Barriers to Strain Relaxation in Epitaxial Fluorides on Si(111)

1993 ◽  
Vol 308 ◽  
Author(s):  
Weidan Li ◽  
Steve Hymes ◽  
Shyam P. Murarka ◽  
Leo J. Schowalter
Keyword(s):  
Plastic Deformation ◽  
Temperature Dependence ◽  
Mechanical Stress ◽  
Temperature Change ◽  
Energy Barrier ◽  
Strain Energy ◽  
Strain Relaxation ◽  
Dislocation Motion ◽  
Unusual Behavior ◽  
Increasing Temperature

ABSTRACTThe mechanical stress of epitaxial SrF2 and CaF2 films on Si(111) substrates has been measured as a function of temperature by the substrate curvature technique. The temperature dependence of the stress in the SrF2 film is interpreted in terms of an energy barrier to dislocation motion. When the strain energy is smaller than the value needed to overcome the barrier, the change in stress is due mainly to elastic deformation. As the temperature change increases, the strain energy becomes large enough to overcome the barrier, at which point plastic deformation initiates. Unlike SrF2, the stress behavior of the CaF2 film for increasing temperature is quite different from its behavior for decreasing temperature. This unusual behavior is not understood at this time.

scholarly journals Critical assessment of hydrogen effects on the slip transmission across grain boundaries in α -Fe

2016 ◽  
Vol 472 (2185) ◽  
pp. 20150617 ◽  
Author(s):  
I. Adlakha ◽  
K. N. Solanki
Keyword(s):  
Grain Boundaries ◽  
Intergranular Fracture ◽  
Energy Barrier ◽  
Strain Energy ◽  
Strengthening Mechanism ◽  
Dislocation Motion ◽  
Dislocation Network ◽  
Mode Transition ◽  
Slip Transmission

Grain boundaries (GBs) play a fundamental role in the strengthening mechanism of crystalline structures by acting as an impediment to dislocation motion. However, the presence of an aggressive environment such as hydrogen increases the susceptibility to intergranular fracture. Further, there is a lack of systematic investigations exploring the role of hydrogen on the dislocation–grain-boundary (DGB) interactions. Thus, in this work, the effect of hydrogen on the interactions between a screw dislocation and 〈111〉 tilt GBs in α -Fe were examined. Our simulations reveal that the outcome of the DGB interaction strongly depends on the underlying GB dislocation network. Further, there exists a strong correlation between the GB energy and the energy barrier for slip transmission. In other words, GBs with lower interfacial energy demonstrate a higher barrier for slip transmission. The introduction of hydrogen along the GB causes the energy barrier for slip transmission to increase consistently for all of the GBs examined. The energy balance for a crack initiation in the presence of hydrogen was examined with the help of our observations and previous findings. It was found that the presence of hydrogen increases the strain energy stored within the GB which could lead to a transgranular-to-intergranular fracture mode transition.

Energy Storage And Recovery In Thin Metal Films On Substrates

1997 ◽  
Vol 505 ◽  
Author(s):  
Shefford P Baker ◽  
Rose-Marie Keller ◽  
Eduard Arzt
Keyword(s):  
Plastic Deformation ◽  
Strain Energy ◽  
Dislocation Line ◽  
Line Length ◽  
Metal Films ◽  
Silicon Substrates ◽  
Cu Films ◽  
Compressive Flow ◽  
Film Substrate ◽  
Increasing Temperature

ABSTRACTDislocation segments which extend through the thickness of a film can move through the film only if dislocation line length is deposited or removed at the film/substrate and film/passivation (if any) interfaces. The dislocation density and, therefore, the energy stored in the film increase during plastic deformation. The reverse process, that is, the reduction of strain energy in the film by the reduction of dislocation line length, is here suggested to be the origin of a number of unexplained features of experimentally obtained stress-temperature curves, including very low (or even “negative”) yield stresses in compression, tensile-compressive flow stress asymmetries, increasing strength with increasing temperature upon heating, and a very strong Bauschinger-like effect which has been seen in thin Cu films. The results of stress-temperature measurements of passivated Cu thin films on silicon substrates are presented.

