阅读说明：本技术 一种稀土掺杂bczt压电纳米纤维及其制备方法和应用 (Rare earth doped BCZT piezoelectric nanofiber and preparation method and application thereof ) 是由 李向东 王祥达 何建方 张军 任奕菲 腾世国 李建霖 于 2021-07-02 设计创作，主要内容包括：本发明提供了一种稀土掺杂BCZT纳米纤维及其制备方法和应用。本发明提供的稀土掺杂BCZT纳米纤维,化学式为Ba-(0.85-x)M-(x)Ca-(0.15)(Zr-(0.1)Ti-(0.9))O-(3),其中M为稀土元素,0.01≤x≤0.05；该稀土掺杂BCZT纳米纤维长为5～10μm,径向宽度为50～200nm。采用溶胶凝胶法结合静电纺丝制备,实现了掺杂元素在原子级别的分散及均匀掺杂,稀土掺杂BCZT纳米纤维的晶体连续性好,有效提升了BCZT陶瓷的压电性能、介电性能、降低介电损耗。该稀土掺杂BCZT纳米纤维可直接与柔性高分子材料复合制备压电纳米发电机,有效应用于生物医学、无线传感、柔性器件等纳米电子器件领域。(The invention provides a rare earth doped BCZT nanofiber and a preparation method and application thereof. The rare earth doped BCZT nanofiber provided by the invention has a chemical formula of Ba 0.85‑x M x Ca 0.15 (Zr 0.1 Ti 0.9 )O 3 Wherein M is a rare earth element, x is more than or equal to 0.01 and less than or equal to 0.05; the rare earth doped BCZT nanofiber has the length of5 to 10 μm and a radial width of 50 to 200 nm. The preparation method combines a sol-gel method with electrostatic spinning, realizes the dispersion and uniform doping of doping elements at an atomic level, has good crystal continuity of the rare earth doped BCZT nanofiber, effectively improves the piezoelectric property and the dielectric property of the BCZT ceramic, and reduces the dielectric loss. The rare earth doped BCZT nanofiber can be directly compounded with a flexible high polymer material to prepare a piezoelectric nano generator, and is effectively applied to the fields of nano electronic devices such as biomedicine, wireless sensors, flexible devices and the like.)

1. The rare earth doped BCZT nanofiber is characterized in that the rare earth doped BCZT nanofiber has a chemical formula of Ba_{0.85- x}M_xCa_0.15(Zr_0.1Ti_0.9)O₃Wherein M is a rare earth element, x is more than or equal to 0.01 and less than or equal to 0.05; the rare earth doped BCZT nanofiber has a length of 5-10 mu m and a radial width of 50-200 nm.

2. The rare earth-doped BCZT nanofiber according to claim 1, wherein M is one or more of La, Sm, Eu, Dy or Y in said formula.

3. The preparation method of the rare earth doped BCZT nanofiber as claimed in any one of claims 1 to 2, which is characterized by comprising the following steps:

s1: dissolving barium salt, calcium salt and rare earth salt in a solvent to obtain a solution A; dissolving tetrabutyl titanate and zirconium salt in a solvent to obtain a solution B; mixing the solution A and the solution B, adding acetylacetone to obtain a mixed solution, and mixing and stirring to obtain rare earth doped BCZT sol;

s2: and adding an organic additive into the obtained rare earth doped BCZT sol, mixing and stirring until the sol is clear and transparent, spinning the sol by adopting an electrostatic spinning method to obtain a nanofiber precursor, and calcining to obtain the rare earth doped BCZT nanofiber.

4. The method according to claim 3, wherein the barium salt in S1 is barium acetate; the calcium salt is one of calcium acetate or calcium nitrate; the rare earth salt is one or more of lanthanum nitrate, samarium nitrate, europium nitrate, dysprosium nitrate and yttrium nitrate; the zirconium salt is one of zirconyl nitrate or zirconium oxychloride.

5. The preparation method according to claim 3, wherein the solvent in the solution A in S1 is a mixed solvent of glacial acetic acid and water, wherein the volume ratio of glacial acetic acid to water is 1: 1-2; the solvent in the solution B is a mixed solvent of glacial acetic acid and absolute ethyl alcohol, wherein the volume ratio of the glacial acetic acid to the water is 1: 1-2.

6. The preparation method according to claim 3, wherein the molar ratio of the tetrabutyl titanate to the acetylacetone in S1 is 1: 2-3; in the mixing and stirring process, the pH of the mixed solution is adjusted to 3.5-4, and the mixed solution is stirred in a water bath at 50-90 ℃ for 2-8 hours.

