Three-dimensional orientation method of ferroelectric crystal based on optical characteristics
By combining the optical properties of ferroelectric crystals and X-ray diffraction patterns with polarizing microscopy, the problem of three-dimensional orientation of single crystals without natural growth surfaces has been solved, realizing an efficient and low-cost three-dimensional orientation method that avoids dependence on expensive equipment.
Patent Information
- Application Number
- CN202310582894.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-05-23
- Publication Date
- 2026-02-17
- Estimated Expiration
- 2043-05-23
AI Technical Summary
In the existing technology, there is a lack of simple methods for three-dimensional orientation of single crystals without natural growth surfaces, especially given the scarcity of Laue crystal orientation instruments, which leads to longer research cycles and increased costs.
The three-dimensional orientation of the crystal is determined by the optical properties of the ferroelectric crystal, the crystal plane index is determined by X-ray diffraction pattern, and the extinction phenomenon is observed by cross-polarized microscopy to determine the spontaneous polarization direction, thereby determining the three-dimensional orientation of the crystal.
It enables efficient and low-cost three-dimensional crystal orientation without relying on expensive Laue crystal orientation instruments, and is simple to operate with minimal loss.
Smart Images
Figure CN116593401B_ABST
Abstract
Description
Technical Field
[0001] This application relates to a three-dimensional orientation method for ferroelectric crystals based on optical properties, belonging to the field of crystal technology. Background Technology
[0002] Crystalline materials are solid materials composed of crystalline substances, whose atoms, ions, molecules, or groups exhibit periodic, regular arrangements and translational symmetry; these are known as single-crystal materials. Single-crystal materials have wide applications in cutting-edge science and technology. Crystalline materials include ferroelectric crystals, laser crystals, semiconductor crystals, scintillation crystals, electro-optic crystals, acousto-optic crystals, and magneto-optic crystals. The most prominent characteristic of crystals is anisotropy; their physical properties are also anisotropic, such as optical, electrical, and mechanical properties, all of which have directionality. Therefore, the crystal orientation must be clearly defined when using crystals, which necessitates three-dimensional orientation.
[0003] Currently, most crystals used are artificial crystals. Depending on the growth method, many artificial crystals lack natural growth faces; for example, crystals grown using the Czochralski method and the crucible-lowering method are cylindrical, which poses challenges to three-dimensional orientation. The most widely used method for orienting cylindrical crystals is the Laue orientation method. Laue crystal orienters can quickly determine the three-dimensional orientation of a crystal, but they are expensive, and many research institutions lack the necessary equipment, hindering widespread use and delaying research cycles. Another method is X-ray orientation. X-ray orientation can measure the deviation between a known crystal face and a specific crystal face, but it requires prior knowledge of the approximate crystal indices of that face and can only perform precise one-dimensional orientation of a known face, lacking three-dimensional orientation capabilities. Therefore, given the scarcity of Laue crystal orienters, a simpler method for three-dimensional crystal orientation is needed. Summary of the Invention
[0004] The purpose of this application is to achieve three-dimensional orientation of ferroelectric crystals solely through their optical characteristics, without using an expensive Laue crystal orientation instrument. Among numerous crystal materials, ferroelectric crystals are a class of crystals exhibiting spontaneous polarization. Orthogonal polarizing microscopy can be used to observe extinction phenomena in ferroelectric crystals, and the direction of spontaneous polarization can be determined through extinction rules. Furthermore, the direction of spontaneous polarization in ferroelectric crystals is closely related to their crystallographic symmetry. Therefore, the optical properties of ferroelectric crystals can be used for three-dimensional orientation.
[0005] According to one aspect of this application, a three-dimensional orientation method for ferroelectric crystals based on optical properties is provided, comprising the following steps:
[0006] 1) Cut a test wafer from the ferroelectric crystal under test;
[0007] 2) Obtain the X-ray diffraction pattern of the cut surface of the test wafer, and determine the crystal plane index (h1k1l1) represented by the strongest diffraction peak in the X-ray diffraction pattern of the test wafer;
[0008] 3) The angle between the (h1k1l1) crystal plane and the cut surface of the test wafer is obtained using an X-ray orientation instrument. The cut surface is then corrected to obtain a cut surface with a crystal plane index of (h1k1l1).
