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1.
A.Z. Simes M.A. Ramirez C.S. Riccardi E. Longo J.A. Varela 《Materials Characterization》2008,59(6):675-680
Thin films of SrBi4Ti4O15 (SBTi), a prototype of the Bi-layered-ferroelectric oxide family, were obtained by a soft chemical method and crystallized in a domestic microwave oven. For comparison, films were also crystallized in a conventional method at 700 °C for 2 h. Structural and morphological characterization of the SBTi thin films were investigated by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. Using platinum coated silicon substrates, the ferroelectric properties of the films were determined. Remanent polarization Pr and a coercive field Ec values of 5.1 μC/cm2 and 135 kV/cm for the film thermally treated in the microwave oven and 5.4 μC/cm2 and 85 kV/cm for the film thermally treated in conventional furnace were found. The films thermally treated in the conventional furnace exhibited excellent fatigue-free characteristics up to 1010 switching cycles indicating that SBTi thin films are a promising material for use in non-volatile memories. 相似文献
2.
Qi He Hui-bin Guo Jun-jun Wei S.J Askari Hong-bin Wang Shu-yu Zhang Hai Yang Xiao-ping Su Fan-xiu Lu 《Thin solid films》2008,516(15):4695-4699
HfO2 thin films with columnar microstructure were deposited directly on ZnS substrates by electron beam evaporation process. SiO2 thin films, deposited by reactive magnetron sputtering, were used as buffer layers, HfO2 thin films of granular microstructure were obtained on SiO2 interlayer by this process. X-ray diffraction patterns demonstrate that the as-deposited HfO2 films are in an amorphous-like state with small amount of crystalline phase while the HfO2 films annealed at 450 °C in O2 for 30 min and in Ar for 150 min underwent a phase transformation from amorphous-like to monoclinic phase. Antireflection effect in certain infrared wave band, such as 3–6 μm, 4–12 μm, 4–8 μm and 3–10 μm, can be observed, which was dependent on the thickness of thin films. The cross-sectional images of HfO2 films, obtained by field emission scanning electron microscopy, revealed that there was no distinct morphological change upon annealing. 相似文献
3.
Atmospheric pressure chemical vapour deposition of SnSe and SnSe2 thin films on glass 总被引:1,自引:0,他引:1
Nicolas D. Boscher Claire J. Carmalt Robert G. Palgrave Ivan P. Parkin 《Thin solid films》2008,516(15):4750-4757
Atmospheric pressure chemical vapour deposition of tin monoselenide and tin diselenide films on glass substrate was achieved by reaction of diethyl selenide with tin tetrachloride at 350–650 °C. X-ray diffraction showed that all the films were crystalline and matched the reported pattern for SnSe and/or SnSe2. Wavelength dispersive analysis by X-rays show a variable Sn:Se ratio from 1:1 to 1:2 depending on conditions. The deposition temperature, flow rates and position on the substrate determined whether mixed SnSe–SnSe2, pure SnSe or pure SnSe2 thin films could be obtained. SnSe films were obtained at 650 °C with a SnCl4 to Et2Se ratio greater than 10. The SnSe films were silver–black in appearance and adhesive. SnSe2 films were obtained at 600–650 °C they had a black appearance and were composed of 10 to 80 μm sized adherent crystals. Films of SnSe only 100 nm thick showed complete absorbtion at 300–1100 nm. 相似文献
4.
A. Abrutis M. Lukosius Z. Saltyte R. Galvelis P.K. Baumann M. Schumacher J. Lindner 《Thin solid films》2008,516(15):4758-4764
Metal-organic chemical vapour deposition (MOCVD) of various phases in PrOx system has been studied in relation with deposition temperature (450–750 °C) and oxygen partial pressure (0.027–100 Pa or 0.2–750 mTorr). Depositions were carried out by pulsed liquid injection MOCVD using Pr(thd)3 (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) precursor dissolved in toluene or monoglyme. By varying deposition temperature and oxygen partial pressure amorphous films or various crystalline PrOx phases (Pr2O3, Pr7O12, Pr6O11) and their mixtures can be grown. The pure crystalline Pr2O3 phase grows only in a narrow range of partial oxygen pressure and temperature, while high oxygen pressure (40–100 Pa) always leads to the most stable Pr6O11 phase. The influence of annealing under vacuum at 750 °C on film phase composition was also studied. Near 90% step coverage conformity was achieved for PrOx films on structured silicon substrates with aspect ratio 1:10. In air degradation of Pr2O3 films with transformation to Pr(OH)3 was observed in contrast to Pr6O11 films. 相似文献
5.
