A Nb-doped tantalum tin oxide target and its preparation method
By preparing Nb-doped tantalum tin oxide targets, the high-temperature stability and cost issues of ITO transparent conductive films were solved, realizing high-density, low-resistivity targets and expanding their applications in multiple fields.
Patent Information
- Application Number
- CN202311250365.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-26
- Publication Date
- 2025-10-28
- Estimated Expiration
- 2043-09-26
AI Technical Summary
Existing tin-doped indium oxide (ITO) transparent conductive films suffer from poor stability at high temperatures, high cost, insufficient mechanical properties and chemical durability, and indium's biological toxicity limits their application range.
Nb-doped tantalum-tin oxide target materials were prepared by mixing tin oxide, tantalum oxide and niobium oxide powders, followed by sand milling and spray granulation. The target materials were then subjected to cold pressing, cold isostatic pressing and degreasing sintering treatments, and the process conditions were controlled to obtain high-density and low-resistivity target materials.
A Nb-doped tantalum-containing tin oxide target with uniform grains, low bulk resistivity, and high density was prepared. It has good high-temperature stability and low cost, and is suitable for a variety of transparent conductive thin film applications.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of target manufacturing technology, and particularly relates to a tantalum tin oxide target doped with Nb and its preparation method. Background Technology
[0002] Transparent conductive films made of metal oxides have high transmittance (>85%) and low resistivity (up to 10 ohms) for visible light. -3 -10 -4 Indium tin oxide (ITO) films possess excellent optoelectronic properties, leading to their widespread application in flat panel displays, solar cells, transparent electromagnetic shielding and antistatic devices, resistive touchscreens, and biosensors. Among these, the most widely used transparent conductive film is ITO film. Despite its broad application, ITO transparent conductive films suffer from several drawbacks, including complex fabrication processes, poor high-temperature stability (indium diffusion at higher temperatures affects device performance), and high cost (indium is a precious metal with limited natural reserves). Furthermore, the relatively poor mechanical and chemical durability of the films, coupled with the biotoxicity of indium and its compounds, significantly limits their application scope. Summary of the Invention
[0003] One of the objectives of this invention is to provide a method for preparing Nb-doped tantalum tin oxide targets. This method can obtain Nb-doped tantalum tin oxide targets (i.e., TTO targets) with uniform grain size, low bulk resistivity, and high density. The process is simple, has good high-temperature stability, and is low in cost.
[0004] The second objective of this invention is to provide a tantalum-containing tin oxide target doped with Nb.
[0005] To achieve one of the above objectives, the present invention employs the following technical solution:
[0006] A method for preparing an Nb-doped tantalum tin oxide target, the method comprising the following steps:
[0007] Step S1: Mix tin oxide powder, tantalum oxide powder and niobium oxide powder evenly in water to obtain a slurry with a solid content of 40-80%.
[0008] Step S2: After adding the polyvinyl carboxylic acid dispersant to the slurry, stir for 25-35 minutes, then sand mill, then add the polyvinyl alcohol binder, disperse for 25-35 minutes, and then spray granulate to make powder.
[0009] The mass ratio of the polyvinyl carboxylic acid dispersant, polyvinyl alcohol binder, and slurry is 0.05–2:0.5–4:100;
[0010] The grinding speed in the aforementioned grinding process is 1000–2000 rpm, and the grinding time is 0.5–2 hours.
[0011] The drying speed of the spray granulation is 10,000 to 30,000 rpm, and the drying temperature is 80 to 120°C.
[0012] Step S3: The powder obtained in step S2 is cold-pressed under a pressure of 100-200 MPa to obtain a cold-pressed blank.
[0013] Step S4: The cold-pressed preform is cold isostatically pressed under a pressure of 200-350 MPa to obtain a cold isostatically pressed preform.
[0014] Step S5: The cold isostatic pressed blank is subjected to degreasing sintering and surface processing in sequence to obtain tantalum tin oxide target material.
[0015] Furthermore, in step S1, the tin, tantalum, and niobium in the tin oxide powder, tantalum oxide powder, and niobium oxide powder satisfy the following condition in atomic ratio:
[0016] Ta / (Sn+Ta) = 0.75~7.0%;
[0017] Nb / (Ta+Nb) = 3.5–26.7%.
[0018] Furthermore, in step S1, the purity of the tin oxide powder is not less than 99.99%, and the particle size is 0.1-10 μm;
[0019] The tantalum oxide powder has a purity of not less than 99.99% and a particle size of 0.1–30 μm;
[0020] The purity of the niobium oxide powder is not less than 99.99%, and the particle size is 0.1-5 μm.
