JP2790247B2 - Crystal structure model - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal structure model,
In particular, the present invention relates to a novel model structure capable of easily and intuitively understanding various types of crystal structures and capable of flexibly responding to changes in crystal structures.

[0002]

2. Description of the Related Art The crystal structure of a substance is diverse, and it is often difficult to understand a complicated crystal structure only by using drawings. In such a case, the crystal structure is changed to 3
Various crystal structure models have been produced so that they can be grasped three-dimensionally. Conventional crystal structure models include an atomic position model expressing an atomic position in a unit cell and a polyhedral model expressing a geometric arrangement of a coordination polyhedron of negative ions surrounding positive ions. These are often manufactured by plastic molding, and in the former, they are composed of parts showing atoms and parts for connection connecting the atoms, and the latter has an integrally molded polyhedral structure.
Usually, the former suitable for mathematical treatment is often used, but in order to intuitively and systematically understand the crystal structure,
The latter is suitable.

[0003]

However, these crystal structure models are required to secure required rigidity for supporting a branch-like framework in the atomic position model, and to have a solid polyhedral structure in the polyhedral model, Although each is made of plastic, it is often expensive and heavy, so it is not easily available, and it is difficult to carry, so it is not widely used. In addition, these models are configured to represent either the atomic position or the geometrical arrangement, and it is difficult to immediately understand the other. In other words, the atomic position model can accurately represent the atomic position and the distance and direction of the bonding arm, but it is extremely difficult to understand the symmetry of the crystal structure and the similarity of the crystal structure. Although it is easy to understand the symmetry and the ion arrangement, it is impossible to know the position of the atoms in the unit polyhedron and the state of the bonding arms. Furthermore, a crystal structure model usually represents only one crystal structure, and cannot represent a plurality of structures. Therefore, there is a problem in that models must be prepared for the number of crystal structures. Then, this invention solves the said problem, and the subject is to provide a cheap and lightweight crystal structure model. Another object of the present invention is to provide a crystal structure model that can easily understand both the atomic position and bonding state in a unit polyhedron and the geometrical arrangement such as macroscopic symmetry of a crystal. Still another object is to provide a crystal structure model capable of expressing a plurality of crystal structures.

[0004]

Means taken by the present invention for solving the above-mentioned problems are as follows. A common connection is made at a center point, and a plurality of planar portions arranged around the center point cross each other. Connected by a line, wherein the straight outer edges of the planar portion form a ridge, and the ridges are connected to each other to form a vertex, and the ridge is a ridge between each face of the polyhedron. And a plurality of polyhedron unit structures having a skeleton structure configured such that the vertices correspond to vertices of a polyhedron,
A connection part is provided at the vertex and / or the ridge line, and the crystal structure model is formed by bonding to each other, wherein the center point and the vertex represent a position of an atom or an ion,
The intersection line and the ridge line represent a bond distance and a bond angle between the atoms or the ions.

Here, it is preferable that the connecting portion of the polyhedral unit structure is connected to the plurality of connected polyhedral unit structures so as to be relatively rotatable.

In this case, the connecting portion has a flexible strip,
In other words, it is preferable to use a string, wire, or the like made of resin, metal, fiber, or the like.

Further, the surface of some planar portions in the polyhedral unit structure is formed so as to exhibit surface characteristics different from those of other planar portions, that is, patterns, colors, textures, surface roughness, irregularities, and the like. Is preferred. In particular, only a planar portion oriented in a predetermined direction has different surface characteristics, or spin, dipole moment, electric conductivity, thermal conductivity,
It is desirable that only the planar portions corresponding to various characteristics such as the polarization axis and the refractive index have different surface characteristics.

Further, it is preferable that the polyhedral unit structure is formed by bending a thin sheet. Especially,
It is desirable to form a polyhedral skeleton structure with origami.

It is preferable to use a regular tetrahedron, regular hexahedron or regular octahedron skeleton structure as the polyhedron unit structure.

[0010] The surface of the planar portion may be a light reflecting surface.

[0011]

According to the first aspect, the vertices of the skeleton structure, the center point and other intersections where the plurality of planar portions intersect, the ridge line of the polyhedral structure, and the intersecting lines between the planar portions are used to determine the distance between adjacent atoms or ions. In addition to being able to visually represent the positional relationship, the direction and distance of bonding, the polyhedral structure makes it possible to intuitively understand the crystal periodicity and geometrical structure of the crystal such as ion arrangement.