-Al2O3 prepared by combustion technique was ball-billed in a planetary mill in toluene medium at 300 rpm in ZrO2 pot with a ball to powder ratio 10:1 for 1, 5, 10, 15, and 20 hours. X-ray diffraction pattern from the milled materials showed super-Lorentzian peak shapes for -Al2O3 peak profiles. The super-Lorentzian peak shape has been attributed to the bimodal size distribution of the -Al2O3 particles. Rietveld analysis using two different phase fractions of -Al2O3 with different microstructural features yielded a low goodness-of-fit of the x-ray data indicating the suitability of the assumed model. The phase fraction of -Al2O3 particles with smaller size increases with the milling time. Further the particles shapes were observed to be cylindrical in this case with the cylinder axis along the crystallographic c-axis. The cylinder diameter and the length were obtained to be 86 and 140 respectively after 20 hrs of milling. The -Al2O3 particles of larger size are isotropic. It is, thus, proposed that milling induces bimodal size distribution in the initial hours of milling. 相似文献
6.
Edward G. Rakov Igor G. Ivanov Sergey N. Blinov Nikolai V. Kazakov Valery V. Skudin Nikolai G. Digurov Anna K. Bogdanovich 《Fullerenes, Nanotubes and Carbon Nanostructures》2005,12(1):29-32
By method of isothermal gravimetry at 600-700°C, CH4 concentration 32-100% in Ar and 91-100% in H2 under atmospheric pressure the kinetics of CH4 pyrolysis under Ni/La2O3 catalysts is studied. Estimated apparent activation energy of reaction is 73 kJ/mol for fresh catalyst and 71 kJ/mol for aged one. The reaction order on CH4 changes from 1.05 at 600°C to 1.3 at 700°C. The influence of H2 concentration on the reaction rate is more complicated. On the basis of kinetics measurements continuously working laboratory-scale reactor with gas and catalyst counter-flow is constructed and tested. 相似文献
7.
A series of 0.2–0.6 μm thick SnOx films were deposited onto borosilicate and sodalime silica glass substrates by atmospheric plasma discharge chemical vapor deposition at 80 °C. SnOx films deposited from monobutyltin trichloride contained a large percentage of SnCl2:2H2O, and therefore were partially soluble in water. SnOx coatings deposited from tetrabutyltin were not soluble in water or organic solvents, had good adhesion even at growth rates as high as 2.3 nm/s, had high transparency of 90% and electrical resistivity of 107 Ω cm. As-grown tin oxide coatings were amorphous with a small concentration of SnO2, SnO and Sn crystalline phases as determined by grazing angle X-ray diffraction and X-ray photoelectron spectroscopy measurements. Upon annealing in air at 600 °C the resistivity of SnOx films decreased to 5–7 Ω cm. Furthermore, optical and X-ray measurements indicated that SnOx was converted into SnO2 (cassiterite) with a direct band gap of 3.66 eV. Annealing of as-grown SnOx films in vacuum at 340 °C led to formation of the p-type conductor SnO/SnOx. The indirect band gap of SnO was calculated from the optical spectra to be 0.3 eV. 相似文献
8.
