共查询到20条相似文献,搜索用时 31 毫秒
1.
Thin films of the aluminum oxide (Al 2O 3)–titanium oxide (TiO 2) system including Al 2O 3, TiO 2, and Al 2O 3/TiO 2 were prepared by radio-frequency (r.f.) magnetron sputtering using ceramic targets of Al 2O 3, TiO 2, and Al 2O 3/TiO 2 composites with different Al 2O 3/TiO 2 ratio. These films were studied at different substrate temperatures, r.f. powers, and annealing temperatures. Composition, microstructure, thermomechanical property of internal stress, and mechanical property of scratch adhesion, were evaluated. A thin film with a dielectric constant of 62 and a loss tangent of 0.012 was obtained at 500 °C from a 10/90 target. This thin film remained the high dielectric constant of TiO 2, but had an improvement in the dielectric loss tangent. Al 2O 3-containing films had a higher resistivity and breakdown field, which was improved further by annealing. Optical properties, such as refractive index and optical transmittance, were also investigated. 相似文献
2.
Samarium-doped ceria (SDC) thin films were prepared from Sm(DPM) 3 (DPM = 2,2,6,6-tetramethyl-3,5-heptanedionato) and Ce(DPM) 4 using the aerosol-assisted metal–organic chemical vapor deposition method. -Al 2O 3 and NiO-YSZ (YSZ = Y 2O 3-stabilized ZrO 2) disks were chosen as substrates in order to investigate the difference in the growth process on the two substrates. Single cubic structure could be obtained on either -Al 2O 3 or NiO-YSZ substrates at deposition temperatures above 450 °C; the similar structure between YSZ and SDC results in matching growth compared with the deposition on -Al 2O 3 substrate. A typical columnar structure could be obtained at 650 °C on -Al 2O 3 substrate and a more uniform surface was produced on NiO-YSZ substrate at 500 °C. The composition of SDC film deposited at 450 °C is close to that of precursor solution (Sm : Ce = 1 : 4), higher or lower deposition temperature will both lead to sharp deviation from this elemental ratio. The different thermal properties of Sm(DPM) 3 and Ce(DPM) 4 may be the key reason for the variation in composition with the increase of deposition temperature. 相似文献
3.
Highly oriented aluminum nitride thin films were grown on sapphire (0001)-substrate by pulsed laser deposition technique. Characterization was done by X-ray-diffraction, elastic recoil detection analysis and Rutherford backscattering/channeling measurements. The epitaxial properties were studied as function of the substrate temperature and the deposition rate. An epitaxial relation to the sapphire substrate is found to be AlN [0001] || Al 2O 3 [0001] and AlN [11
0] || Al 2O 3 [10
0]. XRD-texture-analysis on films deposited at 850°C shows a full width half maximum Δω of 0.13° (rocking curve) and Δ of 1.1° (in-plane). 相似文献
4.
1 mol%Er 3+–10 mol%Yb 3+ codoped Al 2O 3 thin films have been prepared on thermally oxidized SiO 2/Si(110) substrates by a dip-coating process in the non-aqueous sol–gel method from the hydrolysis of aluminum isopropoxide [Al(OC 3H 7) 3] under isopropanol environment. Addition of N, N-dimethylformamide (DMF) as a drying control chemical additive (DCCA) into the sol suppresses formation of the cracks in the Er 3+–Yb 3+ codoped Al 2O 3 thin films when the rare-earth ion is doped with a high doping concentration. Homogeneous, smooth and crack-free Er 3+–Yb 3+ codoped Al 2O 3 thin films form at the conditions by a molar ratio of 1:1 for DMF:Al(OC 3H 7) 3. A strong photoluminescence spectrum with a broadband extending from 1.400 to 1.700 µm centered at 1.533 µm is obtained for the Er 3+–Yb 3+ codoped Al 2O 3 thin films, which is unrelated to the addition of DMF. Controllable formation of the Er 3+–Yb 3+ codoped Al 2O 3 thin films may be explained by the fact that the DMF assisted the deprotonation process of Al–OH at the surfaces of gel particles, resulting in enhancement of the degree of polymerization of sols and improvement of the mechanical properties of gel thin films. 相似文献
5.
