A lead zirconate titanate / lead titanate periodic laminated film, a preparation method and application thereof

Abstract

The application belongs to the technical field of semiconductor microelectronic material development and piezoelectric thin film material, and particularly relates to a lead zirconate titanate / lead titanate periodic laminated film, a preparation method and application. The application adopts a sol-gel method combined with an independent rapid annealing strategy for each period to prepare a plurality of periods of PT / PZT laminated films on a Pt / Ti / Si substrate, and sets the annealing temperature to 500-650 DEG C and the time to 2-10 min. The application does not need a buffer layer and element doping, the prepared laminated film has clear period interfaces and controllable crystal orientation, the longitudinal piezoelectric coefficient d 33,f reaches 325 pm / V, the transverse piezoelectric coefficient |e 31,f | reaches 9.8 C / m 2 , the leakage current is lower than 8*10 ‑5 A / cm 2 , and is suitable for piezoelectric MEMS sensors, actuators and energy collectors and the like.

Description

Technical Field

[0001] This invention belongs to the fields of semiconductor microelectronic materials development and piezoelectric thin film materials technology, and specifically relates to a lead zirconate titanate / lead titanate periodic laminated film, its preparation method and application. Background Technology

[0002] Lead zirconate titanate (Pb(Zr,Ti)O3, or PZT for short), as a perovskite-structured lead-based piezoelectric material, has become a crucial basic functional material in the field of piezoelectric devices due to its combination of high piezoelectric coefficient and high Curie temperature near the quasi-isomorphic phase boundary (MPB). However, traditional bulk PZT ceramics or single-crystal materials have limitations such as high intrinsic rigidity, high crystallization temperature, and poor compatibility with CMOS processes, making it difficult to meet the development needs of high-frequency micro and nano devices. Therefore, developing thin-film and low-temperature processing techniques has become an important path to overcome technical bottlenecks.

[0003] In existing technologies, methods for reducing the crystallization temperature and improving the performance of PZT thin films mainly include two approaches: introducing buffer layers and elemental doping. For example, conductive perovskite buffer layers such as LaNiO3 are used to control crystal orientation; and elemental doping with elements such as La and Nb is used to reduce film leakage current, thereby improving piezoelectric properties. However, elemental doping directly complicates the thin film processing; buffer layer technology requires expensive targets for sputtering deposition, significantly increasing manufacturing costs. More importantly, these methods have not effectively reduced the crystallization temperature and often lead to a decrease in the Curie temperature, resulting in limited improvement in piezoelectric properties.

[0004] As piezoelectric MEMS devices continue to evolve towards higher integration and lower crystallization temperatures, the development of lead zirconate titanate films that combine high voltage coefficients, low-temperature fabrication processes, and low dielectric losses has become an urgent need. Therefore, developing a low-cost, simple method for preparing perovskite lead zirconate titanate films that is compatible with low-temperature crystallization and micro / nano fabrication is of significant importance and application value in overcoming existing technological bottlenecks. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a lead zirconate titanate / lead titanate periodic laminated film, its preparation method, and its applications. This invention achieves a method for reducing the crystallization temperature and controlling the crystallographic orientation of lead zirconate titanate films by introducing lead titanate film layers. Specifically, the invention employs a sol-gel spin-coating method. First, a lead titanate film is spin-coated onto a Pt-coated Si substrate. After drying and pyrolysis, several layers of lead zirconate titanate film are then spin-coated. The entire process requires no dopant. Subsequently, the film is annealed. Repeating the spin-coating-annealing process multiple times yields a multi-periodic lead zirconate / lead titanate laminated film. The resulting lead zirconate / lead titanate laminated film exhibits advantages such as high preferred orientation, low coercivity voltage, and excellent ferroelectric and piezoelectric properties, demonstrating significant application potential in the field of perovskite piezoelectric microelectromechanical systems (MEMS).

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention provides a lead zirconate titanate / lead titanate periodic laminated film, the laminated film comprising 1 to 4 cycles, each cycle comprising at least one amorphous lead titanate film layer and at least one amorphous lead zirconate titanate film layer, the amorphous lead titanate film layer and the amorphous lead zirconate titanate film layer being alternately arranged in the film thickness direction to form a periodic layered structure, and each cycle having an independent crystallization interface.

[0007] Preferably, the multilayer film is disposed on a Si substrate or a Si substrate with a SiO2 oxide layer, and a Ti metal bonding layer and a Pt metal electrode layer are disposed sequentially between the substrate and the multilayer film.

[0008] Preferably, the thickness of the multilayer film is 285~1290 nm; the thickness of the Ti metal bonding layer is 30~50 nm; and the thickness of the Pt metal electrode layer is 200~500 nm.

[0009] A second aspect of the present invention provides a method for preparing the lead zirconate titanate / lead titanate periodic laminated film as described in the first aspect, comprising the following steps: A Ti metal bonding layer and a Pt metal electrode layer are sequentially deposited on a Si substrate; Lead titanate precursor solution and lead zirconate titanate precursor solution were prepared by sol-gel method; A lead titanate precursor solution was spin-coated onto the metal Pt electrode layer using a spin coating method, followed by drying and pyrolysis to form an amorphous lead titanate film. A lead zirconate titanate precursor solution was spin-coated onto the lead titanate amorphous film using a spin coating method. After drying and pyrolysis, the lead zirconate titanate amorphous film was formed after repeated spin coating, drying and pyrolysis. This is the lead titanate / lead zirconate titanate amorphous laminate film. The lead titanate / lead zirconate titanate amorphous laminated film is subjected to rapid annealing to obtain a one-cycle lead zirconate titanate / lead titanate crystallized film layer; the deposition of lead zirconate titanate / lead titanate crystallized laminated film is repeated on the lead zirconate titanate / lead titanate crystallized film layer to obtain lead zirconate titanate / lead titanate laminated films with different number of cycles.

[0010] Preferably, a Ti metal binder layer and a Pt metal electrode layer are deposited sequentially on the Si substrate using magnetron sputtering. The specific steps are as follows: The Si substrate was placed in the magnetron sputtering chamber, and the chamber pressure was evacuated to 2 × 10⁻⁶. -4 Pa; introduce argon gas at a flow rate of 20~60 sccm, and modulate the chamber pressure to 0.1~1.0 Pa; raise the substrate temperature to 200~400℃ at a heating rate of 5~10℃ / min; adjust the sputtering power to 50~100 W, and successively sputter and deposit the Ti binder layer and Pt electrode layer to the required thickness.

