CN115752061B - Device and method for regulating and controlling heat radiation based on isotope engineering - Google Patents
Device and method for regulating and controlling heat radiation based on isotope engineering Download PDFInfo
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Abstract
The invention relates to a device and a method for regulating and controlling heat radiation based on isotope engineering, wherein the method can regulate and control the radiation heat transfer coefficient of a radiation heat flow modulation device, and the device comprises a first radiator and a second radiator which are oppositely arranged; wherein at least one of the first radiator and the second radiator has two or more stable isotopes; through the proportion design of different isotopes in the material, the film thickness monitoring is synchronously carried out on the growth of the radiator material, the optimal material composition and structural design are realized, namely the radiation heat flow modulation device based on isotope engineering regulation and control is prepared, and the radiation heat transfer coefficient is regulated. The method has wide application range, and the distance between the radiators can be in micro-nano level or macroscopic level; can enhance and inhibit heat radiation transmission, and has heat radiation regulation capacity of more than four orders of magnitude. By the scheme, heat management, heat energy utilization and regulation and control performances of the photoelectric device based on heat radiation are hopefully improved.
Description
Technical Field
The invention relates to the technical field of heat regulation and control, in particular to a device and a method for regulating and controlling heat radiation based on isotope engineering.
Background
Many elements have two or more stable isotopes, and materials of different isotopic composition may often exhibit different physical properties due to differences in mass and nuclear structure, particularly those closely related to crystal structure and lattice dynamics due to isotopic mass effects. Isotopes are therefore widely studied in many fields such as geochemistry, agriculture, medicine and thermal science.
On the one hand, isotope effects have evolved over several decades into two of the three basic modes of heat transfer—heat conduction and convection. However, the effect of isotopes on the third heat transfer mode (i.e., heat radiation) remains to be explored. Specifically, since the 60 s of the 20 th century, phonon scattering was reduced due to reduced atomic mass fluctuations, and the enhancement of phonon thermal conductivity by isotopic enrichment was observed by scholars through theoretical prediction and experiments. As the research on isotope-controlled crystal growth continues to be advanced, the technology is continuously innovated, and in recent years, scholars have measured isotope effects with thermal conductivity improvements exceeding 90% and 150% in bulk cubic boron nitride (cBN) and silicon nanowires, respectively. In addition, in the field of thermal convection, the influence of isotopes on fluid viscosity and fluid diffusivity has also been studied extensively. These isotope effects represent a great advantage in the fields related to heat conduction and convection. Thermal radiation is a ubiquitous heat transfer pathway, which is important in civilian aspects such as infrared detection; furthermore, in space exploration, heat radiation is the main channel of heat exchange between substances. However, at present, there is little research on whether isotope engineering can be used in the field of heat radiation.
In fact, for the radiator in the heat radiation transmission process, whether it is the optical phonon of the dielectric or the plasma of the metal or the semiconductor, the frequency and the broadening of the radiator are key characteristic parameters determining the radiation heat flow, and the isotope quality effect affects these key characteristic parameters mainly by changing the lattice structure and the lattice dynamics, so that the radiator has potential and extremely strong influence and wide application space.
In the second aspect, the current methods for heat radiation control with an order of magnitude improvement capability are mostly limited to the field of near-field heat radiation. However, the near-field heat radiation has a limited application range, the control requirement on the space between the radiators is extremely high, the small space difference can greatly weaken the heat radiation regulation and control performance, the robustness is weak, and the application range is narrow.
In the third aspect, although the scholars have made great efforts on heat radiation regulation and control at present, the heat radiation transmission capability obtained through parameterization research and design is greatly improved, most of optimized parameters are too ideal and lack physical feasibility. Because the material cannot accurately reach the designed physical properties in the preparation process, such as different isotope proportions and different thicknesses of the material, the heat radiation transmission capacity can be greatly influenced, the ideal parameter design can not reach the target performance in practical application, and the development of related devices is limited.
Disclosure of Invention
The invention aims to provide a device and a method for regulating and controlling heat radiation based on isotope engineering, according to the method, matching and mismatching of local electromagnetic state density characteristic peaks of a radiator material under different isotope ratios can be realized by regulating the isotope enrichment proportion in the radiator, and the heat radiation regulating and controlling capacity exceeding four orders of magnitude can be achieved.
To this end, in a first aspect, the present invention provides a method for adjusting and controlling a radiant heat transfer coefficient of a radiant heat flow modulation device, including providing a radiant heat flow modulation device, where the radiant heat flow modulation device includes a first radiator and a second radiator that are disposed opposite to each other; wherein the first radiator comprises a first material comprising a first element; the second radiator comprises a second material comprising a second element; wherein for at least one of the first material and the second material, surface polariton excitation is supported;
the regulation and control method comprises the following steps: and regulating and controlling the radiation heat transfer coefficient of the radiation heat flow regulating device by regulating the isotope abundance ratio in the first element and/or regulating the isotope abundance ratio in the second element.
Wherein, the surface polaritons may be surface phonon polaritons or surface plasmon polaritons. In the technical scheme of the invention, at least one side of the surface polaritons of the radiator can be thermally excited.
