CN114686226A

CN114686226A - Electron-trapping rare earth co-doped yttrium germanate optical storage medium and preparation method and application thereof

Info

Publication number: CN114686226A
Application number: CN202011594767.3A
Authority: CN
Inventors: 刘茜; 邓明雪; 徐小科
Original assignee: Shanghai Institute of Ceramics of CAS
Current assignee: Shanghai Institute of Ceramics of CAS
Priority date: 2020-12-29
Filing date: 2020-12-29
Publication date: 2022-07-01

Abstract

The invention relates to an electron capture type rare earth co-doped yttrium germanate optical storage medium and a preparation method and application thereof, wherein the chemical formula of the electron capture type rare earth co-doped yttrium germanate optical storage medium is Y_2‑x‑yGeO₅:xPr³⁺,yRE³⁺Wherein RE = at least one of Tb, Dy, Ho, Er, Tm, Yb and Lu, x is more than 0.005 and less than 0.015, and y is more than 0 and less than or equal to 0.02.

Description

Electron-trapping rare earth co-doped yttrium germanate optical storage medium and preparation method and application thereof

Technical Field

The invention relates to an electron capture type rare earth co-doped yttrium germanate optical storage medium, a preparation method thereof and application thereof in binary optical information storage, belonging to the technical field of optical information storage.

Background

The total amount of data generated globally by 2025 is predicted by international data corporation to reach 175ZB (1 ZB-10)¹²GB), wherein cold data (visit)Less frequently asked but important data, such as city statistics, hospital patient health data, national defense confidentiality data, etc.) account for about 80%. Optical information storage is considered to be the most promising cold data storage method with the advantages of low energy consumption, long lifetime and high security. However, the existing optical storage technologies (such as CD, DVD or BD) are subject to the optical diffraction limit and two-dimensional storage mode, and the capacity is difficult to meet. At present, commercial optical storage media mainly comprise optothermal plastics, photorefractive crystals and photopolymers, and have the problems of easy aging and failure, so that the development of a novel durable super-resolution recording material is urgently needed.

The rare earth doped electron capture type luminescent material is a special member in an advanced optical material family, the material can absorb X-ray or high-energy ultraviolet energy, a part of carriers (usually rare earth luminescent ions) are excited to emit light, namely 'information writing', and the wave band is a 'writing' wave band; the other part of the carriers enter the trap (energy storage trap) after being excited and are stored, the trapped carriers are stabilized in the trap, and then the light with longer wavelength is used for exciting the material, so that the trapped carriers in the trap can be released, and then the recombination of electrons and holes is realized, and the light excitation luminescence is formed, wherein the waveband is a 'readout' waveband, namely, the information can be read out under a certain light excitation condition. The novel optical storage material can replace the traditional dye and phase-change material as a recording medium, so that the optical storage writing mechanism is changed into the optical quantum effect with higher speed from the currently adopted photo-thermal effect with slower reaction, the information writing energy consumption is reduced, and the data writing speed is improved. The optical disk storage can extend from the current two-dimensional plane to the multi-dimensional space, and extends from holographic storage to multi-dimensional storage, so that the storage density is greatly improved. However, the real realization of fast-response and high-density optical information storage still faces a plurality of problems.

Firstly, in the rare earth doped electron trapping type luminescent material, the existence of defect energy level is the basis; secondly, efficient regulation of the defect levels is critical to ensure that the mechanism of optical information writing and reading can take place. From the point of view of band engineering analysis, by doping with non-luminescent rare earth ions or transition metal ions having a rich electronic structureUnder the synergistic effect, a local trap energy level is introduced into a matrix forbidden band, and the stimulated transition carriers in the energy band are intercepted or bound. The number of energy-carrying particles bound in a trap is related to the number and depth of energy levels: the more and deeper the trap level is, the larger the carrier storage amount is, which restricts the number of times the optical information can be read and the stability. Currently available relatively effective electron trapping type optical information storage material SrAl₂Si₂O₈:Eu²⁺,Tm³⁺、SrSi₂O₂N₂:Eu²⁺,Tm³⁺、Y₃Al_5-xGa_xO₁₂:Ce³⁺,V³⁺、Ba₂SiO₄:Eu²⁺And LiGa₅O₈:Mn²⁺And the like. However, these inorganic electron trapping materials are also limited to laboratory studies as candidate materials for optical information storage media, and can demonstrate only the phenomenon of writing/reading of optical information on a macroscopic scale (see literature Chemical Engineering journal.2020,392,124807 and Advanced Functional materials.2018,28,1705769.). So far, the writing and reading of optical information points with submicron or even smaller scale which is close to the real scene is not really realized on the microscopic scale, and the distance from the material practical application is still far.

Disclosure of Invention

In order to overcome the limitations of the existing materials and technologies, the invention aims to provide an electron-trapping rare earth co-doped yttrium germanate optical storage medium and a preparation method thereof, so as to realize binary optical information storage of submicron information points.

In a first aspect, the invention provides an electron-trapping type rare earth co-doped yttrium germanate optical storage medium, wherein the chemical formula of the electron-trapping type rare earth co-doped yttrium germanate optical storage medium is Y_2-x-yGeO₅:xPr³⁺,yRE³⁺Wherein RE is at least one of Tb, Dy, Ho, Er, Tm, Yb and Lu, x is more than 0.005 and less than 0.015, and y is more than 0 and less than or equal to 0.02.