[0009] 4) Polish the (h1k1l1) crystal plane to a thickness ≤200μm, observe the extinction phenomenon of the polished wafer using an orthogonal polarizing microscope, and determine the direction of the spontaneous polarization of the polished wafer projected onto the (h1k1l1) crystal plane;
[0010] 5) Determine the intersection direction [uvw] of another crystal plane (h2k2l2) and (h1k1l1) by using spontaneous polarization in the projection direction of (h1k1l1);
[0011] 6) The three-dimensional orientation of the crystal is obtained by using the crystal plane (h1k1l1) and the intersection direction [uvw] of the two crystal planes.
[0012] Specifically, a wafer is arbitrarily cut from the crystal to be tested; the full-spectrum X-ray diffraction pattern of the wafer's cut surface is obtained and compared with the full-spectrum powder X-ray diffraction pattern of the crystal to determine the crystal plane index (h1k1l1) represented by the strongest diffraction peak in the wafer's full-spectrum X-ray diffraction pattern; the angle between the crystal plane to which the strongest diffraction peak belongs and the wafer's cut surface is determined using a conventional X-ray orientation instrument, and a wafer with the crystal plane index (h1k1l1) is cut by adjusting the cutting angle; the (h1k1l1) crystal plane index is then determined. 1) The wafer is ground and polished to a thickness of ≤200μm. The extinction phenomenon of the polished wafer is observed using an orthogonal polarizing microscope to determine the spontaneous polarization direction. The intersection direction [uvw] of the other crystal plane (h2k2l2) and (h1k1l1) is determined by the projection of the spontaneous polarization onto (h1k1l1). The three-dimensional orientation of the crystal can be determined by using the crystal plane (h1k1l1) and the intersection direction [uvw] of the two crystal planes.
[0013] In this application, the crystal plane index is represented by (hkl), and different crystal planes are represented by different subscripts.
[0014] Optionally, the ferroelectric crystal to be tested is a single crystal without a natural growth surface, that is, the crystal to be tested is a large single crystal without a natural growth surface, and the three-dimensional crystal orientation of the crystal cannot be directly determined by the natural growth surface, such as cylindrical crystals grown by the Czochralski method or the crucible lowering method.
[0015] Optionally, the ferroelectric crystal under test has spontaneous polarization.
[0016] Optionally, the device for acquiring the X-ray diffraction pattern is a powder X-ray diffractometer.
[0017] Optionally, the powder X-ray diffractometer includes a test crystal plane fixing device, an X-ray emitting device, a signal receiving device, and an angle measuring device.
[0018] Optionally, the orthogonal polarizing microscope includes a polarizer, an analyzer, and a stage;
[0019] The polarizer and the analyzer are orthogonal in structure.
[0020] The stage can rotate 360°.
[0021] Optionally, the included angle δ between the crystal planes (h2k2l2) and (h1k1l1) satisfies:
[0022] Triclinic crystal system:
[0023] Where S 11 =b 2 c 2 sin 2 α;
[0024] S 22 =a 2 c 2 sin 2 β;
[0025] S 33 =a 2 b 2 sin 2 γ;
[0026] S 12 =abc 2 (cosαcosβ-cosγ);
[0027] S 23 =a 2 bc(cosβcosγ-cosα);
[0028] S 13 =ab 2 c(cosαcosγ-cosβ);
[0029] Monoclinic system:
[0030] Orthorhombic crystal system:
[0031] Trigonal crystal system:
[0032] Tetragonal crystal system:
[0033] Hexagonal crystal system:
[0034] Cubic crystal system:
[0035] Where a, b, c, α, β, and γ are unit cell parameters, d1 and d2 are the interplanar spacings of the crystal planes (h1k1l1 and h2k2l2), and V is the unit cell volume.
