Large Piezoresponse and Ferroelectric Properties of (Bi_0.5Na_0.5)TiO₃–(Bi_0.5K_0.5)TiO₃–Bi(Mg_0.5Ti_0.5)O₃ Thin Films Prepared by Chemical Solution Deposition

Abstract

Bulk ceramic 72.5 mol%(Bi0.5Na0.5)TiO3–22.5 mol%(Bi0.5K0.5)TiO3–5 mol%Bi(Mg0.5Ti0.5)O3 (BNT–BKT–BMgT) has previously been reported to show a large high‐field piezoelectric coefficient (d33* = 570 pm/V). In this work, the same composition was synthesized in thin film embodiments on platinized silicon substrates via chemical solution deposition. Overdoping of volatile cations in the precursor solutions was necessary to achieve phase‐pure perovskite. An annealing temperature of 700°C resulted in good ferroelectric properties (Pmax = 52 μC/cm2 and Pr = 12 μC/cm2). Quantitative compositional analysis of films annealed at 650°C and 700°C indicated that near ideal atomic ratios were achieved. Compositional fluctuations observed through the film thickness were in good agreement with the existence of voids formed between successive spin‐cast layers, as observed with electron microscopy. Bipolar and unipolar strain measurements were performed via double laser beam interferometry and a high effective piezoelectric coefficient (d33,f) of approximately 75 pm/V was obtained.

High Piezoelectric Performance and Phase Transition in Stressed Lead‐Free (1 – x)(K, Na)(Sb, Nb)O3‐x(Bi, Na, K)ZrO3 Thin Films

“…It should be highlighted that here all piezoelectric properties were measured and evaluated over macroscale, in contrast to nanoscale characterization such as with piezoresponse force microscope where the errors due to possible substrate bending movement and inhomogeneous local effect cannot be excluded. In comparison with the reported macroscale properties of KNN‐based and other lead‐free piezoelectric thin films (Figure b), the KNSN‐BNKZ0.05 film from this work exhibits the largest d 33 and g 33 values . The effective d 33 and g 33 from our KNSN‐BNKZ0.05 film are even higher than typical PZT thin films ( d 33 : 102–137 pm V −1 and g 33 : ≈ 25.7 mm V N −1 over macroscale).…”

Outstanding Piezoelectric Performance in Lead‐Free 0.95(K,Na)(Sb,Nb)O3‐0.05(Bi,Na,K)ZrO3 Thick Films with Oriented Nanophase Coexistence

“…In the past few decades, lead zirconate titanate (PZT) thin films with excellent piezoelectric properties have dominated the commercial market of piezoelectric thin film devices. However, the high content of toxic lead composition in PZT raises environmental and human health concerns, thus increasing efforts are made to develop high performance lead‐free piezoelectric thin films as replacements . Among lead‐free piezoelectric ceramics, potassium sodium niobate, (K, Na)NbO 3 (KNN), is one of the most promising candidates with competitive piezoelectric properties over a broad temperature range, as obtained in KNN‐based bulk ceramics by constructing phase coexistence with complex chemical compositions .…”

High electromechanical strain and enhanced temperature characteristics in lead-free (Na,Bi)TiO3–BaTiO3 thin films on Si substrates

“…However, the NBT–BT films on Si are generally in tensile stress arising from lower thermal expansion coefficient, α , of NBT–BT ( α  = 11 ppm/K) 21 comparing that ( α  = 2.6–4.3 ppm/K) of Si, which causes a distortion of the crystal lattice toward the in-plane ( a -axis) direction i.e. a -axis preferential orientation and thereby the piezoelectric properties become low 23–25 .…”