JP5190842B2 - Measuring device for thermal permeability - Google Patents

Description

The present invention relates to a thermal osmosis rate measuring apparatus that measures a temperature in a thermal probe using a thermal probe.

  A thermoelectric conversion material is a material that directly converts energy between heat and electricity. When a temperature difference is given to this material, a potential difference is generated inside the material. Therefore, if this potential difference is taken out to an external circuit, electric power can be taken out at the external load portion, which can be used for a power generation system using the temperature difference.

  In recent years, it has been proposed to reuse waste heat from the viewpoint of environmental problems. In order to reuse waste heat and convert it into electrical energy, it is required to develop a thermoelectric conversion material with high thermoelectric efficiency that can convert a large amount of heat into electricity. Samples produced in the development stage of thermoelectric conversion materials may have non-homogeneous sample materials or sample shapes that cannot be measured by general measurement methods. Accordingly, there is a need for development of an apparatus that can verify the homogeneity of a sample and can evaluate a sample that cannot be evaluated by a general measurement method, and an evaluation method thereof.

  In addition, the functionally gradient material has a gentle distribution in the sample. By making a gradient composition using a plurality of materials, a new material having multiple functions can be developed, which may lead to a new product development. For example, it is possible to develop a product in which the heat conduction characteristics and the thermoelectromotive force characteristics are in a desired state by producing a sample in which the thermophysical property values are gently distributed. In order to confirm the distribution of thermophysical property values, it is necessary to develop an apparatus capable of measuring the thermophysical property values in a minute region.

  As a technique related to the measurement of thermophysical properties in a minute region, for example, a method of measuring a thermal permeability by applying a periodic heating method and a thermoreflectance technique (see, for example, Non-Patent Document 1 and Patent Document 1), AFM SThM technology that measures thermal images using the technology (see, for example, Non-Patent Document 2) and STP method that collects temperature information on the sample surface using a thermocouple with a thin tip as a cantilever and uses it for surface shape measurement ( For example, the nonpatent literature 3 reference) etc. are proposed. A plurality of thermophysical property measurement methods using thermal probes have been proposed (see, for example, Non-Patent Documents 4 and 5, Patent Documents 2 and 3). An apparatus based on the above method has been developed.

JP 2000-121585 A JP 2004-003872 A JP 2008-057144 A Thermal effusivity distribution measurements using a thermo-reflectance technique; in Proceeding of 10th International Conference of Photo-acoustic and Photothermal Phenomena, pp. 315-317 (1999); N. Taketoshi, M. Ozawa, H. Ohta, and T. Baba . Scanning Near-Field Optical Microscopy and Scanning Thermal Microscopy; Jpn. J. Appl.Phys. Vol. 33, p.p.3785-3790 (1994); R. J. Pylkki, P. J. Moyer, and P. E. West. Scanning Thermal Profiler; Appl. Phys. Lett., Vol. 49, No23, pp. 1587-1589 (1986); C. C. Williams and H. K. Wickamasinghe. Measurement method of three-constant thermal solids using a point contact temperature probe (measurement theory); Thermophysical properties, 13, 4, pp.246-251; Ichiro Takahashi, Masami Sasamori. Measurement method of three-state solid heat using a point contact temperature probe (examination of measured object shape and measurement conditions); Thermophysical properties, 13, 4, pp.252-257; Ichiro Takahashi, Masami Sasamori.

  The subject of this invention is providing the measuring device of the thermal osmosis rate based on the measuring method of the voltage and / or temperature of several points, the evaluation method of contact point temperature, and the evaluation method of thermal osmosis rate.

  When evaluating the Seebeck coefficient and thermal permeability of a micro area, the present inventors use a measuring device equipped with a thermal probe, a method for measuring voltage and / or temperature at a plurality of points, a method for evaluating a contact point temperature, By constructing an apparatus based on the evaluation method of the thermal permeability, the present invention was completed by obtaining knowledge that can be measured with high accuracy.

Measuring device Ze Bekku coefficient and thermal effusivity includes a conductive sample stage made of the body which the sample is placed placed, drawn from the sample stage and the sample base line of the sample stage and the same material, placing the sample stage A conductor-made thermal probe to be brought into contact with the placed sample, a probe wire drawn from the thermal probe and made of the same material as the thermal probe, and a probe measurement line drawn to measure temperatures at a plurality of points in the thermal probe And means for measuring the Seebeck coefficient and the thermal permeability by measuring the temperature at a plurality of points in the thermal probe and the voltage at the contact point between the thermal probe and the sample before and after contact between the thermal probe and the sample. It is characterized by.

Then, before Symbol probe supporting stage for movably supported within an arbitrary plane thermal probe, a sample stage supporting stage reciprocating movably supported in a direction perpendicular to the sample stage plane is year thermal probe moves It is provided with.

