Engineering Fellowships for Growth: Polar Materials for Additive Manufacturing

Lead Research Organisation: University of Leeds
Department Name: Chemical and Process Engineering


The concept of Additive Manufacturing (AM) is seen as an important contributor to the re-balancing of UK manufacturing industry. AM enables the manufacture of complex structures with novel combinations of materials, to create innovative products for both the consumer and industrial markets. It can be applied equally to mass-production or bespoke products. The intrinsic economy of raw material usage keeps costs low and the rapid turn-round of design iterations minimizes the time to market for new products. Due to progress in organic conductors and semiconductors, the concept of plastic electronics is a major contributor to multifunctional products using AM. These advances are evident in many consumer products including smartphones and tablet PCs. The proposed Fellowship is intended to address a capability gap in AM and flexible electronics.
The missing capability is in the AM-compatible integration of highly polar solids, as used in capacitors, piezoelectric devices and infra-red sensors. These functions are normally satisfied by ferroelectric oxides (e.g. barium titanate and PZT) in the form of ceramics which are sintered at high temperature, and can currently only be deployed in the form of discrete components. This limits both the flexibility and potential cost-savings offered by AM. Printable organic materials, as used in photonic functions, do not provide an acceptable solution to the demand for such highly polar dielectrics as the relevant figures of merit are one or two orders of magnitude lower than oxides. Capacitors and piezo-transducers are ubiquitous in conventional electronics and the ability to design them into printable products is a "must have" for future AM systems, allowing full integration of pressure sensors, energy harvesting and energy storage capacitors, for example.
The project will employ a bottom-up, holistic approach with three innovations: (i) the preparation of highly crystalline, monodisperse, ferroelectric nanocrystals, (ii) the implementation of multi-scale modelling for the optimal design of printable, high-polarisability devices and (iii) utilization of ferroelectric polarization to promote self-assembly of nanocrystals into functionally beneficial crystallographic orientations during printing operations. These innovations will be employed to design new printable functional components that can be integrated into electromechanical products produced by AM techniques. A successful outcome will result in reduced costs and lead times for integrating new functional materials into AM products. The Fellowship will also be used as a platform to (i) initiate programmes on new applications of ferroelectric nanocrystals and (ii) facilitate the re-focusing of functional oxide research on goals coherent with medium to long-term UK industry needs.

Planned Impact

In September 2012, the Technology Strategy Board reported "if current technological and commercial barriers can be overcome, the future Additive Manufacturing sector could be worth in excess of $100 billion per annum by 2020". The same report identified 13 strategic goals "to help the UK consolidate its current position in AM, open new markets and build a competitive advantage for the future". Two of these goals were: "lower cost raw materials in a larger number of different varieties" and "materials that are optimised for AM processes". The proposed Fellowship is intended to address those goals by filling a capability gap in AM and flexible electronics. The main aim of the proposed project is to make available highly polarizable materials in a form compatible with the methods of Additive Manufacturing. The project is designed to profit UK manufacturing industry by providing new materials that can be integrated into products produced by AM techniques, providing greater functionality at reduced cost.

Three demonstrator materials have been selected due to their potential for near-term applications in a wide range of systems; these are energy storage capacitors, piezoelectric sensors and piezoelectric energy harvesting devices.

The current $466m p.a. demand for energy storage capacitors is due to double by 2018. The majority of these are based on electrolytic "supercapacitors" and are not compatible with AM manufacturing processes. Ceramic capacitors which are already ubiquitous in electrotechnology with 10,000 billion units produced annually worldwide are available mainly in the form of surface mount devices, but with energy densities lower than those of supercapacitors.. The project aims to develop ceramic composite capacitors that exhibit energy densities closer to those of supercapacitors but in AM-compatible formats.
The conventional piezoelectric materials and devices market is worth approximately $15bn p.a., with ~10% annual growth due to the development of new areas of application. Energy harvesting, for the provision of low power for wireless electronics, is predicted to be the fastest growing sector. The current world market for all forms of energy harvesting devices is $130m p.a and is projected to growth to $4bn p.a. by 2019.
The project will benefit a number of industry sectors including automotive, ICT, medical devices, consumer electronics and robotics. Specific beneficiaries will include Original Equipment Manufacturers in these sectors and Tier 1 & 2 companies within the supply chains through the ability of providing innovative products with increased functionality at lower cost than current products. The eventual beneficiary will be the consumer.

The impact plan will focus on maximising the commercial impact of the selected materials/devices and to ensure the direction of the development of these exemplars is consistent with industry needs and with the state of the art in AM practice, a number of measures will be undertaken:
(i) appointment of an advisory group comprising representatives from industrial stakeholders to ensure that opportunities for impact, particularly industrial exploitation, are maximized;
(ii) liaison with recognized centres of excellence in the field will be vital in ensuring that advances made in the project are coherent with current and future practice;
(iii) liaison with printing equipment and ink manufacturers will be held on a regular basis to ensure that the project assimilates good practice in printing technology and to provide an early opportunity for technology transfer;
(iv) the results of the programme will be widely publicised through engagement with the UK Additive Manufacturing community through the Add3D initiative ( and the series of international conferences that it promotes.
Description A thorough analysis of reaction pathways between simple and complex oxides during heat treatment, coupled with judicious choice of raw materials, allowed us to identify solid-state chemical routes that yielded fully crystalline nanoparticles of lead titanate and PZT suitable for ink-jet printing.Surprisingly far greater success was obtained using conventional calcination techniques than more sophisticated molten salt techniques.
Exploitation Route Use of the nanoparticle preparation techniques developed under this programme will allow ink-jet printing of ceramic-polymer composite layers suitable for pressure sensing with high spatial resolution.
Sectors Aerospace, Defence and Marine,Digital/Communication/Information Technologies (including Software),Electronics

Description The knowledge gained during the Fellowship period concerning the use and limits of ink-jet printing to create functional dielectric and ferroelctric films have been transferred to 3 industrial collaborators. In one case, the recommended processes are being implemented in current product developments. Further details are limited by NDAs.
First Year Of Impact 2020
Sector Aerospace, Defence and Marine,Digital/Communication/Information Technologies (including Software),Electronics
Impact Types Economic

Title Dataset associated with 'Effects of poling and crystallinity on the dielectric properties of Pb(In1/2Nb1/2)-Pb(Mn1/3Nb2/3)-PbTiO3 at cryogenic temperatures' 
Description We provide dielectric data (real permittivity, imaginary permittivity, relative permittivity, loss tangent) as a function of temperature and frequency for the relaxor-ferroelectric Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 with nominal composition 28%(PIN)-40%(PMN)-32%(PT). The data are for three samples: an (001) cut single crystal, a (111) cut single crystal, a polycrystalline ceramic. Permittivity data were measured for both a poled and depoled state for each sample, at cryogenic temperatures down to 20 K and above room temperature up to 800 K. Low temperature dielectric relaxation peak positions for the poled (001) crystal have been extracted and fitted to a Vogel-Fulcher function. The dielectric data are accompanied by room temperature characterisation of the piezoelectric charge coefficients. 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes