Aspect ratio dependence of electromechanical coupling coefficient of piezoelectric resonators

2005 ◽  
Vol 87 (13) ◽  
pp. 132901 ◽  
Author(s):  
Moojoon Kim ◽  
Jungsoon Kim ◽  
Wenwu Cao
2011 ◽  
Vol 22 (16) ◽  
pp. 1879-1886 ◽  
Author(s):  
Clark Andrews ◽  
Yirong Lin ◽  
Haixiong Tang ◽  
Henry A. Sodano

Piezoelectric ceramics offer exceptional sensing and actuation properties, however, they are prone to breakage and are difficult to apply to curved surfaces in their monolithic form. One method to alleviate these issues is through the use of 0–3 active composites, which are formed by embedding piezoelectric particles into a polymer matrix that protects the ceramic from breaking under mechanical loading. This class of material offers certain advantages over monolithic materials; however, they have seen little use due to the low electromechanical coupling offered by these materials. Here, we demonstrate that by controlling the aspect ratio of the filler, the electromechanical coupling coefficient can be significantly improved. For all volume fractions tested, nanocomposites with high aspect ratio lead nanowires filler had higher coupling with increases as large as 2.3 times. Furthermore, the nanocomposite’s coupling was more than 50% of the piezoceramic fillers’ when nanowires were used.


2016 ◽  
Vol 848 ◽  
pp. 339-343
Author(s):  
Xiao Kun Zhao ◽  
Bo Ping Zhang ◽  
Lei Zhao ◽  
Li Feng Zhu

The modified behavior of the phase transition temperatures (TO-T and/or TC) between orthorhombic (O), tetragonal (T) and cubic (C) that caused by doping Sb5+ in (Li0.052Na0.493K0.455)(Nb1-xSbx)O3 (LNKNSx) ceramics was reported in the present investigation. The results show that differing from the insensitive TO-T to the Sb5+ content, TC splits into two peaks TCI and TCII when doping Sb5+. The decreased TCI by raising x may be ascribed to the Sb-rich grains and the settled TCII round 480 °C resulting from the Sb-lack ones. The enhanced piezoelectric coefficient d33 value of 263 pC/N and planar mode electromechanical coupling coefficient kp value of 42.5% at x=0.052 can be attributed to the polymorphic phase boundary (PPB) behavior with an appropriate ratio between T and O phases without any second phase.


2018 ◽  
Vol 29 (20) ◽  
pp. 3949-3959 ◽  
Author(s):  
Adriane G Moura ◽  
Alper Erturk

We establish and analyze an analytical framework by accounting for both the piezoelectric and flexoelectric effects in bimorph cantilevers. The focus is placed on the development of governing electroelastodynamic piezoelectric–flexoelectric equations for the problems of resonant energy harvesting, sensing, and actuation. The coupled governing equations are analyzed to obtain closed-form frequency response expressions via modal analysis. The combined piezoelectric–flexoelectric coupling coefficient expression is identified and its size dependence is explored. Specifically, a typical atomistic value of the flexoelectric constant for barium titanate is employed in the model simulations along with its piezoelectric constant from the existing literature. It is shown that the effective electromechanical coupling of a piezoelectric material, such as barium titanate, is significantly enhanced for thickness levels below 100 nm. The electromechanical coupling coefficient of a barium titanate bimorph cantilever increases from the bulk piezoelectric value of 0.065 to the combined piezoelectric–flexoelectric value exceeding 0.3 toward nanometer thickness level. Electromechanical frequency response functions for resonant power generation and dynamic actuation also capture the size-dependent enhancement of the electromechanical coupling. The analytical framework given here can be used for parameter identification and design of nanoscale cantilevers that can be used as energy harvesters, sensors, and actuators.


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