Fcc Crystallites Research Articles

Nucleation and growth of Fe on Cu(111) in the monolayer range

We have studied the condensation of Fe on Cu(111) at room temperature, 420 and 570 K in the coverage range 0.03–4 monolayers and using an Fe flux between 0.005 and 0.1 monolayer/s. The Fe deposit grows in form of flat three-dimensional islands, whose height increases with increasing substrate temperature. In contrast to the existing literature, layer-by-layer growth was never observed. The shapes of the islands and step heights strongly support the growth of fcc crystallites, which are in registry with the Cu(111) substrate.

Crystal structure of evaporated yttrium thin films

The crystal structure of evaporated yttrium thin films has been studied using X-ray diffractometry. The structure of the films is strongly dependent on substrate temperature and thickness. Films are in most cases polymorphic, and other structures different from the yttrium bulk hcp have been observed. fcc crystallites appear only at high growth temperatures. A crystallographic ordering different from the simple fcc and hcp structures is dominant at low growth temperatures and even for very thin films grown at high temperatures.

Microstructural Study of Electroless-Plated CoNiReP/NiMoP Double-Layered Media for Perpendicular Magnetic Recording

The microstructure of the electroless CoNiReP/NiMoP double-layered media was examined with various methods, focusing upon that of the in-plane anisotropy initial regions of the CoNiReP recording layers, and the origin of the initial region was discussed. It was confirmed that the initial region consists of randomly oriented fcc crystallites with Nirich composition, showing the granular condition, while the upper region with the perpendicular anisotropy consists of <002> perpendicularly oriented hcp crystallites, forming the columnar structure with 20- to 30-nm diameter. It is considered that the formation of the initial region is due to a preferential deposition of Ni onto the NiMoP underlayers, and that the thickness of the initial region changes due to a change in the condition of the NiMoP underlayers, especially that of surface activity and/or morphology at their surfaces.

Growth and structure of titanium evaporated films

The growth and structure of titanium evaporated films formed on NaCl substrates held at various temperatures have been studied by electron microscopy. Fcc and hcp crystallites with the (001), (110), (10.1), (2 1 .0) and (00.1) planes parallel to the substrate surface have been observed. Fcc and hcp crystallites with the (001) and (10.1) orientations have been found to be more stable than those with (110) and (2 1 .0) orientations. The formation energy of the hcp crystallites with (00.1) orientation was higher than that of the other fcc and hcp crystallites. Fcc crystallites with the (001) orientation grew mainly at an early growth stage but subsequently hcp crystallites also grew. The dominant growth of the fcc crystallites in the film containing both fcc and hcp crystallites caused wrinkles in the film. The close connection between the fcc crystallites and the fcc γ-phase crystal has been pointed out.

Soft magnetic properties of microcrystalline Co-Fe-Si-B alloys prepared by sputtering

The magnetic and structural properties of microcrystalline Co-Fe-Si-B films prepared by sputtering were studied. This soft-magnetic material exhibits a high rotational permeability of 1200 and a high saturation magnetization of 1.6 T. The soft-magnetic properties of this material can be explained by the fact that the thin film consists of FCC crystallites with a perfect

The tungsten/platinum interface: Strained Pt overlayers, microcrystallites and surface alloys on W(100): II. Structural aspects

A combination of LEED and polar angle resolved X-ray photoelectron diffraction (XPD) has been used to investigate the structure of strained Pt overlayers, crystallites and W/Pt surface alloys on W(100) at Pt precoverages up to 5 monolayers. Pt is found to grow pseudomorphically up to 1.5 ML at 300 K, beyond which coverage distorted hexagonal structures begin to form. XPD analysis appears to indicate that these layers have ABA type periodicity with Pt atoms located on the distorted four-fold sites in the layer below. Annealing the layers to 600 K, or depositing Pt at 600 K appears to cause relaxation of the overlayer into fcc crystallites with orientation (111)fcc‖(100)bcc, [110]fcc‖[110]bcc At higher temperatures, alloying takes place, XPD results suggesting that substitution of Pt into the W host lattice occurs. The results are discussed in relation to the electronic behaviour of the system as determined by AES and XPS (preceding paper, part I).

Microstructural analysis of crystallization processes in a Ni-based amorphous alloy

The crystallization process of an amorphous, Ni-based alloy has been investigated by X-ray diffraction and electron microscopy diffraction, imaging and chemical analysis techniques. The crystallization sequence consists of 1. (1) nucleation and growth of < 100 Å diameter fcc crystallites in an amorphous matrix, 2. (2) transformation to a fully microcrystalline, singlephase fcc microstructure, and 3. (3) precipitation of Mo 2FeB 2-type precipitates in the fcc matrix.