[0011] Preferably, the preparation method of the lead titanate precursor solution is as follows: Ethylene glycol methyl ether and glacial acetic acid were mixed evenly at a volume ratio of (1~1.3):1 to form a mixed solvent. Then, the required amount of lead acetate trihydrate raw material was weighed and added to the mixed solvent, and stirred until completely dissolved. Subsequently, acetylacetone and tetrabutyl titanate were added in sequence and stirred thoroughly to form a homogeneous solution. Finally, ethylene glycol methyl ether was added to adjust the precursor solution concentration to 0.1~0.3 mol / L, and the solution was stirred at room temperature for 6~12 h and allowed to stand for aging for 24~72 h to obtain the lead titanate precursor solution. The lead acetate trihydrate raw material has a molar excess of 5-20%, and the molar ratio of lead acetate trihydrate to tetrabutyl titanate is (1.05-1.2):1. The amount of acetylacetone used is 1-3 mL. If the molar excess of lead acetate trihydrate is less than 5% or more than 20%, the lead film will deviate from its stoichiometric ratio due to the mismatch in lead volatilization during heat treatment, resulting in impurity phases and damaging the film performance.

[0012] Preferably, the preparation method of the lead zirconate titanate precursor solution is as follows: Ethylene glycol methyl ether and glacial acetic acid were mixed evenly at a volume ratio of (1~1.3):1 to serve as a mixed solvent. Then, the required amount of lead acetate trihydrate raw material was weighed and added to the mixed solvent, and stirred until completely dissolved. Subsequently, acetylacetone, tetrabutyl titanate, and zirconium propoxide raw material were added in sequence and stirred thoroughly to ensure uniform mixing. Finally, ethylene glycol methyl ether was added to adjust the precursor solution concentration to 0.1~0.3 mol / L, and the mixture was stirred at room temperature for 6~12 h and allowed to stand for aging for 24~72 h to obtain the lead zirconate titanate precursor solution. The lead acetate trihydrate raw material has a molar excess of 5-20%, and the molar ratio of lead acetate trihydrate, tetrabutyl titanate, and zirconium propoxide is (1.05-1.2):0.48:0.52. The amount of acetylacetone used is 1-3 mL. If the molar excess of lead acetate trihydrate is less than 5% or more than 20%, the lead film will deviate from its stoichiometric ratio due to the mismatch in lead volatilization during heat treatment, resulting in impurity phases that damage the film's performance.

[0013] Preferably, the spin coating process for both the lead titanate precursor solution and the lead zirconate titanate precursor solution is: low speed 500~1100 rpm, spin coating time 8~15 s, and high speed 3000~5500 rpm, spin coating time 15~30 s.

[0014] Preferably, in the preparation of the lead titanate amorphous film and the lead zirconate titanate amorphous film, the drying temperature is 100~200℃ and the drying time is 1~10 min; the pyrolysis temperature is 300~500℃ and the pyrolysis time is 1~10 min.

[0015] Preferably, the rapid annealing temperature is 500~650℃, the duration is 2~10 min, and the annealing atmosphere is oxygen; the rapid annealing treatment is performed after each cycle of lead titanate amorphous film and lead zirconate titanate amorphous film deposition is completed, and each cycle is annealed independently.

[0016] A third aspect of the present invention provides an application of the lead zirconate titanate / lead titanate periodic laminated film described in the first aspect in a piezoelectric microelectromechanical system (MEMS).

[0017] Preferably, the piezoelectric microelectromechanical system includes a sensor, an actuator, a transducer, a resonator, and an energy harvester.

[0018] The beneficial effects achieved by one or more technical solutions of the present invention are as follows: (1) This invention employs a sol-gel spin-coating method combined with a periodic independent rapid annealing strategy to achieve the medium-low temperature preparation of lead zirconate titanate / lead titanate multilayer piezoelectric films. This preparation method eliminates the need for expensive and complex high-vacuum equipment such as magnetron sputtering and pulsed laser deposition, significantly reducing equipment investment and maintenance costs. At the same time, all raw materials and reagents used are commercially available products with low prices. Compared with the high-cost sputtering targets and expensive single-crystal oxide substrates required by physical vapor deposition methods, it has significant economic advantages and is easy to scale up production.

[0019] (2) The precursor solution composition used in this invention can be precisely controlled, achieving molecular-level homogeneity and effectively reducing component segregation. This ensures that the prepared lead zirconate titanate and lead titanate film materials have uniform composition, accurate stoichiometry, and consistent performance. Furthermore, this invention directly deposits a multilayer film on a Si substrate coated with a Pt electrode, eliminating the need for additional lanthanum nickelate, strontium ruthenate, or other oxide buffer layers, and without any elemental doping. This simplifies the preparation process, further reducing process complexity and manufacturing costs, and facilitating industrial application.

[0020] (3) Compared with non-periodic processes such as one-time annealing or bottom monolayer induction, the periodic structural design of the present invention ensures the successful preparation of high-quality multilayer films and achieves effective control of film crystallization orientation. Specifically, the present invention introduces an alternating arrangement of lead titanate film layers and lead zirconate titanate film layers and adopts an independent annealing process for each cycle, so that each cycle has an independent crystallization interface, thereby effectively releasing the accumulated stress between the film layers and avoiding the problem of film cracking caused by excessive stress.

[0021] (4) The high-voltage lead zirconate titanate / lead titanate laminated film provided by this invention has a low annealing temperature (500~650℃), which is significantly lower than the crystallization temperature (650~750℃) typically required for lead zirconate titanate piezoelectric film materials in existing technologies; and the annealing time is short (only 2~10 min), eliminating the need for a long high-temperature deposition process (methods such as magnetron sputtering and pulsed laser deposition usually require several hours of deposition). This low-temperature short-time annealing process can effectively suppress the volatilization of lead elements and compositional deviation in the film caused by long-term high-temperature heat treatment, avoid the generation of defects such as impurity phases and oxygen vacancies, thereby significantly reducing the leakage current and dielectric loss of the film material and improving the insulation and ferroelectric properties of the film.

[0022] (5) The lead zirconate titanate / lead titanate laminated film material prepared by the present invention has low coercivity voltage (<10 V) and low leakage current density (<8×10 V). -5 A / cm 2 It exhibits excellent properties such as high dielectric constant (1100~1700) and low dielectric loss (<0.1), and especially demonstrates high saturation polarization (80~130 μC / cm). 2 It also boasts high longitudinal piezoelectricity (140~330 pm / V) and transverse piezoelectricity reaching (8~10 C / m). 2 This technology can meet the core requirements of piezoelectric MEMS devices for high-performance piezoelectric films.