To uniformly describe the commonality of polaritons in the invention, the characteristic frequency omega of equivalent plasma polaritons is introduced p ，Wherein ε ∞ Is of high frequency dielectric constant omega TO And omega LO The transverse optical phonon frequency and the longitudinal optical phonon frequency are respectively positioned at the point gamma of the first Brillouin zone of the material; omega TO And omega TO The relative change of the reciprocal of the material reduced mass mu is in direct proportion to the relative change, which can be expressed as: /> For the binary elementThe material (AB) composed of the elements (A and B) has a reduced mass μ determined by the total mass of the individual elements: />Is the average atomic mass.
Wherein, for at least one of the first material and the second material, the heat flow regulating capacity (i.e. isotope effect eta) is more than 1000 by isotope engineering;
wherein, the liquid crystal display device comprises a liquid crystal display device,h max for maximum radiant heat transfer coefficient at different isotopic abundance ratios, h min Is the minimum radiant heat transfer coefficient at different isotopic abundance ratios.
According to the technical scheme of the invention, the radiation heat transfer coefficient of the radiation heat flow modulation device can be adjusted by adjusting the isotope abundance ratio of at least one element in at least one radiator material in the radiation heat flow modulation device.
The method for regulating and controlling the abundance ratio of different isotopes can be realized by controlling the conditions of precursors with different isotope ratios, ion beam flow rates of different source furnaces, temperature and the like in the growth of the radiator material, and can also be realized by an ion implantation and annealing treatment method after the material growth is finished.
According to the technical scheme of the invention, the isotope is a stable isotope. Those skilled in the art know that stable isotopes refer to isotopes that have no radioactivity or have a half-life of radioactivity greater than 1015 years.
In some embodiments, the first material and the second material are each independently selected from a polar dielectric, a metal, an intrinsic semiconductor, a doped semiconductor.
In some embodiments, the first material and the second material are each independently selected from the group consisting of: hydride dielectrics, e.g. lithium hydride 6 LiH, lithium deuteride 6 LiD), lithium tritide 7 LiT); boride dielectrics, e.g. cubesBoron nitride, hexagonal boron nitride; comprising an alloy of two or more selected from the group consisting of: zinc, gallium, selenium, indium, tin, tellurium, e.g. In 1-x Ga x As、GaAs 1-x-y N x Bi y 、Cu 2 ZnSnS 4 Etc.
In some embodiments, the first element and the second element are each independently selected from hydrogen, lithium, boron, carbon, nitrogen, oxygen, silicon, calcium, titanium, iron, nickel, copper, zinc, gallium, germanium, selenium, silver, indium, tin, antimony, tellurium.
In some embodiments, the first material and the second material are lithium hydride @ 6 LiH); the radiation heat transfer coefficient of the radiation heat flow modulation device is regulated and controlled by regulating the proportion of the isotope H/D of the hydrogen element in the lithium hydride in the first material and/or regulating the proportion of the isotope H/D of the hydrogen element in the lithium hydride in the second material.
In some embodiments, a vacuum is between the first and second radiators.
According to the technical scheme of the invention, the vacuum space between the first radiator and the second radiator is not limited to micro-nano magnitude, and is also applicable to macro-scale.
In some embodiments, the radiating structures of the first and second radiators are selected from the group consisting of: plate-plate, ball-plate; the thickness of the flat plate is less than 10 μm.
In some embodiments, the first and second radiators are the same thickness.
In some embodiments, the first and second radiators are radiators having a grating and/or a super surface structure.
According to the technical scheme of the invention, the radiant heat flow modulation device at least comprises the first radiator and the second radiator, and can also comprise more radiators, and the selection can be carried out by a person skilled in the art according to the use situation.
According to the technical scheme of the invention, the sizes of the first radiator and the second radiator can be selected according to actual requirements on the premise of processing feasibility; the thickness of the first and second radiators is preferably in the order of micro-nanometers.
In some embodiments, the thickness of the first and second radiators is selected to be 1 nanometer.
In some embodiments, the radiant heat flux modulating device wherein the first material and the second material have the same molecular formula, the first element and the second element are of the same elemental species.
In some embodiments, the modulation method increases the radiant heat transfer coefficient of the radiant heat flow modulation device, the modulation method comprising:
adjusting the ratio of isotopic abundance in the first element: the first element comprises a first isotope and a second isotope, and the mass number of the first isotope is larger than that of the second isotope; and adjusting the atomic number ratio of lighter isotopes in the variable isotope material of the first isotope and the second isotope to increase (or decrease) the reduced mass of the first radiator, and red-shifting (or blue-shifting) the characteristic frequency.
Adjusting the ratio of isotopic abundance in the second element: providing that the second element comprises a third isotope and a fourth isotope, the third isotope having a mass number greater than the fourth isotope; and adjusting the atomic number ratio of the third isotope to the fourth isotope to increase (or decrease) the reduced mass of the second radiator, and red-shifting (or blue-shifting) the characteristic frequency to enable the characteristic frequency to be close to (or far from) the first radiator.
