JP2014504246A - Template crystal grains of sheet-like lithium niobate titanate (Li-Nb-Ti-O), textured lithium niobate titanate (Li-Nb-Ti-O) microwave medium ceramics containing the same, and method for producing the same - Google Patents

Abstract

The present invention relates to a template crystal grain of sheet-like lithium niobate titanate (Li-Nb-Ti-O) and a method for producing the same, and the template crystal grain of the sheet-like Li-Nb-Ti-O has a chemical formula of LiNb. It is a powder of Li—Nb—Ti—O having a composition of _0.6 Ti _0.5 O ₃ , crystal grains in a sheet form, and an M-phase composition. Further, the present invention provides an organized lithium niobate titanate (Li—Nb—Ti—O) microwave medium ceramics containing the crystal grains and a method for producing the same.

Description

  The present invention belongs to the field of manufacturing template crystal grains of organized microwave medium ceramics and organized microwave medium ceramics containing the same, and is a lithium niobate titanate (Li-Nb-Ti-O) having a sheet-like crystal form , A textured lithium niobate titanate (Li—Nb—Ti—O) microwave medium ceramics and a method for producing the same.

Low-temperature co-fired ceramics (LTCC) microwave medium is a ceramic that is used as a medium material in a microwave frequency band (300 to 3000 GHz) circuit and performs one or more functions. It has characteristics such as a low coefficient and a high dielectric constant, and is used for elements such as a medium resonator, a medium filter, a duplexer, a microwave medium antenna, a medium resonance oscillator, and a medium waveguide. These elements are widely applied in many fields such as mobile communication, satellite television, broadcast communication, radar, and satellite positioning navigation system. As communications, computers, and peripheral products continue to develop into higher frequencies and digitalization, electronic devices are becoming smaller, more integrated, and modularized every day. LTCC will be the best choice for integration and modularization of electronic devices in the future because of its excellent electrical, mechanical, thermal and process properties. Li ₂ O—Nb ₂ O ₅ —TiO ₂ -based (LNT) microwave medium ceramics are characterized by dielectric constant tunability (20-78), high Q value, and resonant frequency temperature coefficient close to 0, etc. Has attracted widespread attention by researchers. High-functional microwave medium ceramics attract attention in fields such as modern communication and military technology, and are materials with application value and potential for development.

  The organization technique is to arrange ceramics originally randomly oriented in a certain direction so as to have a performance close to that of a single crystal by controlling the process. Currently, there are a template grain growth (TGG) technique and a reactive template grain growth (RTGG) technique as the most used ceramic organization techniques. The key process is the production of template grains. Template Grain Growth Technology (TGG) uses morphotropic anisotropic single crystal particles as a template, and a structure that induces orientation in template crystal grains developed following the template grain growth method and heat treatment technology. It is a conversion method. In general, anisotropic template crystal grains are manufactured by the molten salt method, and further, the cast or press method is used. make it happen. In the template crystal grain growth method, anisotropic template crystal grains are first manufactured. However, since the template crystal grain manufacturing requires a long-term searching process, it takes time and the process is complicated.

  However, until now, in this field, template crystal grains that have strong orientation and a large aspect ratio and can be suitably used for the production of structured microwave medium ceramics are also structured with strong orientation and organization characteristics. A method capable of producing a microwave medium ceramic and having a simple process has not been developed yet.

  For this reason, in this field, template crystal grains that have a strong orientation and a large aspect ratio and can be suitably used for the production of structured microwave medium ceramics, and a structured microwave medium having strong orientation and organization characteristics Development of a method that can produce ceramics and that has a simple process is eagerly desired.

  The present invention relates to a novel sheet-like lithium niobate titanate (Li-Nb-Ti-O) template crystal, and a structured lithium niobate titanate (Li-Nb-Ti-O) microwave medium ceramics And solving the problems in the existing technology by providing its manufacturing method.

On the other hand, in the present invention, the chemical formula is LiNb _0.6 Ti _0.5 O ₃ , the form of crystal grains is a sheet, and the composition is an M-phase Li—Nb—Ti—O powder. Template crystal grains of Li—Nb—Ti—O were provided.

  In one preferred embodiment, the shape of the crystal grains of the template crystal of the sheet-like Li—Nb—Ti—O is a sheet-like triangle or polygon.

  In another preferred embodiment, the above-mentioned sheet-like Li—Nb—Ti—O template crystal grains have a length in the diameter direction of 5 to 80 μm, an average length of 40 μm, and a thickness of 0.5 to 6.0 μm.

