CN108017390B

CN108017390B - Rare earth doping-based lead-free ferroelectric photochromic material and preparation method and application thereof

Info

Publication number: CN108017390B
Application number: CN201711305680.8A
Authority: CN
Inventors: 罗来慧; 章园园
Original assignee: Ningbo University
Current assignee: Dongying Ruigang Investment Service Co ltd
Priority date: 2017-12-11
Filing date: 2017-12-11
Publication date: 2021-02-23
Anticipated expiration: 2037-12-11
Also published as: CN108017390A

Abstract

The invention relates to a lead-free ferroelectric photochromic material, which comprises (K)_0.5Na_0.5)NbO₃The lead-free ferroelectric ceramic material as the matrix is characterized in that: the chemical formula of the lead-free ferroelectric ceramic material is (K)_0.5Na_0.5)_0.998‑xEr_0.002Yb_xNbO₃Wherein x is more than or equal to 0.002 and less than or equal to 0.008, and a rare earth element sensitizer Yb is added at the A site³⁺And rare earth element activated Er³⁺Substituted K⁺And Na⁺Ions, and further up-conversion luminescence of the material is realized, and compared with the prior art, the invention has the following advantages: the lead-free ferroelectric photochromic material has the advantages that the cost of raw materials for preparing the base material is low, the fatigue resistance of the photochromic material is good, and the color change degree of the inorganic photochromic material can be effectively adjusted to a certain extent by the co-doping of the rare earth elements so as to meet the requirements of different applications.

Description

Rare earth doping-based lead-free ferroelectric photochromic material and preparation method and application thereof

Technical Field

The invention relates to a ferroelectric photochromic material, and also discloses a preparation method and application of the ferroelectric photochromic material.

Background

Photochromic materials are materials that change color when excited by a light source. The traditional photochromic material mainly comprises tungsten oxide, bromide and some organic matters. Conventional photochromic materials change color by primarily using the phase change of a light irradiation material. Potassium sodium niobate (K)_0.5Na_0.5)NbO₃The ceramic material has excellent piezoelectric, ferroelectric, dielectric, electrooptical and other electrical properties, and is one excellent lead-free ferroelectric material.

Recently, the application and research of preparing the up-conversion luminescent material by using the lead-free ferroelectric material doped with the rare earth element are more and more, and related documents are listed in the Chinese invention patent 'a potassium sodium niobate based oxide up-conversion luminescent material and a preparation method thereof' (the publication number is CN101544886B) with the patent number of ZL201310182740.7, and also can refer to the Chinese invention patent 'a halophosphate reversible photochromic material and a preparation method thereof' (the publication number is CN104403659B) with the patent number of ZL 201410622062.6; has potential application value in the modern electronic industry and the optical field.

Due to (K)_0.5Na_0.5)NbO₃The volatilization of K and Na ions during the high-temperature sintering of the ceramic can form a plurality of inherent point defects in the ceramic, such as oxygen vacancies, A/B site vacancies, excitons and the like. These defects can have a significant impact on the electrical and optical properties of the material. Due to the existence of the defect, a defect energy level is introduced between a conduction band and a valence band of the material, so that (K)_0.5Na_0.5)NbO₃Becoming a potential photochromic material. With the wider application range of the current photochromic materials and the higher requirement on the multifunctionality of the materials, the traditional materials can not meet the application requirements of some special occasions. The traditional photochromic material lacks the piezoelectric and pyroelectric effects of ferroelectric materials, thus greatly limiting the wide application of the photochromic material. With the development of semiconductor technology, 980nm semiconductor laser can be obtained at low cost at present, and trivalent rare earth ion Yb is utilized³⁺Strongly absorb 980nm laser and then transfer the absorbed photon energy to other rare earth ions such as Pr³⁺，Er³⁺，Tm³ ⁺Fluorescence visible to the naked eye can be obtained. The photochromic material of ferroelectric substance reported at present is mainly Na_0.5Bi_2.5Nb₂O₉(ACS appl. Mater. interfaces 2016,8,4789-4794), but the restoration of photochromic of the material can only be realized by heating, and the heating of the material cannot easily realize the real-time regulation and control of the luminescence of the material.

Disclosure of Invention

The invention aims to solve the technical problem of providing a lead-free ferroelectric photochromic material which is easy to realize real-time regulation and control of material luminescence aiming at the current situation of the prior art.