According to the second aspect, since each of the polyhedral unit structures is rotatably connected, a plurality of crystal structures can be represented by one model depending on the degree of freedom of connection between the unit structures.

According to the fourth aspect, by forming the surface of a part of the planar portion so as to exhibit different surface characteristics, the crystal orientation, the type of atom or ion, and the difference in physical properties of the atom or ion can be expressed. Can be. In this case, the case where the surface characteristics of at least a part of the planar portion is changed for each polyhedral unit structure and the case where the common planar portion (for example,
A planar portion having a predetermined orientation, a planar portion indicating a predetermined coupling position, etc.) may have different surface characteristics.

According to the sixth aspect, since the skeleton structure is constituted by a thin sheet, the structure is light and flexible, the carrying is easy, and the manufacturing cost can be reduced. Here, in particular, it is possible to configure the skeleton structure by folding the origami, and in this case, it is possible to further reduce the weight and cost of the model.

According to the eighth aspect, by making the surface of the planar portion a light reflecting surface, light is reflected to reflect other structural portions (for example, a vertex, ridge line, planar portion, etc. existing in front). Since the appearance varies depending on the viewing direction, the three-dimensional effect as the crystal structure model increases, and the three-dimensional structure can be easily grasped. In particular, if all planar parts are light reflecting surfaces, the front structural part is reflected on the planar part and reflected, and each polyhedral unit structure looks as if it is a transparent skeleton, so the model 3D feeling can be further enhanced.

[0016]

Next, an embodiment of a crystal structure model according to the present invention will be described with reference to the drawings. [Embodiment 1] As shown in FIG. 1, a crystal structure model according to the present embodiment has a unit structure U having a regular octahedral skeleton structure.
8 are connected. The unit structure U8 is easily assembled by folding origami as described later, and has six vertices P and twelve ridge lines T around the center O, respectively. These vertices P and ridge lines T are formed by twelve planar portions Q arranged at an angle of 90 degrees around the center O.

The structure shown in FIG. 1 shows a rutile structure which is a crystal structure of TiO ₂ . The unit structures U8 having the octahedral skeleton structure in the figure are all the same, and the unit structure U8 (H) in which the hatched surface faces upward (Z direction) and the front (X direction) Unit structure facing U8
(S) is connected between vertices or between ridge lines.
The unit structures U8 (H) and the unit structures U8 (S) are connected by ridge lines, respectively, and the unit structures U8 (H) and U8 (S) are connected by a vertex P. In this figure, three unit structures U8 are arranged in each of the X, Y, and Z directions, and a total of 23 unit structures U8 are integrally connected.

FIG. 3 shows the manufacturing method and structure of the unit structure U8. As shown in FIG. 3 (a), a square origami 4 is folded at a mountain fold line 4a and a valley fold line 4b, so that a vertex P
Then, the one provided with the four side pieces S is formed. This is 6
A set is prepared and assembled by interlocking with each other such that each vertex P forms each vertex of the regular octahedron. As shown in FIG. 3B, the unit structure U8 has vertices Pa, Pb, and 6 of six sets of origami pieces a, b, c, d, e, and f.
Pc, Pd, Pe, and Pf form the vertices of the upper end, the rear end, the right end, the lower end, the front end, and the left end, respectively. One of the side pieces is housed inside, and the other pair is assembled to house the side pieces of another origami piece. By assembling in this manner, the side pieces S of the respective origami pieces are in a state of being overlapped with each other, and 12 planar portions Q having a skeleton structure are formed.

In this crystal structure model, as shown in FIG. 4, a connection portion J between ridge lines T of adjacent unit structures U8 is formed.
1 is directly attached by an adhesive 2. In addition, the connection portion J2 between the vertexes P of the adjacent unit structure U8 is inserted into the unit structure U8 by making a hole in the vertex P, and is connected to the unit structure U8 via the string 3 fixed with an adhesive or the like. It is connected. The string 3 of the connecting portion J2 is composed of two unit structures U to be connected.
8 can be arranged at an arbitrary angle with respect to each other, and it is also allowed to rotate each other around the axis of the cord 3.

In the unit structure U8, the atomic position can be indicated by the center O and the vertex P, and the periodicity of the crystal structure can be intuitively indicated by the skeleton structure as in the case of the polyhedral model. The arrangement of ions and negative ions can be immediately understood from the positions of the center O and the vertex P.

Next, a typical example of this embodiment will be described with reference to FIGS. The crystal model shown in FIG. 1 shows a rutile structure as described above. For example, TiO ₂ , F
It has a crystal structure belonging to a tetragonal system such as eF ₂ and NiF ₂ . In each unit structure U8, Ti,
Positive ions such as Fe and Ni are located, and O,
Negative ions such as F are located.

