CN116835981A

CN116835981A - Metal oxide target material and preparation method and application thereof

Info

Publication number: CN116835981A
Application number: CN202310818953.8A
Authority: CN
Inventors: 姚力军; 潘杰; 杨慧珍; 廖培君; 周友平
Original assignee: Ningbo Jiangfeng Electronic Material Co Ltd
Current assignee: Ningbo Jiangfeng Electronic Material Co Ltd
Priority date: 2023-07-05
Filing date: 2023-07-05
Publication date: 2023-10-03

Abstract

The invention provides a metal oxide target material, a preparation method and application thereof, wherein the preparation method comprises the following steps: mixing metal oxide, a solvent and a binder to obtain a mixture, and compacting the mixture to obtain a green body; heating and degreasing the green embryo to obtain a degreased blank; carrying out die filling and vacuum hot-pressing sintering on the degreased blank to obtain the metal oxide target; the vacuum hot-pressed sintering comprises vacuumizing, primary heating, secondary heating and tertiary heating which are sequentially carried out, wherein the primary heating starts to pressurize when reaching a first temperature; the preparation method prepares the high-purity oxide target material with the density of more than or equal to 97 percent by the mutual coordination of the steps, and the target material is not only microscopically uniform and compact, uniform and pore-free, but also has excellent sputtering performance.

Description

Metal oxide target material and preparation method and application thereof

Technical Field

The invention belongs to the technical field of sputtering targets, and relates to a metal oxide target, a preparation method and application thereof.

Background

The demand of the current market for special-shaped targets is greatly increased, the high-purity tungsten oxide ring targets cannot be stably produced in the prior art, the produced samples are low in density, micro-non-uniformity and low in yield, the requirement of the high-end electronic industry on the quality of the targets cannot be met, and the targets are only partially used in low-end products, so that the targets with high density, micro-uniformity, high target blank yield and low cost are required to be developed.

CN 106977202a discloses a preparation process of a high-purity low-density tungsten oxide target, which comprises the following preparation steps: 1) And (3) briquetting: pressing the tungsten oxide raw material powder into a platy block body by a molding press or a cold isostatic press; 2) Calcining: placing the block prepared in the step 1) in an oxygen atmosphere furnace for calcining treatment; 3) Crushing: crushing the block body calcined in the step 2), and sieving the crushed powder material with a 50-200 mesh sieve; 4) Granulating and compacting: adding a forming agent into the powder after the crushing treatment in the step 3), uniformly mixing, and then placing into a die to press by a die press to obtain a biscuit; 5) Sintering: placing the biscuit obtained in the step 4) into an oxygen atmosphere sintering furnace for sintering treatment to obtain the tungsten oxide target; however, the relative density of the tungsten oxide target material prepared by the method is low and is only in the range of 50% -80%, and the tungsten oxide target material is not prepared in a ring shape.

CN 110642526a discloses a method for preparing a tungsten oxide electrochromic film, wherein the preparation of the tungsten oxide target blank comprises the following steps: 1) Pouring tungsten oxide nano powder with the D50 particle size of 100-500 nm into deionized water containing 0.1-3 wt% of dispersing agent, and performing ball milling for 8-24 hours to form slurry; 2) The molding of the tungsten oxide target blank is realized by adopting a slip casting mode, the molded blank is dried and then is placed in cold isostatic pressing equipment, and the tungsten oxide ceramic blank with the relative density of 60-75% is formed after the cold isostatic pressing of 120-300 MPa and the pressure maintaining time of 60-600 s, so that the relative density of the prepared oxide target is lower.

Based on the above research, it is necessary to provide a preparation method of a metal oxide target material, which can obtain a target material with high purity, high density, first-order and high yield, and meet the requirements of magnetron sputtering on the purity and density of the target material.

Disclosure of Invention

The invention aims to provide a metal oxide target and a preparation method and application thereof, in particular to a tungsten oxide ring target and a preparation method and application thereof, wherein the preparation method prepares a high-purity oxide target with the density of more than or equal to 97 percent through the mutual matching of steps, and the target is uniform and compact in microcosmic, uniform and free of pores and excellent in sputtering performance.