On the other hand, the present invention is a method for producing template crystal grains of the sheet-like Li-Nb-Ti-O,
Using Li ₂ CO ₃ , Nb ₂ O ₅ and TiO ₂ as raw materials, a LiClb molten salt system is used to synthesize sheet-like LiNb _0.6 Ti _0.5 O ₃ powder,
The obtained sheet-like LiNb _0.6 Ti _0.5 O ₃ powder was dispersed ultrasonically, washed with heated deionized water, suction filtered, and pure M-phase Li-Nb- By obtaining Ti—O powder, obtaining a template crystal grain of sheet-like Li—Nb—Ti—O,
A manufacturing method comprising:

In one preferred embodiment, the raw materials Li ₂ CO ₃ , Nb ₂ O ₅ and TiO ₂ are blended in a weight ratio of 0.5: 0.3: 0.5.

  In another preferred embodiment, a molten salt ratio of 1: 1 to 1: 3 is used in the LiCl molten salt system.

  In another preferred embodiment, in a molten salt system of LiCl, hold at 850 ° C. to 1000 ° C. for 3 to 9 hours.

  The present invention also provides a structured Li—Nb—Ti—O microwave medium ceramic comprising the sheet-like Li—Nb—Ti—O template crystal grains.

Further, the present invention is a method for producing the above-described structured Li—Nb—Ti—O microwave medium ceramics,
Producing template crystal grains of sheet-like Li—Nb—Ti—O by the method described above,
Li ₂ CO ₃ , Nb ₂ O ₅ , TiO ₂ as a powder raw material of the substrate, LiNb _0.6 Ti _0.5 O ₃ powder raw material was pre-synthesized,
Heat and stir the binder and solvent to form a clear solution,
The sheet-like LiNb _0.6 Ti _0.5 O ₃ template crystal grains and the pre-synthesized LiNb _0.6 Ti _0.5 O ₃ powder raw material are put into the transparent solution and uniformly mixed to obtain a slurry. ,
The above slurry is screen-printed on a substrate, heated and dried, and the resulting slurry film is cut, laminated and pressed to remove organic matter at 600 ° C to 800 ° C, and further cold isostatic pressure Performing pressure treatment and sintering to obtain a structured Li—Nb—Ti—O microwave medium ceramic;
A manufacturing method comprising:

In one preferred embodiment, the powder raw material of LiNb _0.6 Ti _0.5 O ₃ is pre-synthesized by holding at 850 ° C. for 2 hours.

In another preferred embodiment, when calculated by weight, the binder: solvent: slurry = 1: 12-25: 5-15, and the template crystal grains of sheet-like LiNb _0.6 Ti _0.5 O _{3 in} the slurry. The ratio occupied by is 5-15%.

  In another preferred embodiment, the binder is selected from ethyl cellulose, methyl cellulose and nitrocellulose, and the solvent is selected from terpineol and ethylene glycol.

  In another preferred embodiment, the mixing is a ball mill mixing and the screen printing is performed on a 300 mesh screen.

  In another preferred embodiment, the sintering is performed at 1000-1150 ° C. with a heating rate of 3-6 ° C./min and held at temperature for 2-5 hours.

