Thermal conductivity calculating device, thermal conductivity calculating method, and thermal conductivity calculating program

Abstract

The present invention addresses the problem of providing a thermal conductivity calculating device, a thermal conductivity calculating method, and a thermal conductivity calculating program that make it possible to measure the thermal conductivity of an amorphous material in a non-destructive, non-contact, non-heating manner, using terahertz light.　In order to solve the above problem, the present invention provides: a thermal conductivity calculating device comprising a terahertz light irradiating means for irradiating an amorphous material with terahertz light, a measuring means for measuring a complex permittivity spectrum from a response result relating to the irradiation of the amorphous material with terahertz light, and a calculating means for calculating the thermal conductivity of the amorphous material on the basis of the measurement result obtained by the measuring means; and a thermal conductivity calculating method and thermal conductivity calculating program related to the thermal conductivity calculating device.　According to the present invention, since the thermal conductivity can be calculated from the response result obtained by irradiating the amorphous material with terahertz light, the thermal conductivity of the amorphous material can be measured in a non-destructive, non-contact, non-heating manner.

Description

Thermal conductivity calculation device, thermal conductivity calculation method, and thermal conductivity calculation program

[0001] The present invention relates to a thermal conductivity calculation device, a thermal conductivity calculation method, and a thermal conductivity calculation program. More specifically, the present invention relates to a thermal conductivity calculation device, a thermal conductivity calculation method, and a thermal conductivity calculation program that calculate the thermal conductivity of amorphous materials using terahertz light.

[0002] Measurement of the physical properties of various materials is a means of obtaining information (physical property values) that is important for material evaluation and product improvement, and various measurement methods are used depending on the type of material and the physical property values ​​to be obtained.

[0003] One example of physical property measurement is the measurement of thermal conductivity, which is a physical property related to the ease with which heat is transmitted (thermal conduction) through a material. As shown in Non-Patent Document 1, thermal conductivity measurements are generally classified into steady-state methods and transient methods. Steady-state methods are methods in which a steady temperature gradient is applied to a sample (material) to measure thermal conductivity, and representative examples include the guarded hot plate method and the concentric cylinder absolute method. On the other hand, transient methods are methods in which thermal conductivity is calculated from the temperature response when a transient heat flow is applied to the sample (material), and representative examples include the pulse heating (laser flash) method, cyclic heating method, and hot wire method.

[0004] Furthermore, as a measuring device for measuring thermal conductivity, devices that enable measurement of thermal conductivity in a shorter time and with higher accuracy based on the above-mentioned steady-state method or unsteady-state method have been studied. For example, Patent Document 1 describes a thermal conductivity measuring device that includes first and second heat flux detecting means arranged opposite to each other so as to sandwich a measurement object at one end, a heat generating element, a heat absorbing element, and a heat flux control means, and that calculates thermal conductivity based on the heat flux (output) detected by the heat flux detecting means. Furthermore, Patent Document 2 describes a thermal conductivity measuring device that includes a heating means for transiently heating one end portion of the measurement sample, and a control means for calculating thermal conductivity based on temperature changes in the measurement portion extending from one end portion to the other end of the measurement sample, where three or more temperature measurement sections are provided in the measurement section, and the control means includes a temperature change detection means for detecting temperature changes in the temperature measurement sections, a representative area setting means for setting a representative measurement area in the temperature measurement sections using a difference in temperature change (first decay characteristic) or a derivative of this difference (second decay characteristic), a representative characteristic calculation means for calculating the decay time and temperature drop value from the peak time to the end of measurement, a heat capacity calculation means for calculating the heat capacity, and a thermal conductivity calculation means.

[0005] JP 2020-193934 A JP 2018-040653 A

[0006] Yukihiro Mitani, "Current Status of Thermal Conductivity Measurement," IIC REVIEW, April 2011, No. 45, pp. 42-49

[0007] Amorphous materials, such as glass, have many properties different from crystalline materials, such as metals and ceramics. Their thermal conductivity, a key thermal property, is particularly distinct from that of crystalline materials, exhibiting low thermal conductivity and characteristic temperature dependence. Amorphous materials with high thermal conductivity are preferred for use in electronic devices, while those used as insulating materials require low thermal conductivity. In particular, materials used in electronic devices are often small, making it necessary to accurately measure thermal conductivity in extremely small regions. However, conventional thermal conductivity measuring devices, such as those shown in Patent Documents 1 and 2, require heating, making it difficult to distinguish and measure thermal conductivity within extremely small regions. Furthermore, as the size of the material being measured becomes smaller, the heating process itself increases the likelihood of material denaturation (state change). Therefore, a technology for measuring thermal conductivity without causing material denaturation (state change) due to heating is needed.

[0008] In recent years, spectroscopy using electromagnetic waves in the terahertz band (0.1 THz to 100 THz) (hereinafter referred to as "terahertz light"), which has wavelengths intermediate between radio waves and light, has attracted attention. Terahertz light has the property of propagating in a straight line like light, while also exhibiting high transmittance through materials such as paper and plastic, like radio waves. Furthermore, frequencies in the terahertz band are equivalent to the frequencies of molecular rotation and vibration, crystal lattice vibration, and macromolecular vibration such as proteins. Therefore, spectroscopy using terahertz light has the potential to be applied to the identification and measurement of physical properties of various substances. Furthermore, terahertz spectroscopy is expected to be applicable in a wide range of industrial fields, including materials analysis, food, biotechnology, and medicine. Furthermore, terahertz spectroscopy, like spectroscopy using other wavelength ranges (visible, ultraviolet, infrared, near-infrared, etc.), allows for nondestructive and noncontact measurement of samples.

[0009] However, there are still fewer specific examples of spectroscopy using terahertz light compared to other spectroscopy methods. On the other hand, by using the response obtained by irradiating amorphous materials with terahertz light to enable the measurement of thermal properties, it is expected that physical property measurements will be possible not only non-destructively and non-contactly, but also without heating.

[0010] Therefore, an object of the present invention is to provide a thermal conductivity calculation device, a thermal conductivity calculation method, and a thermal conductivity calculation program that utilize terahertz light to enable non-destructive, non-contact, and non-heating measurement of the thermal conductivity of amorphous materials.

[0011] As a result of intensive research into the above-mentioned problems, the inventors have discovered that it is possible to measure the thermal conductivity of an amorphous material nondestructively, noncontactly, and without heating by irradiating the amorphous material with terahertz light, measuring predetermined parameters from the response results, and calculating the thermal conductivity based on the parameters obtained as a result of the measurement, and have completed the present invention. That is, the present invention is the following thermal conductivity calculation device, thermal conductivity calculation method, and thermal conductivity calculation program.