[0023] (6) The lead zirconate titanate / lead titanate laminate film prepared by this invention has excellent fatigue resistance properties, and after undergoing 1.8 × 10⁻⁶ cycles, it exhibits excellent fatigue resistance. 6 After the second drive cycle, the transverse piezoelectric coefficient |e 31,fThe decay rate is less than 3.2%, demonstrating good long-term operational stability. Combined with its low-temperature fabrication process and compatibility with CMOS processes, this multilayer film material has broad application prospects in the field of perovskite piezoelectric microelectromechanical systems (MEMS). Attached Figure Description

[0024] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0025] Figure 1 This is a schematic diagram of the lead zirconate titanate / lead titanate periodic stacked film prepared according to the present invention, wherein 1: Si substrate; 2: Ti bonding layer; 3: Pt bottom electrode layer; 4: lead titanate film layer; 5: lead zirconate titanate film layer; 6: lead zirconate titanate / lead titanate periodic stacked film. Figure 2 The XRD patterns are of lead zirconate titanate / lead titanate laminated films with different stacking cycles obtained in Examples 1 and 14-16 of this invention. Figure 3 The images show the scanning electron microscope (SEM) surface morphology of lead zirconate titanate / lead titanate laminated films with different stacking cycles obtained in Examples 1 and 14-16 of this invention. (a) is the SEM surface morphology of the lead zirconate titanate / lead titanate laminated film with one cycle; (b) is the SEM surface morphology of the lead zirconate titanate / lead titanate laminated film with two cycles; (c) is the SEM surface morphology of the lead zirconate titanate / lead titanate laminated film with three cycles; and (d) is the SEM surface morphology of the lead zirconate titanate / lead titanate laminated film with four cycles. Figure 4 The images shown are scanning electron microscope (SEM) cross-sectional images of lead zirconate titanate / lead titanate laminated films with different stacking cycles obtained in Examples 1 and 14-16 of this invention. (a) is an SEM cross-sectional image of lead zirconate titanate / lead titanate laminated film with one cycle; (b) is an SEM cross-sectional image of lead zirconate titanate / lead titanate laminated film with two cycles; (c) is an SEM cross-sectional image of lead zirconate titanate / lead titanate laminated film with three cycles; and (d) is an SEM cross-sectional image of lead zirconate titanate / lead titanate laminated film with four cycles. Figure 5The figures show the hysteresis loops and polarization reversal current curves of lead zirconate titanate / lead titanate multilayer films with different stacking periods obtained in Examples 1 and 14-16 of this invention, wherein (a) is the hysteresis loop and polarization reversal current curve of the lead zirconate titanate / lead titanate multilayer film with one period; (b) is the hysteresis loop and polarization reversal current curve of the lead zirconate titanate / lead titanate multilayer film with two periods; (c) is the hysteresis loop and polarization reversal current curve of the lead zirconate titanate / lead titanate multilayer film with three periods; and (d) is the hysteresis loop and polarization reversal current curve of the lead zirconate titanate / lead titanate multilayer film with four periods. Figure 6 The leakage current density curves of lead zirconate titanate / lead titanate stacked films with different stacking cycles obtained in Examples 1 and 14-16 of this invention are shown. Figure 7 The figures show the dielectric constant and loss curves as a function of frequency for lead zirconate titanate / lead titanate laminated films with different stacking periods obtained in Examples 1 and 14-16 of this invention. (a) shows the dielectric constant-frequency curve and dielectric loss-frequency curve of the lead zirconate titanate / lead titanate laminated film with one period; (b) shows the dielectric constant-frequency curve and dielectric loss-frequency curve of the lead zirconate titanate / lead titanate laminated film with two periods; (c) shows the dielectric constant-frequency curve and dielectric loss-frequency curve of the lead zirconate titanate / lead titanate laminated film with three periods; and (d) shows the dielectric constant-frequency curve and dielectric loss-frequency curve of the lead zirconate titanate / lead titanate laminated film with four periods. Figure 8 The figures show the dielectric constant and loss curves of lead zirconate titanate / lead titanate multilayer films with different stacking periods obtained in Examples 1 and 14-16 of this invention under an applied electric field. (a) shows the dielectric constant-electric field curve and dielectric loss-electric field curve of the lead zirconate titanate / lead titanate multilayer film with one period; (b) shows the dielectric constant-electric field curve and dielectric loss-electric field curve of the lead zirconate titanate / lead titanate multilayer film with two periods; (c) shows the dielectric constant-electric field curve and dielectric loss-electric field curve of the lead zirconate titanate / lead titanate multilayer film with three periods; and (d) shows the dielectric constant-electric field curve and dielectric loss-electric field curve of the lead zirconate titanate / lead titanate multilayer film with four periods. Figure 9 The piezoelectric response amplitude and phase diagrams and the corresponding effective longitudinal piezoelectric coefficient d of lead zirconate titanate / lead titanate laminated films with different stacking periods prepared in Examples 1 and 14-16 of this invention are shown. 33,f The curves (a) represent the piezoelectric amplitude-voltage and phase-voltage curves of the lead zirconate titanate / lead titanate multilayer film over one period; (b) represent the effective longitudinal piezoelectric coefficient d of the lead zirconate titanate / lead titanate multilayer film over one period. 33,f(c) shows the piezoelectric amplitude-voltage curve and phase-voltage curve of the lead zirconate titanate / lead titanate laminated film for two cycles; (d) shows the effective longitudinal piezoelectric coefficient d of the lead zirconate titanate / lead titanate laminated film for two cycles. 33,f (e) shows the piezoelectric amplitude-voltage and phase-voltage curves of the lead zirconate titanate / lead titanate multilayer film for three periods; (f) shows the effective longitudinal piezoelectric coefficient d of the lead zirconate titanate / lead titanate multilayer film for three periods. 33,f Curves; (g) show the piezoelectric amplitude-voltage and phase-voltage curves of the lead zirconate titanate / lead titanate multilayer film for four periods; (h) shows the effective longitudinal piezoelectric coefficient d of the lead zirconate titanate / lead titanate multilayer film for four periods. 33,f curve; Figure 10 The transverse piezoelectric coefficient e of the cantilever beams with lead zirconate titanate / lead titanate laminated films having different stacking periods prepared in Examples 1 and 15-16 of this invention is shown. 31,f The driving cycle curves are shown, where (a) is the transverse piezoelectric coefficient e of the lead zirconate titanate / lead titanate stacked film over two cycles. 31,f - Electric field curves and displacement-voltage curves at the tip of the cantilever beam; (b) Transverse piezoelectric coefficient e of the lead zirconate titanate / lead titanate laminate film for two cycles. 31,f - Drive cycle count curve and cantilever beam tip displacement - Drive cycle count curve; (c) is the transverse piezoelectric coefficient e of the lead zirconate titanate / lead titanate laminate film during three cycles. 31,f - Electric field curves and displacement-voltage curves at the tip of the cantilever beam; (d) is the transverse piezoelectric coefficient e of the lead zirconate titanate / lead titanate laminate film during three cycles. 31,f - Drive cycle count curve and cantilever beam tip displacement - Drive cycle count curve; (e) is the transverse piezoelectric coefficient e of the lead zirconate titanate / lead titanate laminate film during four cycles. 31,f - Electric field curves and displacement-voltage curves at the tip of the cantilever beam; (f) is the transverse piezoelectric coefficient e of the lead zirconate titanate / lead titanate laminate film during four cycles. 31,f -Drive cycle count curve and cantilever beam tip displacement-Drive cycle count curve; Figure 11 This is a photograph of the actual cracking process of the lead zirconate titanate / lead titanate laminated film prepared in Comparative Example 1 of the present invention. Figure 12 The XRD pattern of the lead zirconate titanate / lead titanate laminate film prepared in Comparative Example 2 of this invention; Figure 13 This is a scanning electron microscope (SEM) image of the surface of the lead zirconate titanate / lead titanate laminate film prepared in Comparative Example 6 of the present invention. Figure 14 This is a photograph of the actual cracking process of the lead zirconate titanate / lead titanate laminated film prepared in Comparative Example 7 of the present invention. Detailed Implementation