When the angle of each layer is changed as shown by an arrow F1 in FIG. 2A with respect to the crystal model of the rutile structure, a marcasite structure is formed. For example, an orthorhombic crystal such as FeS _{2 is formed.} It becomes a crystal structure belonging to the system. Also in this case, a positive ion such as Fe is located at the position of the center O, and a negative ion such as S is located at the vertex P.

Further, as shown in FIG. 2B, when the angle of each layer was further changed as shown by an arrow F2 with respect to this marcasite structure, the layer was present on the X direction side of the unit structure U8 (S). The vertex P contacts the vertex P near the X direction of the upper unit structure U8 (H). In this state, a cubic close-packed (face-centered cubic lattice) structure is obtained.

As described above, in the present embodiment, since the degree of freedom of the string 3 connecting each vertex is high, one crystal model can express three crystal structures. 7 to 10 show photographed shapes of crystal models representing the above three crystal structures. 7 and 8 show a state in which the rutile structure is photographed from different crystal directions, respectively, and FIG. 9 shows a marcasite structure. FIG. 10 shows a cubic close-packed structure.

FIGS. 11 and 12 show the spinel structure viewed from different directions. According to this model, the structural similarity between different crystals can be intuitively understood. For example, (1) of the face-centered cubic lattice shown in FIG.
By comparing the shape in the 10) direction with the shape of the spinel in the (110) direction shown in FIG. 12B, the structural similarity between the two can be visually grasped. Structurally, metal atoms located at the center of the octahedron escape from the face-centered cubic lattice to form a spinel structure. The spinel structure can be understood as a structure in which lattice defects occur in the face-centered cubic lattice.

FIG. 13 shows a pyrochlore structure. In this crystal model, the octahedral unit structure U8 is connected at a certain inclination angle, and is suitable for understanding that the bonding direction and the bonding distance of the unit polyhedron affect various physical properties. For example, it is known that a magnetic interaction (super-exchange interaction) that mediates a negative ion exists between magnetic positive ions at the center of an octahedron. When looking at the directions of the two magnetic positive ions, the fact that the magnetic properties change depending on the angle between the two directions can be considered in comparison with actual measurement results.

In the crystal model of this embodiment, FIGS.
As shown by the diagonal lines in the figure, the anisotropy of physical properties such as electronic and electrical properties, magnetic properties, and optical properties of the crystal is expressed by coloring the planar parts existing in a common plane for each layer in the same color. It is also possible. When the shaded surface in the drawing is colored, the color of the crystal model viewed from the X direction and the Z direction in FIG. 1 showing the rutile structure is alternately different for each layer. This change in color corresponds to the direction of the magnetic spin. That is, in each layer in which only the unit structures U8 (H) or U8 (S) are arranged in one line, all the unit structures U8 appear to have the same color. This is because the spin directions of the central positive ions are aligned in the layers. It corresponds to. On the other hand, adjacent layers look different colors, which corresponds to the fact that the spin direction of the central positive ion is opposite to each other between adjacent layers. Such a correspondence can be applied to electrical characteristics such as electric conductivity and dielectric constant in a predetermined direction of the crystal, and optical characteristics such as refractive index and polarization.

As described above, in this embodiment, the position of the atom or ion in the crystal is directly known from the center and each vertex, and the length and angle of the bonding arm are directly known from each ridge or an intersection line between a plurality of planes. In addition, by tracing the surface of the polyhedral structure (the regular octahedron in the above embodiment), the geometrical structure such as the periodicity of the crystal structure and the ion arrangement can be intuitively understood. In particular, FIGS. 1 and 2
The different crystal structures can be represented by one model as shown in (1), and the similarity and structural relationship between the crystals can be easily understood. Further, by processing a plurality of planar portions into different patterns, colors, materials, surface roughness, and the like, information related to the characteristics of the crystal structure can be expressed.

Further, since this embodiment is made of origami and a string, it has a very flexible structure, and can freely move the connecting portion as shown in FIGS. 1 and 2, and is extremely lightweight. It is easy to carry. Even when such advantages are regarded as important, the sheet may be made of a sheet-like material such as a thin resin plate or a metal plate, instead of being made of paper as in the above embodiment.

