CN109371502B - A preparation method and application of cubic pyrochlore phase nanofibers based on electrospinning method - Google Patents

Abstract

The invention discloses a preparation method and application of a cubic pyrochlore phase nanofiber based on an electrostatic spinning method. Dimethylformamide is used as a solvent, and an appropriate amount of polyvinylpyrrolidone is added to form a Taylor cone under an electrostatic field. One-dimensional nanomaterials are prepared by electrospinning under the force of liquid surface tension and electric field, and then the one-dimensional nanomaterials of cubic pyrochlore phase are prepared by removing organic residues through the processes of heating, heat preservation, and cooling. The doping process of other rare earth ions and the traditional double-doping or multi-doping process are avoided, the preparation method is simple and easy to operate, has good repeatability, and can meet the requirements of mass production. The green up-conversion light-emitting substrate involved is an oxide, which has good chemical stability, non-toxicity and low price, and can easily meet the needs of industrial production. The prepared one-dimensional pure pyrochlore phase nanomaterials are expected to play an important role in display, anti-counterfeiting, biological detection, infrared sensors, solar photovoltaic devices and other fields.

Description

A method for preparing cubic pyrochlore phase nanofibers based on electrospinning method and the same application

technical field

The invention belongs to the technical field of preparation and luminescence of rare earth ternary Bi ₂ Ti ₂ O ₇ : Er compound one-dimensional nanomaterials, and particularly relates to a preparation method of cubic pyrochlore phase nanofibers based on an electrospinning method and application thereof.

Background technique

Upconversion luminescent material is a new type of optical functional material that can convert infrared light invisible to the naked eye into visible light, also known as multiphoton material. It has very important application value in the fields of anti-counterfeiting, display, biological detection, imaging, and photothermal treatment of diseases. At present, the main up-conversion light-emitting materials can be divided into rare earth fluorides (represented by NaYF ₄ etc.), rare earth oxyhalides (represented by YOCl ₃ etc.), rare earth oxysulfides (represented by La ₂ O ₂ S, Y, etc.) ₂ O ₂ S, etc.), rare earth oxides, and composite oxides (represented by Y ₂ O ₃ , etc.). Among them, rare earth-doped fluoride upconversion luminescent materials have been widely studied due to their low phonon energy and small non-radiative relaxation. Among them, the hexagonal NaYF ₄ matrix material has become the most studied compound among rare earth fluorides due to its high luminous efficiency. Light, green light, blue light and other visible light excitation.

The Bi ₂ Ti ₂ O ₇ : Er ternary compound has a cubic pyrochlore structure, belongs to the Fd-3m(227) space point group, and has a lattice constant of a=10.359 angstroms. So far, the reports on the Bi ₂ Ti ₂ O ₇ matrix mainly include the following aspects: From the application point of view, the Bi ₂ Ti ₂ O ₇ material can be used as a photocatalyst; it also has a high dielectric constant, It is also suitable for use as a storage medium in dynamic random access memory (DRAM); there are relatively few reports on its optical properties. But so far there is no report on the upconversion performance of Bi ₂ Ti ₂ O ₇ by single rare earth doping. Oxides have the advantages of good chemical stability, high mechanical strength, and non-toxicity. Therefore, oxides have a wider range of applications than fluoride systems. Therefore, it is very necessary to study upconversion materials based on oxides. At the same time, because the one-dimensional nanomaterial structure has a large specific surface area and a special one-dimensional structure, it satisfies the transmission of photons along one-dimensional direction, avoids the scattering of photons on the chaotic interface, and is beneficial to obtain better luminescence performance.

In terms of preparation process, Bi ₂ Ti ₂ O ₇ materials mainly focus on sol-gel method, hydrothermal method, solid-phase reaction method, various deposition methods (such as laser pulse deposition method, etc.); through electrospinning method Obtaining one-dimensional Bi ₂ Ti ₂ O ₇ nanofibers is a big challenge.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a method for preparing pyrochlore phase Bi ₂ Ti ₂ O ₇ :Er nanofibers based on the electrospinning method and up-conversion luminescence in view of the deficiencies in the above-mentioned prior art. The method obtains a one-dimensional nanomaterial precursor. The pure cubic pyrochlore phase Bi ₂ Ti ₂ O ₇ :Er ternary compound was obtained by subsequent heat treatment, which was obtained for the first time without other rare earth elements as sensitizer doping and with oxide as matrix. The up-converted green glow.

