Effect of lanthanum substitution on structural, dielectric and piezoelectric properties of (Na0.41K0.09Bi0.5)TiO3: A lead-free piezoelectric material. (August 2019)

• Record Type: Journal Article
• Authors: Singh, Gurvinderjit; Singh, A.K.; Selvamani, Rachna; Tiwari, V.S.; Karnal, A.K.
• Is Part Of: Solid state communications. Volume 298(2019)
• Publication Date: 2019-08
• Subjects: Ferroelectrics -- NBT -- X-ray diffraction -- Dielectric -- Piezoelectric; Solid state chemistry -- Periodicals; Solid state physics -- Periodicals; Chimie de l'état solide -- Périodiques; Physique de l'état solide -- Périodiques; 530.41
• DOI: 10.1016/j.ssc.2019.05.008
• Languages: English
• ISSNs: 0038-1098

Abstract

Abstract: The effect of lanthanum doping (0.5–5 mol%) on structural, dielectric and piezoelectric response of (Na0.41 K0.09 Bi0.5 )TiO3 ceramic has been investigated. The x-ray studies reveal that there is no structural transformation with incorporation of lanthanum. However, a gradual lowering of tetragonal-to-rhombohedral transitions and depolarization temperature was observed in the dielectric response. For lower lanthanum contents (0–2 mol%) the piezoelectric coefficients i.e d33 (150 pC/N) and kp (0.31) are nearly same. A significant decrease of d33 and kp was observed for higher lanthanum doping with emergence of pinched P-E hysteresis loop. These results are explained on the basis of disruption of long-range ferroelectric ordering in (Na0.41 K0.09 Bi0.5 )TiO3 with lanthanum doping as well as with emergence of anti-ferroelectric ordering. A structural phase diagram has also been derived for lanthanum doped (Na0.41 K0.09 Bi0.5 )TiO3 using dielectric measurements. Highlights: The structural, dielectric and piezo-electric response of lanthanum (La) substituted (Na0.41 K0.09 Bi0.5 )TiO3 ceramic has been investigated. A gradual lowering of tetragonal-to-rhombohedral phase transitions and depolarization temperature was observed. Using dielectric response a structural phase diagram has been derived. A pinched hysteresis loop for higher La content (5 mol%). For lower La contents (0–2 mol%) the piezoelectric coefficients are nearly same. A significant decrease of piezoelectric coefficients values was observed higher La doping. The results are explained on the basis of disruption of long-range ferroelectric ordering with La doping as well as with emergence of anti-ferroelectric ordering.