JP7658093B2 - Sample holder for measuring magnetic orientation and method for measuring magnetic orientation - Google Patents

Description

The present invention relates to a sample holder for measuring magnetic orientation and a method for measuring magnetic orientation.

Crystal orientation refers to the alignment of crystals in a specific direction due to the crystal structure. Rolled steel sheets and plating films often have crystals oriented in a certain direction. A known method for quantitatively evaluating the degree of crystal orientation in such materials is to determine it from the relative value of the X-ray diffraction peak intensity ratio of an oriented sample to that of a non-oriented sample.

In contrast, magnetic alignment rather than crystalline structure is called magnetic orientation, and magnetic materials have a magnetic orientation in a specific direction.

When a material is in powder form, the individual crystal grains are randomly present and generally not oriented, but the crystal orientation may be oriented by applying force to the sample or by compacting it. The same is true for magnetic powder samples, where fixation may result in crystal orientation, but the direction of crystal orientation does not necessarily coincide with the direction of magnetic orientation. Therefore, by using conventional fixation methods to perform X-ray diffraction, the crystal orientation of magnetic material powders can be quantitatively evaluated, but the magnetic orientation cannot be evaluated.

Under such circumstances, Patent Document 1 discloses that it is effective to use a sample holder consisting of a stage portion (called a sample stage portion in Patent Document 1) and a base portion in order to evaluate the magnetic orientation of magnetic material powder by X-ray diffraction.

In Patent Document 1, a magnet (a lump of magnet in Patent Document 1) is placed inside a container and fixed with an adhesive. This is attached to a base, and when a sample is sprinkled on the top surface of the container, the magnetic force of the magnet causes the sample to be oriented in the magnetic direction on the top surface of the container. Therefore, if an X-ray diffraction measurement is performed on a sample in a magnetically oriented state, an X-ray diffraction pattern that reflects the magnetic orientation can be observed.

JP 2003-98125 A

Through intensive research by the inventors, improvements were found in the method described in Patent Document 1. With the method described in Patent Document 1, the sample on the stage is neatly oriented in the magnetic direction at the center of the magnet placed inside the container. On the other hand, when the sample moves away from the center of the magnet, it becomes dispersed around the periphery (in other words, scattered) and oriented.

Figure 1 is a schematic diagram of a sample placed in the sample holder described in Patent Document 1.

As shown in Figure 1, the particles that make up the sample 5 tend to fall over the further they are from the center of the magnet 2.

In this state, the particles that make up the sample are dispersed on the stage 3, causing the inside of the sample 5 to become sparse. When the inside of the sample 5 becomes sparse, sufficient peak intensity cannot be obtained even when performing X-ray diffraction measurement. As a result, there is a risk that correct magnetic orientation information cannot be obtained.

The objective of the present invention is to provide a method for obtaining accurate magnetic orientation information by packing the sample closely when using a sample holder equipped with a magnet.

The inventors have thoroughly investigated the above problem. As a result, they have come up with a new configuration in which, in the configuration described in Patent Document 1, the side of the opening is provided on the stage portion and in the area directly above the magnet, and this side prevents the particles that make up the sample from scattering, i.e., correcting the position of the sample so that it is within the opening and therefore within the area directly above the magnet. A specific example of this configuration is as follows.

The first aspect of the present invention is a method for producing a cellular membrane comprising the steps of:
A sample holder for holding a sample when measuring the magnetic orientation of the sample by X-ray diffraction, comprising:
a stage portion on whose upper surface a sample is placed;
A magnet disposed on the underside of the stage portion;
A sample placement correction unit is arranged so that a side surface of an opening fits within the upper region of the magnet;
A sample holder for magnetic orientation measurement comprising:

A second aspect of the present invention is a method for producing a composition comprising the steps of:
the stage portion being formed by the outer surface of the bottom of the container;
The magnet is fixed to the inner surface of the bottom of the container;
The sample position correction unit is a ring-shaped sample holder for magnetic orientation measurement according to the first aspect, and is disposed above the magnet with the stage unit therebetween.