[0012] The thermal conductivity calculation device of the present invention, which solves the above-mentioned problems, is a thermal conductivity calculation device for calculating the thermal conductivity of an amorphous material, characterized by comprising: a terahertz light irradiation means for irradiating the amorphous material with terahertz light; a measurement means for measuring a complex dielectric constant spectrum from the response result of irradiating the amorphous material with terahertz light; and a calculation means for calculating the thermal conductivity of the amorphous material based on the measurement result obtained by the measurement means. The thermal conductivity calculation device of the present invention enables calculation of the thermal conductivity from the response result obtained by irradiating the amorphous material with terahertz light, thereby enabling nondestructive, noncontact, and rapid measurement of the thermal conductivity of amorphous materials. In particular, the fact that a complex dielectric constant spectrum is measured from the response result of irradiating the amorphous material with terahertz light and that the thermal conductivity can be calculated from this complex dielectric constant spectrum is based on new findings obtained through research by the present inventors. While Raman spectroscopy is known as a method for measuring the thermal conductivity of a material (sample) using spectroscopy, this method involves heating the sample with the excitation laser light used in Raman spectroscopy. On the other hand, the thermal conductivity calculation device of the present invention utilizes the response results of irradiating an amorphous material (sample) with terahertz light, and does not heat the sample. Therefore, the thermal conductivity calculation device of the present invention can measure thermal conductivity without heating, and also has the effect of accurately grasping the thermal conductivity of an amorphous material in a very small region.

[0013] In one embodiment of the thermal conductivity calculation device of the present invention, the calculation means includes a calculation means for calculating a complex elastic modulus spectrum using the complex dielectric constant spectrum and a calculation means for calculating thermal conductivity using the complex elastic modulus spectrum. According to this feature, when calculating thermal conductivity using the calculation means, it is possible to calculate (extract) the complex elastic modulus spectrum, which is a parameter involved in calculating various physical quantities, from the complex dielectric constant spectrum based on the relationship between the complex dielectric constant spectrum and the complex elastic modulus spectrum obtained as new findings through the inventors' research. Furthermore, by calculating thermal conductivity using this complex elastic modulus spectrum, various information related to the temperature dependence of thermal conductivity (such as the average value of the elastic modulus and the magnitude of fluctuation) can also be obtained. This has the effect of improving the calculation accuracy of thermal conductivity and enabling the acquisition of information related to physical properties other than thermal conductivity.

[0014] In addition, one embodiment of the thermal conductivity calculation device of the present invention is characterized in that the terahertz light irradiation means and the measurement means use spatially resolved terahertz spectroscopy. This feature makes it possible to individually determine the thermal conductivity of an amorphous material at each measurement point. In other words, it is possible to obtain more detailed information about the thermal conductivity of the amorphous material.

[0015] Furthermore, one embodiment of the thermal conductivity calculation device of the present invention is characterized by further comprising an information acquisition means for acquiring information related to the spatial distribution of thermal conductivity in an amorphous material. This feature enables the thermal conductivity at each measurement point of an amorphous material obtained by spatially resolved terahertz spectroscopy to be treated in the form of the spatial distribution of thermal conductivity in the amorphous material. This also makes it easier to accurately grasp the thermal conductivity of extremely small regions of the amorphous material. This is particularly effective in cases such as electronic devices, where precise understanding of the thermal conductivity of each material (including amorphous materials) used in a product is required to improve the product's functionality and quality.

[0016] Furthermore, one embodiment of the thermal conductivity calculation device of the present invention is characterized in that it further comprises a display means for displaying information related to the spatial distribution of thermal conductivity in the amorphous material obtained by the information acquisition means. This feature makes it easy to visually grasp the spatial distribution of thermal conductivity in the amorphous material. This makes it possible to effectively utilize thermal conductivity, which is information necessary for functional evaluation and improvement of amorphous materials.

[0017] The thermal conductivity calculation method of the present invention, which solves the above-mentioned problems, is a thermal conductivity calculation method for calculating the thermal conductivity of an amorphous material, and is characterized by comprising a terahertz light irradiation step of irradiating the amorphous material with terahertz light, a measurement step of measuring a complex dielectric constant spectrum from the response result of the terahertz light irradiation of the amorphous material, and a calculation step of calculating the thermal conductivity of the amorphous material based on the measurement result obtained in the measurement step. The thermal conductivity calculation method of the present invention enables calculation of the thermal conductivity from the response result obtained by irradiating the amorphous material with terahertz light, thereby enabling nondestructive, noncontact, and rapid measurement of the thermal conductivity of the amorphous material. Furthermore, as described above, the fact that a complex dielectric constant spectrum is measured from the response result of irradiating the amorphous material with terahertz light and that the thermal conductivity can be calculated from this complex dielectric constant spectrum is based on new findings obtained through research by the present inventors. The thermal conductivity calculation method of the present invention also has the effect of making it possible to measure thermal conductivity without heating, and accurately determining the thermal conductivity of an amorphous material in a very small region.

[0018] In addition, one embodiment of the thermal conductivity calculation method of the present invention is characterized in that the calculation step involves calculating the thermal conductivity after calculating a complex elastic modulus spectrum using the complex dielectric constant spectrum. According to this feature, when calculating the thermal conductivity in the calculation step, a complex elastic modulus spectrum, which is a parameter involved in calculating various physical quantities, is calculated (extracted) from the complex dielectric constant spectrum based on the relationship between the complex dielectric constant spectrum and the complex elastic modulus spectrum, which was newly discovered through the inventors' research. Using this complex elastic modulus spectrum, the thermal conductivity can be calculated, and various information related to the temperature dependence of the thermal conductivity (such as the average value of the elastic modulus and the magnitude of fluctuations) can also be obtained. This has the effect of improving the calculation accuracy of the thermal conductivity and enabling the acquisition of information related to physical properties other than the thermal conductivity.

[0019] In addition, one embodiment of the thermal conductivity calculation method of the present invention is characterized in that the terahertz light irradiation step and the measurement step are performed using spatially resolved terahertz spectroscopy. This feature makes it possible to individually determine the thermal conductivity of an amorphous material at each measurement point. In other words, it is possible to obtain more detailed information about the thermal conductivity of the amorphous material.