TEMPERATURE DEPENDENCE OF THE RAMAN FREQUENCIES IN THE γ AND β PHASES OF SOLID NITROGEN

2010 ◽  
Vol 24 (31) ◽  
pp. 6069-6078 ◽  
Author(s):  
H. YURTSEVEN ◽  
T. TUNAY
Keyword(s):  
Experimental Data ◽  
Frequency Shift ◽  
Temperature Dependence ◽  
Interaction Mechanism ◽  
Internal Mode ◽  
Unusual Behavior ◽  
Self Energy ◽  
Solid Nitrogen ◽  
Increasing Temperature ◽  
Lattice Modes

We study here the Raman frequencies of the lattice modes (γ and β phases) and of an internal mode (γ phase) as a function of temperature in solid nitrogen. The frequency shift derived from the anharmonic self energy, is fitted to the experimental data for the Raman frequencies of the modes considered here in the γ and β phases of solid nitrogen. From our fittings, we find that the Raman frequencies of the lattice modes decrease, whereas those of the internal mode increase with increasing temperature in solid nitrogen. The unusual behavior of the internal mode indicates that the interaction mechanism should be different in relation to the anharmonicity in the γ phase of solid nitrogen.

Temperature dependence of the energy barrier in X/1X nm shape-anisotropy magnetic tunnel junctions

2021 ◽  
Vol 118 (1) ◽  
pp. 012409
Author(s):  
Junta Igarashi ◽  
Butsurin Jinnai ◽  
Valentin Desbuis ◽  
Stéphane Mangin ◽  
Shunsuke Fukami ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Energy Barrier ◽  
Tunnel Junctions ◽  
Magnetic Tunnel Junctions ◽  
Shape Anisotropy

Article

1998 ◽  
Vol 76 (4) ◽  
pp. 411-413
Author(s):  
Yixing Zhao ◽  
Gordon R Freeman
Keyword(s):  
Absorption Spectrum ◽  
Optical Absorption ◽  
Temperature Dependence ◽  
Optical Absorption Spectrum ◽  
Infrared Light ◽  
Solvated Electron ◽  
Solvated Electrons ◽  
Tert Butanol ◽  
Solvent Dependence ◽  
Increasing Temperature

The energy and asymmetry of the optical absorption spectrum of solvated electrons, es- , change in a nonlinear fashion on changing the solvent through the series HOH, CH3OH, CH3CH3OH, (CH3)2CHOH, (CH3)3COH. The ultimate, quantum-statistical mechanical, interpretation of solvated electron spectra is needed to describe the solvent dependence. The previously reported optical spectrum of es- in tert-butanol was somewhat inaccurate, due to a small amount of water in the alcohol and to limitations of the infrared light detector. The present note records the remeasured spectrum and its temperature dependence. The value of the energy at the absorption maximum (EAmax) is 155 zJ (0.97 eV) at 299 K and 112 zJ (0.70 eV) at 338 K; the corresponding values of G epsilon max (10-22 m2 aJ-1) are 1.06 and 0.74. These unusually large changes are attributed to the abnormally rapid decrease of dielectric permittivity of tert-butanol with increasing temperature. The band asymmetry at 299 K is Wb/Wr = 1.8.Key words: optical absorption spectrum, solvated electron, solvent effects, tert-butanol, temperature dependence.

