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Showing papers on "Transmission electron microscopy published in 1994"


Journal ArticleDOI
TL;DR: In this article, a twinned 9R structure was found in precipitates slightly larger than 4nm in diameter, following transformation from b.c.c to c.c, indicating that further twinning must occur during growth in the 9R phase.
Abstract: Transmission electron microscopy and high-resolution electron microscopy investigations of the structure of Cu precipitates in the size range 4–30 nm were carried out as part of a wider investigation into Cu precipitation from thermally aged Fe-Cu and Fe-Cu-Ni ferritic model alloys. A twinned 9R structure was found to be present in precipitates slightly larger than 4nm in diameter, following transformation from b.c.c. Two twin-related 9R variants were observed in all the smallest 9R particles studied. The 9R precipitates were observed to grow subsequently as spherical, multiply twinned particles up to approximately 17 nm, indicating that further twinning must occur during growth in the 9R phase. At sizes larger than 17 nm, a second transformation to the more stable 3R structure takes place. Observations on these 3R particles indicate that, following transformation from 9R, the precipitates are untwinned and have a distorted f.c.c. structure. The particle-matrix orientation is close to, but not ex...

366 citations


Journal ArticleDOI
TL;DR: In this paper, the overall defects in LaMnO3+δ have been studied by powder neutron diffraction, electron diffraction and high resolution transmission electron microscopy on a sample with the formal composition LaO3.

311 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the crystallographic and electronic structure of γ-alumina surfaces obtained by thermal oxidation of Al foil by combining X-ray photoelectron spectroscopy, electron energy loss spectrography, transmission electron microscopy and transmission electron diffraction investigations.

205 citations


Journal ArticleDOI
TL;DR: Ion assisted pulsed laser deposition has been used to produce films containing ≳85% sp3-bonded cubic boron nitride (c‐BN) as mentioned in this paper.
Abstract: Ion‐assisted pulsed laser deposition has been used to produce films containing ≳85% sp3‐bonded cubic boron nitride (c‐BN) By ablating from a target of hexagonal boron nitride (h‐BN), BN films have been deposited on heated (50–800 °C) Si(100) surfaces The growing films are irradiated with ions from a broad beam ion source operated with Ar and N2 source gasses Successful c‐BN synthesis has been confirmed by Fourier transform infrared (FTIR) spectroscopy, high‐resolution transmission electron microscopy (TEM), selected‐area electron diffraction, electron energy‐loss spectroscopy, and x‐ray diffraction The films are polycrystalline and show grain sizes up to 300 A In addition, Rutherford backscattering, elastic recoil detection, and Auger electron spectroscopies have been used to further characterize the samples The effects of varying ion current density, substrate growth temperature, growth time, and ion energy have been investigated It is found that stoichiometric films with a high c‐BN percentage ca

204 citations


Journal ArticleDOI
TL;DR: The microstructure of low resistivity (∼ 2 × 10−4 Ω cm) Sn-doped In2O3 (ITO) thin films prepared by multipass d.c. magnetron sputter deposition with an ITO (10 wt.% SnO2) target onto soda-lime glass substrates was investigated using plan-view and cross-sectional transmission electron microscopy (TEM) and X-ray diffraction as discussed by the authors.

196 citations


Journal ArticleDOI
TL;DR: In situ reflection high-energy electron diffraction and cross-sectional transmission electron microscope observations have revealed that the BaTiO3 films are epitaxially grown on Pt/MgO substrates from the initial stage without any other phase formation as mentioned in this paper.
Abstract: Thin films of BaTiO3 have been epitaxially grown on Pt(001)/MgO(100) substrates by reactive evaporation Structural and electrical properties were investigated as a function of film thickness In situ reflection high‐energy electron diffraction and cross‐sectional transmission electron microscope observations have revealed that the BaTiO3 films are epitaxially grown on Pt/MgO substrates from the initial stage without any other phase formation From the images of an atomic force microscope, it has been found that islands of BaTiO3 are present on the bare Pt surface at the initial stage of deposition; the island structure changes to a continuous layer above 12 nm in thickness and BaTiO3 grows in a two‐dimensional mode The lattice parameters and the dielectric properties are dependent on the film thickness Thermodynamic theory was introduced to explain the thickness dependence of the relative dielectric constant er Good agreement between the experimental results and the theoretical calculations leads to

