Cold Sintering of Piezoelectric Composites

This overseas travel grant will enable Dr. James Roscow (University of Bath) to visit and collaborate with Professor Clive Randall's group at Penn State University (PSU), USA, to investigate the use of the Cold Sintering Process (CSP) as a novel method for fabricating piezoelectric ceramic-based composites for ultrasonic transducer applications. The manufacturing of ceramics is an energy intensive process that had changed little in the past 10,000 years until the recent development of CSP by Randall's group (first papers published in 2016). Conventionally, inorganic ceramic materials with high melting points in a powder form are shaped, either with the aid of a liquid to form a slip before casting or through compaction under pressure, before first drying and then firing (sintering) at high temperatures (>1000 C) to consolidate and densify the polycrystalline structure. CSP, on the other hand, uses the controlled introduction of a liquid phase into the organic powder prior to the simultaneous application of pressure (typically 100-300 MPa) and moderate temperatures (~200 C) to densify the ceramic. As such, CSP has the potential to reduce the required energy for fabricating piezoelectric ceramics, and composites derived there-of, by more than 50% compared to traditional high temperature sintering approaches. Furthermore, this technique enables the direct co-sintering of ceramic and polymer phases, reducing the need for post-machining process that increase the cost of fabricating piezoelectric composites, which are widely used in medical ultrasound and SONAR devices. This overseas travel grant aims to bring together the PI's expertise in the microstructure-property relationships of piezoelectric composites with Prof. Randall's world leading expertise in the low energy processing and properties of functional ceramics, and will constitute a new collaboration between an Early Career Research, Dr. Roscow, and Prof. Randall's world leading research group at PSU.

In the short and medium term, the research enabled by the overseas travel grant will lead to the publication of an academic paper in a relevant journal, which will directly impact upon academic beneficiaries, as well as reporting this work at international conferences, such as the International Symposium on the Application of Ferroelectrics (ISAF) and Materials Research Society (MRS) annual meeting in 2021. The work will improve the PI's knowledge and understanding of the Cold Sintering Process (CSP) and enable the implementation of CSP capabilities at the University of Bath to continue research in this field, in the form of a EPSRC standard mode grant application that will be submitted by the PI within six months of the end of the visit. The grant will impact directly the PI's (an Early Career Researcher) career by providing links to a world leading research group and their facilities and initiating a new collaboration.

In the longer term, developing new low energy and low waste fabrication techniques to produce piezoelectric composites will benefit UK materials manufacturers, such as CeramTec and Ionix, and end-users of these technologies, such as Thales UK, Seiche, Metrol and Silent Sensors, among others. Reducing the energy costs associated with fabricating piezoelectric ceramics and composites will have both a positive environmental impact and reduce the cost required to manufacture devices that rely on these materials, particularly for medical imaging and SONAR. Further fundamental work, however, is required to fully understand the interplay between processing, microstructure and properties of these materials, which will start to be addressed in this project.