KR20210078689A - PbTe-AgSbTe2 compounds and manufacturing method of the same - Google Patents

Abstract

The present invention relates to a PbTe-AgSbTe_2 based compound having a structure in which PbTe forms a matrix and AgSbTe_2 nanostructures are dispersed in the PbTe matrix, and to a method for preparing the compound. According to the present invention, the AgSbTe_2 nanostructures are dispersed in the PbTe matrix, and have thermal conductivity lower than 1.33 W/mK.

Description

PbTe-AgSbTe2 compounds and manufacturing method thereof {PbTe-AgSbTe2 compounds and manufacturing method of the same}

The present invention relates to a PbTe-AgSbTe ₂ based compound and a method for preparing the same, and more particularly, _{PbTe having AgSbTe 2} nanostructures dispersed in a PbTe matrix and having a thermal conductivity lower than 1.33 W/mK. -AgSbTe relates to a _2- based compound and a method for preparing the same.

The medium temperature thermoelectric element is expected to be applicable to power generation using waste heat in the aerospace field as well as in the recovery and power generation of automobile waste heat that is discarded without being regenerated in the industrial field. Recently, it is predicted that the market will expand to the field of bio and wireless center network (WSN). In addition, it is predicted that the development potential of other industrial thermoelectric devices is very high.

Of the energy used in the steelmaking process of the steel mill, 48.7% is actually used in the steelmaking process, and 7.8% of the waste heat is recycled into hot water and supplied to district heating, while the remaining 43.5% of the energy is being discharged as waste heat.

On the other hand, a chalcogen compound is a material made of a combination of a chalcogen element (Se, Te, etc.) and a transition metal, etc., is called a chalcogen compound, and a representative material is a material such as PbTe, Sb ₂ Te ₃ , AgSbTe ₂ there is

Republic of Korea Patent Publication No. 10-1531011

The problem to be solved by the present invention is _{to provide a PbTe-AgSbTe 2 based compound having a structure in which AgSbTe 2} nanostructures are dispersed in a PbTe matrix and having a thermal conductivity lower than 1.33 W/mK and a method for preparing the same .

The present invention provides _{a PbTe-AgSbTe 2} based compound in _{which PbTe forms a matrix and AgSbTe 2} nanostructures are dispersed in a PbTe matrix.

In the PbTe-AgSbTe _2- based compound, Ag, Pb, Sb, and Te constituting a chemical composition may be in a molar ratio of 1 to 5:18:11 to 5:20.

The PbTe-AgSbTe _2- based compound may exhibit a relative density higher than 99%.

The PbTe-AgSbTe _2- based compound may exhibit a thermal conductivity lower than 1.33 W/mK.

In addition, the present invention, (a) mixing Ag, Pb, Sb and Te, (b) putting a mixture of Ag, Pb, Sb and Te in a container, exhausting the interior of the container to achieve a vacuum state, , purging while injecting an inert gas into the vessel, (c) filling and sealing the inside of the vessel with an inert gas, and (d) melting a mixture of Ag, Pb, Sb and Te contained in the vessel. It provides a method for producing _{a PbTe-AgSbTe two-} based compound, comprising the steps of: (e) rapidly cooling the molten product, and (f) heat-treating the quenched product.

It is preferable to mix Ag, Pb, Sb and Te in a molar ratio of 1-5:18:1-5:20.

The melting is preferably performed at a temperature of 960 to 1150 °C.

In step (d), the melting may be performed while the vessel is charged in a rocking furnace and the vessel is rocked.

The heat treatment is preferably performed at a temperature of 200 to 750 ℃.

A quartz tube may be used as the container.

In step (b), it is preferable to exhaust ^{the inside of the container to achieve a vacuum of 10 -4} to 10 ^{-1 torr.}

The PbTe-AgSbTe ₂ compound has a structure in which PbTe forms a matrix, and AgSbTe ₂ nanostructures are dispersed in a PbTe matrix.