In some embodiments, the modulation method increases the radiant heat transfer coefficient of the radiant heat flow modulation device, the modulation method comprising: the atomic number ratio of the first isotope to the second isotope is regulated to make the absolute value of the difference value of the atomic number ratio of the first isotope and the second isotope be 0; and/or adjusting the atomic number ratio of the third isotope to the fourth isotope to make the absolute value of the difference value of the atomic number ratio of the third isotope and the fourth isotope be 0; the characteristic frequencies of the first radiator and the second radiator are made to coincide (match).
In some embodiments, the modulation method reduces the radiant heat transfer coefficient of the radiant heat flow modulation device, the modulation method comprising:
adjusting the ratio of isotopic abundance in the first element: the first element comprises a first isotope and a second isotope, and the mass number of the first isotope is larger than that of the second isotope; adjusting the atomic number ratio of the first isotope to the second isotope, and increasing or setting the absolute value of the difference between the atomic number ratio of the first isotope and the atomic number ratio of the second isotope to 100%; and/or the number of the groups of groups,
adjusting the ratio of isotopic abundance in the second element: the second element comprises a third isotope and a fourth isotope, the mass number of the third isotope is larger than that of the fourth isotope, and the absolute value of the difference value of the atomic number ratio of the third isotope and the fourth isotope is 0; the method comprises the steps of carrying out a first treatment on the surface of the Adjusting the atomic number ratio of the third isotope to the fourth isotope to make the absolute value of the difference value of the atomic number ratio of the third isotope and the fourth isotope be 100%; the absolute values of the characteristic frequencies of the two radiators are made to differ maximally (mismatch).
In some embodiments, the first element is the same element species as the second element.
In some embodiments, among all isotopes in which the first element is present, the first isotope is the isotope having the largest mass number, and the second isotope is the isotope having the smallest mass number; and/or, among all isotopes in which the second element exists, the third isotope is the isotope with the largest mass number, and the fourth isotope is the isotope with the smallest mass number.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
(1) The invention firstly researches the isotope effect in the field of heat radiation, and reveals the great influence of isotopes on a third heat transfer mode (namely heat radiation). The invention utilizes the isotope to change the frequency and peak width of the optical phonon or plasma of the material, thereby changing the dielectric property and the local electromagnetic state density of the material, realizing the matching and the mismatching of the local electromagnetic state density characteristic peak of the radiator material under different isotope proportions, enhancing and inhibiting the heat radiation transmission, and realizing the heat radiation regulation and control of more than four orders of magnitude between radiators.
(2) The invention utilizes the heat radiation heat exchange principle, is not limited to near-field heat radiation or far-field heat radiation, can realize heat radiation regulation and control capability exceeding four orders of magnitude in both the near-field range and the far-field range, embodies the flexibility of the application scene of the invention, and greatly expands the application space and range of the invention.
(3) According to the invention, the material physical properties corresponding to the actual parameter range between the radiators can be considered according to the practical application conditions, and the target isotope ratio growth material can be flexibly selected so as to achieve the target characteristic parameters and realize the maximum or minimum heat radiation transfer between the radiators. In addition, the device and the method for regulating and controlling the heat radiation based on the isotope engineering are practical, and even if the characteristic size or the distance between the radiators is controlled to be 1 order of magnitude difference in the material growth, the heat radiation regulation and control of several orders of magnitude can be realized. The robustness and wide applicability of the device and the method for regulating and controlling the heat radiation based on the isotope engineering are illustrated.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. In the drawings:
FIG. 1 is a schematic diagram and schematic diagram of a device for regulating and controlling heat radiation based on isotope engineering;
FIG. 2 is a graph showing the relationship between the optical phonon at the Γ point of the first Brillouin zone of lithium hydride and the reduced mass;
FIG. 3 shows the effect of isotopic ratio variation on the real and imaginary parts of the dielectric constant of lithium hydride in example 1;
FIG. 4 is the effect of isotope ratio variation on the electromagnetic local density of states (LDOS) at 100nm on the surface of bulk lithium hydride in example 1;
FIG. 5 is the variation of the radiative heat transfer coefficient and isotope effect with the distance for the symmetric material combinations with different isotope ratios in example 1;
FIG. 6 is the variation of radiative heat transfer coefficient, isotope effect with spacing for asymmetric material combinations with different isotope ratios in example 2;
FIG. 7 is a graph showing the isotopic effects as a function of film thickness and emitter spacing dimensions for thin film lithium hydride in example 3;
fig. 8 shows the variation of the isotope effect of the radiator material with different characteristic frequencies of the surface wave and the variation of the reduced mass due to the isotope at different temperatures in example 4.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
In order to achieve the aim of greatly regulating and controlling the heat radiation in the range from micro-nano scale to macro-scale, the invention provides a device and a method capable of regulating and controlling the radiation heat by crossing four orders of magnitude based on isotope engineering after the isotope effect in the heat radiation field is researched. The physical mechanism by which it works is briefly set forth herein:
because of different isotope proportions, the mass of the crystal changes along with the change of the mass distribution, so that the vibration characteristic of the crystal lattice is influenced, and the response capability (namely dielectric function) of the crystal to the change of an external electromagnetic field is further influenced. Taking a typical polar dielectric material XY as an example, the relationship between the optical phonon and the dielectric function of the point Γ in the first brillouin zone can be described by a lorentz oscillator model:
wherein, epsilon in the formula ∞ Is high-frequency dielectric constant, Γ is damping factor, ω TO And omega LO The transverse optical phonon frequency and the longitudinal optical phonon frequency are respectively located at the point Γ of the first brillouin zone of the material.
