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1.
We study the technique of nanoindentation hardness measurement applied to extremely hard and elastic thin films. We do the
study with the aid of Hertz’s solutions for elastic contacts. The effect of different apical angles in ideally sharp conical
diamond indenters is analyzed. In addition, the blunt tip shape of practical diamond indenters is discussed. The area function
of the tip of real indenters is deduced from experimental nanoindentation measurements performed with these indenters on fused
quartz. Triangular-base pyramidal indenters with Berkovich and cube corner geometries are considered. Theoretical hardness
values applying Hertz’s and Oliver and Pharr’s methods of analysis are obtained and compared with the experimental data deduced
from nanoindentation measurements performed on very hard and elastic ta-C films. The theoretical analysis shows a necessary
dependence of the calculated hardness values with the apical angle of the indenter in totally elastic materials and to some
extent in elastoplastic materials. Moreover, when the indenter tip is blunt or when there are inaccuracies in the measured
area function of the indenter tip, hardness values decrease for very small penetration depths. Besides, in these films, because
of their very small thickness, measured hardness values also decrease for measurements with penetration depths larger than
a fraction of film thickness, due to the effects of the softer substrate.
Received: 13 June 2000 / Accepted: 21 June 2000 / Published online: 5 October 2000 相似文献
2.
M.F. Fyhn J. Lundsgaard Hansen J. Chevallier A. Nylandsted Larsen 《Applied Physics A: Materials Science & Processing》1999,68(2):259-262
1-x Snx (0.01≤x≤0.04) layers on Si(001) and relaxed Si-Ge substrates. The Si1-xSnx layers were investigated using Rutherford backscattering spectrometry, atomic force microscopy, transmission electron microscopy
and preferential-etching experiments. The investigation of surfactant-mediated growth of epitaxial Si1-xSnx was motivated by a possible use of relatively higher growth temperatures without relaxation by surface precipitation. It
is demonstrated that higher growth temperatures are attainable when Bi is used as surfactant if the surface-segregated Sn
layer is relatively small, equivalent to Si1-xSnx layers of low strain. The increase in growth temperature leads to a significant improvement in the crystalline quality of
these Si1-xSnx layers.
Received: 4 December 1998/Accepted: 9 December 1998 相似文献
3.
F. Lelarge O. Dehaese E. Kapon C. Priester 《Applied Physics A: Materials Science & Processing》1999,69(3):347-351
Atomic force microscopy (AFM) in air is used to study the (110) cleaved surface of strained (100) InxGa1-xAs/ InP heterostructures for different compositions and thicknesses of the ternary compound layers. We find that the elastic
strain relaxation induces a surface undulation of a few ? amplitude, even for very small misfits, provided the layers are
thick enough. Using finite-element calculations of the strain relaxation near the cleaved edge, we reproduce quantitatively
the AFM observations for compressive- as well as for tensile-strained layers with an accuracy better than 0.1 nm. This demonstrates
the ability of AFM to quantify strain distributions by making use of surface profile measurements.
Received: 9 November 1998 / Accepted: 11 March 1999 / Published online: 7 July 1999 相似文献
4.
A method for the experimental determination of the net charge distribution over the atoms in a large class of compounds is
described. The method is based on X-ray photoemission spectroscopy and requires the determination of two core-level energies
per constituting atomic species. Two special cases of large conceptual and practical interest are discussed: the silicon charge
in CoSi2, Si1-xGex (0≤x≤0.3), SiC, Si3N4 and SiO2, and the aluminum charge in aluminum-doped zeolites.
Received: 20 March 2000 / Accepted: 28 March 2000 / Published online: 21 March 2001 相似文献
5.
I. Ardelean M. Peteanu V. Simon F. Ciorcas V. Ioncu 《Applied Physics A: Materials Science & Processing》2001,73(4):481-484
The xCuO(100-x)[70TeO2·25B2O3·5SrF2] vitreous system was studied in the 0.3≤x≤20 mol %CuO concentration range, by means of electron paramagnetic resonance (EPR)
and magnetic susceptibility measurements. At low concentrations the Cu2+ ions are in axially distorted octahedral symmetry units giving resonance absorptions at g≈4.3. For x≥3 mol %CuO the copper
ions are mostly involved in clusters yielding resonance absorptions at g≈2.05 in the EPR spectrum. Non-magnetic Cu+ ions are present in samples with x>5 mol %CuO. Only dipole–dipole interactions involving the copper ions were evidenced in
this glass system. Ligand field fluctuations were revealed in all investigated samples.