159 citations


Journal ArticleDOI
TL;DR: Transmission electron microscopy and electron energy loss line spectra show that the fillings of partially filled graphitic fibers form as solid cores and may correspond to pure metal.
Abstract: We report the vapor phase growth of partially filled graphitic fibers, 20-30 nm in diameter and up to a micron in length, during a manganese catalyzed carbon electric arc discharge. The fiber morphology resembles that of catalytic chemical vapor deposited carbon filaments but the inside hollow contains intermittent precipitates and continuous filling of Mn that at times occupy g50% of fiber lengths. Transmission electron microscopy and electron energy loss line spectra show that the fillings form as solid cores and may correspond to pure metal.

154 citations


Journal ArticleDOI
TL;DR: The microstructure and preferred orientations of rapid thermally annealed Pb(Zr0.53, Ti0.47)O3 films, deposited on Pt/Ti/SiO2/Si electrode/substrates by solution-gel spinning, have been investigated using analytical and high-resolution electron microscopy and X-ray diffraction as mentioned in this paper.
Abstract: The microstructure and preferred orientations of rapid thermally annealed Pb(Zr0.53, Ti0.47)O3 films, deposited on Pt/Ti/SiO2/Si electrode/substrates by solution-gel spinning, have been investigated using analytical and high-resolution electron microscopy and X-ray diffraction. The temperature of pyrolysis of the PZT filMS was found to influence the preferred orientation of the film: lower temperatures (350-degrees-C) favored a (111) orientation, whereas higher temperatures (420-degrees-C) favored a (100) orientation. Excess Pb was used to control the A-site stoichiometry of the film particularly at the film surface where Pb-deficient crystals could often be observed. The absence of these crystals was shown to be correlated with an improvement in the dielectric response.

146 citations


Journal ArticleDOI
TL;DR: In this article, the newly discovered fullerene-like nested polyhedra (NP) and nanotubules of metal dichalcogenides by scanning tunneling microscopy (STM) and high-resolution transmission electron microscopy is reported.
Abstract: Extensive investigation of the newly discovered fullerene-like nested polyhedra (NP) and nanotubules of metal dichalcogenides by scanning tunneling microscopy (STM) and high-resolution transmission electron microscopy is reported. Long-term spontaneous (room temperature) and electron beam assisted crystallization of amorphous precursor into NP or MX 2 (M=W, Mo; X=S, Se) was observed. This, along with other findings, suggests that the NP constitute a new metastable phase between the starting amorphous material and the thermodynamically stable bulk 2H allotrope. Characterization of the apex angles by STM suggests that the apexes of the NP may contain geometrical elements such as triangles and rhombuses, which do not exist in nested carbon fullerenes

141 citations


Journal ArticleDOI
15 Jun 1994
TL;DR: In this article, the authors report on experiments carried out to synthesize CNx thin films, which were grown in an unbalanced magnetron-sputtering system by reactive sputtering of C in N2 discharges.
Abstract: There is currently considerable interest in producing new materials with extreme combinations of mechanical properties such as high hardnesses and moduli. One example of such a material is crystalline C3N4, which has been predicted to have a bulk modulus higher than that of diamond. In this paper we report on experiments carried out to synthesize CNx thin films. The films were grown in an unbalanced magnetron-sputtering system by reactive sputtering of C in N2 discharges. Si(001) substrates with the native oxide removed by thermal desorption and then kept at temperatures ranging from 150 to 600°C and substrate bias voltages Vs between 7.5 and -200 V were used. The films were analysed using X-ray diffraction, transmission electron microscopy (TEM). Auger electron spectroscopy, Rutherford backscattering and nano-indentation tests. Typically the films were grown at rates of 5 nm s−1 to total thicknesses of 300 nm. Owing to an extensive re-sputtering, only low negative bias voltages (−80