The invention aims to solve another technical problem of providing a preparation method of the lead-free ferroelectric photochromic material with lower production cost aiming at the current situation of the prior art.

The invention also provides an application of the lead-free ferroelectric photochromic material, aiming at the current state of the prior art.

The technical scheme adopted by the invention for solving the technical problems is as follows: the lead-free ferroelectric photochromic material comprises (K)_0.5Na_0.5)NbO₃The lead-free ferroelectric ceramic material as the matrix is characterized in that: the chemical formula of the lead-free ferroelectric ceramic material is (K)_0.5Na_0.5)_0.998-xEr_0.002Yb_xNbO₃Wherein x is more than or equal to 0.002 and less than or equal to 0.008, and a rare earth element sensitizer Yb is added at the A site³⁺And rare earth element activated Er³⁺Substituted K⁺And Na⁺Ions, and then up-conversion luminescence of the material is realized.

The invention provides a preparation method of a lead-free ferroelectric photochromic material for solving a second technical problem, which is characterized by comprising the following steps:

(1) according to the chemical general formula (K) of the potassium sodium niobate based oxide up-conversion luminescent material_0.5Na_0.5)_0.998- _xEr_0.002Yb_xNbO₃The following raw materials are weighed according to the stoichiometric ratio of K, Na, Yb, Er and Nb: k₂CO₃、Na₂CO₃、Nb₂O₅、Er₂O₃And Yb₂O₃Wherein the value of x is 0.002-0.008; then putting the mixture into a ball milling tank for ball milling and mixing, putting the ball milled raw materials into an oven for drying, tabletting the dried raw materials by using a tablet machine under the pressure of 5-80 MPa, putting the pressed green blank into a muffle furnace, preserving heat at the temperature of 750-850 ℃ for 1-3 hours, and synthesizing (K)_0.5Na_0.5)_0.998-xEr_0.002Yb_xNbO₃Powder;

(2) crushing the blank obtained in the step (1), putting the crushed blank into a ball milling tank for ball milling for 5-10 hours, and putting the milled blank into an oven for drying;

(3) adding the dried powder obtained in the step (2) into a polyvinyl alcohol aqueous solution with the mass concentration of 3-5% as a binder for granulation, and tabletting and molding the granulated powder under 100-200 MPa; then the embryo body is put inPutting the ceramic wafer into a muffle furnace, preserving heat for 0.5-3 hours at 600-700 ℃ to decompose the binder, then preserving heat for 2-4 hours at 1050-1200 ℃, and finally obtaining the ceramic wafer (K)_0.5Na_0.5)_0.998-xEr_0.002Yb_xNbO₃The lead-free ferroelectric up-conversion fluorescent ceramic material.

Further, the volume of the raw materials in the ball milling mixing in the step (1) is as follows: agate sphere volume: the volume ratio of the ball milling medium absolute ethyl alcohol is 1: (1-1.2): (1-1.5).

The invention also provides application of the lead-free ferroelectric photochromic material in optical storage, optical recording and optical labels.

Compared with the prior art, the invention has the following advantages: the lead-free ferroelectric photochromic material has the advantages that the cost of raw materials for preparing the base material is low, the physical and chemical stability of the product is good, when the ceramic material is irradiated by sunlight, the intensity of visible light emitted by the ceramic is reduced by more than 80% under the excitation of 980nm infrared light, and the luminous intensity and the color can be completely recovered by processing the color of the ceramic after the irradiation by the light and the up-conversion luminous intensity at 200 ℃; and after irradiation with light of 390nm (K)_0.5Na_0.5)_0.998-xEr_0.002Yb_xNbO₃The ceramic is partially restored in color and luminous intensity by applying an electric field to the ceramic, wherein the luminous intensity can reach 2 times (Na) after irradiation_0.5Bi_0.4796Yb_0.02Tm_0.0004TiO₃) The up-conversion fluorescence color of the ceramic is white, the fatigue resistance of the discoloration is good, the color change degree of the inorganic photochromic material can be effectively adjusted to a certain extent through the co-doping of the rare earth elements so as to meet the requirements of different applications, and the photochromic material can be widely applied to the fields of optical information storage and conversion, inductors, anti-counterfeiting, decoration, radiometer and the like.