Received: 24 August 2000 / Accepted: 17 November 2000 / Published online: 21 March 2001 相似文献
6.
W. Shuicai H. Junfang X. Dong Z. Changjun H. Xun 《Applied physics. B, Lasers and optics》2001,72(7):819-821
We have constructed a three-wavelength Ti:sapphire femtosecond laser with an independent tunable wavelength (λ1) and two variable central wavelengths (λ2 and λ3) for use with the multi-excited photosystem II. Stable sub-40-fs pulses are generated. The λ1-wavelength pulses can be tuned independently from 750 nm to 850 nm. The center wavelengths λ2 and λ3 can be varied from 760 nm to 840 nm.
Received: 14 April 2000 / Revised version: 5 September 2000 / Published online: 27 April 2001 相似文献
7.
D. Music U. Kreissig Zs. Czigány U. Helmersson J.M. Schneider 《Applied Physics A: Materials Science & Processing》2003,76(2):269-271
Boron suboxide thin films have been deposited on Si(100) substrates by reactive RF magnetron sputtering of a sintered B target
in an Ar/O2 atmosphere. Elastic recoil detection analysis was applied to determine the film composition and density. Film structure was
studied by X-ray diffraction and transmission electron microscopy. The elastic modulus, measured by nanoindentation, was found
to decrease as the film density decreased. The relationship was affected by tuning the negative substrate bias potential and
the substrate temperature during film growth. A decrease in film density, by a factor of 1.55, caused an elastic modulus reduction
by a factor of 4.5, most likely due to formation of nano-pores containing Ar. It appears evident that the large scattering
in the published data on elastic properties of films with identical chemical composition can readily be understood by density
variations. These results are important for understanding the elastic properties of boron suboxide, but may also be qualitatively
relevant for other B-based material systems.
Received: 22 February 2002 / Accepted: 11 April 2002 / Published online: 10 September 2002
RID="*"
ID="*"Corresponding author. Fax: +46-13/288-918, E-mail: denmu@ifm.liu.se 相似文献
8.
In2(Se1-xTex)3 polycrystalline films were prepared by a dual-source thermal evaporation technique. The depositions onto glass and SnO2-coated glass substrates were carried out in a vacuum chamber and followed by an annealing in neutral ambient (Ar or N2). The structural, morphological and compositional studies of the films were made by X-ray diffraction, energy-dispersive
X-ray analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, Raman scattering and optical transmission.
Optimum conditions are investigated for the formation of the ternary compound In2(Se1-xTex)3 in order to tune the band gap by changing the Te concentration. The film properties as a function of Te amount are discussed.
It is shown that single-phase, textured and homogeneous layers of In2(Se1-xTex)3 can be grown with x≤0.2 at optimal deposition and heat treatment conditions. For x≅0.17 these films showed an energy band
gap of about 1.45 eV and an electrical conductivity at room temperature six orders of magnitude higher than that of the binary
γ-In2Se3 thin films.
Received: 9 July 1999 / Accepted: 25 November 1999 / Published online: 13 July 2000 相似文献
9.
I. Vrejoiu J.D. Pedarnig M. Dinescu S. Bauer-Gogonea D. Bäuerle 《Applied Physics A: Materials Science & Processing》2002,74(3):407-409
BaTiO3–polymer composite layers have been produced by the spin-on technique (thickness 3–10 μm). The dielectric permittivity of
the layers at room temperature can be tuned from 2.8 to approximately 33 by varying the ceramic filling from 0 to 60% by volume.
The dielectric properties of the films are almost insensitive to temperature variations in the range 20–180 °C. Free-standing
composite layers with ceramic content ≤50% are flexible without noticeable change of permittivity after repeated mechanical
bending.
Received: 22 November 2001 / Accepted: 24 November 2001 / Published online: 23 January 2002 相似文献
10.
Single crystal platelets of FeBO3 are used as magnetoelastically excited shear wave transducers in the 10–100MHz region. Due to a strong dependence of the
elastic stiffness on an applied magnetic dc field the resonance frequency is magnetically tunable in a region of about 25
percent around the centre frequency. A pulse-echo experiment was used to compare the conversion efficiencies of the FeBO3 transducer and a conventional quartz transducer. The insertion losses were found to be approximately equal for both transducers
and in accordance with the calculated values. 相似文献
11.