137 citations


Journal ArticleDOI
TL;DR: In this paper, the structure and the morphology of crystallized amorphous silicon (α•Si) films which were deposited on glass and annealed in a conventional furnace or by rapid thermal process (RTP) are studied using transmission electron microscopy (TEM).
Abstract: The structure and the morphology of crystallized amorphous silicon (α‐Si) films which were deposited on glass and annealed in a conventional furnace or by rapid thermal process (RTP) are studied using transmission electron microscopy (TEM). The ellipsoidal shape of the grains is attributed to the fast solid‐state crystallization along the two mutually perpendicular 〈112〉 and 〈110〉 crystallographic directions. The growth is solely based on the twin formation. The stability of the microtwins was studied by RTP and in situ TEM heating experiments. The effect of the film thickness on the preferred orientation of the grains is discussed. Very thin films exhibit (111) preferred orientation due to the strongly anisotropic rate of growth of the nuclei, which imposes an orientation filtering due to a growth velocity competition. The mode of growth of these films is compared with poly‐Si films grown by low‐pressure chemical‐vapor deposition.

Journal ArticleDOI
TL;DR: The postgrowth modification of diamond-like amorphous hydrogenated carbon a-C:H films by laser treatment has been studied by transmission electron microscopy and Raman spectroscopy as discussed by the authors.
Abstract: The post-growth modification of diamond-like amorphous hydrogenated carbon a-C:H films by laser treatment has been studied by transmission electron microscopy and Raman spectroscopy a-C:H films grown on Si substrates by benzene decomposition in a rf glow discharge were irradiated with 15 ns pulses of a KrF-excimer laser with fluences in the range of E=50–700 mJ/cm2 At fluences below 100 mJ/cm2 an increase in the number of graphitic clusters and in their ordering was evidenced from Raman spectra, while the film structure remained amorphous according to electron microscopy and electron diffraction observations At higher fluences the appearance of diamond particles of 2–7 nm size, embedded into the lower crystallized graphitic matrix, was observed and simultaneously a progressive growth of graphite nanocrystals with dimensions from 2 nm to 4 nm was deduced from Raman measurements The maximum thickness of the crystallized surface layer (≈400 nm) and the degree of laser annealing are limited by the film ablation which starts at E>250 mJ/cm2 The laser-treated areas lose their chemical inertness In particular, chemical etching in chromium acid becomes possible, which may be used for patterning the highly inert carbon films

Journal ArticleDOI
TL;DR: In this article, the microstructure of the sol-gel material SnO 2, prepared by the solgel method, was studied by scanning electron microscopy and x-ray diffraction.
Abstract: The microstructure of ${\mathrm{SnO}}_{2}$, prepared by the sol-gel method, was studied by scanning electron microscopy, transmission electron microscopy, high-resolution electron microscopy, and x-ray diffraction. A nanosponge structure was observed. There is much surface and interface structure. The interfaces vary in type from amorphous to crystalline. The high density of defects greatly influences the physical and chemical properties of this material.

Journal ArticleDOI
TL;DR: A new and simple in situ method to fabricate adherent and dense hydroxyapatite (HA) coatings at relatively low deposition temperatures (500-600 degrees C) and exhibit a fully crystalline single-phase structure is demonstrated.


Journal ArticleDOI
TL;DR: In this paper, the physical and chemical microstructure of spider dragline was revealed by analytical transmission electron microscopy individual crystallites were imaged within the amorphous matrix They are irregularly shaped, approximately 70-100 nm in diameter, and uniformly distributed throughout the matrix Electron diffraction determined their space group to be P21 The corresponding orthogonal cell has lattice parameters of a = 1331 A (β-sheet repeat), b = 944 A (interchain repeat within β-sheets), and c = 2088 A (repeat along polypept
Abstract: We report the first direct observations of the physical and chemical microstructure of spider dragline, revealed by analytical transmission electron microscopy Individual crystallites were imaged within the amorphous matrix They are irregularly shaped, approximately 70–100 nm in diameter, and uniformly distributed throughout the matrix Electron diffraction determined their space group to be P21 The corresponding orthogonal cell has lattice parameters of a = 1331 A (β-sheet repeat), b = 944 A (interchain repeat within β-sheets), and c = 2088 A (repeat along polypeptide chain) Electron energy loss spectroscopy indicated compositional variations within the matrix, and between the crystallites and matrix Most notably, calcium was found exclusively in the crystallites Attempts to produce synthetic analogues of dragline, which exhibits an unparalleled combination of strength, stiffness, and toughness, cannot depend solely on duplicating the constituent proteins The complex hierarchical microstructure of the natural material must be taken into account © 1994 John Wiley & Sons, Inc

