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1.
A relation between a metallic film covering on diamond formed during growth and nanosized inclusions in HPHT as-grown diamond single crystals 总被引:3,自引:0,他引:3
L.-W. Yin M.-S. Li Z.-G. Gong Y.-J. Bai F.-Z. Li Z.-Y. Hao 《Applied Physics A: Materials Science & Processing》2003,76(7):1061-1065
One of the most important characteristics and basic phenomena during diamond growth from liquid metal catalyst solutions saturated
with carbon at high temperature–high pressure (HPHT) is that there exists a thin metallic film covering on the growing diamond,
through which carbon-atom clusters are delivered to the surface of the growing diamond by diffusion. A study of microstructures
of such a metallic film and a relation between the thin metallic film and the inclusions trapped in HPHT as-grown diamond
single crystals may be helpful to obtain high-purity diamond single crystals. It was found that both the metallic film and
the HPHT as-grown diamond single crystals contain some nanostructured regions. Examination by transmission electron microscopy
suggests that the microstructure of the thin metallic film is in accordance with nanosized particles contained in HPHT as-grown
diamond single crystals. The nanosized particles with several to several tens of nanometers in dimension distribute homogeneously
in the metallic film and in the diamond matrix. Generally, the size of the particles in the thin metallic film is relatively
larger than that within the diamond matrix. Selected area electron diffraction patterns suggest that the nanosized particles
in the metallic film and nanometer inclusions within the diamond are mainly composed of f.c.c. (FeNi)23C6, hexagonal graphite and cubic γ-(FeNi). The formation of the nanosized inclusions within the diamond single crystals is thought
not only to relate to the growth process and rapid quenching from high temperature after diamond synthesis, but also to be
associated with large amounts of defects in the diamond, because the free energy in these defect areas is very high. The critical
size of carbide, γ-(FeNi)and graphite particles within the diamond matrix should decrease and not increase according to thermodynamic
theory during quenching from HPHT to room temperature and ambient pressure.
Received: 13 September 2001 / Accepted: 12 June 2002 / Published online: 17 December 2002
RID="*"
ID="*"Corresponding author. Fax: +86-0531/295-5081; E-mail: yinlw@sdu.edu.cn 相似文献
2.
L.W. Yin M.S. Li Z.D. Zou D.S. Sun Z.Y. Hao Z.G. Gong Z.Y. Yao 《Applied Physics A: Materials Science & Processing》2001,72(3):373-375
The growth-front interface of a diamond single crystal, which was grown from the Fe-Ni-C system under high pressure and high
temperature (HPHT), has been directly observed by transmission electron microscopy (TEM) for the first time. The presence
of a cellular interface suggests that the diamond is grown from solution and there exists a narrow supercooling zone in front
of the solid–liquid interface. Diamond-growth parallel layers were also found, which indicates that the diamond grows from
solution layer by layer. It provides direct evidence that the diamond is synthesized through graphite dissolution and transformation
to subcritical diamond particles in a molten catalyst, diamond subcritical particle connection to form diamond clusters, diffusion
of the diamond clusters to the growing diamond, and unification of the diamond clusters on the growing diamond crystal.
Received: 17 July 2000 / Accepted: 27 October 2000 / Published online: 10 January 2001 相似文献
3.
L.-W. Yin M.-S. Li J.-J. Cui Y.-J. Song F.-Z. Li Z.-Y. Hao 《Applied Physics A: Materials Science & Processing》2001,73(5):653-657
For understanding the mechanism of diamond growth at high temperature–high pressure (HTHP) from a metallic catalyst–graphite
system, it is of great interest to perform atomic force microscopy (AFM) experiments, which provide a unique technique different
from that of normal optical and electronic microscopy studies, to study the topography of HTHP as-grown diamond single crystals.