Calcium oxide and calcium hafnium oxide thin films were grown by atomic layer deposition on borosilicate glass and silicon substrates in the temperature range of 205–300 °C. The calcium oxide films were grown from novel calcium cyclopentadienyl precursor and water. Calcium oxide films possessed refractive index 1.75–1.80. Calcium oxide films grown without Al 2O 3 capping layer occurred hygroscopic and converted to Ca(OH) 2 after exposure to air. As-deposited CaO films were (200)-oriented. CaO covered with Al 2O 3 capping layers contained relatively low amounts of hydrogen and re-oriented into (111) direction upon annealing at 900 °C. In order to examine the application of CaO in high-permittivity dielectric layers, mixtures of Ca and Hf oxides were grown by alternate CaO and HfO 2 growth cycles at 230 and 300 °C. HfCl 4 was used as a hafnium precursor. When grown at 230 °C, the films were amorphous with equal amounts of Ca and Hf constituents (15 at.%). These films crystallized upon annealing at 750 °C, showing X-ray diffraction peaks characteristic of hafnium-rich phases such as Ca 2Hf 7O 16 or Ca 6Hf 19O 44. At 300 °C, the relative Ca content remained below 8 at.%. The crystallized phase well matched with rhombohedral Ca 2Hf 7O 16. The dielectric films grown on Si(100) substrates possessed effective permittivity values in the range of 12.8–14.2. 相似文献
6.
Thin films of the system xAl 2O 3–(100 − x)Ta 2O 5–1Er 2O 3 were prepared by a sol–gel method and a dip-coating technique. The influences of the composition and the crystallization of the films on Er 3+ optical properties were investigated. Results of X-ray diffraction indicated that the crystallization temperature of Ta 2O 5 increased from 800 to 1000 °C with increased values of x. In crystallized films, the intensities of the visible fluorescence and upconversion fluorescence tend to decrease with an increase in x values, due to the high phonon energy of Al 2O 3; the strongest fluorescence is observed in a crystallized film for x = 4 heat treated at 1000 °C. In amorphous films obtained by heat treatment at relatively low temperatures the Er 3+ fluorescence could not be observed because strong fluorescence from organic residues remaining in the films thoroughly covered the Er 3+ fluorescence. On the other hand, the Er 3+ upconversion fluorescence in the amorphous films was observed to be stronger than that in the crystallized films. The strongest upconversion fluorescence is observed in an amorphous film for x = 75 heat treated at 800 °C. 相似文献
7.
An effective method is developed for low temperature metal oxide deposition through thermal decomposition of metal diketonates in supercritical carbon dioxide (scCO 2) solvent. The rates of Al(acac) 3 (Aluminum acetyl acetonate) and Ga(acac) 3 (Gallium acetyl acetonate) thermal decomposition in scCO 2 to form conformal Al 2O 3 and Ga 2O 3 thin films on planar surfaces were investigated. The thermal decomposition reaction of Al(acac) 3 and Ga(acac) 3 was found to be initialized at 150 °C and 160 °C respectively in scCO 2 solvent, compared to 250 °C and 360 °C in analogous vacuum-based processes. By measuring the temperature dependence of the growth rates of metal oxide thin films, the apparent activation energy for the thermal decomposition of Al(acac) 3 in scCO 2 is found to be 68 ± 6 kJ/mol, in comparison with 80–100 kJ/mol observed for the corresponding vacuum-based thermal decomposition reaction. The enhanced thermal decomposition rate in scCO 2 is ascribed to the high density solvent which effectively reduces the energy of the polar transition states in the reaction pathway. Preliminary results of thin film deposition of other metal oxides including ZrO x, FeO x, Co 2O 3, Cr 2O 3, HfO x from thermal decomposition of metal diketonates or fluorinated diketonates in scCO 2 are also presented. 相似文献
8.
