A high-conductivity lithium tantalate wafer and a method for preparing the same

Abstract

The invention discloses a lithium tantalate wafer with high electrical conductivity and a preparation method thereof, belonging to the technical field of crystal materials. The invention comprises the following steps: uniformly mixing an organic carbon source, an inorganic carbon source and spherical zinc powder to obtain a reducing agent; embedding the reducing agent on the surface of the lithium tantalate wafer, placing the wafer in a heat treatment furnace, introducing an inert gas for carbonization; introducing a reducing gas for heat treatment, taking the wafer out, and obtaining the lithium tantalate wafer with high electrical conductivity; the organic carbon source comprises at least one of sucrose and phenolic resin; the inorganic carbon source comprises at least one of flaky graphite and graphene; the invention uses an organic carbon source, an inorganic carbon source and spherical zinc powder in a mass ratio of 1: (0.3-0.6): (0.4-0.7) as a reducing agent, embeds the reducing agent on the surface of the lithium tantalate wafer, firstly undergoes carbonization, and then undergoes heat treatment, so as to effectively improve the electrical conductivity of the lithium tantalate wafer and has broad application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of crystal materials, and in particular to a lithium tantalate wafer with high electrical conductivity and a preparation method thereof. Background Art

[0002] Lithium tantalate has good mechanical and physical properties, and also has the advantage of low production cost. It has been widely used in the field of functional electronic materials. Lithium tantalate is a crystal that integrates nonlinear optics, piezoelectricity, acousto-optics and other properties. It is an important functional electronic material and is widely used in resonators, infrared devices, filters and other products.

[0003] Traditional lithium tantalate materials have excellent piezoelectric and nonlinear optical properties, but their low electrical conductivity limits their performance in certain high-frequency, high-current applications. With the development of science and technology, higher conductivity requirements are put forward for lithium tantalate materials to meet the needs of modern electronic devices, especially in the fields of energy storage, transmission and sensors. Therefore, how to improve the conductivity of lithium tantalate chips has become an urgent problem to be solved.

[0004] In view of this, this application is filed. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a lithium tantalate wafer with high electrical conductivity and a preparation method thereof. The method described in the present invention can significantly improve the electrical conductivity of the lithium tantalate wafer.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for preparing a lithium tantalate wafer with high electrical conductivity comprises the following steps:

[0008] The organic carbon source, the inorganic carbon source and the spherical zinc powder are mixed uniformly to obtain a reducing agent;

[0009] The reducing agent is embedded in the surface of the lithium tantalate wafer, placed in a heat treatment furnace, and an inert gas is introduced for carbonization; a reducing gas is then introduced for heat treatment, and the wafer is taken out to obtain a lithium tantalate wafer with high conductivity;

[0010] The organic carbon source includes at least one of sucrose and phenolic resin;

[0011] The inorganic carbon source includes at least one of flake graphite and graphene;

[0012] The mass ratio of the organic carbon source, the inorganic carbon source and the spherical zinc powder is 1: (0.3-0.6): (0.4-0.7).

[0013] The present invention uses an organic carbon source, an inorganic carbon source and spherical zinc powder in a mass ratio of 1: (0.3-0.6): (0.4-0.7) as a reducing agent, embeds them on the surface of a lithium tantalate wafer, first undergoes carbonization and then undergoes heat treatment, which can effectively improve the conductivity of the lithium tantalate wafer and has broad application prospects.

[0014] The present invention uses an organic carbon source, an inorganic carbon source, and spherical zinc powder in a mass ratio of 1: (0.3-0.6): (0.4-0.7) as a reducing agent, and the reducing agent can chemically react with the lithium tantalate wafer to change its internal structure, causing some ions in the crystal to change their valence state, resulting in an increase in the number of free valence electrons. These free electrons can move under the action of an external electric field, neutralize the charge generated by the pyroelectric effect, reduce the pyroelectric effect, and thus significantly improve the conductivity of the lithium tantalate wafer.

[0015] In the present invention, during the treatment process, the inorganic carbon source is carbonized to become hard carbon with strong reducing properties. During the treatment process, C atoms enter the wafer and bond with Ta to form light brown TaC. The interface between TaC and LiTaO3 and the dispersion of light by TaC can further enhance the dispersion of light, resulting in the formation of black LiTaO3 wafers to generate TaC, and forming enough oxygen vacancies to reduce the band gap of the material, fill the conduction band between the full band and the empty band, and then significantly improve the conductivity of the lithium tantalate wafer through the formation of TaC and O vacancies.

[0016] As a preferred embodiment of the present invention, the organic carbon source includes sucrose and phenolic resin, and the mass ratio of the sucrose to the phenolic resin is 1: (0.5~2). In particular, when sucrose and phenolic resin are used as organic carbon sources, the generation of hard carbon can be increased, the generation of TaC can be increased, the oxygen vacancy concentration can be increased, and the conductivity of the lithium tantalate chip can be further improved.

[0017] As a preferred embodiment of the present invention, the inorganic carbon source includes flaky graphite and graphene; the mass ratio of the flaky graphite to the graphene is 1:(0.2~0.5). The flaky graphite and graphene are used as inorganic carbon sources. The graphene can effectively improve the reduction activity of the reducing agent, promote the reduction reaction, and improve the blackening degree of the chip. The flaky graphite and graphene form a uniform filling network structure in the system, uniformly reduce the lithium tantalate chip, and effectively improve the conductivity of the lithium tantalate chip.

[0018] As a preferred embodiment of the present invention, the average particle size of the flake graphite is 0.5-1 μm.

[0019] As a preferred embodiment of the present invention, the average particle size of the graphene is 10-14 μm, and the bulk density is 0.2-0.28 g / mL.

[0020] As a preferred embodiment of the present invention, the average particle size of the spherical zinc powder is 1-5 μm. By controlling the average particle size of the spherical zinc powder, it is possible to increase the reaction activity, reduce the reaction temperature, improve the reaction efficiency, and promote the formation of oxygen vacancies, thereby further improving the conductivity of the lithium tantalate wafer.

[0021] As a preferred embodiment of the present invention, the inert gas is nitrogen;

[0022] The reducing gas is a mixed gas of nitrogen and hydrogen, and the volume ratio of hydrogen to nitrogen is (2-10): (90-98).