If X has two isotopes, X 'and X', respectively. Transverse optical phonon omega in material TO And longitudinal optical phonon ω LO Has a close relationship with its reduced mass. With X in XY 2 The characteristic oscillation frequency of the optical phonon increases with the increase of the square root of the reciprocal of the mass of the XY reduction, and is expressed as follows:wherein X is f X' is the molecular formula of XY composed of f, X 1 Is an XY crystal with a purity of 100% X'. />Is the reciprocal of the material XY reduced mass μ, +.>Is the average mass of atoms, f i Is the ratio of certain isotopes.
When the heavy isotope is replaced with the light isotope, the optical phonon frequency at the region center Γ point of the first brillouin zone increases. Since these phonons are collective oscillations of atoms produced by specific arrangements and chemical bonds, the bonding strength between atoms is altered by the lighter mass of the constituent atoms, similar to the mass-spring oscillator model. Meanwhile, phonons undergo multiple scattering such as phonon-phonon scattering, boundary scattering, and isotope-phonon scattering. In crystals composed of different isotopes, the crystal non-harmony is enhanced and the phonon linewidth is widened due to more chaotic mass distribution. In general, phonon lifetime of an equal-proportion mixed crystal is most severely limited by phonon isotope scattering, and can be estimated by using the quality fluctuation parameters given by Slack:
(reference, G.A. Slack, effect of Isotopes on Low-Temperature Thermal Conductivity [ J ], physical Review 105,1957,829)
Wherein, the liquid crystal display device comprises a liquid crystal display device,is the quality fluctuation parameter of a single element. If the isotope of Y is not considered, then X consisting of equal proportions of X 'and X' is present 0.5 Y shows the strongest mass disorder, and its damping factor Γ reaches a maximum value, since the damping coefficient Γ in the lorentz oscillator model is inversely proportional to phonon lifetime.
The dielectric response of a material determines the radiation properties of the material according to the fluctuation dissipation theorem. When an incident photon is coupled with lattice vibrations, surface waves occur in a frequency band with a negative dielectric constant, including: surface phonon polaritons (SPhPs, polar dielectric support) or surface plasmon polaritons (SPPs, metal or doped semiconductor support). Based on wave electrodynamics, the heat radiation transfer coefficient between two half infinite parallel planar radiators can be expressed as:
the radiation heat transfer coefficient is only equal to the transmission coefficient tau of s-and p-polarization when the temperature and the interval distance of the radiator are determined s (ω,k)、τ p (ω, k) are the main factors of phonon frequency shift and broadening effects caused by isotopes.
Once the surface wave can be thermally excited, if the radiation emitter is close to the radiation receiver, the thermal radiation will be significantly enhanced due to photon tunneling effects, with quasi-monochromaticity, which may exceed the blackbody radiation limit by several orders of magnitude. On the other hand, even if the radiation emitter is far away from the radiation receiver, the surface wave has no dominant effect, and at this time, the energy dissipation of the electromagnetic field in the film in the far field can be controlled by controlling the frequency and the broadening of the optical phonon, which is embodied as the main contribution of the leakage mode represented by the Berreman mode, so that the heat radiation is efficiently regulated and controlled. Therefore, the invention can control the electromagnetic field energy loss of the surface wave and the far field of the material by the influence of isotopes on the optical phonon frequency and the broadening, and provides a method and a device for regulating and controlling the heat radiation based on isotope engineering.
Through the isotope effect research in the heat radiation field, the invention can change the frequency and peak width of the optical phonon or plasma of the material by utilizing isotopes, thereby changing the dielectric property and the local electromagnetic state density of the material; the radiation heat transfer performance between the same materials can be enhanced by one order of magnitude or more on one hand by matching and mismatching the local electromagnetic state density between the characteristic peak radiators without limiting the distance between the radiators; on the other hand, the principle of isotope effect in the invention can be utilized to realize that the radiation heat transfer performance among the same materials is reduced by four orders of magnitude, as shown in the schematic diagram of fig. 1.
Specifically, polar dielectric materials or metal materials which are composed of two or more isotopes and support surface wave excitation are selected as one of the radiators, according to the frequency shift and broadening effects of the frequency and peak width of optical phonons or plasmas in the selected radiator materials along with the abundance of a specific isotope in the materials, isotope proportions in different materials are realized through isotope engineering, the reduction quality of the materials is changed, the resonance frequency of the surface optical phonons of the materials is controlled, and therefore matching and mismatch of the local electromagnetic state density of the materials are realized, and opening and suppression of a radiation heat flow channel are realized. Meanwhile, the mode contribution (near field: frustrated mode due to frustrated total internal reflection; far field: interference mode in the Fabry-Perot cavity due to thin film material) of the non-surface wave section can be suppressed by controlling the size of the radiator, so that the radiation heat flow regulation and control of more than four orders of magnitude is realized.