In this study, we have investigated different methods for preparation of thin films of C 60 and C 70-sulfur compounds. Films of good quality were obtained by reaction of amorphous C 60 and C 70 films with a saturated sulfur solution in toluene at 40°C or with saturated sulfur vapour at a temperature of 140°C for several hours. The quality of the fullerene-sulfur films were strongly dependent on the microstructure of the initially deposited fullerene film and the synthesis temperature. X-ray diffraction analyses showed that both methods lead to the formation of films consisting of C 60S 16 and C 70S 48 (space groups C 2/c and Amm2, respectively). C 60S 16 films synthesised on Al 2O 3(012) and Si(100) substrates were texture-free while C 70S 48 films typically exhibited a preferential (100) orientation. The films were also characterised by Raman and IR- spectroscopy, which confirmed that the interactions between the fullerene molecules and the S 8 rings are weak. The fullerene-sulfur compounds were found to be unstable at high vacuum conditions. Both materials C 60S 16 and C 70S 48 are non-conductive at room temperature with conductivities less then 10 −5 (Ω/cm). 相似文献
9.
SrTiO 3 thin films were prepared by aerosol metal-organic chemical vapour deposition on (001) MgO, R-plane Al 2O 3 and (001) Si single-crystal substrates. Strontium tetramethyl heptadionate and titanium n-butoxide dissolved in diethyleneglycol dimethyl ether were used as precursors. The structure of the films was investigated by X-ray diffraction and transmission electron microscopy. Epitaxial films with [001] and [111] orientation perpendicular to the substrate surface were obtained on MgO and Al 2O 3, respectively. The epitaxial films on the MgO substrate were found to be in a relaxed state with lattice parameters corresponding to the bulk values. SrTiO 3 films on the Si substrate were grown as highly textured in the [011]direction and randomly oriented in the plane parrallel to the substrate surface. 相似文献
10.
We have studied the surface termination of ZnO(0001¯) films grown on Al 2O 3 substrates with high epitaxial quality. The structural properties of the ZnO films were investigated by X-ray scattering, revealing a predominant (0001¯)ZnO out-of-plane texture with the [112¯0] ZnO[0001] Al2O3 and [112¯0] ZnO[101¯0] Al2O3 azimuthal orientations for (112¯0)Al 2O 3 and(0001)Al 2O 3 substrates, respectively. The surface termination was determined by X-ray photoemission spectroscopy (XPS) via pyridine (C 5H 5N) adsorption at the ZnO surface. XPS data recorded at different temperatures after exposure to pyridine revealed that for both orientations of the Al 2O 3 substrates the deposited ZnO films were terminated by oxygen atoms, i.e. corresponding to a ZnO (0001¯) surface. 相似文献
11.
Spectrally selective Ni-Al 2O 3 composite films were prepared by r.f. planar magnetron sputtering using hot-pressed targets of two different compositions. The composition of the films were varied by co-sputtering the target with additional nickel pellets distributed uniformly on the target. The composition of the films were analysed by energy-dispersive X-ray analysis. Optical simulations were carried out with the experimentally measured n and k and the published n and k of the metallic substrate. R.f.-sputtered SiO 2 and Al 2O 3 were used as antireflection coatings. From the computer optimization studies we found that = 0.94 and (100°C) = 0.07 could be obtained with 650 Å of Ni-Al 2O 3 ( f = 0.61) antireflected with 780 Å SiO 2 on a nickel-coated glass substrate. When molybdenum-coated nickel-plated stainless steel substrates were used, the films were found to be stable up to 500°C in air. 相似文献
12.
The main objective of this study was to investigate the formation of thaumasite in carbonated Portland cement mortars. Another important purpose was to study the role that ettringite (AFt) plays in the process of formation of Th and its influence in the deterioration of the mortars. Work was carried out with mortar prisms, elaborated using two different cements: one of them with low Al2O3 content (exempt of C3A) and the other one with high Al2O3 content. Additions of different amounts of gypsum and/or calcium carbonate were also done. After three months of curing at 21 °C and 100% RH mortars were submitted to an accelerated carbonation process until total transformation of Ca(OH)2 into CaCO3. Then mortar prisms were partially immersed in distilled water and kept at temperature ranging from 0 to 5 °C for one year. A mineralogical, micro-structural and physical characterisation was carried out on samples at different ages. The thaumasite formation rate was much lower in those mortars elaborated with the cement exempt of C3A than in those mortars made with the cement having high proportion of C3A when they are conserved in water. The study of transversal sections of prisms reveals the presence of a white expansive product (thaumasite) not always homogeneously distributed. 相似文献
13.
