Synthesis and characterization of two-dimensional lead-free (K, Na)NbO3 micro/nano piezoelectric structures

Abstract

Two-dimensional (2D) lead-free (K, Na)NbO 3 (KNN) micro/nano structures with controllable K/Na ratio were successfully fabricated via a two-step molten salt synthesis (MSS). In this work, the reaction factors, including the proportion of molten salts, the types of carbonates, the sintering temperature, and the sintering time, were discussed in detail and the optimized condition was identified. The microstructure of KNN was confirmed by confocal Raman spectroscopy, while piezoresponse force microscopy (PFM) was applied to measure three-dimensional (3D) morphology and piezoelectric properties of KNN particles. The as-synthesized KNN platelets apparently possess anisotropic morphology and uniform structure, the size of which reaches 5-20 µm in length/width and 0.5-1 µm in thickness. It should be noted that the K/Na ratios of the KNN crystals are basically consistent while the proportion of salts changes within a certain range. The enrichment of Na element in the products is also observed, which owes to the smaller ionic radius of Na + comparing to that of K +. This result provides a reference for the further preparation of textured ceramics and flexible piezoelectric generators.

Ultrafast synthesis and densification of ZrO2 doped KNN ceramics by reactive flash sintering

“…Potassium sodium niobate ((K,Na)NbO 3 , KNN)-based ceramics are regarded as one of the most promising lead-free piezoelectric ceramics owing to their excellent piezoelectric response and high Curie temperature. [23][24][25][26] To achieve the desired properties of the KNN-based ceramics, doping is a mostly used way to tune their phase compositions, microstructures, and electrical performances. [27][28][29] For example, ZrO 2 is recently served as a dopant into KNN ceramics to suppress the grain growth and manipulate the piezoelectric properties.…”

“…Potassium sodium niobate ((K,Na)NbO 3 , KNN)‐based ceramics are regarded as one of the most promising lead‐free piezoelectric ceramics owing to their excellent piezoelectric response and high Curie temperature 23–26 27–29 .…”

Toward Eco‐Friendly Lead‐Free Low‐Dimensional Perovskites

“…[92] The light-emitting properties can be flexibly tuned by the management of the energy-level alignment between the organic and organic components. When the exciton level of the inorganic layer is located above the singlet level of organic spacers, the luminescence of 2D perovskites is mainly dominated by the OC [108,109] PV [110,111] MG [112] FE [113,114] CO [115] PZE [116] 1D -LM [17,117] FE [118,119] FM [120] 0D [121,122] PV [123] FE [124] a) E g (bandgap), e (electronic effective mass), m h (hole effective mass), E b (exciton binding energy), optoelectronic (OC), photovoltaic (PV), magnetic (MG), ferroelectric (FE), chiral optics (CO), piezoelectricity (PZE), luminescence (LM), ferromagnetism (FM). The E b is assessed by using a simple Wannier exciton model.…”

Magnetic Field‐Enhanced Electrocatalytic Oxygen Evolution on a Mixed‐Valent Cobalt‐Modulated LaCoO3 Catalyst

“…[28,29] Lanthanum cobaltate (LaCoO 3 , LCO) is a typical and representative perovskite cobalt oxide with the general formulation of ABO 3 , which has received the most attention in electrocatalytic OER due to its simple preparation process, distinctive electrical, structural, magnetic and catalytic characteristics. [30][31][32][33] However, the electrocatalytic activity of LCO is severely restricted, which is the result of the dissatisfactory adsorption of oxygen-containing intermediate due to inappropriate spin configuration of Co ions. [34] Previous work demonstrated that more than one A-site and/or B-site cation can be admitted into the perovskite structure since it possessed the admirable tolerance of lattice heterogeneity and mismatch between different metal (A/B)À O bond lengths.…”