Annealing effects on microstructure and mechanical properties of chromium oxide coatings 总被引:1,自引:0,他引:1
Xiaolu Pang Kewei Gao Fei Luo Huisheng Yang Lijie Qiao Yanbin Wang Alex A. Volinsky 《Thin solid films》2008,516(15):4685-4689
Reactive radio frequency magnetron sputter-deposited chromium oxide coatings were annealed at different temperatures and times. The influence of annealing temperature on the microstructure, surface morphology and mechanical properties was examined by X-ray diffraction, nanoindentation, pin-on-disc wear and scratch tests, respectively. X-ray results show that the chromium oxide sputtered at room temperature in low oxygen flux is primarily amorphous. Annealing below 400 °C did not cause much change, while annealing at higher temperature of 500 °C caused a significant change in microstructure and mechanical properties. Hardness increased from 12.3 GPa to 26 GPa, and the wearability improved with higher annealing temperature due to the formation of crystalline Cr2O3 phase, which occurs at 470 °C. Annealing time had little effect on mechanical properties and microstructure, although coating surface roughness increased with a longer annealing time. Coating adhesion was improved by annealing, due to residual stress relief and possible interfacial interdiffusion. 相似文献
9.
N. Kobayashi H. Katsumata H. L. Shen M. Hasegawa Y. Makita H. Shibata S. Kimura A. Obara S. Uekusa T. Hatano 《Thin solid films》1995,270(1-2):406-410
Structural and optical properties have been investigated for surface β-FeSi2 layers on Si(100) and Si(111) formed by ion beam synthesis using 56Fe ion implantations with three different energies (140–50 keV) and subsequent two-step annealing at 600 °C and up to 915 °C. Rutherford backscattering spectrometry analyses have revealed Fe redistribution in the samples after the annealing procedure, which resulting in a Fe-deficient composition in the formed layers. X-ray diffraction experiments confirmed the existence of /gb-FeSi2 by annealing up to 915 °C, whereas the phase transformation from the β to phase has been induced at 930 °C. In photoluminescence measurements at 2 K, both β-FeSi2/Si(100) and β-FeSi2/Si(111) samples, after annealing at 900–915 °C for 2 h, have shown two dominant emissions peaked around 0.836 eV and 0.80 eV, which nearly coincided with previously reported PL emissions from the sample prepared by electron beam deposition. Another β-FeSi2/Si(100) sample has shown sharp emissions peaked at 0.873 eV and 0.807 eV. Optical absorption measurements at room temperature have revealed the allowed direct bandgap of 0.868–0.885 eV as well as an absorption coefficient of the order of 104 cm−1 near the absorption edge for all samples. 相似文献
10.
(100)-oriented 0.462Pb(Zn1/3Nb2/3)O3–0.308Pb(Mg1/3Nb2/3)O3–0.23PbTiO3 (PZN-PMN-PT) perovskite ferroelectric thin films were prepared on La0.7Sr0.3MnO3/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, 2Pr, 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. 相似文献
11.
Electron beam evaporation was used to produce Nb/Cu and Cu/Nb bilayers on silicon. The phase sequence and morphology were investigated as a function of annealing temperature in the temperature range between 200 °C and 800 °C, using Auger electron spectroscopy, Rutherford backscattering spectrometry, X-ray diffraction, and transmission electron microscopy. Independently of the sequence of deposition, the phases Nb3Si and Nb5Si3 are the two first niobium phases to be formed as a very thin layer at the Nb---Si interface. However, there is evidence that the reaction between niobium and silicon depends strongly on the presence of copper at the Nb---Si interface. The unusual coexistence of Nb5Si3, NbSi2 and niobium phases was also observed. The formation of the ternary phase Nb5Cu4Si4 was detected after annealing Cu/Nb at 700 °C and Nb/Cu at 800 °C. In the latter case the NbSi2 and Cu3Si+Cu4Si phases were formed through a layered growth process. 相似文献
12.