[0023] As a preferred embodiment of the present invention, the carbonization temperature is 580-650° C. and the time is 2-5 hours.

[0024] As a preferred embodiment of the present invention, the heat treatment temperature is 850-880° C. and the time is 20-24 hours.

[0025] When the reducing agent is embedded in the surface of the lithium tantalate wafer, it is ensured that every surface of the lithium tantalate wafer is covered with the reducing agent.

[0026] As a preferred embodiment of the present invention, the thickness of the lithium tantalate wafer is 0.2-0.3 mm.

[0027] As a preferred embodiment of the present invention, the thickness of the reducing agent embedded on the upper surface of the lithium tantalate wafer is 1 to 5 mm.

[0028] As a preferred embodiment of the present invention, the thickness of the reducing agent embedded on the lower surface of the lithium tantalate wafer is 1 to 5 mm.

[0029] The present invention also provides a lithium tantalate wafer with high electrical conductivity, which is prepared by the above-mentioned preparation method.

[0030] The beneficial effect of the present invention is that the present invention uses an organic carbon source, an inorganic carbon source, and spherical zinc powder in a mass ratio of 1: (0.3-0.6): (0.4-0.7) as a reducing agent, embeds them on the surface of a lithium tantalate chip, first undergoes carbonization, and then undergoes heat treatment, which can effectively improve the conductivity of the lithium tantalate chip and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a diagram of the embedding of the reducing agent on the surface of lithium tantalate. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0033] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0034] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0035] In the present application, there is no particular limitation on the specific dispersion and stirring treatment methods.

[0036] Unless otherwise specified, the components, raw materials or instruments used in the embodiments and comparative examples of the present invention are all commercially available raw materials or instruments, and the components and raw materials used in each parallel experiment are all of the same kind.

[0037] Lithium tantalate chip: Sourced from Hunan Kexintai Electronics Co., Ltd.

[0038] Phenolic resin: from Jiangmen Kunyi Resin Material Technology Co., Ltd., with a softening point of 99~105℃, brand KT-3192F.

[0039] Sucrose: commonly available in the market.

[0040] Flake graphite-1: The average particle size is 0.5 μm, from Shanghai Xiangtian Nano, brand XT-C2-03.

[0041] Flake graphite-2: The average particle size is 1 μm, from Shanghai Xiangtian Nano, brand XT-C2-06.

[0042] Flake graphite-3: The average particle size is 0.1 μm, from Shanghai Xiangtian Nano, brand XT-C2-01.

[0043] Flake graphite-4: The average particle size is 5 μm, from Shanghai Xiangtian Nano, brand XT-C2-07.

[0044] Graphene-1: The average particle size is 10~14μm, the bulk density is 0.2~0.28g / mL, and it comes from Xiamen Kaina Graphene, brand KNG-180-3.

[0045] Graphene-2: The average particle size is 3~6μm, the bulk density is 0.15~0.2g / mL, and it comes from Xiamen Kaina Graphene, brand KNG-150-3.

[0046] Graphene-3: The average particle size is 20~45μm, the bulk density is 0.18~0.24g / mL, and it comes from Xiamen Kaina Graphene, brand KNG-182.

[0047] Spherical zinc powder-1: The average particle size is 1 μm, from Shanghai Xiangtian Nano, brand XT-Zn-04.

[0048] Spherical zinc powder-2: The average particle size is 5μm, from Shanghai Xiangtian Nano, brand XT-Zn-05.

[0049] Spherical zinc powder-3: The average particle size is 0.08μm, from Shanghai Xiangtian Nano, brand XT-Zn-03.

[0050] Spherical zinc powder-4: The average particle size is 10μm, from Shanghai Xiangtian Nano, brand XT-Zn-06.

[0051] The following examples are provided to facilitate understanding of the present invention. These examples are not provided to limit the scope of the claims.

[0052] Example 1

[0053] A method for preparing a lithium tantalate wafer with high electrical conductivity comprises the following steps:

[0054] (1) Cut a 6-inch lithium tantalate wafer (unprocessed lithium tantalate wafer, also known as lithium tantalate white wafer) into a square lithium tantalate wafer of 10*10*0.288 mm;

[0055] Provide a cylindrical crucible with a diameter of 15 mm;

[0056] (2) mixing an organic carbon source, an inorganic carbon source, and spherical zinc powder-1 in a mass ratio of 1:0.6:0.4 to obtain a reducing agent;

[0057] The organic carbon source includes sucrose and phenolic resin, and the mass ratio of the sucrose to the phenolic resin is 1:0.5. The inorganic carbon source includes at least one of flake graphite-1 and graphene-1, and the mass ratio of the flake graphite-1 to the graphene-1 is 1:0.6.

[0058] (3) If Figure 1As shown, a 3mm thick reducing agent is spread on the bottom of the cylindrical crucible 1 (corresponding to D1, 3mm in the figure), a lithium tantalate wafer 2 is placed, and then a 3mm thick reducing agent is spread on the surface of the lithium tantalate wafer (corresponding to Figure 1 D2 in the figure is 3 mm), so that the lithium tantalate wafer is fully covered with the reducing agent;

[0059] (4) placing the cylindrical crucible in a heat treatment furnace, introducing nitrogen at a flow rate of 0.5 L / min, heating the crucible to 650°C at a heating rate of 10°C / min, and carbonizing the crucible at 650°C for 4 h;

[0060] (5) Then, a reducing gas is introduced at a flow rate of 0.5 L / min, and the temperature is raised to 850° C. at a heating rate of 10° C. / min. Heat treatment is performed at 850° C. for 24 h, and the wafer is taken out to obtain a lithium tantalate wafer with high conductivity; the reducing gas is a mixed gas of nitrogen and hydrogen, and the volume ratio of the hydrogen to nitrogen is 5:95.