The PbTe-AgSbTe _2- based compound may exhibit a relative density higher than 99%.

The PbTe-AgSbTe _2- based compound may exhibit a thermal conductivity lower than 1.33 W/mK.

According to the present invention, AgSbTe ₂ nanostructures are dispersed in a PbTe matrix and have thermal conductivity lower than 1.33 W/mK. The _{PbTe-AgSbTe 2 compound, in which AgSbTe 2} nanostructures are well dispersed in the PbTe matrix, shows thermal conductivity lower than 1.33 W/mK, and thermal conductivity can be controlled depending on the crystal distribution and size of _{AgSbTe 2 nanostructures (nanostructures).} can

AgSbTe ₂ nanostructures (nanostructures) form interfaces while having coherent geometries with the PbTe matrix. This interface is more effective to act as phonon scattering sources and significantly lowers the overall thermal conductivity.

1 is a diagram showing an X-ray diffraction (XRD; X-ray diffraction) pattern of a _{PbTe-AgSbTe 2-} based compound prepared according to Experimental Example 1. FIG.
2 is a view showing X-ray diffraction (XRD; X-ray diffraction) patterns of _{PbTe-AgSbTe 2-} based compounds prepared according to Experimental Examples 2 to 6;
_{3a is a transmission electron microscope (TEM) photograph showing the PbTe-AgSbTe 2-} based compound prepared according to Experimental Example 6, and FIG. 3b is a transmission electron microscope (TEM) photograph showing the _{PbTe-AgSbTe 2-based compound prepared according to Experimental Example 5} It is an electron microscope (TEM) photograph, and FIG. 3c is a transmission electron microscope (TEM) photograph showing _{the PbTe-AgSbTe 2-based compound prepared according to Experimental Example 3.}
4 is a view showing the results of analyzing the size distribution of a nanostructure based on a transmission electron microscope.
Figure 5a is a graph showing the total thermal conductivity (total thermal conductivity) according to the temperature of the _{PbTe-AgSbTe 2-} based compound prepared according to Experimental Example 1, Experimental Example 2, Experimental Example 3, Experimental Example 5, and Experimental Example 6; 5b is a graph showing the lattice thermal conductivity _{of the PbTe-AgSbTe 2-} based compounds prepared according to Experimental Example 1, Experimental Example 2, Experimental Example 3, Experimental Example 5, and Experimental Example 6.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. However, the following examples are provided so that those of ordinary skill in the art can fully understand the present invention, and may be modified in various other forms, and the scope of the present invention is limited to the examples described below it's not going to be

When it is said that any one component "includes" another component in the detailed description or claims of the invention, it is not construed as being limited to only the component, unless otherwise stated, and other components are further added. It should be understood as being able to include

Hereinafter, the term “nano” refers to a size of 1 nm or more and smaller than 1 μm, and “nanostructure” is used to mean a nano-sized structure of 1 nm or more and smaller than 1 μm.

_{The PbTe-AgSbTe 2} based compound according to a preferred embodiment of the present invention has a structure in which PbTe forms a matrix and AgSbTe ₂ nanostructures are dispersed in a PbTe matrix.

In the PbTe-AgSbTe _2- based compound, Ag, Pb, Sb, and Te constituting a chemical composition may be in a molar ratio of 1 to 5:18:1 to 5:20.

The PbTe-AgSbTe _2- based compound may exhibit a relative density higher than 99%.

The PbTe-AgSbTe _2- based compound may exhibit a thermal conductivity lower than 1.33 W/mK.

_{A method for producing a PbTe-AgSbTe two-} based compound according to a preferred embodiment of the present invention comprises the steps of (a) mixing Ag, Pb, Sb and Te, and (b) a mixture of Ag, Pb, Sb and Te in a container. and purging while injecting and evacuating the inside of the container to achieve a vacuum state, and injecting an inert gas into the container, (c) filling and sealing the inside of the container with an inert gas, (d) in the container It includes the steps of melting a mixture of Ag, Pb, Sb and Te contained therein, (e) allowing the molten product to be rapidly cooled, and (f) heat-treating the quenched product.

