CN113880578B

CN113880578B - Preparation method of Ho2Zr2O7 magneto-optical ceramic with high optical quality

Info

Publication number: CN113880578B
Application number: CN202111365742.0A
Authority: CN
Inventors: 吕滨; 胡良斌
Original assignee: Ningbo University
Current assignee: Ningbo University
Priority date: 2021-11-05
Filing date: 2021-11-05
Publication date: 2022-11-01
Anticipated expiration: 2041-11-05
Also published as: CN113880578A

Abstract

The invention relates to a Ho with high optical quality₂Zr₂O₇A method for preparing magneto-optical ceramics. Holmium nitrate pentahydrate and zirconium nitrate pentahydrate are dissolved in deionized water and fully mixed to prepare a mother salt solution, the mother salt solution is added into an atomizer for atomization, atomized liquid drops are introduced into a vertical tubular furnace, and a cesium chloride solution is introduced into the vertical tubular furnace by a metering pump to serve as a dispersing agent; roasting at low temperature in a vertical tubular furnace to obtain an intermediate product, and then roasting at high temperature to obtain Ho₂Zr₂O₇Ceramic powder; then pre-pressing, cold isostatic pressing, vacuum sintering, annealing, grinding and polishing to obtain Ho₂Zr₂O₇Magneto-optical ceramics. The advantages are that: the obtained ceramic powder has good dispersibility and uniform particle size; ho with excellent optical quality and high Verdet constant can be prepared by using the powder₂Zr₂O₇The magneto-optical ceramic has higher application potential in a high average power laser system.

Description

Ho with high optical quality2Zr2O7Preparation method of magneto-optical ceramic

Technical Field

The invention relates to a Ho with high optical quality₂Zr₂O₇A method for preparing magneto-optical ceramics.

Background

Magneto-optical materials are indispensable in the manufacture of critical magneto-optical components such as faraday rotators and isolators of high average power laser systems. The magneto-optical material mainly comprises glass, crystal and ceramic, wherein the magneto-optical ceramic has the advantages of high thermal stability, high thermal shock resistance, near-net shape, large-size preparation and the like, and gradually becomes a research hotspot in the field of magneto-optical materials. With the continuous development of magneto-optical devices towards high power, miniaturization, low cost, and the like, the requirements on the performance of magneto-optical materials are higher and higher, mainly including high verdet constant, large size, high optical quality, and the like. The basic physical properties of TGG (terbium gallium garnet) ceramics have been demonstrated to be comparable to the corresponding single crystals and are therefore considered single crystal alternatives for use in high average power faraday isolators.

A₂B₂O₇The compound has the advantages of high density, excellent mechanical property, high melting point and the like. Therefore, they are widely used in the fields of thermal barrier coatings, solid oxide fuel cells, catalysts, scintillator matrix materials, solidification of actinide nuclear waste, solid state laser materials, and the like. Ho₂Zr₂O₇The ceramic is A₂B₂O₇One of the type compounds has a crystal structure of cubic system and a defective fluorite structure, and has good properties in both visible light region and near infrared regionTransmittance, and expected high verdet constant, is a typical magneto-optical transparent ceramic material and has potential practical applications.

Ho due to the high melting point of the raw material₂Zr₂O₇The crystals have few growth conditions and thus the preparation of ceramics is a feasible method.

The invention aims to provide the Ho with good optical quality and excellent magneto-optical performance₂Zr₂O₇A method for preparing ceramics. Nitrate of holmium and zirconium is used as mother salt, cesium chloride is used as dispersant, an intermediate product with good dispersity and uniform granularity is prepared by adopting a spray roasting method, the intermediate product is roasted in an oxygen atmosphere to generate solid phase reaction and remove impurities, and high-density Ho is obtained by vacuum sintering₂Zr₂O₇Magneto-optical transparent ceramics.

The technical scheme of the invention is as follows:

ho with high optical quality₂Zr₂O₇The preparation method of the magneto-optical ceramic comprises the following specific steps:

(1) Mixing holmium nitrate pentahydrate and zirconium nitrate pentahydrate according to the cation molar ratio of 1: 1, adding deionized water, dissolving the holmium nitrate pentahydrate and the zirconium nitrate pentahydrate to prepare a mother salt solution, and fully stirring.

(2) Adding the mother salt solution obtained in the step (1) into an atomizer to obtain mist-shaped liquid drops, introducing the mist-shaped liquid drops into a vertical tubular furnace, and simultaneously introducing a cesium chloride solution; collecting an intermediate product obtained by low-temperature roasting in a vertical tubular furnace through a bag filter; in order to collect the intermediate product obtained by low-temperature roasting, the bag filter is subjected to air suction during the low-temperature roasting process, so that a downward air flow is generated.