A third aspect of the present invention is a method for producing a composition comprising the steps of:
a sample placement step of sprinkling a sample on the sample holder according to the first or second aspect to magnetically orient the sample on the upper surface of the stage and within the opening of the sample placement correction unit;
a measuring step of performing X-ray diffraction measurement on the magnetically oriented sample and calculating the degree of magnetic orientation;
The present invention relates to a method for measuring a magnetic azimuth orientation, the method comprising the steps of:

A fourth aspect of the present invention is a method for producing a composition comprising the steps of:
The opening depth of the sample arrangement correction unit is smaller than the maximum vertical length of a particle aggregate in a state in which a plurality of particles constituting the sample are vertically connected due to magnetic orientation,
The magnetic orientation measurement method according to the third aspect further includes a smoothing step between the sample placement step and the measurement step, in which particles protruding from the opening of the sample placement correction unit are smoothed to fit onto the upper surface of the sample placement correction unit.

The present invention allows accurate magnetic orientation information to be obtained by packing the sample tightly when using a sample holder equipped with a magnet.

FIG. 1 is a schematic diagram of the sample holder described in Patent Document 1 when a sample is placed on it. FIG. 2(a) is a schematic perspective view showing the sample holder of this embodiment, and FIG. 2(b) is a schematic perspective view showing how a sample is sprinkled onto the sample holder. FIG. 3 is a schematic cross-sectional view of the sample holder of this embodiment after a sample placement step and a leveling step have been carried out in that order. FIG. 4 is a schematic plan view of the sample holder of this embodiment after a sample placement step and a smoothing step have been carried out in that order. FIG. 5(a) is a schematic cross-sectional view showing the state before the smoothing step, and FIG. 5(b) is a schematic cross-sectional view showing the state after the smoothing step. FIG. 6 is a schematic perspective view showing a state in which the container of the sample holder of this embodiment is fixed to the base portion. FIG. 7 is a schematic cross-sectional view of the modified sample holder after a sample placement step and a smoothing step are performed in that order. 8A is a schematic cross-sectional view of a modified sample holder having a magnet holder after a sample placement step and a leveling step are performed in sequence, and FIG. 8B is a schematic bottom view of the modified sample holder having a magnet holder. FIG. 9 is a graph showing the results of X-ray diffraction measurement for Example 1 and Comparative Example 1 (no magnet was used). 10 is a graph showing the results of X-ray diffraction measurement of Example 1 and Comparative Example 2 (without using the sample placement correction unit (ring)). The graph of Example 1 in FIG. 10 is the same as the graph of Example 1 in FIG. FIG. 11 is a graph showing the results of calculation of the degree of orientation (vertical axis) using eight arbitrary diffraction peaks (arranged on the horizontal axis) obtained from the measurement results of FIG. 9 for Example 1 and Comparative Example 1. FIG. 12 is a graph showing the results of calculation of the degree of orientation (vertical axis) using eight arbitrary diffraction peaks (arranged on the horizontal axis) obtained from the measurement results of FIG. 10 for Example 1 and Comparative Example 2.

The present embodiment will be described below. "-" indicates a value greater than or equal to a specified value and less than or equal to a specified value. Note that the contents not described in this specification are incorporated by reference in the contents of Patent Document 1. In addition, the up-down direction in this specification refers to the top-to-bottom direction.

Figure 2(a) is a schematic perspective view showing the sample holder 1 of this embodiment, and Figure 2(b) is a schematic perspective view showing how a sample is sprinkled onto the sample holder 1.

The sample used in this embodiment is not limited as long as it is magnetic, but a powder made up of particles is preferred because it provides excellent workability when carrying out the measurement method according to this embodiment.

This embodiment is a sample holder 1 for holding a sample when measuring the magnetic orientation of the sample by X-ray diffraction. The sample holder 1 has the following configuration.
A stage portion 3 on whose upper surface 3a a sample is placed
Magnet 2 arranged on the lower surface 3b of the stage portion 3
A sample placement correction unit 4 having an opening 4h and arranged so that the side surface of the opening 4h fits within the upper region of the magnet 2.

There are no limitations on the material or shape of the stage 3, so long as the sample can be placed on the upper surface 3a and the magnet 2 can be fixed to the lower surface 3b. However, in order to perform X-ray diffraction measurements, it is preferable to make the stage 3 out of a material that does not have crystallinity. Furthermore, if the stage 3 is not magnetic, less force is required to remove the magnet 2. As an example, the stage 3 corresponds to the stage 3 described in Patent Document 1, or more specifically, to a container that does not have crystallinity. It is preferable that the stage 3 is made of the outer surface of the bottom of the container. In this case, to prevent the container from becoming dirty, an anti-soiling sheet may be provided on the container as part of the configuration of the stage 3, and the container and the anti-soiling sheet may be sandwiched between them, and the sample may be magnetically oriented by a magnet.