It is preferable to mix Ag, Pb, Sb and Te in a molar ratio of 1-5:18:1-5:20.

The melting is preferably performed at a temperature of 960 to 1150 °C.

In step (d), the melting may be performed while the vessel is charged in a rocking furnace and the vessel is rocked.

The heat treatment is preferably performed at a temperature of 200 to 750 °C.

A quartz tube may be used as the container.

In step (b), it is preferable to exhaust ^{the inside of the container to achieve a vacuum of 10 -4} to 10 ^{-1 torr.}

The PbTe-AgSbTe ₂ compound has a structure in which PbTe forms a matrix, and AgSbTe ₂ nanostructures are dispersed in a PbTe matrix.

The PbTe-AgSbTe _2- based compound may exhibit a relative density higher than 99%.

The PbTe-AgSbTe _2- based compound may exhibit a thermal conductivity lower than 1.33 W/mK.

_{Hereinafter, a PbTe-AgSbTe 2-} based compound according to a preferred embodiment of the present invention will be described in more detail.

_{The PbTe-AgSbTe 2} based compound according to a preferred embodiment of the present invention has a structure in which PbTe forms a matrix and AgSbTe ₂ nanostructures are dispersed in a PbTe matrix.

The PbTe-AgSbTe _two- based compound may consist of Ag, Pb, Sb, and Te constituting a chemical composition in a molar ratio of 1 to 5:18:1 to 5:20 (a molar ratio of Ag:Pb:Sb:Te). .

The PbTe-AgSbTe _2- based compound is a highly densified compound having a relative density higher than 99%.

The AgSbTe ₂ nanostructure (nanostructure) has a circular shape and forms interfaces while having coherent geometries with the PbTe matrix. This interface is more effective to act as phonon scattering sources and significantly lowers the overall thermal conductivity. The _{PbTe-AgSbTe 2 compound, in which AgSbTe 2} nanostructures are well dispersed in the PbTe matrix, exhibits thermal conductivity lower than 1.33 W/mK, more specifically, thermal conductivity of 0.9 to 1.3 W/mK, and AgSbTe ₂ nanostructures ( The thermal conductivity can be controlled according to the crystal distribution and size of the nanostructure).

_{Hereinafter, a method for preparing a PbTe-AgSbTe two-} based compound according to a preferred embodiment of the present invention will be described in more detail.

Ag, Pb, Sb and Te are mixed. It is preferable to mix Ag, Pb, Sb and Te in a molar ratio of 1-5:18:1-5:20.

A mixture of Ag, Pb, Sb and Te is placed in a container, evacuated to achieve a vacuum state inside the container, and purged while injecting an inert gas into the container. The container may use a quartz tube (quartz tube) that can withstand the melting temperature to be described later. It is preferable to exhaust the inside of the container ^{to achieve a vacuum of 10 -4} to 10 ^{-1 torr.} The inert gas may be argon (Ar), helium (He), or a mixture thereof.

The inside of the vessel is filled with an inert gas and sealed. By filling the inside of the container with an inert gas and sealing it, it is possible to suppress oxidation of Ag, Pb, Sb and Te during the high-temperature melting process. The inert gas may be argon (Ar), helium (He), or a mixture thereof.

The mixture of Ag, Pb, Sb and Te contained in the vessel is melted. The melting can be carried out while the vessel is charged in a rocking furnace and the vessel is rocked. There is an advantage in that homogenization and melting can be achieved by performing melting while rocking in a rocking furnace. The melting is preferably carried out at a temperature of about 960 to 1150 °C, more preferably about 960 to 1100 °C. The melting is preferably performed for 10 minutes to 48 hours, more preferably 1 to 24 hours.