X-ray structure and optical properties of silver films prepared by condensation of pre-formed Ag-clusters

Polycrystalline silver films of 400 Å thickness were prepared by condensation of silver clusters preformed in the gas phase with diameters of 20, 50 and 100 Å. Using X-ray line broadening an effective diameter of = 100 Å was determined for all three samples, thus indicating that recrystallisation of the primary clusters becomes important, if their diameter is reduced below 100 Å. This behaviour is in agreement with a reduction in the internal stress, which can reach a value as high as 0.4 × 10 ??? dyne cm −2. Additionally the fcc crystallites are distorted by (111)-stacking faults in a concentration of 2???. The optical spectra of the silver also reflect the recrystallisation behaviour of the primary crystallites.

The effect of orientation, grain size and polymorphism on magnetic properties of sputtered Co-Re thin film media

The correlation between the microstructure and the magnetic hysteretic properties was investigated. The analysis of the microstructure was made using a conventional and a 2½-D TEM analysis method. The results of the investigation show that the polymorphic transformation of HCP to FCC causes the decrease in grain size of the sputtered film. The effect of the grain size, preferred orientation and polymorphism on the value of H c was investigated from a series of equiaxial-shaped particle films. The results show that the dominant factor which influences the coercivity of the film is the grain size rather than the preferred orientation or the existence of isolated FCC crystallites in the film as the result of polymorphism. The squareness ratio, M r /M ts , of the series of film was also investigated. The results show that the preferred orientation of the crystallites in the film affect the squareness of the loop.

Epitaxy of titanium oxide evaporated films

Various ways of epitaxial growth of films formed by evaporating TiO x ( x = 1.25, 1.0, 0.6) onto NaCl substrate have been studied by electron microscopy. In the films made from TiO 1.25, fcc epitaxial crystallites with (100) and (110) orientation have grown. While the former crystallites have grown preferentially along surface steps of the substrate, the latter crystallites with a rectangular shape have grown at flat regions of the substrate at relatively higher substrate temperatures. In the films made from TiO 0.6 and TiO 1.0, hcp crystallites have grown as a result of a changed stacking sequence on the {111} planes of the fcc crystallites with (100) orientation which have grown in the early growth stage of the films.

Growth and Structure of Titanium Oxide Thin Films. II.

Films formed by evaporating TiO1.0 and TiO1.25 onto NaCl cleavage surfaces held at about 470°C in a vacuum of about 10-8 Torr have been studied by electron microscopy. The compositions of the films measured by Auger electron spectroscopy were TiO0.5 and TiO0.74 when TiO1.0 and TiO1.25 were evaporated.The film made from TiO1.25 consists mainly of fcc epitaxial crystallites of (001)- and (110)-orientation having square and rectangular shapes respectively. In the film made from TiO1.0, fcc epitaxial crystallites of the same orientations as above appear in the early growth stage and then fcc crystallites which have Ti2O structure begin to grow on the {111}planes of the fcc crystallites, with the increase of the film thickness. In both films made from TiO1.0 and TiO1.25, however, little evidence for the presence of twinned fcc crystallites grown on the {111} planes of the crystallites of (001)-orientation has been found.

Growth and Structure of Titanium Oxide Thin Films. I.

Films formed by evaporating TiO onto NaCl cleavage surfaces (room temperature ∼400°C) in a vacuum of about 10-8 Torr were studied by electron microscopy. The composition measured by an X-ray micro-analyser and an Auger electron spectrometer ranged from TiO0.8 to TiO0.9 for films formed at room temperature and the oxygen in the films decreased as the substrate temperature increased. The diffraction patterns of the films changed from halo-like rings to hcp rings passing through a stage of broad fcc rings with the increase of the substrate temperature. They also verified that the film had many stacking faults. Epitaxial fcc crystallites which were found to grow preferentially along steps of the substrate surface were also formed at above 150°C. The origin of the stacking fault was discussed on the basis of Paterson's theory and the phase diagram of titanium oxide.

On the validity of the capillarity approximation in the rate theory of homogeneous nucleation

An Einstein model is used to calculate the internal vibrational free energy of approximately spherical fcc crystallites as a function of crystallite size at T/θ = 1. It is found that the free energy per surface atom does not become convergent until a size of about 3 × 10 7 atoms is reached. The excess free energy at convergence is used to define the macroscopic surface tension for use in the capillarity approximation. The internal free energy of microcrystallites containing of the order of 100 atoms is fortuitously well described by the capillarity approximation. A good estimate of the total free energy of the microcrystallite (nucleus) is obtained from the capillarity approximation only by adding the contributions from free translation and rotation and the replacement partition function.