There are no limitations on the material or shape of the magnet 2, so long as it is capable of magnetically orienting the sample across the stage 3. For example, a cylindrical shape can be used as the shape. If it is cylindrical, a circular area (e.g., 10 to 15 mm in diameter) on the top surface 3a of the stage 3 directly above the magnet 2 can be effectively used as the X-ray beam irradiation area. However, even if the magnet 2 is prismatic, it can be used without problems as long as the area directly above the magnet 2 can sufficiently encompass the X-ray beam irradiation area. As an example, the magnet 2 corresponds to the "magnet mass" described in Patent Document 1.

During irradiation with the X-ray beam, it is preferable that the magnet 2 is fixed to the inner surface of the bottom of the container. There are no limitations on the manner of fixing, and it may be fixed with an adhesive (glue, adhesive tape), or a structure that engages the bottom of the container and the magnet 2 may be formed on both. The magnet 2 may be fixed in a non-contact state with the inner surface of the bottom of the container, but in consideration of stably orienting the sample in magnetic orientation, it is preferable to have the two in contact.

It is preferable to remove the magnet 2 after the irradiation of the X-ray beam is completed, i.e., after the measurement is completed. In other words, it is preferable that the magnet 2 be detachable from the inner surface of the bottom of the container. By removing the magnet 2 after the measurement is completed, the force that draws the sample closer to the magnet 2 is released, and the sample can be easily removed from the stage portion 3.

There are no limitations on the material or shape of the sample placement correction unit 4, so long as it has an opening 4h and is positioned so that the side of the opening 4h fits within the upper region of the magnet 2. However, considering the possibility that the sample may be oriented by the sample placement correction unit 4 rather than the magnet 2, it is possible to use a non-magnetic material for the sample placement correction unit 4 (such as stainless steel or plastic (resin)).

The sample placement correction unit 4 is preferably fixed to the outer surface of the bottom of the container, i.e., the upper surface 3a of the stage unit 3, during irradiation with the X-ray beam. There are no limitations on the manner of fixing, and double-sided tape or adhesive may be used. After the irradiation of the X-ray beam is completed, i.e., after the measurement is completed, the sample placement correction unit 4 may be removed from the stage unit 3 in the same manner as the magnet 2, or may remain fixed in place.

The upper region of magnet 2 refers to the entire area directly above magnet 2, which is the area that falls within the outline of magnet 2 when viewed in a plan view.

As its name suggests, the sample position correction unit 4 corrects the position of the sample so that it is within the opening 4h and therefore within the area directly above the magnet 2. The side of the opening 4h can prevent the particles that make up the sample from scattering. In other words, the sample is only placed within the limited area of the opening 4h. In addition, even if the particles try to scatter in this state, the particles that make up the sample will eventually come into contact with the side of the opening, and the sample position is corrected to the particle orientation at the center of the magnet in a planar view (upright in this case) or a posture close to that. As a result, the sample can be held tightly while maintaining the orientation of the sample in a specific direction (up and down in this embodiment) compared to the conventional method.

As for the opening 4h of the sample placement correction unit 4, the sample placement correction unit 4 is placed on the upper surface 3a of the stage unit 3 so that when viewed in a plan view through the sample holder with the outline remaining, the outline of the opening 4h is contained within the outline of the magnet 2 fixed to the lower surface 3b of the stage unit 3.

The term "encompassing" here also includes the case where the two contours coincide (Example 1 below). However, it is preferable to enclose the contour of the opening 4h so that the two contours are only partially in contact, since this can eliminate part of the outermost edge of the magnet, which increases the inclination of the attitude of the particles that make up the sample, in the area where the sample is placed. Furthermore, it is preferable to enclose the contour of the opening 4h so that it does not come into contact with the contour of the magnet 2, since this can completely eliminate the outermost edge of the magnet in the area where the sample is placed.

As an example of this inclusion, the outline of the opening 4h of the sample placement correction section 4 may be located within a range of 0 to 2.0 mm from the outermost edge of the magnet toward the center in a plan view.

