy is up to 0.035 at α = 70°, which means that it is suitable as wave plate and polarizer. The electrical anisotropy of sheet resistance shows that the sheet resistance parallel to the deposition plane is larger than that perpendicular to the deposition plane and it can be changed from 900 Ω/□ to 3500 Ω/□ for deposition angle from 40° to 85°, which means that the sheet resistance can be effectively tuned by changing the deposition angle. Additionally, the sandwich structure of SiO2 buffer layer plus normal ATO films and oblique angle deposition ATO films can reduce the resistance, which can balance the optical and electrical anisotropy. It is suggested that oblique angle deposition ATO thin films can be used as transparent conductive thin films in solar cell, anti-foggy windows and multifunctional carrier in liquid crystal display. 相似文献
13.
Bi2Te3 is one of the most used materials for thermoelectric applications at ambient temperature. An improvement of thermoelectric performances through a suitable modification of electron and phonon transport mechanisms is predicted for low dimensional or nanostructured systems, but this requires a control of the material structure down to the nanoscale. We show that pulsed laser deposition provides control on film composition, phase and structure, necessary for a comprehension of the relationship between structure and thermoelectric properties. We have explored the role of deposition temperature, background inert gas type and pressure, laser fluence and target-to-substrate distance and we found the experimental condition ranges to obtain crystalline films containing the Bi2Te3 phase only, by comparing energy dispersive X-ray spectroscopy, Raman spectroscopy and X-ray diffraction analysis. Variations of substrate temperature and deposition gas pressure prove to be crucial also for the control of film morphology and crystallinity. Substrate type has no influence on film stoichiometry and crystallinity, but highly oriented growth can be achieved on mica due to van der Waals epitaxy. 相似文献
14.
利用高温固相法合成Na_2CaSiO_4:Sm~(3+),Eu~(3+)系列荧光粉末,研究了Sm~(3+)和Eu~(3+)掺杂对Na_2CaSiO_4晶体结构的影响、材料发光特性以及存在的能量传递现象.X射线衍射结果表明Sm~(3+)和Eu~(3+)单掺及共掺样品均为单相的Na_2CaSiO_4结构,晶体结构没有改变.Na_2CaSiO_4:Sm~(3+)荧光样品在404 nm激发波长下呈现峰峰值为602 nm的橙红色荧光,来源于~4G_(5/2)→~6H_(7/2)跃迁.Na_2CaSiO_4:Eu~(3+)荧光样品在395 nm激发波长下发射出峰峰值为613 nm的红色荧光.对光谱和荧光寿命的测试和分析结果表明Sm~(3+)与Eu~(3+)之间存在能量传递,通过理论计算得到Sm~(3+)和Eu~(3+)之间的能量传递临界距离为1.36 nm,相互作用形式为电四极-电四极相互作用.随着Eu~(3+)掺杂浓度的增加,能量传递效率也逐渐提高至20.6%. 相似文献
15.
Tetragonal lead titanate (PbTiO3, PT) thin films are grown on (1 0 0) MgO substrate by pulsed-laser deposition (PLD) for expected applications in integrated optics. The realisation of outstanding and reliable devices into integrated circuits requires sufficient mechanical resistance despite that the obtained PT films display interesting waveguiding properties associated with low optical losses. Two mechanical properties characteristic of elasticity and hardness of PT films are studied. The elastic modulus (E or Young's modulus) and the hardness (H) are measured by the nanoindentation technique. These mechanical properties are correlated to the crystalline quality of PT/MgO thin films. The films show epitaxial relationship with the MgO substrate and the orientation of crystallites perpendicularly to the surface substrate may be the consequence of a growth process along c-axis, a-axis or both. Differences on curves plotting hardness and elastic modulus as a function of indentation depth are observed as the curves are less dispersed for the films mainly c-axis oriented. 相似文献
16.