Further, in the prior SL thermal probe, the contact sensing means is provided for detecting the contact between the sample, the probe support stage includes imaging means for setting a measurement region by photographing the sample stage side It is characterized by being.

The thermal osmosis rate measuring apparatus according to the first aspect of the present invention for solving the above-described problem includes a sample stage on which a sample is placed and placed, and a thermal probe that is brought into contact with the sample placed on the sample stage. A probe measurement line drawn to measure the temperature of a plurality of points in the thermal probe; and the temperature of the plurality of points in the thermal probe after the contact between the thermal probe and the sample ; And a means for measuring the thermal permeability by the temperature difference between adjacent sections .

And the thermal osmosis rate measuring device of the present invention according to claim 2 is the thermal osmosis rate measuring device according to claim 1 , wherein the thermal probe is movably supported in an arbitrary plane. And a sample stage support stage that supports the sample stage so as to be reciprocally movable in one direction orthogonal to a plane on which the thermal probe moves.

According to a third aspect of the present invention, there is provided the thermal osmosis rate measuring apparatus according to the second aspect of the present invention, wherein the thermal probe includes a contact detection means for detecting contact with the sample. The probe support stage is provided with an imaging means for imaging the sample stage side and setting a measurement region.

In the thermal osmosis rate measuring apparatus according to the present invention, the probe support stage and the sample stage support stage are controlled to move, and the thermal probe can be moved to an arbitrary relationship with respect to the sample stage to bring the thermal probe into contact with the sample. it can. Further, by grasping the contact state by the contact detection means, the thermal probe can be brought into contact with the sample even when the sample is changed, and measurement can be performed by setting the measurement region by the imaging means.

The thermal osmosis rate measuring apparatus of the present invention can accurately measure the distribution of the thermal osmosis rate.

FIG. 1 is a front view of a Seebeck coefficient and thermal osmosis rate measuring device (thermal osmosis rate measuring device) according to an embodiment of the present invention, and FIG. 2 is a view taken along line II-II in FIG. Shows a concept schematically showing the relationship between the thermal probe and the sample stage.

As shown in FIG. 1 and FIG. 2, as a thermal osmosis measurement device, the base 2 of the Seebeck coefficient and thermal osmosis measurement device 1 is provided with an X axis stage 3 and a Y axis stage 4. The X-axis stage 3 and the Y-axis stage 4 are arranged extending in directions orthogonal to each other.

  As shown in FIG. 1, an X-axis moving base 5 is supported on the X-axis stage 3 so as to be movable in the X-axis direction (left-right direction in FIG. 1), and the X-axis moving base 5 is driven by a drive mechanism (not shown). 3 is reciprocally movable along the line 3. A sample table 6 is attached to the X-axis moving base 5, and a sample 7 is placed on the sample table 6 in contact therewith.

  As shown in FIG. 2, a Y-axis moving base 8 is supported on the Y-axis stage 4 so as to be movable in the Y-axis direction (left and right in FIG. 2). The Y-axis moving base 8 is supported by a drive mechanism (not shown). 4 is reciprocally movable along the line 4. A Z-axis stage 9 is erected on the Y-axis movement base 8, and a Z-axis movement base 10 (probe stage) is placed on the surface of the Z-axis stage 9 on the X-axis stage 3 side in the Z-axis direction (vertical direction in FIG. 2). It is supported to move freely. The Z-axis movement base 10 can be reciprocated up and down along the Z-axis stage 9 by a drive mechanism (not shown).

  That is, the Y-axis stage 4 and the Z-axis stage 9 constitute a probe stage that supports a thermal probe, which will be described later, movably in an arbitrary plane (in the YZ plane). The X-axis stage 3 constitutes a sample stage support stage that supports a later-described thermal probe so as to be reciprocally movable in one direction orthogonal to the YZ plane.

  As shown in FIGS. 1 and 2, a support base 11 is fixed to the Z-axis movement base 10, and a probe block 13 is attached to the support base 11 via contact detection means 12. The probe block 13 is provided with a probe 14 made of the same material as the probe block 13, and the probe 14 comes into contact with the sample 7 when the Z-axis moving base 10 is lowered. The thermal probe includes a contact detection unit 12, a probe block 13, and a probe 14.

  A camera support 15 is fixed to the Z-axis movement base 10, and a sample camera 16 as an imaging unit is attached to the camera support 15. The sample camera 16 captures the sample 7, and a specific region in the image is set for the sample image captured by the sample camera 16 to be a set range for thermophysical property evaluation.

  The configuration of the thermal probe will be described with reference to FIG.