There are no limitations on the shape or size of the opening 4h of the sample placement correction unit 4. If the shape of the opening 4h is circular in a plan view, the X-ray beam irradiation area can be efficiently contained within the opening 4h. However, as long as the X-ray beam irradiation area can be contained within the opening 4h, the shape of the opening 4h in a plan view may be rectangular or the like. In this case, it is preferable to contain the X-ray beam irradiation area within the opening 4h so that the outline of the opening 4h in a plan view does not come into contact with the X-ray beam irradiation area.

In plan view, it is preferable that the opening 4h, the magnet 2, and the X-ray beam irradiation area are arranged concentrically. However, they do not need to be completely concentric, and a misalignment of about 0.2 mm is acceptable.

It is preferable that the shapes of the upper and lower sides of the opening 4h are the same, but differences are permitted to the extent that they fit within the upper region of the magnet 2.

The upper surface 4a of the sample placement correction unit 4 surrounding the opening 4h must be at the same height (so-called flush). This makes it possible to carry out a smoothing process in which particles protruding from the opening 4h of the sample placement correction unit 4 are smoothed to the upper surface 4a of the sample placement correction unit 4. Furthermore, the X-ray irradiation height is adjusted to match the upper surface 4a of the sample placement correction unit 4, making it possible to measure the angular position accurately.

Figure 3 is a schematic cross-sectional view of the sample holder 1 of this embodiment after the sample placement process and the leveling process have been carried out in sequence.

Figure 4 is a schematic plan view of the sample holder 1 of this embodiment after the sample placement process and the smoothing process have been carried out in sequence.

Figure 5(a) is a schematic cross-sectional view showing the state before the smoothing process, and Figure 5(b) is a schematic cross-sectional view showing the state after the smoothing process.

As a result of the smoothing process, the height of the measurement surface becomes constant, and the peak position (diffraction angle) of the X-ray diffraction pattern does not shift. Furthermore, as shown in FIG. 5(a) to FIG. 5(b), smoothing the particles protruding from the opening 4h allows the protruding particles to be contained within the opening 4h (i.e., the area surrounded by the side of the opening 4h and the upper surface 4a of the sample placement correction unit 4), and the sample in the opening 4h becomes even denser. To ensure these effects, it is preferable that the depth of the opening 4h of the sample placement correction unit 4 is smaller than the maximum vertical length of the particle aggregate 5a in which multiple particles constituting the sample are connected vertically due to magnetic orientation. The depth of the opening 4h may be 1.0 to 3.0 mm, and preferably 1.5 to 2.0 mm.

The sample placement correction unit 4 is preferably ring-shaped and is arranged above the magnet 2 with the stage unit 3 in between. If this configuration is adopted, this embodiment can be realized by simply placing a ring-shaped sample placement correction unit 4 (ring) on the stage unit 3 for the existing sample holder 1 described in Patent Document 1. Furthermore, when the sample placement correction unit 4 (ring) is adopted, the upper surface 4a of the ring-shaped frame can be used as an index for adjusting the sample height, which is the measurement surface, during the above-mentioned leveling process.

When the sample placement correction unit 4 is a ring, there is no limitation on the diameter of the outermost edge, and it may be larger or smaller than the outer diameter of the magnet in a plan view. In addition, there is no limitation on the shape of the outermost edge of the ring, and it may be circular, rectangular, or another shape in a plan view. In addition, there is no limitation on the shape or size of the opening 4h of the ring, as described above for the opening 4h of the sample placement correction unit 4.

The specific work content of the smoothing process may be to make the upper surface 4a of the sample placement correction section 4 flush (dashed line in Fig. 5(a)) and repeat the process of smoothing to match this upper surface 4a (Fig. 5(a) → (b)).

The method for measuring magnetic orientation using the sample holder 1 of this embodiment is as follows.

Figure 6 is a schematic perspective view showing the state in which the container of the sample holder 1 of this embodiment is installed on the base portion 6.