[0021] Furthermore, in step S1, the solid content of the slurry is 50-70%.
[0022] Furthermore, in step S2, the mass ratio of the polyvinyl carboxylic acid dispersant, polyvinyl alcohol binder, and slurry is 0.5–1:1–3:100;
[0023] The grinding speed in the aforementioned grinding process is 1200–1700 rpm, and the grinding time is 1–1.5 h.
[0024] The drying speed of the spray granulation is 17,000 to 23,000 rpm, and the drying temperature is 90 to 100°C.
[0025] Furthermore, in step S3, the pressure of the cold pressing is 130-170 MPa.
[0026] Furthermore, in step S4, the pressure of the cold isostatic pressing is 240-330 MPa.
[0027] Furthermore, in step S5, the degreasing and sintering process is as follows: The temperature is increased to 520–690°C at a heating rate of 0.2–0.7°C / min, and held for 12–38 hours before degreasing to remove water and additives (such as polyvinyl carboxylic acid dispersant and polyvinyl alcohol binder) from the green blank, while ensuring that the green blank does not deform or crack; then, the temperature is increased to 1420–1580°C at a heating rate of 1–5°C / min, and held for 6–18 hours before sintering to ensure that Ta2O5 reacts with SnO2 to generate a second phase with excellent electrical conductivity, and that Nb2O5 promotes the shrinkage and densification of the green blank during sintering, thereby improving electrical conductivity; finally, the green blank is cooled to room temperature with the furnace.
[0028] To achieve the second objective mentioned above, the present invention employs the following technical solution:
[0029] A tantalum-containing tin oxide target doped with Nb, wherein the tantalum-containing tin oxide target is prepared by the preparation method described above.
[0030] Furthermore, the tantalum-containing tin oxide target has a relative density ≥96% and a resistivity ≤5×10⁻⁶. -2 Ω·cm, bending strength ≥220Mpa.
[0031] In summary, the beneficial effects of this invention are as follows:
[0032] This invention prepares a slurry with a solid content of 40-80% using tin oxide powder, tantalum oxide powder, niobium oxide powder, and water. The powder, obtained through sand milling and spray granulation, is then subjected to cold pressing, cold isostatic pressing, debinding and sintering, and surface finishing treatments. By controlling the process conditions for cold pressing, cold isostatic pressing, debinding, and sintering, a Nb-doped tantalum tin oxide target (i.e., TTO target) with uniform grain size, low bulk resistivity, and high density is obtained. The process is simple, exhibits good high-temperature stability, and is low in cost. The Nb-doped tantalum tin oxide target of this invention has a relative density ≥96% and a resistivity ≤5×10⁻⁶. -2 With a resistivity of Ω·cm, a bending strength ≥220 MPa, and uniform microstructure, this film exhibits excellent coating performance. Using the Nb-doped tantalum-containing tin oxide target of this invention, a transparent conductive film with low resistivity, high transmittance, and uniform thickness can be obtained. This transparent conductive film possesses good electrical properties, optical properties, chemical durability, and thermal stability. The tantalum-doped tin oxide film prepared using the Nb-doped tantalum-containing tin oxide target of this invention can be used not only in flat panel displays, solar cells, transparent electromagnetic shielding, and antistatic devices, but also in resistive touchscreens and biosensors where special requirements exist for film toxicity and biocompatibility. Detailed Implementation
[0033] Example 1:
[0034] 1) Take 940g of 99.99% pure material with a particle size of D 90 Tin oxide with a particle size of 1.2 μm, 50 g, 99.99% purity, particle size D 90 Tantalum oxide with a particle size of 15 μm, 10 g of 99.99% purity, particle size D 90 Niobium oxide powder of 1.5 μm and 600 g of water were uniformly mixed to form a slurry. 8 g of polyvinyl carboxylic acid dispersant was added and stirred for 30 min. The mixture was then ground in a sand mill at 1200 rpm for 30 min. 16 g of polyvinyl alcohol binder was then added and the mixture was dispersed for another 30 min. The mixture was then dried into powder using a spray granulator at 100℃ and atomization speed of 17000 rpm.
[0035] 2) The powder obtained by atomization is cold-pressed to form a target material with a pressing pressure of 130 MPa and a holding pressure of 3 min; then it is placed in an isostatic pressing device for cold isostatic pressing densification with a pressure of 240 MPa and a holding pressure of 10 min to obtain a raw target material.
