Mechanism of densification in low-temperature FLASH sintered lead free potassium sodium niobate (KNN) piezoelectrics
authors Serrazina, R; Dean, JS; Reaney, IM; Pereira, L; Vilarinho, PM; Senos, AMOR
nationality International
journal JOURNAL OF MATERIALS CHEMISTRY C
keywords FREE PIEZOCERAMICS; GRAIN-GROWTH; MICROSTRUCTURE; MODEL; ZNO
abstract Lead-free potassium sodium niobate (K0.5Na0.5NbO3, KNN) piezoelectric ceramics have been densified at temperatures lower than 300 degrees C using atmosphere-water assisted FLASH sintering. Transmission electron microscopy (TEM) studies revealed amorphous phase at grain boundaries that resulted from surface melting of the cuboid particles in the presence of segregated impurities. We propose that preferential surface melting of the primary particles is induced in conductive channels of open pores in which water is adsorbed. This creates a network of pathways for the electric current. The resulting liquid phase induces fast densification through sliding of grain boundaries and viscous flow of the liquid driven by minimisation of surface energy. Finite Element Modelling (FEM) revealed that current density and Joule heating were also influenced by the geometry of contact between the cuboid KNN particles with vertex to vertex inducing the maximum current density and consequently creating the greatest volume of amorphous phase in adjacent pores. The lowest current density was predicted for face to face contacts, resulting in only a thin amorphous layer between grains.
publisher ROYAL SOC CHEMISTRY
issn 2050-7526
isbn 2050-7534
year published 2019
volume 7
issue 45
beginning page 14334
ending page 14341
digital object identifier (doi) 10.1039/c9tc03117k
web of science category Materials Science, Multidisciplinary; Physics, Applied
subject category Materials Science; Physics
unique article identifier WOS:000503215800030
  ciceco authors
  impact metrics
journal analysis (jcr 2019):
journal impact factor 7.059
5 year journal impact factor 6.404
category normalized journal impact factor percentile 85.94
dimensions (citation analysis):
altmetrics (social interaction):



 


Apoio

1suponsers_list_ciceco.jpg