In the disclosure, the electron-trapping rare earth co-doped yttrium germanate optical storage medium has good photoluminescence performance and a certain trap energy level (namely a thermoluminescence peak), and photoluminescence can provide detection signals for optical information writing and reading. After optical information is written, carriers are trapped by trap levels, and the trap levels provide an effective energy barrier and a mechanism for resisting thermal disturbance at room temperature for storing optical information, namely, the carriers are difficult to trap at room temperature.

Preferably, x is 0.01, y is 0.001, and Re is Tb. Where x is 0.01 and y is 0.001, the present inventors repeatedly screened the obtained material components. The optical storage medium prepared by the composition shows a characteristic emission peak of praseodymium under the excitation of ultraviolet light, namely multicolor emission peaks taking 492, 536, 551, 611, 621, 653 and 740nm as centers, the range is from blue green to near infrared red, and the characteristic emission peaks respectively correspond to P^r3+Excited electrons in ions from³P₀To³H₄、³P₀/³P₁To³H₅、¹D₂To³H₄、³P₀To³H₆/³F₂And³P₀to³F₄The 7 f-f energy level transitions have good multi-band photoluminescence performance; and the pyroelectric optical film has triple discrete pyroelectric optical peaks which are respectively positioned at 355K, 431K and 525K on the temperature coordinate axis, and can provide an effective energy barrier and a mechanism for resisting room temperature thermal disturbance for storing optical information.

Preferably, the electron-trapping type rare earth co-doped yttrium germanate optical storage medium is an electron-trapping type rare earth co-doped yttrium germanate powder optical storage medium or an electron-trapping type rare earth co-doped yttrium germanate ceramic optical storage medium.

Preferably, the optical excitation is performed under ultraviolet light (meaning conventional ultraviolet light or continuous laser light of ultraviolet band) having a wavelength of 200nm to 270nm (e.g., 254nm) or femtosecond laser light having a wavelength of 400nm to 540nm (e.g., 515nm) to efficiently write optical information in the electron trapping type rare earth co-doped yttrium germanate optical storage medium;

the optical excitation is performed under thermal excitation at a temperature higher than 100 ℃ (e.g., 250 ℃) or under laser (here, the laser can be femtosecond laser or continuous laser) with the wavelength ranging from 400nm to 1250nm (e.g., 515nm, 650nm, 808nm, 980nm, etc.) to realize one or more readouts of optical information in the electron trapping type rare earth co-doped yttrium germanate optical storage medium.

In a second aspect, the invention further provides a preparation method of the electron-trapping rare earth co-doped yttrium germanate optical storage medium, which includes:

(1) weighing and mixing a Y source, a Ge source, a Pr source and a RE source serving as raw materials according to a stoichiometric ratio, and performing presintering treatment to obtain presintering powder;

(2) sintering the obtained pre-sintering powder to obtain the electron capture type rare earth co-doped yttrium germanate optical storage medium;

preferably, the Y source is Y₂O₃(ii) a The Ge source is GeO₂(ii) a The Pr source is Pr₆O₁₁(ii) a The RE source is Tb₄O₇、Dy₂O₃、Ho₂O₃、Er₂O₃、Tm₂O₃、Yb₂O₃And Lu₂O₃At least one of (1).

Preferably, the temperature of the pre-sintering treatment is 600-1000 ℃, and the time is 1.5-5 hours; the sintering synthesis temperature is 1100-1700 ℃, and the time is 3-10 hours;

preferably, the presintered powder is pressed and molded and then sintered; more preferably, the calcined powder and the binder are mixed and then press-molded and sintered.

In a third aspect, the invention provides an electron-trapping rare earth co-doped yttrium germanate ceramic optical storage medium, which is prepared by mixing (for example, primary ball milling) pre-sintered powder of the electron-trapping rare earth co-doped yttrium germanate optical storage medium with a binder, drying (preferably, drying and then grinding again), press-molding, and calcining at 600-1000 ℃ for 1.5-4 hours (removing the binder).

In a fourth aspect, the present invention provides an electron-trapping rare earth co-doped yttrium germanate optical storage medium film, comprising: transparent high molecular material is used as a substrate, and electron capture type rare earth co-doped yttrium germanate optical storage medium powder is distributed in the substrate; the content of the electron capture type rare earth co-doped yttrium germanate optical storage medium powder is 10-50 wt%.

Preferably, the particle size of the electron capture type rare earth co-doped yttrium germanate optical storage medium powder is 50 nm-2 μm.

Preferably, the thickness of the electron-trapping rare earth co-doped yttrium germanate optical storage medium film is at least 500 nm.

Preferably, the optical information is written in and read out from the electron capture type rare earth co-doped yttrium germanate optical storage medium film by performing optical excitation under ultraviolet light with the wavelength of 200 nm-270 nm or femtosecond laser with the wavelength of 400 nm-540 nm and moving the film-carrying sample stage at a constant speed in an x-y plane.

