Thermal Memories Research Articles

Propagation of plane waves in nonlocal semiconductor nanostructure thermoelastic solid with fractional derivative due to ramp-type heat source

In this paper, propagation of thermoelastic waves in semi-conducting nanostructure medium is studied. First, the governing equations are formulated with the help of coupled nonlocal elasticity theory, thermoelastic three-phase-lag model, and equation of motion. Heat equation with fractional order is incorporated to study thermal effects on the propagation of wave. The problem is solved using Fourier series and Laplace transform to obtain the exact expressions of physical fields. The distributions of the nondimensional carrier density and stresses are obtained and illustrated graphically. The effects of nonlocal parameter, fractional order parameter, and time parameter on these wave characteristics are concerned and discussed in detail. Some semiconductor materials as Silicon (Si) and Germanium (Ge) are used to make the numerical simulation and some comparisons in different thermal memories are made.

Optical Properties of Electrochemically Gated La1−xSrxCoO3−δ as a Topotactic Phase‐Change Material

AbstractMaterials with tunable infrared refractive index changes have enabled active metasurfaces for novel control of optical circuits, thermal radiation, and more. Ion‐gel‐gated epitaxial films of the perovskite cobaltite La1−xSrxCoO3−δ (LSCO) with 0.00 ≤ x ≤ 0.70 offer a new route to significant, voltage‐tuned, nonvolatile refractive index modulation for infrared active metasurfaces, shown here through Kramers–Kronig‐consistent dispersion models, structural and electronic transport characterization, and electromagnetic simulations before and after electrochemical reduction. As‐grown perovskite films are high‐index insulators for x < 0.18 but lossy metals for x > 0.18, due to a percolation insulator‐metal transition. Positive‐voltage gating of LSCO transistors with x > 0.18 reveals a metal‐insulator transition from the metallic perovskite phase to a high‐index (n > 2.5), low‐loss insulating phase, accompanied by a perovskite to oxygen‐vacancy‐ordered brownmillerite transformation at high x. At x < 0.18, despite nominally insulating character, the LSCO films undergo remarkable refractive index changes to another lower‐index, lower‐loss insulating perovskite state with Δn > 0.6. In simulations of plasmonic metasurfaces, these metal‐insulator and insulator‐insulator transitions support significant, varied mid‐infrared reflectance modulation, thus framing electrochemically gated LSCO as a diverse library of room‐temperature phase‐change materials for applications including dynamic thermal imaging, camouflage, and optical memories.

Thermo-Elastodifusive Waves in Semiconductor Excitation Medium with Laser Pulses under Two Temperature Photo-Thermoelasticity Theory

The current work aims to investigate elasto-thermodiffusive wave propagation in a homogeneous, isotropic, and thermally conducting excited semiconductor medium. The two-temperature theory is utilized in the context of the linear photo-thermoelasticity (PTE) theory of semiconductors. Thermal and elastic memories found in the equations for heat, motion, and charge carrier field are taken into account. The governing equations are applied according to the mass-diffusion transport processes in one dimension (1D), under the influence of optoelectronics with a non-Gaussian laser pulse. Laplace transforms for dimensionless quantities are utilized to obtain the analytical linear solutions for the main quantities during thermoelastic (TD) and electronic (ED) deformation. The numerical approximations solutions of the primary relevant relations are done in the Laplace inverse time domain to observe the exact expressions of the main physical quantities according to some boundary surface conditions. The physical parameters of silicon (Si) semiconductor material are used to obtain the numerical computational results. According to the difference of the thermal memories and two-temperature parameters, the wave propagation of the physical fields is obtained graphically and the results are discussed and analyzed theoretically.