The Al 2O 3 particles are introduced into the Al-4wt.%Mg melt by the “vortex” method. After being cast, Al 2O 3-(Al-4wt.%Mg) composites are remelted at 700, 750, 800 and 850°C for different residence times to investigate the formation of MgAl 2O 4 (spinel). The results show that MgAl2O4 is the unique interface of the Al2O3-(Al---Mg) composites held at 700–850°C. Fine MgAl2O4 crystals grow on the surface of the Al2O3 particle but, as the holding temperature and the residence time increase, some spinels will form themselves into pyramidal shape. The MgAl2O4 grows not only at the matrix-particle interface but also on the surface of the composite specimens. The formation reactions of interfacial MgAl2O4 are as follows: Mg(1) + 2Al(1) + 2O2(g) = MgAl2O4(s)3Mg(1) + 4Al2O3(s) = 3MgAl2O4(s) + 2Al(1) Both of them are equally important. 相似文献
14.
Conductive RuO 2 thin films were epitaxially grown on LaAlO 3(100) and MgO(100) substrates by metal-organic chemical vapor deposition (MOCVD). The deposited RuO 2 films were crack-free, and well adhered to the substrates. The RuO 2 film is (200) oriented on LaAlO 3 (100) substrates at deposition temperature of 600°C and (110) oriented on MgO(100) substrates at deposition temperature of 350°C and above. The epitaxial growth of RuO 2 on MgO and LaAlO 3 is demonstrated by strong in-plane orientation of thin films with respect to the major axes of the substrates. The RuO 2 films on MgO(100) contain two variants and form an orientation relationship with MgO given by RuO 2(110)//MgO(100) and RuO 2[001]//MgO[011]. The RuO 2 films on LaAlO 3(100), on the other hand, contain four variants and form an orientation relationship with LaAlO 3 given by RuO 2(200)//LaAlO 3(100) and RuO 2[011]//LaAlO 3[011]. Electrical measurements on the RuO 2 thin films deposited at 600°C show room-temperature resistivities of 40 and 50 μΩ cm for the films deposited on the MgO and LaAlO 3 substrates, respectively. 相似文献
15.
利用Al和TiO 2之间的放热化学反应, 采用激光原位合成技术在TC4钛合金基体材料表面制备了Al 2O 3/Ti-Al金属间化合物基复合涂层。对比分析了激光功率、激光束扫描速度和光斑尺寸变化对激光能量密度变化量的影响程度, 借助X射线衍射仪(XRD)、光学显微镜(OM)、能谱仪(EDS)和显微硬度计分别考察了激光束扫描速度对复合涂层表面宏观形貌、截面显微组织结构和显微硬度的影响。结果显示, 扫描速度的变化对激光能量密度变化量的影响程度最大, 光斑尺寸次之, 激光功率的变化影响最弱。随着激光束扫描速度的增大, 复合涂层表面渐趋粗糙, “鱼鳞纹”状形貌特征趋于明显, 复合涂层与基材结合区厚度减小。激光原位复合涂层主要由k-Al 2O 3和α-Al 2O 3增强相与α-Ti和α 2-Ti 3Al基体相组成。随着激光束扫描速度增大, 复合涂层内k-Al 2O 3部分转变为α-Al 2O 3, Al 2O 3增强相有由枝晶状向纤维状转变的趋势; 复合涂层截面显微硬度自基体至涂层表面过度平缓, 且涂层区显微硬度分布均匀, 明显高于基材平均显微硬度。 相似文献
16.