7. The preparation method of claim 3, wherein the organic additive in S2 is one or more selected from polyvinylpyrrolidone, polyethylene glycol, and polycaprolactone; the mass of the organic additive is 8-14% of the rare earth doped BCZT sol; the mixing and stirring process is water bath stirring at 40-80 ℃ for 2-8 h.

8. The method according to claim 3, wherein the parameters of the electrospinning method in S2 are: the positive electrode voltage is 5-15 kV, the negative electrode voltage is-5 to-15 kV, the distance from the positive electrode needle head to the negative electrode collecting plate is 5-30 cm, and the sample feeding speed is 2-5 mL/h.

9. The preparation method according to claim 3, wherein the calcination temperature is 700 to 850 ℃ and the calcination time is 2 to 4 hours.

10. The use of the rare earth doped BCZT nanofiber as claimed in any one of claims 1 to 2 in the field of nanoelectronic devices.

Technical Field

The invention belongs to the technical field of functional materials and electronic devices, and particularly relates to a rare earth doped BCZT piezoelectric nanofiber and a preparation method and application thereof.

Background

Barium Calcium Zirconate Titanate (BCZT) is attracting attention in many lead-free piezoelectric material systems because it has piezoelectric properties equivalent to PZT (d33 ═ 500-. In the literature (Maraj M, Wei W, Peng B, et al materials.2019,12(21):3641), scientists generally adopt a solid phase reaction method to prepare rare earth element (La, Sm, Eu, Dy and Y) doped BCZT powder, and replace part of Ba by rare earth element ions with smaller ion radius²⁺The ions shrink the unit cell volume, increase the interface and electric domain density, enhance the interface polarization, improve the ferroelectric relaxation degree, improve the piezoelectric property and the dielectric property, reduce the dielectric loss and improve the comprehensive performance of BCZT. For example, Chinese patent No. CN102515754B introduces lanthanum oxide doped modified barium calcium zirconate titanate ceramic and a preparation method thereof, and La is doped into BCZT by a solid phase method to prepare modified La-BCZT ceramic. But the solid-phase reaction method has the phenomenon of uneven element doping; the synthesis temperature is generally 1200-1350 ℃, the temperature is high, and the energy consumption is high; secondary ball milling is needed, and the process consumes long time; preparation of BThe CZT powder is in a micron-scale irregular particle shape, the crystal is discontinuous, the defect exists, and the CZT powder needs to be applied to the piezoelectric ceramic block through high-temperature sintering at 1400-1500 ℃. These problems limit the application of BCZT in the field of nano-electronics such as biomedicine, wireless sensing, flexible devices, etc.

The BCZT prepared by the sol-gel method has lower synthesis temperature than that of the solid-phase reaction method, and the prepared BCZT has high uniformity, accurate components and high purity. The BCT-BZT-La-xIr is prepared by a modified Pechini method in research (preparation of barium zirconate titanate calcium-based lead-free piezoelectric ceramic, research of structure and electrical properties, Phillips Yongshang, Philippines university of China, 2016)⁴⁺The piezoelectric properties of the ceramic and the BCT-BZT-La-xEr ceramic are not obviously improved, such as the d of the ceramic and the BCT-BZT-La-xEr ceramic₃₃The test values were only 269pC/N and 196 pC/N.

Disclosure of Invention

Aiming at the problem that the piezoelectric performance of rare earth doped BCZT nano piezoelectric ceramic prepared by the prior art is poor, the invention aims to provide rare earth doped BCZT piezoelectric nano fiber. The rare earth doped BCZT piezoelectric nanofiber has good crystal continuity, excellent piezoelectric property and dielectric property and low dielectric loss; the piezoelectric nano generator can be compounded with a flexible high polymer material to prepare the piezoelectric nano generator, and is effectively applied to the fields of nano electronic devices such as biomedicine, wireless sensing, flexible devices and the like.

The invention also aims to provide a preparation method of the rare earth doped BCZT piezoelectric nanofiber.

The invention also aims to provide application of the rare earth doped BCZT piezoelectric nanofiber in the field of nano electronic devices.

In order to achieve the above object, the present invention provides the following technical solutions:

a rare earth doped BCZT nanofiber has a chemical formula of Ba_0.85-xM_xCa_0.15(Zr_0.1Ti_0.9)O₃Wherein M is a rare earth element, x is more than or equal to 0.01 and less than or equal to 0.05; the rare earth doped BCZT nanofiber has a length of 5-10 mu m and a radial width of 50-200 nm.