Journal ArticleDOI
TL;DR: In this article, the authors have grown aluminum nitride thin films by ultrahigh vacuum reactive sputter deposition on Si(111) and Si(001) substrates, and showed results of film characterization by Raman scattering, ion beam channeling, and transmission electron microscopy.
Abstract: We have grown aluminum nitride thin films by ultrahigh vacuum reactive sputter deposition on Si(111) and Si(001) substrates. We show results of film characterization by Raman scattering, ion beam channeling, and transmission electron microscopy, which establish the occurrence of epitaxial growth of wurtzitic aluminum nitride thin films on Si(111) at temperatures above 600 °C. In contrast, microstructural characterization by transmission electron microscopy shows the formation of highly oriented polycrystalline wurtzitic aluminum nitride thin films on Si(001). Real‐time substrate curvature measurements reveal the existence of large intrinsic stresses in aluminum nitride thin films grown on both Si(111) and Si(001) substrates.

Journal ArticleDOI
TL;DR: In this paper, the microstructure and composition of macro particles (droplets) in TiN films deposited by arc evaporation on cemented-carbide substrates were investigated using a combination of scanning electron microscopy, X-ray diffraction (XRD), energy-dispersive Xray analysis and electron energy loss spectroscopy.
Abstract: The microstructure and composition of macro particles (droplets) in TiN films deposited by arc evaporation on cemented-carbide substrates were investigated using a combination of scanning electron microscopy, cross-sectional transmission electron microscopy (TEM) including lattice resolution TEM, X-ray diffraction (XRD), energy-dispersive X-ray analysis and electron energy loss spectroscopy. The apparent surface number density of droplets, with diameters of 0.1–10 μm, was found to be about 10 7 cm −2 . Droplets were incorporated in the film at various distances from the substrate surface. In between the droplets, the TiN films exhibited a dense columnar microstructure. On top of the incorporated droplets, the TiN films grew in a pronounced columnar structure with a column diameter close to the droplet diameter. The core of the droplets consisted of equiaxed grains of an α-Ti superstructure containing approximately 3–5 at.% N whereas the rim of the droplets had increasing nitrogen content up to 50 at.% XRD showed evidence for the presence of Ti 2 N possibly at the rim of the droplets. Beneath each droplet a large voided region was observed with the shape of a flattened torus as a consequence of droplets being incorporated in the solid state and subsequent shadowing of the Ti flux to the film.

Journal ArticleDOI
TL;DR: In this paper, high uniform, smooth nanocrystalline diamond films have been fabricated with a magnetoactive microwave chemical vapor deposition system, and the growth rate is 0.1 μm/h.
Abstract: Highly uniform, smooth nanocrystalline diamond films have been fabricated with a magnetoactive microwave chemical vapor deposition system. The top and bottom magnet currents were 145 and 60 A, respectively, while the microwave power and substrate temperature were controlled at 1500 W and 850 °C, respectively during deposition. The total processing pressure was regulated at 40 Pa (300 mTorr) with gas‐flow rates of 30 sccm of hydrogen, 2.4 sccm of methane, and 1 sccm of oxygen. Diamond films obtained under these conditions have grain sizes between 0.1 and 0.3 μm, and a mean roughness of 14.95 nm. The growth rate is 0.1 μm/h. Characterization techniques have involved x‐ray diffraction, Raman spectroscopy, scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. Both x‐ray and electron diffraction patterns show no evidence of graphitic phase. Although a high density of twins and stacking faults was revealed by high‐resolution electron microscopy, compact diamond grains, and...