[0020] Furthermore, one embodiment of the thermal conductivity calculation method of the present invention is characterized by further comprising an information acquisition step of acquiring information related to the spatial distribution of thermal conductivity in an amorphous material. This feature enables the thermal conductivity at each measurement point of an amorphous material obtained by spatially resolved terahertz spectroscopy to be treated in the form of the spatial distribution of thermal conductivity in the amorphous material. This also makes it easier to accurately grasp the thermal conductivity of extremely small regions of the amorphous material. This method is particularly effective in cases such as electronic devices, where precise understanding of the thermal conductivity of each material (including amorphous materials) used in the product is required to improve the product's functionality and quality.

[0021] Furthermore, one embodiment of the thermal conductivity calculation method of the present invention is characterized by further comprising a display step of displaying information related to the spatial distribution of thermal conductivity in the amorphous material obtained in the information acquisition step. This feature makes it easy to visually grasp the spatial distribution of thermal conductivity in the amorphous material. This makes it possible to effectively utilize thermal conductivity, which is information necessary for functional evaluation and improvement of amorphous materials.

[0022] The thermal conductivity calculation program of the present invention, which aims to solve the above-mentioned problems, is a thermal conductivity calculation program for calculating the thermal conductivity of an amorphous material, and is characterized by executing the following steps: a terahertz light irradiation step of irradiating the amorphous material with terahertz light; a measurement step of measuring a complex dielectric constant spectrum from a response result related to the terahertz light irradiation of the amorphous material; and a calculation step of calculating the thermal conductivity of the amorphous material based on the measurement result obtained in the measurement step. The thermal conductivity calculation program of the present invention enables calculation of the thermal conductivity from the response result obtained by irradiating the amorphous material with terahertz light, thereby enabling nondestructive, noncontact, and rapid measurement of the thermal conductivity of the amorphous material. Furthermore, as described above, the fact that a complex dielectric constant spectrum is measured from the response result of irradiating the amorphous material with terahertz light and that the thermal conductivity can be calculated from this complex dielectric constant spectrum is based on new findings obtained through research by the present inventors.

[0023] According to the present invention, it is possible to provide a thermal conductivity calculation device, a thermal conductivity calculation method, and a thermal conductivity calculation program that utilize terahertz light to enable non-destructive, non-contact, and non-heating measurement of the thermal conductivity of amorphous materials.

[0024] Fig. 1 is a schematic explanatory diagram of a thermal conductivity calculation device according to a first embodiment of the present invention. Fig. 2 is a graph showing experimental values ​​and calculated values ​​of a complex dielectric constant spectrum obtained by the thermal conductivity calculation device according to the first embodiment of the present invention. Fig. 3 is a graph showing the calculation results of a complex elastic modulus spectrum (complex shear elastic modulus spectrum) obtained by the thermal conductivity calculation device according to the first embodiment of the present invention. Fig. 4 is a graph showing the calculation results (calculated values) of thermal conductivity obtained by the thermal conductivity calculation device according to the first embodiment of the present invention and the actual measured values ​​of thermal conductivity at that time. Fig. 5 is a schematic explanatory diagram of a thermal conductivity calculation device according to a second embodiment of the present invention.

[0025] The thermal conductivity calculation device, the thermal conductivity calculation method, and the thermal conductivity calculation program of the present invention are used to calculate the thermal conductivity of amorphous materials.

[0026] The amorphous material in the present invention refers to a material in a solid state (amorphous state or glass state) in which atoms (or molecules) are assembled without regular spatial arrangement, and specific examples include inorganic glass, organic glass, amorphous resin (amorphous polymer), rubber, polyhydric alcohols, etc. One of the characteristics of the amorphous material in the present invention is that an excitation (vibration mode) called a boson peak appears in the terahertz band. The boson peak is expressed as g(ν) / ν, where the frequency ν is the horizontal axis and the vibrational density of states g(ν) is divided by the square of the frequency ν. ２ , or α / ν, where α is the absorption coefficient divided by the square of the frequency ν ２ It refers to a peak that appears in a plot (spectrum) when the vertical axis is σ. Note that this boson peak is related to the characteristic physical properties of amorphous materials, such as low thermal conductivity, microscopic mechanical properties, and optical absorption in the terahertz band, and studies are being conducted to explain the behavior of the boson peak, as it is believed that information related to the physical properties of the above-mentioned amorphous materials can be obtained.

[0027] The thermal conductivity calculation device, thermal conductivity calculation method, and thermal conductivity calculation program of the present invention utilize terahertz light to calculate the thermal conductivity of amorphous materials. Terahertz light, also known as submillimeter waves or far-infrared rays, refers to electromagnetic waves in the terahertz band (0.1 THz to 100 THz), which have wavelengths intermediate between radio waves and light. Terahertz light propagates in a straight line like light, while also possessing high transmittance, like radio waves, allowing it to pass through materials such as paper and plastic.

[0028] The thermal conductivity calculation device, thermal conductivity calculation method, and thermal conductivity calculation program of the present invention irradiate an amorphous material sample with terahertz light and calculate the thermal conductivity from the resulting response. This enables nondestructive, noncontact, and rapid measurement of the thermal conductivity of amorphous materials. Furthermore, thermal conductivity measurement is possible without heating the sample.

[0029] Hereinafter, the embodiments of the thermal conductivity calculation device, the thermal conductivity calculation method, and the thermal conductivity calculation program of the present invention will be described in detail with reference to the drawings. The contents and drawings described in the embodiments are merely examples for easily explaining the features of the present invention, and the present invention is not limited thereto, and can be appropriately modified and implemented within the scope that does not change the gist of the present invention.

[0030] [First Embodiment] Figure 1 is a schematic diagram of a thermal conductivity calculation device according to a first embodiment of the present invention. As shown in Figure 1, the thermal conductivity calculation device 1A of this embodiment includes a terahertz light irradiation means 2 that irradiates terahertz light onto an amorphous material M as a sample, a measurement means 3 that measures a complex dielectric constant spectrum from the response results associated with the irradiation of the amorphous material M with terahertz light, and a calculation means 4 that calculates the thermal conductivity of the amorphous material M based on the measurement results obtained by the measurement means 3. In Figure 1, solid arrows indicate the optical path associated with the terahertz light irradiation, and dashed arrows indicate the output and input of various information (detection data and calculated parameters). Each component of the thermal conductivity calculation device 1A will be described below.

[0031] The terahertz light irradiation means 2 is used to perform a terahertz light irradiation step of irradiating terahertz light onto the amorphous material M. The terahertz light irradiation means 2 is not particularly limited as long as it has a configuration capable of irradiating terahertz light onto the amorphous material M. An example of the terahertz light irradiation means 2 in this embodiment is one that includes a terahertz light source and optical components (lenses, mirrors, etc.) for irradiating (focusing) the terahertz light onto the amorphous material M. Note that a known configuration can be used for the terahertz light source, and specifically, one that inputs light from a femtosecond laser into a terahertz emitter (photoconductive switching element) and converts it into terahertz light can be mentioned.