[0036] Optionally, the intersection direction [uvw] of the crystal plane (h2k2l2) and the crystal plane (h1k1l1) satisfies:
[0037] u = k1l2 – l1k2;
[0038] v = l1h2 – h1l2;
[0039] w = h1k2 – k1h2.
[0040] The beneficial effects that this application can produce include:
[0041] 1) The three-dimensional orientation method provided in this application can achieve three-dimensional orientation of crystals using commonly used X-ray diffractometers, ordinary X-ray orientation instruments, and polarizing microscopes. This application does not require an expensive Laue crystal orientation instrument to meet the requirements of three-dimensional orientation.
[0042] 2) The three-dimensional orientation method provided in this application has the characteristics of simple operation, high efficiency and low crystal loss. Attached Figure Description
[0043] Figure 1 This is a flowchart of the three-dimensional orientation method for ferroelectric crystals provided in Embodiments 1 to 3 of this application;
[0044] Figure 2 The powder X-ray diffraction patterns of the crystal samples to be tested provided in Examples 1 to 3 of this application;
[0045] Figure 3 The X-ray diffraction patterns of the wafers provided in Examples 1 to 3 of this application are shown below. (a) is the X-ray diffraction pattern of an arbitrary cut surface obtained in Example 1, (b) is the X-ray diffraction pattern of the (111) plane after cut surface correction obtained in Example 1, (c) is the X-ray diffraction pattern of an arbitrary cut surface obtained in Example 2, (d) is the X-ray diffraction pattern of the (110) plane after cut surface correction obtained in Example 2, (e) is the X-ray diffraction pattern of an arbitrary cut surface obtained in Example 3, and (f) is the X-ray diffraction pattern of the (211) plane after cut surface correction obtained in Example 3.
[0046] Figure 4 These are polarizing microscope images of the (111) wafer provided in Embodiment 1 of this application, wherein (a) is a polarizing microscope image of the (111) polished wafer obtained in Embodiment 1 without an analyzer, (b) is an image of the (111) polished wafer obtained in Embodiment 1 at its initial position under an orthogonal polarizing microscope, (c) is an image of the (111) polished wafer obtained in Embodiment 1 after rotating 14° from the position in (b) under an orthogonal polarizing microscope, and (d) is an image of the (111) polished wafer obtained in Embodiment 1 after rotating 45° from the position in (c) under an orthogonal polarizing microscope;
[0047] Figure 5 The figures provided in Examples 1-3 of this application are schematic diagrams of the projection of spontaneous polarization on the crystal plane (h1k1l1) and the intersection line [uvw] of the crystal planes (h2k2l2) and (h1k1l1). Figure (a) is a schematic diagram of the spontaneous polarization direction and the (111) crystal plane of the pseudocubic phase PMN-28PT single crystal obtained in Example 1; Figure (b) is a projection of the spontaneous polarization direction on the (111) plane obtained in Example 1; Figure (c) is a schematic diagram of the intersection line direction [01_1] of the crystal planes (111) and (100) obtained in Example 1; and Figure (d) is a schematic diagram of the pseudocubic phase PMN-28P obtained in Example 2. (e) Figure is a schematic diagram of the spontaneous polarization direction of the T single crystal and the (110) crystal plane; (f) Figure is a schematic diagram of the intersection direction
[001] of the crystal planes (110) and (100) obtained in Example 2; (g) Figure is a schematic diagram of the spontaneous polarization direction of the pseudocubic phase PMN-28PT single crystal and the (211) crystal plane obtained in Example 3; (h) Figure is a projection of the spontaneous polarization direction of the T single crystal and the (211) crystal plane obtained in Example 3; (i) Figure is a schematic diagram of the intersection direction [01_1] of the crystal planes (211) and (100) obtained in Example 3.