In a fifth aspect, the present invention provides an application of an electron-trapping type rare earth co-doped yttrium germanate ceramic optical storage medium or an electron-trapping type rare earth co-doped yttrium germanate optical storage medium thin film in binary optical information storage, including:

(1) writing in submicron-scale optical information points on different positions in an electron capture type rare earth co-doped yttrium germanate ceramic optical storage medium and an electron capture type rare earth co-doped yttrium germanate optical storage medium film by adopting an ultraviolet beam with the wavelength of 200 nm-270 nm or a focused femtosecond laser beam with the wavelength of 400 nm-540 nm;

(2) the method comprises the following steps of performing linear continuous scanning on an electron capture type rare earth co-doped yttrium germanate ceramic optical storage medium or an electron capture type rare earth co-doped yttrium germanate optical storage medium film for writing optical information by using a laser with a wavelength of 400 nm-1250 nm (the laser can be a femtosecond laser or a continuous laser, for example, the femtosecond laser with a wavelength of 515nm, 650nm, 808nm or 980nm, or the continuous laser with a wavelength of 515nm, 650nm, 808nm or 980nm), and representing two states of '0' and '1' in binary information by recording two different states of 'non-luminescence' and 'luminescence' in the scanning direction; wherein the diameter of the ultraviolet light beam or the focused femtosecond laser beam is 10 nm-2 μm.

Has the advantages that:

(1) in the invention, the inorganic electron capture type material rare earth co-doped yttrium germanate medium has good photoluminescence performance and triple discrete thermoluminescence peaks in a wider temperature range, and provides an effective energy barrier and a mechanism for resisting room temperature thermal disturbance for storing optical information;

(2) the invention realizes the writing and reading of submicron-scale optical information points on the inorganic electron capture type rare earth co-doped yttrium germanate film for the first time, realizes the recording of binary information change in a spectrum mode, and promotes the practical progress of the electron capture type optical information storage material;

(3) the invention can promote the practical application process of the inorganic electron capture type material with excellent chemical stability in long service life, safe storage, high density and ultrahigh speed optical information storage; if the thickness of the film, the ceramic pressing sheet or the ceramic is increased, three-dimensional optical information storage can be realized by adjusting the position of the laser beam, and the method has wide application prospect.

Drawings

FIG. 1 shows the rare earth co-doped yttrium germanate Y in example 1_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺X-ray diffraction pattern (XRD) of the powder with Y inserted at the bottom₂GeO₅Standard X-ray diffraction spectra of the main crystalline phase;

FIG. 2 shows the rare earth co-doped yttrium germanate Y in example 1_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺Photoluminescence emission (PL) and excitation (PLE) spectra of the powder;

FIG. 3 shows the rare earth co-doped yttrium germanate Y in example 1_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺The thermoluminescent spectrum (TL) of the powder;

FIG. 4 shows the rare earth co-doped yttrium germanate Y in example 1_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺Information retention rate curve of the powder;

FIG. 5 shows the rare earth co-doped yttrium germanate Y in example 2_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺Reading the characterization result of the optical information of the ceramic pressing sheet for multiple times;

FIG. 6 shows the rare earth co-doped yttrium germanate Y in example 2_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺Mask "F" for use in ceramic preform"demonstration result of macroscopically simulating optical information storage;

FIG. 7 shows the co-doping of yttrium germanate Y with rare earth in example 3_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺The film is prepared by polyvinylpyrrolidone (PVP), so that a binary optical storage demonstration result of writing and reading of submicron-order optical information points can be realized by a micro-scale simulation optical disc;

FIG. 8 shows the rare earth co-doped yttrium germanate Y in example 4_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺A picture of the ceramic;

FIG. 9 shows the rare earth co-doped yttrium germanate Y in example 4_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺Photoluminescence spectrogram of the ceramic under 245nm excitation;

FIG. 10 shows the rare earth co-doped yttrium germanate Y in example 4_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺A thermoluminescent spectrum of the ceramic;

FIG. 11 shows the rare earth co-doped yttrium germanate Y with different Tb concentrations in examples 5-8_1.99-yGeO₅:0.01Pr³⁺,yTb³⁺The thermoluminescent spectrum of (c);

FIG. 12 shows different RE ions RE and RE co-doped Yttrium germanate Y in example 9_1.989GeO₅:0.01Pr³⁺,yRE³⁺A pyroelectric spectrum of the optical storage powder, wherein RE is at least one of Dy, Ho, Er, Tm, Yb and Lu;

FIG. 13 shows the rare earth co-doped yttrium germanate Y in example 9_1.989GeO₅:0.01Pr³⁺,0.001Dy³⁺Powder information retention rate;

FIG. 14 shows the rare earth co-doped yttrium germanate optical storage medium Y in comparative examples 1 and 2_2-x-yGeO₅:xPr³⁺,yRE³⁺Where x is 0.01, Y is 0 and x is 0, Y is 0.001, and RE Tb and rare earth co-doped yttrium germanate Y_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺The spectrum of thermoluminescent light of (1).

Detailed Description

The present invention is further illustrated by the following examples, which are to be understood as merely illustrative and not restrictive.

In the present disclosure, the electron-trapping rare earth co-doped yttrium germanate optical storage medium has the chemical formula Y_2-x-yGeO₅:xPr³⁺,yRE³⁺RE is Tb, Dy, Ho, Er, Tm, Yb and Lu, x is more than or equal to 0.005 and less than or equal to 0.015, and y is more than or equal to 0.001 and less than or equal to 0.02. Preferably, x is 0.01. Preferably, 0.001. ltoreq. y.ltoreq.0.01, more preferably 0.001. ltoreq. y.ltoreq.0.005, most preferably y 0.001.