[0026] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0027] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are explanations of the present invention and not limitations thereof.

[0028] Example 1: This example provides a lead zirconate titanate / lead titanate periodic laminated film and its preparation method. The preparation method includes the following steps: (1) Substrate treatment and bottom electrode preparation Semiconductor Si or Si with a SiO2 oxide layer was used as the substrate. The substrate was ultrasonically cleaned with anhydrous ethanol, dried with high-purity nitrogen, and then placed in a magnetron sputtering chamber. A vacuum was then evacuated until the chamber pressure reached 2 × 10⁻⁶. -4 Pa; Argon gas was introduced and the argon gas flow rate was adjusted to 40 sccm, and the chamber pressure was adjusted to 0.3 Pa. The substrate temperature was raised to 300℃ at a heating rate of 5℃ / min; Ti and Pt metal layers were sequentially deposited on the Si substrate using radio frequency magnetron sputtering technology. The sputtering power was 55 W, and the deposition time was controlled to be 5 min and 15 min, respectively. The Pt layer was the bottom electrode layer with a thickness of 360 nm, and the Ti layer was used as a bonding layer to enhance the bonding force between the Si substrate and the Pt electrode layer with a thickness of 35 nm.

[0029] (2) Preparation of lead titanate precursor solution Taking the preparation of a lead titanate precursor with a concentration of 0.2 mol / L and a volume of 30 mL as an example, 10 mL of ethylene glycol methyl ether and 8 mL of glacial acetic acid were mixed evenly (volume ratio 1.2:1) to prepare a mixed solvent. According to the stoichiometric ratio, 2.52 g of lead acetate trihydrate required for preparing the PbTiO3 precursor solution and 2 mL of tetrabutyl titanate were weighed, with a 10% excess of Pb (i.e., a Pb / Ti molar ratio of 1.1:1). Then, the lead acetate trihydrate raw material was added to the above mixed solvent and stirred at room temperature until completely dissolved. Subsequently, 2.5 mL of acetylacetone (stabilizer) was added, followed by the tetrabutyl titanate solution, and the mixture was stirred thoroughly until homogeneous. Finally, 7.5 mL of ethylene glycol methyl ether was added to adjust the precursor solution concentration to 0.2 mol / L, and the mixture was stirred at room temperature for 10 h and allowed to stand for aging for 48 h before use.

[0030] (3) Preparation of lead zirconate titanate precursor solution Taking the preparation of a 0.2 mol / L, 30 mL lead zirconate titanate precursor as an example, 10 mL of ethylene glycol methyl ether and 8 mL of glacial acetic acid are mixed thoroughly to prepare a mixed solvent. Based on the stoichiometric ratio, the amount of lead zirconate titanate (Pb(Zr)) to be prepared is weighed... 0.52 Ti 0.48 2.52 g of lead acetate trihydrate was prepared for the O3 precursor solution, along with 1 mL of tetrabutyl titanate and 1.5 mL of zirconium propoxide solution, wherein the molar content of Pb was in excess by 10% (i.e., the Pb / (Zr+Ti) molar ratio was 1.1:1). Then, lead acetate trihydrate was added to the above mixed solvent and stirred at room temperature until completely dissolved. Subsequently, 2.5 mL of acetylacetone was added, followed by tetrabutyl titanate and zirconium propoxide, and the mixture was stirred thoroughly. Finally, 7 mL of ethylene glycol methyl ether was added to adjust the precursor solution concentration to 0.2 mol / L. The mixture was stirred at room temperature for 10 h and then allowed to stand for 48 h to age.

[0031] (4) Preparation of lead zirconate titanate / lead titanate periodic laminated film (spin-coating method): 1) The lead titanate precursor solution synthesized in step (2) is dropped onto the Si substrate in step (1) to uniformly cover the entire surface of the Si substrate. Then, an amorphous lead titanate film is obtained by spin coating, drying, and pyrolysis. The spin coating process is as follows: low speed is 800 rpm and spin coating time is 12 s; high speed is 4500 rpm and spin coating time is 20 s. After spin coating, the substrate is subjected to drying heat treatment at a temperature of 150℃ for 3 min. After drying heat treatment, pyrolysis treatment is performed at a temperature of 450℃ for 3 min. After pyrolysis, an amorphous lead titanate film is formed on the Pt layer.