In order to achieve the aim of the invention, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a method for preparing a metal oxide target, the method comprising the steps of:

(1) Mixing metal oxide, a solvent and a binder to obtain a mixture, and compacting the mixture to obtain a green body;

(2) Heating and degreasing the green embryo in the step (1) to obtain a degreased green embryo;

(3) Carrying out die filling and vacuum hot-pressing sintering on the degreased blank in the step (2) to obtain the metal oxide target;

the vacuum hot-pressed sintering in the step (3) comprises vacuumizing, primary heating, secondary heating and tertiary heating which are sequentially carried out, and pressurization is started when the primary heating is carried out to a first temperature.

According to the target material, firstly, metal oxide, a solvent and a binder are granulated, so that the metal oxide can be pressed into a green body, the forming degree of the metal oxide is improved, degreasing is carried out, the binder is removed, the purity of the target material is ensured, and finally, vacuum hot-pressing sintering is carried out, so that the compactness of the target material is improved; the vacuum hot-pressed sintering is performed through multi-step heating, and is vacuumized firstly, and is pressurized when the temperature is raised to the first temperature for the first time, so that the target material with high density can be obtained, if the time for starting the pressurization is changed, if the pressurization is performed again when the temperature is raised for the second time, the uniformity of the microstructure in the target blank is poor, or the pressurization is performed again when the temperature is raised for the third time, the density is likely to not reach the requirement, or after the temperature is raised for the third time, the pressurization is performed finally, the target material is likely to crack and the density is reduced.

The invention starts to pressurize when the temperature rises to the first temperature once, so that the pressurizing process, the pressure maintaining process, the subsequent heating and heat preserving processes and the like are simultaneously carried out.

Preferably, the pressurizing rate is 0.1-0.25MPa/min, for example, 0.1MPa/min, 0.15MPa/min, 0.2MPa/min or 0.25MPa/min, but the pressurizing rate is not limited to the recited values, and other non-recited values in the numerical range are equally applicable.

The pressurizing rate of the invention is matched with the heating rate and the heat preservation time of the vacuum hot-pressing sintering, if the pressurizing rate is too low, the sintering time is increased, the cost is increased, and if the pressurizing rate is too high, the target material is cracked, and the compactness is reduced.

Preferably, the pressurization is ended when the pressure is 20-30MPa, and the pressure is maintained after the pressurization is ended, for example, 20MPa, 25MPa or 30MPa, but the present invention is not limited to the recited values, and other non-recited values in the numerical range are applicable.

The end pressure of the pressurization is in a specific range, so that the density of the target can be further improved, if the end pressure of the pressurization is too low, the density requirement cannot be met, and if the end pressure of the pressurization is too high, the target is at risk of cracking.

Preferably, the rate of rise of the primary temperature rise is greater than the rate of rise of the secondary temperature rise, and the rate of rise of the secondary temperature rise is greater than the rate of rise of the tertiary temperature rise.

The temperature rising rate in different stages of the invention gradually decreases along with the rising of the temperature, thereby avoiding the influence of uneven heating on the performances such as the density, the stability and the like of the target material.

Preferably, the vacuum is applied to a degree of vacuum of 50Pa or less, for example, 50Pa, 40Pa, 30Pa, 20Pa or 10Pa, but not limited to the values listed, and other values not listed in the numerical range are equally applicable.

Preferably, the temperature rising rate of the primary temperature rising is 3-7 ℃ per minute, for example, 3 ℃ per minute, 5 ℃ per minute or 7 ℃ per minute, but the temperature rising rate is not limited to the listed values, and other values not listed in the numerical range are applicable.

Preferably, the first temperature is 600-800 ℃, for example 600 ℃, 700 ℃ or 800 ℃, and the first temperature is maintained for 1-3 hours, for example 1 hour, 2 hours or 3 hours, but not limited to the recited values, and other non-recited values in the range of values are equally applicable.

Preferably, the temperature rising rate of the secondary temperature rising is 2-5 ℃ per minute, for example, 2 ℃/min, 3 ℃/min, 4 ℃/min or 5 ℃/min, but the temperature rising rate is not limited to the recited value, and other non-recited values in the numerical range are equally applicable.