(3) Calcining the intermediate product prepared in the step (2) at high temperature in an oxygen atmosphere to obtain Ho₂Zr₂O₇And (3) powder.

(4)Ho₂Zr₂O₇The powder is sequentially subjected to prepressing and cold isostatic pressing forming, and then is subjected to densification sintering in vacuum to obtain Ho₂Zr₂O₇A ceramic; then annealing in a tube furnace under oxygen atmosphere, and finally feeding the sampleAnd (5) line sanding and polishing.

Further, in the step (1), the mother salt solution is prepared by fully dissolving holmium nitrate pentahydrate and analytically pure zirconium nitrate pentahydrate with the purity of more than 99.99% in deionized water, and the concentration of cations in the mother salt solution is 0.24-0.48 mol/L.

Further, in the step (2), the atomization spraying speed of the solution is 0.5 mL/min-3 mL/min.

Further, in the step (2), the concentration of the cesium chloride solution is 0.01 mol/L-0.05 mol/L.

Further, in the step (2), the doping amount of the cesium chloride solution is controlled by a metering pump, and the doping amount is controlled to be 0.1-0.5% of the total amount of the cationic substances.

Further, in the step (2), the low-temperature roasting temperature is 400-900 ℃.

Further, in the step (3), the intermediate product is calcined at high temperature under the atmosphere of oxygen concentration of 99.99% and flow rate of 100mL/min, the calcining temperature is 1000-1400 ℃, and the calcining time is 1-6 h.

Further, in the step (4), the pressure intensity is 100 MPa-400 MPa during cold isostatic pressing.

Further, in the step (4), the sintering temperature is 1600-2000 ℃, the sintering time is 2-6 h, and the vacuum degree is 10^-4Pa～10^-5Pa。

Further, in the step (4), annealing is carried out under the atmosphere with the oxygen concentration of 99.99% and the flow rate of 100mL/min, the annealing temperature is 1100-1700 ℃, and the annealing time is 2-6 h.

Compared with the prior art, the invention has the advantages that:

according to the invention, cesium chloride is used as a dispersing agent, so that the ZETA potential among atomized particles is further improved, an intermediate product with small particle size and good dispersibility is obtained, and the phenomena of agglomeration and uneven texture possibly caused by other preparation methods are avoided. The intermediate product with better dispersibility can be used for obtaining Ho with high compactness and good optical property₂Zr₂O₇A ceramic material. In addition, the valence of cesium ion is in combination with holmium,The difference of zirconium ions can create crystal defects in the ceramic sintering process, so that the addition of cesium chloride also plays a role of a sintering aid. The Ho prepared by the method is verified by the invention₂Zr₂O₇The ceramic has a transmittance of about 76% at a light wavelength of 700 nm. The Faraday magneto-optical effect test shows that Ho₂Zr₂O₇The verdet constant of the ceramic at 635nm of the polarized light wavelength is about-150 rad.T^-1m^-1About 1.1 times of that of a commercial terbium gallium garnet crystal. The invention prepares Ho with high optical quality₂Zr₂O₇The magneto-optical ceramic has higher practical application value in the field of magneto-optical materials.

Drawings

FIG. 1 is a scanning electron microscope morphology of a ceramic powder obtained by the preparation method of the present invention (corresponding to example 1);

FIG. 2 is an X-ray diffraction chart of a ceramic powder obtained by the production process of the present invention (corresponding to example 1);

FIG. 3 shows Ho obtained by the preparation process of the present invention (corresponding to example 1)₂Zr₂O₇A ceramic;

FIG. 4 shows Ho obtained by the preparation method of the present invention (corresponding to example 2)₂Zr₂O₇A ceramic;

FIG. 5 shows Ho obtained by the preparation process of the present invention (corresponding to example 3)₂Zr₂O₇A ceramic;

FIG. 6 shows Ho obtained by the preparation process of the present invention (corresponding to example 4)₂Zr₂O₇A ceramic;

FIG. 7 shows Ho obtained by the preparation process of the present invention (corresponding to example 5)₂Zr₂O₇A ceramic;

FIG. 8 shows Ho obtained by the preparation process of the present invention (corresponding to example 1)₂Zr₂O₇The transmittance curve of the ceramic in the ultraviolet-visible band.

Detailed Description

The invention is described in further detail below with reference to the following examples of the drawings.