Moore–Gibson–Thompson Stability Model in a Two-Temperature Photonic Semiconductor Excited Medium Affected by Rotation and Initial Stress

In this paper, the two-temperature theory is used to examine a novel model that generalizes the Moore–Gibson–Thompson (MGT) effect according to two-dimensional electronic/thermoelastic deformation. The main equations for a semiconductor medium in the context of the impact of rotation are explained in terms of the impact of the initial hydrostatic stress at the free surface. The normal-mode approach is used to derive the precise formulae for the fundamental physical quantities (i.e., normal displacement, normal load stress, electronic diffusion (carrier density), dynamic and conductive temperature distribution) under the influence of the two-temperature coefficient. The comparison with the base state is performed using linear stability analysis. To make some comparisons based on the various values of thermal memories, the influence of a number of novel parameters is applied to each of our primary physical quantities, such as the rotation parameter and the initial stress. An example of the main fields’ perturbation is also obtained and graphically described.

A Novel Model of Semiconductor Porosity Medium According to Photo-Thermoelasticity Excitation with Initial Stress

Investigated is a novel model in the photo-thermoelasticity theory that takes into account the impact of porosity and initial stress. A generalized photo-thermoelastic that is initially stressed and has voids is taken into consideration for the general plane strain problem. The solutions for the fundamental variables in two dimensions are obtained using the Laplace–Fourier transforms method in two dimensions (2D). Physical fields such as temperature, carrier concentration, normal displacement, and change in volume fraction field can all be solved analytically. The plasma of electrons, thermal load, and mechanical boundary conditions at the porosity medium’s free surface are used to show certain illustrations. The context of the Laplace–Fourier transformation inversion operations yields complete solutions. To complete the numerical simulation and compare several thermal memories under the influence of the porosity parameters, silicon (Si), a semiconductor porosity material, is used. The main physical variables are described and graphically displayed with the new parameters.

Response of two-temperature semiconductor model photomechanical and thermal waves during electrons-holes interaction processes

A novel mathematical-physical model is introduced in the context of the two-temperature thermoelasticity theory which describes the interaction between electrons and holes in semiconductors material. The response of the elasto-thermo- mechanical continuous waves is investigated during thermo-mass-diffusion transport processes. The photothermal (PT) technique is applied for the exciting medium. The one-dimensional (1D) Cartesian coordinate is used to describe the governing equations. Dimensionless quantity is used in the Laplace transform domain. To obtain the unknown variables, some conditions are applied at the free surface of the medium to get the main quantities analytically. The conversion of the Laplace transform technique has been employed with some numerical approximations to obtain the exact expressions of the main physical fields. The computational results have been introduced of silicon material to illustrate the impacts of the two temperature parameter and thermal memories on the wave propagation of the physical fields according to photo-thermoelasticity theory.

Laser Short-Pulse Effect on Thermodiffusion Waves of Fractional Heat Order for Excited Nonlocal Semiconductor

In this work, the thermal effect of a laser pulse is taken into account when mechanical-thermodiffusion (METD) waves are studied. The nonlocal semiconductor material is used when interference between holes and electrons occurs. The fractional technique is applied on the heat equation according to the photo-thermoelasticity theory. The governing equations describe the photo-excitation processes according to the overlapping between the thermoelasticity and photothermal theories. The thermoelastic deformation (TD) and the electronic deformation (ED) for the dimensionless fields are taken in one dimension (1D). The Laplace transforms are applied to obtain the analytical solutions when some initial and boundary conditions are applied at the nonlocal surface. The complete nondimensional solutions of the main quantities are obtained according to some numerical simulation approximate during the inversion processes of Laplace transforms and Fourier expansion. The time-fractional order, nonlocal, and thermal memories are used to compare the wave propagations of the main fields and are discussed graphically for nonlocal silicon material.

Elastic-thermal-diffusion model with a mechanical ramp type and variable thermal conductivity of electrons–holes semiconductor interaction

In this article, an elastic-thermodiffusion (ETD) model in the context of the coupled between the holes and electrons is constructed for the semiconductor material. The photothermal excitation in generalized thermoelasticity theory is used to describe this model. The governing equations are studied when the thermal conductivity is variable during the temperature graduation. The deformation occurrs in one-dimensional (1D) when thermoelastic (TD) and electronic(ED) transport processes are taken into consideration. The dimensionless field quantities are obtained analytically for the principle physical fields (hole charge field carrier, elastic, thermal, and electrons charge carrier density (plasma) waves). Laplace transform is used algebraically to solve the governing equations. When some conditions are taken at the boundary, the main physical fields are obtained and subjected to mechanical ramp type at rest. Laplace inverse with the approximate technique is used numerically during the transformation to get the closed-form in the time domain for the principle fields. Some comparisons are carried out graphically under the effect of variable thermal conductivity and thermal memories which are discussed for silicon material.