采用原位聚合与热亚胺化的方法,成功制备了一系列不同纳米Al_2O_3粒子质量分数的纳米Al_2O_3/聚酰亚胺(PI)复合薄膜。通过SEM、TEM、XRD、FTIR、LCR数字电桥、高压电源及电子万能材料试验机对纳米Al_2O_3/PI复合薄膜的微观结构、介电性能及力学性能进行了表征和测试。结果表明:纳米Al_2O_3粒子在均匀地分散在PI基体中;当纳米Al_2O_3粒子质量分数为8%时,纳米Al_2O_3/PI复合薄膜的击穿强度和拉伸强度均达到了最大值;纳米Al_2O_3/PI复合薄膜的介电常数随纳米Al_2O_3质量分数的增加而增加。 相似文献
17.
Thin tantalum oxide films were deposited using atomic layer deposition from TaCl 5 and H 2O at temperatures in the range 80–500 °C. The films deposited at temperatures below 300 °C were predominantly amorphous, whereas those grown at higher temperatures were polycrystalline containing the phases TaO 2 and Ta 2O 5. The oxygen to tantalum mass concentration ratio corresponded to that of TaO 2 at all growth temperatures. The optical band gap was close to 4.2 eV for amorphous films and ranged from 3.9 to 4.5 eV for polycrystalline films. The refractive index measured at λ = 550 nm increased from 1.97 to 2.20 with an increase in growth temperature from 80 to 300 °C. The films deposited at 80 °C showed low absorption with absorption coefficients of less than 100 cm −1 in the visible region. 相似文献
18.
Metal-organic chemical vapour deposition (MOCVD) of various phases in PrO x 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 PrO x phases (Pr 2O 3, Pr 7O 12, Pr 6O 11) and their mixtures can be grown. The pure crystalline Pr 2O 3 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 Pr 6O 11 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 PrO x films on structured silicon substrates with aspect ratio 1:10. In air degradation of Pr 2O 3 films with transformation to Pr(OH) 3 was observed in contrast to Pr 6O 11 films. 相似文献
19.
Pure and boron-doped γ-Al 2O 3 membranes have been synthesized by the sol–gel method. The thermal stability of the unsupported alumina membrane was studied by determining the pore structure (including average pore size, pore volume and BET surface area). The average pore size of the pure alumina membrane increased sharply after sintering at temperatures higher than 1000°C. Addition of 16% boron can considerably stabilize the pore structure of the unsupported alumina membrane. The pore diameter for the B-doped membrane was stabilized within 13 nm after sintering at 1200°C for 5 h. The substantial increase in the pore size for the pure alumina membrane at the sintering temperature of 1000–1200°C was accompanied by the phase transformation from γ-Al 2O 3 to -Al 2O 3. The addition of boron can raise the temperature of this phase transformation significantly and, thus, improves the thermal stability of the membranes. 相似文献
20.
为更好地实现口腔修复体的美学修复效果,采用掺杂不同含量Fe 2O 3(0.01wt%~0.09wt%)和Al 2O 3(0.1wt%)的3 mol% Y 2O 3稳定的ZrO 2(3Y-TZP)粉体为原料,经过铺粉、压制、烧结等工艺制得色度渐变的多层陶瓷结构Al 2O 3-Fe 2O 3/3Y-TZP梯度复合陶瓷。对该梯度复合陶瓷的色度分布、烧结性能和力学性能进行检测,同时研究了Fe 2O 3和Al 2O 3的掺杂对3Y-TZP陶瓷组织和性能的影响。结果表明,制得的Al 2O 3-Fe 2O 3/3Y-TZP梯度复合陶瓷色度由红黄向白色沿成分变化方向呈梯度变化,与天然牙齿色度分布规律一致;力学性能呈梯度变化并从无色端到有色端逐渐降低,但仍满足牙科使用需求(≥ 800 MPa);在无色瓷层中掺杂微量Al 2O 3(0.1wt%)可以改善Al 2O 3-Fe 2O 3/3Y-TZP梯度复合陶瓷的烧结性能,避免在预烧结过程中发生开裂。微量Fe 2O 3和Al 2O 3的掺杂会促进其在烧结过程中的致密化及晶粒长大;微量Fe 2O 3(0.01wt%)和Al 2O 3(0.1wt%)的掺杂有助于提高3Y-TZP陶瓷的挠曲强度,然而随着Fe 2O 3掺杂量的继续增多(≤ 0.09wt%)挠曲强度降低。 相似文献
|