Example 1

The method comprises the following steps: mixing holmium nitrate pentahydrate and zirconium nitrate pentahydrate according to the cation molar ratio of 1: 1, adding deionized water, dissolving the two to prepare a mother salt solution of 0.24mol/L, and fully stirring.

Step two: adding the mother salt solution obtained in the step one into an atomizer to obtain mist-shaped liquid drops, introducing the mist-shaped liquid drops into a vertical tubular furnace at the speed of 0.5mL/min, and simultaneously introducing a 0.1% cesium chloride solution with the concentration of 0.01mol/L by using a metering pump; roasting in air at low temperature of 400 ℃ by a vertical tubular furnace.

Step three: collecting an intermediate product obtained by low-temperature roasting through a bag filter; in order to collect the intermediate product obtained by low-temperature roasting, the bag filter is subjected to air suction during the roasting process so as to generate downward airflow.

Step four: calcining the intermediate product obtained in the third step at 1000 ℃ for 6 hours under the oxygen atmosphere condition to obtain Ho₂Zr₂O₇And (3) powder.

Step five: for Ho₂Zr₂O₇Sequentially pre-pressing and cold isostatic pressing the powder under the pressure of 300MPa, sintering the formed product at 2000 deg.C under vacuum condition for 2h and vacuum degree of 10^-4Pa; annealing in an oxygen atmosphere after sintering is finished, wherein the annealing temperature is controlled at 1700 ℃, and the annealing time is 2h; finally, grinding and polishing the sample to obtain Ho₂Zr₂O₇And (3) ceramic.

Example 2

The method comprises the following steps: mixing holmium nitrate pentahydrate and zirconium nitrate pentahydrate according to the cation molar ratio of 1: 1, adding deionized water, dissolving the holmium nitrate pentahydrate and the zirconium nitrate pentahydrate to prepare a 0.36mol/L mother salt solution, and fully stirring.

Step two: adding the mother salt solution obtained in the step one into an atomizer to obtain mist-shaped liquid drops, introducing the mist-shaped liquid drops into a tubular furnace at the speed of 2mL/min, and simultaneously introducing a 0.3% cesium chloride solution with the concentration of 0.03mol/L by using a metering pump; roasting the mixture in air at low temperature of 600 ℃ by a vertical tubular furnace.

Step three: collecting an intermediate product obtained by low-temperature roasting through a bag filter; in order to collect the intermediate product obtained by low-temperature roasting, the bag filter is subjected to air suction during roasting so as to generate downward air flow.

Step four: calcining the intermediate product obtained in the third step at 1200 ℃ for 4 hours in an oxygen atmosphere to obtain Ho₂Zr₂O₇Powder;

step five: to Ho₂Zr₂O₇Sequentially pre-pressing and cold isostatic pressing the powder under the pressure of 400MPa, and sintering the formed product at 1850 ℃ for 4h under the vacuum condition with the vacuum degree of 10^-5Pa; annealing in an oxygen atmosphere after sintering is finished, wherein the annealing temperature is controlled at 1500 ℃, and the annealing time is 3h; finally, grinding and polishing the sample to obtain Ho₂Zr₂O₇A ceramic.

Example 3

The method comprises the following steps: mixing holmium nitrate pentahydrate and zirconium nitrate pentahydrate according to the cation molar ratio of 1: 1, adding deionized water, dissolving the two to prepare a mother salt solution of 0.48mol/L, and fully stirring.

Step two: adding the mother salt solution obtained in the first step into an atomizer to obtain mist liquid drops, introducing the mist liquid drops into a vertical tubular furnace at the speed of 3mL/min, and simultaneously introducing a 0.5% cesium chloride solution with the concentration of 0.05mol/L by using a metering pump; roasting the mixture in air at low temperature of 900 ℃ by a vertical tubular furnace.

Step four: calcining the intermediate product obtained in the third step for 1h at 1400 ℃ under the oxygen atmosphere condition to obtain Ho₂Zr₂O₇And (3) powder.

Step five: to Ho₂Zr₂O₇Sequentially pre-pressing and cold isostatic pressing the powder under the pressure of 100MPa, and sintering the formed product for 6h under the vacuum condition of 1600 ℃ and the vacuum degree of 10^-5Pa; after sintering, in the presence of oxygenAnnealing in the atmosphere, wherein the annealing temperature is controlled at 1100 ℃, and the annealing time is 6h; finally, grinding and polishing the sample to obtain Ho₂Zr₂O₇A ceramic.