In the present paper, we report first AFM results on diamond single crystals grown from a Fe-Ni-C system at HTHP to reveal
the growth mechanism of diamond single crystals at HTHP. AFM images for as-grown diamond samples show dark etch pits on the
(111) surface, indicating dislocations. Some fine particles about 100–300 nm in dimension were directly observed on the (100)
diamond surface. These particles are believed to have been formed through transition of graphite to diamond under the effect
of the catalyst and to have been transported to the growing diamond surface through a metallic thin film by diffusion. The
roughness of the (100) diamond surface is found to be about several tens of nanometers through profile analysis. The diamond
growth at HTHP, in a sense, could be considered as a process of unification of these fine diamond particles or of carbon-atom-cluster
recombination on the growing diamond crystal surface. Successive growth interlayer steps on the (111) diamond surface were
systemically examined. The heights of the growth interlayer steps were measured by sectional analysis. It was shown that the
heights of the growth interlayer steps are quite different and range from about 10 to 25 nm. The source of the interlayer
steps might be dislocations. The diamond-growth mechanism at HTHP could be indicated by the AFM topography of the fine diamond
particles and the train-growth interlayer steps on the as-grown diamond surfaces.
Received: 29 March 2001 / Accepted: 20 August 2001 / Published online: 2 October 2001 相似文献
4.
H.Y. Wang Z.W. Ma E.Y. Jiang Y.J. He H.S. Huang 《Applied Physics A: Materials Science & Processing》1999,68(5):559-562
The structure and magnetic properties of Fe-N and Fe-Ti-N films have been studied as a function of annealing temperature Ta with a transmission electron microscope and a vibrating sample magnetometer. The as-prepared Fe-N films consist of the γ′-Fe4N and α′′-Fe16N2 phases, and the Fe-Ti-N films are composed of the γ′-Fe4N, α′′-Fe16N2, and TiN phases. The structural changes with annealing temperature in the Fe-N films are distinct. The α′′-Fe16N2 decomposes into α+γ′ phases in the Fe-N film annealed at about 300 °C, and it disappears in the film annealed at 350 °C. Annealing of the Fe-Ti-N
films shows no structural changes between room temperature (RT) and 500 °C. The saturation magnetization 4πMS and coercivity Hc of the Fe-N films change drastically with the annealing temperature Ta, whereas those of the Fe-Ti-N films do not change with Ta up to 500 °C. These results indicate that the additon of Ti may improve the thermal stability of Fe-N films.
Recieved: 6 Juli 1998 / Accepted: 19 Oktober 1998 / Published online: 10 March 1999 相似文献
5.
T. Füller M. Konuma J. Zipprich F. Banhart 《Applied Physics A: Materials Science & Processing》1999,69(6):597-603
Silicon-germanium layers are grown from metallic solution on (100) and (111) silicon substrates. On (111) Si, coherently strained
dislocation-free SiGe layers are obtained with thicknesses larger than predicted by the current models of misfit-induced strain
relaxation. A comprehensive characterisation by imaging, diffraction, and analytical electron microscopy techniques is carried
out to determine the critical thickness, study the onset of plastic relaxation, and explain the particular growth mechanisms
leading to an unexpectedly high thickness of elastically strained SiGe layers. A vertical Ge concentration gradient and the
formation of step edges on the layers, where lateral strain relaxes locally, explain the high critical thickness. The model
of Matthews and Blakeslee is modified in order to match the experimental observations for solution-grown SiGe layers.
Received: 29 July 1999 / Accepted: 29 July 1999 / Published online: 27 October 1999 相似文献
6.
G. Kuri 《Applied Physics A: Materials Science & Processing》1999,68(6):699-703
Analytical electron microscopy, high-resolution X-ray diffraction and combined Rutherford backscattering spectrometry and
channeling experiments have been used to investigate the radiation damage and the effect of post-implantation annealing on
the microstructure of GaAs(100) single crystals implanted with 1.00 MeV Cu+ ions to a dose of ≈ 3×1016 cm-2 at room temperature. The experiments reveal the formation of a thick and continuous amorphous layer in the as-implanted state.