[0032] 2) The lead zirconate titanate precursor solution synthesized in step (3) is dropped onto the lead titanate film layer to uniformly cover the entire surface of the lead titanate film layer. Then, spin coating, drying and pyrolysis are performed. The spin coating process is as follows: low speed of 800 rpm and spin coating time of 12 s; high speed of 4500 rpm and spin coating time of 20 s. After spin coating, the substrate is dried and heat-treated at a temperature of 150℃ for 3 min. After drying and heat treatment, pyrolysis is performed at a temperature of 450℃ for 3 min. The above "spin coating-drying-pyrolysis" steps are repeated 8 times to form an amorphous lead zirconate titanate film layer on the lead titanate amorphous film layer. The whole is a lead titanate / lead zirconate titanate amorphous laminated film.

[0033] 3) The lead titanate / lead zirconate titanate amorphous laminated film obtained above is subjected to rapid annealing in an oxygen atmosphere at an annealing temperature of 575℃ and an annealing time of 3 min to obtain a crystallized lead zirconate titanate / lead titanate laminated film of one cycle. 4) The preparation of the lead zirconate titanate / lead titanate crystallized laminated film was repeated three times. That is, the PT / PZT laminates of the second and third periods were sequentially deposited on the lead zirconate titanate / lead titanate crystallized laminated film of the first period and annealed respectively, thus obtaining a periodic lead zirconate titanate / lead titanate laminated film material with three periods. The thickness of a single PT layer is about 30 nm, and the total thickness of the 8 PZT layers is about 280 nm.

[0034] Example 2: The difference between this embodiment and Embodiment 1 is that: in step (2), the molar content of Pb element in the PbTiO3 precursor solution is 15% excess, that is, the Pb:Ti molar ratio is 1.15:1; in step (3), Pb(Zr) 0.52 Ti 0.48 The molar content of Pb in the O3 precursor solution was 15% excess, that is, the molar ratio of Pb:Zr:Ti was 1.15:0.52:0.48; the content of other components and the preparation method were the same as in Example 1.

[0035] Example 3: The difference between this embodiment and Embodiment 1 is that in steps (2) and (3), the PbTiO3 precursor solution and Pb(Zr) 0.52 Ti 0.48 The concentration of the O3 precursor solution was 0.1 mol / L, and the content of other components and the preparation method were the same as in Example 1.

[0036] Example 4: The difference between this embodiment and Embodiment 1 is that in steps (2) and (3), the PbTiO3 precursor solution and Pb(Zr) 0.52 Ti 0.48 The concentration of the O3 precursor solution was 0.3 mol / L, and the content of other components and the preparation method were the same as in Example 1.

[0037] Example 5: The difference between this embodiment and embodiment 1 is that in step (4), the spin coating process involved in the preparation of the lead titanate amorphous film and the lead zirconate titanate amorphous film is: the low rotation speed is replaced with 500 rpm and the spin coating time is 15 s, the high rotation speed conditions remain unchanged, and the content of other components and the preparation method are the same as in embodiment 1.

[0038] Example 6: The difference between this embodiment and embodiment 1 is that in step (4), the spin coating process involved in the preparation of the lead titanate amorphous film and the lead zirconate titanate amorphous film is: the low rotation speed is replaced with 1000 rpm and the spin coating time is 9 s, the high rotation speed conditions remain unchanged, and the content of other components and the preparation method are the same as in embodiment 1.

[0039] Example 7: The difference between this embodiment and embodiment 1 is that in step (4), the spin coating process involved in the preparation of the lead titanate amorphous film and the lead zirconate titanate amorphous film is as follows: the low speed condition remains unchanged, the high speed is replaced by 3500 rpm, the spin coating time is 30 s, and the content of other components and the preparation method are the same as in embodiment 1.

[0040] Example 8: The difference between this embodiment and embodiment 1 is that in step (4), the spin coating process involved in the preparation of the lead titanate amorphous film and the lead zirconate titanate amorphous film is as follows: the low speed condition remains unchanged, the high speed is replaced by 5500 rpm, the spin coating time is 15 s, and the content of other components and the preparation method are the same as in embodiment 1.

[0041] Example 9: The difference between this embodiment and embodiment 1 is that in step (4), the drying heat treatment process involved in the preparation of the lead titanate amorphous film and the lead zirconate titanate amorphous film is: the drying temperature is 200℃ and the drying time is 2 min. The content of other components and the preparation method are the same as in embodiment 1.

[0042] Example 10: The difference between this embodiment and embodiment 1 is that in step (4), the pyrolysis process involved in the preparation of the lead titanate amorphous film and the lead zirconate titanate amorphous film is: the pyrolysis temperature is 400 ℃ and the pyrolysis time is 5 min. The content of other components and the preparation method are the same as in embodiment 1.

[0043] Example 11: The difference between this embodiment and embodiment 1 is that in step (4), the annealing temperature of the lead titanate / lead zirconate titanate amorphous laminated film is 625°C and the annealing time is 5 min. The content of other components and the preparation method are the same as in embodiment 1.

[0044] Example 12: The difference between this embodiment and Example 1 is that in step (4), the lead zirconate titanate precursor solution is repeatedly "spin-coated-dried-pyrolyzed" 6 times to obtain an amorphous lead zirconate titanate film layer, and the content of other components and preparation methods are the same as in Example 1.

[0045] Example 13: The difference between this embodiment and Example 1 is that in step (4), the lead zirconate titanate precursor solution is repeatedly "spin-coated-dried-pyrolyzed" 7 times to obtain an amorphous lead zirconate titanate film layer, while the content of other components and the preparation method are the same as in Example 1.

[0046] Example 14: The difference between this embodiment and embodiment 1 is that in step (4), the cycle is not repeated, that is, only one cycle of lead zirconate titanate / lead titanate laminated film material is obtained, and the content of other components and the preparation method are the same as in embodiment 1.

[0047] Example 15: The difference between this embodiment and embodiment 1 is that in step (4), steps 1) to 3) are repeated twice to obtain two cycles of lead zirconate titanate / lead titanate laminated film material. The content of other components and the preparation method are the same as in embodiment 1.

[0048] Example 16: The difference between this embodiment and embodiment 1 is that in step (4), steps 1) to 3) are repeated 4 times to obtain 4 cycles of lead zirconate titanate / lead titanate laminated film material. The content of other components and the preparation method are the same as in embodiment 1.

[0049] Comparative Example 1: (One-time annealing, not independent annealing in each cycle) The difference between this comparative example and Example 1 is that in step (4), steps 1) to 3) are repeated 3 times (i.e., a complete 3-cycle amorphous PT / PZT stack is deposited, with a total of 3 PT layers and 24 PZT layers). During the deposition of each amorphous layer, only drying and pyrolysis treatment are performed, and no annealing treatment is performed. After all amorphous layers are deposited, a final rapid annealing treatment is performed in an oxygen atmosphere. The annealing temperature is 575℃ and the annealing time is 3 min. The content of other components and the preparation method are the same as in Example 1.