Example 4

The method comprises the following steps: mixing holmium nitrate pentahydrate and zirconium nitrate pentahydrate according to the cation molar ratio of 1: 1, adding deionized water, dissolving the holmium nitrate pentahydrate and the zirconium nitrate pentahydrate to prepare a 0.24mol/L mother salt solution, and fully stirring.

Step two: adding the mother salt solution obtained in the step one into an atomizer to obtain mist liquid drops, introducing the mist liquid drops into a vertical tubular furnace at the speed of 0.5L/min, and simultaneously introducing a 0.1% cesium chloride solution with the concentration of 0.01mol/L by using a metering pump; roasting the mixture in air at a low temperature of 400 ℃ by a vertical tubular furnace.

Step four: calcining the intermediate product obtained in the third step at 1000 ℃ for 6 hours in an oxygen atmosphere to obtain Ho₂Zr₂O₇Powder;

step five: for Ho₂Zr₂O₇Sequentially pre-pressing and cold isostatic pressing the powder under the pressure of 100MPa, and sintering the formed product for 6h under the vacuum condition of 1600 ℃ and the vacuum degree of 10^-4Pa; finally, grinding and polishing the sample to obtain Ho₂Zr₂O₇And (3) ceramic.

Example 5

The method comprises the following steps: mixing holmium nitrate pentahydrate and zirconium nitrate pentahydrate according to the cation molar ratio of 1: 1, adding deionized water, dissolving the two to prepare a mother salt solution of 0.36mol/L, and fully stirring.

Step two: adding the mother salt solution obtained in the step one into an atomizer to obtain mist-shaped liquid drops, introducing the mist-shaped liquid drops into a vertical tubular furnace at the speed of 2mL/min, and simultaneously introducing a 0.3% cesium chloride solution with the concentration of 0.03mol/L by using a metering pump; roasting in air at low temperature of 600 ℃ by a vertical tubular furnace.

Step four: calcining the intermediate product obtained in the third step at 1200 ℃ for 4 hours in an oxygen atmosphere to obtain Ho₂Zr₂O₇And (3) powder.

Step five: for Ho₂Zr₂O₇Sequentially pre-pressing and cold isostatic pressing the powder under the pressure of 250MPa, and sintering the formed product at 1850 ℃ under the vacuum condition for 4h with the vacuum degree of 10^-5Pa; finally, grinding and polishing the sample to obtain Ho₂Zr₂O₇A ceramic.

FIG. 1 shows a Scanning Electron Microscope (SEM) photograph of the ceramic powder prepared in example 1, and it can be seen that Ho₂Zr₂O₇The ceramic powder is in a sphere-like shape, and has the advantages of good dispersibility, fine particle size, uniform particle size distribution and no hard aggregates.

Fig. 2 shows an X-ray diffraction (XRD) pattern of the intermediate product prepared by the preparation method of example 1 after calcination in an oxygen atmosphere. In fig. 2, the abscissa degree represents the scan angle, and the ordinate Intensity represents the Intensity. As can be seen from FIG. 2, the powder exhibits a pure phase Ho₂Zr₂O₇The structure of (2) has sharp diffraction peak and good crystallinity.

Ho prepared by the preparation methods of example 1, example 2, example 3, example 4 and example 5 are correspondingly given in FIG. 3, FIG. 4, FIG. 5, FIG. 6 and FIG. 7 respectively₂Zr₂O₇And (3) a photo of a polished sample obtained after the ceramic is ground and polished. As can be seen from fig. 3 and 4, when the polished sample is placed on the paper with letters, the letters can be read through the polished sample, and the optical quality is high; however, as can be seen from fig. 5, the ceramic transmittance is not high, and only the characters can be read through the polished sample; as can be seen in FIGS. 6 and 7, the ceramic samples were completely opaque and black, with the main effect being thatIs caused by high-temperature annealing in the absence of oxygen atmosphere; analysis of FIGS. 3, 4, 5, 6, and 7 corresponds to Ho prepared by the processes of example 1, 2, 3, 4, and 5₂Zr₂O₇The optical quality of the ceramics is different, which reflects Ho₂Zr₂O₇The optical quality of ceramics varies largely in relation to the annealing procedure; in addition, the quality of the prepared intermediate product, the calcination temperature of the powder, the addition amount of cesium chloride, the ceramic molding pressure and the sintering process can influence the transmittance of the sample to different degrees.

FIG. 8 shows Ho prepared by the preparation method of example 1₂Zr₂O₇Transmittance curve of ceramic. In fig. 8, the abscissa Wavelength represents the Wavelength, and the ordinate transmittince represents the Transmittance. Tested, ho prepared by spray roasting method₂Zr₂O₇The ceramic has a transmittance of about 76% at a wavelength of 700 nm.