[0061] Example 2

[0062] A method for preparing a lithium tantalate wafer with high electrical conductivity comprises the following steps:

[0063] (1) Cut the 6-inch lithium tantalate wafer into a square lithium tantalate wafer of 10*10*0.288mm;

[0064] Provide a cylindrical crucible with a diameter of 15 mm;

[0065] (2) mixing an organic carbon source, an inorganic carbon source, and spherical zinc powder-1 in a mass ratio of 1:0.3:0.7 to obtain a reducing agent;

[0066] The organic carbon source includes sucrose and phenolic resin, and the mass ratio of the sucrose to the phenolic resin is 1:0.5. The inorganic carbon source includes at least one of flake graphite-1 and graphene-1, and the mass ratio of the flake graphite-1 to the graphene-1 is 1:0.6.

[0067] (3) If Figure 1 As shown, a 3mm thick reducing agent is spread on the bottom of the cylindrical crucible 1 (corresponding to D1, 3mm in the figure), a lithium tantalate wafer 2 is placed, and then a 3mm thick reducing agent is spread on the surface of the lithium tantalate wafer (corresponding to Figure 1 D2 in the figure is 3 mm), so that the lithium tantalate wafer is fully covered with the reducing agent;

[0068] (4) placing the cylindrical crucible in a heat treatment furnace, introducing nitrogen at a flow rate of 0.5 L / min, heating the crucible to 650°C at a heating rate of 10°C / min, and carbonizing the crucible at 650°C for 4 h;

[0069] (5) Then, a reducing gas is introduced at a flow rate of 0.5 L / min, and the temperature is raised to 850° C. at a heating rate of 10° C. / min. Heat treatment is performed at 850° C. for 24 h, and the wafer is taken out to obtain a lithium tantalate wafer with high conductivity; the reducing gas is a mixed gas of nitrogen and hydrogen, and the volume ratio of the hydrogen to nitrogen is 5:95.

[0070] Example 3

[0071] A method for preparing a lithium tantalate wafer with high electrical conductivity comprises the following steps:

[0072] (1) Cut the 6-inch lithium tantalate wafer into a square lithium tantalate wafer of 10*10*0.288mm;

[0073] Provide a cylindrical crucible with a diameter of 15 mm;

[0074] (2) mixing an organic carbon source, an inorganic carbon source, and spherical zinc powder-1 in a mass ratio of 1:0.6:0.4 to obtain a reducing agent;

[0075] The organic carbon source includes sucrose and phenolic resin, and the mass ratio of the sucrose to the phenolic resin is 1:2. The inorganic carbon source includes at least one of flake graphite-1 and graphene-1, and the mass ratio of the flake graphite-1 to the graphene-1 is 1:0.6.

[0076] (3) If Figure 1 As shown, a 3mm thick reducing agent is spread on the bottom of the cylindrical crucible 1 (corresponding to D1, 3mm in the figure), a lithium tantalate wafer 2 is placed, and then a 3mm thick reducing agent is spread on the surface of the lithium tantalate wafer (corresponding to Figure 1 D2 in the figure is 3 mm), so that the lithium tantalate wafer is fully covered with the reducing agent;

[0077] (4) placing the cylindrical crucible in a heat treatment furnace, introducing nitrogen at a flow rate of 0.5 L / min, heating the crucible to 650°C at a heating rate of 10°C / min, and carbonizing the crucible at 650°C for 4 h;

[0078] (5) Then, a reducing gas is introduced at a flow rate of 0.5 L / min, and the temperature is raised to 850° C. at a heating rate of 10° C. / min. Heat treatment is performed at 850° C. for 24 h, and the wafer is taken out to obtain a lithium tantalate wafer with high conductivity; the reducing gas is a mixed gas of nitrogen and hydrogen, and the volume ratio of the hydrogen to nitrogen is 5:95.

[0079] Example 4

[0080] A method for preparing a lithium tantalate wafer with high electrical conductivity comprises the following steps:

[0081] (1) Cut the 6-inch lithium tantalate wafer into a square lithium tantalate wafer of 10*10*0.288mm;

[0082] Provide a cylindrical crucible with a diameter of 15 mm;

[0083] (2) mixing an organic carbon source, an inorganic carbon source, and spherical zinc powder-1 in a mass ratio of 1:0.6:0.4 to obtain a reducing agent;

[0084] The organic carbon source includes sucrose and phenolic resin, and the mass ratio of the sucrose to the phenolic resin is 1:0.5. The inorganic carbon source includes at least one of flake graphite-1 and graphene-1, and the mass ratio of the flake graphite-1 to the graphene-1 is 1:0.2.

[0085] (3) If Figure 1 As shown, a 3mm thick reducing agent is spread on the bottom of the cylindrical crucible 1 (corresponding to D1, 3mm in the figure), a lithium tantalate wafer 2 is placed, and then a 3mm thick reducing agent is spread on the surface of the lithium tantalate wafer (corresponding to Figure 1 D2 in the figure is 3 mm), so that the lithium tantalate wafer is fully covered with the reducing agent;

[0086] (4) placing the cylindrical crucible in a heat treatment furnace, introducing nitrogen at a flow rate of 0.5 L / min, heating the crucible to 650°C at a heating rate of 10°C / min, and carbonizing the crucible at 650°C for 4 h;

[0087] (5) Then, a reducing gas is introduced at a flow rate of 0.5 L / min, and the temperature is raised to 850° C. at a heating rate of 10° C. / min. Heat treatment is performed at 850° C. for 24 h, and the wafer is taken out to obtain a lithium tantalate wafer with high conductivity; the reducing gas is a mixed gas of nitrogen and hydrogen, and the volume ratio of the hydrogen to nitrogen is 5:95.

[0088] Example 5

[0089] A method for preparing a lithium tantalate wafer with high electrical conductivity comprises the following steps:

[0090] (1) Cut the 6-inch lithium tantalate wafer into a square lithium tantalate wafer of 10*10*0.288mm;

[0091] Provide a cylindrical crucible with a diameter of 15 mm;

[0092] (2) mixing an organic carbon source, an inorganic carbon source, and spherical zinc powder-2 in a mass ratio of 1:0.6:0.4 to obtain a reducing agent;

[0093] The organic carbon source includes sucrose and phenolic resin, and the mass ratio of the sucrose to the phenolic resin is 1:0.5. The inorganic carbon source includes at least one of flake graphite-1 and graphene-1, and the mass ratio of the flake graphite-1 to the graphene-1 is 1:0.6.