[0048] Figure 6 The X-ray diffraction patterns of the standard (100) crystal plane cut out after the crystal has been oriented in Examples 1 to 3 of this application;
[0049] Figure 7 The images shown are polarizing microscope images of the (110) wafer provided in Embodiment 2 of this application, wherein (a) is a polarizing microscope image of the (110) polished wafer obtained in Embodiment 2 without an analyzer, (b) is an image of the (110) polished wafer obtained in Embodiment 2 at its initial position under an orthogonal polarizing microscope, (c) is an image of the (110) polished wafer obtained in Embodiment 2 after rotating 38° from the position in (b) under an orthogonal polarizing microscope, and (d) is an image of the (110) polished wafer obtained in Embodiment 2 after rotating 45° from the position in (c) under an orthogonal polarizing microscope;
[0050] Figure 8 The images shown are polarized light microscopy observations of the (211) crystal orientation wafer provided in Embodiment 3 of this application. (a) is a polarized light microscopy observation of the (211) polished wafer obtained in Embodiment 3 without an analyzer; (b) is an image of the (211) polished wafer obtained in Embodiment 3 at its initial position under an orthogonal polarizing microscope; (c) is an image of the (211) polished wafer obtained in Embodiment 3 after rotating 12° from the position in (b) under an orthogonal polarizing microscope; and (d) is an image of the (211) polished wafer obtained in Embodiment 3 after rotating 45° from the position in (c) under an orthogonal polarizing microscope. Detailed Implementation
[0051] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0052] In the embodiments of this application:
[0053] The X-ray powder diffractometer used was a Rigaku MiniFlex 600 benchtop X-ray powder diffractometer.
[0054] The X-ray orientation instrument used was the YX-2 type X-ray crystal orientation instrument from Liaodong X-ray Instrument Co., Ltd. Its sample stage range was 0–60°, and the corresponding X-ray signal receiver range was 0–120°.
[0055] The orthogonal polarizing microscope used was the Nikon LV100POL model. It was equipped with a polarizer, analyzer, and a 360° rotating stage.
[0056] Example 1:
[0057] 0.72Pb(Mg) grown by crucible descent method 1 / 3 Nb 2 / 3 O3-0.28PbTiO3 (PMN-28PT) crystals are cylindrical and lack natural crystal faces; therefore, the crystal orientation cannot be determined by the natural growth planes. The following uses... Figure 1 The steps in the crystal orientation method flowchart shown are for three-dimensional orientation of the crystal.
[0058] Step 1: Cut a wafer from the PMN-28PT crystal.
[0059] Step 2: Perform powder X-ray diffraction on the cut crystal. The resulting powder X-ray diffraction pattern is shown below. Figure 2As shown, the values were indexed. It should be noted that although PMN-28PT crystal has a trigonal crystal system, its cell parameter α is close to 90°, therefore it is also considered a pseudocubic phase. Therefore, it can be treated as a cubic crystal system during three-dimensional orientation. Simultaneously, full-spectrum X-ray diffraction was performed on the cut wafer, and the obtained X-ray diffraction pattern of the test wafer is shown below. Figure 3 As shown in (a). Through Figure 2 and Figure 3 In comparison (a), it was found that the strongest peak in the X-ray diffraction pattern of the test wafer was the diffraction peak of the (111) plane;
[0060] Step 3: Fix the test wafer from Step 2 onto the X-ray orientation instrument and use the X-ray orientation instrument to obtain the deflection angle between the test wafer's crystal plane and the standard (111) plane. After obtaining the deflection angle, correct the cut surface of the crystal to be tested to obtain the accurate cut surface of the (111) plane. Figure 3 As shown in (b).
