Updated: Jun 14, 2026

Characterization of Full Set Material Constants and Their Temperature Dependence for Piezoelectric Materials Using Resonant Ultrasound Spectroscopy
Published on: April 27, 2016
1Multi-disciplinary Materials Research Center and State Key Lab of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, 710049, China.
This study introduces a new lead-free ceramic material with a high piezoelectric coefficient. The material is composed of barium titanate and barium calcium titanate. The researchers found that when the material is near a special point where three phases meet, it shows excellent piezoelectric properties. This point is called a tricritical triple point. The material's performance is due to its ability to switch between two crystal structures when an electric field is applied. The team predicts that in single-crystal form, the material could be even more effective. Their findings may help in designing new lead-free materials with strong piezoelectric responses.
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Area of Science:
Background:
Current piezoelectric materials often rely on lead-based compounds, which pose environmental and health risks. While alternatives exist, they typically exhibit lower performance than lead-based systems. The search for lead-free materials with high piezoelectric coefficients remains a significant challenge. Existing research has identified morphotropic phase boundaries (MPBs) as promising regions for enhanced piezoelectricity. However, the mechanisms behind MPB-driven performance in lead-free systems are not fully understood. Prior studies have shown that MPBs can arise from proximity to triple phase points, but this has been primarily explored in lead-based systems. No prior work had resolved how triple phase points might influence lead-free ceramics. This gap motivated the investigation of a new lead-free system with a tricritical triple point (TCP).
Purpose Of The Study:
The study aimed to explore a novel lead-free ceramic system with a tricritical triple point to achieve high piezoelectric performance. The researchers sought to determine whether proximity to a TCP could enhance piezoelectric coefficients in a lead-free material. They focused on the Ba(Ti(0.8)Zr(0.2))O(3)-(Ba(0.7)Ca(0.3))TiO(3) system, which had not been previously tested for piezoelectric properties. The goal was to identify optimal compositions that exhibit high d(33) values. The team also aimed to understand how the TCP influences polarization behavior. Their work was driven by the need for environmentally friendly materials with strong piezoelectric responses. This study may provide insights into designing lead-free ceramics with performance rivaling lead-based systems.
The optimal composition achieved a d(33) coefficient of approximately 620 pC/N.
The d(33) value of 620 pC/N is comparable to some lead-based materials.
The MPB proximity to the TCP reduces polarization anisotropy, enabling polarization rotation.
The MPB facilitates polarization rotation between rhombohedral and tetragonal states.
Main Methods:
The researchers synthesized and characterized a Ba(Ti(0.8)Zr(0.2))O(3)-(Ba(0.7)Ca(0.3))TiO(3) ceramic system. They used powder X-ray diffraction to analyze phase transitions and determine the phase diagram. Polarization measurements were conducted to assess the material's response to electric fields. The d(33) coefficient was measured using a standard piezoelectric d(33) meter. The team identified the optimal composition by varying the ratios of the two components. They examined the material's behavior near a tricritical triple point of three phases: cubic paraelectric, ferroelectric rhombohedral, and tetragonal. The proximity to this triple point was linked to polarization anisotropy and rotation. Theoretical predictions were used to estimate the potential d(33) values in single-crystal form.
Main Results:
The optimal composition of the ceramic system exhibited a d(33) coefficient of approximately 620 pC/N, a value comparable to some lead-based materials. The phase diagram revealed a morphotropic phase boundary (MPB) originating from a tricritical triple point (TCP). The MPB compositions showed minimal polarization anisotropy, enabling easy polarization rotation between rhombohedral and tetragonal states. This behavior was attributed to the proximity of the MPB to the TCP. Theoretical predictions suggested that single-crystal forms of the material could reach d(33) values of 1500–2000 pC/N. The material's performance was linked to the interplay of three phases at the TCP. These results suggest that TCP-based MPBs may be a general strategy for enhancing piezoelectricity. The findings may guide the design of new lead-free materials with high performance.
Conclusions:
The study demonstrated that a lead-free ceramic system can achieve a high d(33) coefficient of 620 pC/N through proximity to a tricritical triple point. The material's performance was attributed to the morphotropic phase boundary (MPB) and its influence on polarization rotation. The researchers propose that MPBs derived from TCPs may be a general approach for enhancing piezoelectricity in both lead-free and lead-based systems. Their findings suggest that TCP-based MPBs can reduce polarization anisotropy and facilitate polarization rotation. The predicted d(33) values for single-crystal forms of the material are significantly higher than the polycrystalline version. These results may inform the development of new materials with high piezoelectric coefficients. The authors suggest that this approach could be applied to other systems to achieve similar performance. Their work may provide a new framework for designing lead-free piezoelectric materials.
Theoretical predictions suggest d(33) values of 1500–2000 pC/N in single-crystal form.
The authors suggest that TCP-based MPBs may be a general strategy for enhancing piezoelectricity.