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Composition and temperature dependence of structure and piezoelectricity in (1−x)(K 1−y Na y )NbO 3 ‐x(Bi 1/2 Na 1/2 )ZrO 3 lead‐free ceramics
Author(s) -
Wang Dawei,
Hussain Fayaz,
Khesro Amir,
Feteira Antonio,
Tian Ye,
Zhao Quanliang,
Reaney Ian M.
Publication year - 2017
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.14589
Subject(s) - phase boundary , analytical chemistry (journal) , raman spectroscopy , tetragonal crystal system , natural bond orbital , materials science , dielectric , x ray crystallography , chemical composition , temperature coefficient , phase (matter) , crystallography , mineralogy , chemistry , diffraction , crystal structure , density functional theory , optics , chromatography , composite material , physics , computational chemistry , optoelectronics , organic chemistry
Lead‐free piezoceramics with the composition (1−x)(K 1− y N a y )NbO 3 ‐x(Bi 1/2 Na 1/2 )ZrO 3 ( KN yN‐ xBNZ ) were prepared using a conventional solid‐state route. X‐ray diffraction, Raman spectroscopy, and dielectric measurements as a function of temperature indicated the coexistence of rhombohedral (R) and tetragonal (T) phase, typical of a morphotropic phase boundary ( MPB ) as the BNZ concentration increased and by adjusting the K/Na ratio. High remnant polarization ( P r =24 μC/cm 2 ), piezoelectric coefficient ( d 33 =320 pC /N), effective piezocoefficient ({d_{33}^*}=420 pm/V), coupling coefficient ( k p =48%), and high strain ( S =0.168%) were obtained at room temperature, but significant deterioration of P r , {d_{33}^*}, and k p were observed by increasing from room temperature to 160°C (17.5 μC/cm 2 , 338 pm/V, and 32%, respectively) associated with a transition to a purely T phase. Despite these compositions showing promise for room‐temperature applications, the deterioration in properties as a function of increasing temperature poses challenges for device design and remains to be resolved.