The present invention adopts the following technical solutions:

A method for preparing cubic pyrochlore phase nanofibers based on an electrospinning method, characterized in that, using dimethylformamide as a solvent, adding polyvinylpyrrolidone to prepare an electrospinning precursor solution, and droplets forming Taylor cones under an electrostatic field , one-dimensional nanomaterials are prepared by electrospinning method, and then the residual organic matter is removed by heating, heat preservation and cooling to prepare cubic pyrochlore phase Bi ₂ Ti ₂ O ₇ : Er nanomaterials.

Specifically, the steps for preparing the electrospinning precursor solution are as follows:

S1, acetic acid and dimethylformamide are mixed and stirred to make solution A;

S2, stirring the solution A prepared in step S1 and adding tetrabutyl titanate to make solution B;

S3, the solution B prepared in step S2 is stirred and erbium nitrate is added to make solution C;

S4, in the solution C prepared in step S3, add bismuth nitrate to make solution D;

S5, adding polyvinylpyrrolidone to the solution D prepared in step S4 and stirring to prepare an electrospinning precursor solution.

Further, in step S1, the mass ratio of acetic acid to dimethylformamide is (0.3-0.6):1.

Further, in step S2, the mass ratio of solution A to tetrabutyl titanate is (1.5-2):1.

Further, in step S3, the mass ratio of solution B to er nitrate is (14-32):1.

Further, in step S4, the mass ratio of solution C to bismuth nitrate is (15-34):1.

Further, in step S5, polyvinylpyrrolidone with a mass fraction of 5-20% is added.

Specifically, a high voltage of 18-25 kV is applied, the rate of the micro-flow feeder is controlled to be 10-20 μl/m, and the electrospinning precursor liquid is sprayed onto the collector.

Specifically, the removal of organic residues is as follows: the heating rate is 4-10°C/min, the annealing temperature is 600-800°C, the treatment time is 1-3 hours, and then naturally cooled to room temperature.

Application of pyrochlore phase Bi ₂ Ti ₂ O ₇ :Er nanomaterials prepared by the preparation method of cubic pyrochlore phase nanofibers based on electrospinning method in up-conversion green light-emitting nanomaterials, and the up-conversion green light-emitting nanomaterials are suitable for display devices, Anti-counterfeiting devices, biodetection devices, infrared sensors and solar photovoltaic devices.

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

The present invention is a method for preparing pyrochlore phase Bi ₂ Ti ₂ O ₇ : Er nano-materials by electrospinning, using dimethylformamide DMF as a solvent, adding an appropriate amount of polyvinylpyrrolidone PVP, and forming a Taylor droplet in an electrostatic field Cone, one-dimensional nanomaterials were prepared by electrospinning under the force of liquid surface tension and electric field, and then after heating, heat preservation, and cooling, the organic substances were removed to prepare pure cubic pyrochlore phase Bi ₂ Ti ₂ O ₇ : Er one-dimensional nanomaterials, which realize visible light emission under near-infrared excitation, are a new type of single-doped upconversion luminescent nanofibers.

Further, in order to meet the requirements of industrial production, acetic acid and DMF are used as solvents, acetic acid can inhibit the hydrolysis of the titanium source, and DMF can be used as a solvent to fully mix the solutes, achieve the purpose of accurately controlling the stoichiometric ratio, and obtain solution A; A certain amount of tetrabutyl titanate is added to solution A and fully dissolved, the purpose is to introduce titanium source to obtain solution B; a quantitative amount of erbium nitrate is added to solution B and fully stirred for the purpose of introducing erbium source, so that It is mixed with tetrabutyl titanate at the atomic level, and solution C is obtained; a quantitative amount of bismuth nitrate is added to solution C and fully stirred, the purpose is to introduce a bismuth source and obtain solution D; an appropriate amount of PVP is added to increase the solution. , which establishes the basis for electrospinning.

Further, a high voltage power supply is applied with the aim of forming a Taylor cone at the needle.

Further, the nanowires on the collector are annealed, in order to obtain high crystallinity pyrochlore phase Bi ₂ Ti ₂ O ₇ :Er nanomaterials.

The invention also discloses an up-conversion green light-emitting nanomaterial, which can be obtained without any sensitizer, and is expected to play an important role in the fields of display, anti-counterfeiting, biological detection, immune analysis, solar photovoltaic device preparation and the like.