Allow the molten result to be quenched. It is preferable to unload the container containing the melt from the rocking furnace and allow it to be rapidly cooled to room temperature.

The quenched result is heat treated. A container containing the quenched product is charged into a furnace, and after performing the heat treatment, the furnace is cooled, and the heat treated product is taken out from the container. The heat treatment is preferably performed at a temperature of 200 to 750 °C, more preferably 250 to 700 °C. The heat treatment is preferably performed for 10 minutes to 48 hours, more preferably 1 to 24 hours.

The PbTe-AgSbTe ₂ compound thus prepared has a structure in which PbTe forms a matrix, and AgSbTe ₂ nanostructures are dispersed in the PbTe matrix. The PbTe-AgSbTe _2- based compound may exhibit a relative density higher than 99%. The PbTe-AgSbTe _2- based compound may exhibit a thermal conductivity lower than 1.33 W/mK.

Hereinafter, experimental examples according to the present invention are specifically presented, and the present invention is not limited to the experimental examples presented below.

Due to its direct and narrow band-gap characteristics, PbTe-based compounds are being actively studied for application to infrared detectors, light-emitting devices, and thermoelectric devices using highly reliable materials. have.

It is predicted that the theoretical thermoelectric properties of the PbTe-based compound will be greatly improved near 800 K. Most of the PbTe-based compounds were studied by focusing on the improvement of the charge concentration and the control of thermal conductivity by applying the element substitution method. In addition, compounds with improved thermoelectric properties have been developed using n-type or p-type doping or band structure engineering. Research on improving thermoelectric properties by using point defects in the atomic scale is also being conducted. Such a doping or nanostructuring method is a method of maximizing thermoelectric properties by minimizing thermal conductivity and maintaining electrical conductivity. However, although studies for synthesizing nanostructures (nanostructures) in PbTe-based compounds have been actively conducted, the synthesis was difficult due to constraints such as high solubility of nanostructures and narrowing of the existence temperature range.

_{Experimental examples show that the thermoelectric properties can be selectively controlled by dispersing AgSbTe 2} nanoparticles in the PbTe-based compound material and forming a homogeneous interface between the matrix and the nanoparticles. _{In addition, by applying the AgSbTe 2} phase existing in a specific temperature range of 360 ~ 575 ℃ to the PbTe-based compound, it was analyzed that the section where the nanostructure (nanostructure) was formed was expanded to 250 ~ 700 ℃. The significance of this nanostructure (nanostructure) is that it can be applied to various chalcogen compounds by clearly identifying the growth and phase separation mechanisms from particle nucleation, and can be selectively used to develop new materials that can control the efficiency of thermal energy. It can be said that there is

<Experimental Example 1>

Pb, Te, Ag and Sb (Alfa Aesar, granules, 99.99%) were prepared and _{mixed in a composition of AgPb m} SbTe _m+2 (m=18). More specifically, Ag, Pb, Sb and Te were mixed to form a molar ratio of 1:18:1:20.

A mixture of Ag, Pb, Sb, and Te is charged into a carbon-coated quartz tube, the inside of the quartz tube ^{is created in a vacuum of about 10 -3} torr, and Ar gas is introduced into the quartz tube. It was purged while injecting.

In order to suppress the oxidation of Ag, Pb, Sb, and Te during the high-temperature melting process, the inside of the quartz tube was filled with Ar gas and then sealed.

A sealed quartz tube is charged into a rocking furnace, homogenized and melted at 960° C. for 10 hours while the quartz tube is oscillated, and then quenched to room temperature (room temperature). did.

The molten product was taken out of the quenched quartz tube to obtain a _{PbTe-AgSbTe 2-based compound.}

<Experimental Example 2>

Pb, Te, Ag and Sb (Alfa Aesar, granules, 99.99%) were prepared and _{mixed in a composition of AgPb m} SbTe _m+2 (m=18). More specifically, Ag, Pb, Sb and Te were mixed to form a molar ratio of 1:18:1:20.