Drawings

FIG. 1 shows (K) in example 1 of the present invention_0.5Na_0.5)_0.998-xEr_0.002Yb_xNbO₃An X-ray diffraction pattern of the ceramic;

FIG. 2 shows (K) in example 4 of the present invention_0.5Na_0.5)_0.998-xEr_0.002Yb_xNbO₃A result graph of the influence of the ceramic on the up-conversion luminescence intensity after temperature, light irradiation and electric field treatment;

FIG. 3 shows (K) in example 5 of the present invention_0.5Na_0.5)_0.996Er_0.002Yb_0.002NbO₃The up-conversion emission spectra of the ceramic at different irradiation times;

FIG. 4 shows (K) in example 6 of the present invention_0.5Na_0.5)_0.996Er_0.002Yb_0.002NbO₃The upconversion luminescence intensity of the ceramic is related to the light irradiation and the applied electric field.

Detailed Description

The invention is further described by the following embodiments in conjunction with the drawings.

Example 1

Adopts Na with the purity of 99.8 percent₂CO₃99.8% of Na₂CO₃99.8% of TiO₂99.9% Er₂O₃And 99.9% of Yb₂O₃Is prepared from raw materials according to the chemical formula (K)_0.5Na_0.5)_0.998-xEr_0.002Yb_xNbO₃(x is 0.002, 0.004, 0.006, 0.008) and putting into a ball milling pot for mixing and ball milling, wherein the ball milling conditions are as follows: the volume ratio of the raw materials to the volume of the agate balls to the volume of the ball-milling medium absolute ethyl alcohol is approximately equal to 1: 1: 1.5, ball-milling the mixture for 8 hours, and putting the ball-milled raw materials into an oven to be dried for 4 hours at the temperature of 80 ℃. Then, tabletting the dried raw materials into raw material blanks with the diameter of 40mm by a tabletting machine under the pressure of 100Mpa, then putting the pressed blanks into a KBF1400 box type furnace for presintering, preserving the presintering condition for 3 hours at the temperature of 600 ℃ to decompose the binder, then preserving the heat for 4 hours at the temperature of 1050 ℃, grinding the presintering blocky samples into powder, sieving the powder, carrying out ball milling on the powder for 12 hours, and putting the powder into an oven for drying for 4 hours at the temperature of 80 ℃. Finally, the dried powder is added with 1ml of PVA adhesive with the mass concentration of 3 percent according to the proportion of 10g of powderGrinding, granulating, sieving with 80 mesh sieve for 3 times, weighing the ground powder to 0.495 g, pressing into 13mm small pieces under 2MPa, and adding Al₂O₃And (3) laying mother powder on the gasket, covering the pressed small pieces with the mother powder, and sintering the small pieces in a box-type furnace under the sintering condition of 1200 ℃ for 2 hours. Fired ceramic (shown in FIG. 1 as (K)_0.5Na_0.5)_0.998- _xEr_0.002Yb_xNbO₃X-ray diffraction pattern of ceramic) can be seen from the graph (K)_0.5Na_0.5)_0.998-xEr_0.002Yb_xNbO₃The ceramic is of perovskite structure.

Example 2

Adopts Na with the purity of 99.8 percent₂CO₃99.8% of Na₂CO₃99.8% of TiO₂99.9% Er₂O₃And 99.9% of Yb₂O₃Is prepared from raw materials according to the chemical formula (K)_0.5Na_0.5)_0.998-xEr_0.002Yb_xNbO₃(x is 0.002, 0.004, 0.006, 0.008) and putting into a ball milling pot for mixing and ball milling, wherein the ball milling conditions are as follows: the volume ratio of the raw materials to the volume of the agate balls to the volume of the ball-milling medium absolute ethyl alcohol is approximately equal to 1: 1.2: 1, ball-milling the raw materials for 10 hours, and putting the ball-milled raw materials into an oven to be dried for 3 hours at the temperature of 80 ℃. Then, pressing the dried raw materials into raw material blanks with the diameter of 40mm under the pressure of 200Mpa by using a tablet press, then putting the pressed blanks into a KBF1400 box type furnace for presintering, wherein the presintering condition is that the temperature is kept at 700 ℃ for 0.5 hour to decompose a binder, then keeping the temperature at 1200 ℃ for 2 hours, then grinding the presintering block samples into powder, sieving the powder, carrying out ball milling on the powder for 12 hours, and putting the powder into an oven for drying at 80 ℃ for 4 hours. Finally, grinding the dried powder according to the proportion of 10g of powder and 1ml of PVA adhesive with the mass concentration of 5%, granulating, sieving for 3 times by using a 80-mesh sieve, pressing the ground powder into small pieces with the diameter of 15mm under the pressure of 3MPa, and adding Al₂O₃Laying mother powder on the gasket, covering the pressed small pieces with the mother powder, and sintering in a box furnace at 1050 deg.C for 4 hr。