N.E. Stankova I.G. Dimitrov T.R. Stoyanchov P.A. Atanasov 《Applied Surface Science》2007,254(4):1268-1272
In this work the optical and the gas sensing properties of thick TiO2 waveguide films, produced by pulsed laser deposition, were investigated by m-line spectroscopy. The films were deposited on (0 0 1) SiO2 substrates at temperature of 100 °C. The thickness of the films was measured to be in the range from 650 to 1900 nm and the roughness increases from 5 to 14.6 nm. High quality mode spectra, consisted of thin and bright TE and TM modes, were observed in the films with thickness up to 1200 nm. All the films revealed anisotropic optical properties. Gas sensitivity of the films to CO2 was examined at room temperature on the basis of the variations of the refractive index. CO2 concentration of 3 × 104 ppm was detected, which corresponds to a refractive index variation of about 1 × 10−4. The crystal structure and the optical transmittance of the films were also presented and discussed. 相似文献
17.
Aivar Tarre Jaan Aarik Hugo Mndar Ahti Niilisk Rainer Prna Raul Rammula Teet Uustare Arnold Rosental Vino Sammelselg 《Applied Surface Science》2008,254(16):5149-5156
Atomic layer deposition of Cr2O3 thin films from CrO2Cl2 and CH3OH on amorphous SiO2 and crystalline Si(1 0 0) and -Al2O3() substrates was investigated, and properties of the films were ascertained. Self-limited growth with a rate of 0.05–0.1 nm/cycle was obtained at substrate temperatures of 330–420 °C. In this temperature range epitaxial eskolaite was formed on the -Al2O3() substrates. The predominant crystallographic orientation in the epitaxial films depended, however, on the growth temperature and film thickness. Sufficiently thick films grown on the SiO2 and Si(1 0 0) substrates contained also the eskolaite phase, but thinner films deposited at 330–375 °C on these substrates were amorphous. The growth rate data of films with different phase composition allowed a conclusion that the crystalline phase grew markedly faster than the amorphous phase did. The amorphous, polycrystalline and epitaxial films had densities of 4.9, 5.1 and 5.1–5.3 g/cm3, respectively. 相似文献
18.
S.H. Mohamed André Anders L. Galán 《Journal of Physics and Chemistry of Solids》2007,68(12):2227-2232
Thin films of tungsten oxynitrides were deposited on substrates preheated at 300 °C from metallic tungsten target using reactive pulsed d.c. magnetron sputtering. The deposition was carried out at different nitrogen to total reactive gas partial pressures ratios. The energy dispersive analysis of X-ray showed that significant incorporation of nitrogen occurred only when the nitrogen partial pressure exceeded 74% of the total reactive gas pressure. X-ray diffraction analysis revealed that the formation of a specific crystalline phase is affected by the composition and the possibility of competitive growth of different phases. The increase of nitrogen content into the films increases the optical absorption and decreases the optical band gap. The refractive index was determined from the transmittance spectra using Swanepoel's method. It was found that the refractive index increases with increasing nitrogen content over the entire spectral range. The values of the tungsten effective coordination number, Nc, was estimated from the analysis of the dispersion of the refractive index, and an increase in Nc with increasing nitrogen content was observed. 相似文献
19.
Effect of microstructure on the thermoelectric properties of CSD-grown Bi2Sr2Co2Oy thin films
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Three Bi2Sr2Co2Oy thin films with different microstructures have been prepared by chemical solution deposition on LaAlO 3(001) through varying the annealing temperature.With the decrease in the annealing temperature,both the size and c-axis alignment degree of grains in the film decrease as well,leading to an increase in the film resistivity.In addition,the decrease in the annealing temperature also results in a slight increase in the Seebeck coefficient due to the enhanced energy filtering effect of the small-grain film.The nanostructured Bi2Sr2Co2Oy film with an average grain size of about 100 nm shows a power factor comparable to that of films with larger grains.Since the thermal conductivity of the nanostructured films can be depressed due to the enhanced phonon scattering by grain boundary,a higher figure of merit is expected in Bi2Sr2Co2Oy thin film with grains in nanometer size. 相似文献
20.
We report novel pulsed laser deposition conditions that were used to obtain superconducting epitaxial YBCO thin films, grown in situ using an oxygen pressure lower than the usual one during the cool-down time. We studied the influence of the PLD conditions as substrate temperature, oxygen pressure, laser fluence, and number of laser pulses on the crystallographic and morphological features, and on the superconducting properties of the films. Good superconducting properties were obtained without a high temperature post-deposition annealing process. A maximum critical temperature of 88.6 K was obtained. 相似文献