[0094] (3) If Figure 1 As shown, a 3mm thick reducing agent is spread on the bottom of the cylindrical crucible 1 (corresponding to D1, 3mm in the figure), a lithium tantalate wafer 2 is placed, and then a 3mm thick reducing agent is spread on the surface of the lithium tantalate wafer (corresponding to Figure 1 D2 in the figure is 3 mm), so that the lithium tantalate wafer is fully covered with the reducing agent;

[0095] (4) placing the cylindrical crucible in a heat treatment furnace, introducing nitrogen at a flow rate of 0.5 L / min, heating the crucible to 650°C at a heating rate of 10°C / min, and carbonizing the crucible at 650°C for 4 h;

[0096] (5) Then, a reducing gas is introduced at a flow rate of 0.5 L / min, and the temperature is raised to 850° C. at a heating rate of 10° C. / min. Heat treatment is performed at 850° C. for 24 h, and the wafer is taken out to obtain a lithium tantalate wafer with high conductivity; the reducing gas is a mixed gas of nitrogen and hydrogen, and the volume ratio of the hydrogen to nitrogen is 5:95.

[0097] Example 6

[0098] A method for preparing a lithium tantalate wafer with high electrical conductivity comprises the following steps:

[0099] (1) Cut the 6-inch lithium tantalate wafer into a square lithium tantalate wafer of 10*10*0.288mm;

[0100] Provide a cylindrical crucible with a diameter of 15 mm;

[0101] (2) mixing an organic carbon source, an inorganic carbon source, and spherical zinc powder-3 in a mass ratio of 1:0.6:0.4 to obtain a reducing agent;

[0102] The organic carbon source includes sucrose and phenolic resin, and the mass ratio of the sucrose to the phenolic resin is 1:0.5. The inorganic carbon source includes at least one of flake graphite-1 and graphene-1, and the mass ratio of the flake graphite-1 to the graphene-1 is 1:0.6.

[0103] (3) If Figure 1 As shown, a 3mm thick reducing agent is spread on the bottom of the cylindrical crucible 1 (corresponding to D1, 3mm in the figure), a lithium tantalate wafer 2 is placed, and then a 3mm thick reducing agent is spread on the surface of the lithium tantalate wafer (corresponding to Figure 1 D2 in the figure is 3 mm), so that the lithium tantalate wafer is fully covered with the reducing agent;

[0104] (4) placing the cylindrical crucible in a heat treatment furnace, introducing nitrogen at a flow rate of 0.5 L / min, heating the crucible to 650°C at a heating rate of 10°C / min, and carbonizing the crucible at 650°C for 4 h;

[0105] (5) Then, a reducing gas is introduced at a flow rate of 0.5 L / min, and the temperature is raised to 850° C. at a heating rate of 10° C. / min. Heat treatment is performed at 850° C. for 24 h, and the wafer is taken out to obtain a lithium tantalate wafer with high conductivity; the reducing gas is a mixed gas of nitrogen and hydrogen, and the volume ratio of the hydrogen to nitrogen is 5:95.

[0106] Example 7

[0107] A method for preparing a lithium tantalate wafer with high electrical conductivity comprises the following steps:

[0108] (1) Cut the 6-inch lithium tantalate wafer into a square lithium tantalate wafer of 10*10*0.288mm;

[0109] Provide a cylindrical crucible with a diameter of 15 mm;

[0110] (2) mixing an organic carbon source, an inorganic carbon source, and spherical zinc powder-4 in a mass ratio of 1:0.6:0.4 to obtain a reducing agent;

[0111] The organic carbon source includes sucrose and phenolic resin, and the mass ratio of the sucrose to the phenolic resin is 1:0.5. The inorganic carbon source includes at least one of flake graphite-1 and graphene-1, and the mass ratio of the flake graphite-1 to the graphene-1 is 1:0.6.

[0112] (3) If Figure 1 As shown, a 3mm thick reducing agent is spread on the bottom of the cylindrical crucible 1 (corresponding to D1, 3mm in the figure), a lithium tantalate wafer 2 is placed, and then a 3mm thick reducing agent is spread on the surface of the lithium tantalate wafer (corresponding to Figure 1 D2 in the figure is 3 mm), so that the lithium tantalate wafer is fully covered with the reducing agent;

[0113] (4) placing the cylindrical crucible in a heat treatment furnace, introducing nitrogen at a flow rate of 0.5 L / min, heating the crucible to 650°C at a heating rate of 10°C / min, and carbonizing the crucible at 650°C for 4 h;

[0114] (5) Then, a reducing gas is introduced at a flow rate of 0.5 L / min, and the temperature is raised to 850° C. at a heating rate of 10° C. / min. Heat treatment is performed at 850° C. for 24 h, and the wafer is taken out to obtain a lithium tantalate wafer with high conductivity; the reducing gas is a mixed gas of nitrogen and hydrogen, and the volume ratio of the hydrogen to nitrogen is 5:95.

[0115] Example 8

[0116] A method for preparing a lithium tantalate wafer with high electrical conductivity comprises the following steps:

[0117] (1) Cut the 6-inch lithium tantalate wafer into a square lithium tantalate wafer of 10*10*0.288mm;

[0118] Provide a cylindrical crucible with a diameter of 15 mm;

[0119] (2) mixing an organic carbon source, an inorganic carbon source, and spherical zinc powder-1 in a mass ratio of 1:0.6:0.4 to obtain a reducing agent;

[0120] The organic carbon source includes sucrose and phenolic resin, and the mass ratio of the sucrose to the phenolic resin is 1:0.5. The inorganic carbon source includes at least one of flake graphite-2 and graphene-1, and the mass ratio of the flake graphite-1 to the graphene-1 is 1:0.6.