A mixture of Ag, Pb, Sb, and Te is charged into a carbon-coated quartz tube, the inside of the quartz tube ^{is created in a vacuum of about 10 -3} torr, and Ar gas is introduced into the quartz tube. It was purged while injecting.

In order to suppress the oxidation of Ag, Pb, Sb, and Te during the high-temperature melting process, the inside of the quartz tube was filled with Ar gas and then sealed.

A sealed quartz tube is charged into a rocking furnace, homogenized and melted at 960° C. for 10 hours while the quartz tube is oscillated, and then quenched to room temperature (room temperature). ) was done.

A quenched quartz tube was charged into a furnace, and after heat treatment at 250° C. for 10 hours, furnace cooling was performed.

After cooling the furnace, the quartz tube was unloaded, and the heat-treated product was taken out of the quartz tube to obtain a _{PbTe-AgSbTe 2-based compound.}

<Experimental Example 3>

Pb, Te, Ag and Sb (Alfa Aesar, granules, 99.99%) were prepared and _{mixed in a composition of AgPb m} SbTe _m+2 (m=18). More specifically, Ag, Pb, Sb and Te were mixed to form a molar ratio of 1:18:1:20.

A mixture of Ag, Pb, Sb, and Te is charged into a carbon-coated quartz tube, the inside of the quartz tube ^{is created in a vacuum of about 10 -3} torr, and Ar gas is introduced into the quartz tube. It was purged while injecting.

In order to suppress the oxidation of Ag, Pb, Sb, and Te during the high-temperature melting process, the inside of the quartz tube was filled with Ar gas and then sealed.

A sealed quartz tube is charged into a rocking furnace, homogenized and melted at 960° C. for 10 hours while the quartz tube is oscillated, and then quenched to room temperature (room temperature). ) was done.

A quenched quartz tube was charged into a furnace, and after heat treatment at 450° C. for 10 hours, furnace cooling was performed.

After cooling the furnace, the quartz tube was unloaded, and the heat-treated product was taken out of the quartz tube to obtain a _{PbTe-AgSbTe 2-based compound.}

<Experimental Example 4>

Pb, Te, Ag and Sb (Alfa Aesar, granules, 99.99%) were prepared and _{mixed in a composition of AgPb m} SbTe _m+2 (m=18). More specifically, Ag, Pb, Sb and Te were mixed to form a molar ratio of 1:18:1:20.

A mixture of Ag, Pb, Sb, and Te is charged into a carbon-coated quartz tube, and the inside of the quartz tube ^{is created in a vacuum of about 10 -3} torr, and Ar gas is introduced into the quartz tube. It was purged while injecting.

In order to suppress the oxidation of Ag, Pb, Sb, and Te during the high-temperature melting process, the inside of the quartz tube was filled with Ar gas and then sealed.

A sealed quartz tube is charged into a rocking furnace, homogenized and melted at 960° C. for 10 hours while the quartz tube is oscillated, and then quenched to room temperature (room temperature). ) was done.

A quenched quartz tube was charged into a furnace, and after heat treatment at 600° C. for 10 hours, furnace cooling was performed.

After cooling the furnace, the quartz tube was unloaded, and the heat-treated product was taken out of the quartz tube to obtain a _{PbTe-AgSbTe 2-based compound.}

<Experimental Example 5>

Pb, Te, Ag and Sb (Alfa Aesar, granules, 99.99%) were prepared and _{mixed in a composition of AgPb m} SbTe _m+2 (m=18). More specifically, Ag, Pb, Sb and Te were mixed to form a molar ratio of 1:18:1:20.

A mixture of Ag, Pb, Sb, and Te is charged into a carbon-coated quartz tube, the inside of the quartz tube ^{is created in a vacuum of about 10 -3} torr, and Ar gas is introduced into the quartz tube. It was purged while injecting.