Second Embodiment Next, a second embodiment according to the present invention.
Will be described. FIG. 5 shows a unit structure U4 having a regular tetrahedral skeleton structure different from the regular octahedral skeleton structure used in the above embodiment. FIG. 5A shows how to fold a regular tetrahedral unit structure U4 using origami paper. By folding the origami 5 having the ratio of the length and width of 1: 1: root 2 to form origami pieces k, and combining these six sets, a unit structure U4 of a regular tetrahedron (skeleton) shown in FIG. 5B is completed. . This unit structure U4 is
It has four vertices Pg, Ph, Pi, and Pj, and six ridge lines respectively formed on six planar portions Q corresponding to six origami pieces k1, k2, k3, k4, k5, and k6. The six planar portions Q are arranged around the center O at equal angles to each other. The method of fabricating a regular tetrahedron skeleton using this origami is described in "Origami-All about Dream Weaving Geometry-" (published in 1988, Nikko Publishing / Author: Kunihara Kasahara).

Also in this unit structure U4, similarly to the above-mentioned unit structure U8, it is possible to connect various unit structures at each vertex and each ridge line to express various crystal structures. As an example of a crystal structure using this unit structure U4,
FIG. 6 shows a crystal model of a fluorite structure represented by CaF ₂ . This model is configured by connecting the ridge lines T of the eight unit structures U4 to each other. 14 and 15 show an example of manufacturing the fluorite structure shown in FIG. Here, the left models shown in FIGS. 14A and 14B are formed by combining regular tetrahedral unit structures that are not skeleton structures. FIG. 14 (a)
In the crystal model of the skeleton structure on the right side shown in (b), the position of the atom (ion) at the center position of the polyhedron can be shown, and the bonding direction and the bonding distance between the atoms are obvious at a glance. On the other hand, in the model on the left side, although the symmetry of the crystal can be understood, the arrangement and bonding relationship of the central atom (ion) cannot be seen. FIG.
(B) shows a state where the model shown in FIG. 6 is divided into two parts each including four unit structures U4. In such a state of being divided into two, all the structures hidden inside can be expressed. Therefore, it is preferable that connection parts necessary for dividing into two parts (in this case, four sets of ridge line connection parts) are configured to be detachable.

[Production Example] Using the embodiment described above,
Manufacturing examples of other various crystal structures will be described below with reference to the drawings. However, depending on the crystal structure, some of the positive ions are omitted, and only the basic structure composed of regular tetrahedral, regular hexahedral, and regular octahedral skeletons is shown.

FIG. 16 shows a basic structural unit (a) composed of five tetrahedrons of tetragonal tungsten bronze and a crystal structure (b) of tetragonal tungsten bronze. Although it is not clear from the usual notation of the crystal structure using a unit cell, according to this crystal model, it can be understood that this crystal structure is assembled from five basic octahedral basic structural units. In order to assemble this crystal structure from the basic structural unit consisting of five regular octahedrons, the size of the skeleton of the regular octahedron at the center of the basic structural unit is larger than the size of the skeleton of the four surrounding regular octahedrons. Can also be understood that it must be small.

FIG. 17 shows a basic structural unit (a) composed of five regular octahedrons of hexagonal tungsten bronze and a crystal structure (b) of tetragonal tungsten bronze. It can be seen that this crystal structure is assembled from the basic structural unit consisting of the five regular octahedrons shown in FIG. It can also be understood that this crystal structure has similarities to the pyrochlore structure shown in FIG. 13 and the tetragonal tungsten bronze structure shown in FIG.

FIGS. 18 and 19 show a perovskite structure and YBCO (YBa ₂ Cu) which is an oxide high-temperature superconductor.
The crystal structure of ₃ O ₇ ) is shown in comparison. The perovskite structure is represented by a model connecting the vertices P of the unit structure U8. The connection in the extension direction between the unit structures U8 in both structures is made continuously by passing one strip (string) through the center of each unit structure U8. Of course, it can also be performed with an adhesive or a short strip similar to the string 3 shown in FIG.
From this model, it can be understood that the crystal structure of YBCO is based on a perovskite structure, and is completed due to lattice defects of oxygen ions. In addition, the surface containing copper ions is shown by changing the color of the planar portion so that the direction of the surface where superconducting current is considered to flow and the anisotropy of electric conduction can be understood.