[0121] (3) If Figure 1 As shown, a 3mm thick reducing agent is spread on the bottom of the cylindrical crucible 1 (corresponding to D1, 3mm in the figure), a lithium tantalate wafer 2 is placed, and then a 3mm thick reducing agent is spread on the surface of the lithium tantalate wafer (corresponding to Figure 1 D2 in the figure is 3 mm), so that the lithium tantalate wafer is fully covered with the reducing agent;

[0122] (4) placing the cylindrical crucible in a heat treatment furnace, introducing nitrogen at a flow rate of 0.5 L / min, heating the crucible to 650°C at a heating rate of 10°C / min, and carbonizing the crucible at 650°C for 4 h;

[0123] (5) Then, a reducing gas is introduced at a flow rate of 0.5 L / min, and the temperature is raised to 850° C. at a heating rate of 10° C. / min. Heat treatment is performed at 850° C. for 24 h, and the wafer is taken out to obtain a lithium tantalate wafer with high conductivity; the reducing gas is a mixed gas of nitrogen and hydrogen, and the volume ratio of the hydrogen to nitrogen is 5:95.

[0124] Example 9

[0125] A method for preparing a lithium tantalate wafer with high electrical conductivity comprises the following steps:

[0126] (1) Cut the 6-inch lithium tantalate wafer into a square lithium tantalate wafer of 10*10*0.288mm;

[0127] Provide a cylindrical crucible with a diameter of 15 mm;

[0128] (2) mixing an organic carbon source, an inorganic carbon source, and spherical zinc powder-1 in a mass ratio of 1:0.6:0.4 to obtain a reducing agent;

[0129] The organic carbon source includes sucrose and phenolic resin, and the mass ratio of the sucrose to the phenolic resin is 1:0.5. The inorganic carbon source includes at least one of flake graphite-3 and graphene-1, and the mass ratio of the flake graphite-1 to the graphene-1 is 1:0.6.

[0130] (3) If Figure 1 As shown, a 3mm thick reducing agent is spread on the bottom of the cylindrical crucible 1 (corresponding to D1, 3mm in the figure), a lithium tantalate wafer 2 is placed, and then a 3mm thick reducing agent is spread on the surface of the lithium tantalate wafer (corresponding to Figure 1 D2 in the figure is 3 mm), so that the lithium tantalate wafer is fully covered with the reducing agent;

[0131] (4) placing the cylindrical crucible in a heat treatment furnace, introducing nitrogen at a flow rate of 0.5 L / min, heating the crucible to 650°C at a heating rate of 10°C / min, and carbonizing the crucible at 650°C for 4 h;

[0132] (5) Then, a reducing gas is introduced at a flow rate of 0.5 L / min, and the temperature is raised to 850° C. at a heating rate of 10° C. / min. Heat treatment is performed at 850° C. for 24 h, and the wafer is taken out to obtain a lithium tantalate wafer with high conductivity; the reducing gas is a mixed gas of nitrogen and hydrogen, and the volume ratio of the hydrogen to nitrogen is 5:95.

[0133] Example 10

[0134] A method for preparing a lithium tantalate wafer with high electrical conductivity comprises the following steps:

[0135] (1) Cut the 6-inch lithium tantalate wafer into a square lithium tantalate wafer of 10*10*0.288mm;

[0136] Provide a cylindrical crucible with a diameter of 15 mm;

[0137] (2) mixing an organic carbon source, an inorganic carbon source, and spherical zinc powder-1 in a mass ratio of 1:0.6:0.4 to obtain a reducing agent;

[0138] The organic carbon source includes sucrose and phenolic resin, and the mass ratio of the sucrose to the phenolic resin is 1:0.5. The inorganic carbon source includes at least one of flake graphite-4 and graphene-1, and the mass ratio of the flake graphite-1 to the graphene-1 is 1:0.6.

[0139] (3) If Figure 1 As shown, a 3mm thick reducing agent is spread on the bottom of the cylindrical crucible 1 (corresponding to D1, 3mm in the figure), a lithium tantalate wafer 2 is placed, and then a 3mm thick reducing agent is spread on the surface of the lithium tantalate wafer (corresponding to Figure 1 D2 in the figure is 3 mm), so that the lithium tantalate wafer is fully covered with the reducing agent;

[0140] (4) placing the cylindrical crucible in a heat treatment furnace, introducing nitrogen at a flow rate of 0.5 L / min, heating the crucible to 650°C at a heating rate of 10°C / min, and carbonizing the crucible at 650°C for 4 h;

[0141] (5) Then, a reducing gas is introduced at a flow rate of 0.5 L / min, and the temperature is raised to 850° C. at a heating rate of 10° C. / min. Heat treatment is performed at 850° C. for 24 h, and the wafer is taken out to obtain a lithium tantalate wafer with high conductivity; the reducing gas is a mixed gas of nitrogen and hydrogen, and the volume ratio of the hydrogen to nitrogen is 5:95.

[0142] Embodiment 11

[0143] A method for preparing a lithium tantalate wafer with high electrical conductivity comprises the following steps:

[0144] (1) Cut the 6-inch lithium tantalate wafer into a square lithium tantalate wafer of 10*10*0.288mm;

[0145] Provide a cylindrical crucible with a diameter of 15 mm;

[0146] (2) mixing an organic carbon source, an inorganic carbon source, and spherical zinc powder-1 in a mass ratio of 1:0.6:0.4 to obtain a reducing agent;

[0147] The organic carbon source includes sucrose and phenolic resin, and the mass ratio of the sucrose to the phenolic resin is 1:0.5. The inorganic carbon source includes at least one of flake graphite-1 and graphene-2, and the mass ratio of the flake graphite-1 to the graphene-1 is 1:0.6.

[0148] (3) If Figure 1 As shown, a 3mm thick reducing agent is spread on the bottom of the cylindrical crucible 1 (corresponding to D1, 3mm in the figure), a lithium tantalate wafer 2 is placed, and then a 3mm thick reducing agent is spread on the surface of the lithium tantalate wafer (corresponding to Figure 1 D2 in the figure is 3 mm), so that the lithium tantalate wafer is fully covered with the reducing agent;

[0149] (4) placing the cylindrical crucible in a heat treatment furnace, introducing nitrogen at a flow rate of 0.5 L / min, heating the crucible to 650°C at a heating rate of 10°C / min, and carbonizing the crucible at 650°C for 4 h;

[0150] (5) Then, a reducing gas is introduced at a flow rate of 0.5 L / min, and the temperature is raised to 850° C. at a heating rate of 10° C. / min. Heat treatment is performed at 850° C. for 24 h, and the wafer is taken out to obtain a lithium tantalate wafer with high conductivity; the reducing gas is a mixed gas of nitrogen and hydrogen, and the volume ratio of the hydrogen to nitrogen is 5:95.