In some embodiments, a radiant heat flux modulation unit comprising a first radiator and a second radiator having parallel plate-to-plate structures is subject to modulation of a radiant heat transfer coefficient. If the heat radiation between the radiators needs to be enhanced, the molecular formula and the isotope ratio of the two radiator materials are the same through regulation and control, and the isotope ratio with the largest mass fluctuation is selected, namely, the isotope with the smallest mass number and the isotope with the largest mass number in the variable isotope elements of the materials respectively account for 50 percent.
In some embodiments, a radiant heat flux modulation unit comprising a first radiator and a second radiator having parallel plate-to-plate structures is subject to modulation of a radiant heat transfer coefficient. If the heat radiation between the weak radiators is needed, the molecular formulas of the two heat radiation flat plate materials are the same through regulation and control, and the isotope proportions are different. One of the radiator materials consists of 100% of the isotope with the smallest mass number, and the other radiator material consists of 100% of the isotope with the largest mass number.
Hereinafter, the present invention will be described with reference to the foregoing physical mechanisms, and embodiments thereof, to illustrate specific implementations of an apparatus and method for modulating thermal radiation based on isotope engineering.
In the present invention, unless otherwise specified, d denotes the spacing between the radiators, f denotes the proportion of a particular isotope in the material to all of the elements, and the proportion of isotopes in the elements refers to the proportion of the number of lighter isotope atoms in the variable isotope material.
Example 1
The radiant heat flow modulation device comprises a first radiator and a second radiator which are oppositely arranged, wherein the first radiator and the second radiator are of flat plate structures and are semi-infinite blocks relative to a vacuum space, and the space is 100nm; the materials of the first radiator and the second radiator are lithium hydride; the temperature T is set to 300K. This example adjusts the radiative heat transfer coefficient of lithium hydride by varying the isotopic ratio of lithium and hydrogen elements.
Lithium hydride is a polar dielectric material supporting surface phonon polariton excitation, a property that can greatly enhance heat radiation. The lithium element has 6 Li and Li 7 Li two stable isotopes, hydrogen element having 1 H、 2 D and 3 t three isotopes, but 3 T is a radioactive element. However, in this embodiment, we consider only the real feasibility 1 H and 2 two stable isotopes of D. Lithium element in lithium hydride as radiator material is composed of 6 Li and Li 7 Li composition, wherein 6 The ratio of Li to Li element is f 1 The ratio of H to hydrogen element is f 2 Will have a different f 1 And f 2 The values of lithium hydride are shown below: 6 LiH(f 1 ＝100％,f 2 ＝100％)， 6 LiD(f 1 ＝100％,f 2 ＝0)， 6 Li eq H(f 1 ＝100％,f 2 ＝50％)， 7 LiH(f 1 ＝0,f 2 ＝100％)， 7 LiD(f 1 ＝0,f 2 ＝0)， 7 Li eq H(f 1 ＝0,f 2 ＝50％)。
firstly, researching the influence of isotopes on optical phonons of gamma point of a first Brillouin zone of lithium hydride, and negative power mu of phonon frequency along with reduced mass under different isotopic abundance compositions -0.5 The results of (2) are shown in FIG. 2. Under the influence shown in fig. 2, the lorentz oscillator model is introduced, and the real and imaginary parts of the dielectric constants of six typical lithium hydrides are shown in fig. 3 (left) and fig. 3 (right).
The electromagnetic local state densities at the height of 100nm of the six semi-infinite lithium hydride surfaces are shown in FIG. 4. Since the electromagnetic local state density of the material can represent the intensity of the radiation capability of the material, the radiation capability of a single radiator can be obviously influenced by controlling the isotope ratio of lithium and hydrogen elements in lithium hydride. The more lightweight isotopes in the material, the more the material's radiation capacity shifts to high frequencies. It has also been found that the absolute value of the difference decreases with different isotope ratios (i.e. |f 1 -f 2 I decrease), i.e. mass fluctuations in the material increase, the phonon broadening of the material will result in a decrease of the peak of the local state density, which also affects the radiation capacity of the radiator.
For the pure 6 Li-composed thermal radiation control device, three pairs with typically different isotopic abundances are consideredHeat radiation regulating and controlling devices with a structure are respectively 6 LiH- 6 LiH、 6 Li eq H- 6 Li eq H and 6 LiD- 6 LiD. Wherein both sides of "-" show materials of the first radiator and the second radiator in the heat radiation regulating device, respectively. The change of the radiation heat transfer coefficient and isotope effect of the three heat radiation control devices along with the distance is shown in fig. 5. According to the results of figure 5, 6 LiH- 6 the LiH radiation heat transfer coefficient is the smallest, 6 Li eq H- 6 Li eq the radiation heat transfer coefficient of H is the largest 6 LiH- 6 2.4 times LiH.