I.P. Johnstone L.D. Skouras 《The European Physical Journal A - Hadrons and Nuclei》2001,11(2):125-136
The matrix elements of the effective Hamiltonian in the 0g
9/2-1p
1/2 space are determined by a least-square fit to the energies of 477 levels of nuclei with 38≤Z≤50 and 47≤N≤50. The results of the calculation are found to be in better agreement with experiment than those obtained with previously
determined interactions.
Received: 31 May 2001 / Accepted: 14 June 2001 相似文献
12.
We have performed theoretical studies on the elastic and thermodynamic properties of the solid solution: Ti2AlC0.5N0.5. The lattice parameters, elastic constants, bulk, shear, Young's moduli, Poisson's ratio and Debye temperature were calculated and compared with those of the end members, Ti2AlC and Ti2AlN. The temperature dependence of the bulk moduli, thermal expansion coefficient and specific heats of Ti2AlC0.5N0.5 were obtained from the quasi-harmonic Debye model. The calculated elastic and thermodynamic properties were compared with experimental data. 相似文献
13.
The elastic constants and thermodynamic properties of Li2O for high temperatures and pressures are calculated by the ab initio unrestricted Hartree-Fock (HF) linear combination of atomic orbital (LCAO) periodic approach. The lattice constant, elastic constants, Debye temperature, and thermal expansion coefficient obtained are in good agreement with the available experimental data and other theoretical results. It is found that at zero pressure the elastic constants C11, C12 and C44, bulk modulus B and Debye temperature ΘD decrease monotonically over the wide range of temperatures from 0 to 1100 K. When the temperature , C12 approaches zero, consistently with the transition temperature 1200 K. However, with increasing pressure, they all increase monotonically and the anisotropy will weaken. 相似文献
14.
J. K. Baria 《Czechoslovak Journal of Physics》2004,54(4):469-485
A model pseudopotential depending on an effective core radius but otherwise parameter free is used to study the interatomic
interactions, phonon dispersion curves (inq and r-space analysis), phonon density of states, mode Grüneisen parameters, dynamical elastic constants (C
11,C
12 andC
44), bulk modulus (B), shear modulus (C′), deviation from Cauchy relation (C
12–C
44), Poisson’s ratio (σ), Young’s modulus (Y), behavior of phonon frequencies in the elastic limit independent of the direction (Y
1), limiting value in the [110] direction (Y
2), degree of elastic anisotropy (A), maximum frequencyω
max, mean frequency 〈ω〉, 〈ω
2〉1/2=(〈ω〉/〈ω
−1〉)1/2, fundamental frequency 〈ω
2〉, and propagation velocities of the elastic constants in Cu, Ag, Au, Ni, Pd, and Pt. The contribution of s-like electrons
is calculated in the second-order perturbation theory for the model potential while that of d-like electrons is taken into
account by introducing repulsive short-range Born-Mayer like term. Very recently proposed screening function due to Sarkar
et al. has been used to obtain the screened form factor. The theoretical results are compared with experimental findings wherever
possible. A good agreement between theoretical investigations and experimental findings has proved the ability of our model
potential for predicting a large number of physical properties of transition metals. 相似文献
15.
We have studied structural, thermodynamic, elastic, and electronic
properties of cubic IrO2 polymorph via ab initio calculations within the
LDA and GGA approximations. Basic physical properties, such as lattice
constant, bulk modulus, second-order elastic constants (Cij), and the
electronic band structures are calculated, and compared with available
experimental values. We have, also, predicted the Young's modulus, Poison's
ratio (ν), Anisotropy factor (A), sound velocities, and Debye
temperature. 相似文献
16.