In the disclosure, the rare earth co-doped yttrium germanate optical storage medium shows a characteristic emission peak of praseodymium under the excitation of ultraviolet light, and has better optical storage characteristics. The optical information can be optically excited by 200-270 nm ultraviolet light or femtosecond laser with the wavelength of 400-540 nm so as to effectively write the optical information in the electron capture type rare earth co-doped yttrium germanate optical storage medium. Thermally exciting at the temperature higher than 100 ℃ or optically exciting with laser with the wavelength range of 400-1250 nm (such as 515nm, 650nm, 808nm and 980nm) to realize one-time or multiple-time reading of optical information in the electron capture type rare earth co-doped yttrium germanate optical storage medium. In the present invention, although the femtosecond laser has a time interval, the time interval is very short, and it can read out optical information in the same wavelength range as the continuous laser, and is not substantially affected by the time interval. The frequency of the femtosecond laser can be 30-50 MHz. The pulse width of the femtosecond laser can be 400-600 fs.

In one embodiment of the present invention, the electron-trapping rare earth co-doped yttrium germanate optical storage medium may be in the form of a ceramic block, a ceramic wafer (powder sheet), or a powder. Wherein the particle size of the powder can be 50 nm-2 μm. Wherein, the thickness of the ceramic chip can be 100 μm-10 mm, which can realize the writing and reading of submicron level optical information points. The preparation method of the electron-trapping rare earth co-doped yttrium germanate optical storage medium is exemplarily described below.

And (4) preparing the pre-sintering powder. Weighing Y according to stoichiometric ratio₂O₃、GeO₂、Pr₆O₁₁、Re₂O₃The raw material powder is ground in a mortar for 0.5 to 2 hours to be uniformly mixed, thereby obtaining a mixed powder.Then the mixed powder is presintered (the presintering temperature is preferably within the range of 600-1000 ℃ C., and the heat preservation time is preferably within the range of 1.5-4 hours) to obtain presintered powder, and the aim of the presintering powder is to increase the reaction activity of the powder. Preferably, the raw material powder may be press-molded before the pre-firing treatment. More preferably, the compression molding can be dry compression molding or/and cold isostatic pressing. Most preferably, the second polishing treatment is performed after the pre-firing is completed, and the time is preferably 0.5 to 2 hours.

And directly sintering the pre-sintered powder to obtain the electron capture type rare earth co-doped yttrium germanate optical storage medium (or called electron capture type rare earth co-doped yttrium germanate powder optical storage medium) in the form of powder. Wherein the sintering temperature is preferably 1100-1500 ℃, and the heat preservation time is preferably 3-8 hours.

In an embodiment of the present invention, the pre-sintered powder is pressed and molded to obtain a green body, and then sintered to obtain an electron-trapping rare earth co-doped yttrium germanate optical storage medium (or called an electron-trapping rare earth co-doped yttrium germanate ceramic optical storage medium) in a ceramic block or ceramic wafer form. Wherein, the pressing forming mode can be dry pressing forming or/and cold isostatic pressing forming, etc. More preferably, a quantity of binder is also added to the biscuit. The binder can be polyvinyl alcohol, polyethylene glycol and the like, and the adding amount of the binder can be 1-10 wt% of the mass of the pre-sintered powder.

In one embodiment of the present invention, the electron-trapping rare-earth co-doped yttrium germanate optical storage medium in powder form and the binder may be directly mixed, dried at 50 to 200 ℃, ground again, pressed, and then calcined (mainly for removing the binder and sintering into blocks) at 600 to 1000 ℃ for 1.5 to 4 hours to form tablets (powder tablets) of the electron-trapping rare-earth co-doped yttrium germanate optical storage medium powder. The binder can be polyvinyl alcohol, polyethylene glycol and the like, and the adding amount of the binder can be 1-10 wt% of the mass of the electron capture type rare earth co-doped yttrium germanate powder optical storage medium.

In one embodiment of the invention, the electron capture type rare earth co-doped yttrium germanate optical storage medium in a powder form and the optical polymer material are mixed to prepare a polymer film, and then the writing and reading of the submicron-level optical information points can be realized. The optical polymer material comprises polyvinylpyrrolidone PVP, epoxy resin, polydimethylsiloxane and the like. The addition amount of the electron capture type rare earth co-doped yttrium germanate optical storage medium in the powder form can be 10-50 wt%. The thickness of the resulting polymer film may be 500nm to 1 mm.

The following exemplarily illustrates a method for preparing a polymer film.

Dispersing a certain amount of electron capture type rare earth co-doped yttrium germanate optical storage medium in a powder form into an organic solution (the solvent can be ethanol, cyclohexane and the like) of a transparent high polymer material, and stirring and mixing uniformly to obtain a colloid. And then uniformly coating the colloid on a substrate, and placing the substrate in an oven to keep the temperature of 80-120 ℃ for 20-60 minutes to obtain the optical storage medium for simulating the writing/reading of the information of the optical disk.