To sum up, the preparation method of the present invention is simple and easy to operate, has good repeatability, can meet the requirements of mass production, avoids doping processes of other rare earth ions, and simplifies the traditional double-doping or multi-doping process.

The technical solutions of the present invention will be further described in detail below through the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is the scanning electron microscope image (SEM) of Bi ₂ Ti ₂ O ₇ : Er nanomaterial synthesized in Example 1 of the present invention;

FIG. 2 is a graph showing the up-conversion luminescence properties of the Bi ₂ Ti ₂ O ₇ : Er nanomaterial synthesized in Example 2 of the present invention;

3 is the X-ray diffraction spectrum of the Bi ₂ Ti ₂ O ₇ : Er nanomaterial synthesized in Example 3 of the present invention;

4 is the X-ray diffraction spectrum of the Bi ₂ Ti ₂ O ₇ : Er nanomaterial synthesized in Example 4 of the present invention;

5 is the X-ray diffraction spectrum of the Bi ₂ Ti ₂ O ₇ : Er nanomaterial synthesized in Example 5 of the present invention.

Detailed ways

The invention provides a method for preparing cubic pyrochlore phase nanofibers based on an electrospinning method and an application thereof. DMF is used as a solvent and an appropriate amount of PVP is added to form a Taylor cone by droplets under an electrostatic field. One-dimensional nanomaterials are obtained under the force of the surface tension of the liquid and the electric field, and then through three stages of heating, heat preservation, and cooling, a pure cubic pyrochlore phase Bi ₂ Ti ₂ O ₇ : Er one-dimensional with good crystalline properties is obtained nanomaterials. By excitation with a near-infrared light source (such as 980 nm), green emission with up-conversion observable to the naked eye was obtained for the first time without other rare earth element doping and oxide-based matrix.

The present invention is a method for preparing cubic pyrochlore phase nanofibers based on an electrospinning method, comprising the following steps:

S1, DMF and acetic acid are mixed and stirred according to the mass ratio of 1:(0.3～0.6), namely obtain solution A;

S2. In the process of constant stirring, add tetrabutyl titanate with a mass ratio of 1:(1.5-2) to solution A into solution A, and then solution B can be obtained;

S3, adding the erbium nitrate whose mass ratio to solution B is 1: (14～32) into solution B during constant stirring to obtain solution C;

S4, adding the bismuth nitrate whose mass ratio to solution C is 1:(15～34) into solution C during constant stirring to obtain solution D;

S5, adding 5-10% (mass fraction) of PVP to solution C and stirring to prepare an electrospinning precursor solution;

S6. Under the condition of applying 18-25 kV high-voltage power supply, the precursor liquid is sprayed onto the collector at a controlled rate of 10-20 μl/m through the micro-flow feeder for electrospinning;

S7. After the electrospinning is completed, the nanomaterials on the collector are annealed to obtain pyrochlore phase Bi ₂ Ti ₂ O ₇ :Er nanomaterials with high crystallinity.

The heating rate is 2-10° C./min, the temperature of the annealing treatment is 600-800° C., the treatment time is 1-3 hours, and then it is naturally cooled to room temperature.

Through the illumination of a near-infrared light source (980 nanometers), green luminescence visible to the naked eye in the visible wavelength range is excited, and an up-conversion green luminescent nanomaterial without other rare earth element doping and based on oxide is obtained.

The invention combines the electrospinning method to obtain one-dimensional Bi ₂ Ti ₂ O ₇ : Er nano-material, and realizes the up-conversion process that can be realized by single-doping erbium, which has particularly important significance and practical value

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. The components of the embodiments of the invention generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations. Thus, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

DMF and acetic acid were mixed in a mass ratio of 0.3:1, and a transparent solution was formed by magnetic stirring; then 0.8 ml of tetrabutyl titanate was added and fully dissolved by stirring; 0.11 g of erbium nitrate was added under rapid stirring; After it was fully dissolved, 1.05 g of bismuth nitrate was added and fully stirred to dissolve it. Finally, PVP with a mass fraction of 5% was added, and the electrospinning precursor solution was obtained after magnetic stirring. Under the control voltage of 18KV and the flow rate of 10μl/m, a large amount of nanomaterials appeared on the collector. After the electrospinning was completed, the nanomaterials on the collector were transferred to a muffle furnace and heated at 4°C/min. The rate of increase to 600 ℃ for 1 hour, the pyrochlore phase Bi ₂ Ti ₂ O ₇ : Er nanomaterial with high crystallinity can be obtained.