[0032] The measuring means 3 is used to perform a measurement step of measuring a complex dielectric constant spectrum from a response result associated with irradiation of the amorphous material M with terahertz light. The measuring means 3 may be configured to acquire information (data) associated with the response result associated with the terahertz light irradiated onto the amorphous material M by the terahertz light irradiating means 2, and further acquire information associated with the complex dielectric constant spectrum based on the acquired data, thereby measuring the complex dielectric constant spectrum. An example of the measuring means 3 of this embodiment includes a detecting means 31 and a data converting means 32, as shown in FIG. 1 .

[0033] The detection means 31 detects the response result of irradiating the amorphous material M with terahertz light. More specifically, it receives the terahertz light that has passed through the amorphous material M and detects its intensity. A known detector or detection element can be used as the detection means 31, such as a photoconductive antenna. The response result detected by the detection means 31 is the electric field intensity of the terahertz light that has passed through the amorphous material M. However, from the perspective of data handling (data conversion and calculation) in subsequent processes, it is preferable to perform a time sweep and convert the electric field intensity with respect to time, i.e., the time waveform of the electric field (hereinafter simply referred to as the "time waveform"). The detection means 31 may also include a lock-in amplifier to amplify the detected electric field intensity. The terahertz light irradiation means 2 and the detection means 31 may be configured as a known terahertz time-domain spectroscopy (THz-TDS).

[0034] The data conversion means 32 is for converting the response result detected by the detection means 31 into a complex dielectric constant spectrum, and more specifically, for converting the time waveform of the terahertz light transmitted through the amorphous material M, which is the result detected by the detection means 31, into a complex dielectric constant spectrum. The data conversion means 32 may be any means that can receive the response result detected by the detection means 31, ultimately convert it into a complex dielectric constant spectrum, and output it, and may include manual calculation by an operator. The data conversion means 32 in this embodiment may be a computing device that can execute, via a processor such as a CPU and a program, an arithmetic expression that converts the time waveform of the terahertz light into a complex dielectric constant spectrum through Fourier transform or the like, as input data.

[0035] Here, a known arithmetic expression can be used as the arithmetic expression in the data conversion means 32 (the expression for converting a time waveform into a complex dielectric constant spectrum). Specific examples of the data conversion means 32 include one that undergoes the following data conversion steps. First, amplitude information and phase information are obtained by Fourier transforming the time waveform. These two pieces of information can be used to obtain a complex refractive index, which is called an optical constant, and further, a complex dielectric constant. That is, a dielectric constant consisting of a real part and an imaginary part at each point (each time) corresponding to the time waveform is obtained, and it becomes possible to calculate the dielectric constant in the form of a complex dielectric constant spectrum. Note that the data conversion from the time waveform to the complex dielectric constant spectrum is not limited to the above-mentioned content, and can be performed based on other known arithmetic expressions or data conversion steps.

[0036] The calculation means 4 is for performing a calculation step of calculating the thermal conductivity of the amorphous material M based on the measurement results obtained by the measurement means 3. The calculation means 4 may be configured to be able to calculate the thermal conductivity of the amorphous material M from the complex dielectric constant spectrum obtained by the measurement means 3. The calculation means 4 in this embodiment may include manual calculation by an operator, but is preferably a calculation device that can execute an arithmetic formula for calculating the thermal conductivity via a processor such as a CPU and a program using the complex dielectric constant spectrum as input data.

[0037] In calculating thermal conductivity from a complex dielectric constant spectrum, no theoretical model relating to an appropriate arithmetic formula or calculation process has been constructed until now. Therefore, as a result of intensive studies by the present inventors, a new theoretical model relating to calculation (deriving) thermal conductivity from a complex dielectric constant spectrum has been constructed, and calculation is performed based on this theoretical model in the calculation means 4. Note that the calculation process in the calculation means 4 is not limited to being based on the theoretical model constructed by the present inventors, and other arithmetic formulas or other theoretical models capable of calculating thermal conductivity using a complex dielectric constant spectrum as input data may be used.

[0038] The theoretical model constructed by the present inventors as the theoretical model used in the calculation means 4 of this embodiment is, in brief, a theoretical model (relational formula) relating to the relationship between the complex dielectric constant spectrum and the complex elastic modulus spectrum, which is used to calculate (extract) the complex elastic modulus spectrum from the complex dielectric constant spectrum, and further to calculate the thermal conductivity from this complex elastic modulus spectrum. In particular, the theoretical model (relational formula) expressing the relationship between the complex dielectric constant spectrum and the complex elastic modulus spectrum is newly proposed by the present inventors.

[0039] Here, the complex modulus spectrum is one of the physical quantities that indicates the viscoelasticity of an object (the amorphous material in this embodiment), and is a spectrum that expresses the dynamic modulus, which is a concept that is an extension of the so-called Young's modulus, as a complex number. More specifically, the complex modulus spectrum is expressed as the sum of the storage modulus, which indicates shear elasticity, and the loss modulus, which indicates damping (viscoelastic) behavior, multiplied by the imaginary unit i.

[0040] The complex modulus spectrum can also be used to calculate various other physical quantities. In particular, the complex shear modulus spectrum, which indicates the hardness of an object against shear force (the object's resistance to shear deformation), can be used to determine the vibrational density of states, specific heat, dynamic structure factor, etc. Furthermore, it is also possible to determine thermal conductivity from the correlation between the vibrational density of states and the temperature dependence of thermal conductivity. Therefore, in this embodiment, the complex modulus spectrum particularly refers to the complex shear modulus spectrum.

[0041] The theoretical model used in the calculation means 4 of this embodiment will now be specifically described, including the calculation formula.

[0042] First, we will explain the theoretical model (relational equation) relating to the relationship between the complex permittivity spectrum and the complex elastic modulus spectrum. Here, the complex permittivity spectrum and the complex elastic modulus spectrum (complex shear modulus spectrum) are both parameters that depend on frequency (complex frequency). The complex frequency is expressed as the sum of a real number and an imaginary number (= ω + ie), but since e is a small positive real number, the complex frequency will be treated as the frequency value corresponding to the real part (frequency ω) hereinafter. Therefore, hereinafter, the complex permittivity spectrum will be represented as ε(ω) and the complex shear modulus spectrum as G(ω), and the relational equation relating to this theoretical model will be referred to as the ε(ω)-G(ω) equation.