Because the piezoelectric performance of lead-free piezoelectric material barium zirconate titanate (BCZT) is poorer than that of PZT piezoelectric ceramic, part of Ba is replaced by rare earth element ions with smaller ionic radius²⁺The ions shrink the unit cell volume, increase the interface and electric domain density, enhance the interface polarization, improve the ferroelectric relaxation degree, improve the piezoelectric property and the dielectric property, reduce the dielectric loss, thereby effectively improving the comprehensive performance of the BCZT.

At present, a great deal of research is carried out on preparing a rare earth doped BCZT material by doping by a solid-phase reaction method, but the solid-phase reaction method belongs to a mechanical mixing process and has the phenomenon of uneven element doping; the synthesis temperature is generally 1200-1350 ℃, the temperature is high, the energy consumption is large, secondary ball milling processing is needed, and the process is long in time consumption; the prepared powder is in a micron-level irregular particle shape, ceramic crystals are discontinuous, defects exist, piezoelectric performance and dielectric performance are affected, and dielectric loss is large; the piezoelectric ceramic block needs to be prepared by high-temperature calcination at 1400-1500 ℃, and cannot be directly used in the fields of nano electronic devices which cannot be processed at high temperature, such as biomedicine, wireless sensing, flexible devices and the like.

According to the rare earth doped BCZT nanofiber provided by the invention, the doping elements are dispersed and uniformly doped at an atomic level, the size of the fiber is small, the continuity of crystals is good, the piezoelectric property and the dielectric property of BCZT ceramic can be effectively improved, and the dielectric loss is reduced; the piezoelectric constant can reach 432(pC/N), the dielectric constant is 3267, and the dielectric loss is 0.015.

Preferably, M in the chemical formula is one or more of La, Sm, Eu, Dy or Y.

The invention also provides a preparation method of the rare earth doped BCZT nanofiber, which comprises the following steps:

s1: dissolving barium salt, calcium salt and rare earth salt in a solvent to obtain a solution A; dissolving tetrabutyl titanate and zirconium salt in a solvent to obtain a solution B; mixing the solution A and the solution B, adding acetylacetone to obtain a mixed solution, and mixing and stirring to obtain rare earth doped BCZT sol;

s2: and adding an organic additive into the obtained rare earth doped BCZT sol, mixing and stirring until the sol is clear and transparent, spinning the sol by adopting an electrostatic spinning method to obtain a nanofiber precursor, and calcining to obtain the rare earth doped BCZT nanofiber.

The piezoelectric ceramic prepared by the electrostatic spinning method can ensure that the surface of the prepared nano-fiber is smooth, the solid is uniformly dispersed by operating and arranging, and the continuity of crystals is good; the nano-fiber has the advantages of small pores, high porosity and large specific surface area.

Preferably, the barium salt in S1 is barium acetate.

Preferably, the calcium salt in S1 is one of calcium acetate or calcium nitrate.

Preferably, the rare earth salt in S1 is one or more of lanthanum nitrate, samarium nitrate, europium nitrate, dysprosium nitrate or yttrium nitrate.

Preferably, the zirconium salt in S1 is one of zirconyl nitrate or zirconium oxychloride.

Preferably, the solvent in the solution A in S1 is a mixed solvent of glacial acetic acid and water, wherein the volume ratio of the glacial acetic acid to the water is 1: 1-2.

Preferably, the solvent in the solution B in the S1 is a mixed solvent of glacial acetic acid and absolute ethyl alcohol, wherein the volume ratio of the glacial acetic acid to the water is 1: 1-2.

Preferably, the molar ratio of tetrabutyl titanate to acetylacetone in S1 is 1: 2-3.

Preferably, in the mixing and stirring process in S1, the pH of the mixed solution is adjusted to 3.5-4, and the mixed solution is stirred in a water bath at 50-90 ℃ for 2-8 hours.

Preferably, the organic additive in S2 is one or more selected from polyvinylpyrrolidone (PVP), polyethylene glycol and polycaprolactone.

Preferably, the mass of the organic additive in S2 is 8% -14% of that of the rare earth doped BCZT sol.

Preferably, the mixing and stirring process in S2 is water bath stirring at 40-80 ℃ for 2-8 h.