In order to suppress the oxidation of Ag, Pb, Sb, and Te during the high-temperature melting process, the inside of the quartz tube was filled with Ar gas and then sealed.

A sealed quartz tube is charged into a rocking furnace, homogenized and melted at 960° C. for 10 hours while the quartz tube is oscillated, and then quenched to room temperature (room temperature). ) was done.

A quenched quartz tube was charged into a furnace, and after heat treatment at 650° C. for 10 hours, furnace cooling was performed.

After cooling the furnace, the quartz tube was unloaded, and the heat-treated product was taken out of the quartz tube to obtain a _{PbTe-AgSbTe 2-based compound.}

<Experimental Example 6>

Pb, Te, Ag and Sb (Alfa Aesar, granules, 99.99%) were prepared and _{mixed in a composition of AgPb m} SbTe _m+2 (m=18). More specifically, Ag, Pb, Sb and Te were mixed to form a molar ratio of 1:18:1:20.

A mixture of Ag, Pb, Sb, and Te is charged into a carbon-coated quartz tube, the inside of the quartz tube ^{is created in a vacuum of about 10 -3} torr, and Ar gas is introduced into the quartz tube. It was purged while injecting.

In order to suppress the oxidation of Ag, Pb, Sb, and Te during the high-temperature melting process, the inside of the quartz tube was filled with Ar gas and then sealed.

A sealed quartz tube is charged into a rocking furnace, homogenized and melted at 960° C. for 10 hours while the quartz tube is oscillated, and then quenched to room temperature (room temperature). ) was done.

A quenched quartz tube was charged into a furnace, and after heat treatment at 700° C. for 10 hours, furnace cooling was performed.

After cooling the furnace, the quartz tube was unloaded, and the heat-treated product was taken out of the quartz tube to obtain a _{PbTe-AgSbTe 2-based compound.}

The compounds prepared according to Experimental Examples 1 to 6 were subjected to characterization by cutting, grinding, and polishing.

For the compounds prepared according to Experimental Examples 1 to 6, the density was measured using the Archimedes' principle.

In order to confirm the phase of the compound prepared according to Experimental Examples 1 to 6, the crystal phase was analyzed using X-ray diffraction (XRD).

Microstructures of the compounds prepared according to Experimental Examples 1 to 6 were observed using a scanning electron microscope (SEM) (JEOL, JSM-7100F Aztec), and thermoelectric analysis was performed using ZEM3.

Thermal analysis of the compounds prepared according to Experimental Examples 1 to 6 was performed using a NETZSCH LFA467 instrument to measure thermal diffusivity.

The thermal diffusivity of a material is determined by the rate at which heat propagates by its intrinsic conductivity during temperature change over time. Materials with high thermal diffusivity have a fast heat propagation. Thermal conductivity (λ) is a function of thermal diffusivity (α), specific heat (C _p ), and density (d) is defined as in Equation 1 below.

[Equation 1]

A representative method for measuring thermal diffusivity is a laser flash method. After stabilizing the material at the temperature to be analyzed, one side of the material is heated using an instantaneous energy pulse (energy source such as laser), and the temperature change on the opposite side of the material is analyzed and recorded over time. Assuming no heat loss, assuming isotropic and insulating materials, Parker proposed a method for calculating thermal diffusivity. The thermal diffusivity is determined by recording the temperature change. The thermal diffusivity is defined by the following Equation 2 by the thickness (L) of the material and the time (t _{1/2 ) for the opposite surface to reach the middle of the maximum temperature.}

[Equation 2]

The relationship of Equation 2 above assumes an ideal condition of an insulating material and instantaneous pulse heating. Therefore, modified conditions according to the experimental environment were proposed. For example, heat loss, limitation of pulse heating duration, non-constant pulse heating, complex or non-uniform structures, etc. are controlled by variables.