Example 3

Adopts Na with the purity of 99.8 percent₂CO₃99.8% of Na₂CO₃99.8% of TiO₂99.9% Er₂O₃And 99.9% of Yb₂O₃Is prepared from raw materials according to the chemical formula (K)_0.5Na_0.5)_0.998-xEr_0.002Yb_xNbO₃(x is 0.002, 0.004, 0.006, 0.008) and putting into a ball milling pot for mixing and ball milling, wherein the ball milling conditions are as follows: the volume ratio of the raw materials to the volume of the agate balls to the volume of the ball-milling medium absolute ethyl alcohol is approximately equal to 1: 1.1: 1.3, ball-milling the raw materials for 5 hours, and putting the ball-milled raw materials into an oven to be dried for 3 hours at the temperature of 80 ℃. Then, pressing the dried raw materials into raw material blanks with the diameter of 40mm under the pressure of 200Mpa by using a tablet press, then putting the pressed blanks into a KBF1400 box type furnace for presintering, wherein the presintering condition is that the temperature is kept at 700 ℃ for 0.5 hour to decompose a binder, then keeping the temperature at 1200 ℃ for 2 hours, then grinding the presintering block samples into powder, sieving the powder, carrying out ball milling on the powder for 12 hours, and putting the powder into an oven for drying at 80 ℃ for 4 hours. Finally, grinding the dried powder according to the proportion of 10g of powder and 1ml of PVA adhesive with the mass concentration of 5%, granulating, sieving for 3 times by using a 80-mesh sieve, pressing the ground powder into small pieces with the diameter of 15mm under the pressure of 3MPa, and adding Al₂O₃And (3) laying mother powder on the gasket, covering the pressed small pieces with the mother powder, and sintering the small pieces in a box-type furnace under the condition of 1050 ℃ for 4 hours.

Example 4

The fired ceramic of example 1 was subjected to temperature, light irradiation and electric field treatment to perform correlation tests on the up-conversion luminous intensity and the ceramic color emission; from the results of fig. 2, it can be seen that the color change of the ceramic sample is reversible after the ceramic sheet is irradiated by sunlight, heated at 200 degrees, and the electric field intensity is 20kV/cm, and it can be seen from fig. 2 that the color of the ceramic sample is darkened after the sample is irradiated, the color of the sample is restored after the sample is heated, and the color of the sample is lightened after the sample is irradiated by the electric field. The method for applying the electric field to the ceramic sample in the embodiment comprises the following steps: before the electric field is applied, plating a silver electrode on the lower surface of the ceramic sample, sputtering a gold electrode of about 200 nanometers on the upper surface, and applying the electric field to the sample through a high-voltage source; the light irradiation is carried out by using 390nm light emitted by a xenon lamp; if the ceramic plate prepared by laser excitation with the wavelength of 980nm is used, the ceramic can emit strong visible light.

Example 5

The luminous intensity of the ceramic fired in example 1 after being irradiated at 390nm for various times was measured, and the result is shown in fig. 3, the irradiated sample was treated at 200 degrees for 30 minutes, the prepared ceramic sheet was changed from white to gray, and the color of the ceramic was restored to the original white by heating the ceramic after the ceramic irradiation. In addition, 980nm infrared laser is used for irradiation, up-conversion visible fluorescence with different colors including white light is obtained, and the luminous energy of the sample can be recovered; and from the results of fig. 3, it can be seen that the ceramic emits green light at 525 nm and 550 nm, which is attributed to Er³⁺Of rare earth ions²H_11/2→⁴I_15/2,⁴S_3/2→⁴I_15/2The energy level transition results, and furthermore the intensity of the luminescence decreases rapidly with irradiation time.

