Textured, lead-free piezoelectric ceramics with high figure of merit for energy harvesting. (15th June 2021)

• Record Type: Journal Article
• Authors: Haugen, Astri Bjørnetun; Ringgaard, Erling; Levassort, Franck
• Is Part Of: JPhys materials. Volume 4:Number 4(2021)
• Publication Date: 2021-06-15
• Subjects: piezoelectricity -- texture -- lead-free -- energy harvesting -- voltage constants; Solid state physics -- Periodicals; Materials science -- Periodicals; 530.41
• DOI: 10.1088/2515-7639/ac0595
• Languages: English
• ISSNs: 2515-7639

Abstract

Abstract: 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 (Li0.06 (K0.52 Na0.48 )0.94 )(Nb0.71 Ta0.29 )O3 doped with 0.25 mol% Mn (KNNLTM) as textured ceramics. Templated grain growth from NaNbO3 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.