Enhanced Piezoelectric Properties of Potassium Niobate Single Crystals by Domain Engineering

Abstract

The engineered domain configuration was induced into potassium niobate (KNbO3) crystals, and the piezoelectric properties were investigated as a function of domain size. First, single-domain treatment was investigated, and a combination of chemical etching and 2-step electric poling treatment was effective. Using the single-domain crystals, all piezoelectric related constants were determined. On the basis of these piezoelectric constants, the d 31 and d 32 surfaces were calculated. The piezoelectric properties of [001] c oriented KNbO3 single-domain crystals were measured and were completely consistent with the calculated properties. Finally, the engineered domain configurations were induced into KNbO3 crystals by the control of the temperature and the electric-field along the [001] c direction. The piezoelectric properties of these KNbO3 crystals with the engineered domain configurations showed much higher values than those of the single-domain crystal. Moreover, the piezoelectric properties increased with decreasing the domain sizes of the engineered domain configuration.

Temperature dependence of the direct piezoelectric effect in relaxor-ferroelectric single crystals: Intrinsic and extrinsic contributions

“…Moreover, the intrinsic contribution, as measured along the non polar ͓001͔ C poling direction of each domain-engineered crystal, is also expected to increase as the first order ferroelectric-ferroelectric phase transition is approached. 25 There is significant evidence that the presence, rather than motion, of domain walls in domain-engineered barium titanate and potassium niobate leads to an increase piezoelectric response, [35][36][37][38][39] especially when the domain structure becomes very fine ͓Ͻ10 m ͑Ref. 38 and 39͔͒.…”

Domain size engineering in 0.5%MnO2-(K0.5Na0.5)NbO3 lead free piezoelectric crystals

“…[8][9][10][11][12] Domain size engineering is another important approach for obtaining enhanced piezoelectric properties in lead free piezoelectric single crystals. [13][14][15][16][17][18] The experimental results revealed that the enhanced piezoelectric coefficient was associated with high domain wall density, for example, the piezoelectric coefficient d 31 was found to increase from À98 pC/N to À230 pC/N with domain sizes of 40 lm and 5.5 lm in BaTiO 3 crystals, 15 while the piezoelectric coefficient d 33 was predicted to be greatly increased with nano-size domain configuration. 17 The theoretical simulation indicated that the piezoelectric coefficient was enhanced by reducing domain size, while an enhancement of piezoelectric coefficient in BaTiO 3 crystals with 90 twinned domain configuration was predicted using Ginzburg-LandauDevonshire model.…”

Domain engineering of the transverse piezoelectric coefficient in perovskite ferroelectrics

“…Following the rediscovery of their very high piezoelectric coefficients for rhombohedral or orthorhombic compositions oriented along the nonpolar ͓001͔ C ͑C: pseudocubic͒ direction, 1 much work has concentrated on the concept of domain engineering 2 not only in these materials [3][4][5][6][7] but in simpler perovskite crystals as well. [8][9][10] A good definition of "domain engineering" is that given by Bell: 2 A domain-engineered crystal is one which has been poled by the application of a sufficiently high field along one of the possible polar axes of the crystal other than the zerofield polar axis, creating a set of domains in which the polarizations are oriented such that their angles to the poling direction are minimized. In a perovskite material there are therefore three possible sets of poling directions ͗111͘ C , ͗101͘ C , and ͗001͘ C ͑if monoclinic phases are ignored͒.…”

“…9,18 However, these domain-wallrelated effects will not be discussed here. Since intrinsic effects will be dominant in most cases, calculations of piezoelectric coefficients along nonpolar directions based on single-domain data are still useful in predicting the properties of domain-engineered crystals.…”