The container of the sample holder 1 is placed on the base 6. The placement must be such that the center of the X-ray irradiation section is at the center of the upper surface of the sample. The base 6 may be part of the X-ray diffraction measurement device.

a sample placement step of sprinkling a sample on the sample holder 1 of this embodiment and magnetically orienting the sample on the upper surface 3 a of the stage portion 3 and within the opening 4 h of the sample placement correction portion 4;
a measuring step of performing X-ray diffraction measurement on the magnetically oriented sample and calculating the degree of magnetic orientation;
has.
Preferably, the method further includes, between the sample placement step and the measurement step, a leveling step of leveling the particles protruding from the opening 4h of the sample placement correction unit 4 to fit the upper surface 4a of the sample placement correction unit 4.

The magnetic orientation measurement method using the sample holder 1 of this embodiment allows the magnetic orientation of magnetic material powder to be evaluated with high precision and reproducibility using X-ray diffraction.

The technical scope of the present invention is not limited to this embodiment, but includes various modifications and improvements within the scope of the specific effects that can be obtained by the constituent elements of the invention and their combinations.

Figure 7 is a schematic cross-sectional view of a modified sample holder after the sample placement process and smoothing process have been carried out in sequence.

In this embodiment, the sample placement correction unit 4 is a ring, but as shown in FIG. 7, a recess may be formed in the upper surface 3a of the stage unit 3 as the opening 4h of the sample placement correction unit 4, and a sample may be placed in this recess. That is, the opening 4h of the sample placement correction unit 4 may be formed by the upper surface 3a of the stage unit 3. A magnet 2 may then be placed on the lower surface 3b of the stage unit 3 in this recess, sandwiching the recessed portion of the stage unit 3, and the magnet 2 may magnetically orient the sample. That is, the opening 4h in this specification includes both through holes and non-through holes.

FIG. 8A is a schematic cross-sectional view of a modified sample holder provided with a magnet holding portion 7 after a sample placement step and a leveling step have been carried out in that order.
FIG. 8(b) is a schematic bottom view of a modified sample holder provided with a magnet holding portion 7.
The white arrows in FIG. 8 indicate the directions in which the magnet 2 is inserted and removed.

As shown in FIG. 8, as another example of a manner in which the magnet 2 is fixed to the inner surface of the bottom of the container, a magnet holder 7 may be provided on the inner surface of the bottom of the container.

In the modification shown in Fig. 8, a magnet holder 7 is provided so as to protrude downward from the inner surface of the bottom of the container. The magnet holder 7 may be separately attached to the inner surface of the bottom of the container. If the container is made of resin, the magnet holder 7 may be integrally molded with the container.
The magnet holder 7 has an opening in the horizontal direction. By inserting the magnet 2 horizontally into the magnet holder 7 from the opening 71, the magnet 2 can be positioned on the inner surface of the bottom of the container.

The present invention will be explained in detail below using examples, but the present invention is not limited to the following examples.

[Example 1]
A powder sample A having magnetic properties was placed in the sample holder 1. The amount of powder sample A was 1 g. In the sample holder 1 of Example 1, the sample placement correction part 4 was a stainless steel ring. The inner diameter of the ring was 18 mm, the outer diameter was 30 mm, the width of the ring was 6 mm, and the height (thickness) of the ring was 1.5 mm. The magnet 2 was cylindrical with a height of 15 mm. The diameter of the cylinder of the magnet 2 was 20 mm, which was set larger than the inner diameter of the ring. Then, the magnet 2 and the ring were placed concentrically. After the smoothing process, an X-ray diffraction measurement result reflecting the magnetic orientation was obtained by an X-ray diffraction measurement device.

[Comparative Example 1]
The sample holder 1 of this embodiment was not used, and a sample was placed on a simple glass sample holder 1 (without the magnet 2). Then, the X-ray diffraction measurement results were obtained in the same manner as in Example 1.

[Comparative Example 2]
The sample holder 1 of this embodiment was used without the sample position correction unit 4 (i.e., the one described in Patent Document 1). Then, the X-ray diffraction measurement results were obtained in the same manner as in Example 1.

[result]
FIG. 9 is a graph showing the results of X-ray diffraction measurement for Example 1 and Comparative Example 1 (without using magnet 2).

Looking at Figure 9, it was confirmed that there was no deviation in the 2θ direction between the diffraction peak positions of the X-ray diffraction measurement results of Comparative Example 1 and Example 1. The reason for this is that in Example 1, the sample placement correction section 4 (ring) was present, which reduced the variation in the particles that make up powder sample A. In addition, the leveling process was performed, which allowed for sufficient adjustment of the height alignment of the sample surface.