[0043] This theoretical model starts from the equation of motion (wave equation) of a continuum in which adjacent atoms are connected, rather than a single oscillator, and considers the presence of charge fluctuations due to the structural inhomogeneity of amorphous materials. More specifically, in deriving the ε(ω)-G(ω) equation, we consider the fundamental equations of heterogeneous elasticity theory (HET), one of the models used to explain the behavior of boson peaks, taking into account charge fluctuations and the wave equation when an external electric field is applied.

[0044] As mentioned above, the boson peak generally corresponds to the g(ν) / ν obtained by dividing the vibrational density of states g(ν) by the square of the frequency ν when the frequency ν is plotted on the horizontal axis. ２ , or α / ν, where α is the absorption coefficient divided by the square of the frequency ν ２ The boson peak is a peak that appears in a plot (spectrum) when the vertical axis is σ, and the behavior of the boson peak has been analyzed and studied as it is believed to be related to the origin of the thermal properties unique to amorphous materials (their extremely low thermal conductivity compared to crystalline materials and their characteristic and universal temperature dependence). One of the representative models that explains the behavior of the boson peak is the HET.

[0045] HET is a theoretical model based on the assumption that the spring constant of lattice vibrations is different for each amorphous material due to its disordered structure. For example, in a typical elastic body, particles (atoms or molecules) of mass m are connected by springs, and the spring constant (k) of the lattice vibrations is considered to be constant. The equation of motion for the i-th mass m is given by Equation 1. Here, t is time, u is displacement, and x is position.

[0046] At this time, the wave equation showing how elastic waves propagate due to dynamic deformation of an elastic body is expressed as Equation 2. Here, K is the bulk modulus and ρ is the density of the system.

[0047] On the other hand, the equation of motion based on the HET is as shown in Equation 3.

[0048] Then, when the wave equation based on the HET is obtained from Equation 3, Equation 4 is obtained, which is called the fundamental equation of the HET. Note that K(x) in Equation 4 indicates that the bulk modulus is a variable that depends on the position x. When considering applying Equation 4, which is a one-dimensional model, to three dimensions, the physical quantity corresponding to K(x) becomes the above-mentioned complex shear modulus spectrum G(ω).

[0049] As described above, in deriving the ε(ω)-G(ω) equation, charge fluctuations are taken into account in the fundamental equation of HET shown in Equation 4, and a wave equation when an external electric field E(t) is applied is considered, and this wave equation is expressed as Equation 5. Here, Δq(x) is the charge density at the position x.

[0050] After Fourier transforming Equation 5, the polarizability α(ω) can be expressed by Equation 6 from the rearranged equation and the relationship between the displacement due to the external electric field and the polarizability. In addition, k Ｄ is the Debye wavenumber.

[0051] The relationship between polarizability and dielectric constant (complex dielectric constant spectrum ε(ω)) is given by Equation 7. In addition, ε∞ is the dielectric constant at ω → ∞, ε ０ is the dielectric constant of a vacuum.

[0052] By substituting Equation 6 into Equation 7, the relational equation (ε(ω)-G(ω) equation) between the complex permittivity spectrum and the complex shear modulus spectrum is derived as shown in Equation 8.

[0053] On the other hand, as described above, the complex shear modulus spectrum G(ω) is one of the parameters for calculating the vibrational density of states. More specifically, it is known that the vibrational density of states g(ω) can be expressed by the following equation 9 using the complex shear modulus spectrum G(ω): In addition, G Ｌ (k, ω) and G Ｔ (k, ω) are Green functions, which represent the vertical and horizontal Green functions, respectively. ｅｘｐ is the macroscopic bulk modulus, which is obtained experimentally.

[0054] As shown in Equation 9, it can be seen that the vibrational density of states g(ω) can be analytically calculated using the complex shear modulus spectrum G(ω). Furthermore, according to the theory proposed by W. Schirmacher, it is known that there is a correlation between the vibrational density of states g(ω) and the temperature dependence of thermal conductivity κ(T), which can be more specifically expressed by the following Equation 10.

[0055] Therefore, as can be seen from Equations 9 and 10, if the complex shear modulus spectrum G(ω) of an amorphous material can be obtained, it becomes possible to calculate the thermal conductivity κ (temperature dependence of thermal conductivity κ(T)) of the amorphous material. In other words, calculation of the complex shear modulus spectrum G(ω) is important for calculating the thermal conductivity κ of an amorphous material.

[0056] This theoretical model calculates (extracts) the complex shear modulus spectrum G(ω) from the complex permittivity spectrum ε(ω). Here, in this theoretical model, "calculating (extracting) the complex shear modulus spectrum G(ω) from the complex permittivity spectrum ε(ω)" refers to using the value of the complex permittivity spectrum obtained by the measuring means 3 in the process of calculating the complex modulus spectrum (complex shear modulus spectrum), and there is no particular limitation on how the value of the complex permittivity spectrum is used. A specific example of calculating (extracting) the complex shear modulus spectrum G(ω) from the complex permittivity spectrum ε(ω) in this theoretical model will be described below.

[0057] As a specific example, the complex shear modulus spectrum G(ω) for each frequency is calculated from the value of the complex permittivity spectrum ε(ω) obtained by the measuring means 3 and the ε(ω)-G(ω) formula shown in Formula 8. This can simplify the calculation process by using only ω and G(ω) on the right side of Formula 8 as variables and setting the other values ​​as constants (or regarding them as constants).

[0058] Another specific example is a method of calculating the complex shear modulus spectrum G(ω) by solving the coherent potential approximation (hereinafter referred to as CPA) equation, which is one of the methods for analyzing the behavior of boson peaks. One example of this CPA equation is the self-consistent CPA equation proposed by Z. Pan et al. In this case, the complex shear modulus spectrum G(ω) is calculated by solving two parameters in the CPA equation that are involved in the elastic modulus fluctuations (the variance σ of the probability density function of the elastic modulus) ２ and the lowest possible coarse-grained wavenumber k ｅ The complex shear modulus spectrum G(ω) obtained as a solution to the CPA equation is input into the ε(ω)-G(ω) equation shown in Equation 8, and the complex permittivity spectrum ε(ω) obtained is determined by the variance σ of the probability density function of the modulus so that the value of the complex permittivity spectrum ε(ω) matches the value of the complex permittivity spectrum ε(ω) obtained by the measuring means 3. ２ and the lowest possible coarse-grained wavenumber k ｅThis involves changing the value of (performing fitting).