Journal ArticleDOI
TL;DR: In this article, high-resolution transmission electron microscopy of MCM-41 showed the hexagonal shape of the pores and allowed direct observation of the transition from a lamellar to hexagonal phase.
Abstract: High-resolution transmission electron microscopy of MCM-41 shows for the first time clearly the hexagonal shape of the pores, and allows direct observation of the transition from a lamellar to the hexagonal phase.

Journal ArticleDOI
TL;DR: In this article, the formation of porous p-type 6H-SiC was confirmed by transmission electron microscopy, with interpore spacings in the range of 1-10 nm.
Abstract: We report the formation of porous p-type 6H-SiC. The existence of uniformly dispersed pores was confirmed by transmission electron microscopy, with interpore spacings in the range of 1-10 nm. The porous film as a whole is a single crystal. Luminescence peaks above the normal band gap of 6H-SiC have been observed in the porous layer, but were not distinguished in the bulk SiC substrate. Quantum confinement is discussed as a possible mechanism for the luminescence effects.

Journal ArticleDOI
TL;DR: In this paper, thin films of AIN were grown by plasma source molecular beam epitaxy system on Si(111, Si(100), Al2O3(0001), Al 2O3 (1102), and Al 2 O3(1102) substrates, and thermal conductivity of these thin films was investigated by the thermal wave-mirage technique.

Journal ArticleDOI
TL;DR: In this paper, the atomistic structure of a near Σ11 (N211) grain boundary in ultrapure α-AI2O3 bicrystals was determined by quantitative high-resolution transmission electron microscopy (HRTEM).
Abstract: The atomistic structure of a near Σ11 (N211) grain boundary in ultrapure α-AI2O3 bicrystals was determined by quantitative high-resolution transmission electron microscopy (HRTEM). High-resolution imaging revealed an atomically sharp interface with a characteristic periodic pattern at (0111) ‖ (0111) facets. The pattern was analyzed by comparing the HRTEM micrographs with simulated images of different structures that had been relaxed by static-lattice calculations. The best agreement with experiment was reached for the grain boundary structure with the lowest energy (1.7 J·m−2). Although this structure reproduces the relative translation state of the adjacent crystals to within 0.02 nm, the calculated structure was not in complete agreement with the periodic pattern at the grain boundary. The origin of this difference is probably due to a slight misalignment of the two crystals adjacent to the boundary.

Journal ArticleDOI
Hanyi Lou1, Fuhui Wang1, Shenlong Zhu1, Bangjie Xia1, Lixin Zhang1 
TL;DR: The oxide scales formed on the cast Ni-based alloy K38G and its sputtered, micrograined coating at 1000°C in air have been investigated by optical, electron probe microanalysis, scanning and transmission electron microscopy, and X-ray diffraction measurements as mentioned in this paper.
Abstract: The oxide scales formed on the cast Ni-based alloy K38G and its sputtered, micrograined coating at 1000°C in air have been investigated by optical, electron probe microanalysis, scanning and transmission electron microscopy, and X-ray diffraction measurements. Complex oxide scales formed on the cast alloy composed of the outer layer of Cr 2 O 3 , TiO 2 and NiCr 2 O 4 and the inner layer of Al 2 O 3 are prone to spallation. On the contrary, only a thin oxide layer of Al 2 O 3 can be observed on the sputtered alloy, and it was very adherent. The formation of the Al 2 O 3 layer and its excellent adhesion may be attributed to the microcrystalline grains of the sputtered material.

