A structure for regulating near-field radiation heat transfer based on hyperbolic material

Abstract

This invention relates to the field of radiation heat transfer modulation devices, specifically to a structure for modulating near-field radiation heat transfer based on hyperbolic materials. The structure includes a substrate and nanoparticles, specifically MoO3 particles, disposed on the substrate. The substrate is made of MoO3. The hyperbolic polarized particle (HVPP) excited by the substrate provides an anisotropic heat transfer channel for inter-particle radiation heat transfer. The radiation heat transfer between MoO3 particles is modulated by rotating the substrate. This invention utilizes HVPP to establish an anisotropic radiation heat transfer channel and modulates near-field radiation heat transfer between particles by rotating the substrate. It was found that the excitation energy of HVPP in the substrate significantly enhances radiation heat transfer.

Description

Technical Field

[0001] This invention relates to the field of radiation heat transfer control devices, and in particular to a structure for controlling near-field radiation heat transfer based on hyperbolic materials. Background Technology

[0002] Near-field radiative heat transfer has wide applications in many fields due to its heat transfer capacity, which far exceeds the blackbody radiation limit, such as thermoelectric photoelectric, thermal imaging, heat-assisted magnetic recording, radiative cooling, and thermal management. To further enhance radiative heat transfer, attention has turned to hyperbolic materials. Hyperbolic materials possess very high interfacial photon states density, and their hyperbolic dispersion properties support the free propagation of evanescent wave photons in free space within them, making them highly promising for near-field heat transfer applications.

[0003] Previous studies have shown that the main factors affecting near-field radiative heat transfer in hyperbolic materials are surface modes and bulk modes. Bulk modes describe the propagating waves within hyperbolic materials and can support large wave vector propagation, attracting widespread attention. In 2012, Biehs et al. demonstrated that the excitation of hyperbolic bulk modes can greatly enhance near-field radiative heat transfer between hyperbolic materials, and termed them hyperbolic phonons (HPP) [S. Biehs, et al., Physical Review Letters 109, 104301 (2012).]. Due to their bulk characteristics, these hyperbolic phonons were termed hyperbolic bulk phonons (HVPP) by Wu et al., who also described the excitation range of HVPP and hyperbolic surface phonons (HSPP), providing important guidance for subsequent research on HVPP and HSPP [X. Wu et al., Journal of Quantitative Spectroscopy and Radiative Transfer 258, 107337 (2021).]. In recent years, Zhao et al. have used HVPP to enhance near-field radiative heat transfer between plates based on natural hyperbolic materials and hyperbolic metamaterials [B. Zhao et al., Journal of Heat Transfer 139, 022701 (2017).]. Zhang et al. proposed to use the excitation of HSPP in anisotropic metasurfaces to achieve the effect of controlling interparticle radiative heat transfer [Y. Zhang, M. et al., Physical Review B 100, 085426 (2019).]. However, the mechanism of controlling near-field radiation by utilizing the orientation dependence and discreteness of HVPP needs further in-depth research. Summary of the Invention

[0004] In view of this, the purpose of this invention is to propose a structure for regulating near-field radiation heat transfer based on hyperbolic materials, so as to solve the problem that the existing technology cannot utilize the direction dependence and discreteness of HVPP to regulate near-field radiation.

[0005] To achieve the above objectives, the present invention provides a structure for regulating near-field radiative heat transfer based on hyperbolic materials, comprising a substrate, and further comprising nanoparticles disposed on the substrate, wherein the nanoparticles are MoO3 particles, the substrate is made of MoO3, and the HVPP excited by the substrate provides anisotropic heat transfer channels for interparticle radiative heat transfer, and the interparticle radiative heat transfer is regulated by rotating the substrate.

[0006] The overall dimensions of the structure are on the order of 0.5*0.5*0.1cm.

[0007] Preferably, there are two MoO3 particles, the distance d between the two MoO3 particles is 300-1800 nm, and the radius of the MoO3 particles is 10 nm.

[0008] Preferably, the thickness of the substrate is 100-1000 nm.

[0009] The substrate is mounted on the base plate via a linkage, and the MoO3 particles are suspended below the fixed plate via a cantilever beam, with the fixed plate positioned above the substrate.

[0010] As an optional implementation, the linkage is a knob. The substrate is connected to the base plate via a knob, and the rotation of the base plate drives the rotation of the substrate, thereby changing the radiative heat transfer.

[0011] The excitation mode can be modulated by changing the three crystal orientations perpendicular to the MoO3 substrate on the substrate surface.

[0012] The excitation modes include excitation on the left and right sides of the origin, excitation on the top and bottom sides, and excitation at various angles within the plane.

[0013] The modulation effect produced by HVPP excitation was demonstrated by changing the interparticle spacing and substrate thickness.

[0014] When the interparticle spacing is small and the substrate thickness is thin, the radiative heat transfer between particles is large; when the interparticle spacing is large and the substrate thickness is thin, the radiative heat transfer between particles will generate more peaks during the substrate rotation process.

