共查询到20条相似文献,搜索用时 0 毫秒
1.
Feby Jose Ramaseshan R. S. Dash Tripura Sundari S. Deepti Jain Ganesan V. Chandramohan P. Srinivasan M.P. A.K. Tyagi Baldev Raj 《Materials Chemistry and Physics》2011
TiN and Ti1−xAlxN thin films with different aluminum concentrations (x = 0.35, 0.40, 0.55, 0.64 and 0.81) were synthesized by reactive magnetron co-sputtering technique. The structure, surface morphology and optical properties were examined using Grazing Incidence X-ray Diffraction (GIXRD), Atomic Force Microscopy (AFM), Raman spectroscopy and spectroscopic ellipsometry, respectively. The structure of the films were found to be of rocksalt type (NaCl) for x = 0.0–0.64 and X-ray amorphous for x = 0.81. AFM topographies show continuous mound like structure for the films of x between 0.0 and 0.64, whereas the film with x = 0.81 showed smooth surface with fine grains. Micro-Raman spectroscopic studies indicate structural phase separation of AlN from TiAlN matrix for x > 0.40. Ti1−xAlxN has the tendency for decomposition with the increase of Al concentration whereas c-TiN and hcp-AlN are stable mostly. The optical studies carried out by spectroscopic ellipsometry measurements showed a change from metallic to insulating behavior with the increase in x. These films are found to be an insulator beyond x = 0.81. 相似文献
2.
The pseudo-binary TiO2-FeSbO4 system was investigated by means of thermogravimetric analysis below 1673 K in O2. Rutile-type solid solutions were synthesised at 1373 K in O2 by means of a solid state reaction between the two pure end members TiO2 (rutile) and FeSbO4 mixed in stoichiometric amounts. Thermal stability of the (Ti2xFe1−xSb1−x)O4 solid solution increases with rutile content; equimolar (Ti1.00Fe0.50Sb0.50)O4 solid solutions decompose at about 1673 K forming a TiO2-enriched solid solution and FeSbO4, that subsequently decomposes into Fe2O3 (hematite) and a volatile Sb oxide, probably Sb4O6. For compositions characterised by higher Ti content the decomposition temperature is higher than 1673 K. 相似文献
3.
Ramakanta Naik 《Thin solid films》2010,518(19):5437-5441
In this paper, we report results of the optical properties of thermally deposited As2 − xS3 − xSbx thin films with x = 0.02, 0.07, 0.1 and 0.15. We have characterized the deposited films by Fourier Transform Infrared, Raman and X-ray photoelectron spectroscopy (XPS). The relationship between the structural and optical properties and the compositional variation were investigated. It was found that the optical bandgap decreases with increase in Sb content. The XPS core level spectra show a decrease in As2S3 percentage with increase in Sb content. This is confirmed from the shifting of the Raman peak from AsS3 vibrational mode towards SbS3 vibrational mode. 相似文献
4.
X. Zhang 《Thin solid films》2009,518(5):1522-1526
A series of zirconium silicon nitride (Zr1−xSixN) thin films were grown on r-plane sapphire substrates using reactive RF magnetron co-sputtering of Zr and Si targets in a N2/Ar plasma. X-ray diffraction pole figure analysis, X-ray reflectivity, X-ray photoelectron spectroscopy (XPS), optical microscopy, and optical absorption spectroscopy were used to characterize the film stoichiometries and structures after growth at 200 °C and post-deposition annealing up to 1000 °C in ultra-high vacuum. The atomically clean r-plane sapphire substrates induce high quality (100) heteroepitaxy of ZrN films rather than the (111) orientation observed on steel and silicon substrates, but the addition of Si yields amorphous films at the 200 °C growth temperature. After the annealing treatment, films with Si content x < 0.15 have compressive stress and crystallize into a polycrystalline structure with (100) fiber texture. For x > 0.15, the films are amorphous and remain so even after ultra-high vacuum annealing at 1000 °C. XPS spectra indicate that the bonding changes from covalent to more ionic in character as Si―N bonds form instead of Zr―N bonds. X-ray reflectivity, atomic force microscopy (AFM) and optical microscopy data reveal that after post-deposition annealing the 100 nm thick films have an average roughness < 2 nm, except for Si content near x = 0.15 corresponding to where the film becomes amorphous rather than being polycrystalline. At this stoichiometry, evidence was found for regions of film delamination and hillock formation, which is presumably driven by strain at the interface between the film and sapphire substrate. UV-visible absorption spectra also were found to depend on the film stoichiometry. For the amorphous Si-rich films (x > 0.15), the optical band gap increases with Si content, whereas for Zr-rich films (x < 0.15), there is no band gap and the films are highly conductive. 相似文献
5.