In an embodiment of the invention, the polymer film or the rare earth co-doped yttrium germanate ceramic wafer containing the rare earth co-doped yttrium germanate powder is adopted, preferably, focused femtosecond laser beams (the diameter can be 10 nm-2 μm) with the wavelength of 400 nm-540 nm are used for optical excitation, and the writing and reading of the submicron-scale optical information points on the two-dimensional plane of the polymer film sample can be realized by combining the movement (constant speed or variable speed) of the movable film-carrying sample stage on the x-y plane (horizontal plane). When writing, the wavelength of the focused femtosecond laser beam is preferably 515 nm. The read-out can be performed by a laser (femtosecond laser or continuous laser) having a wavelength of 400nm to 1250 nm. Preferably, the laser used is a femtosecond laser, and more preferably, the wavelength may be 515nm, 650nm, 808nm, 980nm, or the like.

As a detailed example, an array of optical information spots (e.g. { 10X 10}) was first automatically recorded in a bit-by-bit scanning mode using a 515nm femtosecond laser beam on the plane of a polymer film (ceramic sheet or ceramic preform). After that, all the written optical information spots are read out by linear continuous scanning of the femtosecond laser preferably to read out the optical information. The emission spectra of the optical information points in the linear scanning area and the interval between the two optical information points are detected in real time, and the states of '0' and '1' in the binary information storage are realized through two differentiated states of 'no light emission' and 'light emission'.

The present invention will be described in detail by way of examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that certain insubstantial modifications and adaptations of the invention by those skilled in the art may be made in light of the above teachings. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below. In the following examples and comparative examples, parameters of the femtosecond laser or the focused femtosecond laser beam used include, unless otherwise specified: the frequency is 40MHz, and the pulse width is 500 fs.

Example 1: rare earth co-doped yttrium germanate Y_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺Powder preparation and spectral characteristics thereof:

(1) according to the molar ratio of the elements Y to Ge to Pr to Tb of 0.989 to 1 to 0.01 to 0.001, yttrium oxide, germanium oxide, hexapraseodymium undecanoxide and tetraterbium heptaoxide are selected as raw materials, and 1.4678g, 0.6800g, 0.0110g and 0.0012g are respectively weighed. Fully grinding the mixture in an agate mortar for 1 hour, and uniformly mixing the mixture to obtain mixed powder;

(2) putting the mixed powder into a muffle furnace, heating from room temperature to 800 ℃ at the heating rate of 5 ℃/min, pretreating for 2h in the air atmosphere, and cooling to obtain pre-sintered powder;

(3) grinding the pre-sintered powder again, putting the ground powder into a muffle furnace, heating the ground powder to the calcination temperature of 1200 ℃ from room temperature according to the heating rate of 3 ℃/min, calcining the ground powder for 5 hours in the air atmosphere, and cooling the calcined powder to the room temperature along with the furnace to obtain the rare earth co-doped yttrium germanate Y_1.989GeO₅:0.01Pr³ ⁺,0.001Tb³⁺And (3) powder. The crystallinity of the synthesized powder is high, as shown in XRD diffraction phase analysis result of figure 1, XRD diffraction peak and Y of the synthesized powder₂GeO₅The standard diffraction peaks of the main crystal phase correspond well.

FIG. 2 shows Y_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺Photoluminescent emission of powdersA spectrogram (excitation wavelength: λ ex ═ 245nm) and an excitation spectrogram (monitoring wavelength: λ em ═ 492 nm). The emission spectrum shows polychromatic emission peaks centered at 492, 536, 551, 611, 621, 653, and 740nm, ranging from blue-green to near-infrared red. They correspond to Pr³⁺In the stimulated emission of electrons from³P₀To³H₄、³P₀/³P₁To³H₅、¹D₂To³H₄、³P₀To³H₆/³F₂And³P₀to³F₄7 f-f energy level transition states. At the same time, the excitation spectrum shows a response to Pr centered at 245nm³⁺4f-4f transition. Description of Y_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺The powder has good photoluminescence performance and the characteristic of realizing information writing by ultraviolet excitation.

FIG. 3 shows Y_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺The Thermoluminescence (TL) spectrum of the powder shows three independent peaks which are respectively positioned at 355K, 431K and 525K on the temperature coordinate axis and can be converted into energy units by calculation, namely the depths of trap energy levels are respectively 0.69eV, 0.93eV and 1.21 eV. These trap levels can effectively trap carriers, thereby providing an energy barrier for storing optical information and resisting thermal perturbations at room temperature. The trap level plays a crucial role in the electron trapping material. The determination of the trap depth and the trap density has a great influence on the process of trapping and de-trapping carriers.

FIG. 4 shows Y_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺And (3) a powder information retention rate curve to show the optical storage performance of the triple deep trap energy levels. FIG. 4a shows Y_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺The TL curves of the bare powder after being irradiated by a 254nm mercury lamp for 100 seconds for different time (10 minutes to 7 days) are reduced in intensity as the static state placing time is increased. The peak intensity and the standing time as a function (FIG. 4b) were used to characterize the information retention. From a trend graphIt can be seen that the peak of thermoluminescence T₁The decay was fastest and almost completely disappeared after 7 days at room temperature. And T₂And T₃The peak intensity is still more than 50% of the original intensity, the good information retention rate is shown, and higher activation energy is needed to stimulate the trapped carriers to be released, so that the deep trap is more favorable for long-term storage of information.

