Open AccessMgNb 2 O 6 Modified K 0.5 Na 0.5 NbO 3 Eco‐Piezoceramics: Scalable Processing, Structural Distortion and Complex Impedance at Resonance
Author(s) -
Iacomini Antonio,
Garroni Sebastiano,
Senes Nina,
Mulas Gabriele,
Enzo Stefano,
Poddighe Matteo,
García Álvaro,
Bartolomé José F.,
Pardo Lorena
Publication year - 2021
Publication title -
chemistryopen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 29
ISSN - 2191-1363
DOI - 10.1002/open.202100089
Subject(s) - natural bond orbital , materials science , analytical chemistry (journal) , orthorhombic crystal system , microstructure , dielectric , ceramic , piezoelectricity , scanning electron microscope , mineralogy , phase (matter) , crystallography , crystal structure , chemistry , density functional theory , composite material , optoelectronics , computational chemistry , organic chemistry , chromatography
In this work, piezoceramics of the lead‐free composition K 0.5 Na 0.5 NbO 3 with an increasing amount of MgNb 2 O 6 (0, 0.5, 1, 2 wt.%) were prepared through conventional solid‐state synthesis and sintered in air atmosphere at 1100 °C. The effect of magnesium niobate addition on structure, microstructure and piezoelectric properties was evaluated. The ceramics maintain the orthorhombic Amm2 phase for all compositions, while an orthorhombic Pbcm secondary phase was found for increasing the concentration of MgNb 2 O 6 . Our results show that densification of these ceramics can be significantly improved up to 94.9 % of theoretical density by adding a small amount of magnesium‐based oxide (1 wt.%). Scanning electron microscopy morphology of the 1 wt.% system reveals a well‐packed structure with homogeneous grain size of ∼2.72 μm. Dielectric and piezoelectric properties become optimal for 0.5–1.0 wt.% of MgNb 2 O 6 that shows, with respect to the unmodified composition, either higher piezoelectric coefficients, lower anisotropy and relatively low piezoelectric losses (d 33 =97 pC N −1 ; d 31 =−36.99 pC N −1 and g 31 =−14.04×10 −3 mV N −1 ; Q p (d 31 )=76 and Q p (g 31 )=69) or enhanced electromechanical coupling factors (k p =29.06 % and k 31 =17.25 %).