Optimized processing conditions for Pt/TiO2/SiO2/Si templating electrodes were investigated. These electrodes are used to obtain [111] textured thin film lead zirconate titanate (Pb[ZrxTi1-x ]O3 0 ≤ x ≤ 1) (PZT). Titanium deposited by dc magnetron sputtering yields [0001] texture on a thermally oxidized Si wafer. It was found that by optimizing deposition time, pressure, power, and the chamber pre-conditioning, the Ti texture could be maximized while maintaining low surface roughness. When oxidized, titanium yields [100]-oriented rutile. This seed layer has as low as a 4.6% lattice mismatch with [111] Pt; thus, it is possible to achieve strongly oriented [111] Pt. The quality of the orientation and surface roughness of the TiO2 and the Ti directly affect the achievable Pt texture and surface morphology. A transition between optimal crystallographic texture and the smoothest templating surface occurs at approximately 30 nm of original Ti thickness (45 nm TiO2). This corresponds to 0.5 nm (2 nm for TiO2) rms roughness as determined by atomic force microscopy and a full-width at half-maximum (FWHM) of the rocking curve 0002 (200) peak of 5.5/spl degrees/ (3.1/spl degrees/ for TiO2). A Pb[Zr0.52Ti 0.48]O3 layer was deposited and shown to template from the textured Pt electrode, with a maximum [111] Lotgering factor of 87% and a minimum 111 FWHM of 2.4/spl degrees/ at approximately 30 nm of original Ti.
A pulsed laser deposition system with in situ laser annealing was utilized to grow Pb(Zr0.52Ti0.48)O3 thin films on a laser crystallized Pb(Zr0.20Ti0.80)O3 seed layer, at a temperature of ∼370 °C. Polycrystalline 1.1 μm thick films exhibited columnar grains with small grain sizes (∼30 nm). The films showed well-saturated hysteresis loops (with ∼25 μC/cm2 remanent polarization, ∼50 kV/cm coercive field) and exhibited loss tangents <2.5% with a permittivity of ∼730. Film orientation could be controlled via the substrate choice; {111} Pb(Zr0.52Ti0.48)O3 films were grown on oriented (111) Pb(Zr0.30Ti0.70)O3 sol-gel seed layers, while {001} films were prepared on (100) SrTiO3 single crystals.
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.
The cover highlights the relationship between structure, properties, and application through images from three papers in the Ferroelectric Special Issue.Representing structure, the top-left image is a schematic representation of BiFeO 3 , showing FeO 6 octahedra. For further reading, see the paper "Composition-Driven Structural Phase Transitions in Rare-Earth-Doped BiFeO 3 Ceramics: A Review" by Donna Arnold, on page 62 of this issue.Representing properties, the right image shows atomic force micrographs of Ti deposited to achieve an enhanced textured PZT film. For further reading, see the paper "Control of Crystallographic Texture and Surface Morphology of Pt/TiO 2 Templates for Enhanced PZT Thin Film Texture" by Austin J. Fox, Bill Drawl, Glen R. Fox, Brady J. Gibbons, and Susan Trolier-McKinstry, on page 56 of this issue.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.