Example 2: rare earth co-doped yttrium germanate Y_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺Powder preforming combines to cover letter "F" mask, realizes the demonstration of macro sightseeing information write in and read out the phenomenon:

0.3g of the rare earth co-doped yttrium germanate Y prepared in example 1 was weighed out_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺Dripping 4 drops of 8% polyvinyl alcohol aqueous solution binder into powder, grinding the powder into sand in an agate mortar, placing the sand in an oven at 80 ℃ for drying for 2h, grinding the sand for 5min again, pouring the powder into a circular tabletting mold with the diameter of 10mm, setting the pressure of 8MPa for 3min, taking the powder out of the mold, placing the powder in a muffle furnace, heating from room temperature to 600 ℃ at the heating rate of 3 ℃/min, calcining for 2h in air atmosphere, removing organic matters, and cooling the powder to room temperature along with the furnace to obtain the rare earth co-doped yttrium germanate Y_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺Powder pressed tablet samples.

FIG. 5 is a rare earth co-doped yttrium germanate Y_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺The powder sheet can realize the condition of reading optical information for many times. After the powder pressing piece is excited for 5min by 254nm ultraviolet light (optical information is written in), detecting a powder pressing piece luminescence attenuation curve, intermittently exciting a powder sample by using a 980nm laser beam (the period is 3 minutes), finding that the luminous intensity of the sample is increased rapidly (optical information is read out) when the 980nm laser is excited, turning off a laser, recovering the intensity to 0, and still keeping a certain light excitation luminous intensity after 5 times of periodic switching, which shows that rare earth co-doped yttrium germanate Y is doped with yttrium germanate_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺Multiple readouts of the optical information can be achieved. The inset is a photograph of the luminescence of the powder sample under excitation by a 980nm laser beam.

FIG. 6 shows the use of a mask with alphabetical information "F" to cover on a rare earth co-doped yttrium germanate Y_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺The powder is subjected to 'macroscopic' simulation of optical information writing and reading. The sheet is exposed through the "F" openings of the mask and emits light under the irradiation of ultraviolet light, so that information F is written on the sheet, as shown in a in fig. 6. Removing the mask, closing the ultraviolet light, placing the powder sheet on a 250 ℃ hot table, and displaying the written information F again in the form of a luminous pattern in a thermal excitation mode, namely reading out the optical information. In FIG. 6, b shows a photograph of the powder in each state, (i) is a photograph of the powder in natural light; when excited by 254nm ultraviolet light, photoluminescence (ii) with light orange color (a mixture of green and red) is generated, i.e. optical information F is immediately written on the surface of the sample piece; and the written information is invisible at room temperature (iii); when thermally excited at 250 ℃, a red emission (iv) is produced, enabling the readout of optical information.

Example 3: rare earth co-doped yttrium germanate Y_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺Film preparation and writing and reading demonstration of submicron scale binary optical information points:

rare earth co-doped yttrium germanate Y_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺The example of the-PVP film (YGO: Pr, Tb-PVP film) is illustrated, but this should not be understood as being limited to PVP films, and other optically transparent polymer materials with better thermal stability and Y may be used_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺Mixing the powder to prepare the membrane.

0.25g of rare earth co-doped yttrium germanate Y_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺Dispersing the powder into 10% PVP ethanol solution, stirring and mixing uniformly to obtain colloid, spin-coating the colloid on a quartz substrate, placing the quartz substrate in an oven, and keeping the temperature at 80-100 ℃ for 30min to obtain the storage medium suitable for carrying out microscopic simulation on the optical disk.

Fig. 7 shows a demonstration of a microscopic analog optical disc for achieving writing and reading of sub-micron scale information dot binary optical information. A in FIG. 7Are pictures of a quartz substrate (left) and a YGO: Pr, Tb-PVP film uniformly coated on the substrate. The substrate coated with YGO: Pr and Tb-PVP films is placed on a sample table, the sample table moves in a two-dimensional plane at a controllable constant speed, the moving precision reaches micro-nano magnitude, focused femtosecond laser beams with the wavelength of 515nm are used for two-dimensional controllable scanning in a black square frame area selected by a film sample, and the bit-by-bit writing of {10 multiplied by 10} optical information point arrays is realized, as shown in b in figure 7, wherein bright points (green) are points written by laser, the radius of the information points is about 0.5 mu m (500nm), and the interval between adjacent information points is about 1 mu m. After writing of an information dot, the femtosecond laser mode is switched to linear continuous scanning, and the area where the optical information dot was just written is linearly scanned according to the line (indicated by a gray arrow in fig. 7 c) in which the laser beam originally moved, and the area where information was written shows red light-excited light emission, while the area where the optical information dot was not written shows no light emission. The variation of the luminescent color between the writing point and the reading point is derived from the luminescent ion Pr³⁺Polychromatic emission characteristics from the blue-green to the red-near infrared band (shown in conjunction with the spectrum of fig. 2). The modified spectral signals of the A-B-A-B region (along the gray arrows, i.e. corresponding to the unwritten-unwritten region) are detected by the equipped fiber-optic probe, and the spectral signal of the region A without optical information written is almost 0, while the spectral peak (in the 600-800nm band interval) appears in the region B with optical information written, as shown by the inset in c of FIG. 7, i.e. the written information is successfully converted into the spectral signal, and the information is read out. D in fig. 7 is a graph of the collected spectrum integrated intensity along with the scanning moving distance, and the states of '0' and '1' in the binary optical information are realized through two differentiated states of 'no light emission' and 'light emission', and the YGO: Pr, Tb-PVP membrane material is proved to have the characteristic of realizing optical information storage on a micro scale corresponding to the area A-B-A-B below c in fig. 7.