FIG. 1 shows an M-phase LiNb _0.6 Ti _0.5 O ₃ template synthesized at different temperatures with a molten salt ratio of 1: 2, a heat retention time of 3 hours, according to one embodiment of the present invention. It is a XRD (X-ray diffraction) spectrum of a crystal grain. Here, (a) is an XRD spectrum of a template crystal grain synthesized at 850 ° C, (b) is an XRD spectrum of a template crystal grain synthesized at 950 ° C, and (C) is synthesized at 1000 ° C. (D) is an XRD spectrum of the template crystal grain synthesized at 1050 ° C. FIG. 2 is a diagram of M-phase LiNb _0.6 Ti _0.5 O ₃ synthesized at different temperatures with a molten salt ratio of 1: 2 and a heat retention time of 3 hours according to one embodiment of the present invention. It is a SEM (scanning electron microscope) photograph of a template crystal grain. Here, (a) is an SEM photograph of template crystal grains synthesized at 850 ° C, (b) is an SEM photograph of template crystal grains synthesized at 950 ° C, and (C) is synthesized at 1000 ° C. (D) is an SEM photograph of the template crystal grains synthesized at 1050 ° C. FIG. 3 shows an M-phase LiNb _0.6 Ti _0.5 O ₃ synthesized at different incubation times at a temperature of 1000 ° C. with a molten salt ratio of 1: 2 according to one embodiment of the present invention. It is an XRD spectrum of the template crystal grain. Here, (e) is an XRD spectrum of template crystal grains synthesized with a heat retention time of 3 hours, (f) is an XRD spectrum of template crystal grains synthesized with a heat retention time of 6 hours, and (g) is a heat retention time of 9 hours. 3 is an XRD spectrum of template crystal grains synthesized in time. FIG. 4 shows an M-phase LiNb _0.6 Ti _0.5 O ₃ synthesized with different incubation times at a temperature of 1000 ° C. with a molten salt ratio of 1: 2 according to one embodiment of the present invention. It is a SEM photograph of the template crystal grain of. Here, (e) is a SEM photograph of template crystal grains synthesized with a heat retention time of 3 hours, (f) is a SEM photograph of template crystal grains synthesized with a heat retention time of 6 hours, and (g) is a heat retention time of 9 hours. It is a SEM photograph of the template crystal grain synthesized with time. FIG. 5 is a diagram of M-phase LiNb _0.6 Ti _0.5 O ₃ synthesized at different molten salt ratios at a temperature of 1000 ° C., a heat retention time of 6 hours, according to one embodiment of the present invention. It is an XRD spectrum of a template crystal grain. Here, (h) is an XRD spectrum of a template crystal grain synthesized with a molten salt ratio of 1: 1, and (i) is an XRD spectrum of a template crystal grain synthesized with a molten salt ratio of 1: 2. , (J) are XRD spectra of template crystal grains synthesized at a molten salt ratio of 1: 3. FIG. 6 shows M-phase LiNb _0.6 Ti _0.5 O ₃ synthesized at different molten salt ratios at a temperature of 1000 ° C. with a heat retention time of 6 hours according to one embodiment of the present invention. It is a SEM photograph of a template crystal grain. Here, (h) is an SEM photograph of template crystal grains synthesized with a molten salt ratio of 1: 1, and (i) is an SEM photograph of template crystal grains synthesized with a molten salt ratio of 1: 2. , (J) are SEM photographs of template crystal grains synthesized at a molten salt ratio of 1: 3. FIG. 7 is an XRD (X-ray diffraction) spectrum of LNT ceramics produced by a conventional method. FIG. 8 is an XRD spectrum of the structured LNT ceramic produced by the method of the present invention. Here, b is an XRD spectrum of the structured LNT ceramic perpendicular to the screen printing surface, and C is an XRD spectrum of the structured LNT ceramic parallel to the screen printing surface. From FIG. 8, the parallel and perpendicular diffraction peaks of the structured LNT ceramics have the same position, but the strength is clearly different, and the (202) peak parallel to the surface of the screen print is remarkably enhanced, resulting in strong organization. It can be seen that there is a feature. FIG. 9 is an SEM (scanning electron microscope) diagram of template crystal grains used in the present invention. From the SEM analysis of FIG. 9, the LNT crystal grains are sheet-like, the length in the diameter direction is 5 to 30 μm, the thickness is 0.5 to 2.0 μm, and has a large aspect ratio, which is an ideal TGG. And template crystal grains suitable for application of reactive template grain growth (RTGG) technology. FIG. 10 is an SEM view (1100 ° C., 2 hours sintering) of structured LNT ceramic parallel to the screen printed surface, according to one embodiment of the present invention. From FIG. 10, it can be seen that the sheet-like ceramic template increases remarkably in that direction, and the crystal grain diameter becomes 50 to 60 μm. FIG. 11 is a SEM view (1100 ° C., 2 hours sintering) of textured LNT ceramics perpendicular to the screen printed surface, according to one embodiment of the present invention. From FIG. 11, the sheet-like ceramic template is remarkably increased in both the diameter direction and the thickness direction, the crystal grain diameter is 60 to 80 μm, the average length is about 40 μm, and the thickness is 2 to 6 It can be seen that there is a remarkable organization characteristic at 0.0 μm and alignment. FIG. 12 is a dielectric temperature spectrum obtained by measuring a slice along a vertical and parallel direction of a sintered microwave medium ceramic with a silver plated electrode according to one embodiment of the present invention. Here, a is perpendicular to the crystal grain arrangement direction, and b is parallel to the crystal grain arrangement direction. From FIG. 12, at a frequency of 1 MHz, a dielectric constant ε = 55.75 in a direction perpendicular to the crystal grain arrangement direction and a positive dielectric constant temperature coefficient, but in a direction parallel to the crystal grain arrangement direction. It can be seen that the dielectric constant ε = 84.40 and the dielectric constant temperature coefficient is negative. The relationship between the resonance frequency temperature coefficient τ _f , the dielectric constant temperature coefficient τ _ε and the thermal expansion coefficient α ₁ is τ _f = −1 / 2τ _ε −α ₁ , and usually α ₁ is 6 to 9 ppm / ° C. Therefore, it is presumed that it has a resonance frequency temperature coefficient close to a negative value of 0 in the direction perpendicular to the crystal grain arrangement direction and a resonance frequency temperature coefficient close to a positive value of 0 in the direction parallel to the crystal grain arrangement direction. Is done.

