Abstract

Lead‐based piezoceramics are the dominant materials used in electronic devices, despite the known toxicity of lead. Developing safer piezoelectric materials has inspired the pursuit of lead‐free piezoceramics, however some challenges remain in accessing these materials reproducibly. Here we demonstrate a simple and robust method for synthesis of the lead‐free piezoceramic material, potassium sodium niobate (KxNa1‐xNbO3, KNN) via an aqueous route. Stochiometric KNN (K0.5Na0.5NbO3) was prepared, by combining alkali‐nitrate salts (NaNO3 and KNO3) with the hexaniobate ([HxNb6O19]8‐x, Nb6) species in water, followed by heating at elevated temperatures for at least one hour. Ex situ heating of the amorphous alkali‐Nb6 precursor reveals stoichiometric control and phase uniformity are possible in making KNN, versus a solid‐state route. In situ heating in a transmission electron microscope (TEM), with selected area electron diffraction (SAED), facilitates monitoring the real‐time transformation of the amorphous alkali‐Nb6 precursor, to yield monoclinic KNN, in agreement with ex situ results. Therefore, an aqueous route via hexaniobate is an attractive alternative approach for developing lead‐free piezoceramic materials.