Open AccessEffect of manganese doping on ferroelectric and piezoelectric properties of KNbO<sub>3</sub> and (K<sub>0.5</sub>Na<sub>0.5</sub>)NbO<sub>3</sub> lead-free ceramics
Author(s) -
Ze Xu,
L. K. V. Lou,
Chunlin Zhao,
Haocheng Tang,
Yixuan Liu,
Zhao Li,
Xiao-Mei Qi,
BoPing Zhang,
JingFeng Li,
Wen Gong,
Ke Wang
Publication year - 2020
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.69.20200277
Subject(s) - natural bond orbital , potassium niobate , materials science , doping , manganese , ferroelectricity , mineralogy , analytical chemistry (journal) , crystallography , chemistry , dielectric , metallurgy , optoelectronics , density functional theory , computational chemistry , chromatography
Potassium sodium niobate ((K 0.5 Na 0.5 )NbO 3 )-based lead-free piezoelectric ceramics are excellent ferroelectric materials and have been demonstrated to have many practical applications. Recent studies have revealed that chemical doping plays a crucial role in optimizing the electromechanical coupling properties of (K 0.5 Na 0.5 )NbO 3 -based piezoelectric ceramics. In this paper, MnO 2 is doped into potassium niobate (KNbO 3 ) and (K 0.5 Na 0.5 )NbO 3 piezoelectric ceramics prepared by the conventional solid-state reaction method. The influences of doped Mn cation on KNbO 3 and (K 0.5 Na 0.5 )NbO 3 piezoelectric ceramics including microstructure and macroscopic electrical properties are systematically investigated. The doping effects of Mn cation on the KNbO 3 and (K 0.5 Na 0.5 )NbO 3 piezoelectric ceramics are significantly different from each other. For the Mn-doped KNbO 3 piezoelectric ceramics, the sizes of ferroelectric domains are reduced. Meanwhile, the diffused orthorhombic-tetragonal phase transition is observed, which is accompanied by reducing dielectric loss and Curie temperature, and broadening vibration peaks in Raman spectrum. It is known that the oxygen vacancy can be formed to compensate for the charges created by the acceptor doping of Mn into the B site of perovskite, and thus forming a defect dipole with the acceptor center. From the ferroelectric measurement, a double hysteresis loop ( P - E curve) and a recoverable electric-field-induced strain due to the formation of defect dipole are observed. On the contrary, for the Mn-doped (K 0.5 Na 0.5 )NbO 3 piezoelectric ceramics, the sizes of ferroelectric domains are not reduced. Meanwhile, the Curie temperature and vibration peaks in Raman spectrum are not changed. A rectangular hysteresis loop ( P - E curve) and an unrecoverable electric-field-induced strain are observed in the ferroelectric measurement. The difference between these systems might originate from the greater ionic disorder and lattice distortion in (K 0.5 Na 0.5 )NbO 3 piezoelectric ceramics. The difference in ionic radius between Na + and K + can affect the migration and distribution of oxygen vacancies, which makes it difficult to form stable defect dipoles in the Mn-doped (K 0.5 Na 0.5 )NbO 3 piezoelectric ceramics. The results will serve as an important reference for preparing high-performance (K 0.5 Na 0.5 )NbO 3 -based piezoelectric ceramics via chemical doping.