[0050] During this comparative implementation, when the second cycle of the PT / PZT laminated film was spin-coated, the laminated film immediately cracked completely (e.g. Figure 11 As shown in the figure, spin coating could not continue, so the comparative example could not successfully prepare a multilayer film.

[0051] Comparative Example 2: (bottom monolayer PT-induced, PZT one-time deposition) The difference between this comparative example and Example 1 is that in step (4), only one layer of PT amorphous layer is first deposited on the Pt layer (using the PT spin coating process of Example 1, the total thickness of the PT layer is equivalent to the sum of the thicknesses of the PT layers in 3 cycles in Example 1), and the PT layer is subjected to rapid annealing treatment (575℃ / 3 min) to form a crystallized PT seed layer; then all PZT layers are deposited on the PT seed layer at once (using the PZT spin coating process of Example 1, repeating "spin coating-drying-pyrolysis" 24 times), and finally a final rapid annealing is performed (575℃ / 3 min). The content of other components and the preparation method are the same as in Example 1.

[0052] In this comparative implementation, the PT layer is essentially deposited entirely at the bottom. This significantly weakens the effect of PT on inducing the crystallographic orientation of the PZT film on top and reducing the crystallization temperature, resulting in weaker crystallization of the laminated film (e.g., Figure 12 As shown, apart from the diffraction peaks of the Pt bottom electrode and the Si substrate, no obvious diffraction peaks were observed in the PZT / PT stack film. The performance degradation was severe, and effective electrical performance could not be tested.

[0053] Comparative Example 3: (Bottom monolayer PT-induced, PZT stepwise deposition, one-time annealing) The difference between this comparative example and Example 1 is that in step (4), only one layer of PT amorphous layer is first deposited on the Pt layer (the total thickness of the PT layer is equivalent to the sum of the thicknesses of the PT layers in 3 cycles in Example 1), and the PT layer is subjected to rapid annealing treatment (575℃ / 3 min) to form a crystallized PT seed layer; then, PZT layers are deposited stepwise on the PT seed layer, and after every 8 layers of PZT are deposited (each layer is subjected to "spin-coating-drying-pyrolysis"), drying and pyrolysis treatment are performed, which is repeated 3 times in total (the total number of PZT layers is 24 layers, the same as in Example 1), and no annealing treatment is performed in each stage; after all PZT layers are deposited, a final rapid annealing treatment (575℃ / 3 min) is performed, and the content of other components and preparation methods are the same as in Example 1.

[0054] Similar to Comparative Example 2, in this comparative example, the PT layer is essentially deposited at the bottom. Although the PZT film on top undergoes three annealing processes, it is still essentially deposited at the top. This also significantly weakens the effect of PT on inducing the growth orientation of the PZT film layer on top and reducing the crystallization temperature, which in turn leads to weaker crystallization of the laminated film and performance degradation.

[0055] Comparative Example 4: The difference between this comparative example and Example 1 is that in step (4), the annealing temperature of the lead titanate / lead zirconate titanate amorphous laminated film is 450°C, while the content of other components and the preparation method are the same as in Example 1.

[0056] In this comparative example, if the annealing temperature is low, such as below 500℃, the PT / PZT laminated film cannot crystallize (similar to Comparative Example 2), and therefore does not have electrical properties.

[0057] Comparative Example 5: The difference between this comparative example and Example 1 is that in step (4), the annealing temperature of the lead titanate / lead zirconate titanate amorphous laminated film is 700°C, while the content of other components and the preparation method are the same as in Example 1.

[0058] In this comparative process, if the annealing temperature is too high, such as above 650℃, the lead content in the PT / PZT laminated film will be severely lost through volatilization, deviating from the stoichiometry, and easily generating impurities, which will degrade its electrical properties and make it impossible to measure effective piezoelectric properties.

[0059] Comparative Example 6: The difference between this comparative example and Example 1 is that in steps (2) and (3), the PbTiO3 precursor solution and Pb(Zr) are used. 0.52 Ti 0.48 The concentration of the O3 precursor solution was 0.05 mol / L, and the content of other components and the preparation method were the same as in Example 1.

[0060] In this comparative experiment, if the precursor concentration is low, such as below 0.1 mol / L, the solution is too dilute, resulting in poor film density and a tendency to form pores during spin-coating onto the substrate surface (e.g., Figure 13 As shown in the figure, it was impossible to successfully prepare a high-quality multilayer membrane.

[0061] Comparative Example 7: Unlike Example 1, in steps (2) and (3), the PbTiO3 precursor solution and Pb(Zr) are used in steps (2) and (3). 0.52 Ti 0.48 The concentration of the O3 precursor solution was 0.5 mol / L, and the content of other components and the preparation method were the same as in Example 1.

[0062] In this comparative example, if the precursor concentration is high, such as above 0.4 mol / L, the precursor solution is prone to forming flocculent precipitates; and because the solution is relatively viscous, it is difficult to spin-coat onto the substrate surface, which can easily lead to cracking of the film during heat treatment (e.g. Figure 14 As shown in the figure, it was impossible to successfully prepare a high-quality multilayer membrane.

[0063] Experimental Example 1: This experimental example performs structural tests on the lead zirconate titanate / lead titanate periodic laminated films prepared in the examples and comparative examples. like Figure 1 The diagram shows a schematic of the periodic lead zirconate titanate / lead titanate laminated film prepared by the present invention, including four types of lead zirconate titanate / lead titanate laminated films with 1, 2, 3, and 4 cycles; wherein, the three-cycle lead zirconate titanate / lead titanate laminated film is Example 1 of the present invention, and the one-, two-, and four-cycle lead zirconate titanate / lead titanate laminated films are Examples 14 to 16 of the present invention, respectively.

[0064] like Figure 2The figure shows the XRD patterns of the lead zirconate titanate / lead titanate stacked films prepared in Examples 1 and 14-16. It can be seen that as the number of stacked periods increases from one period to four periods, the diffraction peaks of the stacked film gradually change from a preferred orientation of (001) to a random orientation of multiple diffraction peaks of (001) / (110) / (111) / (211), indicating that the degree of preferred orientation of the film decreases with the increase of the number of periods.

