resumo
K0.5Na0.5NbO3 (KNN) is as a relevant lead-free piezoelectric material due to its piezoelectric performance and a high Curie temperature. Although high-sintering temperature is required for obtaining dense KNN ceramics, it favours alkalis volatilization with deleterious effects on the physical properties. Together with the need of more environmentally-friendly technologies for ceramic manufacturing, cold sintering (CSP), a low temperature sintering process, is a promising technique. CSP of incongruently dissolving materials (with different dissolution rates of constituents) is, however, a challenge. In this work, a systematic study of the interaction of KNN particles with water under different pH conditions and temperatures is used to elucidate the nature and mechanisms of KNN dissolution. The KNN dissolution follows the trend [K+] > [Na+] >> [Nb5+]. Differences are demonstrated between acidic, neutral, and alkaline conditions, with the latter exhibiting less incongruence. Acidic pH increases solubility of KNN and promotes the incongruence of dissolution. Oppositely, alkaline pH decreases solubility of KNN and prevents dissolution incongruence. The incongruence of KNN dissolution in aqueous media is quantified. These observations have implications for our understanding of powders dissolution and offer opportunities to control the stoichiometry of the powders, that might be the key for CSP of incongruently dissolving materials.
palavras-chave
FREE PIEZOELECTRIC CERAMICS; COLD; CYTOTOXICITY; SOLUBILITY; BEHAVIOR; RELEASE
categoria
Materials Science
autores
Wlódarkiewicz, A; Costa, ME; Vilarinho, PM
nossos autores
Maria Elisabete Jorge Vieira Costa
Colaborador
Paula Maria Lousada Silveirinha Vilarinho
Vice-DiretorProjectos
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
agradecimentos
This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020, financed by national funds through the FCT/MEC (PIDDAC).; Anna Wlodarkiewicz acknowledges FCT for financial support (SFRH/PD/BD/133784/2017). Our thanks to R.C. Pullar for helping to improve the English of this manuscript.