The inventors of the present invention have studied extensively and deeply. As a result, M-phase LiNb _0.6 Ti _0.5 O ₃ (LNT) microwave medium ceramics have a high dielectric constant (about 70) and a sintering temperature. It was found to have a low Q value of about 1100 ° C. and at the same time a high Q value and a resonance frequency temperature coefficient close to 0 (about 8 ppm / ° C.). By the organization technique, the crystal grains of ceramics are arranged in a certain direction and show excellent anisotropy. At a frequency of 1 MHz, the dielectric constant ε = 55.8 in the direction perpendicular to the crystal grain arrangement direction, and the dielectric constant ε = 84.4 in the direction parallel to the crystal grain arrangement direction. By different methods of cutting, ceramics having different dielectric constants can be obtained, and microwave medium ceramics having a resonance frequency temperature coefficient of 0, low wear, and excellent electrical functions can be obtained. The template material used for LNT microwave medium ceramics is LNT powder having a sheet-like form. The M-phase LiNb _0.6 Ti _0.5 O ₃ powder produced by the molten salt method has a similar structure to LiNbO ₃ and belongs to the pseudotrigonal system, and the structure of the powder is an n-layer structure. LiNbO ₃ (LN layer) and the intervening component are both composed of a corundum type structure close to [Ti ₂ O ₃ ] ²⁺ , and are large in the form of polygonal crystal grains that are sheet-like and combined with triangles or triangles It is a template crystal grain that has an aspect ratio and strong orientation and is used for ideal LNT microwave medium ceramics. Moreover, the orientation growth technology of the template crystal grains can control the growth direction of the crystal grains by improving the microstructure of the ceramics and form ceramics with a high degree of orientation and organization. The sheet-like LiNb _0.6 Ti _0.5 O ₃ formed by the above method is used as a template, mixed with pre-sintered Li ₂ CO ₃ , Nb ₂ O ₅ , TiO _2, and further added with a sintering aid, By cutting, laminating, removing the binder, and sintering the ceramic thick film obtained by screen printing, an organized Li-Nb-Ti-O ceramic is obtained, and the structured microwave medium ceramics The density and orientation can be improved, and the dielectric constant, dielectric constant temperature coefficient, and resonance frequency temperature coefficient of ceramics are all markedly anisotropic. Shows, the cutting of the different directions, the dielectric constant becomes series of can function to obtain an excellent microwave medium ceramics. Based on the above findings, the present invention has been completed.

In the first aspect of the present invention, the chemical formula is LiNb _0.6 Ti _0.5 O ₃ , the crystal grains are in sheet form, the length in the diameter direction is 5 to 80 μm, and the thickness is 0.5 to 6. At 0 μm, a Li—Nb—Ti—O powder having a large aspect ratio and strong orientation and being a template crystal grain suitable for an ideal TGG and RTGG technology was provided.

The second of the present invention is a method for producing the aforementioned Li-Nb-Ti-O powder,
Li ₂ CO ₃ , Nb ₂ O ₅ and TiO ₂ are used as raw material powders, blended according to the following reaction equation,
0.5Li ₂ CO ₃ + 0.3Nb ₂ O ₅ + 0.5TiO ₂ → LiNb _0.6 Ti _0.5 O ₃
Mixed raw material: absolute ethanol: ZrO ₂ balls = 1: 2: 3 mixed in a ball mill, heat-dried and sized, then put LiCl with a weight ratio of 1: 1 to 1: 3, polished and even The mixture is heated to 850 to 1100 ° C. at a rate of 5 ° C./min, and the temperature is maintained for 3 to 9 hours, whereby the sheet-like LiNb _0.6 Ti _0.5 O ₃ powder is obtained. Obtained,
The synthesized LiNb _0.6 Ti _0.5 O ₃ powder was dispersed by ultrasonic waves, washed with heated deionized water, and filtered several times with suction, and then the LiCl molten salt in the system was removed by filtration. And drying in an oven to obtain the desired sheet-like LiNb _0.6 Ti _0.5 O ₃ template crystal grains,
A manufacturing method comprising:

In the present invention, the crystal phase structure of LiNb _0.6 Ti _0.5 O ₃ template under different conditions by XRD and the microscopic structure of these powders were analyzed by SEM. As a result, it was found that the production method of the present invention succeeded in producing template crystal grains of LiNb _0.6 Ti _0.5 O ₃ having morphological characteristics of sheet-like crystal grains. By SEM analysis, LNT crystal grains are in sheet form, length in diameter direction is 5-30 μm, thickness is 0.5-2.0 μm, have a large aspect ratio, and ideal TGG and RTGG application It was found that the template crystal grains are suitable for the above.

  The powder of lithium niobate titanate produced by the method of the present invention can be made into template crystal grains of organized Li—Nb—Ti—O microwave medium ceramics of various types of compositions. It is possible to obtain a microwave medium ceramic that has a positive effect on improving the density and mechanical strength of ceramics, has remarkable anisotropy, and has low dielectric properties and excellent dielectric properties.