The thermal probe is composed of a probe block 13 (material A: for example, constantan) and a probe 14 (material A: for example, constantan). The probe block 13 and the probe 14 move together during measurement. The temperature (T _pb ) of the probe block 13 and the temperature (T _sb ) of the sample _stage 7 (material B: copper, for example) are kept constant during measurement by a temperature control means (not shown).

With the sample 7 and the tip of the probe 14 not in contact with each other, the temperature (T _pb ) of the probe block 13 and the temperature (T _sb ) of the sample _stage 7 are controlled. At this time, control is performed so as to satisfy the relationship of T _pb ≧ T _sb + 10 ° C. This is to make the tip of the probe 14 sufficiently higher than the temperature of the sample 7.

  The measurement is started in a state where the probe 14 of the thermal probe and the sample 7 are not in contact with each other, and after a certain period of time, the tip of the probe 14 and the sample 7 are brought into contact with each other. After the contact for a certain time, the probe 14 of the thermal probe is separated from the sample 7, and voltage measurement and temperature measurement in the probe 14 are performed during the measurement.

  A sample stage wiring 22 (material B: for example, copper) for voltage measurement is drawn from the sample stage 6 for measurement, and a probe wiring 21 (material A: for example, constantan) is drawn from the probe block 13. The sample stage wiring 22 and the probe wiring 21 are connected by a measuring means 31. Therefore, since the space between the probe wiring 21 and the sample stage wiring 22 can function as a thermocouple, temperature measurement and voltage measurement at the contact point can be performed.

The temperature in the probe 14 is measured at three points T ₁ , T ₂ , and T ₃ . From T ₁ , T _2, and T ₃ in the probe 14, voltage / temperature measurement wirings (material C: for example, chromel) 32 a, 32 b, and 32 c are drawn out for measurement (probe measurement lines). ). The wirings 32a, 32b, and 32c are connected to the probe wiring 21 by the measuring means 31, respectively. Therefore, the temperature of T ₁ , T ₂ and T ₃ can be measured as a Chromel-Constantan E thermocouple.

  An operation of measurement by the above-described Seebeck coefficient and thermal permeability measurement device 1 will be described.

  For example, the sample 7 is placed in contact with the sample stage 6, the X-axis movement base 5, the Y-axis movement base 8 and the Z-axis movement base 10 are moved as appropriate, and the measurement range is determined by photographing the sample 7 with the sample camera 16. To do. The X-axis movement base 5, the Y-axis movement base 8, and the Z-axis movement base 10 are appropriately moved, the probe 14 is positioned immediately above the measurement position of the sample 7, and temperature measurement at a plurality of points in the probe 14 is started. The Z-axis moving base 10 is lowered to bring the probe 14 into contact with the sample 7 and the voltage at the time of contact is measured. The determination of contact is made based on a change in the detection value of the contact detection means 12.

  When measuring a large number of locations on the sample 7, the X-axis moving base 5, the Y-axis moving base 8 and the Z-axis moving base 10 are appropriately moved, and the contact of the probe 14 with the sample 7 is repeated within the set range of the thermal property evaluation. The temperature of a plurality of points in the probe 14 and the voltage at the contact point are measured at a corresponding place in the set range. The measurement at multiple locations (contact of the probe 14 with the sample 7) is performed at multiple locations by controlling the descending amount of the probe 14 (movement amount of the Z-axis movement base 10).

  As a result, the temperature measurement at a plurality of points in the probe 14 and the voltage at the contact points are measured in order to obtain the Seebeck coefficient and the thermal permeability distribution of the micro area with respect to the sample 7.

As shown in FIG. 3, the method for measuring the Seebeck coefficient of an unknown sample uses a measurement system of a thermal probe (material A), a sample stage 6 (material B), and an unknown sample (sample 7: material D). Here, the measured voltage ΔV at the contact point can be expressed by the following equation (1).

In equation (1), S _b is the Seebeck coefficient of the sample _stage 6 (sample stage wiring 22), T _bd is the contact temperature between the sample _stage 6 and the sample 7, T _j is the temperature of the measuring means 31, and S _d is the temperature of the sample 7. Seebeck _{coefficient, T cpcal} the contact point temperature, _{S a} represents the Seebeck coefficient of the probe block 13 (probe wiring 21).

The Seebeck coefficient of the _{sample stage} 6 (sample stage wiring 22: material B) and the probe 14 (probe block 13, probe wiring 21: material A) is known, and the temperature T _{cpcal of the} contact point is the temperature at a plurality of points in the probe. Based on the measurement and the measurement result of the reference sample 7 (material B) of the same material on the sample stage 6, the temperature T _j of the measuring means 31 is measured, and the contact temperature T _bd between the sample _stage 6 and the sample 7 is measured. If the control temperature T _sb is 6, the Seebeck coefficient of the unknown sample can be estimated by the following equation (2).