Example 6

The ceramic obtained by firing the ceramic of example 4 was irradiated with 390nm light and tested for its luminous intensity under the action of electric field, and the result is shown in fig. 4. the ceramic sheet after light irradiation was applied with an electric field of 12.5 kv/cm, the gray level of the ceramic was reduced, and after the time of 60 seconds when the electric field was applied with 12.5 kv/cm, the upconversion luminous intensity of the sample was increased to 120% before irradiation, and there was no significant attenuation after many cycles.

Example 7

After the ceramic fired in the embodiment 1 is irradiated by sunlight or an electric field and is irradiated by 980nm infrared laser, the luminous intensity of the irradiated ceramic is less than 20% of the initial state luminous intensity, and after the irradiated ceramic is subjected to the electric field of 12.5 kilovolts/cm, the luminous intensity is more than 2 times of that of the irradiated sample.

Claims

1. A preparation method of a lead-free ferroelectric photochromic material is characterized by comprising the following steps:

(1) according to the chemical general formula (K) of the potassium sodium niobate based oxide up-conversion luminescent material_0.5Na_0.5)_0.998-xEr_0.002Yb_xNbO₃The following raw materials are weighed according to the stoichiometric ratio of K, Na, Yb, Er and Nb: k₂CO₃、Na₂CO₃、Nb₂O₅、Er₂O₃And Yb₂O₃Wherein x is 0.002, 0.004, 0.006, 0.008), and a rare earth element sensitizer Yb is added at the A position³⁺And rare earth element activated Er³⁺Substituted K⁺And Na⁺Ion, further realizing up-conversion luminescence of the material, then putting the material into a ball milling tank for ball milling and mixing, putting the ball milled raw material into an oven for drying, tabletting the dried raw material at 100MPa by using a tabletting machine, putting the pressed green blank into a muffle furnace, preserving heat at 1050 ℃ for 4 hours, and synthesizing (K)_0.5Na_0.5)_0.998-xEr_0.002Yb_xNbO₃Powder;

(2) crushing the blank obtained in the step (1), putting the crushed blank into a ball milling tank for ball milling for 12 hours, and putting the ball milled blank into an oven for drying;

(3) adding the dried powder obtained in the step (2) into a polyvinyl alcohol aqueous solution with the mass concentration of 3% as a binder for granulation, and tabletting and molding the granulated powder under 2 MPa; then placing the blank into a muffle furnace, preserving the heat at 600 ℃ for 3 hours to decompose the binder, then preserving the heat at 1050 ℃ for 4 hours, and finally obtaining the ceramic wafer (K)_0.5Na_0.5)_0.998-xEr_0.002Yb_xNbO₃The lead-free ferroelectric up-conversion fluorescent ceramic material is characterized in that the color change of a ceramic sample is reversible after a ceramic wafer is irradiated by sunlight, heated at 200 ℃ and has an electric field intensity of 20kV/cm, the color of the sample is darkened after the ceramic sample is irradiated, the sample is recovered after the ceramic sample is heated, and the color of the sample is lightened after the irradiated sample is subjected to an electric field; ceramic wafer at 390nm lightTesting the luminous intensity after different times of irradiation, treating the irradiated sample at 200 ℃ for 30 minutes to convert the prepared ceramic wafer from white to gray, and heating the ceramic after the ceramic irradiation to restore the color of the ceramic to the original white; irradiating by using 980nm infrared laser to obtain up-conversion visible fluorescence with different colors including white light, and recovering the luminous energy of the sample; the ceramic emits green light at 525 nm and 550 nm, which is Er³⁺Of rare earth ions²H_11/2→⁴I_15/2,⁴S_3/2→⁴I_15/2Energy level transitions, and furthermore the intensity of the luminescence decreases very rapidly with irradiation time; the luminous intensity of the ceramic under 390nm light irradiation and electric field effect is tested again, the ceramic wafer after light irradiation is applied with an electric field of 12.5 kilovolts/cm, the gray level of the ceramic is reduced, the up-conversion luminous intensity of the sample can be improved to 120% before irradiation after the time of 12.5 kilovolts/cm application for 60 seconds, and no obvious attenuation exists after multiple cycles; after the ceramic is irradiated by sunlight or an electric field and is irradiated by 980nm infrared laser, the luminous intensity of the irradiated ceramic is less than 20% of the initial state luminous intensity, and after the irradiated ceramic is subjected to the electric field of 12.5 kilovolts/cm, the luminous intensity of the irradiated ceramic is more than 2 times that of the irradiated sample.