Journal ArticleDOI
TL;DR: In this paper, an ion-assisted pulsed laser deposition method was used to produce CNx thin films with x = 0.70 by using a graphite target to be ablated while simultaneously bombarding the substrate with nitrogen ions.
Abstract: We have produced CNx thin films with x = 0–0.70 by using an ion-assisted pulsed laser deposition method. In this method a graphite target was ablated while simultaneously bombarding the substrate with nitrogen ions. The deposition rate, ion current, substrate temperature and substrate bias were varied to enhance nitrogen incorporation and to optimize the properties of the thin films. The films were characterized using Rutherford backscattering-channelling. Auger electron spectroscopy, electron energy loss spectroscopy, transmission and scanning electron microscopy, Raman spectroscopy and nano-indentation hardness measurements. The average nitrogen concentration was found to vary (N/C atomic ratio) in the range 0–0.70. The transmission electron microscopy studies showed that these films were polycrystalline with a fine-grain equiaxed structure (average size 10 nm) above a substrate temperature of 200°C. The sp3/sp2 ratio was determined to be 25%–30% using electron energy loss spectroscopy. The Raman studies showed two peaks at 1285 and 1575 cm−1 corresponding to sp3 and sp2 bonding respectively. The films exhibited qualitatively very high hardness and thermal annealing resistance.

Journal ArticleDOI
TL;DR: In this paper, highly oriented pyrolytic graphite was irradiated with 300 keV electrons at temperatures between 25 and 657 °C in a transmission electron microscope (TEM).
Abstract: One of the main problems found in the nuclear applications of graphite is its dimensional instability under irradiation, involving both swelling and shape changes. In order to understand better the mechanisms that give rise to these changes, highly oriented pyrolytic graphite was irradiated with 300 keV electrons at temperatures between 25 and 657 °C in a transmission electron microscope (TEM). Microscopic dimensional changes and structural disordering were studied in directions parallel and perpendicular to the graphite basal plane. Changes in the specimen length were investigated by measuring the distance between two markers on the specimen surface in TEM images. Changes in the lattice parameter and the crystalline structure were studied by a TEM diffraction technique. In agreement with reported results, large increases in the specimen length and the lattice parameter were observed along the c-axis direction, whereas a relatively small decrease was observed along the a-axis. In irradiation studies conducted at room temperature, it was found that the dimensional change saturates at high dose, at an elongation along the c-axis direction of about 300%. High resolution microscopy revealed that the microstructure had become nanocrystalline. Electron energy loss spectroscopy results showed that the volume change was recovered at this stage. These observations are discussed in terms of point defect evolution and its effects on the microstructure of irradiated graphite.

Journal ArticleDOI
TL;DR: In this article, the formation of conducting composite membranes of polypyrrole with in-house prepared and commercial (Biotran) microporous polyamides was described.

Journal ArticleDOI
TL;DR: In this article, the authors used an analytical transmission electron microscope with a field emission gun to investigate the nucleation behavior of the Al-Cu-Mg-Ag alloy and found that Ag and Mg segregate to the habit plane interface and that some Mg may also be present within the precipitates.
Abstract: The composition of {111} θ precipitate plates one and two unit cells thick in an Al-Cu-Mg-Ag alloy was investigated using an analytical transmission electron microscope with a field emission gun. These studies revealed that Ag and Mg segregate to the {111} habit plane interface and that some Mg may also be present within the precipitates. The effect of Ag and Mg on the nucleation behaviour of {111} θ precipitate plates is discussed.

Journal ArticleDOI
TL;DR: In this article, the ordered vacancy compound CuIn3Se5 (100) was obtained by molecular beam epitaxy from Cu2Se and In2Se3 sources, and electron probe microanalysis and x-ray diffraction have confirmed the composition for the 1•3•5 phase.
Abstract: Epitaxial growth of the ordered vacancy compound CuIn3Se5 has been achieved on GaAs (100) by molecular beam epitaxy from Cu2Se and In2Se3 sources. Electron probe microanalysis and x‐ray diffraction have confirmed the composition for the 1‐3‐5 phase and that the films are single‐crystal CuIn3Se5 (100). Transmission electron microscopy characterization of the material also showed it to be single crystalline. Structural defects in the layer consisted mainly of stacking faults. Photoluminescence measurements performed at 7.5 K indicate that the band gap is 1.28 eV. Raman spectra reveal a strong polarized peak at 152 cm−1, which is believed to arise from the totally symmetric vibration of the Se atoms in the lattice.

Journal ArticleDOI
01 Jan 1994-Carbon
TL;DR: The phase and stoichiometry of α-GdC2 have been determined using a combination of techniques, such as X-ray diffraction and high-resolution electron microscopy.