Effect of Plastic Deformation on the Strain Energy Release Rate in a Centrally Notched Plate Subjected to Uniaxial Tension

1966 ◽  
Vol 88 (1) ◽  
pp. 82-86 ◽  
Author(s):  
R. G. Forman
Keyword(s):  
Plastic Deformation ◽  
Energy Release Rate ◽  
Energy Release ◽  
Uniaxial Tension ◽  
Correction Factor ◽  
Release Rate ◽  
Strain Energy ◽  
Strain Energy Release Rate ◽  
Strain Energy Release ◽  
Linear Elastic

This paper presents theoretical studies on the effect of plastic deformation on the strain energy release rate, G, of a plate under uniaxial tension with a central propagating crack. The linear elastic fracture mechanics solution for G is improved by using the Dugdale model for the crack and yielded region to obtain the axial rigidity of the plate. The axial rigidity is then used to obtain the solution for the strain energy release rate as the crack propagates. It is found that plastic deformation has a pronounced effect on G. A correction factor is presented for correcting the linear elastic solution for the strain energy release rate. The correction factor is found to depend upon the nominal (gross) stress to material yield stress ratio and the crack length to plate width ratio.

Temperature Dependence of the Diffusivity–Mobility Ratio in Degenerate Semiconductors in the Presence of a Large Magnetic Field

1973 ◽  
Vol 51 (4) ◽  
pp. 491-492 ◽  
Author(s):  
A. N. Chakravarti ◽  
D. P. Parui
Keyword(s):  
Magnetic Field ◽  
Temperature Dependence ◽  
Low Temperatures ◽  
Mobility Ratio ◽  
Degenerate Semiconductors ◽  
Large Magnetic Field ◽  
Increasing Temperature

The diffusivity–mobility ratio in degenerate semiconductors in the presence of a large magnetic field is found to increase with increasing temperature at a rate which is dependent on temperature at relatively low temperatures. It is also found that, at any given temperature, the ratio is increased by the application of the field.

scholarly journals Temperature dependence of the specific heat and thermodynamic functions AК1М2 alloy, doped strontium

2019 ◽  
Vol 21 (1) ◽  
pp. 35-42 ◽  
Author(s):  
I. N. Ganiev ◽  
S. E. Otajonov ◽  
N. F. Ibrohimov ◽  
M. Mahmudov
Keyword(s):  
Heat Capacity ◽  
Gibbs Energy ◽  
Specific Heat ◽  
Temperature Dependence ◽  
Specific Heat Capacity ◽  
Thermodynamic Functions ◽  
Inverse Relationship ◽  
Alloying Element ◽  
Enthalpy And Entropy ◽  
Increasing Temperature

In the heat «cooling» investigated the temperature dependence of the specific heat capacity and thermodynamic functions doped strontium alloy AK1М2 in the range 298,15—900 K. Mathematical models are obtained that describe the change in these properties of alloys in the temperature range 298.15—900 K, as well as on the concentration of the doping component. It was found that with increasing temperature, specific heat capacity, enthalpy and entropy alloys increase, and the concentration up to 0.5 wt.% of the alloying element decreases. Gibbs energy values have an inverse relationship, i.e., temperature — decreases the content of alloying component — is up to 0.5 wt.% growing.

NANOSCOPIC PHASE SEPARATION AND THE UNIVERSAL TRANSPORT AND MAGNETIC PROPERTIES OF HIGH Tc SUPERCONDUCTORS

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3528-3531
Author(s):  
J. JUNG ◽  
H. YAN ◽  
H. DARHMAOUI ◽  
M. ABDELHADI
Keyword(s):  
Magnetic Properties ◽  
Phase Separation ◽  
Temperature Dependence ◽  
Current Density ◽  
Low Temperatures ◽  
Energy Barrier ◽  
Vortex Motion ◽  
Superfluid Density ◽  
High Tc Superconductors ◽  
High Tc

We have found the correlation between nanoscopic phase separation in the copper-oxygen planes of YBCO and TlBCCO and the transport and magnetic properties of these materials in the a-b planes such as: the temperature dependence of the critical current density Jc( T ), the temperature dependence of the superfluid density ns( T )∝1/λ2( T ) at low temperatures, the temperature dependence of the normalized logarithmic relaxation rate S(T), and the dependence of the effective energy barrier against vortex motion on the current density Ueff( J ). These properties are controlled by the ratio of the amount of an underdoped filamentary phase to that of an optimally doped one.

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