From the measurement results in Figure 9 for Example 1 and Comparative Example 1, the degree of orientation was calculated using eight arbitrary diffraction peaks (Figure 11).

Here, the degree of orientation was calculated as follows:

If the magnetic orientation degree of an arbitrary peak is K, the peak intensity of the arbitrary peak in an actual sample is IPO (actual sample), the sum of the peak intensities of all selected peaks in the actual samples is IPS (actual sample), the peak intensity of an arbitrary peak in a non-oriented state is IPO (non-oriented), and the sum of the peak intensities of all selected peaks in a non-oriented state is IPS (non-oriented), then the magnetic orientation degree K can be obtained by the following formula.
K={IPO (actual sample)/IPS (actual sample)}/{IPO (non-oriented)/IPS (non-oriented)}

In the case of Comparative Example 1, no magnetic orientation was confirmed. On the other hand, in the case of Example 1, X-ray diffraction measurement was possible in a state where powder sample A was magnetically oriented in a specific direction (C-axis direction). Also, in the case of Example 1, the K value at the (006) peak was calculated to be high, clearly indicating C-axis orientation (Figure 11).

Figure 10 is a graph showing the results of X-ray diffraction measurements for Example 1 and Comparative Example 2 (without using the sample placement correction unit 4 (ring)). Note that the graph for Example 1 in Figure 10 is the same as the graph for Example 1 in Figure 9.

From the measurement results in FIG. 10 for Example 1 and Comparative Example 2, the degree of orientation was calculated using eight arbitrary diffraction peaks (FIG. 12).

There was a difference in the 2θ direction between the diffraction peak positions in the X-ray diffraction measurement results of Comparative Example 2 and Example 1. This is because the particles constituting Powder Sample A in Comparative Example 2 were variable.

The K value at the (006) peak was calculated to be higher in Example 1 than in Comparative Example 2. This is because the powder sample A in opening 4h in Example 1 was aligned in a more uniform direction, allowing the magnetic orientation to be measured correctly (Figure 12).

1 Sample holder 2 Magnet 3 Stage (container)
3a (stage part) upper surface 3b (stage part) lower surface 4 (sample arrangement correction part (ring)
4a Upper surface (of the sample arrangement correction part) 5 Sample 5a Particle aggregate in which a plurality of particles are vertically connected due to magnetic orientation 6 Base part 7 Magnet holding part 71 Opening (of the magnet holding part)

Claims (4)

A sample holder for holding a sample when measuring the magnetic orientation of the sample by X-ray diffraction, comprising:
a stage portion on whose upper surface a sample is placed;
A magnet disposed on the underside of the stage portion;
a sample placement correction unit having an opening and arranged so that a side surface of the opening fits within the upper region of the magnet;
In a plan view, the contour of the magnet encompasses the contour of the opening so as not to come into contact with the contour of the magnet;
In a plan view, the outline of the opening of the sample arrangement correction unit is disposed within a range of 0 to 2.0 mm from the outermost edge of the magnet toward the center,
The opening depth of the sample arrangement correction unit is smaller than the maximum vertical length of a particle aggregate in a state in which a plurality of particles constituting the sample are vertically connected due to magnetic orientation associated with the arrangement of the magnets,
The upper surface of the sample placement correction portion surrounding the opening is flush with the same height.
Sample holder for magnetic orientation measurements. the stage portion being formed by the outer surface of the bottom of the container;
The magnet is fixed to the inner surface of the bottom of the container;
2. The sample holder for magnetic orientation measurement according to claim 1 , wherein the sample position correction unit is ring-shaped and is disposed above the magnet with the stage unit therebetween. a sample placement step of sprinkling a sample on the sample holder according to claim 1 or 2 to magnetically orient the sample on the upper surface of the stage portion and within the opening of the sample placement correction portion;
and a measuring step of performing X-ray diffraction measurement on the magnetically oriented sample to calculate the degree of magnetic orientation. The opening depth of the sample arrangement correction unit is smaller than the maximum vertical length of a particle aggregate in a state in which a plurality of particles constituting the sample are vertically connected due to magnetic orientation,
4. The method for measuring magnetic orientation according to claim 3 , further comprising a smoothing step between the sample placement step and the measurement step, of smoothing particles protruding from the opening of the sample placement correction unit to an upper surface of the sample placement correction unit.