  Further, the thermal permeability for the unknown sample 7 is evaluated by measuring the temperature at a plurality of points in the probe 14 of FIG. The temperature difference ΔT in the adjacent section in the probe 14 after contact corresponds to the thermal permeability b of the sample 7, and the relationship between the thermal permeability b and the temperature difference ΔT can be expressed by the following equation (3). it can.

In the formula (3), c ₁ , c ₂ , and c ₃ are constants.

Further, if the volume specific heat capacity C (density and specific heat capacity) of the sample 7 is measured by a known method, the above-described heat permeability b can be converted into the heat conductivity λ by the equation (4). That is, the thermal conductivity of the unknown sample can be estimated from the thermal permeability b measured for the unknown sample.

  Thereby, the thermal conductivity of the sample 7 (unknown sample) can be estimated from the thermal permeability b measured for the sample 7 (unknown sample). As an actual apparatus, it is possible to display the thermal conductivity of the unknown sample 7 by incorporating the conversion formula (4).

  In the measurement at a plurality of points, the Seebeck coefficient and the thermal permeability are evaluated by the above measurement at all points, and are evaluated as values at each measurement position.

Using the apparatus described above, 600 μm × 1500 μm (Bi ₂ Te ₃ ) _1-x (SbTe) _x is used as a sample, and distribution measurement is performed at 30 μm intervals, thereby obtaining the results shown in FIGS. did it.

FIG. 4 shows a situation in which the numerical distribution of the value of the Seebeck coefficient Sd (μVK ⁻¹ ) is represented by shading, and the Seebeck coefficient (μVK ⁻¹ ) decreases as the shading state becomes deeper. FIG. 5 is a situation in which the numerical distribution of the value of the thermal permeability b (Js− ^0.5 m ⁻² K ⁻¹ ) is represented by shading, and the thermal permeability (Js ^{−0. 5} m ⁻² K ⁻¹ ) is small.

FIG. 6 shows a numerical distribution of values of thermal conductivity λ (Wm ⁻¹ K ⁻¹ ) determined using a volume specific heat capacity (1.36 × 10 ⁶ Jm ⁻³ K ⁻¹ ) evaluated by a known method. The thermal conductivity λ (Wm ⁻¹ K ⁻¹ ) decreases as the density becomes darker.

The average value and standard deviation of the measurement results are as follows: Seebeck coefficient S _d is 161 ± 22 μVK ⁻¹ , thermal permeability b is 1360 ± 120 Js ^−0.5 m ⁻² K ⁻¹ , and thermal conductivity λ is 1 37 ± 2.4 Wm ⁻¹ K ⁻¹ .

  By using the apparatus of the present invention, it can be used in terms of material exploration and homogeneity evaluation when developing a material useful in the technical field using a thermoelectric conversion material having a high thermoelectric conversion efficiency. In addition, the thermophysical property distribution of the functionally gradient material can be obtained, which leads to the promotion of new material development.

It is a front view of the thermophysical property evaluation apparatus which concerns on the example of 1 embodiment of this invention. It is the II-II arrow directional view in FIG. It is the conceptual diagram which represented typically the relationship between a thermal probe and a sample stand. It is a conceptual diagram showing distribution of Seebeck coefficient. It is a conceptual diagram showing distribution of the heat permeability. It is a conceptual diagram showing distribution of thermal conductivity.

DESCRIPTION OF SYMBOLS 1 Measuring apparatus 2 Base 3 X-axis stage 4 Y-axis stage 5 X-axis movement base 6 Sample stand 7 Sample 8 Y-axis movement base 9 Z-axis stage 10 Z-axis movement base 11 Support stand 12 Contact detection means 13 Probe block 14 Probe 15 Camera support
16 sample camera 21 probe wiring 22 sample base wiring 31 measuring means 32 wiring

Claims (3)

A sample stage on which the sample is placed and mounted;
A thermal probe in contact with the sample placed on the sample stage;
A probe measurement line drawn to measure the temperature of a plurality of points in the thermal probe;
Means for measuring the temperature of a plurality of points in the thermal probe after contacting the thermal probe and the sample, and measuring the thermal permeability by the temperature difference between adjacent sections in the thermal probe. Permeability measuring device. In the thermal osmosis rate measuring device according to claim 1 ,
A probe support stage for supporting the thermal probe movably in an arbitrary plane;
A thermal osmosis rate measuring apparatus comprising: a sample stage support stage that supports the sample stage so as to be reciprocally movable in one direction orthogonal to a plane in which the thermal probe moves. In the thermal osmosis rate measuring device according to claim 2 ,
The thermal probe is provided with contact detection means for detecting contact with the sample, and the probe support stage is provided with imaging means for photographing the sample stage side and setting a measurement region. A thermal osmosis rate measuring device characterized by that.