[0036] 3) The green blank is placed in a sintering furnace for degreasing and sintering. The temperature is increased to 600℃ at 0.5℃ / min and held for 20h for degreasing. Then the temperature is increased to 1550℃ at 3℃ / min and held for 10h for sintering. After sintering, the blank is cooled to room temperature with the furnace and then surface treated to obtain Nb-doped TTO target material.
[0037] The Nb-doped TTO target in this embodiment has a relative density of 97.0%, a flexural strength of 230 MPa, and a resistivity of 2.1 × 10⁻⁶. -2 Ω·cm.
[0038] Example 2:
[0039] 1) Take 940g of 99.99% pure material with a particle size of D 90 Tin oxide with a particle size of 2.5 μm, 50 g, 99.99% purity, particle size D 90 Tantalum oxide with a particle size of 7.5 μm, 10g with a purity of 99.99%, particle size D 90 Niobium oxide powder of 2.1 μm and 1500 g of water were mixed evenly to form a slurry. 1.25 g of polyvinyl carboxylic acid dispersant was added and stirred for 35 min. The mixture was then ground in a sand mill at 2000 rpm for 2 h. 12.5 g of polyvinyl alcohol binder was then added and the mixture was dispersed for another 35 min. The mixture was then dried into powder using a spray granulator at 120℃ and an atomization speed of 30000 rpm.
[0040] 2) The powder obtained by atomization is cold-pressed to form a target material with a pressing pressure of 200 MPa and a holding pressure of 5 min; then it is placed in an isostatic pressing device for cold isostatic pressing densification with a pressure of 350 MPa and a holding pressure of 15 min to obtain a raw target material.
[0041] 3) The green blank is placed in a sintering furnace for degreasing and sintering. The temperature is increased to 520℃ at 0.2℃ / min and held for 38h for degreasing. Then the temperature is increased to 1580℃ at 5℃ / min and held for 18h for sintering. After sintering, the blank is cooled to room temperature with the furnace and then surface treated to obtain Nb-doped TTO target material.
[0042] The Nb-doped TTO target in this embodiment has a relative density of 98%, a flexural strength of 240 MPa, and a resistivity of 8.2 × 10⁻⁶. -3 Ω·cm.
[0043] Example 3:
[0044] 1) Take 900g of 99.99% pure material with a particle size of D 90 Tin oxide with a particle size of 1.2 μm, 90 g, 99.99% purity, particle size D 90 Tantalum oxide with a particle size of 15 μm, 10 g of 99.99% purity, particle size D 90 Niobium oxide powder of 1.5 μm and 250 g of water were uniformly mixed to form a slurry. 25 g of polyvinyl carboxylic acid dispersant was added and stirred for 25 min. The mixture was then ground in a sand mill at a speed of 1700 rpm for 1 h. 50 g of polyvinyl alcohol binder was then added and the mixture was dispersed for another 25 min. The mixture was then dried into powder using a spray granulator at a drying temperature of 90℃ and an atomization speed of 23000 rpm.
[0045] 2) The powder obtained by atomization is cold-pressed to form a target material with a pressing pressure of 100 MPa and a holding pressure of 1 min; then it is placed in an isostatic pressing device for cold isostatic pressing densification with a pressure of 330 MPa and a holding pressure of 5 min to obtain a raw target material.
[0046] 3) The green blank is placed in a sintering furnace for degreasing and sintering. The temperature is increased to 690℃ at 0.7℃ / min and held for 12h for degreasing. Then the temperature is increased to 1420℃ at 1℃ / min and held for 6h for sintering. After sintering, the blank is cooled to room temperature with the furnace and then surface treated to obtain Nb-doped TTO target material.
[0047] The Nb-doped TTO target in this embodiment has a relative density of 96%, a flexural strength of 220 MPa, and a resistivity of 5.0 × 10⁻⁶. -2 Ω·cm.
[0048] Example 4:
[0049] 1) Take 900g of 99.99% pure material with a particle size of D 90 Tin oxide with a particle size of 2.5 μm, 90 g, 99.99% purity, particle size D 90 Tantalum oxide with a particle size of 7.5 μm, 10g with a purity of 99.99%, particle size D 90 Niobium oxide powder of 2.1 μm and 1000 g of water were mixed evenly to form a slurry. 20 g of polyvinyl carboxylic acid dispersant was added and stirred for 28 min. The mixture was then ground in a sand mill at 1000 rpm for 1.5 h. 60 g of polyvinyl alcohol binder was then added and the mixture was dispersed for another 27 min. The mixture was then dried into powder using a spray granulator at 80 °C and atomization speed of 10000 rpm.