For the pure 1 The heat radiation regulating device composed of H is considered to be three symmetrical heat radiation regulating devices with typical different isotope abundances, which are respectively 7 LiH- 7 LiH、 eq LiH- eq LiH (LiH) 7 LiD- 7 LiD. The change of the radiation heat transfer coefficient and isotope effect of the three heat radiation control devices along with the distance is also shown in fig. 6. According to the results of figure 5, 7 LiH- 7 the LiH radiation heat transfer coefficient is the smallest, 7 Li eq H- 7 Li eq the radiation heat transfer coefficient of H is the largest 7 LiH- 7 LiH 0.73 times.
According to the technical proposal provided by the invention, 6 Li eq H- 6 Li eq h is compared with other two heat radiation devices 6 LiH- 6 LiH (LiH) 6 LiD- 6 LiD, wherein the absolute value of the difference between the H and D ratios in the hydrogen element is |100% -0% |=100%), and the heat radiation device is prepared by reducing the difference between the H and D ratios in the hydrogen element 6 Li eq H- 6 Li eq H (the absolute value of the difference between the H and D ratios in the hydrogen element is |50% -50% |=0%), in each of the two radiators, the radiation heat transfer coefficient of the device is significantly improved, which is mainly derived from the broadening effect of isotopes related to material quality fluctuation.
In the same way, the processing method comprises the steps of, eq LiH- eq LiH is compared with other two heat radiation devices 7 LiH- 7 LiH (LiH) 7 LiD- 7 LiD, of two radiators of LiD, of lithium element 6 Li and Li 7 The absolute value of the difference in Li duty ratio is |100% -0% |=100%), by reducing the amount of lithium element 6 Li and Li 7 Li ratio difference, and heat radiation device prepared eq LiH- eq LiH (of two radiators of which each is lithium element 6 Li and Li 7 The absolute value of the difference of the Li ratio is |50% -50% |=0%), and the radiation heat transfer coefficient of the device is remarkably improved.
Example 2
The radiant heat flow modulation device comprises a first radiator and a second radiator which are oppositely arranged, wherein the first radiator and the second radiator are of flat plate structures and are semi-infinite blocks relative to a vacuum space, and the space is 100nm; the materials of the first radiator and the second radiator are lithium hydride; the temperature T is set to 300K. Unlike embodiment 1, this embodiment mainly considers the asymmetric situation where the two radiator elements are not identical in composition, one radiator material is fixed as 6 LiH (i.e. f 1 =100%) by changing another isotopically engineered lithium hydride 6 Li eng H) The H/D ratio of the medium hydrogen element isotope adjusts the radiation heat transfer coefficient.
For simplicity of representation, will have different H/D ratios 6 Li eng H is represented as follows: liH 100% H, li eq H50%, liD 0%. Three heat radiation regulating and controlling devices with different isotope abundances are respectively LiH-LiH and LiH-Li eq H and LiH-Li eq D. Wherein both sides of "-" show materials of the first radiator and the second radiator in the heat radiation regulating device, respectively.
The change of the radiant heat transfer coefficient and isotope effect of the three radiant heat flow modulation devices along with the distance is shown in fig. 7. At a vacuum interval of 1nm, the radiation heat transfer coefficient of LiH-LiH is the maximum, and is LiH-Li eq 57.5 times D.
According to the technical scheme provided by the invention, compared with a thermal radiation regulating device LiH-LiH (the ratio of H in each of two radiators is larger than that of D), lithium hydride is regulatedThe difference between the H and D duty ratios is used for preparing the thermal radiation regulating and controlling device LiH-Li eq D (the duty ratio of H in the first radiator is larger than that of D, the absolute value of the difference between the two is 100 percent), and the duty ratio of D in the second radiator is larger than that of H, and the absolute value of the difference between the two is 100 percent). It can be seen that the radiative heat transfer coefficient is reduced by one order of magnitude using isotope engineering.
Example 3
Providing a radiant heat flow modulation device, which consists of a first radiator and a second radiator which are oppositely arranged, wherein the first radiator and the second radiator are of a thin film structure; the materials of the first radiator and the second radiator are lithium hydride; the temperature T is set to 300K. This example demonstrates that, on the basis of example 2, when the spacing between the first radiator and the second radiator is different for the radiator of the thin film structure, the isotopic effect of the hydrogen element in LiH can still be adjusted by changing the isotopic ratio thereof, so as to adjust the radiant heat transfer coefficient.
Two kinds of heat radiation regulating and controlling devices with different hydrogen isotope abundance are respectively LiD-LiD and LiH-LiD. Wherein both sides of "-" show materials of the first radiator and the second radiator in the heat radiation regulating device, respectively.
The radiator in this embodiment is a thin film structure, on the one hand, unlike embodiment 1 in which frustration mode is dominant due to frustrated total internal reflection in the whole spectrum, as the radiator material is thinned, it can be obtained from the local electromagnetic state density (LDOS) feature in fig. 4, and the LDOS of the thin film material outside the surface wave frequency band is greatly reduced and is more and more similar to the vacuum feature. At this time, the contribution of the SPhPs coupling between the films gradually takes over the frustrated mode dominant radiative heat flow. Under the condition of narrow LDOS distribution, even if the frequency shift caused by the change of isotope proportion is very tiny, serious mismatch of SPhPs coupling can be caused, and the transmission probability of asymmetric material combination is greatly reduced.