Response of thermal-optical-elastic waves of a rotator microstretch semiconductor media during photothermal transport processes

A novel theoretical mathematical-physical model for elastic semiconductor material is investigated when the microstretch properties of the medium are considered. During the photo-generated processes, the generalized thermoelasticity theory in photo-thermal theory is studied for excited semiconductor medium. The governing equations describe the coupled propagation of the elastic-thermal-plasma (optical) waves when the thermomicrostretch elastic semiconductor material is considered during a rotation field. The photo-thermal transport processes occur during a two-dimension (2D) of elastic and electronic deformation when the microinertia of microelement is considered. The harmonic wave method can obtain the main solutions for the basic physical variables. The complete analytical solutions of the considered variables are obtained when some mechanical-thermal and plasma conditions are applied on the boundary of the semiconductor medium. The numerical simulations of silicon (Si) and Germanium (Ge) media are constructed graphically with many comparisons according to new parameters with thermal memories and rotation parameters.

Hydrologic‐land surface modelling of the Canadian sporadic‐discontinuous permafrost: Initialization and uncertainty propagation

AbstractPermafrost thaw has been observed in recent decades in the Northern Hemisphere and is expected to accelerate with continued global warming. Predicting the future of permafrost requires proper representation of the interrelated surface/subsurface thermal and hydrologic regimes. Land surface models (LSMs) are well suited for such predictions, as they couple heat and water interactions across soil‐vegetation‐atmosphere interfaces and can be applied over large scales. LSMs, however, are challenged by the long‐term thermal and hydraulic memories of permafrost and the paucity of historical records to represent permafrost dynamics under transient climate conditions. In this study, we aim to understand better how LSMs function under different spin‐up states, which facilitates addressing the challenge of model initialization by characterizing the impact of initial climate conditions and initial soil frozen and liquid water contents on the simulation length required to reach equilibrium. Further, we quantify how the uncertainty in model initialization propagates to simulated permafrost dynamics. Modelling experiments are conducted with the Modélisation Environmentale Communautaire—Surface and Hydrology (MESH) framework and its embedded Canadian land surface scheme (CLASS). The study area is in the Liard River basin in the Northwest Territories of Canada with sporadic and discontinuous regions. Results show that uncertainty in model initialization controls various attributes of simulated permafrost, especially the active layer thickness, which could change by 0.5–1.5 m depending on the initial condition chosen. The least number of spin‐up cycles is achieved with near field capacity condition, but the number of cycles varies depending on the spin‐up year climate. We advise an extended spin‐up of 200–1000 cycles to ensure proper model initialization under different climatic conditions and initial soil moisture contents.

The memory time effects for unsteady seas and oceans water flow through the limestone porous medium in the presence of chemical reaction and Soret effects

AbstractIn this work, we study the effects of the thermal and diffusion memories in the seas and oceans water using the methodology of fractional calculus for modeling a viscous fluid. In our model, we derive a model with two fractional parameters representing the thermal and diffusion effects for this type of fluid. We formulate a problem of mixed convection heat and mass transfer flow of a viscous fluid through a Limestone porous medium in a vertical channel whose walls are kept at variable temperature and concentration. The influences of heat‐mass memories in the presence of chemical reaction, heat generation/absorption and, the Soret effect are discussed and represented graphically on all variables fields. Also, the influences of Darcy, Prandtl, Schmidt, Grashof parameters are compared with the effect of fractional parameters.