[0050] 2) The powder obtained by atomization is cold-pressed to form a target material with a pressing pressure of 170 MPa and a holding pressure of 2 min; then it is placed in an isostatic pressing device for cold isostatic pressing densification with a pressure of 200 MPa and a holding pressure of 8 min to obtain a raw target material.
[0051] 3) The green blank is placed in a sintering furnace for degreasing and sintering. The temperature is increased to 630℃ at 0.6℃ / min and held for 20h for degreasing. Then the temperature is increased to 1510℃ at 4℃ / min and held for 16h for sintering. After sintering, the blank is cooled to room temperature with the furnace and then surface treated to obtain Nb-doped TTO target material.
[0052] The Nb-doped TTO target in this embodiment has a relative density of 96.5%, a flexural strength of 227 MPa, and a resistivity of 3.5 × 10⁻⁶. -2 Ω·cm.
[0053] Please note that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The above embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.
Claims
1. A method for preparing an Nb-doped tantalum-containing tin oxide target, characterized in that, The method for preparing the tantalum-containing tin oxide target material includes the following steps: Step S1: Mix tin oxide powder, tantalum oxide powder and niobium oxide powder evenly in water to obtain a slurry with a solid content of 40-80%. In step S1, the tin, tantalum, and niobium in the tin oxide powder, tantalum oxide powder, and niobium oxide powder satisfy the following condition in atomic ratio: Ta / (Sn+Ta) = 0.75~7.0%; Nb / (Ta+Nb) = 3.5–26.7%; Step S2: After adding the polyvinyl carboxylic acid dispersant to the slurry, stir for 25-35 minutes, then sand mill, then add the polyvinyl alcohol binder, disperse for 25-35 minutes, and then spray granulate to make powder. The mass ratio of the polyvinyl carboxylic acid dispersant, polyvinyl alcohol binder, and slurry is 0.05–2:0.5–4:100; The grinding speed in the aforementioned grinding process is 1000–2000 rpm, and the grinding time is 0.5–2 hours. The drying speed of the spray granulation is 10,000 to 30,000 rpm, and the drying temperature is 80 to 120°C. Step S3: The powder obtained in step S2 is cold-pressed under a pressure of 100-200 MPa to obtain a cold-pressed blank. Step S4: The cold-pressed preform is cold isostatically pressed under a pressure of 200-350 MPa to obtain a cold isostatically pressed preform. Step S5: The cold isostatic pressed blank is subjected to degreasing sintering and surface processing treatment in sequence to obtain tantalum tin oxide target material; In step S5, the degreasing and sintering process is as follows: heating at a rate of 0.2~0.7℃ / min to 520~690℃, holding for 12~38h and then degreasing; then heating at a rate of 1~5℃ / min to 1420~1580℃, holding for 6~18h and then sintering.
2. The method for preparing tantalum-containing tin oxide target material according to claim 1, characterized in that, In step S1, the purity of the tin oxide powder is not less than 99.99%, and the particle size is 0.1-10 μm. The purity of the tantalum oxide powder is not less than 99.99%, and the particle size is 0.1-30 μm; The purity of the niobium oxide powder is not less than 99.99%, and the particle size is 0.1-5 μm.
3. The method for preparing tantalum-containing tin oxide target material according to claim 2, characterized in that, In step S1, the solid content of the slurry is 50-70%.
4. The method for preparing tantalum-containing tin oxide target material according to claim 3, characterized in that, In step S2, the mass ratio of the polyvinyl carboxylic acid dispersant, polyvinyl alcohol binder, and slurry is 0.5–1:1–3:
100. The grinding speed in the aforementioned grinding process is 1200–1700 rpm, and the grinding time is 1–1.5 h. The drying speed of the spray granulation is 17,000 to 23,000 rpm, and the drying temperature is 90 to 100°C.
5. The method for preparing tantalum-containing tin oxide target material according to claim 4, characterized in that, In step S3, the pressure of the cold pressing is 130-170 MPa.
6. The method for preparing tantalum-containing tin oxide target material according to claim 5, characterized in that, In step S4, the pressure of the cold isostatic pressing is 240-330 MPa.
7. A tantalum-containing tin oxide target doped with Nb, characterized in that, The tantalum-containing tin oxide target is prepared using the preparation method described in any one of claims 1 to 6.
8. The tantalum-containing tin oxide target material according to claim 7, characterized in that, The tantalum-containing tin oxide target has a relative density ≥96% and a resistivity ≤5×10⁻⁶. -2 Ω·cm, bending strength ≥220Mpa.
Citation Information
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