For Ho shown in FIG. 3 and FIG. 4₂Zr₂O₇The Faraday magneto-optical effect test of the ceramics shows that Ho₂Zr₂O₇The verdet constant of the ceramic at 635nm of the polarized light wavelength is about-150 rad.T^-1m^-1Slightly higher than commercial terbium gallium garnet crystals. Thus, ho₂Zr₂O₇Ceramics have a high potential for use in high average power laser systems.

The above description is only exemplary of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. Ho with high optical quality₂Zr₂O₇The preparation method of the magneto-optical ceramic comprises the following specific steps:

(1) Mixing holmium nitrate pentahydrate and zirconium nitrate pentahydrate according to the cation molar ratio of 1: 1, adding deionized water and dissolving the two to prepare a mother salt solution, and fully stirring;

(2) Adding the prepared mother salt solution into an atomizer to obtain mist-shaped liquid drops, introducing the mist-shaped liquid drops into a vertical tubular furnace, and simultaneously introducing a cesium chloride solution; collecting an intermediate product obtained by low-temperature roasting in a vertical tubular furnace through a bag filter; in order to collect the intermediate product obtained by low-temperature roasting, the bag filter is pumped in the roasting process to generate downward airflow;

(3) Calcining the intermediate product prepared in the step (2) in an oxygen atmosphere to obtain Ho₂Zr₂O₇Powder;

(4)Ho₂Zr₂O₇the powder is sequentially subjected to prepressing and cold isostatic pressing forming, and then is subjected to densification sintering in vacuum to obtain Ho₂Zr₂O₇A ceramic; then annealing in a tube furnace under an oxygen atmosphere, and finally grinding and polishing the sample.

2. A high optical quality Ho according to claim 1₂Zr₂O₇The preparation method of the magneto-optical ceramic is characterized by comprising the following steps: in the step (1), the mother salt solution is prepared by fully dissolving holmium nitrate pentahydrate and analytically pure zirconium nitrate pentahydrate with the purity of more than or equal to 99.99 percent in deionized water; the concentration of the cation in the mother salt solution is 0.24 mol/L-0.48 mol/L.

3. A high optical quality Ho according to claim 1₂Zr₂O₇The preparation method of the magneto-optical ceramic is characterized by comprising the following steps: in the step (2), the atomization spraying speed of the solution is 0.5 mL/min-3 mL/min.

4. A high optical quality Ho according to claim 1₂Zr₂O₇The preparation method of the magneto-optical ceramic is characterized by comprising the following steps: in the step (2), the concentration of the cesium chloride solution is 0.01 mol/L-0.05 mol/L.

5. A method as claimed in claim 1High optical quality Ho₂Zr₂O₇The preparation method of the magneto-optical ceramic is characterized by comprising the following steps: in the step (2), the doping amount of the cesium chloride solution is controlled by a metering pump, and the doping amount is controlled to be 0.1-0.5% of the total amount of the cationic substances.

6. A high optical quality Ho according to claim 1₂Zr₂O₇The preparation method of the magneto-optical ceramic is characterized by comprising the following steps: in the step (2), the roasting temperature is 400-900 ℃.

7. A high optical quality Ho according to claim 1₂Zr₂O₇The preparation method of the magneto-optical ceramic is characterized by comprising the following steps: in the step (3), under the condition of oxygen with the concentration of 99.99 percent and the flow rate of 100mL/min, the calcining temperature of the intermediate product is 1000-1400 ℃, and the calcining time is 1-6 h.

8. A high optical quality Ho according to claim 1₂Zr₂O₇The preparation method of the magneto-optical ceramic is characterized by comprising the following steps: in the step (4), the pressure is 100 MPa-400 MPa during cold isostatic pressing.

9. A high optical quality Ho according to claim 1₂Zr₂O₇The preparation method of the magneto-optical ceramic is characterized by comprising the following steps: in the step (4), the sintering temperature is 1600-2000 ℃, the sintering time is 2-6 h, and the vacuum degree is 10^-4Pa～10^-5Pa。

10. A high optical quality Ho according to claim 1₂Zr₂O₇The preparation method of the magneto-optical ceramic is characterized by comprising the following steps: in the step (4), when annealing is carried out in an oxygen atmosphere with the concentration of 99.99% and the flow rate of 100mL/min, the temperature is 1100-1700 ℃, and the annealing time is 2-6 h.