On the other hand, unlike the single dispersion relationship formed by bulk materials at the bulk-vacuum interface, thin films can be split into two dispersion relationships of symmetric and anti-symmetric modes by interlayer SPhPs coupling.
When the spacing between the first radiator and the second radiator is a near field vacuum spacing (e.g., 1 nm), the splitting of the dispersion relationship can be combined into a single dispersion relationship at the bulk-vacuum interface at the separation site supporting the large wave vector, at which point the heat radiation characteristics in example 1 can be recovered.
When the distance between the first radiator and the second radiator is further increased (e.g. 1 μm), the split two SPhPs modes are difficult to combine due to insufficient magnitude of the wave vector supported in the vacuum space, and the two modes are separated into two main contributions located near the two optical phonon frequencies by the coupling of the radiators, so that the thermal radiation transfer channels are more mismatched, i.e. a larger isotope effect is generated.
Fig. 7 shows the isotopic effect as a function of the thickness of the radiator material at a distance representative of the near field thermal radiation range and far field thermal radiation. Specifically, the present invention relates to a method for manufacturing a semiconductor device. Example 3 compares the case of 1nm, 10nm, 100nm, 1 μm and semi-infinite blocks.
As can be seen from fig. 7, the maximum isotope effect obtained for a 1nm LiH film can be two orders of magnitude greater than that for a bulk LiH, i.e., the heat radiation transfer coefficient can be reduced by three orders of magnitude by isotope engineering at this time. The interval of the magnetic shoe showing the huge isotope effect is in the hundred-nanometer range, which brings new radiation control possibility for experiments and devices of hundred-nanometer magnitude. Meanwhile, in order to achieve a more remarkable isotope effect, the plate should be smaller than 10 μm.
The above results show that the isotope effect at different vacuum gap sizes is not monotonically changing, but there is a fluctuation in a certain range due to the trade-off variation between different dominant modes. Wherein, for near field thermal radiation, the frustrated mode gradually masks the contribution of the SPhPs mode due to the increased radiator thickness; for far-field thermal radiation, the interference mode gradually replaces the strong absorption of electromagnetic field energy by optical phonons through a similar leakage mode.
This embodiment also demonstrates that for a thin film structured radiator, when the spacing of the first and second radiators is different, the isotope effect can still be adjusted by changing the ratio of isotopes in the radiator material, thereby adjusting the radiative heat transfer coefficient.
Example 4
In order to further explain the radiator materials applicable to the technical scheme of the invention, the common characteristics of different materials supporting the surface wave are extracted, and the Lorentz-Du Lude model is utilized to effectively represent the characteristic frequency of the surface wave by using the equivalent plasma frequency, so that the specific influence of two most important parameters on the radiation heat flow regulation and control in isotope engineering is obtained through analysis. The method comprises the following steps:
the lorentz-Du Lude model can be expressed as:
the surface equivalent plasma frequency of the material isWhen omega TO When=0, the lorentz-Du Lude model can be simplified to Du Lude model. For simplicity, this example uses the LST relationship +.>Assume ε ∞ ＝1，ε 0 =0, and Γ is fixed at 2cm -1 Let r=ω LO /ω TO Fixed at 1.8, there is
When the two radiators are in a parallel plate structure, the average temperature is 300K, the vacuum interval between the two radiators is 100nm, and the radiators are all films with the thickness of 1 nm. In this case, the present example clearly reveals the change in reduced mass of the material due to isotopic variationThe bigger the isotope effect the bigger this rule is, as shown in fig. 8.
According to FIG. 8, at 300K, when Ω p The frequency is greater than the near infrared region (omega p >9000cm -1 ) The isotope effect is smaller than 1, and corresponds to the situation that the surface wave of the material cannot be excited, in this case, the radiant heat flow cannot be effectively applied to the technical scheme provided by the invention, and is regulated and controlled through isotope engineering.
This embodiment is further focused on that the excitation of the surface wave of material is temperature dependent. In the equivalent plasma frequency range in which the radiant heat flow can be effectively regulated and controlled at 300K, an optimal omega exists p (i.e. Ω p,opt ) Its isotopic effect is greatest. At Ω p,opt The occurrence of the maximum isotope effect at the frequency mainly comes from the result of the maximum difference of surface wave coupling in the radiator combination with the same isotope ratio at two sides and the radiator combination with different isotope ratios at two sides in the near-field heat radiation interval range of the material. Further, since temperature will affect the excitation of the surface wave, other conditions are kept unchanged at different temperatures, the optimal material resonance frequency Ω p,opt The values will also be different. For example, at 300K, Ω p,opt About 2800cm -1 Omega at 50K p,opt About 500cm -1 。
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (12)
1. The method for regulating and controlling the radiation heat transfer coefficient of the radiation heat flow modulation device is characterized by comprising the steps of providing a radiation heat flow modulation device, wherein the radiation heat flow modulation device comprises a first radiator and a second radiator which are oppositely arranged; wherein the first radiator comprises a first material comprising a first element; the second radiator comprises a second material comprising a second element; wherein for at least one of the first material and the second material, surface polariton excitation is supported;
the regulation and control method comprises the following steps: by adjusting the ratio of isotopic abundance in the first element and/or adjusting the ratio of isotopic abundance in the second element; the radiation heat flow modulation device based on isotope engineering regulation and control is prepared.
