Prohibition sign with the word "lead" and a red slash

Sept. 30, 2025

Applications

  • High-response, lead-free piezoelectrics
  • Advanced medical instrumentation
  • Ultrasonic imaging systems
  • Compact actuators in industrial processes

Advantages/Benefits

  • Enhanced piezoelectric response
  • Scalable thin film growth 
  • Environmental compliance
  • Ferroelectric-induced piezoelectricity

Background

The increasing demand for piezoelectric materials in various applications faces a significant challenge due to the environmental and health concerns associated with conventional lead-based compounds. While efforts have been made to develop lead-free alternatives, these often struggle to match the performance of their lead-containing counterparts. There is a need for technologically promising, yet metastable, polymorphs of potential lead-free materials.

Technology Overview

Scientists at Lawrence Berkeley National Laboratory and National Renewable Energy Laboratory have jointly developed a metastable, lead-free piezoelectric polymorph of strontium hafnate (SrHfO3) in its polar tetragonal P4mm phase. This phase, predicted by first-principles calculations to exhibit strong piezoelectricity, is synthesized as approximately 35 nm thick films via pulsed laser deposition on (001) SrTiO3 substrates. Computational optimization identified SrTiO3 as the optimal substrate, providing the necessary epitaxial strain and a weakly polar interface to stabilize the P4mm phase, which is energetically metastable compared to other SrHfO3 polymorphs. Structural characterization confirmed the epitaxial growth of the P4mm phase, while second harmonic generation verified its non-centrosymmetric, polar nature. 

Electrical measurements demonstrated ferroelectric behavior and a measurable piezoelectric response of 5.2 pm/V after electrical poling, confirming the predicted multifunctionality.

Inventors

  • Lauren Garten (NREL)
  • David Ginley (NREL)
  • Kristin Persson (LBNL)
  • Shyam Dwanakath (LBNL)

For More Information

Garten, L. et al, (2018). Theory-Guided Synthesis of a Metastable Lead-Free Piezoelectric Polymorph, Advanced Materials, Volume 30

Status

US Patented: US11335845B2