[0151] Example 12

[0152] A method for preparing a lithium tantalate wafer with high electrical conductivity comprises the following steps:

[0153] (1) Cut the 6-inch lithium tantalate wafer into a square lithium tantalate wafer of 10*10*0.288mm;

[0154] Provide a cylindrical crucible with a diameter of 15 mm;

[0155] (2) mixing an organic carbon source, an inorganic carbon source, and spherical zinc powder-1 in a mass ratio of 1:0.6:0.4 to obtain a reducing agent;

[0156] The organic carbon source includes sucrose and phenolic resin, and the mass ratio of the sucrose to the phenolic resin is 1:0.5. The inorganic carbon source includes at least one of flake graphite-1 and graphene-3, and the mass ratio of the flake graphite-1 to graphene-1 is 1:0.6.

[0157] (3) If Figure 1 As shown, a 3mm thick reducing agent is spread on the bottom of the cylindrical crucible 1 (corresponding to D1, 3mm in the figure), a lithium tantalate wafer 2 is placed, and then a 3mm thick reducing agent is spread on the surface of the lithium tantalate wafer (corresponding to Figure 1 D2 in the figure is 3 mm), so that the lithium tantalate wafer is fully covered with the reducing agent;

[0158] (4) placing the cylindrical crucible in a heat treatment furnace, introducing nitrogen at a flow rate of 0.5 L / min, heating the crucible to 650°C at a heating rate of 10°C / min, and carbonizing the crucible at 650°C for 4 h;

[0159] (5) Then, a reducing gas is introduced at a flow rate of 0.5 L / min, and the temperature is raised to 850° C. at a heating rate of 10° C. / min. Heat treatment is performed at 850° C. for 24 h, and the wafer is taken out to obtain a lithium tantalate wafer with high conductivity; the reducing gas is a mixed gas of nitrogen and hydrogen, and the volume ratio of the hydrogen to nitrogen is 5:95.

[0160] Example 13

[0161] A method for preparing a lithium tantalate wafer with high electrical conductivity comprises the following steps:

[0162] (1) Cut the 6-inch lithium tantalate wafer into a square lithium tantalate wafer of 10*10*0.288mm;

[0163] Provide a cylindrical crucible with a diameter of 15 mm;

[0164] (2) mixing an organic carbon source, an inorganic carbon source, and spherical zinc powder-1 in a mass ratio of 1:0.6:0.4 to obtain a reducing agent;

[0165] The organic carbon source includes sucrose and phenolic resin, and the mass ratio of the sucrose to the phenolic resin is 1:0.5. The inorganic carbon source includes at least one of flake graphite-1 and graphene-1, and the mass ratio of the flake graphite-1 to the graphene-1 is 1:0.6.

[0166] (3) If Figure 1 As shown, a 3mm thick reducing agent is spread on the bottom of the cylindrical crucible 1 (corresponding to D1, 3mm in the figure), a lithium tantalate wafer 2 is placed, and then a 3mm thick reducing agent is spread on the surface of the lithium tantalate wafer (corresponding to Figure 1 D2 in the figure is 3 mm), so that the lithium tantalate wafer is fully covered with the reducing agent;

[0167] (4) placing the cylindrical crucible in a heat treatment furnace, introducing nitrogen at a flow rate of 0.5 L / min, heating the crucible to 650°C at a heating rate of 10°C / min, and carbonizing the crucible at 650°C for 4 h;

[0168] (5) Then, a reducing gas is introduced at a flow rate of 0.5 L / min, and the temperature is raised to 880° C. at a heating rate of 10° C. / min. Heat treatment is performed at 880° C. for 24 h, and the wafer is taken out to obtain a lithium tantalate wafer with high conductivity; the reducing gas is a mixed gas of nitrogen and hydrogen, and the volume ratio of the hydrogen to nitrogen is 5:95.

[0169] Embodiment 14

[0170] A method for preparing a lithium tantalate wafer with high electrical conductivity comprises the following steps:

[0171] (1) Cut the 6-inch lithium tantalate wafer into a square lithium tantalate wafer of 10*10*0.288mm;

[0172] Provide a cylindrical crucible with a diameter of 15 mm;

[0173] (2) mixing an organic carbon source, an inorganic carbon source, and spherical zinc powder-1 in a mass ratio of 1:0.6:0.4 to obtain a reducing agent;

[0174] The organic carbon source is sucrose. The inorganic carbon source includes at least one of flake graphite-1 and graphene-1; the mass ratio of flake graphite-1 to graphene-1 is 1:0.6.

[0175] (3) If Figure 1 As shown, a 3mm thick reducing agent is spread on the bottom of the cylindrical crucible 1 (corresponding to D1, 3mm in the figure), a lithium tantalate wafer 2 is placed, and then a 3mm thick reducing agent is spread on the surface of the lithium tantalate wafer (corresponding to Figure 1 D2 in the figure is 3 mm), so that the lithium tantalate wafer is fully covered with the reducing agent;

[0176] (4) placing the cylindrical crucible in a heat treatment furnace, introducing nitrogen at a flow rate of 0.5 L / min, heating the crucible to 650°C at a heating rate of 10°C / min, and carbonizing the crucible at 650°C for 4 h;

[0177] (5) Then, a reducing gas is introduced at a flow rate of 0.5 L / min, and the temperature is raised to 850° C. at a heating rate of 10° C. / min. Heat treatment is performed at 850° C. for 24 h, and the wafer is taken out to obtain a lithium tantalate wafer with high conductivity; the reducing gas is a mixed gas of nitrogen and hydrogen, and the volume ratio of the hydrogen to nitrogen is 5:95.

[0178] Embodiment 15

[0179] A method for preparing a lithium tantalate wafer with high electrical conductivity comprises the following steps:

[0180] (1) Cut the 6-inch lithium tantalate wafer into a square lithium tantalate wafer of 10*10*0.288mm;

[0181] Provide a cylindrical crucible with a diameter of 15 mm;

[0182] (2) mixing an organic carbon source, an inorganic carbon source, and spherical zinc powder-1 in a mass ratio of 1:0.6:0.4 to obtain a reducing agent;

[0183] The organic carbon source is phenolic resin. The inorganic carbon source includes at least one of flake graphite-1 and graphene-1; the mass ratio of flake graphite-1 to graphene-1 is 1:0.6.