1 is a diagram showing an X-ray diffraction (XRD; X-ray diffraction) pattern of a _{PbTe-AgSbTe 2-} based compound prepared according to Experimental Example 1. FIG. In FIG. 1, (a) shows a PbTe compound as a reference, and (b) shows a PbTe-AgSbTe _2- based compound prepared according to Experimental Example 1.

2 is a view showing X-ray diffraction (XRD; X-ray diffraction) patterns of _{PbTe-AgSbTe 2-} based compounds prepared according to Experimental Examples 2 to 6; In FIG. 2, (a) shows a PbTe compound as a reference, (b) shows a PbTe-AgSbTe _2- based compound prepared according to Experimental Example 2, (c) is a PbTe- prepared according to Experimental Example 3 AgSbTe ₂ represents the compound, (d) represents the PbTe-AgSbTe ₂ based compound prepared according to Experimental Example 4, (e) represents the PbTe-AgSbTe ₂ based compound prepared according to Experimental Example 5, (f) _{represents a PbTe-AgSbTe 2-} based compound prepared according to Experimental Example 7.

1 and 2, as a result of X-ray diffraction (XRD) analysis, it was analyzed that a PbTe compound having a single-phase NaCl structure was formed, and it was determined that the structure was maintained even after heat treatment. In addition, it was determined that Ag-Sb related compounds were not formed.

The lattice constant (Lattice parameter) and density of _{the PbTe-AgSbTe 2-} based compounds prepared according to Experimental Example 1, Experimental Example 2, Experimental Example 3, Experimental Example 5 and Experimental Example 6 were measured and shown in Table 1 below.

compounds Experimental Example 1 Experimental example Experimental Example 6 Experimental Example 5 Experimental Example 3 Experimental Example 2 Lattice parameter (Å) 6.4432 6.4295 6.4386 6.4114 6.4137 Relative lattice parameter (%) 99.71 99.49 99.64 99.21 99.25

Referring to Table 1, as a result of the density measurement, the compounds were analyzed to have a relative density of 99% or more, and were determined to be highly densified compounds.

_{3a is a transmission electron microscope (TEM) photograph showing the PbTe-AgSbTe 2-} based compound prepared according to Experimental Example 6, and FIG. 3b is a transmission electron microscope (TEM) photograph showing the _{PbTe-AgSbTe 2-based compound prepared according to Experimental Example 5} It is an electron microscope (TEM) photograph, and FIG. 3c is a transmission electron microscope (TEM) photograph showing _{the PbTe-AgSbTe 2-based compound prepared according to Experimental Example 3.} 4 is a view showing the results of analyzing the size distribution of a nanostructure based on a transmission electron microscope. 4, (a) is for the PbTe-AgSbTe _2- based compound prepared according to Experimental Example 3, (b) is for the PbTe-AgSbTe _2- based compound prepared according to Experimental Example 5, (c) is the experiment It relates to the PbTe-AgSbTe _2- based compound prepared according to Example 6.

3A to 4 , the PbTe-AgSbTe ₂ based compound has _{a structure in which AgSbTe 2} nanostructures are dispersed in a PbTe matrix. The shape of the AgSbTe ₂ nanostructure (nanostructure) was analyzed as being circular and forming interfaces while having a PbTe matrix and coherent geometries, and it was determined that it was well dispersed. . This interface is more effective to act as phonon scattering sources and significantly lowers the overall thermal conductivity.

Figure 5a is a graph showing the total thermal conductivity (total thermal conductivity) according to the temperature of the _{PbTe-AgSbTe 2-} based compound prepared according to Experimental Example 1, Experimental Example 2, Experimental Example 3, Experimental Example 5, and Experimental Example 6; 5b is a graph showing the lattice thermal conductivity _{of the PbTe-AgSbTe 2-} based compounds prepared according to Experimental Example 1, Experimental Example 2, Experimental Example 3, Experimental Example 5, and Experimental Example 6.

