Dr. Andrew Bell

Abstract

This presentation will tell the story of how a curiosity-driven, ferroelectric materials research topic developed into a $2 million p.a. business, manufacturing industrial ultrasound transducers for use under extreme conditions. On that journey we discovered some interesting materials science, we learnt how to process materials on the edge of instability, we overcame our academic sensitivities in order to finance a spin-out company and followed some unexpected paths to gain moderate commercial success. The talk aims to provide a contemporary and perhaps idiosyncratic view of both the science and business of piezoelectric materials.

BiFeO3-PbTiO3 is a ferroelectric solid solution with a morphotropic phase boundary (MPB) between the perovskite rhombohedral and tetragonal phases. It has a number of interesting features including the high Curie temperature (635°C at the MPB), an unprecedented spontaneous strain (≈20%) on the tetragonal side of the MPB and the >300 K discontinuity in the antiferromagnetic Néel temperature across the MPB. These features provide a number of exciting opportunities in terms of exploiting the high temperature piezoelectricity and coupling the antiferromagnetism to strain and electric field, whilst the extreme tetragonality provides challenges in materials fabrication. Whilst studying these features the Functional Ceramics Group at the University of Leeds discovered methods to overcome the technical barriers to exploiting the piezoelectric properties and to produce materials capable of “PZT-like” performance up to and beyond 500°C.

As most established piezoelectric materials producers felt that BiFeO3 might be a challenge too far, the University supported the founding of a company, funded by venture capital and private finance, to commercialise the new material. Although there was a market ready for devices spanning the materials’ temperature capability, no potential customers had the capability to build the material into high temperature transducers. Hence, what started as a materials company transformed into a device company, with products in the industrial ultrasound, automotive, aerospace and electronics sectors.