In the third aspect of the present invention, the chemical formula is LiNb _0.6 Ti _0.5 O ₃ , the form of the crystal grains is a sheet, the length in the diameter direction reaches a maximum of 80 μm, and the average length is about 40 μm. The present invention provides a Li—Nb—Ti—O microwave medium ceramics having a thickness of 2 to 6.0 μm and strong orientation and texture characteristics.

In the present invention, a microwave medium ceramic material of Li—Nb—Ti—O having a high density and a high degree of orientation can be produced under a condition where a template is added. Simplified. In the present invention, a pure M-phase having a high degree of orientation and anisotropy is obtained by adding template crystal grains of LiNb _0.6 Ti _0.5 O _{3 at} a predetermined ratio to the pre-synthesized LNT powder. LiNb _0.6 Ti _0.5 O ₃ microwave medium ceramics are manufactured. The aforementioned LiNb _0.6 Ti _0.5 O ₃ is composed of an n-layer LiNbO ₃ (LN) and a corundum structure in which the component interposed between the layers is close to [Ti ₂ O ₃ ] ²⁺ .

  The Li—Nb—Ti—O microwave medium ceramics obtained by the present invention has a remarkable anisotropy in the directions of dielectric and vertical and parallel. It was cut into slices in the vertical and parallel directions, silver paste was applied on both sides, and sintered at a temperature of 700 to 750 ° C. for 30 minutes on a silver plating electrode. When measured with a network analyzer, it has a dielectric constant ε = 55.75 and a positive dielectric constant temperature coefficient in a direction perpendicular to the crystal grain arrangement direction at a frequency of 1 MHz, but parallel to the crystal grain arrangement direction. It was found that the dielectric constant was ε = 84.40 and had a negative dielectric constant temperature coefficient.

A fourth aspect of the present invention is a method for producing the aforementioned Li-Nb-Ti-O microwave medium ceramics,
Li ₂ CO ₃ , Nb ₂ O ₅ and TiO ₂ are used as raw material powders, blended according to the following reaction equation,
0.5Li ₂ CO ₃ + 0.3Nb ₂ O ₅ + 0.5TiO ₂ → LiNb _0.6 Ti _0.5 O ₃
Mixed raw material: absolute ethanol: ZrO ₂ balls = 1: 2: 3 is mixed by a ball mill, heated and dried, sized, and preliminarily synthesized at 700 to 900 ° C.,
Calculated by the reaction equation of LiNb _0.6 Ti _0.5 O ₃ , the raw materials were weighed so that the molar ratio was Li ₂ CO ₃ : Nb ₂ O ₅ : TiO ₂ = 5: 3: 5, and LiCl molten salt M-phase sheet-like LiNb _0.6 Ti _0.5 O ₃ template was synthesized by the molten salt method in the environment of
Using ethyl cellulose as a binder and terpineol as a solvent, heating and stirring at 80 ° C. until a transparent solution is obtained, placing the pre-synthesized powder in the above solution, and mixing uniformly for 2 to 4 hours with a ball mill, Finally, template crystal grains were added at a predetermined ratio, and ball milling was continued for 2 hours to obtain a required slurry. The slurry was printed directly on the substrate with a 300 mesh screen and dried in an oven at 80-100 ° C. The above process is repeated 50 to 80 times to obtain a mixed raw material thick film having a thickness of 0.5 to 1 mm (seed crystals are arranged in a direction parallel to the substrate by the action of the shearing force of the screen), and finally ceramics. The thick film was dried in an oven at 80-100 ° C for 10-20 hours. A manufacturing method comprising cutting a ceramic film into a required size, taking it from a substrate, press-molding it over a polishing tool, and placing the formed dough in a heat treatment furnace to remove organic matter at 600 to 800 ° C. Provided.

  In the present invention, the sintering process raises the temperature to 1100-1140 ° C. at a rate of 5-10 ° C./min, sinters the sample, and holds the temperature for 2-10 hours.

  In the present invention, the structured Li—Nb—Ti—O microwave medium ceramics was successfully manufactured. When XRD analysis was performed in a grain boundary parallel to the ceramics and in a vertical direction, the ceramic material was found to have a (202) plane ( It was found that there is a remarkable organization phenomenon along (see FIG. 2). In the SEM analysis, the crystal grains are in sheet form, the length in the diameter direction reaches up to 80 μm, the average length is about 40 μm, the thickness is 2 to 6.0 μm, strong orientation and It was seen that it had the characteristics of organization.

  The main advantages of the present invention are as follows.

1. The present invention has produced for the first time M-phase LiNb _0.6 Ti _0.5 O ₃ template crystal grains similar to the LiNbO ₃ structure, and the crystal grains have a strong orientation and a large aspect ratio. When used in the manufacture of structured LiNb _0.6 Ti _0.5 O ₃ microwave medium ceramics, the density and orientation of the structured microwave medium ceramics can be improved. Microwave medium ceramics having low wear and temperature coefficient of resonance frequency close to 0 and adjustable dielectric constant within a certain range can be obtained, and multilayer microwave frequencies such as filters, sheet-type medium resonators and antennas can be obtained. Suitable for device manufacturing and has a wide range of potential applications.