2. The conditioning method of claim 1, wherein the first material and the second material are each independently selected from the group consisting of a polar dielectric, a metal, an intrinsic semiconductor, a doped semiconductor.
3. The conditioning method of claim 1, wherein the first material and the second material are each independently selected from the group consisting of: hydride dielectrics, boride dielectrics, and alloys; the alloy includes two or more selected from the group consisting of: zinc, gallium, selenium, indium, tin, tellurium.
4. The conditioning method of claim 1, wherein the first element and the second element are each independently selected from the group consisting of hydrogen, lithium, boron, carbon, nitrogen, oxygen, silicon, calcium, titanium, iron, nickel, copper, zinc, gallium, germanium, selenium, silver, indium, tin, antimony, tellurium.
5. The method of modulating according to claim 1, wherein a vacuum is between the first radiator and the second radiator.
6. The modulation method of claim 1, wherein the radiating structures of the first and second radiators are selected from the group consisting of: plate-plate, ball-plate; the thickness of the flat plate is less than 10 μm.
7. The tuning method of claim 1, wherein the first radiator and the second radiator have the same thickness.
8. The tuning method of claim 1, wherein the first and second radiators are radiators with a grating and/or a super surface structure.
9. The method of claim 1, wherein the first material and the second material have the same molecular formula, and the first element and the second element have the same element species.
10. The modulation method of any one of claims 1-9, wherein the modulation method increases the radiant heat transfer coefficient of the radiant heat flow modulation device, the modulation method comprising:
adjusting the ratio of a first isotope of the first element to a second isotope in the first radiator, the first isotope having a mass number greater than the relative atomic mass of the second isotope; adjusting the ratio of the molecular numbers of the first isotope and the second isotope to increase the reduced mass of the first radiator, the characteristic frequency is red shifted,
adjusting the ratio of a third isotope of the second element to a fourth isotope in the second radiator, the third isotope having a mass number greater than the relative atomic mass of the fourth isotope; and adjusting the molecular number ratio of the third isotope to the fourth isotope to increase the reduced mass of the second radiator, and red-shifting the characteristic frequency to enable the characteristic frequency to be close to the first radiator.
11. The modulation method of any one of claims 1-9, wherein the modulation method reduces the radiant heat transfer coefficient of the radiant heat flow modulation device, the modulation method comprising:
adjusting the ratio of a first isotope of the first element to a second isotope in the first radiator, the first isotope having a mass number greater than the relative atomic mass of the second isotope; adjusting the molecular number ratio of the first isotope to the second isotope to reduce the reduced mass of the first radiator, blue shift the characteristic frequency,
adjusting the ratio of a third isotope of the second element to a fourth isotope in the second radiator, the third isotope having a mass number greater than the relative atomic mass of the fourth isotope; and adjusting the molecular number ratio of the third isotope to the fourth isotope to reduce the reduced mass of the second radiator, and blue-shifting the characteristic frequency to enable the characteristic frequency to be far away from the first radiator.
12. The method of modulation of any one of claims 1-9, wherein the method of modulation of the ratio of isotopic abundance is achieved by a method selected from the group consisting of: precursors with different isotope ratios are controlled in the growth of the radiator material, ion beam flow rates and/or temperatures of different source furnaces are adopted, and ion implantation and annealing treatment are carried out after the growth of the material is finished.
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| TW201338226A (en) * | 2012-01-20 | 2013-09-16 | Yao Cheng | Magneto-electric effect material and its manufacturing method |
| CN109405625A (en) * | 2018-09-11 | 2019-03-01 | 上海交通大学 | Near field thermal radiation system and preparation method thereof |
| CN112794719A (en) * | 2021-01-05 | 2021-05-14 | 中国科学院上海硅酸盐研究所 | Normal pressure sintered anti-irradiation silicon carbide ceramic material and preparation method thereof |
| CN114877741A (en) * | 2022-05-12 | 2022-08-09 | 苏州大学 | Heat flow regulation and control device based on near-field thermal radiation |
| CN114975179A (en) * | 2022-05-23 | 2022-08-30 | 清华大学 | Radiation heat flow regulation and control device based on semiconductor micro-nano array structure and application thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| TW201338226A (en) * | 2012-01-20 | 2013-09-16 | Yao Cheng | Magneto-electric effect material and its manufacturing method |
| CN109405625A (en) * | 2018-09-11 | 2019-03-01 | 上海交通大学 | Near field thermal radiation system and preparation method thereof |
| CN112794719A (en) * | 2021-01-05 | 2021-05-14 | 中国科学院上海硅酸盐研究所 | Normal pressure sintered anti-irradiation silicon carbide ceramic material and preparation method thereof |
| CN114877741A (en) * | 2022-05-12 | 2022-08-09 | 苏州大学 | Heat flow regulation and control device based on near-field thermal radiation |
| CN114975179A (en) * | 2022-05-23 | 2022-08-30 | 清华大学 | Radiation heat flow regulation and control device based on semiconductor micro-nano array structure and application thereof |
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