[0059] It should be noted that the specific example relating to the calculation (extraction) of the complex shear modulus spectrum G(ω) from the complex permittivity spectrum ε(ω) shown here is merely an example, and the present invention is not limited to this. However, in any case, it is preferable to use the ε(ω)-G(ω) formula shown in Equation 8 in addition to the value of the complex permittivity spectrum ε(ω) obtained by the measuring means 3. Furthermore, the ε(ω)-G(ω) formula shown in Equation 8 may also be expanded by adding, subtracting, multiplying, or dividing a coefficient or a constant.

[0060] Then, as described above, the vibrational density of states g(ω) is calculated from the obtained complex shear modulus spectrum G(ω) based on Equation 9, and then the thermal conductivity κ (temperature dependence of thermal conductivity κ(T)) is calculated based on Equation 10 and output from the calculation means 4 to the outside.

[0061] The calculation of the thermal conductivity of an amorphous material by the thermal conductivity calculation device 1A of this embodiment will be described below based on an example. Note that the operations and actions of the respective means in this example correspond to the respective steps of the thermal conductivity calculation method of this embodiment.

[0062] Using glycerol glass as the amorphous material M, measurements were carried out at a temperature of 80K using THz-TDS (corresponding to the terahertz light irradiation means 2 and measurement means 3 (detection means 31) in this embodiment).

[0063] FIG. 2 is a graph of the complex permittivity spectrum (real and imaginary parts) versus frequency. The horizontal axis of FIG. 2 represents frequency ω, the vertical axis (left side) represents the real part of the permittivity (ε′), and the vertical axis (right side) represents the imaginary part of the permittivity (ε″).

[0064] The solid line in FIG. 2 is a complex permittivity spectrum (experimental value) obtained by converting the time waveform obtained by measurement using the THz-TDS into the form of a complex permittivity spectrum by the data conversion means 32. The upper solid line in FIG. 2 indicates the real part (ε') of the permittivity, and the lower solid line indicates the imaginary part (ε") of the permittivity. On the other hand, the dashed line in FIG. 2 is a complex permittivity spectrum (calculated value) calculated by the calculation means 4 using the above-mentioned ε(ω)-G(ω) equation (Equation 8). The upper dashed line in FIG. 2 indicates the real part (ε') of the permittivity, and the lower dashed line indicates the imaginary part (ε") of the permittivity. The dashed line in FIG. 2 is a complex shear modulus spectrum G(ω) obtained as a solution to the self-consistent CPA equation, inputted into the ε(ω)-G(ω) equation (Equation 8), and the variance σ of the probability density function of the modulus is calculated so that the value of the complex permittivity spectrum obtained as a result (calculated value) coincides with the experimental value. ２ and the lowest possible coarse-grained wavenumber k ｅ The value of is changed (fitting is performed).

[0065] As shown in FIG. 2 , the complex permittivity spectrum (dashed line), calculated using the ε(ω)-G(ω) equation (Equation 8), closely reproduces the experimental complex permittivity spectrum (solid line), particularly in the frequency range of 1.5 THz or less. In other words, by using the ε(ω)-G(ω) equation (Equation 8) newly constructed by the inventors, it is possible to calculate (extract) the complex shear modulus spectrum G(ω) from the complex permittivity spectrum ε(ω) obtained as a response result when the amorphous material M is irradiated with light by the terahertz light irradiation means 2. Note that in FIG. 2 , the difference between the experimental value and the calculated value is large at frequencies above 1.5 THz. This is due to the fact that the CPA equation used to calculate the calculated value is not applicable. Therefore, it is possible to improve this reproducibility by improving the accuracy of the calculation using the CPA equation and expanding its range of application.

[0066] Then, the calculation means 4 calculates the thermal conductivity κ using the complex shear modulus spectrum G(ω) at this time, and outputs the result to the outside.

[0067] Fig. 3 shows the calculation results of the complex shear modulus spectrum G(ω) calculated (extracted) from the complex permittivity spectrum ε(ω), as an example of calculation by the calculation means 4. More specifically, Fig. 3 shows the calculation results of the complex shear modulus spectrum G(ω) extracted from the calculated value (broken line) of the complex permittivity spectrum in Fig. 2. The horizontal axis in Fig. 3 relates to frequency, and the frequency ω is expressed as the Debye frequency ω. Ｄ The vertical axis of FIG. 3 relates to the complex shear modulus spectrum, and the vertical axis at the top of FIG. 3 represents the real part of the complex shear modulus spectrum (Re[G(ω) / G ０ ]), the vertical axis at the bottom of Figure 3 is the imaginary part of the complex shear modulus spectrum (Im[G(ω) / G ０ ]) where G ０ indicates the geometric mean of the shear modulus and is used to make the vertical axis of Figure 3 dimensionless.

[0068] Furthermore, Fig. 4 shows, as an example of calculation by the calculation means 4, the calculation results (calculated values) of the thermal conductivity (temperature dependence κ(T) of thermal conductivity) based on Equations 9 and 10 using the calculation results of the complex shear modulus spectrum G(ω) shown in Fig. 3, and the actual measured values ​​of the thermal conductivity of the amorphous material M at that time measured by a conventional method. Note that the horizontal and vertical axes of Fig. 4 use non-dimensional values. More specifically, the horizontal axis of Fig. 4 relates to temperature, and the temperature T is expressed as the Debye temperature θ Ｄ The vertical axis of FIG. 4 relates to the thermal conductivity, and the temperature dependence of the thermal conductivity κ (T) is shown as the reference thermal conductivity κ ｒｅｆ The values ​​are shown divided by .

[0069] As shown in FIG. 4, the temperature dependence κ(T) of the thermal conductivity of the amorphous material M was calculated from the complex shear modulus spectrum G(ω) using the calculation means 4 in this embodiment (the broken line in FIG. 4, corresponding to the example) and the actual measurement value (the circle in FIG. 4) were well reproduced.

[0070] As described above, the thermal conductivity calculation device 1A in this embodiment irradiates the amorphous material M with terahertz light using the terahertz light irradiation means 2, measures a complex dielectric constant spectrum from the response result at this time using the measurement means 3, and further calculates the thermal conductivity of the amorphous material M from the complex dielectric constant spectrum using the calculation means 4, thereby enabling the thermal conductivity of the amorphous material to be calculated non-destructively, non-contactly, and without heating.

[0071] The thermal conductivity calculation method in this embodiment performs operations related to the respective means of the thermal conductivity calculation device 1A, and includes an operation by the terahertz light irradiation means 2 (terahertz light irradiation step), an operation by the measurement means 3 (measurement step), and an operation by the calculation means 4 (calculation step). This makes it possible to calculate the thermal conductivity of the amorphous material M non-destructively, non-contactly, and without heating.