FIG. 20 shows a corundum structure. This crystal structure belongs to a hexagonal system and can be understood as a crystal structure generated by lattice defects of positive ions based on a hexagonal close-packed structure. This model glues three ridges arranged in a regular triangle to three similar ridges of an adjacent unit structure U8 by sharing two of the three vertices of the unit structure U8. It is constituted by. This model is also constructed on the basis of a skeleton of two regular octahedrons sharing a face (a pair of unit structures U8 facing in the same direction and having one ridge line bonded to each other). If two different kinds of positive ions are arranged at the center of the face, an ilmenite structure (TiFeO ₃ )
Becomes

FIG. 21 (a) shows that 8 is expanded and contracted in one axis direction.
The unit structure of a face is shown. An octahedral unit structure that expands and contracts in a uniaxial direction is suitable for expressing a lattice distorted by the Jahn-Teller effect. Further, these modified unit structures can also be used when different negative ions are coordinated like boracite.

FIG. 21B shows a unit structure of a regular octahedron made by using silver paper. When a regular polyhedron is formed using silver paper, a part of the skeleton structure existing in front is reflected on the planar portion due to reflection of light on the planar portion, so that the polyhedral skeleton looks as if it is transparent. Therefore,
This can be used to enhance the stereoscopic effect of the crystal model. Also, if the unit structure is manufactured by mixing silver paper and colored paper, the planar part made of colored paper will be reflected on the planar part of silver paper,
It seems that the color of the polyhedron skeleton changes depending on the viewing angle (crystal direction). These features make it easier to spatially grasp the crystal structure, and are therefore more preferable as a crystal structure model for expressing a solid.

As described above, in the present invention, various crystal structures are formed by combining unit structures each composed of a polyhedral skeleton structure. In the above embodiment, a model using a regular octahedral skeleton suitable for mainly showing an ion-bonding crystal and a model using a tetrahedral skeleton suitable for mainly showing a covalent bonding crystal have been mainly described. However, the polyhedron unit structure does not necessarily have to be a regular polyhedron, and as shown in FIG. 20, it is apparent that the same expression can be obtained by using a modified polyhedron skeleton structure. In addition, for other polyhedral structures,
It can be represented by a combination of a tetrahedral skeleton or a regular tetrahedral skeleton. Furthermore, it is also possible to use a unit structure having a number of faces other than these. For example, a body-centered cubic lattice can be represented by a unit structure having a regular hexahedron skeleton structure. In general, the skeleton structure referred to herein is a structure in which a plurality of planar bodies sharing the center O are arranged around the center O at predetermined mutual angles (all of which are not necessarily equal to each other). It is.

Each of the polyhedral unit structures U8 and U4 having the skeleton structure in the above embodiment is composed of a plurality of origami pieces each having a side piece formed by origami such that each side piece forms a planar portion of the skeleton structure. Each is manufactured by combining. However, the crystal structure model according to the present invention may be configured by, for example, forming a thin plate made of a synthetic resin into the shape of the planar portion and fitting these thin plates together. In this case, the connecting portion connecting between the unit structures U8 and U4 is a screw or a hook attached to the apex.
It is also possible to use an engaging member such as a fastener formed on the ridge line, a pair of a fitting rib and a fitting groove. In this case, since the connection portion is configured to be detachable, the connection relationship between the unit structures can be freely changed. In particular, by configuring the planar portions of different colors to be detachable from each other, a model can be assembled by freely selecting combinations of the color configurations of the planar portions.

[0041]

As described above, according to the present invention,
The skeleton structure allows visual representation of the positions of atoms or ions, bonding directions and distances, and allows intuitive understanding of crystal geometric structures such as crystal periodicity and ion arrangement. Further, it has a remarkable effect that a plurality of crystal structures can be represented by one model depending on the degree of freedom of connection between the unit structures, and a lightweight and flexible structure can be obtained. is there.

[Brief description of the drawings]

FIG. 1 is a perspective view showing Example 1 of a crystal structure model according to the present invention.

FIG. 2A is a perspective view showing a state in which a part of the first embodiment is deformed, and FIG. 2B is a perspective view showing a state in which a part of the first embodiment is further deformed.

FIGS. 3A and 3B are an explanatory view illustrating a method of manufacturing a polyhedral unit structure used in the first embodiment and a perspective view illustrating a polyhedral unit structure in the first embodiment; FIGS.

FIG. 4 is an enlarged perspective view showing a connection state of a connection portion between the polyhedral unit structures in the first embodiment.

FIGS. 5A and 5B are an explanatory view showing a method of manufacturing a polyhedral unit structure used in a second embodiment of the crystal structure model according to the present invention, and a perspective view showing a polyhedral unit structure in the second embodiment; FIGS.

FIG. 6 is a perspective view showing a crystal structure model of Example 2.