[0061] Step 4: Grind and polish the wafer with the accurate (111) surface obtained in Step 3 to a thickness of 128μm. Place the polished wafer on the stage of a polarizing microscope to observe the extinction phenomenon of the polished wafer. Figure 4 This is an image of the polished slide (111) under a polarizing microscope, in which... Figure 4 (a) is a diagram of the (111) polished disc without an analyzer, with its bottom edge selected as the reference edge for the starting position; Figure 4 Image (b) shows the starting position of polishing disc (111) under an orthogonal polarizing microscope. Figure 4 (c) is (111) polishing sheet from Figure 4 The image in (b) is rotated 14° and viewed under an orthogonal polarizing microscope. At this point, the field of view is the darkest, indicating that the spontaneous polarization direction is consistent with the direction of the polarizer or analyzer. Figure 4 (d) is (111) polished sheet from Figure 4 The image in Figure (c) is rotated 45°. At this point, the field of view is the brightest, indicating that the angle between the spontaneous polarization direction and the polarizer or analyzer direction is 45°.
[0062] Step 5: In this embodiment, the crystal plane (h1k1l1) is the (111) plane. Figure 5 Figure (a) shows a schematic diagram of the spontaneous polarization direction and (111) crystal plane of a pseudocubic PMN-28PT single crystal. Figure 5 In diagram (b), the spontaneous polarization direction is projected onto the (111) plane. In this embodiment, the crystal plane (h2k2l2) can be selected as the (100) plane, and its intersection direction [uvw] is [01_1], as shown below. Figure 5 As shown in (c). By comparison Figure 5 (b) The projection of the spontaneous polarization direction onto the (111) plane and Figure 4The projection direction of the spontaneous polarization onto the (111) plane, as determined in the equation, can determine the direction of the intersection line [01_1] between the (111) and (100) planes, as shown below. Figure 5 As shown in (c).
[0063] Step Six: The three-dimensional orientation of the crystal can be determined by the crystal plane (111) and the [01_1] crystal orientation, such as... Figure 5 As shown in (c). Calculations using the formula for the angle between crystal planes show that the angle δ between the (111) plane and the (100) plane is 54.7°. In this case, if a single crystal element with the (100) plane needs to be cut out, the (111) plane only needs to be rotated 54.7° around the intersection line. Figure 6 The X-ray diffraction pattern of the (100) plane is determined to be the (100) plane.
[0064] Example 2
[0065] Taking the PMN-28PT crystal grown by the crucible lowering method as an example again, the following uses... Figure 1 The steps in the crystal orientation method flowchart shown are for three-dimensional orientation of the crystal.
[0066] Step 1: Cut a wafer from the PMN-28PT crystal.
[0067] Step 2: Perform powder X-ray diffraction on the cut crystal. The resulting powder X-ray diffraction pattern is shown below. Figure 2 As shown, the values were indexed. It should be noted that although PMN-28PT crystal has a trigonal crystal system, its cell parameter α is close to 90°, therefore it is also considered a pseudocubic phase. Therefore, it can be treated as a cubic crystal system during three-dimensional orientation. Simultaneously, full-spectrum X-ray diffraction was performed on the cut wafer, and the obtained X-ray diffraction pattern of the test wafer is shown below. Figure 3 As shown in (c). Through Figure 2 and Figure 3 The comparison in (c) revealed that the strongest peak in the X-ray diffraction pattern of the test wafer was the diffraction peak of the (110) plane;
[0068] Step 3: Fix the test wafer from Step 2 onto the X-ray orientation instrument and use the X-ray orientation instrument to obtain the deflection angle between the test wafer's crystal plane and the standard (110) plane. After obtaining the deflection angle, correct the cut surface of the crystal to be tested to obtain the accurate cut surface of the (110) plane. Figure 3 As shown in (d).
