Open AccessTextured, lead-free piezoelectric ceramics with high figure of merit for energy harvesting
Author(s) -
Astri Bjørnetun Haugen,
Erling Ringgaard,
Franck Levassort
Publication year - 2021
Publication title -
jphys materials
Language(s) - English
Resource type - Journals
ISSN - 2515-7639
DOI - 10.1088/2515-7639/ac0595
Subject(s) - piezoelectricity , materials science , figure of merit , poling , ceramic , texture (cosmology) , dielectric , composite material , tape casting , relative permittivity , energy harvesting , grain size , sintering , permittivity , energy (signal processing) , ferroelectricity , optoelectronics , statistics , image (mathematics) , mathematics , artificial intelligence , computer science
Piezoelectrics are key materials for energy conversion, for example in ultrasound transducers and energy harvesters. This work presents the synthesis and characterization of the lead-free piezoelectric composition (Li 0.06 (K 0.52 Na 0.48 ) 0.94 )(Nb 0.71 Ta 0.29 )O 3 doped with 0.25 mol% Mn (KNNLTM) as textured ceramics. Templated grain growth from NaNbO 3 platelet templates aligned by tape casting was used to introduce texture, and after sintering for 14 h at 1100 °C this produced up to 84% (100) pc grain orientation. After high temperature poling, the textured samples exhibit reasonable piezoelectric response with d 33 values up to 171 pC N −1 , and k t values of 0.35, which is 71% of the response obtained in a single crystal of the same composition. The low relative dielectric permittivity of the textured and high temperature-poled KNNLTM ( ϵ 33 T / ϵ 0 down to 182) resulted in record-high piezoelectric voltage constants ( g 33 up to 101 mV m N −1 ), higher than previously reported for lead-free piezoelectric ceramics, as well as very high figure of merit ( d 33 g 33 up to 16 × 10 −12 m 3 J −1 ) for non-resonant energy harvesting in compression. These numbers make the textured KNNLTM materials of this work highly promising for use in thickness mode, non-resonant piezoelectric energy harvesters.