Preferably, the parameters of the electrospinning method in S2 are: the positive electrode voltage is 5-15 kV, the negative electrode voltage is-5 to-15 kV, the distance from the positive electrode needle head to the negative electrode collecting plate is 5-30 cm, and the sample feeding speed is 2-5 mL/h.

Preferably, the calcining temperature is 700-850 ℃, and the calcining time is 2-4 h.

The application of the rare earth doped BCZT nanofiber in the field of nano electronic devices is also in the protection scope of the invention.

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

(1) the rare earth doped BCZT nanofiber provided by the invention has good crystal continuity; by rare earth doping, the piezoelectric property and the dielectric property of the BCZT ceramic can be effectively improved, and the dielectric loss is reduced; the rare earth doped BCZT nanofiber can be compounded with a flexible high polymer material to prepare a piezoelectric nano generator, and is effectively applied to the fields of biomedicine, wireless sensing, flexible devices and the like.

(2) The rare earth doped BCZT nanofiber is prepared by combining a sol-gel method and electrostatic spinning, and the preparation method is simple in process, low in cost, green, environment-friendly and strong in repeatability.

Drawings

FIG. 1 is an XRD pattern of samples prepared in examples 1 to 3 and comparative examples 1 to 2;

FIG. 2 is a scanning electron micrograph of the nanofiber prepared in example 1;

FIG. 3 is a scanning electron micrograph of the nanofiber prepared in example 2;

FIG. 4 is a scanning electron micrograph of the nanofiber prepared in example 3;

FIG. 5 is a scanning electron micrograph of nanofibers prepared in comparative example 1;

fig. 6 is a scanning electron microscope image of the nano powder prepared in comparative example 2.

Detailed Description

The invention is further illustrated by the following examples. These examples are intended to illustrate the invention and are not intended to limit the scope of the invention. Experimental procedures without specific conditions noted in the examples below, generally according to conditions conventional in the art or as suggested by the manufacturer; the raw materials, reagents and the like used are, unless otherwise specified, those commercially available from the conventional markets and the like.

Example 1

The embodiment provides a lanthanum-doped BCZT nanofiber, and the preparation method specifically comprises the following steps:

s1: according to the chemical formula Ba_0.85-xLa_xCa_0.15(Z_r0.1Ti_0.9)O₃Weighing raw materials of barium acetate, calcium acetate and lanthanum nitrate according to the stoichiometric ratio of the medium elements, dissolving the raw materials in a mixed solvent of glacial acetic acid and water, wherein the volume ratio of the glacial acetic acid to the water is 1:2, and x is 0.01 to obtain a solution A; weighing tetrabutyl titanate and zirconyl nitrate, dissolving in a mixed solvent of glacial acetic acid and absolute ethyl alcohol, wherein the volume ratio of the glacial acetic acid to the absolute ethyl alcohol is 1:2, and obtaining a solution B; and mixing the solution A and the solution B, adding acetylacetone serving as a complexing agent, wherein the molar ratio of tetrabutyl titanate to acetylacetone is 1:2, adding a proper amount of water to adjust the pH value to 4, and stirring in a water bath at 80 ℃ for 3 hours to obtain clear and transparent xLa-BCZT sol.

S2: adding PVP (polyvinyl pyrrolidone) into the sol obtained in the S1, wherein the mass of the PVP is 10% of the mass of the sol, stirring the mixture in a water bath kettle at 60 ℃ for 5 hours until the sol is clear and transparent, and spinning the sol by adopting an electrostatic spinning technology under the conditions that the positive voltage is 10kV, the negative voltage is-5 kV, the distance from a positive needle to a negative collecting plate is 15cm, and the sample feeding speed is 2mL/h to obtain an xLa-BCZT nanofiber precursor; and then calcining the mixture at 800 ℃ for 2h to obtain the xLa-BCZT nanofiber.

Example 2

In the sol-gel method for preparing xLa-BCZT sol in step S1 of example 2, x is 0.03, and the rest of the procedure is the same as in example 1.

Example 3

In the sol-gel method for preparing xLa-BCZT sol in step S1 of example 3, x is 0.05, and the rest of the procedure is the same as in example 1.

Example 4

The embodiment provides samarium-doped BCZT nanofiber, and the preparation method specifically comprises the following steps:

according to the chemical formula Ba_0.85-xSm_xCa_0.15(Z_r0.1Ti_0.9)O₃Weighing raw materials of barium acetate, calcium acetate and samarium nitrate according to the stoichiometric ratio of the medium elements, and the rest stepsSame as in example 1.