[0069] Step 4: Grind and polish the wafer with accurate (110) surface obtained in Step 3 to a thickness of 145μm. Place the polished wafer on the stage of a polarizing microscope to observe the extinction phenomenon of the polished wafer. Figure 5 This is an image of the polished disc (110) under a polarizing microscope, in which... Figure 7(a) is a diagram of a (110) polished wafer without an analyzer, with the wafer edge selected as the reference edge for the starting position (the oblique edge in the diagram); Figure 7 Image (b) shows the starting position of the (110) polishing disc under an orthogonal polarizing microscope. Figure 7 (c) is (110) polishing disc from Figure 7 The image in (b) is rotated 38° and viewed under an orthogonal polarizing microscope. At this point, the field of view is the darkest, indicating that the spontaneous polarization direction is consistent with the direction of the polarizer or analyzer. Figure 7 (d) is (110) polishing disc from Figure 7 The image in (c) is rotated 45° and viewed under an orthogonal polarizing microscope. At this point, the field of view is the brightest, indicating that the angle between the spontaneous polarization direction and the polarizer or analyzer direction is 45°.
[0070] Step 5: In this embodiment, the crystal plane (h1k1l1) is the (111) plane. Figure 5 The diagram in (d) shows the spontaneous polarization direction and (110) crystal plane of a pseudocubic PMN-28PT single crystal. Figure 5 In the diagram, (e) represents the projection of the spontaneous polarization direction onto the (110) plane. In this embodiment, the crystal plane (h2k2l2) can be selected as the (100) plane, and its intersection direction [uvw] is
[001] . Figure 5 As shown in (f). By comparison Figure 5 The projection of the spontaneous polarization direction onto the (110) plane in (e) and Figure 7 The projection direction of the spontaneous polarization determined in (110) can be used to determine the direction of the intersection line
[001] between the (110) and (100) planes, as shown in the figure. Figure 5 As shown in (f).
[0071] Step Six: The three-dimensional orientation of the crystal can be determined by the crystal plane (110) and the
[001] crystal orientation, such as... Figure 5 As shown in (f). Calculations using the formula for the angle between crystal planes show that the angle δ between the (110) and (100) crystal planes is 45°. In this case, if a single crystal element with the (100) plane needs to be cut out, the (110) plane only needs to be rotated 45° around the intersection line.
[0072] Example 3:
[0073] Taking the PMN-28PT crystal grown by the crucible lowering method as an example again, the following uses... Figure 1 The steps in the crystal orientation method flowchart shown are for three-dimensional orientation of the crystal.
[0074] Step 1: Cut a wafer from the PMN-28PT crystal.
[0075] Step 2: Perform powder X-ray diffraction on the cut crystal. The resulting powder X-ray diffraction pattern is shown below. Figure 2As shown, the values were indexed. It should be noted that although PMN-28PT crystal has a trigonal crystal system, its cell parameter α is close to 90°, therefore it is also considered a pseudocubic phase. Therefore, it can be treated as a cubic crystal system during three-dimensional orientation. Simultaneously, full-spectrum X-ray diffraction was performed on the cut wafer, and the obtained X-ray diffraction pattern of the test wafer is shown below. Figure 3 As shown in (e). Through Figure 2 and Figure 3 The comparison in (e) revealed that the strongest peak in the X-ray diffraction pattern of the test wafer was the diffraction peak of the (211) plane;
[0076] Step 3: Fix the test wafer from Step 2 onto the X-ray orientation instrument and use the X-ray orientation instrument to obtain the deflection angle between the test wafer's crystal plane and the standard (211) plane. After obtaining the deflection angle, correct the cut surface of the crystal to be tested to obtain the accurate cut surface of the (211) plane. Figure 3 As shown in (f).
[0077] Step 4: Grind and polish the wafer with the accurate (211) surface obtained in Step 3 to a thickness of 153μm. Place the polished wafer on the stage of a polarizing microscope to observe the extinction phenomenon of the polished wafer. Figure 8 This is an image of the polished disc (211) under a polarizing microscope, in which... Figure 8 (a) is a diagram of a (211) polished wafer without an analyzer. One side of the wafer is selected as the reference edge for the starting position (the horizontal edge in the diagram). Figure 8 Image (b) is an image of the (211) polished disc under an orthogonal polarizing microscope. Figure 8 (c) is (211) polishing sheet from Figure 8 The image in (b) is rotated 12° and viewed under an orthogonal polarizing microscope. At this point, the field of view is the darkest, indicating that the spontaneous polarization direction is consistent with the direction of the polarizer or analyzer. Figure 8 (d) is (211) polishing disc from Figure 8 The image in Figure (c) is rotated 45°. At this point, the field of view is the brightest, indicating that the angle between the spontaneous polarization direction and the polarizer or analyzer direction is 45°.
