Properties of textured piezoceramics measured with miniature samples

Alexandrou, Anna; Cochran, Sandy; OLeary, Richard; Fotouhi, Sakineh

Abstract

Background, Motivation and Objective: Piezoelectric materials carry intrinsic elastic-piezoelectric-dielectric (EPD) properties, typically represented in matrix form, which make them crucial for various technological fields. They are usually employed in the form of sensors, actuators, and energy harvesters. Advances in these materials is important for devices to achieve better performance. Piezocrystals have been extensively researched and demonstrated superior properties against polycrystalline material, but their challenging and expensive production processes make them impractical for industrial applications. This is motivating exploration of alternatives, with textured piezoceramics one promising option.
Material characterization is a critical phase in understanding specific properties and behaviors of piezoelectric materials and it further enables virtual prototyping, whether the material are used independently or integrated into devices. Conventional methods to obtain the full EPD matrix follow an IEEE standard which involves analysing and combining electrical impedance spectrograms (EIS) from multiple samples with specific geometries. Although this has been the most popular method for more than six decades, concerns arise regarding the cost, material waste, inconsistencies among samples, and impracticality for material testing under external pressure and high temperatures. Our objective is therefore to develop a better alternative.
Statement of Contribution and Methods: Previous work proposed an alternative method employing a single sample, typically shaped as a cube with millimetre-scale edges. This approach combines EIS with resonant ultrasound spectroscopy (RUS) and an optimization algorithm to derive EPD properties. Despite eliminating the need for multiple samples, challenges in preparation and poling thick samples introduce measurement inaccuracies associated with RUS.
In our study, the complete EPD matrix of textured PMN-PT piezoceramics (CTS Ferroperm, Kvistgaard, Denmark) is obtained using a single miniature sample cube of just 1 mm side. For this, only EIS and an optimisation algorithm built on MATLAB and finite element analysis (FEA) (OnScale, Atlanta, GA, USA) are employed. The material was also characterized using the IEEE standard method, and COMSOL (COMSOL Ltd, Cambridge, UK) was used as an additional FEA tool for validation.
Results and Discussion: Results from this work show textured piezoceramics to carry promising properties. Key material properties include 𝑔33=35×10−3 𝑉𝑚/𝑁, which exceeds other conventional piezoceramic material, and 𝑑33=610 𝑝𝐶/𝑁. Results of interest are also obtained in the coupling coefficients with values 𝑘33=0.82, and 𝑘31=0.53, while 𝑘𝑡=0.56, and 𝑘𝑝=0.71. However, shear properties are relatively low. Overall, results from this work justify the potential of textured piezoceramics as an alternative to piezocrystals. The comparison will be completed by fabrication of single element transducers made of piezocrystal, conventional PZT-5A and the available textured piezoceramic with the aim to illustrate performance both in the lab and in practice.

• Presentation Conference Type: Conference Abstract
• Conference Name: 2024 Ultrasonics, Ferroelectrics, and Frequency Control Joint Symposium (UFFC-JS)
• Start Date: Sep 22, 2024
• End Date: Sep 26, 2024
• Acceptance Date: Aug 14, 2024
• Deposit Date: Sep 6, 2024
• Peer Reviewed: Peer Reviewed
• Public URL: https://uwe-repository.worktribe.com/output/12842847