[0065] like Figure 3 As shown in (a) to (d), these are scanning electron microscope images of the surface morphology of the lead zirconate titanate / lead titanate laminated films prepared in Examples 1 and 14 to 16. Uniform and dense grains can be observed in all of them.

[0066] like Figure 4 As shown in (a) to (d), these are scanning electron microscope cross-sectional images of the lead zirconate titanate / lead titanate laminated films prepared in Examples 1 and 14 to 16. It can be observed that the thicknesses of the four laminated films are 285 nm, 694 nm, 944 nm and 1290 nm, respectively, and all four film materials exhibit a clear periodic layered structure.

[0067] Experimental Example 1: This experimental example tests the structural properties of the lead zirconate titanate / lead titanate periodic laminated films prepared in the examples and comparative examples. Testing process: Polarization intensity and leakage current testing: The lead zirconate titanate / lead titanate multilayer film sample was placed on the probe stage of the ferroelectric testing instrument for polarization intensity and leakage current density testing. The test conditions were: maximum applied voltage as the sample can withstand, frequency of 2 kHz, and the top electrode used was a gold dot with an area of ​​0.000314 cm². 2 .

[0068] Dielectric constant and loss test: The lead zirconate titanate / lead titanate laminate film sample was placed on the fixture of the dielectric impedance analyzer for testing; the test conditions were: the probe AC ​​voltage was 1 V, the test frequency range was 20 Hz ~ 2 MHz, and the top electrode used was a gold dot with an area of ​​0.000314 cm². 2 .

[0069] Longitudinal piezoelectric coefficient d 33,f Testing: The lead zirconate titanate / lead titanate multilayer film sample was placed on the probe stage of a piezoelectric response force microscope to measure the piezoelectric amplitude and phase loop. d was calculated from the piezoelectric amplitude and phase loop. 33,f The test conditions are: apply a DC bias voltage of ±20 V and apply a probe drive voltage of 1 V (peak-to-peak).

[0070] Transverse piezoelectric coefficient e 31,fTest: The cantilever beam sample of lead zirconate titanate / lead titanate laminate film was placed on the fixture of the Doppler laser testing system to test the displacement of the cantilever beam tip. The value of e was calculated from the displacement of the cantilever beam tip. 31,f The test conditions are: applied AC voltage range of 2~30 V (peak-to-peak) and AC voltage frequency of 500 Hz.

[0071] The specific test results are shown in Table 1: Table 1

[0072] As can be seen from the data in Table 1, although the performance of the PZT / PT multilayer membranes in all embodiments of the present invention fluctuates, they all exhibit the corresponding electrical properties; while the embodiments in the comparative examples failed to successfully prepare high-quality multilayer membranes or failed to measure the relevant electrical properties.

[0073] Specifically, such as Figure 5 As shown in (a) to (d), the ferroelectric properties of the lead zirconate titanate / lead titanate laminated films prepared in Examples 1 and 14-16 are shown, with saturation polarization intensities of 130 μC / cm. 2 93 μC / cm 2 122 μC / cm 2 97 μC / cm 2 The remanent polarization intensities were 73 μC / cm. 2 45 μC / cm 2 62 μC / cm 2 49 μC / cm 2 In addition, the polarization current curves of these multilayer films all show two distinct reversal current peaks, indicating that they have excellent ferroelectric polarization reversal performance (the black curve represents the hysteresis loop, and the red curve represents the polarization reversal current curve).

[0074] like Figure 6 The figure shows the leakage current curves of the lead zirconate titanate / lead titanate laminated films prepared in Examples 1 and 14-16. It can be observed that with the increase of the number of laminated cycles, the leakage current density of the lead zirconate titanate / lead titanate film material shows a gradual decreasing trend, and the leakage current density of all laminated films is less than 3 × 10⁻⁶. -5 A / cm 2 .

[0075] like Figure 7Figures (a) to (d) show the dielectric constant and loss curves of the lead zirconate titanate / lead titanate laminated film materials prepared in Examples 1 and 14-16 as a function of frequency. It can be seen that these four film materials have high dielectric constants and low dielectric losses. At a test frequency of 1 MHz, their dielectric constants are 1709, 1079, 1568, and 1428, respectively, and their losses are 4.5%, 9.0%, 7.5%, and 4.6%, respectively (the black curve represents the dielectric constant-frequency curve, and the red curve represents the dielectric loss-frequency curve).

[0076] like Figure 8 As shown in (a) to (d), the dielectric constant and loss of the lead zirconate titanate / lead titanate multilayer film materials prepared in Examples 1 and 14 to 16 are curves showing the variation with the applied electric field. It can be seen that all four multilayer film materials exhibit significant "butterfly-shaped" curves, which again demonstrates that they have excellent polarization reversal characteristics, as well as high dielectric constant and low dielectric loss (the black curve represents the dielectric constant-electric field curve, and the red curve represents the dielectric loss-electric field curve).

[0077] like Figure 9 As shown in (a) to (h), the longitudinal piezoelectric response amplitude, phase diagram, and corresponding effective longitudinal piezoelectric coefficient d of the lead zirconate titanate / lead titanate laminated films prepared in Examples 1 and 14-16 are presented. 33,f It can be observed that all four film materials exhibit significant "butterfly-shaped" piezoelectric amplitude curves and approximately 180° phase reversal, indicating excellent domain reversal characteristics; the calculated effective longitudinal piezoelectric coefficient d of the above four stacked films is shown. 33,f The values ​​are 325 pm / V, 159 pm / V, 211 pm / V, and 169 pm / V, respectively (the black curve represents the piezoelectric amplitude-voltage curve, and the red curve represents the phase-voltage curve).

[0078] like Figure 10 As shown in (a) to (f), the tip displacement and transverse piezoelectric coefficient |e of the cantilever beam of the lead zirconate titanate / lead titanate laminated film materials prepared in Examples 1 and 15-16 are shown. 31,f As can be seen from the driving cycle curves, compared to Example 15, the lead zirconate titanate / lead titanate laminated films in Examples 1 and 16 have higher transverse piezoelectric coefficients, and their saturation |e 31,f The values ​​are as high as 9.8 C / cm. 2 and 8.2 C / m 2 (The black curve represents the transverse piezoelectric coefficient e) 31,f - Electric field curve, the red curve represents the displacement-voltage curve at the tip of the cantilever beam). Meanwhile, after undergoing 1.8×10 6 After the next driving cycle, its transverse piezoelectric coefficient e31,f Value decay rate (Δ|e) 31,f The leakage current density and dielectric loss of the lead zirconate titanate / lead titanate laminated film material prepared in Example 14 were less than 1.5% and 3.2%, respectively, and the attenuation rate (Δδ) of the displacement δ at the tip of the cantilever beam was less than 1.4% and 3.2%, respectively. It should be noted that, due to the relatively high leakage current density and dielectric loss of the lead zirconate titanate / lead titanate laminated film material prepared in Example 14, no effective transverse piezoelectric signal (the green curve represents the transverse piezoelectric coefficient e) was measured. 31,f - Drive cycle count curve, the red curve represents the displacement at the tip of the cantilever beam - drive cycle count curve).