  2. The raw materials used in the present invention are low in price, easy to manufacture and easy to spread.

  3. The thickness of the Li—Nb—Ti—O microwave ceramic film layer produced by the present invention is suppressed to several microns, and in a single film layer, the crystal grains are oriented properly by the action of the shearing force of printing. can do.

  4. The Li—Nb—Ti—O microwave ceramics produced by the present invention has a larger crystal grain size than the Li—Nb—Ti—O microwave ceramics produced by the conventional method. It has remarkable directivity, high degree of orientation, and at the same time excellent electrical performance.

  5. Compared with the casting process, the present invention is simple in slurry preparation, simple in process, easy to control and low in cost.

  6. The method of the present invention can improve the density and degree of orientation of the structured microwave medium ceramics, and the dielectric constant, dielectric constant temperature coefficient, and resonance frequency temperature coefficient of the ceramics have significant anisotropy. By cutting in different directions, the dielectric constant becomes a series, and microwave medium ceramics with excellent performance can be obtained, suitable for manufacturing multilayer microwave frequency elements such as filters, sheet type medium resonators and antennas It is expected to be applied to many fields such as mobile communication, satellite positioning navigation system, etc., and has the potential for wide development and future of application.

  Hereinafter, the present invention will be further described with reference to specific examples. However, it should be understood that these examples are illustrative of the invention and are not a limitation on the scope of the invention. In the following examples, the test methods in which specific conditions are not described were usually performed under normal conditions or conditions recommended by the manufacturer. Unless stated otherwise, all percentages and parts are calculated by weight.

Example 1
(I) Synthesis of template crystal grains: calculated by the reaction equation of LiNb _0.6 Ti _0.5 O _{3 so} that the molar ratio is Li ₂ CO ₃ : Nb ₂ O ₅ : TiO ₂ = 5: 3: 5 The raw materials were weighed and mixed with ethanol and ZrO ₂ balls at a ratio of 1: 2: 3 for 24 hours in a ball mill, then transferred to a glass container and dried by heating at 90 ° C. After the dried raw material powder was sized, LiCl salt was added at a ratio of 1: 2 and polished for 10 minutes until uniformly mixed. The mixed raw material was placed in an Al ₂ O ₃ crucible, covered, and synthesized in a high temperature furnace at 850 to 1050 ° C. for 3 hours at a temperature rising rate of 3 ° C./min.
(Ii) Filtration of template crystal grains: The synthesized LiNb _0.6 Ti _0.5 O ₃ crystal grains are pulverized, dispersed ultrasonically, washed 10 times with heated deionized water, and LiCl melted therein Salt was removed. Meanwhile, the content of Cl ⁻ ions in the filtrate was measured with an AgNO ₃ solution to determine whether filtration was complete. FIG. 1 is an XRD spectrum of the manufactured LiNb _0.6 Ti _0.5 O ₃ template crystal grain. From FIG. 1, the crystal grain XRD spectrum at 850 ° C. shows other temperatures except for a slight impurity peak. It can be seen that all of the crystal grains synthesized in (1) were a single M-phase. The SEM photograph is shown in FIG. 2. From FIG. 2, the crystal grains of LiNb _0.6 Ti _0.5 O ₃ are in the form of a sheet and the crystal plane is a polygon or a combination of triangles. This is because LiNbO ₃ belongs to a structure similar to the trigonal structure of LiNbO ₃ . As the synthesis temperature increased, the crystal grains increased to some extent in both the diameter direction and the thickness direction.

Example 2
The raw material was weighed so that the molar ratio was Li ₂ CO ₃ : Nb ₂ O ₅ : TiO ₂ = 5: 3: 5, calculated by the reaction equation of LiNb _0.6 Ti _0.5 O ₃ , ethanol, ZrO After mixing for 24 hours with a ball mill at a ratio of ₂ balls to 1: 2: 3, the mixture was transferred to a glass container and dried by heating at 90 ° C. After the dried raw material powder was sized, LiCl salt was added at a ratio of 1: 2 and polished for 10 minutes until uniformly mixed. Put the mixed raw material in an Al ₂ O ₃ crucible, cover it, raise it to 1000 ° C. at a heating rate of 3 ° C./min in a high temperature furnace, hold the temperature for 3 hours, 6 hours and 9 hours, respectively, and take it out Then, it was filtered by the method of Example 1. FIG. 3 is an XRD spectrum of LiNb _0.6 Ti _0.5 O ₃ template crystal grains obtained at different incubation times. From FIG. 3, all synthesized grains were single M-phase. I understand that. The SEM photograph is shown in FIG. 4. The crystal grains showed a stepwise growth tendency, and the crystal grains increased to some extent in the diameter direction and the thickness direction as the heat retention time increased.