Example 4:

the preparation process of the electron-trapping rare earth co-doped yttrium germanate optical storage medium in example 4 is as follows, referring to example 1, except that: weighing 0.3g of pre-sintered powder, dripping 2 wt% of 8 wt% polyvinyl alcohol aqueous solution, grinding again, and pressing to form 10MPMaintaining the pressure for 3 minutes, taking out the die, continuously putting the die into a muffle furnace, keeping the temperature at 600 ℃ for 2 hours, removing the binder, sintering the die into blocks, calcining the blocks at 1300 ℃ for 5 hours in the air atmosphere, and cooling the blocks to room temperature along with the furnace to obtain the rare earth co-doped yttrium germanate Y_1.989GeO₅:0.01Pr³⁺,0.001Tb³⁺Ceramic as shown in fig. 8. FIG. 9 is its photoluminescence spectrum at 245nm excitation showing a series of f-f transition characteristic emissions of praseodymium ions. Fig. 10 shows a pyroelectric spectrum thereof, and shows a triplet pyroelectric peak corresponding to the powder.

Example 5:

the preparation process of the electron-trapping rare earth co-doped yttrium germanate optical storage medium in example 5 is as follows, referring to example 1, except that: x is 0.01 and y is 0.005. FIG. 11 shows the pyroelectric spectrum thereof.

Example 6:

the preparation process of the electron-trapping rare earth co-doped yttrium germanate optical storage medium in example 6 is as follows, referring to example 1, except that: x is 0.01 and y is 0.01. FIG. 11 shows the pyroelectric spectrum thereof.

Example 7:

the preparation process of the electron-trapping rare earth co-doped yttrium germanate optical storage medium in example 7 is as follows, referring to example 1, except that: x is 0.01 and y is 0.015. FIG. 11 shows the pyroelectric spectrum thereof.

Example 8:

the preparation process of the electron-trapping rare earth co-doped yttrium germanate optical storage medium in this example 8 is as follows, with reference to example 1, except that: x is 0.01 and y is 0.02. FIG. 11 shows the pyroelectric spectrum thereof.

Example 9:

the preparation process of the electron-trapping rare earth co-doped yttrium germanate optical storage medium in this example 8 is as follows, with reference to example 1, except that: RE is Dy, Ho, Er, Tm, Yb or Lu, respectively. FIG. 12 shows the thermoluminescence spectrograms of different rare earth ion RE co-doped yttrium germanate optical storage powders. FIG. 13 shows Y_1.989GeO₅:0.01Pr³⁺,0.001Dy³⁺And (3) a powder information retention rate curve to show the optical storage performance of the double trap level. In FIG. 13a is shown as Y_1.989GeO₅:0.01Pr³⁺,0.001Dy³⁺The TL curve of the bare powder is placed for different time (1 hour-7 days) after being irradiated for 100 seconds by using a 254nm mercury lamp (ultraviolet light) under the condition of not protecting, and the intensity of the thermoluminescence is integrally reduced along with the increase of the static placing time. As can be seen from b in fig. 13, compared to the thermoluminescent peak at 357K, the 432K peak of the deeper trap decays more slowly, and the peak intensity is still more than 20% of the original intensity after being placed at room temperature for 7 days, which shows a certain information retention rate, and a higher activation energy is required to stimulate the release of the trapped carriers.

Comparative example 1

The preparation process of the electron-trapping rare earth co-doped yttrium germanate optical storage medium in comparative example 1 is as follows, except that: x is 0.01 and y is 0. Fig. 14 shows a thermal release spectrum, and compared with the Pr and Tb co-doped yttrium germanate optical storage medium in example 1, it is found that the Pr single doping has a very weak thermal release peak, i.e. a lower trap level density and a small trap depth, which are not favorable for capturing more carriers, and are not favorable for optical information storage.

Comparative example 2

The preparation process of the electron-trapping rare earth co-doped yttrium germanate optical storage medium in the comparative example 2 is as follows, referring to example 1, except that: x is 0, y is 0.001, and RE is Tb. Fig. 14 shows the thermoluminescence spectrum, compared with the Pr and Tb co-doped yttrium germanate optical storage medium in example 1, Tb single doping has a weaker thermoluminescence peak, i.e. a lower trap level density, which is not favorable for capturing more carriers, which is not favorable for optical information storage.