Functionally graded (FG) magneto-photo-thermoelastic semiconductor material with hyperbolic two-temperature theory

In this paper, a one-dimensional elastic–electronic deformation problem under the influence of the magnetic field will be inspected. Furthermore, the non-homogeneous (functionally graded) properties of semiconductor materials in the context of the photo-thermoelasticity theory will be studied. The hyperbolic two-temperature theory is taken into consideration during the photo-excited transport process. The interactions among the thermal, plasma, and elastic waves are analytically obtained when the optical and elastic parameters of the semiconductor medium are utilized as a function in the distance. The governing equations are formed using the Laplace transform technique to identify the analytical solutions of the key physical field distributions in the Laplace domain. Some thermal load, mechanical force, and plasma recombination conditions can be implemented at the free surface of the semiconductor medium. To illustrate the importance and effectiveness of the obtained results, the complete solutions of the main physical quantities in the space–time domain are identified using a numerical technique based on the inverse of the Laplace transform. Moreover, this work demonstrates the main physical field quantities that will be graphically represented and theoretically discussed. Many comparisons are made according to the influence of some parameters when thermal memories are taken into consideration.

Anomalous behavior induced by water insertion in molybdenum disulfide nanoflowers

The coexistence of negative photoconductivity and metallic-like behavior in conventional semiconductors is very uncommon. In this work, we report the existence of such unconventional physical properties in molybdenum disulfide nanoflowers (MoS2-NF). This is achieved by making the surface of MoS2 hygroscopic by alcohol treatment and creating a transport channel that favors protonic over electronic conduction. On cooling the MoS2-NF in a heat sink, the excess water that condenses on the surface forms a proton (H3O+) wire which exhibits pinched hysteresis characteristics. The conductivity of MoS2 increased by two orders of magnitude in the proton-dominated conduction regime with an exceptionally high positive temperature coefficient of 1.3 × 104 Ω K−1. Interestingly, MoS2-NF also exhibits strong negative photoconductivity at room temperature when illuminated with UV and infra-red radiation. This interesting behavior observed in MoS2 NF can be useful for energy harvesting applications and the realization of fast thermal memories and optical switches.

Magneto-Photo-Thermo-Microstretch Semiconductor Elastic Medium Due to Photothermal Transport Process

Electro-magnetic-thermal-microstretch elastic mathematical-physical model of semiconductor medium is investigated. The governing equations are studied in the context of photo-thermoelasticity theory during photothermal transport process. The semiconductor medium is exposed to an external magnetic field and a beam of laser. The coupled between electromagnetic field, thermal, elastic and plasma waves when the inertia-microstretch properties of elastic semiconductor material is taken into account. The main physical quantities are taken during two dimensions (2D) electronic-elastic deformation. The microinertia of microelement under the impact of external magnetic field is taken into consideration. The harmonic wave solutions in 2D with time variation is used to obtain the main physical fields. To obtain the complete solutions of the physical fields, some mechanical-thermal-elastic and plasma conditions for the semiconductor medium are taken at the boundary. The physical constants of the silicon (Si) material are used to make the numerical simulations and obtained the physical variables with the horizontal distance graphically. Many comparisons are made according to the thermal memories and the magnetic field influence.

Effect of rotation and magnetic field on a numerical-refined heat conduction in a semiconductor medium during photo-excitation processes

A novel model in photo-thermoelasticity theory is investigated in the paper understudy. The model is obtained theoretically for a semiconductor elastic medium, which is in a rotation case. The interaction between main physical quantities during photothermal transport process is expressed in the governing equations. In addition, the numerical-refined multi-phase-lags relaxation times (thermal memories) are studied in the context of the heat equation when the medium is exposed to an external magnetic field. Moreover, the harmonic wave method in two-dimensional (2D) is introduced during the coupling processes between multi-waves. As such, the complete exact solutions of the main physical fields of semi-infinite semiconductor medium are obtained. Some plasma, mechanical and thermal forces are applied at the outer surface of the elastic medium to determine the unknown parameters. Many comparisons are displayed graphically when the physical constants of silicon (Si) material are used. Theoretical results are discussed under the impact of magnetic field and rotation field.

