Effects of nano-sized BCZT on structure and electrical properties of KNN-based lead-free piezoceramics

Structure, dielectric, and piezoelectric properties of K0.5Na0.5NbO3-based lead-free ceramics

“…10,13,23,34,62,[64][65][66] In addition to changes in the crystal symmetry, microstructure induced domain reconguration can also improve the piezoelectric properties in optimally-doped piezoelectric materials. 12,17,18,24,26,30,31,64,67,68 In the present work, superior value of d 33 for the sample with x ¼ 0.02 can be attributed to the coexistent orthorhombic and rhombohedral phases at room temperature.…”

“…Similar behavior has been observed in other KNN-based systems and is usually taken as an indication of the polymorphic phase transition. 18,34,64,70 Unlike the classic morphotropic phase boundary (MPB) observed in PZT system, orthorhombic-rhombohedral phase coexistence in KNN-BZT shows strong temperature dependence as seen in the Fig. 8.…”

“…Earlier reports on the chemical modication of KNN-based ceramics have demonstrated the realization of a polymorphic phase boundary between orthorhombic and tetragonal phase around room temperature through the decreasing of the temperature of orthorhombic (O) to tetragonal (T) phase transitions. 18,[21][22][23][24][25][26]28,31,35,64,69 The R-T boundary between rhombohedral (R) and tetragonal (T) phases has also been reported in some systems where the orthorhombic phase in the KNN-based system is suppressed by the introduction of compositional disorder at the crystallographic equivalent sites in perovskite structure. [13][14][15]20,22,25,37 Compositions at R-T polymorphic phase boundary in the KNN-based systems attain much better piezoelectric properties than those having R-O or O-T phase boundary.…”

“…6,8,[10][11][12][13] Recently, a number of manpower and nancial resources are invested into the study of KNN-based piezoelectrics, and some signicant developments have been achieved. [9][10][11][12][13][14][15][16][17][18] KNN is a solid solution of ferroelectric compound KNbO 3 having space group Cm2m and antiferroelectric NaNbO 3 having space group Pbma with an orthorhombic perovskite structure at room temperature. 16 The composition near x ¼ 0.5 is of the great interest because of the superior ferroelectric and piezoelectric properties.…”

“…Several studies have been carried out to enhance the piezoelectric properties through the modication of the parent KNN compound by substitutions of some cations at Asite and/or B-site of KNN structure and microstructural engineering. 13,18,[20][21][22][23][24][25][26][27][28][29][30][31][32][33] For instance, KNN systems modied by LiTaO 3 and LiSbO 3 have improved the densication as well as enhanced the piezoelectric properties (d 33 ¼ 200-235 pC/N). 23,24,[34][35][36] Saito et al in 2004 reported a peak d 33 of $416 pC/N for textured KNNbased ceramics.…”