Microstructural origin for the piezoelectricity evolution in (K0.5Na0.5)NbO3-based lead-free ceramics

Abstract

Chemically modified (K0.5 Na 0.5)NbO3 compositions with finely tuned polymorphic phase boundaries (PPBs) have shown excellent piezoelectric properties. The evolution of the domain morphology and crystal structure under applied electric fields of a model material, 0.948(K0.5Na 0.5)NbO3-0.052LiSbO3, was directly visualized using in situ transmission electron microscopy. The in situ observations correlate extremely well with measurements of the electromechanical response on bulk samples. It is found that the origin of the excellentpiezoelectric performance in this lead-free composition is due to a tilted monoclinic phase that emerges from the PPB when poling fields greater than 14 kV/cm are applied. Disciplines Ceramic Materials | Materials Science and Engineering CommentsThe following article appeared in Journal of Applied Physics 114 (2013) Chemically modified (K 0.5 Na 0.5 )NbO 3 compositions with finely tuned polymorphic phase boundaries (PPBs) have shown excellent piezoelectric properties. The evolution of the domain morphology and crystal structure under applied electric fields of a model material, 0.948(K 0.5 Na 0.5 )NbO 3 -0.052LiSbO 3 , was directly visualized using in situ transmission electron microscopy. The in situ observations correlate extremely well with measurements of the electromechanical response on bulk samples. It is found that the origin of the excellent piezoelectric performance in this lead-free composition is due to a tilted monoclinic phase that emerges from the PPB when poling fields greater than 14 kV/cm are applied. V C 2013 AIP Publishing LLC.

Polarization alignment, phase transition, and piezoelectricity development in polycrystalline0.5Ba(Zr0.2Ti0.8)O3−Guo1, Voas2, Zhang3 et al. 2014Phys. Rev. BSelf Cite806360View full textAdd to dashboardCite

“…From a microstructural perspective, this composition in its virgin state contains nanoscale ferroelectric domains that are believed to facilitate polarization rotation during electrical poling and to enhance piezoelectricity [7]. Even though ferroelectric domains are known to dictate the dielectric, piezoelectric, and ferroelectric properties of polar oxides, their original morphologies and even crystal symmetries often times cannot survive the electrical poling process, as recently demonstrated in (K 0.5 Na 0.5 )NbO 3 -based [8] and (Bi 1/2 Na 1/2 )TiO 3 -based [9] * Corresponding author: xtan@iastate.edu solid solutions. The effective polarization alignment and extensive phase transition during poling are cited as primary factors contributing to their excellent piezoelectric performances [8,9].…”

“…For electric-field in situ TEM experiments, [8,9,[17][18][19]] disk specimens (3 mm in diameter) were prepared from as-sintered pellets through standard procedures, including grinding, cutting, dimpling, and ion milling. The dimpled disks were annealed at 200°C for 2 h to minimize the residual stresses before Ar-ion milling to the point of electron transparency.…”

“…Even though ferroelectric domains are known to dictate the dielectric, piezoelectric, and ferroelectric properties of polar oxides, their original morphologies and even crystal symmetries often times cannot survive the electrical poling process, as recently demonstrated in (K 0.5 Na 0.5 )NbO 3 -based [8] and (Bi 1/2 Na 1/2 )TiO 3 -based [9] * Corresponding author: xtan@iastate.edu solid solutions. The effective polarization alignment and extensive phase transition during poling are cited as primary factors contributing to their excellent piezoelectric performances [8,9]. Presumably, the hierarchical domain structure observed in unpoled 50BZT-50BCT ceramics does not survive electrical poling either, as both 180°and non-180°domain switching have been observed in poled BZT-BCT solid solutions [10][11][12][13].…”

Antiferroelectricity induced by electric field in NaNbO3-based lead-free ceramics

“…NaNbO 3 is a perovskite compound known for its complex structures and phase transitions. [13][14][15][16][17] Its solid solutions are of technological importance due to applications in lead-free piezoelectric devices [18][19][20] and high-temperature capacitors. 21 Although NaNbO 3 has been investigated for more than six decades, researchers are still debating whether it is antiferroelectric or ferroelectric at room temperature.…”

Unique single-domain state in a polycrystalline ferroelectric ceramic

“…The average grain size was determined to be 13.1 μm. For the electric field in situ transmission electron microscopy (TEM) experiments [13,[16][17][18][19] disk specimens (3 mm in diameter) were prepared from as-sintered pellets through standard procedures including grinding, cutting, dimpling, and ion milling. Prior to ion milling, the dimpled disks were annealed at 200°C for 2 h. In situ TEM experiments were carried out on a Phillips CM-30 microscope operated at 200 kV.…”