Thermal-microstretch elastic semiconductor medium with rotation field during photothermal transport processes

A mathematical novel model for elastic semiconductor medium with microstretch properties is investigated. The generalized model is studied in the context of photo-thermoelasticity theory when the semiconductor medium is excited. The governing equations describe the coupled between the propagation of the elastic-thermal-plasma waves when the thermo-microstretch elastic semiconductor material is studied during a rotation field. The linear medium has an isotropic properties. The photothermal transport processes occurs during a two-dimension elastic and electronic deformation when the microinertia of microelement is taken into account. The harmonic wave method can be used to obtain the general solutions for the basic physical variables. The complete analytical solutions of the considered variables are obtained when some mechanical-thermal and plasma conditions are applied on the boundary of the semiconductor medium. The numerical simulations of silicon and germanium media are constructed graphically with many comparisons according to a new parameters with thermal memories and rotation parameter.

Solid-State Thermal Memory of Temperature-Responsive Polymer Induced by Hydrogen Bonds

Memory is an essential element for a computer to process information, which is integrated by logical circuits. Like electronic computing, thermal information can also be stored and read out by a thermal memory. Here, we show that a phase-changing polymer with hysteretic thermal transport properties can be experimentally processed into thermal memories at room temperature. We used a temperature-responsive and reversible polymer synthesized with melamine (M) and 6,7-dimethoxy-2,4[1H,3H]-quinazolinedione (Q) as a model system to demonstrate the manipulation of thermal transport at a molecular level. Fourier transform infrared spectroscopy and differential scanning calorimetry measurements indicate that this hysteretic behavior is based on the interaction of hydrogen bonds at high (317 K) and low (297 K) temperatures. This work demonstrates a controllable phonon transport process through the manipulation of hydrogen bonds, and thus it has potential applications in thermal memories.

Thermal conductivity changes of photo-elastic semiconductor excited in gravitational field with hydrostatic initial stress and internal heat source

In this work, the effect of hydrostatic initial stress is studied with the exited semiconductor material. Electrons are exited at the free surface of the elastic semiconductor medium using the photo-thermal-elastic theory during the transport (diffusion) process. The thermal memories are due to the dual-phase-lag (DPL) relaxation times of the heat conduction equation with a novel model. In this model, the thermal conductivity is chosen as a linear dependent function of the thermal temperature impact which is variable. The effect of gravitational field is taken into account during the two-dimensional (2D) elastic deformation under the impact of an internal heat source. The Kirchhoff transformation mapping is used. The harmonic wave (normal mode) method is applied for the 2D governing equations to obtain the main physical fields analytically. Some thermal and mechanical forces are applied with other elastic-plasma conditions at the free surface of the semiconductor material to get the complete solutions. Some comparisons used a novel parameters which depend on the DPL model and the differences in the thermal conductivity parameters and they are illustrated graphically and discussed.

Temperature dependent thermal conductivity during photothermal excitation process of semiconductor medium with an internal heat source in gravitational field

In this work, a novel model of semiconducting elastic material is studied during a process of photothermal excitation. The dual phase lag (DPL) for the heat conduction equation is introduced in the context of the variable of the thermal conductivity. The thermal conductivity can be chosen as a linear function of temperature (depend on temperature). The generalized thermoelasticy theory is investigated when an internal heat source is steady with a constant speed in the context of the gravitational field. The harmonic wave technique is used in two-dimensional deformations to obtain the considered physical fields. Some thermal loading subjected to thermal shock and other mechanical forces at the outer free surface of a semi-infinite elastic medium (semiconductor as silicon) are applied. The considered physical fields were illustrated graphically. The influences of some several variables are obtained which based on the DPL (thermal memories) model and the variable thermal conductivity. The results obtained are investigated and are depicted graphically.

Effect of gravity on a magneto-thermoelastic porous medium with the frame of a memory-dependent derivative in the context of the 3PHL model

The paper considers a 2D problem associated with a porous magneto-thermoelastic material under the effect of gravity in the context of the Three-Phase-Lag (3PHL) model and a 'memory dependent derivative frame. It has been assumed that during the initial stages, the medium is in an inactive state for the half-space (thermoelastic) the surface of this half-space is subjected to mechanical force and has a constant heat flux. The paper presents graphical illustrations of the variables under consideration as they vary along with the vertical distance. A number of figures are used to draw out several comparisons for the 'thermophysical quantities as they greatly assist in studying the effects of the gravity field, mechanical force, time, and thermal memories (relaxation times).