G. Greczynski J. LuM. Johansson J. JensenI. Petrov J.E. Greene L. Hultman 《Vacuum》2012,86(8):1036-1040
We demonstrate, for the first time, the growth of metastable single-phase NaCl-structure high-AlN-content Ti1−xAlxN alloys (x ≤ 0.64) which simultaneously possess high hardness and low residual stress. The films are grown using a hybrid approach combining high-power pulsed magnetron (HPPMS/HIPIMS) and dc magnetron sputtering of opposing metal targets. With HIPIMS applied to the Al target, Aln+ ion irradiation (dominated by Aln+) of the growing film results in alloys 0.55 ≤ x ≤ 0.60 which exhibit hardness H ∼ 30 GPa and low stress σ = 0.2-0.7 GPa, tensile. In sharp contrast, films with corresponding AlN concentrations grown with HIPIMS applied to the Ti target, giving rise to Tin+ ion irradiation (with a significant Ti2+ component), are two-phase - cubic (Ti,Al)N and hexagonal AlN - with low hardness, H = 18-19 GPa, and high compressive stress ranging up to 2.7 GPa. Annealing alloys grown with HIPIMS applied to the Al target results in age hardening due to spinodal decomposition; the hardness of Ti0.41Al0.59N increases from 30 to 33 GPa following a 900 °C anneal. 相似文献
6.
In this article, we report our studies on the relaxor behavior of Ba(Ti1−xHfx)O3 ceramics, made with close compositions between 0.20 ≤ x ≤ 0.30, to locate the hafnium concentration boundary for the normal to relaxor crossover. X-ray diffraction followed by Rietveld refinement shows the occurrence of single-phase cubic structure for the synthesized Ba(Ti1−xHfx)O3 ceramics. Temperature and frequency dependence of the real (?′) and imaginary (?″) parts of the dielectric permittivity has been studied in the temperature range of 90-350 K at frequencies of 0.1, 1, 10, and 100 kHz. A diffuse phase transition accompanying frequency dispersion is observed in the permittivity versus temperature plots revealing the occurrence of relaxor ferroelectric behavior. The Tm verses Hf concentration plot shows a discontinuous jump and change in the slope at x = 0.23. Quantitative characterization based on phenomenological models has also been presented. The plausible mechanism of the relaxor behavior has been discussed. Substitution of Hf4+ for Ti4+ in BaTiO3 reduces the long-range polar ordering yielding a diffuse ferroelectric phase transition. 相似文献
7.
S. Gautam P. Thakur P. Bazylewski R. Bauer A.P. Singh J.Y. Kim M. Subramanian R. Jayavel K. Asokan K.H. Chae G.S. Chang 《Materials Chemistry and Physics》2013
Dilute magnetic semiconductors are widely studied due to their potential applications in spin-resolved electronics. We report the direct evidences of intrinsic ferromagnetism in the primarily ferromagnetic ZnO:Co thin films using near-edge X-ray absorption fine structure (NEXAFS) and soft X-ray magnetic circular dichroism (XMCD). The single phase Zn1−xCoxO thin films with nominal compositions (0.00 ≤ x ≤ 0.15) were synthesized by a spray pyrolysis technique, which exhibit room temperature ferromagnetism as revealed by alternating gradient force magnetometer (AGFM) measurements. The spectroscopic measurements indicate that most of Co dopants have substituted for Zn sites in ZnO matrix and they are present in divalent Co2+ (d7) state with tetrahedral symmetry according to the atomic multiplet calculations. The O 1s NEXAFS spectra suggest strong hybridization between O 2p and Co 3d electrons within ZnO matrix. The Co 2p XMCD measurements rule out the magnetism due to the presence of Co clusters, and show that Co–O–Co bonding provides localized magnetic moments leading to ferromagnetism. 相似文献
8.