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A lead zirconate titanate / lead titanate periodic laminated film, characterized in that, The laminated film consists of 1 to 4 cycles, each cycle including at least one amorphous lead titanate film layer and at least one amorphous lead zirconate titanate film layer. The amorphous lead titanate film layer and the amorphous lead zirconate titanate film layer are arranged alternately in the film thickness direction to form a periodic layered structure, and each cycle has an independent crystallization interface.

2. The lead zirconate titanate / lead titanate periodic laminated film according to claim 1, characterized in that, The stacked film is disposed on a Si substrate or a Si substrate with a SiO2 oxide layer, and a Ti metal bonding layer and a Pt metal electrode layer are disposed sequentially between the substrate and the stacked film.

3. The lead zirconate titanate / lead titanate periodic laminated film according to claim 2, characterized in that, The thickness of the laminated film is 285~1290 nm; the thickness of the Ti metal bonding layer is 30~50 nm; and the thickness of the Pt metal electrode layer is 200~500 nm.

4. A method for preparing a lead zirconate titanate / lead titanate periodic laminated film according to any one of claims 1 to 3, characterized in that, Includes the following steps: A Ti metal bonding layer and a Pt metal electrode layer are sequentially deposited on a Si substrate; Lead titanate precursor solution and lead zirconate titanate precursor solution were prepared by sol-gel method; A lead titanate precursor solution was spin-coated onto the metal Pt electrode layer using a spin coating method, followed by drying and pyrolysis to form an amorphous lead titanate film. A lead zirconate titanate precursor solution was spin-coated onto the lead titanate amorphous film using a spin coating method. After drying and pyrolysis, the lead zirconate titanate amorphous film was formed after repeated spin coating, drying and pyrolysis. This is the lead titanate / lead zirconate titanate amorphous laminate film. The lead titanate / lead zirconate titanate amorphous laminated film is subjected to rapid annealing to obtain a cycle of lead zirconate titanate / lead titanate crystallized film. The deposition of lead zirconate titanate / lead titanate crystallized films was repeated on the lead zirconate titanate / lead titanate crystallized film layer to obtain lead zirconate titanate / lead titanate stacked films with different number of cycles.

5. The preparation method according to claim 4, characterized in that, A Ti metal binder layer and a Pt metal electrode layer were sequentially deposited on the Si substrate using magnetron sputtering. The specific steps are as follows: The Si substrate was placed in the magnetron sputtering chamber, and the chamber pressure was evacuated to 2 × 10⁻⁶. -4 Pa; introduce argon gas at a flow rate of 20~60 sccm, and modulate the chamber pressure to 0.1~1.0 Pa; raise the substrate temperature to 200~400℃ at a heating rate of 5~10℃ / min; adjust the sputtering power to 50~100 W, and successively sputter and deposit the Ti binder layer and Pt electrode layer to the required thickness.

6. The preparation method according to claim 4, characterized in that, The preparation method of the lead titanate precursor solution is as follows: Ethylene glycol methyl ether and glacial acetic acid were mixed evenly at a volume ratio of (1~1.3):1 to form a mixed solvent. Then, the required amount of lead acetate trihydrate raw material was weighed and added to the mixed solvent, and stirred until completely dissolved. Subsequently, acetylacetone and tetrabutyl titanate were added in sequence and stirred thoroughly to form a homogeneous solution. Finally, ethylene glycol methyl ether was added to adjust the precursor solution concentration to 0.1~0.3 mol / L, and the solution was stirred at room temperature for 6~12 h and allowed to stand for aging for 24~72 h to obtain the lead titanate precursor solution. The lead acetate trihydrate raw material has an excess content of 5-20% in molar amount; the molar ratio of lead acetate trihydrate raw material to tetrabutyl titanate is (1.05-1.2):1; and the amount of acetylacetone used is 1-3 mL.

7. The preparation method according to claim 4, characterized in that, The preparation method of the lead zirconate titanate precursor solution is as follows: Ethylene glycol methyl ether and glacial acetic acid were mixed evenly at a volume ratio of (1~1.3):1 to form a mixed solvent. Then, the required amount of lead acetate trihydrate raw material was weighed and added to the mixed solvent, and stirred until completely dissolved. Subsequently, acetylacetone, tetrabutyl titanate and zirconium propoxide raw material were added in sequence and stirred thoroughly to form a homogeneous mixture. Finally, ethylene glycol methyl ether was added to adjust the precursor solution concentration to 0.1~0.3 mol / L, and the mixture was stirred at room temperature for 6~12 h and allowed to stand for aging for 24~72 h to obtain the lead zirconate titanate precursor solution. The lead acetate trihydrate raw material has an excess content of 5% to 20% in molar amount; the molar ratio of lead acetate trihydrate raw material, tetrabutyl titanate and zirconium propoxide is (1.05~1.2):0.48:0.52, and the amount of acetylacetone used is 1~3 mL.

8. The preparation method according to claim 4, characterized in that, The spin coating process for both the lead titanate precursor solution and the lead zirconate titanate precursor solution is as follows: low speed 500~1100 rpm, spin coating time 8~15 s, high speed 3000~5500 rpm, spin coating time 15~30 s. In the preparation of the lead titanate amorphous film and the lead zirconate titanate amorphous film, the drying temperature is 100~200℃ and the drying time is 1~10 min; the pyrolysis temperature is 300~500℃ and the pyrolysis time is 1~10 min.

9. The preparation method according to claim 4, characterized in that, The rapid annealing temperature is 500~650℃, the duration is 2~10 min, and the annealing atmosphere is oxygen; the rapid annealing treatment is performed after each cycle of lead titanate amorphous film and lead zirconate titanate amorphous film deposition is completed, and each cycle is annealed independently.

10. The application of the lead zirconate titanate / lead titanate periodic laminated film according to any one of claims 1 to 3 in a piezoelectric microelectromechanical system.

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