Annealing up to 600 °C for 60 min does not result in the complete recovery of the lattice order. The residual disorder in
GaAs has been found to be mostly microtwins and stacking fault bundles. The redistribution of implanted atoms during annealing
results in the formation of nano-sized Cu particles in the GaAs matrix. The X-ray diffraction result shows a cube-on-cube
orientation of the Cu particles with the GaAs lattice. The depth distribution and size of the Cu particles have been determined
from the experimental data. A tentative explanation for these results is presented.
Received: 15 February 1999 / Accepted: 18 February 1999 / Published online: 28 April 1999 相似文献
7.
The formation of correlations due to collisions in an interacting nucleonic system is investigated. Results from one-time
kinetic equations are compared with the Kadanoff and Baym two-time equation with collisions included in Born approximation.
A reasonable agreement is found for a proposed approximation of the memory effects by a finite duration of collisions. This
form of collision integral is in agreement with intuitive estimates from Fermi's golden rule. The formation of correlations
and the build up time is calculated analytically for the high temperature and the low temperature limit. Different approximate
expressions are compared with the numerical results. We present analytically the time dependent interaction energy and the
formation time for Gau?- and Yukawa type of potentials.
Received: 25 November 1998 / Revised version: 11 January 1999 相似文献
8.
Flat layered structure and improved photoluminescence emission from porous silicon microcavities formed by pulsed anodic etching 总被引:2,自引:0,他引:2
Z.H. Xiong L.S. Liao X.M. Ding S.H. Xu Y. Liu L.L. Gu F.G. Tao S.T. Lee X.Y. Hou 《Applied Physics A: Materials Science & Processing》2002,74(6):807-811
Single-mode, highly directional and stable photoluminescence (PL) emission has been achieved from porous silicon microcavities
(PSMs) fabricated by pulsed electrochemical etching. The full width at half maximum (FWHM) of the narrow PL peak available
from a freshly etched PSM is about 9 nm. The emission concentrates in a cone of 10° around the normal of the sample, with
a further reduced FWHM of ∼5.6 nm under angle-resolved measurements. Only the resonant peak is present in such angle-resolved
PL spectra. No peak broadening is found upon exposure of the freshly prepared PSM to a He-Cd laser beam, and the peak becomes
somewhat narrower (∼5.4 nm) after the PSM has been stored in an ambient environment for two weeks. At optimized etching parameters,
even a 4-nm FWHM is achievable for the freshly etched PSM. In addition, scanning electron microscopy (SEM) plane-view images
reveal that the single layer porous Si formed by pulsed current etching is more uniform and flatter than that formed by direct
current (dc) etching, demonstrated by the well-distributed circular pores with small size in the former in comparison with
the irregular interlinking pores in the latter. The SEM cross-section images show the existence of oriented Si columns of
10 nm diameter along the etching direction within the active layer, good reproducibility and flat interfaces. It is thus concluded
that pulsed current etching is superior to dc etching in obtaining flat interfaces within the distributed Bragg reflectors
because of its minor lateral etching.
Received: 7 March 2001 / Accepted: 23 July 2001 / Published online: 30 October 2001 相似文献
9.
J. Gebauer F. Rudolf A. Polity R. Krause-Rehberg J. Martin P. Becker 《Applied Physics A: Materials Science & Processing》1999,68(4):411-416
14 cm-3 in FZ-Si was obtained.
Received: 2 June 1998 / Accepted: 20 November 1998 / Published online: 24 February 1999 相似文献
10.
The effect of oxidation on the structure of nickel nanoparticles 总被引:1,自引:0,他引:1
B. Rellinghaus S. Stappert E.F. Wassermann H. Sauer B. Spliethoff 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):249-252
The structural properties of nickel nanoparticles which are prepared by means of DC sputtering in argon and subsequently oxidized
in ambient air are reported. Ex situ structural and chemical investigations utilizing (high resolution) transmission electron microscopy and electron energy loss
spectroscopy reveal that the particles consist of a metallic core surrounded by an oxide shell. The lattice constant of the
nickel core is found to increase significantly with decreasing particle size. This widening of the nickel lattice is attributed
to an interfacial stress that originates from the lattice mismatch between nickel and nickel oxide.
