Modified energy harvesting figures of merit for stress- and strain-driven piezoelectric systems

Piezoelectrics are an important class of materials for mechanical energy harvesting technologies. In this paper we evaluate the piezoelectric harvesting process and define the key material properties that should be considered for effective material design and selection. Porous piezoceramics have bee...

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Bibliographic Details
Published in:The European physical journal. ST, Special topics Special topics, 2019-08, Vol.228 (7), p.1537-1554
Main Authors: Roscow, James I., Pearce, Holly, Khanbareh, Hamideh, Kar-Narayan, Sohini, Bowen, Chris R.
Format: Article
Language:English
Subjects:
Atomic
Classical and Continuum Physics
Condensed Matter Physics
Coupling coefficients
Energy
Energy conversion efficiency
Energy harvesting
Energy Harvesting and Applications
Figure of merit
Finite element method
Material properties
Materials Science
Measurement Science and Instrumentation
Mechanical properties
Molecular
Optical and Plasma Physics
Physics
Physics and Astronomy
Piezoelectric ceramics
Piezoelectricity
Porosity
Porous materials
Reduction
Regular Article
Strain
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Summary:Piezoelectrics are an important class of materials for mechanical energy harvesting technologies. In this paper we evaluate the piezoelectric harvesting process and define the key material properties that should be considered for effective material design and selection. Porous piezoceramics have been shown previously to display improved harvesting properties compared to their dense counterparts due to the reduction in permittivity associated with the introduction of porosity. We further this concept by considering the effect of the increased mechanical compliance of porous piezoceramics on the energy conversion efficiency and output electrical power. Finite element modelling is used to investigate the effect of porosity on relevant energy harvesting figures of merit. The increase in compliance due to porosity is shown to increase both the amount of mechanical energy transmitted into the system under stress-driven conditions, and the stress-driven figure of merit, FoM 33 X , despite a reduction in the electromechanical coupling coefficient. We show the importance of understanding whether a piezoelectric energy harvester is stress- or strain-driven, and demonstrate how porosity can be used to tailor the electrical and mechanical properties of piezoceramic harvesters. Finally, we derive two new figures of merit based on the consideration of each stage in the piezoelectric harvesting process and whether the system is stress- ( F ij X ), or strain-driven ( F ij x ).
ISSN:1951-6355
1951-6401
DOI:10.1140/epjst/e2019-800143-7