硅酸盐学报2025，Vol.53Issue(9)：2441-2451,11.DOI:10.14062/j.issn.0454-5648.20250289
织构诱发柔性BiFeO3薄膜自极化性能调控
Texture-Induced Self-Polarization of Flexible BiFeO3 Thin Films
摘要
Abstract
Introduction Conventional poling methods,such as contact poling and corona poling,are frequently hampered by susceptibility to dielectric breakdown and film failure.Achieving self-poling without external poling procedure required in lead-free ferroelectric thin films is critical for advancing flexible piezoelectric devices.Here,we introduce a LaNiO3 seed layer on flexible mica substrates to induce(001)-textured BiFeO3 films for self-poling,while systematically evaluating the impact of Mn doping on film properties.The resulting self-poled BiFeO3 films achieve a piezoelectric coefficient d33,d≈50 pC/N and demonstrate exceptional bending stability,retaining over 90%of their initial d33,d after more than 5000 bending cycles.This work presents a compelling new pathway for the development of high-performance lead-free flexible ferroelectric devices. Methods Mica substrates were prepared via blade-cleaving,followed by sequential 3-minute ultrasonic cleaning in anhydrous ethanol,acetone,and anhydrous ethanol to remove contaminants.LaNiO3 solution was synthesized by sol-gel processing:stoichiometric lanthanum nitrate and nickel acetate(La:Ni=1:1 mol ratio,0.2 mol/L concentration)were dissolved in glacial acetic acid with stirring at 80℃until complete dissolution,then stirred for 2 h at 25℃.The solution was aged for 48 h at 25℃.Subsequently,LaNiO3 solution was spin-coated onto mica substrates at 5000 rpm,dried on a hotplate at 150℃,and thermally processed in a rapid thermal annealing furnace under air atmosphere.This involved a pyrolysis step at 400℃for 5 min,followed by crystallization at 700℃for 1 min.Layer-by-layer spin-coating with intermediate annealing achieved the target LaNiO3 electrode thickness.Mn-doped BiFeO3 solutions(0,1%,3%,5%Mn-doping)were prepared by dissolving bismuth nitrate(10%excess),iron nitrate,and manganese acetate in ethylene glycol monomethyl ether(0.4 mol/L concentration),adding citric acid(1:1 molar ratio to metal ions)as a chelating agent,magnetically stirring for 4 h at 25℃,and aging for 48 h.These sols were spin-coated onto LaNiO3/mica substrates,followed by 10 iterative cycles of thermal treatment:drying at 200℃(5 min),pyrolysis at 400℃(5 min),and crystallization at 550℃(5 min)per layer to attain the final film thickness. Results and discussion The LaNiO3 seed layer promotes a dominant(001)texture in BiFe1-xMnxO3(0%,1%,3%,5%Mn)thin films.However,increasing Mn dopant concentration induces compressive stress relaxation,significantly degrading the film texture from 92.3%to 56.7%.Undoped and 0.01%Mn-doped films exhibit pronounced out-of-plane self-polarization,yielding piezoelectric coefficients d33,d=48.6 pC/N and 47.4 pC/N.Internal bias in PFM voltage-phase/amplitude curves and unipolar conduction in I-V characteristics unequivocally confirm a built-in electric field.This field weakens at higher Mn concentrations(x=0.03 and 0.05),concurrently diminishing self-polarization—A causal relationship demonstrating that self-polarization originates from this internal field.Although increased Mn doping reduces self-polarization,it,however,significantly improves electrical performance:leakage current decreases by 78%at x=0.05 compared to undoped films.Therefore,optimal Mn doping(x=0.01)synergistically preserves self-polarization while enhancing electrical performance.As flexible films,BiFe1-xMnxO3 demonstrates exceptional bending stability and mechanical fatigue resistance.P-E hysteresis loops remain invariant under compressive/tensile stresses compared to undeformed states.After 5000 bending cycles at tensile strain(r=10 mm),ferroelectric properties and piezoelectric coefficient d33,d degrade by<10%,confirming outstanding operational durability. Conclusions This work demonstrates that LaNiO3 seed layers deposited on mica substrates induce a dominant(001)texture in BiFeO3-based thin films.Undoped and 0.01%Mn-doped compositions exhibit significant self-polarization driven by a built-in electric field,while increased Mn doping reduces texture degree from 92.3%to 56.7%and weakens self-polarization.The latter is evidenced by the decrease of piezoelectric coefficient,d33,d,from 48.6 pC/N to 14.6 pC/N.Crucially,despite diminishing self-polarization,Mn doping substantially enhances electrical properties(78%leakage reduction at x=0.05).All films endow exceptional mechanical resilience:after 5,000 bending cycles(r=10 mm),d33,d degrades<10%,with P-E hysteresis loops remaining unaffected.By synergistically integrating texture engineering and doping optimization,we achieve self-poling with a d33,d≈50 pC/N,establishing a novel technological pathway for lead-free flexible ferroelectric devices.关键词
铁酸铋薄膜/自极化行为/溶胶凝胶法/柔性Key words
bismuth ferrite thin film/self-polarization behavior/sol-gel method/flexibility分类
通用工业技术引用本文复制引用
周智强,黄硕,戴乐,刘丽莎..织构诱发柔性BiFeO3薄膜自极化性能调控[J].硅酸盐学报,2025,53(9):2441-2451,11.基金项目
中国科协青年人才托举工程(2021-2023QNRC001). （2021-2023QNRC001）