Y.J. Chen J. Ding L. Si W.Y. Cheung S.P. Wong I.H. Wilson T. Suzuki 《Applied Physics A: Materials Science & Processing》2001,73(1):103-106
The magnetic microstructures and magnetotransport properties in granular CoxAg1-x films with 17%≤x≤62% were studied. Magnetic force microscopy (MFM) observations showed the presence of magnetic stripe domains
in as-deposited samples with x≥45% and the evolution of the magnetic domain patterns to in-plane domains with annealing. A
perpendicular magnetic anisotropy as high as about 8×105 ergs/cc for as-deposited Co62Ag38 and about 6×105 ergs/cc for as-deposited Co45Ag55 was observed by magnetization and torque measurements. With increasing annealing temperature, the perpendicular magnetic
anisotropy became negative. The origin of the perpendicular magnetic anisotropy may be attributed to a rhombohedral distortion
of the cubic cell due to residual substrate-film stresses. The magnetic stripe domains are the consequence of the interplay
of the indirect or direct exchange, perpendicular magnetic anisotropy and dipolar interactions. Finally, magnetoresistance
(MR) curves displayed training behaviours and different shapes when measured with different configurations (parallel, transverse
and perpendicular). It is proposed that the existence and the evolution of the magnetic domain structures strongly affect
the magnetotransport properties due to the extra contribution of the electron scattering at the domain walls. Furthermore,
an anisotropic MR also contributes to the overall MR curves.
Received: 2 March 2000 / Accepted: 28 March 2000 / Published online: 23 May 2001 相似文献
17.
The unimolecular decay of the hydrogen-bonded phenol(H2O)4
+ cluster ion was studied both experimentally and theoretically. The ion is formed by resonant two-color two-photon ionization
of the neutral cluster. If the second color exceeds the dissociation threshold of the ion, fragmentation occurs on a microsecond
time scale. By analyzing the time-of-flight (TOF) signal of the metastable ions at different excess energies the dependence
of the fragmentation rate on the excess energy can be deduced. These experimental rates are compared to microcanonical decay
constants k(E) calculated from Rice–Ramsperger–Kassel–Marcus (RRKM) theory based on ab initio data solely.
Received: 8 March 2000 / Revised version: 28 April 2000 / Published online: 5 October 2000 相似文献
18.
Microscopic calculations of weak interaction rates of nuclei in stellar environment for A = 18 to 100 总被引:2,自引:0,他引:2
J.-U. Nabi H.V. Klapdor-Kleingrothaus 《The European Physical Journal A - Hadrons and Nuclei》1999,5(3):337-339
We report here the microscopic calculation of weak interaction rates in stellar matter for 709 nuclei with A = 18 to 100
using a generalized form of proton-neutron quasiparticle RPA model with separable Gamow-Teller forces. This is the first ever
extensive microscopic calculation of weak rates calculated over a wide temperature-density grid which includes 107≤ T(K) ≤ 30 × 109 and 10 ≤ρ Ye (gcm−3) ≤ 1011, and over a larger mass range. Particle emission processes from excited states, previously ignored, are taken into account,
and are found to significantly affect some β decay rates. The calculated capture and decay rates take into consideration the
latest experimental energy levels and ft value compilations. Our calculation of electron capture and β-decay rates, in the
fp-shell, show considerable differences with a recently reported shell model diagonalization approach calculation.
Received: 16 April 1999 相似文献
19.
T.H. Cho K. Nahm S.K. You C.K. Kim J. Pelzl 《Applied Physics A: Materials Science & Processing》2000,70(5):595-597
The elastic constant, C’, of Ce3S4 has been measured as a function of temperature. It is shown that the curve is markedly different from that of La3S4. Since the only basic difference between the two compounds is the existence of a f-electron in Ce, we propose a theoretical
scheme in which the f-electron plays a crucial role. It is shown that the existence of the f-electron in Ce3S4 prevents the band Jahn–Teller type structural transition when the temperature is lowered. The theory is consistent with the
experiment and also with the theoretically predicted instability of cubic f-electronelements at zero temperature.
Received: 5 October 1999 / Accepted: 11 October 1999 / Published online: 24 March 2000 相似文献
20.
M2AlC phases, where M is a transition metal, are layered ternary compounds that possess unusual properties. In this paper, we have calculated the elastic properties of M2AlC, with M=Ti, V, Cr, Nb and Ta, by means of ab initio total energy calculations using the projector augmented-wave method. We have derived the bulk and shear moduli, Young's moduli and Poisson's ratio for ideal polycrystalline M2AlC aggregates. We have estimated the elastic modulus of Cr2AlC with 357.7 GPa while the values of all other phases are in the range 309±10 GPa. We suggest that this can be understood based on the calculated bond energies for the M-C bonds. Furthermore, our results indicate a profound elastic anisotropy of M2AlC even compared to materials with a well-established anisotropic character such as α-alumina. Finally, we have estimated the Debye temperatures of M2AlC from the average sound velocity. 相似文献