For an electron trapping type optical information storage material, the larger and deeper the trap level is, the larger the carrier storage amount is, which restricts the number of times optical information can be read and the stability. The thermoluminescent spectrum is an effective means for representing the trap level of the electron trapping type optical information storage material. Compared with the thermoluminescence spectrum in the example 1 of the invention, the samples with different Tb concentrations (y is 0.005, 0.01, 0.015 and 0.02) in the examples 5 to 8 only have single thermoluminescence peaks, and the peak value is 431K; in example 9, different rare earth ion co-doped samples have double thermoluminescent peaks and lower intensityExample 1; in comparative examples 1-2, the rare earth ion single-doped thermoluminescent peak is significantly lower than that of the codoped rare earth ion, and the rare earth ion single-doped thermoluminescent peak has no triple thermoluminescent peak. Therefore, combining the above examples and comparative examples, rare earth ion co-doping with yttrium germanate Y_2-x-yGeO₅：xPr³⁺,yRE³⁺The optical storage device has certain optical storage performance, preferably x is 0.01, y is 0.001, and RE is Tb, and the triple trap level can store more carriers, thereby further improving the stability of optical information storage.

Finally, it must be said here that: the above embodiments are only used for further detailed description of the technical solutions of the present invention, and should not be understood as limiting the scope of the present invention, and the insubstantial modifications and adaptations made by those skilled in the art according to the above descriptions of the present invention are within the scope of the present invention.

Claims

1. The electron-trapping rare earth co-doped yttrium germanate optical storage medium is characterized in that the chemical formula of the electron-trapping rare earth co-doped yttrium germanate optical storage medium is Y_2-x-yGeO₅: xPr³⁺,yRE³⁺Wherein RE = at least one of Tb, Dy, Ho, Er, Tm, Yb and Lu, x is more than 0.005 and less than 0.015, and y is more than 0 and less than or equal to 0.02; preferably x =0.01 and y = 0.001.

2. The electron-trapping type rare-earth-co-doped yttrium germanate optical storage medium according to claim 1, wherein the electron-trapping type rare-earth-co-doped yttrium germanate optical storage medium is an electron-trapping type rare-earth-co-doped yttrium germanate powder optical storage medium or an electron-trapping type rare-earth-co-doped yttrium germanate ceramic optical storage medium.

3. The electron-trapping rare earth co-doped yttrium germanate optical storage medium according to claim 1 or 2, wherein optical excitation is performed under ultraviolet light with a wavelength of 200nm to 270nm or femtosecond laser with a wavelength of 400nm to 540nm to efficiently write optical information in the electron-trapping rare earth co-doped yttrium germanate optical storage medium;

thermally exciting at the temperature higher than 100 ℃ or optically exciting with laser with the wavelength of 400 nm-1250 nm to realize one-time or multiple-time reading of optical information in the electron capture type rare earth co-doped yttrium germanate optical storage medium.

4. A method for preparing an electron-trapping rare earth co-doped yttrium germanate optical storage medium according to any one of claims 1 to 3, comprising:

5. The preparation method according to claim 4, wherein the pre-sintering treatment is carried out at a temperature of 600 to 1000 ℃ for 1.5 to 5 hours; the sintering synthesis temperature is 1100-1700 ℃, and the time is 3-10 hours;

preferably, the pre-sintered powder is pressed and molded and then sintered; more preferably, the calcined powder and the binder are mixed and then press-molded and sintered.

6. An electron capture type rare earth co-doped yttrium germanate ceramic optical storage medium is characterized in that electron capture type rare earth co-doped yttrium germanate optical storage medium pre-sintered powder and a binder are mixed, dried, pressed and molded, and then calcined at 600-1000 ℃ for 1.5-4 hours to obtain the electron capture type rare earth co-doped yttrium germanate optical storage medium ceramic wafer.

7. An electron-trapping rare-earth co-doped yttrium germanate optical storage medium film, which is characterized by comprising: transparent high molecular material is used as a substrate, and electron capture type rare earth co-doped yttrium germanate optical storage medium powder is distributed in the substrate; the content of the electron capture type rare earth co-doped yttrium germanate optical storage medium powder is 10-50 wt%.

8. The electron-trapping type rare earth co-doped yttrium germanate optical storage medium film according to claim 7, wherein the particle size of the electron-trapping type rare earth co-doped yttrium germanate optical storage medium powder is 50 nm-2 μm; the thickness of the electron capture type rare earth co-doped yttrium germanate optical storage medium film is at least 500 nm.

9. The electron-trapping type rare earth co-doped yttrium germanate optical storage medium film according to claim 7 or 8, wherein the light excitation is performed under ultraviolet light with a wavelength of 200nm to 270nm or femtosecond laser with a wavelength of 400nm to 540nm, and the uniform movement of the movable film-carrying sample stage in an x-y plane is matched to realize the writing and reading of optical information on the electron-trapping type rare earth co-doped yttrium germanate optical storage medium film.

10. An application of an electron capture type rare earth co-doped yttrium germanate ceramic optical storage medium or an electron capture type rare earth co-doped yttrium germanate optical storage medium film in binary optical information storage is characterized by comprising the following steps:

(2) the laser with the wavelength of 400 nm-1250 nm is adopted to carry out linear continuous scanning on the electron capture type rare earth co-doped yttrium germanate ceramic optical storage medium or the electron capture type rare earth co-doped yttrium germanate optical storage medium film written with optical information, and two differential states of 'non-luminescence' and 'luminescence' are recorded in the scanning direction to represent two states of '0' and '1' in binary information;

wherein the diameter of the ultraviolet light beam or the focused femtosecond laser beam is 10 nm-2 μm.