[0184] (3) If Figure 1 As shown, a 3mm thick reducing agent is spread on the bottom of the cylindrical crucible 1 (corresponding to D1, 3mm in the figure), a lithium tantalate wafer 2 is placed, and then a 3mm thick reducing agent is spread on the surface of the lithium tantalate wafer (corresponding to Figure 1 D2 in the figure is 3 mm), so that the lithium tantalate wafer is fully covered with the reducing agent;

[0185] (4) placing the cylindrical crucible in a heat treatment furnace, introducing nitrogen at a flow rate of 0.5 L / min, heating the crucible to 650°C at a heating rate of 10°C / min, and carbonizing the crucible at 650°C for 4 h;

[0186] (5) Then, a reducing gas is introduced at a flow rate of 0.5 L / min, and the temperature is raised to 850° C. at a heating rate of 10° C. / min. Heat treatment is performed at 850° C. for 24 h, and the wafer is taken out to obtain a lithium tantalate wafer with high conductivity; the reducing gas is a mixed gas of nitrogen and hydrogen, and the volume ratio of the hydrogen to nitrogen is 5:95.

[0187] Example 16

[0188] A method for preparing a lithium tantalate wafer with high electrical conductivity comprises the following steps:

[0189] (1) Cut the 6-inch lithium tantalate wafer into a square lithium tantalate wafer of 10*10*0.288mm;

[0190] Provide a cylindrical crucible with a diameter of 15 mm;

[0191] (2) mixing an organic carbon source, an inorganic carbon source, and spherical zinc powder-1 in a mass ratio of 1:0.6:0.4 to obtain a reducing agent;

[0192] The organic carbon source includes sucrose and phenolic resin, and the mass ratio of the sucrose to the phenolic resin is 1:0.5. The inorganic carbon source is flake graphite-1.

[0193] (3) If Figure 1 As shown, a 3mm thick reducing agent is spread on the bottom of the cylindrical crucible 1 (corresponding to D1, 3mm in the figure), a lithium tantalate wafer 2 is placed, and then a 3mm thick reducing agent is spread on the surface of the lithium tantalate wafer (corresponding to Figure 1 D2 in the figure is 3 mm), so that the lithium tantalate wafer is fully covered with the reducing agent;

[0194] (4) placing the cylindrical crucible in a heat treatment furnace, introducing nitrogen at a flow rate of 0.5 L / min, heating the crucible to 650°C at a heating rate of 10°C / min, and carbonizing the crucible at 650°C for 4 h;

[0195] (5) Then, a reducing gas is introduced at a flow rate of 0.5 L / min, and the temperature is raised to 850° C. at a heating rate of 10° C. / min. Heat treatment is performed at 850° C. for 24 h, and the wafer is taken out to obtain a lithium tantalate wafer with high conductivity; the reducing gas is a mixed gas of nitrogen and hydrogen, and the volume ratio of the hydrogen to nitrogen is 5:95.

[0196] Embodiment 17

[0197] A method for preparing a lithium tantalate wafer with high electrical conductivity comprises the following steps:

[0198] (1) Cut the 6-inch lithium tantalate wafer into a square lithium tantalate wafer of 10*10*0.288mm;

[0199] Provide a cylindrical crucible with a diameter of 15 mm;

[0200] (2) mixing an organic carbon source, an inorganic carbon source, and spherical zinc powder-1 in a mass ratio of 1:0.6:0.4 to obtain a reducing agent;

[0201] The organic carbon source includes sucrose and phenolic resin, and the mass ratio of the sucrose to the phenolic resin is 1:0.5. The inorganic carbon source is graphene-1.

[0202] (3) If Figure 1 As shown, a 3mm thick reducing agent is spread on the bottom of the cylindrical crucible 1 (corresponding to D1, 3mm in the figure), a lithium tantalate wafer 2 is placed, and then a 3mm thick reducing agent is spread on the surface of the lithium tantalate wafer (corresponding to Figure 1 D2 in the figure is 3 mm), so that the lithium tantalate wafer is fully covered with the reducing agent;

[0203] (4) placing the cylindrical crucible in a heat treatment furnace, introducing nitrogen at a flow rate of 0.5 L / min, heating the crucible to 650°C at a heating rate of 10°C / min, and carbonizing the crucible at 650°C for 4 h;

[0204] (5) Then, a reducing gas is introduced at a flow rate of 0.5 L / min, and the temperature is raised to 850° C. at a heating rate of 10° C. / min. Heat treatment is performed at 850° C. for 24 h, and the wafer is taken out to obtain a lithium tantalate wafer with high conductivity; the reducing gas is a mixed gas of nitrogen and hydrogen, and the volume ratio of the hydrogen to nitrogen is 5:95.

[0205] Comparative Example 1

[0206] The difference between Comparative Example 1 and Example 1 is that the reducing agent of Comparative Example 1 does not contain an organic carbon source, and the other aspects are the same.

[0207] In this comparative example, an inorganic carbon source and spherical zinc powder-1 were uniformly mixed in a mass ratio of 0.6:0.4 to obtain a reducing agent.

[0208] Comparative Example 2

[0209] The difference between Comparative Example 2 and Example 1 is that the reducing agent of Comparative Example 2 does not contain an inorganic carbon source, and the other aspects are the same.

[0210] In this comparative example, an organic carbon source and spherical zinc powder-1 were uniformly mixed in a mass ratio of 1:0.4 to obtain a reducing agent.

[0211] Comparative Example 3

[0212] The difference between Comparative Example 3 and Example 1 is that the reducing agent of Comparative Example 3 does not contain spherical zinc powder, and the other aspects are the same.

[0213] In this comparative example, an organic carbon source and an inorganic carbon source were uniformly mixed in a mass ratio of 1:0.6 to obtain a reducing agent.

[0214] Comparative Example 4

[0215] The difference between Comparative Example 4 and Example 1 is that the reducing agent in Comparative Example 4 is a single organic carbon source, and the others are the same.