Fig. 1 shows the scanning electron micrograph (SEM) of the obtained Er ₂ Ti ₂ O ₇ nanomaterials, and it can be seen from the figure that the diameters of the nanomaterials are distributed in the range of 200 to 500 nanometers.

Example 2

DMF and acetic acid were mixed in a mass ratio of 0.4:1, and a transparent solution was formed by magnetic stirring; then 0.81 ml of tetrabutyl titanate was added and fully dissolved by stirring; 0.13 g of erbium nitrate was added under rapid stirring; After it was fully dissolved, 1.02 g of bismuth nitrate was added and fully stirred to dissolve it. Finally, PVP with a mass fraction of 6% was added, and the electrospinning precursor solution was obtained after magnetic stirring. Under the control voltage of 20KV and the flow rate of 12μl/m, a large amount of nanomaterials appeared on the collector. After the electrospinning was completed, the nanomaterials on the collector were transferred to a muffle furnace and heated at 6°C/min. The rate of increase to 650 ℃ for 1.5 hours, the pyrochlore phase Bi ₂ Ti ₂ O ₇ : Er nanomaterial with high crystallinity can be obtained.

Figure 2 shows the up-conversion luminescence properties obtained by using a laser with a wavelength of 980 nm as the excitation source. The test wavelength range is 200-900 nm, and the integration time is 30 ms.

Example 3

DMF and acetic acid were mixed in a mass ratio of 0.4:1, and a transparent solution was formed by magnetic stirring; then 0.83 ml of tetrabutyl titanate was added and fully dissolved by stirring; 0.13 g of erbium nitrate was added under rapid stirring; After it was fully dissolved, 1.02 g of bismuth nitrate was added and fully stirred to dissolve it. Finally, PVP with a mass fraction of 8% was added, and the electrospinning precursor solution was obtained after magnetic stirring. Under the control voltage of 22KV and the flow rate of 15μl/m, a large amount of nanomaterials appeared on the collector. After the electrospinning was completed, the nanomaterials on the collector were transferred to a muffle furnace and heated at 8°C/min. The rate of increase to 750 ℃ for 2 hours, the pyrochlore phase Bi ₂ Ti ₂ O ₇ : Er nanomaterials with high crystallinity can be obtained.

Figure 3 shows the X-ray diffraction pattern of the obtained nanomaterials. The obtained powders were scanned between 10 and 80 degrees using an X-ray diffractometer. The powder samples showed polycrystalline diffraction characteristics, all diffraction peaks and Er ₂ Ti ₂ O ₇ standard card (PDF#97-009-9436) is in complete agreement, and no impurity peaks appear, which proves that the obtained powder is Bi ₂ Ti ₂ O ₇ pyrochlore phase. The 2θ angle is the strongest peak at 29.854°, which corresponds to the (222) crystal plane of the Bi ₂ Ti ₂ O ₇ standard card.

Example 4

DMF and acetic acid were mixed in a mass ratio of 0.5:1, and a transparent solution was formed by magnetic stirring; then 0.84 ml of tetrabutyl titanate was added and fully dissolved by stirring; 0.18 g of erbium nitrate was added under rapid stirring; After it was fully dissolved, 0.97 g of bismuth nitrate was added and fully stirred to dissolve it. Finally, PVP with a mass fraction of 9% was added, and the electrospinning precursor solution was obtained after magnetic stirring. Under the control voltage of 24KV and the flow rate of 18μl/m, a large amount of nanomaterials appeared on the collector. After the electrospinning was completed, the nanomaterials on the collector were transferred to a muffle furnace and heated at 8°C/min. The rate of increase to 800 ℃ for 2 hours, the pyrochlore phase Bi ₂ Ti ₂ O ₇ : Er nanomaterial with high crystallinity can be obtained.

Figure 4 shows the X-ray diffraction pattern of the obtained nanomaterials: all the diffraction peaks are in perfect agreement with the Bi ₂ Ti ₂ O ₇ standard card (PDF#97-009-9436), which proves that the Bi ₂ Ti has not changed under this process. _The structure of the _2O7 cubic pyrochlore phase.