[0078] Step 5: In this embodiment, the crystal plane (h1k1l1) is the (211) plane. Figure 5 The diagram in (g) shows the spontaneous polarization direction and (211) crystal plane of a pseudocubic PMN-28PT single crystal. Figure 5 In this embodiment, the crystal plane (h2k2l2) can be selected as the (100) plane, and its intersection direction [uvw] is [01_1]. Figure 5 As shown in (i). By comparison Figure 5 (h) The projection of the spontaneous polarization direction onto the (211) plane and Figure 8The projection direction of the spontaneous polarization determined in (211) can be used to determine the direction of the intersection line [01_1] between the (211) and (100) planes, as shown in the figure. Figure 5 As shown in (i).
[0079] Step Six: The three-dimensional orientation of the crystal can be determined by the crystal plane (211) and the [01_1] crystal orientation, such as... Figure 5 As shown in (i). Calculations using the formula for the angle between crystal planes show that the angle δ between the (211) plane and the (100) plane is 35.3°. In this case, if a single crystal element with the (100) plane needs to be cut out, it is only necessary to rotate the (211) plane 35.3° around the intersection line.
[0080] The above three embodiments demonstrate three typical cases of three-dimensional orientation of ferroelectric crystals using this method. In actual operation, three-dimensional orientation can also be completed in other cases by following the basic orientation steps described in this method.
[0081] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.
Claims
1. A three-dimensional orientation method for ferroelectric crystals based on optical properties, characterized in that, Includes the following steps: 1) Cut a test wafer from the ferroelectric crystal under test; 2) Obtain the X-ray diffraction pattern of the cut surface of the test wafer, and determine the crystal plane index represented by the strongest diffraction peak in the X-ray diffraction pattern of the test wafer. h 1 k 1 l 1); 3) Obtaining information using an X-ray orientation instrument ( h 1 k 1 l 1) The angle between the crystal plane and the cut surface of the test wafer is used to correct the cut surface, resulting in a crystal plane index of ( ). h 1 k 1 l 1) The cut surface; 4) For ( h 1 k 1 l 1) The crystal surface was polished to a thickness ≤200μm. The extinction phenomenon of the polished wafer was observed using an orthogonal polarizing microscope to determine the spontaneous polarization of the polished wafer at ( h 1 k 1 l 1) The direction of the crystal plane projection; 5) Utilizing spontaneous polarization in ( h 1 k 1 l 1) The projection direction determines another crystal plane ( h 2 k 2 l 2) and ( h 1 k 1 l 1) The direction of the intersection line [ uvw ]; 6) Utilizing crystal planes ( h 1 k 1 l 1) The direction of the intersection of the two crystal planes [ uvw [To obtain the three-dimensional orientation of the crystal.] 2. The three-dimensional orientation method according to claim 1, characterized in that, The ferroelectric crystal to be tested is a single crystal without a natural growth surface.
3. The three-dimensional orientation method according to claim 1, characterized in that, The ferroelectric crystal under test exhibits spontaneous polarization.
4. The three-dimensional orientation method according to claim 1, characterized in that, The ferroelectric crystal under test is cubic, and the crystal plane ( h 2 k 2 l 2) and crystal planes ( h 1 k 1 l 1) The angle δ between the crystal planes satisfies the cubic crystal system formula: 。 5. The three-dimensional orientation method according to claim 1, characterized in that, The crystal plane ( h 2 k 2 l 2) and crystal planes ( h 1 k 1 l 1) The direction of the intersection line [ uvw ]satisfy: u = k 1 l 2 – l 1 k 2； v = l 1 h 2 – h 1 l 2； w = h 1 k 2 – k 1 h 2。