Preferably, the secondary temperature is raised to a second temperature, the second temperature is 900-1000 ℃, for example, 900 ℃, 950 ℃ or 1000 ℃, the second temperature is maintained for 0.5-2h, for example, 0.5h, 1h, 1.5h or 2h, but not limited to the recited values, and other non-recited values in the range of values are equally applicable.

Preferably, the temperature rising rate of the three temperature rising is 0.5-2 ℃ per minute, for example, 0.5 ℃ per minute, 1 ℃ per minute, 1.5 ℃ per minute or 2 ℃ per minute, but the temperature rising rate is not limited to the listed values, and other values not listed in the numerical range are equally applicable.

Preferably, the third temperature is raised to a third temperature, the third temperature is 1100-1200 ℃, for example, 1100 ℃, 1150 ℃ or 1200 ℃, the third temperature is maintained for 5-8 hours, for example, 5 hours, 6 hours, 7 hours or 8 hours, but the temperature is not limited to the listed values, and other non-listed values in the range of values are equally applicable.

Preferably, after the third temperature is maintained, the pressure is released, and the furnace is cooled to a temperature of < 100 ℃, for example, 90 ℃, 70 ℃, 50 ℃ or 30 ℃, but the pressure is not limited to the values listed, and other values not listed in the numerical range are equally applicable.

According to the vacuum hot-pressed sintering method, the temperature rising rate, the temperature, the heat preservation time and the pressurizing conditions of the multi-stage temperature rising of the vacuum hot-pressed sintering are matched with each other, so that the high-density target can be obtained.

Preferably, the degreasing blank is processed before the die filling in the step (3), and the processing is performed by adopting a non-oily cutting fluid.

In order to ensure the purity of the oxide target, the invention adopts the non-oily cutting fluid for processing, so that the rear blank can be loaded into a die for vacuum pressure sintering, and if the oily cutting fluid is adopted, oily impurities are doped on the target, thereby not only influencing the purity of the target, but also influencing the effect of vacuum pressure sintering.

Preferably, the non-oily cutting fluid comprises pure water and/or alcohol.

Preferably, the die-filling die in the step (3) is separated from the degreased blank by high-temperature-resistant glass wool and/or graphite paper.

Preferably, the die in the step (3) is a graphite die, and the die is placed in a vacuum sintering furnace, and the die level is ensured after the die is placed.

Preferably, the temperature of the heating degreasing in the step (2) is 200-400 ℃, for example, 200 ℃, 300 ℃ or 400 ℃, the time is 12 hours or more, for example, 12 hours, 14 hours, 16 hours or 18 hours, but the heating degreasing method is not limited to the listed values, and other non-listed values in the numerical range are equally applicable.

Preferably, the thermal degreasing of step (2) is performed under a circulating air atmosphere.

Preferably, the compacting of step (1) comprises loading the mixture of step (1) into a mould for cold isostatic pressing.

Preferably, the mould used for cold isostatic pressing is an annular mould, preferably an annular gum cover.

The preparation method is suitable for preparing the annular target material, and the obtained annular target material is high in forming degree and density.

Preferably, the pressure of the cold isostatic pressing is 150-280MPa, for example 150MPa, 200MPa, 250MPa or 280MPa, and the time is 5-15min, for example 5min, 10min or 15min, but not limited to the recited values, and other values not recited in the numerical range are equally applicable.

Preferably, the metal oxide of step (1) comprises tungsten oxide.

The preparation method is suitable for preparing tungsten oxide ring targets, and the high-density target materials can not be obtained due to the variety change of metal oxides and the shape change of molding.

The particle diameter D50 of the tungsten oxide is preferably 5 μm or less, for example, 5 μm, 4 μm, 3 μm, 2 μm or 1 μm, and the purity is 99.9% or more, for example, 99.9%, 99.92%, 99.94% or 99.96%, but not limited to the values listed, and other values not listed in the numerical range are applicable.