[0072] Furthermore, the thermal conductivity calculation program in this embodiment is for executing the functions of each means (and each step in the thermal conductivity calculation method) of the thermal conductivity calculation device 1A described above, and is preferably created to execute each function via a processor such as a CPU, etc. This enables automation of thermal conductivity calculation and facilitates rapid calculation.

[0073] More specifically, the thermal conductivity calculation device 1A of this embodiment, and the thermal conductivity calculation method and thermal conductivity calculation program associated with the thermal conductivity calculation device 1A, enable calculation of thermal conductivity from the response results obtained by irradiating an amorphous material with terahertz light, thereby enabling non-destructive, non-contact, and rapid measurement of the thermal conductivity of amorphous materials. In particular, by using the relationship between the complex dielectric constant spectrum and the complex elastic modulus spectrum (complex shear modulus spectrum) (ε(ω)-G(ω) equation), which is a newly discovered finding through the inventors' research, it becomes possible to calculate the thermal conductivity of amorphous materials from the complex dielectric constant spectrum, which has previously been difficult to calculate (for which no appropriate theoretical model existed). Furthermore, the thermal conductivity calculation device 1A, thermal conductivity calculation method, and thermal conductivity calculation program of this embodiment utilize the response results from irradiating an amorphous material with terahertz light, and do not result in sample heating. Therefore, the thermal conductivity calculation device 1A, thermal conductivity calculation method, and thermal conductivity calculation program of this embodiment enable thermal conductivity measurement without heating. In other words, it is possible to distinguish and grasp the thermal conductivity within a very small region of the amorphous material.

[0074] [Second embodiment] Figure 5 is a schematic diagram (plan view) showing a thermal conductivity calculation device in a second embodiment of the present invention. As shown in Figure 5, the thermal conductivity calculation device 1B in this embodiment is the same as the thermal conductivity calculation device 1A in the first embodiment, except that it further includes an information acquisition means 5 for acquiring information related to the spatial distribution of thermal conductivity in the amorphous material M, and a display means 6 for displaying the information related to the spatial distribution of thermal conductivity in the amorphous material M obtained by the information acquisition means 5. In addition, in the thermal conductivity calculation device 1B in this embodiment, the terahertz light irradiation means 2 and the measurement means 3 are based on spatially resolved terahertz spectroscopy. Note that descriptions of components that are the same as those in the first embodiment will be omitted.

[0075] The thermal conductivity calculation device 1B in this embodiment is similar to the thermal conductivity calculation device 1A in the first embodiment in that it uses the response result (complex dielectric constant spectrum) resulting from irradiation of terahertz light to the amorphous material M to calculate the thermal conductivity using the calculation means 4. The thermal conductivity calculation device 1B in this embodiment is constructed (designed and configured) so that the terahertz light irradiation means 2 and the measurement means 3 (particularly the detection means 31) are capable of spatially resolved terahertz spectroscopy, and acquires information relating to the spatial distribution of the thermal conductivity of the amorphous material M using the information acquisition means 5. Furthermore, the information acquired by the information acquisition means 5 is displayed using the display means 6.

[0076] The terahertz light irradiation means 2 and the measurement means 3 (particularly the detection means 31) in this embodiment may be constructed (designed and configured) to perform spatially resolved terahertz spectroscopy, and their specific structure and configuration are not particularly limited. For example, a configuration known as terahertz spectroscopic imaging (terahertz imaging) can be used. More specifically, examples include two-dimensional scanning of a sample (the amorphous material M in this embodiment) to detect the response to terahertz light irradiation at each measurement point (a raster scan method), and a real-time measurement method (an EO sampling method) in which terahertz light transmitted through an EO crystal (an electro-optic crystal) and a probe light are incident coaxially and the polarization change of the probe light is detected with a CCD camera. Furthermore, the spatial resolution is not particularly limited. Examples include so-called two-dimensional imaging, which measures the XY plane of the sample, and three-dimensional imaging, which measures the XYZ space including the thickness direction (Z direction) of the sample. As a result, the detecting means 31 detects the time waveform at each measurement point in the amorphous material M, and the data converting means 32 converts it into the form of a complex dielectric constant spectrum at each measurement point.

[0077] In the thermal conductivity calculation device 1B of this embodiment, the complex dielectric constant spectrum output from the measurement means 3 (data conversion means 32) is input to the calculation means 4, and the complex elastic modulus spectrum is calculated (extracted) from the complex dielectric constant spectrum, similarly to the first embodiment described above, to calculate the thermal conductivity at each measurement point. That is, in the thermal conductivity calculation device 1B of this embodiment, it is possible to obtain more detailed information regarding the thermal conductivity of the amorphous material M.

[0078] The thermal conductivity at each measurement point obtained by the calculation means 4 is input into the information acquisition means 5, and information related to the spatial distribution of thermal conductivity in the amorphous material M is acquired. The information acquisition means 5 in this embodiment may include manual calculation by an operator, as with the calculation means 4, but is preferably a calculation device that can execute numerical processing via a processor such as a CPU and a program, using the thermal conductivity at each measurement point as input data and outputting information related to the spatial distribution of thermal conductivity. The calculation means 4 and the information acquisition means 5 may be provided separately, or the functions of the information acquisition means 5 may be integrated with the calculation means 4.

[0079] By providing the information acquisition means 5, it becomes possible to treat the thermal conductivity at each measurement point of the amorphous material M obtained by spatially resolved terahertz spectroscopy in the form of a spatial distribution of the thermal conductivity of the amorphous material M. This also makes it easy to accurately grasp the thermal conductivity in a very small region of the amorphous material M. This is particularly effective in cases such as electronic devices where it is necessary to precisely grasp the thermal conductivity of each material (including amorphous materials) used in the product in order to improve the product's functionality and quality.

[0080] Furthermore, information relating to the spatial distribution of thermal conductivity in the amorphous material M obtained by the information acquisition means 5 is input to the display means 6, and this information is displayed externally. The display means 6 in this embodiment may be any device capable of externally displaying information relating to the spatial distribution of thermal conductivity in the amorphous material M, and may, for example, be equipped with a display or monitor that can display information in a form that can be visually recognized by an operator. The display means 6 may also be equipped with a function that allows the display content to be changed, and may be provided with an instruction means for instructing the selection, enlargement, reduction, etc. of the display content, and the display content may be changed based on the instructions of the instruction means. Specific examples of the instruction means include input devices such as a keyboard or mouse, as well as input via a touch panel.

