Fabrication And Characterization Of Flexible Ferroelectric/Antiferroelectric Thin Films

Ferroelectric and anti-ferroelectric materials are multi-purpose due to the properties of dielectric,piezoelectric,pyroelectric,and ferroelectric.They are widely used in micro-actuators,random access memories,energy storage capacitors,refrigerators and other electronic devices.On the other hand,with the emergence of the Internet of Things,there is an increasing demand for miniaturization,ultra-thinness and 3D bendability of electronic devices.Flexible manufacturing has emerged.The the current development prospect and challenge of flexible manufacturing is preparation of electronic devices with excellent mechanical bending properties and excellent electrical properties.The preparation of ferroelectric/antiferroelectric flexible films,electrical performance testing and reliability verification was studied.In this paper,Pb_0.97La_0.02Zr_0.95Ti_0.05O₃(PLZT)antiferroelectric thin films were prepared on sapphire substrate by sol-gel method.Then,they were flexibly processed by controlled spalling technology.The polarization of the film is about 86.3?C/cm² under different tensile or compressive bending radii,showing excellent mechanical stability.It is worth mentioning that the recoverable energy storage density(W_re)of flexible film is 21%higher than that of the original substrate at 500 k V/cm,which is caused by stress changes.At the same time,the hysteresis loop of the flexible film is measured in a wide temperature range of-70°C-200°C and the energy storage density is calculated to fluctuate between 9.2 J/cm³-17.1 J/cm³,which is related to free energy barrier of the phase change.The adiabatic temperature change of-9.5K at-70°C was calculated under the electric field of 500 k V/cm.Further,a bismuth ferrite(Be Fe O₃,BFO)film was prepared on strontium titanate(Sr Ti O₃,STO)substrate by pulsed laser deposition.Domain structure of the film is characterized by piezoelectric force microscope(PFM).The flexible Be Fe O₃film is obtained by the same flexible processing method.The test shows that the domain structure of the flexible BFO film can be retained.It is found that the structure and electrical properties of the flexible ferroelectric/antiferroelectric film prepared by the controllable spalling technology is not damaged.Dry etching can effectively avoid the damage of functional materials.The flexible film can be stretched and compressed with a radiis of 3.5 mm-5 mm.In addition,research has found that the polarization value of the film can be increased and the electrical properties of the material was enhanced effectively due to the stress adjustment of the substrate.The flexible PLZT film has a certain degree of reliability in the temperature range of-70 to 200°C.The flexible BFO film maintain the original microdomain structure.The above research is of great significance to the preparation and application of flexible film materials in flexible electronic devices.