Thin films of GaAsxN1−x alloys were deposited by reactive rf magnetron sputtering of GaAs target with a mixture of argon and nitrogen as the sputtering gas. Growth rate was found to decrease from ∼ 7 μm/h to ∼ 2 μm/h as the nitrogen content increased from 0% to 40%. XRD and TEM studies of the films reveal the presence of hexagonal GaN with a significant increase of the lattice parameters in a narrow range of composition of the sputtering gas (5-10% nitrogen), which is attributed to the incorporation of arsenic. The limited availability of nitrogen in the sputtering atmosphere is found to encourage the incorporation of arsenic in the alloy films. Optical absorption coefficient spectra of the films were obtained from reflection and transmission data. The effect of arsenic incorporation is seen in the optical absorption spectra of the films, which show a continuous shift of the absorption edge to lower energies with respect to that of gallium nitride. 相似文献
9.
A series of mixed fluorides with general composition Ba1−xErxF2+x (0.00≤x≤1.00) were prepared by a vacuum heat treatment of the binary fluorides and analyzed by powder XRD, which revealed the phase equilibrium in BaF2-ErF3 system. The nominal compositions with x≤0.25 compositions exist as cubic fluorite type solid solution. A rhombohedral ordering is observed in the vicinity of 42 mol% of ErF3 in BaF2. A monoclinic phase with the composition Er2BaF8 dominates the ErF3-rich compositions. The compositions for x>0.67 exist as a mixture of Er2BaF8 and leftover ErF3, whereas the compositions for x<0.67 exist as a mixture of Er2BaF8 and rhombohedral fluorite derived phase. The evolution of the various phases will be discussed in reference to the powder XRD data. 相似文献
10.
Cd1 − xZnxO nanocrystalline thin films with rock-salt structure were obtained through thermal decomposition of Cd1 − xZnxO2 (x = 0, 0.37, 0.57, 1) thin films which were electrodeposited from aqueous solution at room temperature. X-ray diffraction results showed that the Zn ions were incorporated into rock salt-structure of CdO and the crystal lattice parameters decreased with the increase of Zn contents. The bandgaps of the Cd1 − xZnxO thin films were obtained from optical transmission and were 2.40, 2.51, 2.63 and 3.25 eV, respectively. 相似文献
11.
Crystal structures of BiMn0.97Al0.03O3 (I) at 300 and 470 K and BiMn0.9Al0.1O3 (II) at 90 and 300 K were studied with synchrotron X-ray powder diffraction. The strong Jahn-Teller distortion, observed at 300 K in I and associated with orbital order, disappeared at 470 K completely for one site and partially for the second site. The Mn/Al-O distances were very close to each other in I at 470 K and in II at 90 and 300 K indicating that orbital order did not appear in II even at 90 K. Magnetic properties of I and II were investigated with specific heat, high-temperature dc magnetic susceptibility, and ac magnetic susceptibility using different driving ac and applied dc magnetic fields and different ac magnetic field frequencies. The anomaly on the specific heat associated with a magnetic transition was strongly suppressed in II compared with that of I and BiMnO3. 相似文献
12.
A series of mixed fluorides with general composition Ba1−xNdxF2+x (0.00≤x≤1.00) was prepared by vacuum heat treatment of the mixture of starting fluorides, and analyzed by powder XRD. From the XRD analysis, the low temperature phase equilibria in BaF2-NdF3 system is elucidated. The initial compositions in this series, that is, up to the nominal composition Ba0.65Nd0.35F2.35 (x≤0.35) exist as cubic fluorite-type solid solution. Beyond the solid solution limit, that is, x>0.35, a rhombohedral fluorite related ordered phase is observed. Further, NdF3-rich compositions (x≥0.50) exist as a mixture of rhombohedral ordered phase and NdF3 (tysonite)-type phase. About 10 mol% of BaF2 could be retained in the NdF3 lattice, forming a tysonite-type solid solution, under the short annealed and slow cooled conditions. 相似文献
13.