[0015] The beneficial effects of this invention are:

[0016] (1) This invention proposes a structure based on hyperbolic material to regulate near-field radiation heat transfer. An anisotropic radiation heat transfer channel is established using HVPP. Near-field radiation heat transfer between particles is regulated by rotating the substrate. It is found that the excitation energy of HVPP in the substrate significantly enhances radiation heat transfer.

[0017] (2) This invention fills the gap in the study of the mechanism of near-field radiation regulation by utilizing the direction dependence and discreteness of HVPP, and can provide theoretical guidance for near-field radiation thermal regulation.

[0018] (3) This invention further demonstrates the modulation effect produced by HVPP excitation by changing the particle spacing and substrate thickness: when the particle spacing is small and the substrate thickness is thin, the radiative heat transfer between particles is large; when the particle spacing is large and the substrate thickness is thin, the radiative heat transfer between particles will generate more peaks during substrate rotation. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of the present invention; wherein, the arrows represent the heat transfer process;

[0021] Figure 2 The three crystal orientations of molybdenum trioxide in this invention are shown; where the arrows indicate the rotation direction of the substrate;

[0022] Figure 3 The excitation modes of hyperbolic resonators in three crystal directions on the MoO3 substrate of this invention are shown; where the straight line represents the asymptote of HVPP and the curve represents the dispersion curve of HVPP.

[0023] Figure 4 (a) is an angular frequency of 1.467 × 10⁻⁶. 14 rad / s, when the plate thickness t is 1200nm, the absolute value of the imaginary part of the reflection coefficient rpp changes in the wave vector space and (b) the spectral power changes with the angle; where R = 10nm, d = 600nm;

[0024] Figure 4 (b) shows the variation trend of spectral power Pφ under different substrate rotation angles φ;

[0025] Figure 5 The graph shows the variation of spectral power Pφ with angle at different particle spacings d when the plate thickness is 1200 nm.

[0026] Figure 6 The graphs show the variation of spectral power Pφ with angle for different plate thicknesses t; (a) interparticle spacing d = 600 nm, (b) interparticle spacing d = 900 nm.

[0027] The diagram is marked as follows:

[0028] 1. Substrate; 2. Nanoparticles; 3. Base plate; 4. Fixing plate; 5. Cantilever beam; 6. Knob. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0030] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0031] like Figure 1 As shown, a structure for regulating near-field radiative heat transfer based on hyperbolic materials includes a substrate 1 and nanoparticles 2, which are MoO3 particles, disposed on the substrate 1. The substrate 1 is made of MoO3. The hyperbolic radiative heat transfer peak (HVPP) excited by the substrate 1 provides anisotropic heat transfer channels for inter-particle radiative heat transfer. The radiative heat transfer between MoO3 particles is regulated by rotating the substrate 1. The substrate 1 is mounted on a base plate 3 via a linkage, and the MoO3 particles are suspended below a fixed plate 4 via a cantilever beam 5, with the fixed plate 4 positioned above the substrate 1. The overall size of this structure or device for regulating near-field radiative heat transfer based on hyperbolic materials is preferably on the order of 0.5*0.5*0.1 cm.

[0032] As an optional implementation, there are two MoO3 particles, with a spacing d between the two MoO3 particles of 300-1800 nm, and the radius of the MoO3 particles is 10 nm. The thickness of the substrate 1 is 100-1000 nm.

[0033] As an optional implementation, the substrate 1 is connected to the base plate 3 via a knob 6. The rotation of the base plate 3 drives the rotation of the substrate 1, thereby changing the radiative heat transfer. This knob can be an existing connection knob, which can drive the substrate to rotate synchronously when the base plate rotates.

[0034] The optical response of the anisotropic material MoO3 is related to the principal axis direction, and the components on the main diagonal of its relative permittivity matrix can be described by the Lorentz equation:

[0035]

[0036] Where ω is the angular frequency, LO is the longitudinal optics, TO is the transverse optics, j is the imaginary part of the complex number, and m = x, y, z are the crystal orientations of MoO3, corresponding to

[100] ,

[001] , and

[010] , as shown below. Figure 2 As shown.

[0037] like Figure 3 As shown, the excitation modes of hyperbolic excitons in the three crystal orientations of MoO3 are discussed. Figure 3 As shown in (a), when the substrate surface is perpendicular to the

[100] crystal direction of MoO3, its dielectric tensor is ε = diag(εy, εz, εx). At this time, the dielectric constant εx component perpendicular to the interface is positive, therefore there is no HSPP excitation. Since the dielectric constant εy and εz components in the plane have opposite signs, therefore... Figure 3 (a) We observed that HVPP can be excited on both sides of the origin. For example... Figure 3 As shown in (b), when the substrate surface is perpendicular to the

[001] crystal direction of MoO3, the dielectric constant tensor is ε = diag(εz, εx, εy). Since the out-of-plane dielectric constant is negative and both in-plane dielectric constant components are positive, there is no HSPP excitation, while HVPP can be excited at various angles within the plane. Figure 3 As shown in (c), when the substrate surface is perpendicular to the

[010] crystal direction of MoO3, the dielectric constant tensor is ε = diag(εx, εy, εz), and HVPP is excited on both sides above and below the origin, similar to the case in the

[100] crystal direction. In summary, Figure 3 Only HVPP was excited, not HSPP.