Preferably, the binder in step (1) is added in an amount of 0.5 to 2wt% based on the mass of the metal oxide, for example, 0.5wt%, 1wt% or 2wt%, and the solvent is added in an amount of 1 to 5wt% based on the mass of the metal oxide, for example, 1wt%, 3wt% or 5wt%, but not limited to the values recited, and other non-recited values in the numerical range are equally applicable.

Preferably, the solvent comprises high purity water, the binder comprises a water-soluble binder comprising polyvinyl alcohol and/or polyethylene glycol.

Preferably, the mixing in step (1) comprises ball milling, the ball ratio of the ball milling mixture is (2-5): 1, for example, the ball ratio can be 2:1, 3:1, 4:1 or 5:1, the time is more than 24 hours, for example, 24 hours, 28 hours, 32 hours or 36 hours, the ball milling mixture is not limited to the listed values, and other non-listed values in the range of values are equally applicable.

As a preferable technical scheme of the preparation method, the preparation method comprises the following steps:

(1) Ball milling and mixing metal oxide, solvent and binder in the ball ratio of (2-5) to 1 for over 24 hr to obtain mixed material, wherein the amount of the binder is 0.5-2wt% of the metal oxide, the amount of the solvent is 1-5wt% of the metal oxide, the metal oxide is tungsten oxide with particle size D50 below 5 microns and purity over 99.9%;

filling the mixture into an annular die, and carrying out cold isostatic pressing for 5-15min at the pressure of 150-280MPa to obtain a green body;

(2) Heating and degreasing the green embryo in the step (1) for more than 12 hours at the temperature of 200-400 ℃ in the circulating air atmosphere to obtain a degreased blank;

(3) Processing and die-filling the degreased blank in the step (2) by adopting a non-oily cutting fluid, wherein a die for die filling and the degreased blank are separated by high-temperature resistant glass wool and/or graphite paper, vacuumizing until the vacuum degree is below 50Pa, heating to 600-800 ℃ at a heating rate of 3-7 ℃/min for 1-3 hours, heating to 900-1000 ℃ at a heating rate of 2-5 ℃/min for 0.5-2 hours, heating to 1100-1200 ℃ at a heating rate of 0.5-2 ℃/min for 5-8 hours, decompressing after heat preservation, and cooling to a temperature of less than 100 ℃ along with a furnace to obtain the metal oxide target;

wherein, when the temperature is raised to 600-800 ℃, pressurizing is started at the speed of 0.1-0.25MPa/min, and when the pressure is 20-30MPa, pressurizing is ended for maintaining pressure.

In a second aspect, the invention provides a metal oxide target produced by the method of the first aspect, the metal oxide target having a density of 97% or more, for example 97%, 97.5%, 98%, 98.5%, 99%, 99.5% or 99.9%, but not limited to the values recited, and other non-recited values within the range of values are equally applicable.

In a third aspect, the present invention provides the use of a metal oxide target according to the second aspect, including in electrochromic films.

Compared with the prior art, the invention has the following beneficial effects:

according to the invention, the metal oxide, the solvent and the binder are granulated, so that the metal oxide can be pressed into a green body, the forming degree of the metal oxide is improved, degreasing is performed, the binder is removed, the purity of the target material is ensured, and finally vacuum hot-pressed sintering is performed, so that the density of the target material is improved by mutually matching the conditions of the vacuum hot-pressed sintering, and the high-purity tungsten oxide ring target with the density of more than or equal to 97% can be obtained.

Detailed Description

The technical scheme of the invention is further described by the following specific embodiments. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.

Example 1

The embodiment provides a preparation method of a metal oxide target, which comprises the following steps:

(1) Ball milling and mixing a metal oxide, a solvent and a binder for 30 hours according to a ball ratio of 3:1 to obtain a mixture, wherein the binder is polyethylene glycol, the addition amount of the binder is 1.5wt% of the mass of the metal oxide, the solvent is high-purity water, the addition amount of the solvent is 3wt% of the mass of the metal oxide, the metal oxide is tungsten oxide with a particle size D50 of 3 mu m and a purity of 99.95%;

filling the mixture into an annular rubber sleeve, and carrying out cold isostatic pressing for 10min at the pressure of 200MPa to obtain a green body;

(2) Heating and degreasing the green embryo in the step (1) for 15 hours at the temperature of 300 ℃ in the circulating air atmosphere to obtain a degreased blank;