[0216] Comparative Example 5

[0217] The difference between Comparative Example 5 and Example 1 is that the reducing agent in Comparative Example 5 is a single inorganic carbon source, and the others are the same.

[0218] Comparative Example 6

[0219] The difference between Comparative Example 6 and Example 1 is that the reducing agent in Comparative Example 6 is a single spherical zinc powder-1, and the other parts are the same.

[0220] Comparative Example 7

[0221] The difference between Comparative Example 7 and Example 1 is that the mass ratio of the organic carbon source, the inorganic carbon source, and the spherical zinc powder-1 in Comparative Example 7 is not within the scope of the present invention, and the others are the same.

[0222] The organic carbon source, the inorganic carbon source and the spherical zinc powder-1 are uniformly mixed in a mass ratio of 1:0.1:0.9 to obtain a reducing agent.

[0223] Comparative Example 8

[0224] The difference between Comparative Example 8 and Example 1 is that the mass ratio of the organic carbon source, the inorganic carbon source, and the spherical zinc powder-1 in Comparative Example 8 is not within the scope of the present invention, and the others are the same.

[0225] The organic carbon source, the inorganic carbon source and the spherical zinc powder-1 are uniformly mixed in a mass ratio of 1:0.9:0.1 to obtain a reducing agent.

[0226] Comparative Example 9

[0227] The difference between Comparative Example 9 and Example 1 is that the temperature of the heat treatment in step (5) of Comparative Example 9 is 700°C.

[0228] Comparative Example 10

[0229] The difference between Comparative Example 10 and Example 1 is that the temperature of the heat treatment in step (5) of Comparative Example 10 is 1000°C.

[0230] Test Case

[0231] The ST2643 ultra-high resistance micro-current tester (high resistance volume resistivity surface resistivity tester) uses the principle of the ring three-electrode method. The volume resistivity of the lithium tantalate wafer after electro-blackening is obtained, where ρ is the volume resistivity (Ω·cm), L is the wafer thickness, S is the contact area, and R is the volume resistance value of the lithium tantalate wafer after blackening. Apply a voltage source Vs to the upper electrode, specify the current flowing through the blackened lithium tantalate sample to be Im, and then the volume resistance R can be calculated using the formula Find R.

[0232] Table 1

[0233]

[0234] It can be seen from Table 1 that the method described in the present invention can prepare lithium tantalate wafers with high electrical conductivity. The method of the present invention significantly improves the electrical conductivity of the lithium tantalate wafer, and has broad application prospects.

[0235] By comparing Example 1 with Comparative Examples 1 to 6, it can be seen that the organic carbon source, inorganic carbon source and spherical zinc powder described in the present invention can significantly improve the conductivity of the lithium tantalate wafer, and the organic carbon source, inorganic carbon source and spherical zinc powder have a significant synergistic effect in improving the conductivity of lithium tantalate. The lack of any one of them will lead to a significant decrease in conductivity.

[0236] By comparing Example 1 with Comparative Examples 7-8, it can be seen that by controlling the mass ratio of the organic carbon source, the inorganic carbon source and the spherical zinc powder within the range of the present invention, the conductivity of the lithium tantalate wafer can be more significantly improved.

[0237] By comparing Example 1 with Comparative Examples 9-10, it can be seen that by controlling the temperature of the heat treatment to 850-880° C., the conductivity of the lithium tantalate wafer can be more significantly improved.

[0238] By comparing Example 1 with Examples 5 to 7, it can be seen that by controlling the average particle size of the spherical zinc powder to be 1 to 5 μm, the conductivity of the lithium tantalate wafer can be further improved.

[0239] By comparing Example 1 with Examples 8 to 10, it can be seen that by controlling the average particle size of the flake graphite to be 0.5 to 1 μm, the conductivity of the lithium tantalate wafer can be further improved.

[0240] By comparing Example 1 with Examples 11-12, it can be seen that by controlling the average particle size of the graphene to be 10-14 μm and the packing density to be 0.2-0.28 g / mL, the conductivity of the lithium tantalate wafer can be further improved.

[0241] By comparing Example 1 with Examples 14-15, it can be seen that by using sucrose and phenolic resin as organic carbon sources, the conductivity of the lithium tantalate wafer can be further improved.

[0242] By comparing Example 1 with Examples 16 to 17, it can be seen that the conductivity of the lithium tantalate wafer can be further improved by using flake graphite and graphene as inorganic carbon sources.

[0243] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a high-conductivity lithium tantalate wafer, characterized in that: The following steps are involved: The organic carbon source, the inorganic carbon source and the spherical zinc powder are mixed uniformly to obtain a reducing agent; The reducing agent is embedded in the surface of the lithium tantalate wafer, placed in a heat treatment furnace, and an inert gas is introduced for carbonization; a reducing gas is then introduced for heat treatment, and the wafer is taken out to obtain a lithium tantalate wafer with high conductivity; The organic carbon source includes sucrose and phenolic resin, and the mass ratio of the sucrose to the phenolic resin is 1: (0.5-2); the inorganic carbon source includes flake graphite and graphene, and the mass ratio of the flake graphite to the graphene is 1: (0.2-0.5); The mass ratio of the organic carbon source, the inorganic carbon source and the spherical zinc powder is 1: (0.3-0.6): (0.4-0.7); The carbonization temperature is 580-650°C and the time is 2-5h; The heat treatment temperature is 850-880°C and the time is 20-24h.

2. The method for preparing a high-conductivity lithium tantalate wafer according to claim 1, characterized in that: The average particle size of the flake graphite is 0.5-1 μm.

3. The method for preparing a high-conductivity lithium tantalate wafer according to claim 1, characterized in that: The average particle size of the graphene is 10-14 μm, and the bulk density is 0.2-0.28 g / mL.

4. The method for preparing a high-conductivity lithium tantalate wafer according to claim 1, characterized in that: The average particle size of the spherical zinc powder is 1-5 μm.

5. The method for preparing a high-conductivity lithium tantalate wafer according to claim 1, characterized in that: The inert gas is nitrogen; The reducing gas is a mixed gas of nitrogen and hydrogen, and the volume ratio of hydrogen to nitrogen is (2-10): (90-98).

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