5A and 5B, as a result of the analysis of thermal conductivity, in the case of Experimental Example 1, 1.33 W/mK at room temperature was shown, whereas in the case of Experimental Example 6 heat-treated at 700° C., 1.09 W/mK and heat treatment at 650° C. Experimental Example 5 showed the lowest thermal conductivity of 0.92 W/mK.

As a result of calculating and comparing the lattice thermal conductivity, it was analyzed that the heat-treated compound at 650 ° C, in which _{AgSbTe 2 is well distributed, showed the lowest thermal conductivity.} is considered to be reliably controlled.

As mentioned above, although preferred embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various modifications are possible by those skilled in the art.

Claims (14)

PbTe forms a matrix,
AgSbTe _{2 PbTe-AgSbTe 2} based compound, characterized in that the nanostructure is dispersed in a PbTe matrix.
The PbTe-AgSbTe according to claim 1, wherein the PbTe-AgSbTe _2- based compound comprises Ag, Pb, Sb and Te in a molar ratio of 1 to 5:18:1 to 5:20. ₂ compound.
The method of claim 1, wherein the AgSbTe ₂ PbTe-based compound AgSbTe ₂ PbTe-based compound, characterized in that indicating a relative density higher than 99%.
The method of claim 1, wherein the AgSbTe ₂ PbTe-based compound AgSbTe ₂ PbTe-based compound, characterized in that indicating the lower thermal conductivity than 1.33 W / mK.
(a) mixing Ag, Pb, Sb and Te;
(b) putting a mixture of Ag, Pb, Sb and Te into a container, evacuating the inside of the container to achieve a vacuum state, and purging while injecting an inert gas into the container;
(c) filling and sealing the inside of the container with an inert gas;
(d) melting a mixture of Ag, Pb, Sb and Te contained in the vessel;
(e) allowing the molten product to be quenched; and
(f) a method for producing _{a PbTe-AgSbTe 2-} based compound comprising the step of heat-treating the quenched product.
The method of claim 5, wherein the Ag, Pb, Sb and Te 1~5: 18: 1~5: PbTe -AgSbTe process for producing a _2-based compound comprising a step of mixing to achieve a molar ratio of 20.
The method of claim 5, wherein the melt is a PbTe-AgSbTe process for producing a _2-based compound characterized in that at a temperature of 960~1150 ℃.
The method of claim 5, wherein in step (d),
A method for producing _{a PbTe-AgSbTe 2-} based compound, characterized in that the melting is performed while the vessel is charged in a rocking furnace and the vessel is shaken.
The method of claim 5, wherein the heat treatment is a PbTe-AgSbTe process for producing a _2-based compound, characterized in that performing at a temperature of 200~750 ℃.
6. The method of claim 5, PbTe-AgSbTe process for producing a _2-based compounds characterized by using a quartz tube (quartz tube) in the container.
The method of claim 5, wherein in step (b),
A method for producing _{a PbTe-AgSbTe 2-} based compound, characterized in that the interior of the vessel is evacuated to achieve a vacuum ^{of 10 -4} to 10 ^{-1 torr.}
The method of claim 5, wherein the PbTe-AgSbTe ₂ based compound PbTe is forms a matrix (matrix), AgSbTe PbTe-AgSbTe ₂ system characterized in that the _second nanostructure forms a structure which is dispersed in the PbTe matrix (matrix) A method for preparing a compound.
The method of claim 5, wherein the PbTe-AgSbTe ₂ PbTe-based compound AgSbTe process for producing a _2-based compound, characterized in that indicating a relative density higher than 99%.
The method of claim 5, wherein the PbTe-AgSbTe ₂ PbTe-based compound AgSbTe process for producing a _2-based compound, characterized in that indicating lower thermal conductivity than 1.33 W / mK.

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