Example 5

DMF and acetic acid were mixed in a mass ratio of 0.6:1, and a transparent solution was formed by magnetic stirring; then 0.85 ml of tetrabutyl titanate was added and fully dissolved by stirring; 0.15 g of erbium nitrate was added under rapid stirring; After it was fully dissolved, 0.99 g of bismuth nitrate was added and fully stirred to dissolve it. Finally, PVP with a mass fraction of 10% was added, and the electrospinning precursor solution was obtained after magnetic stirring. Under the control voltage of 25KV and the flow rate of 20μl/m, a large amount of nanomaterials appeared on the collector. After the electrospinning was completed, the nanomaterials on the collector were transferred to a muffle furnace and heated at 10°C/min. The rate of increase to 800 ℃ for 3 hours, the pyrochlore phase Bi ₂ Ti ₂ O ₇ : Er nanomaterial with high crystallinity can be obtained.

Figure 5 shows the X-ray diffraction pattern of the obtained nanomaterials: all the diffraction peaks are completely consistent with the Bi ₂ Ti ₂ O ₇ standard card (PDF#97-009-9436), and no impurity peaks appear, which proves that under this process The structure of the Bi ₂ Ti ₂ O ₇ cubic pyrochlore phase was also not changed.

Since the invention does not involve the use of sensitizers, the doping process of other rare earth ions is avoided, the traditional double-doping or multi-doping process is simplified, and the one-dimensional nanomaterial preparation method adopted is simple and easy to implement and has good repeatability. , which can meet the requirements of mass production. The green up-conversion luminescence involved can be obtained without any sensitizer, and the adopted matrix is an oxide, which has good chemical stability. It is non-toxic and inexpensive and can easily meet the needs of industrial production.

The one-dimensional pure pyrochlore phase Bi ₂ Ti ₂ O ₇ : Er nanomaterial prepared by the preparation method of the invention is expected to play an important role in the fields of display, anti-counterfeiting, biological detection, infrared sensors, solar photovoltaic devices and the like.

The above content is only to illustrate the technical idea of the present invention, and cannot limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention all fall within the scope of the claims of the present invention. within the scope of protection.

Claims (4)

1. a method for preparing cubic pyrochlore phase nanofibers based on electrospinning, is characterized in that, with dimethylformamide as solvent, adding polyvinylpyrrolidone to make electrospinning precursor liquid, droplet formation under electrostatic field Taylor cone, one-dimensional nanomaterials are prepared by electrospinning method, and then the residual organic matter is removed by heating, heat preservation and cooling, and the cubic pyrochlore phase Bi ₂ Ti ₂ O ₇ : Er nanomaterials are prepared; The steps for preparing the electrospinning precursor solution are as follows: S1. Mix and stir acetic acid and dimethylformamide with a mass ratio of (0.3~0.6):1 to prepare solution A; S2. Stir the solution A prepared in step S1 and add tetrabutyl titanate to prepare solution B. The mass ratio of solution A to tetrabutyl titanate is (1.5~2):1; S3, stirring the solution B prepared in step S2 and adding erbium nitrate to prepare solution C, the mass ratio of solution B and er nitrate is (14~32): 1; S4, adding bismuth nitrate to solution C prepared in step S3 to prepare solution D, and the mass ratio of solution C to bismuth nitrate is (15~34): 1; S5, adding polyvinylpyrrolidone with a mass fraction of 5-20% to the solution D prepared in step S4 and stirring to prepare an electrospinning precursor solution. 2. the method for preparing cubic pyrochlore phase nanofibers based on electrospinning method according to claim 1, is characterized in that, applying 18～25 kV high-voltage electricity, the speed of control micro-flow precessor is 10～20µl/ m, the electrospinning precursor is sprayed onto the collector. 3. The method for preparing cubic pyrochlore phase nanofibers based on electrospinning method according to claim 1, wherein the removal of organic residues is specifically: the heating rate is 4～10 ℃/min, and the annealing temperature is 600～800 ℃ ℃, the treatment time is 1 to 3 hours, and then naturally cooled to room temperature. 4. The application of pyrochlore phase Bi ₂ Ti ₂ O ₇ :Er nanomaterials prepared by the method for preparing cubic pyrochlore phase nanofibers based on electrospinning according to claim 1 in up-conversion green luminescent nanomaterials, the up-conversion green Luminescent nanomaterials are suitable for display devices, anti-counterfeiting devices, biodetection devices, infrared sensors and solar photovoltaic devices.

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