[0081] By providing the display means 6, it becomes easy to visually grasp the spatial distribution of the thermal conductivity in the amorphous material M. This makes it possible to effectively utilize the thermal conductivity, which is information necessary for functional evaluation and improvement of the amorphous material M.

[0082] As described above, in the thermal conductivity calculation device 1B of this embodiment, the terahertz light irradiating means 2 and the measuring means 3 are based on spatially resolved terahertz spectroscopy, the terahertz light irradiating means 2 irradiates the amorphous material M with terahertz light, the measuring means 3 measures a complex dielectric constant spectrum at each measurement point from the response result at this time, and the calculation means 4 calculates the thermal conductivity of the amorphous material M at each measurement point from the complex dielectric constant spectrum. Furthermore, the thermal conductivity calculation device 1B of this embodiment acquires information related to the spatial distribution of the thermal conductivity of the amorphous material M by the information acquiring means 5 based on the thermal conductivity output from the calculating means 4, and displays the information externally by the display means 6. This makes it possible to acquire and display information related to the spatial distribution of the thermal conductivity in addition to calculating the thermal conductivity.

[0083] The thermal conductivity calculation method in this embodiment performs operations related to each means of the thermal conductivity calculation device 1B, including an operation by the terahertz light irradiation means 2 (terahertz light irradiation step), an operation by the measurement means 3 (measurement step), an operation by the calculation means 4 (calculation step), an operation by the information acquisition means 5 (information acquisition step), and an operation by the display means 6 (display step), and in addition to calculating the thermal conductivity of the amorphous material M, acquires information related to the spatial distribution of the thermal conductivity of the amorphous material M and externally displays that information. This makes it possible to acquire and display information related to the spatial distribution of the thermal conductivity in addition to calculating the thermal conductivity.

[0084] Furthermore, it is preferable to create a thermal conductivity calculation program in this embodiment that executes the functions of each means (and each step in the thermal conductivity calculation method) of the thermal conductivity calculation device 1B via a processor such as a CPU, thereby enabling automation of the thermal conductivity calculation, facilitating not only rapid thermal conductivity calculation but also rapid acquisition and display of information related to the spatial distribution of thermal conductivity.

[0085] More specifically, the thermal conductivity calculation device 1B and the thermal conductivity calculation method and thermal conductivity calculation program using the thermal conductivity calculation device 1B of this embodiment perform spatially resolved terahertz spectroscopy, taking advantage of the fact that sample heating does not occur during thermal conductivity calculation, thereby enabling the acquisition and external display of information related to the spatial distribution of amorphous materials. In other words, the tendency (distribution) of thermal conductivity within a very small region of an amorphous material can be easily grasped, and this effect can be utilized to improve and refine the quality of the amorphous material itself and the product.

[0086] The above-described embodiments are examples of the thermal conductivity calculation device, the thermal conductivity calculation method, and the thermal conductivity calculation program according to the present invention. The thermal conductivity calculation device, the thermal conductivity calculation method, and the thermal conductivity calculation program according to the above-described embodiments may be modified within the scope of the claims.

[0087] The thermal conductivity calculation device, thermal conductivity calculation method, and thermal conductivity calculation program of the present invention can be used to calculate the thermal conductivity of amorphous materials. Furthermore, because the thermal conductivity calculation device, thermal conductivity calculation method, and thermal conductivity calculation program of the present invention can calculate the thermal conductivity of amorphous materials without heating, they can be particularly useful in cases where detailed information on the thermal properties (thermal conductivity) of amorphous materials in extremely small regions is required to improve the functionality and quality of products, such as amorphous materials used in electronic devices.

[0088] 1A, 1B Thermal conductivity calculation device, 2 Terahertz light irradiation means, 3 Measurement means, 31 Detection means, 32 Data conversion means, 4 Calculation means, 5 Information acquisition means, 6 Display means, M Amorphous material

Claims

1. A thermal conductivity calculation device for calculating the thermal conductivity of an amorphous material, comprising: a terahertz light irradiation means for irradiating the amorphous material with terahertz light; a measurement means for measuring a complex dielectric constant spectrum from a response result related to the irradiation of the amorphous material with terahertz light; and a calculation means for calculating the thermal conductivity of the amorphous material based on the measurement result obtained by the measurement means.

2. The thermal conductivity calculation device according to claim 1, characterized in that the calculation means includes calculation of a complex elastic modulus spectrum using the complex dielectric constant spectrum, and calculation of thermal conductivity using the complex elastic modulus spectrum.

3. The thermal conductivity calculation device according to claim 1, wherein the terahertz light irradiation means and the measurement means are based on spatially resolved terahertz spectroscopy.

4. The thermal conductivity calculation device according to claim 3, further comprising information acquisition means for acquiring information relating to the spatial distribution of thermal conductivity in the amorphous material.

5. The thermal conductivity calculation device according to claim 4, further comprising display means for displaying information relating to the spatial distribution of thermal conductivity in said amorphous material obtained by said information acquisition means.

6. A thermal conductivity calculation method for calculating the thermal conductivity of an amorphous material, comprising: a terahertz light irradiation step of irradiating the amorphous material with terahertz light; a measurement step of measuring a complex dielectric constant spectrum from a response result related to the irradiation of the amorphous material with terahertz light; and a calculation step of calculating the thermal conductivity of the amorphous material based on the measurement result obtained in the measurement step.

7. A thermal conductivity calculation method according to claim 6, characterized in that the calculation step involves calculating a complex elastic modulus spectrum using the complex dielectric constant spectrum, and then calculating the thermal conductivity.

8. The thermal conductivity calculation method according to claim 6, wherein the light irradiation step and the measurement step are performed by spatially resolved terahertz spectroscopy.

9. The thermal conductivity calculation method according to claim 8, further comprising an information acquisition step of acquiring information relating to the spatial distribution of thermal conductivity in the amorphous material.

10. The thermal conductivity calculation method according to claim 9, further comprising a display step of displaying information relating to the spatial distribution of thermal conductivity in the amorphous material obtained in the information acquisition step.

11. A thermal conductivity calculation program for calculating the thermal conductivity of an amorphous material, the program executing the following steps: a terahertz light irradiation step of irradiating the amorphous material with terahertz light; a measurement step of measuring a complex dielectric constant spectrum from a response result related to the irradiation of the amorphous material with terahertz light; and a calculation step of calculating the thermal conductivity of the amorphous material based on the measurement result obtained in the measurement step.

Images