In this work, a series of Cr1−xAlxN (0 ≤ x ≤ 0.7) coatings were deposited on high speed steel substrates by a vacuum arc reactive deposition process from two lateral rotating elemental chromium and aluminum cathodes in a flowing pure nitrogen atmosphere. The composition, structural, mechanical, and tribological properties of the as-deposited coatings were systematically characterized by energy dispersive analysis of X-rays, X-ray diffraction, nanoindentation, and ball-on-disc tribometer experiments. All of the as-deposited CrAlN coatings exhibited a higher hardness than CrN, showing a maximum hardness of about 40 GPa (at around X = 0.63) which is twice higher than that of the CrN. The wear performance under ambient conditions of the CrAlN coatings was found much better, with both lower friction coefficient and wear rate, than TiAlN coatings deposited by the same technique. The wear rate of the CrAlN coatings against alumina counterpart was about 2-3 orders in magnitude lower than that of the TiAlN coatings. Selected CrAlN coatings with the highest hardness were also deposited on some WC-based end-mills. An evident better performance of the CrAlN-coated end-mills was observed than the TiAlN-coated ones for cutting a hardened tool steel material under high speed machining conditions. 相似文献
14.
CuIn1 − xAlxSe2 (CIAS) thin films were grown by a two stage process. Cu, In and Al layers were sequentially evaporated and subsequently heated with elemental selenium in a quasi-closed graphite box. Different x values (0 ≤ x ≤ 0.6) were obtained by varying the Al and In precursor layers thicknesses. Selenization conditions such as Se amount provided during the selenization process were adjusted in order to optimize the film properties. Polycrystalline CuIn1 − xAlxSe2 thin films with chalcopyrite structure were obtained. Referred to CuInSe2 thin films the lattice parameters, the (112) orientation and the average crystallite size decreased and the band gap energy increased with increasing Al content. To optimize structural properties of the CIAS films a higher Se amount was required as the x value increased. The incorporation of Al changed the thin film morphology towards smaller grain sizes and less compact structures. 相似文献
15.
Tianjin Zhang Jinzhao Wang Baishun Zhang Juan Jiang Runkun Pan Jun Wang 《Materials Research Bulletin》2008,43(3):700-706
Compositionally graded (Ba1−xSrx)TiO3 (BST) thin films, with x decreasing from 0.3 to 0, were deposited on Pt/Ti/SiO2/Si and Ru/SiO2/Si substrates by radio frequency magnetron sputtering technology. The microstructure and dielectric properties of the graded BST thin films were investigated. It was found that the films on Ru electrode have better crystallization, and that RuO2 is present between the Ru bottom electrode and the graded BST thin films by X-ray diffraction and SEM analysis. Dielectric measurement reveals that the graded BST thin films deposited on Ru bottom electrode have higher dielectric constant and tunability. The enhanced dielectric behavior is attributed to better crystallization as well as smaller space charge capacitance width and the formation of RuO2 that is more compatible with the BST films. The graded BST films on Ru electrode show higher leakage current due to lower barrier height and rougher surface of bottom electrode. 相似文献
16.
Ming-Feng KuoChao-Ming Fu Chao-Yi HsuJung-Chuan Lee Yu-Hua LeeChia-Ou Chang Chan-Shin Chou 《Thin solid films》2011,519(23):8235-8238
The Al doping effects on high-frequency magneto-electric properties of Zn1 − x − yAlxCoyO (x = 0-10.65 at.%) thin films were systematically studied. In the current work, the Zn1 − x − yAlxCoyO thin films were deposited by magnetron co-sputtering onto quartz substrates. The magneto-impedance spectra of the thin films were measured by an impedance analyzer. Among all the doped films studied, the thin film with 6.03 at.% Al-doping showed the highest ac conductivity and relaxation frequency. To characterize the relaxation mechanism underlying the magneto-electric properties, a Cole-Cole impedance model was applied to analyze the impedance spectra. The analyzed result showed that the magneto-impedance of the Zn1 − x − yAlxCoyO is contributed by multiple processes of magnetization dynamics and dielectric relaxation. The results imply that Zn1 − x − yAlxCoyO may be applicable for high-frequency magneto-electric devices. 相似文献
17.
