Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/79858
Title: Thickness-dependent structural and electromechanical properties of (Na0.85K0.15)(0.5)Bi0.5TiO3 multilayer thin film-based heterostructures
Authors: Wu, YY 
Or, SW 
Keywords: Heterostructures
Interfacial passive layer
Lead-free piezoelectric
Multilayer thin films
Thickness-dependent properties
Issue Date: 2018
Publisher: Elsevier
Source: Materials and design, 5 July 2018, v. 149, p. 153-164 How to cite?
Journal: Materials and design 
Abstract: (Na0.85K0.15)(0.5)Bi0.5TiO3 (NKBT) multilayer thin films with different thicknesses of 100-700 nm, corresponding to 2-14 layers with each layer of similar to 50 nm thickness, are synthesized on Pt(111)/Ti/SiO2/Si substrates to form Pt/NKBT/Pt/Ti/SiO2/Si heterostructures using different spin-coating and annealing conditions in a modified aqueous sol-gel process. The multilayer thin films spin-coated by two steps (step 1/2) at 600/4000 rpm for 6/30 s and annealed at 700 degrees C for 5 min with a heating rate of 30 degrees C/s show a dense, uniform, and continuous morphology as well as a pure perovskite structure with a rhombohedral-tetragonal phase transition at similar to 140 degrees C and no preferential orientation in the heterostructures. Their structural and electromechanical properties exhibit consistent improvement trends with increasing thickness from 100 to 550 nm(i.e., 2-11 layers). The 550 nm-thick, 11-layer films demonstrate the best ferroelectric, dielectric, piezoelectric, and electric performance in terms of the highest remnant polarization, saturation polarization, dielectric constant, and effective piezoelectric constant of 18.3 mu C/cm(2), 53.6 mu C/cm(2), 463, and 64 pm/V, as well as the lowest coercive field, dielectric loss tangent, and leakage current density of 116 kV/cm, 0.057, and 27 mu A/cm(2), respectively. The observed thickness-dependent improvement is explained by an interfacial passive layer effect where the motion of both 180 degrees and non-180 degrees domain walls is enhanced in the thicker multilayer thin films by weakening the influence of domain pinning in the interfacial passive layers between the multilayer thin films and the substrates.
URI: http://hdl.handle.net/10397/79858
ISSN: 0264-1275
EISSN: 1873-4197
DOI: 10.1016/j.matdes.2018.04.012
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