(3) Processing and die-filling the degreased blank in the step (2) by adopting non-oily cutting fluid (pure water), wherein a graphite die for die filling is separated from the degreased blank by high-temperature-resistant glass wool, and the graphite die is placed in a vacuum sintering furnace, and the die is ensured to be horizontally sintered under vacuum pressure after being placed;

the vacuum pressure sintering comprises: then vacuumizing to the vacuum degree of 30Pa, heating to 700 ℃ at a heating rate of 5 ℃/min for 2 hours, heating to 950 ℃ at a heating rate of 3.5 ℃/min for 1.5 hours, heating to 1150 ℃ at a heating rate of 1.5 ℃/min for three times, heating to 6.5 hours, decompressing after the heat preservation is finished, and cooling to 30 ℃ along with a furnace to obtain the metal oxide target;

wherein, when the temperature is raised to 700 ℃, pressurizing is started at the speed of 0.15MPa/min, and when the pressure is 25MPa, pressurizing is ended, and pressure maintaining is carried out.

Example 2

(1) Ball milling and mixing metal oxide, a solvent and a binder for 24 hours according to a ball ratio of 2:1 to obtain a mixture, wherein the binder is polyvinyl alcohol, the addition amount of the binder is 0.5wt% of the mass of the metal oxide, the solvent is high-purity water, the addition amount of the solvent is 5wt% of the mass of the metal oxide, and the metal oxide is tungsten oxide with a particle size D50 of 5 mu m and a purity of 99.9%;

filling the mixture into an annular rubber sleeve, and carrying out cold isostatic pressing for 15min at the pressure of 150MPa to obtain a green body;

(2) Heating and degreasing the green embryo in the step (1) for 12 hours at the temperature of 400 ℃ in a circulating air atmosphere to obtain a degreased blank;

(3) Processing and die-filling the degreased blank in the step (2) by adopting non-oily cutting fluid (pure water), wherein a graphite die for die filling is separated from the degreased blank by graphite paper, and the graphite die is placed in a vacuum sintering furnace, and the die is ensured to be horizontally sintered under vacuum pressure after being placed;

the vacuum pressure sintering comprises: then vacuumizing to the vacuum degree of 50Pa, heating to 600 ℃ at a heating rate of 3 ℃/min for 3 hours, heating to 900 ℃ at a heating rate of 2 ℃/min for 2 hours, heating to 1100 ℃ at a heating rate of 0.5 ℃/min for three times, heating to 8 hours, decompressing after the heat preservation is finished, and cooling to 50 ℃ along with a furnace to obtain the metal oxide target;

wherein, when the temperature is raised to 600 ℃ at one time, pressurizing is started at the speed of 0.1MPa/min, and when the pressure is 20MPa, pressurizing is ended, and pressure maintaining is carried out.

Example 3

(1) Ball milling and mixing a metal oxide, a solvent and a binder for 30 hours according to a ball ratio of 5:1 to obtain a mixture, wherein the binder is polyethylene glycol, the addition amount of the binder is 2wt% of the mass of the metal oxide, the solvent is high-purity water, the addition amount of the solvent is 1wt% of the mass of the metal oxide, and the metal oxide is tungsten oxide with a particle size D50 of 1 mu m and a purity of 99.92%;

filling the mixture into an annular rubber sleeve, and carrying out cold isostatic pressing for 5min at the pressure of 280MPa to obtain a green body;

(2) Heating and degreasing the green embryo in the step (1) for 14h at the temperature of 200 ℃ in the circulating air atmosphere to obtain a degreased blank;

(3) Processing and die-filling the degreased blank in the step (2) by adopting non-oily cutting fluid (alcohol), wherein a graphite die for die filling is separated from the degreased blank by graphite paper, and the graphite die is placed in a vacuum sintering furnace, and the die is ensured to be horizontally sintered under vacuum pressure after being placed;

the vacuum pressure sintering comprises: vacuumizing until the vacuum degree is 50Pa, heating to 800 ℃ at a heating rate of 7 ℃/min for 1h, heating to 1000 ℃ at a heating rate of 5 ℃/min for 0.5h, heating to 1200 ℃ at a heating rate of 2 ℃/min for 5h, decompressing after the heat preservation is finished, and cooling to 80 ℃ along with a furnace to obtain the metal oxide target;

wherein, when the temperature is raised to 800 ℃ at one time, pressurizing is started at a rate of 0.25MPa/min, and when the pressure is 30MPa, pressurizing is ended, and pressure maintaining is performed.

