Enhanced piezoelectric properties in potassium-sodium niobate-based ternary ceramics

Abstract

1-x)K 0.5 Na 0.5 Nb 1-y Sb y O 3 -zSrZrO 3 -xBi 0.5 Na 0.5 HfO 3 (KNNS-SZ-BNH) lead-free ceramics were developed by the conventional solid-state reaction method. Effects of the additives (Bi 0.5 Na 0.5 HfO 3 , SrZrO 3 and Sb 5+ ) on their phase structure, microstructure, and electrical properties were investigated. The rhombohedral-orthorhombic-tetragonal (R-O-T) phase boundary can be established in the ceramics with 0.03≤x≤0.05, 0.04≤y≤0.06, and 0.01≤z≤0.025, and then their piezoelectric properties were improved. The ceramics with x=0.03, y=0.04 and z=0.01 possess the optimum piezoelectric properties (d 33 =470±5 pC/N, k p =0.51±0.02, andT C =244 o C). We believe that R-O-T multiphase coexistence is mainly responsible for the enhancement of piezoelectric properties.

Structural evolution of the R‐T phase boundary in KNN‐based ceramics

“…4 Here, both the R-T phase boundary and the ferroelectric domains were responsible for the enhancement of the piezoelectric properties. 28 Generally, both the dielectric and the ferroelectric properties play a role in the piezoelectric properties of ferroelectric materials, according to the relationship d 33 ∝ ae r P r , where a is the electrostrictive coefficient, ɛ r is the relative dielectric constant, and P r is the remanent polarization (P r is shown in Figure S8C-D). Furthermore, as discussed above, the ceramics possessing an R-T phase boundary exhibited an easy ferroelectric domain switching, which also increased the net piezoelectricity.…”

“…We obtained the optimal dielectric properties (e.g., ɛ r~2 240 and tan d~0.04) in the ceramics with x = 0.03 and y = 0.035 due to the R-T phase boundary. 28 Generally, both the dielectric and the ferroelectric properties play a role in the piezoelectric properties of ferroelectric materials, according to the relationship d 33 ∝ ae r P r , where a is the electrostrictive coefficient, ɛ r is the relative dielectric constant, and P r is the remanent polarization (P r is shown in Figure S8C-D). 29,30 The equation indicates that d 33 and ɛ r P r should display a similar variation.…”

Enhancing temperature stability in potassium-sodium niobate ceramics through phase boundary and composition design

“…As x further increased up to 0.035, TR-O and TO-T overlapped with each other, leading to the formation of an R-T phase boundary at TR-T [23,25,26]. The TR-T of the ceramics with x=0.035 and 0.04 was very near room temperature at 31±20 o C and 5±5 o C, respectively, suggesting the coexistence of the R and T phases at the room temperature [23,25,26]. For the ceramics with x=0.05, its TR-T of -4 o C was much lower than room temperature.…”

Effects of Bi0.5Na0.5HfO3 addition on the phase structure and piezoelectric properties of (K, Na)NbO3‐based ceramics

“…Very recently, some authors reported that the addition of (Bi 0.5 Na 0.5 )HfO 3 in KNN could lead to the formation of phase boundary as well as a remarkable enhancement of piezoelectric properties. Therefore, in this current work, we prepared the (1‐ x )(K 0.48 Na 0.48 Li 0.04 )Nb 0.95 Sb 0.05 O 3 ‐ x (Bi 0.5 Na 0.5 )HfO 3 [abbreviated as (1‐ x )KNLNS‐ x BNH] ceramics by a conventional solid‐state reaction route.…”

“…1,6,19 Hence in order to construct a phase boundary in KNN-based materials, one or both of the two phase-transition temperatures, known as T R-O and T O-T , respectively, should be adjusted to around room temperature through the addition of some other ions or ABO 3 -type compounds. 6 Very recently, some authors [20][21][22][23] reported that the addition of (Bi 0.5 Na 0.5 )HfO 3 in KNN could lead to the formation of phase boundary as well as a remarkable enhancement of piezoelectric properties. Therefore, in this current work, we prepared the (1-x)(K 0.48 Na 0.48 Li 0.04 ) Nb 0.95 Sb 0.05 O 3 -x(Bi 0.5 Na 0.5 )HfO 3 [abbreviated as (1-x) KNLNS-xBNH] ceramics by a conventional solid-state reaction route.…”