Received 21 December 2000 相似文献
11.
Honeycomb-like alignments of carbon nanotubes were prepared by pyrolysis of a metal phthalocyanine at 950 °C in an Ar/H2 flow. A simple synthetic method has been developed for a large-scale synthesis of aligned carbon nanotubes normal to a substrate
surface.
Received: 15 June 2000 / Accepted: 21 June 2000 / Published online: 2 August 2000 相似文献
12.
L. Thomé G. Rizza F. Garrido M. Gusso L. Tapfer A. Quaranta 《Applied Physics A: Materials Science & Processing》1998,67(2):241-247
2 matrix by ion-beam mixing of SiO2/Ag multilayers is studied via Rutherford backscattering spectrometry, optical absorption, and transmission electron microscopy
experiments. In a first step, irradiation with MeV heavy ions transforms the continuous Ag layers into a string of micrometer-sized
Ag inclusions. This mechanism can be attributed to lateral segregation of metallic atoms induced by irradiation. In a second
step, the Ag inclusions are broken up by incoming ions and Ag nanoclusters are formed by agglomeration of mobile Ag atoms.
The latter mechanism is likely due to a combination of ballistic mixing and radiation-induced segregation or radiation-enhanced
diffusion processes. The size of the metallic nanoclusters formed depends also on the irradiation temperature.
Received: 27 October 1997/Accepted: 3 February 1998 相似文献
13.
M. Klimenkov J. von Borany W. Matz D. Eckert M. Wolf K.-H. Müller 《Applied Physics A: Materials Science & Processing》2002,74(4):571-575
Co nanoparticles fabricated by ion beam synthesis in SiO2 films were investigated with transmission electron microscopy and superconducting quantum interference device technique.
Variation of the thermal treatment enables the formation of Co nanoclusters of different sizes ranging from 2 to 40 nm. Small
nanoclusters of about 2–3 nm are amorphous, whereas clusters above 7 nm show the configuration of cubic Co nanocrystals. Measurements
of magnetisation at temperatures between 2 K and 360 K reveal superparamagnetic behaviour for the small nanoclusters up to
3 nm and ferromagnetism for clusters above 7 nm.
Received: 12 February 2001 / Accepted: 3 May 2001 / Published online: 27 June 2001 相似文献
14.
Yu.A. Nastishin M. Kléman J. Malthête H.T. Nguyen 《The European physical journal. E, Soft matter》2001,5(3):353-357
We have shown that cholesteryl nonanoate, a thermotropic compound which is well known to exhibit pretransitional effects at
the smectic A (SmA) cholesteric (N*) transition (W.L. McMillan, Phys. Rev. A 4, 1238 (1971); 6, 936 (1972)), has in fact a TGBA phase in between. Our arguments rely on the observation of new TGBA defects, either in Robinson
spherulites cooled from the N* phase or in free-standing films. The same new defects can be obtained in a well-documented
TGBA phase of a tolane compound. We analyze qualitatively the TGBA defects in both geometries, in particular their relation
to the disclination radius of the N* Robinson spherulites.
Received 12 February 2001 相似文献
15.
Focal Conic Domains (FCDs) in smectic phases often assemble according to a particular rule, experimentally discovered by G.
Friedel, the law of corresponding cones (l.c.c.). This paper reports various results relating to this type of association. First we show that a l.c.c. contact between
2 focal conic domains has a vanishing energy, yielding metastable local equilibrium. Then we use some projective properties of conic sections to extend the celebrated Apollonian tiling, which describes a tilt grain boundary (TiGB) of vanishing disorientation
made of toric focal conic domains, to any TiGB. Finally we present a realistic model of the energy of the TiGB, which we compare to the energy of a TiGB split into dislocations, and to the energy of a curvature wall. This model
explains why FCD tilings show macroscopic zones not filled with FCDs.
Received 21 June 1999 and Received in final form 10 September 1999 相似文献
16.