Example 4

This example provides a method of preparing a metal oxide target, which is the same as example 1, except that the pressurizing rate in step (3) is 0.03 MPa/min.

Example 5

This example provides a method of preparing a metal oxide target, which is the same as example 1, except that the pressurizing rate in step (3) is 0.4 MPa/min.

Example 6

This example provides a method of producing a metal oxide target, which is the same as example 1, except that the pressurizing to a pressure of 45MPa is performed in step (3).

Example 7

This example provides a method of producing a metal oxide target, which is the same as example 1, except that the pressurizing to a pressure of 5MPa is performed in step (3).

Example 8

This example provides a method for producing a metal oxide target, which is the same as example 1 except that the temperature rise rate of the secondary temperature rise in step (3) is 1 ℃/min.

Example 9

This example provides a method for producing a metal oxide target, which is the same as example 1 except that the temperature rise rate of the secondary temperature rise in step (3) is 6.5 ℃/min.

Example 10

This example provides a method for producing a metal oxide target, which is the same as example 1 except that the one-time temperature increase rate of step (3) is 1 ℃/min.

Example 11

This example provides a method for producing a metal oxide target, which is the same as example 1 except that the temperature rise rate of the tertiary temperature rise in step (3) is 5 ℃/min.

Example 12

This example provides a method of preparing a metal oxide target, which is the same as example 1 except that the temperature is raised to 500 ℃ at one time in step (3).

Example 13

This example provides a method of preparing a metal oxide target, which is the same as example 1 except that the temperature is raised to 900 ℃ at one time in step (3).

Example 14

This example provides a method of preparing a metal oxide target, which is the same as example 1 except that the secondary temperature is raised to 800 ℃ in step (3).

Example 15

This example provides a method of preparing a metal oxide target, which is the same as example 1 except that the secondary temperature is raised to 1100 ℃ in step (3).

Example 16

This example provides a method for preparing a metal oxide target, which is the same as example 1 except that the metal oxide in step (1) is silicon oxide having a particle diameter D50 of 3 μm and a purity of 99.95%.

Example 17

The present embodiment provides a method for producing a metal oxide target, which is the same as that of embodiment 1 except that the mold in step (1) is a cylindrical mold.

Comparative example 1

This comparative example provides a method for preparing a metal oxide target, which is the same as example 1, except that pressurization is started after the secondary temperature is raised to 950 ℃ in step (3).

Comparative example 2

This comparative example provides a method for producing a metal oxide target, which is the same as example 1 except that pressurization is started after the temperature is raised to 1150 ℃ three times in step (3).

Comparative example 3

This comparative example provides a method for producing a metal oxide target, which is the same as example 1 except that the three times of heating to 1150 ℃ in step (3) and maintaining the temperature for 6.5 hours, then starting pressurizing at a rate of 0.15MPa/min until the pressure is 25MPa, and then maintaining the pressure for 6.5 hours.

The metal oxide targets obtained in the above examples and comparative examples were subjected to a density test by the following method: the drainage method and the test results are shown in Table 1.

TABLE 1

From the above table it can be seen that:

the target material obtained by the invention has high density, and can obtain a special-shaped target material with high density; specifically, as can be seen from examples 1 and comparative examples 1 to 3, the timing of pressurization of the present invention greatly affects the density of the target; as can be seen from examples 1 and 4-7, the pressurizing rate and the pressurizing end point pressure of the present invention affect the vacuum pressurizing sintering effect, thereby affecting the compactness of the target; as is clear from examples 1 and 8 to 15, the trend of the temperature rising rate of the primary temperature rising, the secondary temperature rising and the tertiary temperature rising and the end temperature of the temperature rising also affect the effect of the vacuum pressure sintering; as can be seen from examples 1 and examples 16-17, the preparation method of the present invention is more preferably applied to tungsten oxide ring targets.

