Dielectric, piezoelectric, and elastic properties of K_0.8Na_0.2NbO₃ single crystals

Abstract

A high-quality and large-sized K 0.8 Na 0.2 NbO 3 single crystal was successfully grown using the top-seeded solution growth method (TSSG). The temperature dependence of the dielectric during the cooling and heating of [001] C -and [011] C -oriented K 0.8 Na 0.2 NbO 3 single crystals was investigated. In order to better understand the crystal's piezoelectric properties, the complete and consistent set of dielectric, piezoelectric, and elastic constants of the [001] C -poled K 0.8 Na 0.2 NbO 3 single crystal was measured for the first time, using ultrasonic and resonance methods. A large elastic stiffness constant value of -E 11 10 2 ‡ Hao. T and C. P. Hu contributed equally to this work. NbO 3 single crystal also exhibited high electromechanical coupling coefficients (k 15 = 0.448, k t = 0.67). In addition, a comparison between the calculated and measured material constants confirmed that the orientation effect primarily contributes to the characteristics of the crystal. Fig. 2. Photograph of K 0.8 Na 0.2 NbO 3 single crystal grown via TSSG. FIG. 3. Temperature dependence of dielectric constants of [001] C -and [011] C -oriented K 0.8 Na 0.2 NbO 3 single crystals at 10-kHz frequency, for heating and cooling processes.

Advanced Synthesis on Lead‐Free KxNa(1−x)NbO3 Piezoceramics for Medical Imaging Applications

“…The crystals were grown along the [001] c direction and showed a large longitudinal electromechanical coupling factor k 33 %83% and a piezoelectric response of 255 pC N À1 , similar to that obtained for the same system prepared by conventional sintering. [68] Finally, interesting electromechanical coupling coefficients (k 15 ¼ 0.448, k t ¼ 0.67) were achieved by Tian et al, [69] which investigated a new stoichiometric system K 0.8 Na 0.2 NbO 3 single crystal using TSSG method.…”

“…Top-seeded solution growth method [69] K 0.5 Na 0.5 NbO 3 10 À6 80 Solid-state reaction pad-printing technique [70] (Na 0.535 K 0.485 ) 0. 95 [71] K 0.5 Na 0.5 NbO 3 --40 Solid state reaction electro-phoretic deposition [74] K 0.5 Na 0.5 NbO 3 / Bi 0.5 Na 0.5 TiO 3 170-320 À50, À60 270 Solid state reaction/sol gel [75] (Na 0.52 K 0.…”

Local Piezoelectric Behavior of Potassium Sodium Niobate Prepared by a Facile Synthesis via Water Soluble Precursors

“…For these reasons, in the last years, the attention of the scientific community and industries has been directed to alternative lead‐free systems . To this regard, undoped and doped KxNa1‐xNbO3 (KNN) systems attracted growing interest as promising candidates due to their excellent piezoelectric properties (390–570 pC N −1 ) by forming new phase boundaries, good electromechanical constants (K 33 83%) and high Curie temperature (T 200–420 °C) . From a crystallographic point of view, KNN presents orthorhombic crystal structure at room temperature and two phase transitions at higher temperatures, orthorhombic to tetragonal at T O − T = 200 °C and tetragonal to cubic at T T − C = 420 °C, respectively.…”

“…[6] To this regard, undoped and doped KxNa1-xNbO3 (KNN) systems attracted growing interest as promising candidates due to their excellent piezoelectric properties (390-570 pC N À1 ) by forming new phase boundaries, good electromechanical constants (K 33 83%) and high Curie temperature (T 200-420 C). [7][8][9][10][11] From a crystallographic point of view, KNN presents orthorhombic crystal structure at room temperature and two phase transitions at higher temperatures, orthorhombic to tetragonal at T OÀT ¼ 200 C and tetragonal to cubic at T TÀC ¼ 420 C, respectively. Above this last temperature, the sample loses its piezoelectric propriety.…”

Temperature‐ and E‐field‐dependent domain configuration and electrical properties in (K, Na, Li)(Nb, Ta, Sb)O3 single crystal

“…Among all lead‐free candidates, (K, Na)NbO 3 (KNN) family, owning a high dielectric and piezoelectric properties, large electromechanical coupling coefficient, and high Curie temperature, has been considered to be one of the most promising systems to substitute for Pb‐based materials. In the last decade, numerous researches have been carried out in order to enhance the piezoelectric performance of KNN family and some significant breakthroughs have been achieved, most of which are focused on the composition optimization, phase boundary design, and preparation technique modification . It is well‐known that piezoelectric and dielectric responses originate from the intrinsic and extrinsic contributions: the intrinsic one is from local atomic displacement within the unit cell, while the extrinsic one is attributed to the motion of domain wall relating to the domain structure.…”