Series of the mixed fluorides with the general composition M1−xNdxF2+x (0.00≤x≤1.00; M=Sr2+ and Ca2+) were prepared by a vacuum heat treatment of the appropriate mixtures of MF2 (M=Ca and Sr) and NdF3. The products obtained were analyzed by powder X-ray diffraction, which revealed the phase relations in these systems. At the MF2-rich compositions a fluorite-type solid solution was observed in both systems. The typical solid solution limits of NdF3 in the SrF2 and CaF2 lattice are about 40 and 45 mol%, respectively. The incorporation of NdF3 in the fluorite lattice of CaF2 causes an expansion of the unit cell volume. The unit cell volume of the fluorite lattice in Sr1−xNdxF2+x system surprisingly remains constant throughout the solid solution range. The NdF3 (tysonite) type phase separates out beyond the solid solution limit, in both systems. Also, it was observed that about 15 and <10 mol% of CaF2 and SrF2, respectively, could be retained in the NdF3, maintaining the tysonite lattice. No fluorite or tysonite-related ordered phases were observed in these systems. 相似文献
18.
Akira Yoshiasa Daisuke SakamotoHiroki Okudera Makio OhkawaKen’ich Ota 《Materials Research Bulletin》2003,38(3):421-427
Na1−xKxMgF3 (0≤x≤1) solid-solutions were synthesized and the phase diagram of NaMgF3-KMgF3 system was determined by high temperature X-ray powder diffraction experiments and differential thermal analysis (DTA). This system is characterized by a complete series of solid solutions, with a minimum in the solidus at 30 mol% KMgF3 and 1279 K. No immiscibility gap was found. The crystal system changes from orthorhombic to cubic at x=0.22 at room temperature. The volume change of the unit cell as a function of composition shows a large deviation (excess volume) from Vegard’s law for solid solution. The transition temperatures of NaMgF3 and Na0.9K0.1MgF3 from orthorhombic to cubic are 1043 and 723 K, respectively. The transition temperature decreases rapidly by the effect of replacing Na by K. Axial ratios of b/a and c/√2a in orthorhombic NaMgF3 and Na0.9K0.1MgF3 decrease linearly with temperature toward the transition and then discontinuously changes to cubic at the transition point. 相似文献
19.
Chalcopyrite CuIn1−xAlxSe2 (CIAS) thin films with an atomic ratio of Al/(In + Al) = 0.4 were grown by a two-stage process onto soda-lime glass substrates. The selenisation was carried out at different temperatures, ranging from 400 °C to 550 °C, for metallic precursors layers evaporated with two different sequences. The first sequence, C1, was evaporated with the Al as the last layer, while in the second one, C2, the In was the last evaporated element. The optical, structural and morphological characterisations led to the conclusion that the precursors sequence determines the crystallisation pathway, resulting in C1 the best option due to the homogeneity of the depth distribution of the elements. The influence of the selenisation temperature was also studied, finding 540 °C as the optimum one, since it allows to achieve the highest band gap value for the C1 sequence and for the given composition. 相似文献
20.
Ho-Chieh YuKuan-Zong Fung 《Materials Research Bulletin》2003,38(2):231-239
La1−xSrxCuO2.5−δ (LSCu), which exhibit excellent electrical conductivity and oxygen vacancies were investigated as potential cathode materials for solid oxide fuel cell (SOFC) applications. The structure stability, electrical conductivity, cathodic overpotential, and the reactivity with yttria-stabilized zirconia (YSZ) were examined in this study. It was found that the LSCu perovskite was obtained only when the addition of strontium fell in the range between 15 and 30%. With more than 20% of strontium addition, this material showed excellent electrical property and immunity to the reaction with YSZ at 800 °C. The conductivities of LSCu were as high as 900 S/cm at 600 °C, and 800 S/cm at 800 °C. The cathodic overpotential of this material was approximately 3.8 and 10.6 mV at a current density of 100 mA/cm2 at 850 and 750 °C, respectively. These properties are superior to Sr-doped lanthanum manganite (LSM), which is the state-of-the-art cathode material of SOFCs. 相似文献