In summary, the invention provides a metal oxide target, and a preparation method and application thereof, wherein the preparation method prepares the high-purity oxide target with the density of more than or equal to 97% through the mutual coordination of the steps, and the target is uniform and compact in microcosmic, uniform and free of pores, and excellent in sputtering performance.

The foregoing is merely illustrative of the present invention, and the present invention is not limited thereto, and it should be apparent to those skilled in the art that any changes or substitutions that fall within the technical scope of the present invention disclosed herein are within the scope of the present invention.

Claims

1. The preparation method of the metal oxide target material is characterized by comprising the following steps of:

2. The method of claim 1, wherein the rate of pressurization is 0.1-0.25MPa/min;

preferably, the pressurizing is finished when the pressure is 20-30MPa, and the pressure maintaining is performed after the pressurizing is finished.

3. The production method according to claim 1 or 2, wherein a temperature rise rate of the primary temperature rise is greater than a temperature rise rate of the secondary temperature rise, and the temperature rise rate of the secondary temperature rise is greater than a temperature rise rate of the tertiary temperature rise;

preferably, the vacuum is pumped to a vacuum degree of below 50 Pa;

preferably, the temperature rising rate of the primary temperature rising is 3-7 ℃/min;

preferably, the first temperature is 600-800 ℃, and the first temperature is maintained for 1-3 hours.

4. A method of preparation according to any one of claims 1 to 3 wherein the rate of rise of the secondary temperature is 2 to 5 ℃/min;

preferably, the secondary temperature is raised to a second temperature, the second temperature is 900-1000 ℃, and the time for maintaining the second temperature is 0.5-2h;

preferably, the temperature rising rate of the three temperature rising is 0.5-2 ℃/min;

preferably, the temperature is raised to a third temperature for three times, the third temperature is 1100-1200 ℃, and the time for maintaining the third temperature is 5-8h;

preferably, after the third temperature is kept, the pressure is relieved, and the temperature is cooled to be less than 100 ℃ along with the furnace.

5. The method according to any one of claims 1 to 4, wherein the degreasing and blank processing is performed before the die filling in step (3), and the processing is performed by using a non-oily cutting fluid;

6. The method according to any one of claims 1 to 5, wherein the temperature of the degreasing by heating in step (2) is 200 to 400 ℃ for 12 hours or longer;

preferably, the heating degreasing of step (2) is performed under a circulating air atmosphere;

preferably, the compacting of step (1) comprises loading the mixture of step (1) into a mould for cold isostatic pressing;

preferably, the mould used for cold isostatic pressing is an annular mould;

preferably, the pressure of the cold isostatic pressing is 150-280MPa and the time is 5-15min.

7. The method of any one of claims 1-6, wherein the metal oxide of step (1) comprises tungsten oxide;

preferably, the tungsten oxide has a particle diameter D50 of 5 μm or less and a purity of 99.9% or more;

preferably, the addition amount of the binder in the step (1) is 0.5-2wt% of the mass of the metal oxide, and the addition amount of the solvent is 1-5wt% of the mass of the metal oxide;

preferably, the solvent comprises high purity water and the binder comprises a water-soluble binder;

preferably, the mixing in the step (1) comprises ball milling mixing, wherein the ball ratio of the ball milling mixing is (2-5): 1, and the time is more than 24 hours.

8. The preparation method according to any one of claims 1 to 7, characterized in that the preparation method comprises the steps of:

(1) Ball milling and mixing metal oxide, solvent and adhesive in the ball ratio of (2-5) to 1 for over 24 hr to obtain mixed material, wherein the adhesive accounts for 0.5-2wt% of the metal oxide, the solvent accounts for 1-5wt% of the metal oxide, and the metal oxide is tungsten oxide with particle size D50 below 5 microns and purity over 99.9%;

9. A metal oxide target produced by the production method according to any one of claims 1 to 8, wherein the metal oxide target has a density of 97% or more.

10. Use of a metal oxide target according to claim 9, wherein the use comprises use in electrochromic films.