Yusuf Atici 《Applied Physics A: Materials Science & Processing》1997,64(3):307-314
+ Si(100) and bare Si(100) wafers by low pressure chemical vapour deposition (LPCVD) at 230–280 °C. The films were investigated
by transmission electron microscopy (TEM). The cross-sectional TEM samples of W/Si(100) exhibited a fine scale interface roughness,
which was attributed to the surface preparation. Irregular W plug structures were observed depending on the predeposition
procedures. It was observed that an insufficient deposition of W films on the contact surface leads to the presence of aluminium
around and underneath the plugs. This was observed by energy dispersive X-ray spectrometry (EDX). A study, using conventional
electron diffraction, confirmed that no silicides formed at the interfaces of W-bare Si(l00) wafers.
Received: 16 December 1996/Accepted: 6 May 1997 相似文献
17.
This paper deals with the implantation of high-energy (1.0–3.0 MeV) atomic and molecular Al+ ions in Si(100) to a fluence of 5×1014 Al atoms/cm2 at room temperature. The molecular effect, i.e. the increase of the displacement yield compared with the sum of the atomic
yields, and the damage formation as well as defect behaviour after annealing have been investigated. A detailed experimental
study has been made of the evolution of extended secondary defects which form during thermal anneals of Al+ or Al2
+ irradiated silicon. The samples have been examined using combined Rutherford backscattering and channeling experiments together
with transmission electron microscopy observations. The surface structure of the implanted wafers has been measured by atomic
force microscopy. The results for the implantation-induced roughness at the Si surface, resulting from Al+ or Al2
+ irradiation at the same energy/atom, total atomic fluence, flux rate, and irradiation temperature, are presented and discussed.
Received: 19 August 1999 / Accepted: 20 October 1999 / Published online: 23 February 2000 相似文献
18.
R. Turan B. Aslan O. Nur M.Y.A. Yousif M. Willander 《Applied Physics A: Materials Science & Processing》2001,72(5):587-593
We have studied the effect of the strain relaxation on the band-edge alignments in a Pt/p-Si1-xGex Schottky junction with x=0.14 by internal photoemission spectroscopy and current–voltage measurements. We have shown that
the variations in the band-edge alignments can be observed directly by measuring the optical and electrical properties of
a simple Schottky junction. The strain in the Si1-xGex layer has been partially relaxed by thermal treatments at two different temperatures. The degree of relaxation and other
structural changes have been determined by a high-resolution X-ray diffractometer. Both optical and electrical techniques
have shown that the barrier height of the Pt/Si0.86Ge0.14 junction increases with the amount of relaxation in the Si1-xGex layer. This shows that the valence-band edge of the Si1-xGex layer moves away from the Fermi level of the Pt/Si1-xGex junction. The band-edge movement results from the increase in the band gap of the Si1-xGex layer after the strain relaxation. This result agrees with the theoretical predictions for the strain-induced effects on
the Si1-xGex band structure.
Received: 18 October 2000 / Accepted: 19 December 2000 / Published online: 23 March 2001 相似文献
19.
D. Reinelt P. Boltenhagen N. Rivier 《The European physical journal. E, Soft matter》2001,4(3):299-304
The “staircase” (2,1,1) foam structure in an ordered foam under expansion in a cylindrical tube and the structural transition
to the “bamboo” (1,1,0) structure are studied experimentally, analytically, and numerically using the Surface Evolver minimization
program. An analytical expression of the oblique interface in the (2,1,1) structure, a minimal surface, but curved by stretching
of the foam, is given as a classic example of singular perturbation (boundary layer) theory. The structural transition from
staircase structure to bamboo structure takes place at a considerable dilation. The transition is not due to an edge length
tending to zero continuously with dilation, but results from the equilibrium (2,1,1) solution losing its stability due to
a saddle node bifurcation.
Received 3 August 2000 相似文献
20.
J. Boneberg H.-J. Münzer M. Tresp M. Ochmann P. Leiderer 《Applied Physics A: Materials Science & Processing》1998,67(4):381-384
Received: 20 April 1998/Accepted: 2 June 1998 相似文献