The phase structure and electric properties of low-temperature sintered (K, Na)NbO3-based piezoceramics modified by CuO

Further Enhancing Piezoelectric Properties by Adding MnO2 in AgSbO3‐Modified (Li,K,Na)(Nb,Ta)O3 Lead‐Free Piezoceramics

“…11 However, the normal strain d 33 * plays an important role in the actuator applications. 13,16 The converse piezoelectric constant d 33 * at 1 kV/mm and the representative unipolar electric field-induced strain curves at 1 and 2 kV/mm and of LKNNT-0.0525AS-x wt% MnO 2 piezoceramics with 0 ≤ x ≤ 1.5 are demonstrated in Fig. 9.…”

“…2,3,10,11 The piezoelectricity of KNN-based ceramics lacks temperature stability mainly because its enhancement is realized through polymorphic phase transition (PPT), which is adjusted nearly room temperature whereby two phases coexist. 2,3,7,[12][13][14][15][16][17][18][19] Certainly, the possible approach to enhance the temperature stability is shifting the PPT boundary well below ambient temperature, but it will lead to a sacrifice of piezoelectric performance. 20 Although fabricating textured samples was adopted as a solution to the dilemma, this approach is too complex for mass production.…”

Multi-phase structure and electrical properties of Bi0.5Li0.5ZrO3 doping K0.48Na0.56NbO3 lead-free piezoelectric ceramics

“…It is well known that the pure KNN ceramics prepared by solid-state sintering exhibit a low piezoelectric constant 33 of only 80-125 pC/N [9][10][11]. Therefore, it is necessary to enhance the piezoelectric properties of KNN ceramics.…”

“…Since alkali K and Na ions are easy to volatilize when the sintering temperature is above 1000 ℃, adding excessive alkali Na could be in favor of reducing the sintering temperature of KNN-based ceramics, replenishing the decreased amount of alkali Na and K volatilized [13,28,29] and improving the piezoelectric properties. Zhang et al [10] reported that high density (relative density over 95%) and piezoelectric constant 33 = 279 pC/N were achieved by adding excessive Na in the Li 0.058 (Na 0.52+x K 0.48 ) 0.942 NbO 3 ceramic as x = 0.015 sintering at a lower temperature 1000 ℃. Thus, in the present investigation, the (1-x)K 0.48 Na 0.56 NbO 3 -xBi 0.5 Li 0.5 ZrO 3 (KNN-xBLZ, x = 0-0.06) system with excessive Na + content was designed to obtain both high C and piezoelectric properties.…”

“…Our previous work [12,13] indicated that excessive Na 2 O which was to compensate the volatilization of Na + could effectively improve the piezoelectric properties by 10%-40% in KNN ceramics. Furthermore, 33 of KNN ceramics was increased by 188-324 pC/N as the replacement of K + and Na + with Li + in (K,Na,Li)NbO 3 system because of the appearance of polymorphic phase boundary (PPB) phase [14]. Thus, adding Li + to KNN ceramics can increase the Curie temperature ( ), decrease the phase transition temperature of orthorhombic (O) and tetragonal (T) ( ) to room temperature, slightly affect the phase transition temperature of rhombohedral (R) and O ( ), decline the sintering temperature, and improve the density of KNN materials, besides improving the piezoelectric properties.…”