Example 3
The raw material was weighed so that the molar ratio was Li ₂ CO ₃ : Nb ₂ O ₅ : TiO ₂ = 5: 3: 5, calculated by the reaction equation of LiNb _0.6 Ti _0.5 O ₃ , ethanol, ZrO After mixing for 24 hours with a ball mill at a ratio of ₂ balls to 1: 2: 3, the mixture was transferred to a glass container and dried by heating at 90 ° C. After the dried raw material powder was sized, LiCl salts were added at a ratio of 1: 1, 1: 2, and 1: 3, respectively, and polished for 10 minutes until they were uniformly mixed. The mixed raw material was put in an Al ₂ O ₃ crucible, covered, raised to 1000 ° C. at a temperature rising rate of 3 ° C./min in a high-temperature furnace, held at temperature for 6 hours, and taken out. Filtered by the method. FIG. 5 is an XRD spectrum of LiNb _0.6 Ti _0.5 O ₃ template grains obtained at different molten salt ratios. From FIG. 3, all synthesized grains have a single M- It turns out that it was a phase. The SEM photograph is shown in FIG. 6, and the crystal grains show a step-like growth tendency, and the crystal grains increase to some extent in the diameter direction and the thickness direction as the ratio of the molten salt increases. Then, the increase is remarkable. When the ratio of the molten salt was 1: 3, the crystal grains of the obtained LNT template reached 2-3 μm. The LiNb _0.6 Ti _0.5 O ₃ powder crystal grains were sufficiently completed, but the crystal grains obtained by maintaining the temperature at 1000 ° C. for 6 hours at a molten salt ratio of 1: 2 It is an ideal template crystal grain in the form of a sheet-like polygon, having a length in the diameter direction of 5 to 30 μm, a thickness of 0.5 to 2.0 μm, and a large aspect ratio.

Example 4
Production of LiNb _0.6 Ti _0.5 O ₃ microwave medium ceramics by a conventional method: Calculated by the reaction equation of LiNb _0.6 Ti _0.5 O ₃ and the molar ratio is Li ₂ CO ₃ : Nb ₂ O ₅ : Weighed the raw materials so that TiO ₂ = 5: 3: 5, mixed with ethanol and ZrO ₂ balls at a ratio of 1: 2: 3 for 24 hours in a ball mill, then transferred to a glass container and heated at 90 ° C. Dried. After the dried raw material powder was sized, it was put in a crucible and pre-sintered at 700 to 1000 ° C. for 5 to 7 hours to synthesize a main crystal phase. Ethanol is added so that the weight ratio of the mixed raw material and ethanol is 1: 2, mixed in a wet ball mill for 24 hours, heated and dried at 100 to 120 ° C., and granulated with 8-12% PVB (polyvinyl butyral). , Pressed into a small cylinder of φ16 × 8 mm at a pressure of 100 to 200 MPa, removed the binder at 600 to 700 ° C., sintered at 860 to 960 ° C. for 1 to 3 hours, naturally cooled, and LiNb _0.6 A Ti _0.5 O ₃ microwave medium ceramic was obtained. When the dielectric property of the ceramic sample was measured by the Hakki-Coleman cylindrical medium resonance method, the dielectric constant was 71 and the resonant frequency temperature coefficient was 10.5 ppm / ° C. (see FIG. 7).

Example 5
Production of LNT structured microwave medium ceramics by screen printing:
(1) Preparation of slurry: 3.43 g of ethyl cellulose was dissolved in 76.54 g of terpineol, and the mixture was heated and stirred at 80 ° C. until the ethyl cellulose was completely dissolved and became a transparent solution. 31.59 g of LiNb _0.6 Ti _0.5 O ₃ powder pre-synthesized at 850 ° C. was weighed, put into the above solution, and uniformly mixed for 4 hours by a ball mill. Further, 3.51 g of sheet-like LiNb _0.6 Ti _0.5 O ₃ template crystal grains were put into the slurry and then mixed for 2 hours in a ball mill.
(2) Screen printing: The prepared slurry is printed on a terylene film with a 300-mesh screen, dried in a 100 ° C. oven, the above steps are repeated 50 to 80 times, and finally a ceramic film of about 1 mm is formed. Been formed.
(3) Molding: The obtained ceramic film was cut into a square sheet of 11 mm × 11 mm, the film was removed from the substrate, and about 50 layers were stacked and press molded.
(4) Binder removal and sintering: The ceramic material was placed in a heat treatment furnace and organic substances were removed at 650 ° C. The sample from which the binder was removed was subjected to a cold isostatic pressing treatment, placed in a high temperature furnace, heated to 1135 ° C. at a rate of 10 ° C./min, and maintained at the temperature for 2 hours.
With the organization technique, the crystal grains of ceramics were arranged in a certain direction and showed excellent anisotropy. At a frequency of 1 MHz, with a dielectric constant ε = 55.75 in a direction perpendicular to the arrangement direction, a positive dielectric constant temperature coefficient and a negative resonance frequency temperature coefficient, but in a direction parallel to the arrangement direction, It had a dielectric constant ε = 84.40, a negative dielectric constant temperature coefficient, and a positive resonant frequency temperature coefficient. By different methods of cutting, ceramics having different dielectric constants can be obtained, and microwave medium ceramics having a resonance frequency temperature coefficient of 0, low wear, and excellent electrical performance can be obtained ( See Figures 8-12).