《Materials and Manufacturing Processes》2007,22(6):710-714
The effect of SiO2 addition on densification and grain-growth behavior of 8YSCZ/SiO2 composites was investigated using high purity 8 mol% yttria-stabilized cubic zirconia powders (8YSCZ) doped with 0, 1, 5, 10 wt% SiO2. The specimens were sintered at 1400°C for 1 hour. It was seen that the sintered density increased with SiO2 content up to 1 wt% and further increase in SiO2 content led to a decrease in density. The enhanced density with increasing SiO2 content up to 1 wt% could be mainly attributable to liquid phase sintering. For grain growth measurements, the specimens sintered at 1400°C were annealed at 1400, 1500, and 1600°C for 10, 50, and 100 hours. The experimental results showed that the grain growth in 8YSCZ/SiO2 composites occurred more slowly than that in undoped 8YSCZ. Also, the grain growth rate decreased with increasing SiO2 content. The grain growth exponent value and the activation energy for undoped 8YSCZ were found to be 2 and 289 kJ/mol, respectively. The addition of SiO2 raised the grain growth exponent value to 3, and activation energy for the grain growth process was increased from 289 to 420 kJ/mol for the addition of SiO2 from 0 to 10 wt%. 相似文献
13.
Polycrystalline AlN films with preferential orientation by plasma enhanced chemical vapor deposition
G. Snchez A. Wu P. Tristant C. Tixier B. Soulestin J. Desmaison A. Bologna Alles 《Thin solid films》2008,516(15):4868-4875
AlN thin films for acoustic wave devices were prepared by Microwave Plasma Enhanced Chemical Vapor Deposition under different process conditions, employing Si (100) and Pt (111)/SiO2/Si (100) substrates. The films were characterized by X-ray diffraction, Fourier transform infrared transmission spectroscopy, atomic force microscopy, scanning electron microscopy, and transmission electron microscopy. The values of the distance between the plasma and the tri-methyl-aluminum precursor injector, the radiofrequency bias potential, and the substrate temperature were central in the development of polycrystalline films. The choice of the chamber total pressure during deposition allowed for the development of two different crystallographic orientations, i.e., <0001> or <1010>. The film microstructures exhibited in general a column-like growth with rounded tops, an average grain size of about 40 nm, and a surface roughness lower than 20 nm under the best conditions. 相似文献
14.
V. Kuzucu M. Aksoy M.H. Korkut M.M. Yildirim 《Materials Science and Engineering: A》1997,230(1-2):75-80
The effect of different amounts of Nb and of homogenization on the ferritic stainless steels containing 17–18 wt.% Cr was investigated with scanning electron microscopy (SEM), optical microscopy, energy-dispersive spectrometry (EDS), X-ray diffraction (XRD) and differential thermal analysis (DTA). It was observed that M23C6, NbC and sigma phase formed in these steels. In addition, the formation of Nb2C was observed in the sample containing 3.0 wt.% Nb. While the amount of Nb increased from 0.5 to 3.0 wt.% Nb, the microhardness of the matrix and the amount of M23C6 decreased and the toughness of the samples increased. After homogenization, the increase in the toughness of the samples containing 1.5–3.0 wt.%Nb was considerable and impressive. 相似文献
15.
M. Ben Ali F. Bessueille J.M. Chovelon A. Abdelghani N. Jaffrezic-Renault M.A. Maaref C. Martelet 《Materials science & engineering. C, Materials for biological applications》2008,28(5-6):628-632
A mono-functional silane reagent, 3-mercaptopropyltrimethoxysilane (MPS) was used to modify the surface of silicon wafers. The structure of the SAMs formed with the MPS was investigated by contact angle measurements, ellipsometry, AFM, and X-ray photoelectron spectroscopy (XPS). The deposition of a metallic gold layer via ultra-high vacuum (UHV) evaporation reveals good adhesion properties on Au/MPS/SiO2/Si structure. The “chemisorption” between the SAM and the gold evaporated layer is confirmed by adhesion tests and optimum curing treatment is found 1 h at 100 °C). This very simple methodology, avoiding the usage of Cr and other metals as undercoating layers and could be proposed further for (bio)sensors applications. 相似文献
16.