[0038] Next, we will discuss the radiative heat transfer characteristics when the crystal orientation is

[100] .

[0039] exist Figure 4 (a) shows the excitation of HVPP. Figure 4(b) illustrates the variation trend of spectral power Pφ under different substrate rotation angles φ. When the plate thickness is 1200 nm, the excitation of HVPP is discontinuous; this discreteness causes the spectral power to exhibit multiple peaks with varying rotation angles during plate rotation. From... Figure 4 (a) It can be seen that the dispersion curve at the large wave vector closely approximates the asymptote of the HVPP. In the figure, α is the angle between the y-axis and the HVPP asymptote, and β is the corresponding group velocity angle. Since the group velocity determines the velocity and direction of the energy flux, therefore... Figure 1 As shown, during the rotation of the plate in the xy plane, the radiative heat transfer between particles is maximized when the axis between particles is consistent with the group velocity corresponding to the HVPP excitation of the plate.

[0040] To clarify the near-field radiative heat transfer regulation mechanism of interparticle spacing, in Figure 5 The graph shows the variation of interparticle radiative heat transfer with substrate rotation angle under different particle spacings *d* when the plate thickness is 12 nm. When the particle spacing is small, it can be assumed that the particles directly radiate heat through the vacuum. In this case, the influence of the substrate on radiation is small, so the change in interparticle radiative heat transfer is small when the substrate is rotated. When the distance between particles is large, interparticle radiative heat transfer mainly occurs through the substrate, and the excitation of HVPP in the substrate enhances radiative heat transfer.

[0041] The effect of plate thickness t on radiative heat transfer is as follows: Figure 6 As shown. From Figure 6 The overall trend shows that the smaller the thickness of the plate, the greater the radiative heat transfer between NPs. From... Figure 6 As can be seen, when the plate thickness is small, the spectral power exhibits more peaks as the angle changes, a phenomenon related to the penetration depth. When the thickness is small, the in-plane wave vector is small, and the penetration depth is large. Compared with the case of a larger substrate thickness, in addition to HVPP excitation near the asymptote (corresponding to the peak at 0.29π), low-order HVPP excitation has a significant impact on radiative heat transfer.

[0042] This invention modulates interparticle radiative heat transfer by rotating the substrate, revealing that the excitation energy of HVPP in the substrate significantly enhances radiative heat transfer. Furthermore, by varying the particle spacing and substrate thickness, the modulating effect of HVPP excitation is further demonstrated: smaller particle spacing and thinner substrate thickness result in greater interparticle radiative heat transfer; larger particle spacing and thinner substrate thickness lead to more peaks in interparticle radiative heat transfer during substrate rotation. This invention can provide theoretical guidance for near-field radiative heat manipulation.

[0043] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in the details for the sake of brevity.

[0044] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A structure for regulating near-field radiative heat transfer based on hyperbolic metamaterials, comprising a substrate, characterized in that, The structure further comprises nanoparticles disposed above the substrate, the nanoparticles being MoO3 particles, the substrate being made of MoO3, and the substrate-excited hyperbolic phonon polaritons providing an anisotropic heat exchange channel for inter-particle radiative heat exchange, and the MoO3 particles being two, the distance d between the two MoO3 particles being 300-1800 nm, the radius of the MoO3 particles being 10 nm, and the excitation mode being controlled by rotating the substrate.

2. The structure for regulating near-field radiation heat transfer based on hyperbolic metamaterials according to claim 1, wherein, The substrate has a thickness of 100-1000 nm.

3. The structure for regulating near-field radiative heat transfer based on hyperbolic metamaterials of claim 1, wherein, The substrate is mounted on the bottom plate through a linkage, the MoO3 particles are hung below the fixed plate through cantilever beams, and the fixed plate is disposed above the substrate.

4. The structure for regulating near-field radiative heat transfer based on hyperbolic metamaterials according to claim 3, wherein, The linkage is a knob.

5. The structure for regulating near-field radiation heat transfer based on hyperbolic metamaterials of claim 1, wherein, The excitation mode includes excitation on the left and right sides of the origin, excitation on the upper and lower sides, and excitation at various angles in the plane.

6. The structure for regulating near-field radiation heat transfer based on hyperbolic metamaterials of claim 1, wherein, The control effect generated by the excitation of the hyperbolic phonon polaritons is exhibited by changing the particle spacing and the thickness of the substrate.

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