  All documents according to the present invention are cited in this application as a reference, so that each document is individually cited. In addition, after reading the above description of the present invention, engineers in this field can make various changes and modifications to the present invention, but those equivalent aspects are within the scope of the present invention. It should be understood that it is included.

Claims (14)

Sheet-form Li-Nb-Ti-, which is a Li-Nb-Ti-O powder having a chemical formula of LiNb _0.6 Ti _0.5 O ₃ , crystal grains in a sheet form, and an M-phase composition. Template crystal grains of O.   2. The sheet-like Li—Nb—Ti—O of the sheet-like Li—Nb—Ti—O has a shape of a crystal grain of a sheet-like triangle or polygon. Template crystal grain.   The sheet-like Li—Nb—Ti—O template crystal grains have a length in the diameter direction of 5 to 80 μm, an average length of 40 μm, and a thickness of 0.5 to 6.0 μm. The template crystal grain of the sheet-like Li-Nb-Ti-O according to claim 1 or 2. A method for producing a template crystal grain of sheet-like Li-Nb-Ti-O according to any one of claims 1 to 3,
Using Li ₂ CO ₃ , Nb ₂ O ₅ and TiO ₂ as raw materials, a LiCl molten salt system was used to synthesize sheet-like LiNb _0.6 Ti _0.5 O ₃ powder,
The obtained sheet-like LiNb _0.6 Ti _0.5 O ₃ powder was dispersed ultrasonically, washed with heated deionized water, suction filtered, and pure M-phase Li-Nb- By obtaining Ti—O powder, obtaining a template crystal grain of sheet-like Li—Nb—Ti—O,
Manufacturing method. The method according to claim 4, wherein the raw materials, Li ₂ CO ₃ , Nb ₂ O ₅ and TiO _2, are blended in a molar ratio of 5: 3: 5.   5. The method according to claim 4, wherein a ratio of 1: 1 to 1: 3 molten salt is used in the LiCl molten salt system.   The method according to claim 4, wherein the molten salt system of LiCl is held at 850 ° C to 1000 ° C for 3 to 9 hours.   An organized Li-Nb-Ti-O microwave medium ceramic comprising the sheet-like Li-Nb-Ti-O template crystal grain according to any one of claims 1 to 3. A method for producing the structured Li-Nb-Ti-O microwave medium ceramic according to claim 8,
A template crystal of sheet-like Li-Nb-Ti-O is produced by the method according to any one of claims 4 to 7,
Li ₂ CO ₃ , Nb ₂ O ₅ , TiO ₂ as a powder raw material of the substrate, LiNb _0.6 Ti _0.5 O ₃ powder raw material was pre-synthesized,
Heat and stir the binder and solvent to form a clear solution,
Sheet-like LiNb _0.6 Ti _0.5 O ₃ template crystal grains and pre-synthesized LiNb _0.6 Ti _0.5 O ₃ powder raw material are put into the transparent solution and uniformly mixed to obtain a slurry. ,
The above slurry is screen-printed on a substrate, heated and dried, and the resulting slurry film is cut, laminated and pressed to form organic matter, remove organic matter at 600 to 800 ° C, and further cold isostatically pressurized Processing and sintering to obtain a structured Li—Nb—Ti—O microwave medium ceramic;
Manufacturing method. The method according to claim 9, wherein the powder raw material of LiNb _0.6 Ti _0.5 O ₃ is pre-synthesized by holding at 850 ° C. for 2 hours. When calculated by weight, binder: solvent: slurry = 1: 12-25: 5-15, and the ratio of template crystal grains of sheet-like LiNb _0.6 Ti _0.5 O _{3 in} the slurry is 5-15%. The method of claim 9, wherein:   The method according to any one of claims 9 to 11, wherein the binder is selected from ethyl cellulose, methyl cellulose, and nitrocellulose, and the solvent is selected from terpineol and ethylene glycol.   12. The method according to claim 9, wherein the mixing is performed by a ball mill, and the screen printing is performed by a 300 mesh screen.   The said sintering is sintered at 1000-1150 degreeC with the temperature increase rate of 3-6 degreeC / min, and hold | maintains temperature for 2 to 5 hours, It is characterized by the above-mentioned. The method described in 1.

Images