Vaidyanathan Subramanian Nicholas Ndiege E.G. Seebauer Mark A. Shannon Richard I. Masel 《Thin solid films》2008,516(15):4784-4792
Micron thick tantalum pentoxide (Ta2O5) films have been proposed as thermal insulating layers in microchemical systems, but so far it has been difficult to deposit thick enough films over complex substrates. So far sol–gel films cracked upon heating whenever the film thicknesses were above 350 nm. A 350 nm thick film is too thin for effective insulation. Other techniques are not suitable for coating the complex structures associated with microchemical systems. In this paper we report sol–gel synthesis of 1.6 μm thick tantalum pentoxide (Ta2O5) films. The films are almost crack free, and adhere to silicon surfaces even upon flashing to 900 °C. The key to the synthesis is the addition of Polyvinylpyrrolidine (PVP) to the sol. Films grown in the absence of PVP all show cracks upon calcination to 900 °C while few cracks are seen with PVP. X-ray diffraction and Fourier transform infra red analysis show that orthorhombic Ta2O5 is formed in all cases. X-ray photoelectron spectroscopy shows the O:Ta ratio to be 2.8:1. This shows that sol–gel is a viable process for making the micron thick films of Ta2O5 needed as insulators for microchemical systems. 相似文献
17.
The deposition behavior of silicon in hot wire chemical vapor deposition was investigated, focusing on the generation of negatively charged species in the gas phase using a gas mixture of 20% SiH4 and 80% H2 at a 450 °C substrate temperature under a working pressure of 66.7 Pa. A negative current of 6–21 µA/cm2 was measured on the substrate at all processing conditions, and its absolute value increased with increasing wire temperature in the range of 1400 °C–1900 °C. The surface roughness of the films deposited on the silicon wafers increased with increasing wire temperature in the range of 1510 °C–1800 °C. The film growth rate on the positively biased substrates (+ 100 V, + 200 V) was higher than that on the neutral (0 V) and negatively biased substrates (− 100 V, − 200 V, − 300 V). These results indicate that the negatively charged species are generated in the gas phase and contribute to deposition. The surface roughness evolved during deposition was attributed to the electrostatic interaction between these negatively charged species and the negatively charged growing surface. 相似文献
18.
A highly oriented FeO thin film was formed from a Fe3O4 thin film containing Fe nanocrystallines by post-annealing at 600°C. Fe3O4 thin films were grown on Si(100) substrates by ion beam sputter deposition under oxygen ambient. The stoichiometry of the iron oxide thin film could be precisely controlled by in situ X-ray photoelectron spectroscopy (XPS). X-ray diffraction (XRD) pattern of the Fe3O4 thin film grown at substrate temperature of 300°C showed a mixed phase of Fe3O4 and Fe nanocrystallines with a preferred orientation (110). However, the mixed phase was converted to a highly oriented FeO(200) phase by post-annealing at 600°C. This could be inverted as a result of Ostwald ripening of the Fe3O4 and Fe nanocrystallines. 相似文献
19.
Y2.9Ce0.1Fe5-xCrxO12 (x = 0-0.5) nanoparticles were fabricated by a sol-gel method. Samples with particle size ranging from 60 to 64 nm were obtained and their crystalline structures and magnetic properties were investigated by X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). Results of VSM show that the saturation magnetization is increased firstly, after decreased with the Cr concentration (x). The saturation magnetization is increased with increasing the particle size. 相似文献
20.
A niobium-based alloy with 20% V–15% Al (at.%) was synthesized by mechanical alloying of elemental powders. During milling, the splitting of Nb X-ray peaks into two components was observed. Each component was found to correspond to a niobium solid solution (NbI and NbII) with a different lattice parameter. The intensities of NbI peaks on X-ray diffraction patterns decreased with the milling time and disappeared completely after 180 h of milling while the intensities of NbII peaks gradually increased. The powders were hot pressed and microstructural and phase analyses of the consolidated material were carried out. The microstructure consisted of Nb solid solution, Nb3Al-base intermetallic with the A15 crystal structure and dispersoid Al2O3. Also an unexpected, detrimental, Nb2Al-base σ phase was found. The volume fraction of the σ phase depended on the temperature of consolidation. 相似文献