Enhanced Piezoelectric Response in Orientation-Controlled BiFe1–xGaxO3 Thin Films with Polarization Rotation

AbstractTraditional strategies for improving piezoelectric properties have focused on phase boundary engineering through complex chemical alloying and phase control. Although they have been successfully employed in bulk materials, they have not been effective in thin films due to the severe deterioration in epitaxy, which is critical to film properties. Contending with the opposing effects of alloying and epitaxy in thin films has been a long-standing issue. Herein we demonstrate a new strategy in alkali niobate epitaxial films, utilizing alkali vacancies without alloying to form nanopillars enclosed with out-of-phase boundaries that can give rise to a giant electromechanical response. Both atomically resolved polarization mapping and phase field simulations show that the boundaries are strained and charged, manifesting as head-head and tail-tail polarization bound charges. Such charged boundaries produce a giant local depolarization field, which facilitates a steady polarization rotation between the matrix and nanopillars. The local elastic strain and charge manipulation at out-of-phase boundaries, demonstrated here, can be used as an effective pathway to obtain large electromechanical response with good temperature stability in similar perovskite oxides.

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Nanostructure Analysis of Sol-gel PZT Thin Films Derived from Different Chemical Routes

Microscopy and Microanalysis ◽

10.1017/s1431927609990729 ◽

2009 ◽

Vol 15 (S3) ◽

pp. 53-54

Author(s):

Aiying Wu ◽

P. M. Vilarinho

Keyword(s):

Thin Films ◽

Data Storage ◽

Chemical Reactivity ◽

Sol Gel ◽

Random Access ◽

Lead Zirconate ◽

Piezoelectric Response ◽

Metal Alkoxides ◽

Pzt Thin Films ◽

Wide Range

AbstractLead zirconate - lead titanate (PZT) materials are commercially important piezoelectric and ferroelectrics in a wide range of applications, such as data storage (dynamic access and ferroelectric random access memories) and sensing and actuating devices. PZT with the morphotropic phase boundary composition offers the highest piezoelectric response and at the present there are no fullydeveloped alternative materials to PZT. The importance of PZT associated with the continuous requirements of device miniaturization, imposes the development of high quality PZT thin films with optimized properties. Concomitantly due to the dependence of the final properties of thin films on the details of the microstructure a thoroughly analysis at the local scale of their microstructure is necessary. Sol-gel method, is one of the Chemical Solution Deposition techniques used to prepare oxide thin films, such as PZT. Starting from a solution, a solid network is progressively formed via inorganic polymerisation reactions. Most metal alkoxides used for sol-gel synthesis are highly reactive towards hydrolysis and condensation. Therefore their chemical reactivity has to be tailored via the chemical modification (or complexation) of metal alkoxides to avoid uncontrolled reactions and precipitation. For PZT sol gel thin film preparation, two chemical routes are frequently used depending on the nature of the molecular precursor, namely methotoxyethanol (MOE) route and diol-route.

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Mixing nanostructured Ni/piezoPVDF composite thin films with e-beam irradiation: A beneficial synergy to piezoelectric response

Materials Today Communications ◽

10.1016/j.mtcomm.2021.102528 ◽

2021 ◽

pp. 102528

Author(s):

Natalia Potrzebowska ◽

Olivier Cavani ◽

Ozlem Oral ◽

Olivier Doaré ◽

Giuseppe Melilli ◽

...

Keyword(s):

Thin Films ◽

Piezoelectric Response ◽

Beam Irradiation ◽

Composite Thin Films

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Impact of process conditions on chemical solution deposited BNKT thin film electromechanical properties

SN Applied Sciences ◽

10.1007/s42452-021-04692-4 ◽

2021 ◽

Vol 3 (10) ◽

Author(s):

Kyle M. Grove ◽

Austin Fox ◽

David P. Cann ◽

Song Won Ko ◽

Peter Mardilovich ◽

...

Keyword(s):

Thin Film ◽

Thin Films ◽

Dielectric Constant ◽

Dielectric Loss ◽

Pyrolysis Temperature ◽

Piezoelectric Response ◽

Excess Properties ◽

Process Conditions ◽

Chemical Solution ◽

Ramp Rate

Abstract Phase pure perovskite (1-x)Bi1/2Na1/2TiO3 – xBi1/2K1/2TiO3 (BNKT) thin films were successfully prepared via an inverse mixing order chemical solution deposition method and the impact of process conditions on film properties were observed. Process conditions evaluated included crystallization temperature and time, ramp rate, pyrolysis temperature, and cation excess. Properties measured included crystal structure, dielectric constant, dielectric loss, piezoelectric response, and ferroelectric response. A few notable trends were observed. A subtle impact on piezoelectric response was observed in films prepared using different ramp rates: 100 C per second films (d33,f = 60 ± 5 pm/V at 1 kHz), 75 °C per second films (d33,f = 55 ± 5 pm/V) and 150 C per second films (d33,f = 50 ± 5 pm/V). Films prepared using a 75 °C per second ramp rate displayed slightly higher dielectric loss (tan δ = 0.09 at 1 kHz) than films prepared using a 100 °C per second ramp rate (tan δ = 0.07 at 1 kHz) or 150 °C per second ramp rate (tan δ = 0.05 at 1 kHz). Pyrolysis temperatures greater than 350 °C are necessary to burn off organics and maximize film dielectric constant. Dielectric constant increased from 450 ± 50 at 1 kHz to 600 ± 50 at 1 kHz by increasing pyrolysis temperature from 300 to 400 °C. Excess cation amounts (for compositional control) were also evaluated and it was found films with higher amounts of Na and K excess compared to bismuth excess displayed an increase in d33,f of about 10 pm/V compared to films prepared with equivalent Bi and Na and K excess amounts. Article highlights Impact of processing conditions on inverse mixing order chemical solution deposited bismuth based thin films. Dielectric, piezoelectric, and ferroelectric properties of thin film bismuth sodium titanate-bismuth potassium titanate thin films. Developing lead-free piezoelectric actuator materials.

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