The effect of impurity atoms on the multiplication of edge dislocations

Vlasov, N. M.; Zaznoba, V. A.

doi:10.1134/1.1340885

Cited by 3 publications

(3 citation statements)

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“…7,8 However, dislocations are also known to interact with point defects. In the case of metals, it is generally assumed that impurity defects will pin dislocations, 9 leading to a reduction in the rate of dislocation multiplication and hence in creep rate for any given stress. The mechanism for this was first discussed by Cottrell and Bilby and involves the interaction of the stress field of the dislocation and point defect; a mechanism that can be understood without recourse to the atomic scale.…”

Section: Introductionmentioning

confidence: 99%

Defects and dislocations in MgO: atomic scale models of impurity segregation and fast pipe diffusion

et al. 2010

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Graphical contents entry Atomic scale simulations show the path taken by magnesium vacancies undergoing rapid pipe diffusion along the core of a edge dislocation in MgO. S ummary Dislocations are known to influence the formation and migration of point defects in crystalline materials. We use a recently developed method for the simulation of the cores of dislocations in ionic materials to study the energy associated with the formation of point defects close to the core of a edge dislocation in MgO. These are compared then with the energies for the same point defects in otherwise perfect MgO. It is find that all defect species are bound to the dislocation core, with binding energies of between 1.5 and 2.0 eV. Vacancies are found to be most stable when they remove undercoordinated ions at the tip of the extra half plane, while the impurities are most stable within the dilatational stress field below the glide plane. By mapping the distribution of energies for point defects around the dislocation line we reveal the coupling between the effective point defect size and the stress field associated with the dislocation. We also examine the energy barrier to diffusion of vacancies along the dislocation line and find that vacancy migration along the dislocation line will be substantially enhanced compared to migration through the dislocation free crystal structure. Activation energies are 0.85-0.92 of the barrier in the perfect crystal, demonstrating the importance of pipe diffusion along extended defects for low temperature mobility in ionic materials.

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Section: Introductionmentioning

confidence: 99%

Defects and dislocations in MgO: atomic scale models of impurity segregation and fast pipe diffusion

et al. 2010

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“…Dislocations can also migrate through the mineral lattice, further enhancing chemical exchange [2]. It is generally assumed that impurity defects will pin dislocations [3], leading to a reduction in the rate of dislocation multiplication and hence in creep rate for any given stress in metals. An impurity atmosphere around the edge dislocation raises the critical shear stress necessary to form a closed dislocation loop [3].…”

Section: Introductionmentioning

confidence: 99%

“…It is generally assumed that impurity defects will pin dislocations [3], leading to a reduction in the rate of dislocation multiplication and hence in creep rate for any given stress in metals. An impurity atmosphere around the edge dislocation raises the critical shear stress necessary to form a closed dislocation loop [3]. The impurity atoms will be redistributed along the bent segment by diffusion because of the chemical potential gradient.…”

Section: Introductionmentioning

confidence: 99%

Large Scale Atomistic Simulation with Electrostatics: The Case of Cation Impurity Segregation Along an Edge Dislocation Line

Zhang

Wright

Gale

et al. 2010

2010 Sixth IEEE International Conference on E-Science Workshops

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The movement of impurities and point defects in materials plays a key role in determining their rheological properties, both by permitting diffusional creep and by allowing recovery by dislocation climb. Impurity and point defect diffusion can also control the kinetics of phase transitions and grain growth, and can determine the rate of chemical equilibration between phases. Thus the study of point defects and their migration has been of considerable interest. So far, studies using computer simulation methods have concentrated on point defects moving through otherwise perfect crystals. Here, we report calculations on the behavior of the isovalent substitutional cation impurities, Ca and Sr, close to the core of an 1 2 < 110 > {110} edge dislocation in MgO. By mapping the distribution of energies for impurities and point defects around the dislocation line, we reveal that the impurities are segregated towards and trapped inside the MgO edge dislocation core. In addition, Mg vacancies will strongly partition to the impurity bearing dislocation. We also find that the presence of impurities slightly increases the Mg migration activation energy. However, impurity migration in the dislocation core is substantially enhanced compared to migration through the dislocation-free crystal structure. Activation energies are 0.76-0.86 of the barrier in the perfect crystal, demonstrating the importance of pipe diffusion along extended defects for low temperature mobility in ionic materials.

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Stresses modeling in multilayer semiconductor structures of automobile regulators and predicting the reliability of their operation

Adarchin

Kosushki

Gurin³

et al. 2020

Izv. vysš. učebn. zaved., Mater. èlektron. teh.

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The problems of increasing the reliability of microelectromechanical systems are considered on the example of an automobile voltage regulator. A model of the process is proposed and a study of the effect of temperature on the formation of stress fields in semiconductor structures of active elements of the controller is carried out. The studies assumed of a possible reason for the change in the parameters of the regulator due to the appearance of defects in the crystal structure of the semiconductor material in the structures of integrated voltage regulators. For the study, a mathematical model was proposed that describes the behavior of a semiconductor element of a real car voltage regulator. It was found that the distribution of stresses in the structures is uneven and the maximum value of stresses reaches the edges., An increase in temperature gradients in the structures of regulators leads to the formation of dislocations that change the electrical characteristics of devices. As a result of modeling, it has been established that thermoelastic stresses arising in the process of manufacturing and functioning of semiconductor structures of a regulator in regulators of this type can cause a change in the structure of a semiconductor device due to relaxation of elastic stresses at dislocations. in cars. Measures are proposed, including thermostating of the sensitive elements of microelectromechanical structures, which will increase their service life.

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The effect of impurity atoms on the multiplication of edge dislocations

Cited by 3 publications

References 0 publications

Defects and dislocations in MgO: atomic scale models of impurity segregation and fast pipe diffusion

Defects and dislocations in MgO: atomic scale models of impurity segregation and fast pipe diffusion

Large Scale Atomistic Simulation with Electrostatics: The Case of Cation Impurity Segregation Along an Edge Dislocation Line

Stresses modeling in multilayer semiconductor structures of automobile regulators and predicting the reliability of their operation

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