FIGS. 7A and 7B are photographs (a) and (b) in place of perspective views of the product structure model showing the rutile structure of Example 1 viewed from different plane directions.

FIG. 8 is a photograph replacing a perspective view of the product structure model showing the rutile structure of Example 1 viewed from another surface direction.

FIG. 9 is a photograph replacing a perspective view of a crystal structure model showing a marcasite structure that can be expressed by modifying Example 1.

FIG. 10 is a photograph replacing a perspective view showing a crystal structure model obtained by transforming Example 1 into a face-centered cubic lattice.

FIGS. 11A and 11B are photographs (a) and (b) each of which is a perspective view in which a product structure model showing a spinel structure is viewed from different directions.
It is.

FIGS. 12A and 12B are photographs (a) and (b) of perspective views of the product structure model showing the spinel structure viewed from different directions.

FIGS. 13A and 13B are photographs (a) and (b) in place of perspective views of a crystal structure model showing a pyrochlore structure viewed from different directions.

FIGS. 14A and 14B are photographs (a) and (b) in which a crystal structure model (Example 2) showing a fluorite structure is replaced with a perspective view in which the polyhedral structure model similar to the conventional example is viewed from different directions.

FIG. 15 is a photograph (a) replacing a perspective view of a crystal structure model (Example 2) showing a fluorite structure viewed from another direction, and a photograph (b) replacing a perspective view showing a state where the model is divided into two parts. ).

FIGS. 16A and 16B are a photograph (a) replacing a plan view showing a basic structure cluster of a tetragonal tungsten bronze structure and a photograph (b) replacing a plan view of a crystal structure model showing a tetragonal tungsten bronze structure.

FIGS. 17A and 17B are a photograph (a) replacing a plan view showing a basic structural cluster of a hexagonal tungsten bronze structure and a photograph (b) replacing a plan view of a crystal structure model showing a hexagonal tungsten bronze structure.

FIGS. 18A and 18B are a photograph (a) replacing a perspective view showing a crystal structure model of a bebroskite structure and a photograph (b) replacing a perspective view showing a crystal structure model of a YBCO structure.

FIG. 19 shows a crystal structure model of a peproskite structure and YB
It is a photograph (a) and (b) which substitute a perspective view which looked at a crystal structure model of a CO structure from a different direction, respectively.

FIG. 20 is a photograph replacing a perspective view of a crystal structure model showing a corundum structure.

FIGS. 21A and 21B are photographs in place of a perspective view showing a shape example of a unit structure of a regular octahedral skeleton expanded and contracted in a uniaxial direction, and photographs in place of a perspective view showing a unit structure of a regular octahedral skeleton manufactured using silver paper; (B).

[Explanation of symbols]

2 Adhesive 3 String (strip) 4,5 Origami (thin sheet) U8 (has regular octahedral skeleton structure) Polyhedral unit structure U4 (has regular tetrahedral skeleton structure) Polyhedral unit structure J1, J2 Connection O Center P Vertex Q Planar part T Edge

Claims (8)

(57) [Claims] A common connection at a center point, said center
Multiple planar parts arranged around a point intersect each other
Connected, the straight outer edge of the planar portion forms a ridge line,
The ridge lines are configured to connect with each other to form a vertex.
And the ridge line corresponds to the ridge line between each face of the polyhedron,
A crystal formed by connecting a plurality of polyhedral unit structures having a skeleton structure in which the vertexes correspond to the vertices of a polyhedron with connecting portions at the vertices and / or the ridge lines and connecting them together In a structural model, the center point and the apex indicate positions of atoms or ions.
Express, the intersection line and the ridge line are between the atoms or
A crystal structure model expressing a bond distance and a bond angle between the ions . 2. The crystal structure model according to claim 1, wherein the connecting portion of the polyhedral unit structure connects the plurality of connected polyhedral unit structures so as to be relatively rotatable. 3. The crystal structure model according to claim 2, wherein the connecting portion is formed of a flexible strip. 4. A crystal structure model according to claim 1, wherein a part of said planar portion in said polyhedral unit structure is formed so as to exhibit surface characteristics different from those of other planar portions. . 5. The crystal structure model according to claim 4, wherein the surface characteristic is a color. 6. The crystal structure model according to claim 1, wherein the polyhedral unit structure is formed by bending a thin sheet. 7. The crystal structure model according to claim 1, wherein the polyhedral unit structure has a regular tetrahedron, regular hexahedron or regular octahedron skeleton structure. 8. The crystal structure model according to claim 1, wherein the surface of the planar portion is a light reflecting surface.