Crystal growth and electric‐property change by rubidium or cesium doping on potassium‐sodium‐niobate

Abstract

Alkali metals (Na, Rb or Cs) co-doped with fiber-and bulk-shaped KNbO 3 single crystals were grown using two original methods by means of doping together of small ionic Na and large ionic Rb or Cs into KNbO 3 . Single-phase crystals could be grown with an orthorhombic system at room temperature as well as pure KNbO 3 . Piezoelectric and ferroelectric property changes by the co-doping of Rb or Cs with Na were estimated using d 33 values and a polarization-electric field hysteresis curve in fiber-and bulk-shaped crystals.

Using Feature‐Assisted Machine Learning Algorithms to Boost Polarity in Lead‐Free Multicomponent Niobate Alloys for High‐Performance Ferroelectrics

“…[6,[9][10][11][12] In this regard, the successful tuning of ferroelectric properties based on A-site substitution has set a strong platform for multicomponent A-site engineering of KNO for enhanced/boosted ferroelectric and piezoelectric performance. [10,[13][14][15][16][17] In the same vein of thought, experiments on the (K,Li,Na)NbO 3 ternary alloy system have shown a promising enhancement of electromechanical properties. [13,14] Furthermore, other chemical variants of KNO-based alloys, such as (K,Na,Rb)NbO 3 and (K,Na,Cs)NbO 3 , have also been investigated for their improved single crystal growth via balancing the ionic radius differences between the co-dopants.…”

Potential Advantage of Multiple Alkali Metal Doped KNbO3 Single Crystals

“…The polarization was weak and was less than 0.4 µC/cm 2 for a ferroelectric material. The conventional KN single crystal has a small 20 µC/cm 2 value [43]. Thus the KN4617 crystal did not affect the ferroelectric properties of KN that much, even although it was formed at the same time during the crystal growth.…”

“…The P-E hysteresis loop on bulk crystals is shown in Figure 13 [43], the ferroelectric properties were not really improved. On the other hand, compared with the bulk, the fiber crystal has better ferroelectric properties on remnant polarization although the coercive electric field is large.…”

“…KN series crystals with multi alkali metal ions, especially on KNRN, are promising Pb-free crystals for ferroelectric and piezoelectric crystals. We also grew single crystals using the tube seed Czochralski method (Tube-Cz) for bulk shapes [43]. Larger diameter crystals were obtained.…”

“…Amounts of Na, Rb, or Cs also reached 10-20 mol% in the alkali metals of K-Na-A (A: Rb or Cs). Figure 12 shows typical crystals grown by the Tube-Cz method on KN, KNRN and KNCN [43]. The c-axis was easily estimated from the rectangular crystal habit.…”