Example 5

The embodiment provides europium-doped BCZT nanofiber, and the preparation method specifically comprises the following steps:

according to the chemical formula Ba_0.85-xEu_xCa_0.15(Z_r0.1Ti_0.9)O₃The raw materials of barium acetate, calcium acetate and europium nitrate are weighed according to the stoichiometric ratio of the medium elements, and the rest steps are the same as those in the embodiment 1.

Comparative example 1

The comparative example provides a pure BCZT nanofiber, and the preparation method comprises the following steps:

the sol-gel method in step S1 of this comparative example was used to prepare xLa-BCZT sol, where x is 0, and the rest of the procedure was the same as in example 1.

Comparative example 2

The comparative example provides lanthanum-doped BCZT nano-powder, and the preparation method comprises the following steps:

firstly, xLa-BCZT sol was prepared according to the procedure of example 1, where x is 0.03; and then precipitating the sol at 80 ℃ for 12h to form gel, drying at 100 ℃ for 12h, keeping the temperature at 800 ℃ for 2h, calcining, and grinding for 10min to obtain the xLa-BCZT nano powder.

Performance testing

The X-ray diffraction phase analysis results of the samples prepared in examples 1 to 3 and comparative examples 1 to 2 of the present invention are shown in FIG. 1. As can be seen from fig. 1, all the samples prepared in examples and comparative examples have a single perovskite phase BCZT structure, and no other impurity phases exist.

Scanning electron micrographs of the xLa-BCZT nanofibers prepared in examples 1-3 of the invention are shown in FIGS. 2-4, and the prepared xLa-BCZT nanofibers have the advantages of about 5-10 μm in length, 50-200 nm in width and good crystal continuity.

The scanning electron microscope image of the BCZT nanofiber prepared in comparative example 1 of the invention is shown in FIG. 5, the prepared pure BCZT nanofiber has the length of about 2-10 μm and the radial width of 500-1000 nm; the radial dimension is significantly increased compared to the lanthanum doped nanofibers of example 1. It is known that La having a small ionic radius is doped with lanthanum²⁺Ionic substitutionPart of Ba²⁺Ions shrink the unit cell volume, and the size of the BCZT nanofiber can be obviously reduced.

The scanning electron microscope image of the lanthanum-doped BCZT nano-powder prepared in comparative example 2 of the invention is shown in FIG. 6, and the prepared nano-powder has the particle size of 20-200 nm, and the particles are non-uniform and partially agglomerated. The invention shows that the lanthanum-doped BCZT nano-powder structure can be adjusted to be a nano-fiber structure through an electrostatic spinning process, and the agglomeration phenomenon is effectively reduced.

In order to evaluate the performance of the samples prepared in examples 1-3 and comparative examples 1-2 of the invention, the samples were pressed into green wafers with a diameter of 15mm and a thickness of 1mm, and the green wafers were sintered at 1400 ℃ for 2 hours to prepare ceramic wafers, the surfaces of the ceramic wafers were polarized by silver electrodes for 30 minutes at 40 ℃ under an electric field of 4kV/mm, and the test electrical constants, dielectric constants and dielectric losses were measured after standing for 12 hours, and the results are shown in Table 1.

TABLE 1 piezoelectric Properties of samples in examples 1 to 3 and comparative examples 1 to 2

As can be seen from table 1, the BCZT ceramics prepared from the lanthanum-doped BCZT nanofibers in examples 1 to 3 have higher piezoelectric properties, dielectric properties, and lower dielectric loss than the BCZT ceramics prepared from the pure BCZT nanofibers in comparative example 1 and the lanthanum-doped BCZT nanopowder in comparative example 2. Where x is 0.03, the maximum piezoelectric constant, the highest dielectric constant and the lowest dielectric loss are achieved. La due to smaller ionic radius²⁺Ion-substituted moiety Ba²⁺The ions shrink the unit cell volume, increase the interface and electric domain density, enhance the interface polarization, improve the ferroelectric relaxation degree, improve the piezoelectric property and the dielectric property of the BCZT ceramic, reduce the dielectric loss and improve the comprehensive property of the BCZT ceramic.

The invention prepares the continuous xLa-BCZT nanofiber at a lower temperature process, has simple preparation process, low cost, environmental protection and strong repeatability, can be directly compounded with flexible high polymer materials to prepare the piezoelectric nano generator, and is applied to the fields of nano electronic devices such as biomedicine, wireless sensors, flexible devices and the like.

The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.