Balancing hyperbole and impact in research communications related to lead-free piezoelectric materials

  • Andrew J. BellEmail author
  • Dragan Damjanovic
Invited Viewpoint

We recall a recent PhD defense for a candidate who had undertaken some interesting work on a novel processing route for a class of functional materials. The candidate compared the figure of merit for his new material to that of a similar material that he had processed by conventional methods. The new process resulted in a value approximately half that of the conventional route, but the candidate still concluded that his new material exhibited excellent properties. When asked why he had written that statement, having clearly demonstrated the new route produced inferior properties to conventional materials, he was somewhat perplexed. He eventually explained that the new route may have energy saving advantages, albeit unquantified, and therefore, he could make that claim.

Was he justified in making that claim? In our opinion, the answer is no. Certainly, one should signpost the link to potential applications, but without undertaking a more detailed cost–benefit analysis, accounting for production costs and energy savings and the trade-off against materials performance, the claim of “excellent properties” is unjustified. Clearly, the student was not in a position to undertake that analysis, but it does not excuse the misrepresentation. However, the examiners did not press the matter and he successfully completed the examination. If he had made purely scientific conclusions that were both incorrect and unsubstantiated, he may have had a much more difficult time graduating.

But why did he do it? It was evident from his bafflement that the student was following the example set in countless papers published by career scientists. In an academic world in which job appointments, promotions and pay-rises are governed by impact factors and citation counts, it is difficult, even for those with the highest integrity, not to indulge in a little hyperbole concerning the potential socioeconomic impact of their results. To do so will help justify publication of the research in the leading journals and increase its academic impact. Qualitative claims of excellence and industrial importance are an easy and almost unverifiable way of adding more “substance” to an abstract or a conclusions section. To do any less would be tantamount to an admission that several man-years of valuable resource have been wasted. It is also in the Universities’ interests to maximize the apparent impact of their research outputs. With a keen eye on their position in national and international league tables, many institutions encourage their employees by advising on how to maximize the alleged impact potential of their work via press releases and social media.

It seems that it is also a practice that journal editors may tacitly encourage. In order to maintain their editorial policies, many top journals reject submissions, even manuscripts reporting excellent science, at the pre-refereeing stage, if they consider that the paper will have insufficient impact. Moreover, referees are mainly concerned with monitoring scientific rigor, and unless specifically selected for their industrial credentials, will seldom reject based on the non-scientific claims in the manuscript.

So, everyone appears to concur with the practice, therefore it must be OK.

Or is it? Can the exaggerated claims for the application potential of a material be detrimental? Surely, industrial scientists know their stuff and are capable of reading between the lines to make up their own minds about the potential of a piece of academic work? Yes, they can, but that is not where the problem lies. Where hyperbole becomes an issue is when non-experts are making decisions or recommendations based on information they read in the scientific literature. There are many recent, high-profile cases in which a large body of stakeholders lose trust in the opinions of scientists or experts. Examples for which significant fractions of public opinion differ from those of experts include climate change, nuclear power and MMR vaccines. In the run-up to the 2016 UK BREXIT referendum, a cabinet minister often noted for his intellectual rigor, when faced with the accusation that there were no expert opinions to support his pro-BREXIT stance, seriously remarked “people in this country have had enough of experts….” [1]. In the USA, the acceptance of “alternative facts” also appears to have originated in the popular distrust of expert opinion.

Our exemplar case is an issue that is outside of public debate, but is topical in materials science. It is one in which those with very limited understanding of the science may use the scientific literature to aid their decision-making. The decisions they make concern potentially serious public health and environmental issues in specific locations in the developing world, but will have implications for jobs and local economies in the industrial world. The example is the search for new, lead-free, piezoelectric materials.

In 2000, the EU’s Restriction of Hazardous Substances (RoHS) directive came into force [2]. RoHS, as it is known, limits the chemical concentration of a number of elements and organic substances in electrical and electronic equipment for sale in the EU. RoHS has served as a model for similar legislation in other areas of the world including Japan, China, Korea, central Asia and the Gulf states. Hence, the influence of RoHS is effectively worldwide. The directive restricts the use of component materials in which the lead content exceeds 0.1% by mass. It is important to understand that the directive was motivated not by any perceived risks in the manufacture or usage of components and equipment containing lead, but by the uncertainties of the disposal routes for such equipment at the end-of-life. So-called e-waste currently amounts to more than 50 million tons a year, a majority of which, despite widespread legislation to the contrary, is believed to be disposed of informally in landfill sites in the developing world [3]. Such sites are hosts to hundreds of informal recyclers, who aim to extract metals in commercially viable quantities, often with the aid of child labor. The pernicious nature of lead poisoning and its worryingly high incidence in the vicinity of such sites led to the inclusion of lead in the RoHS directive. Given the difficulties in policing end-of-life disposal, the directive seeks to limit the most dangerous elements at the source, by preventing their incorporation into products for sale in the EU. Since the introduction of RoHS, the lead content of electronics, as typified by the ubiquitous mobile phone, has fallen from > 1% to < 0.015%, mainly through the replacement of SnPb solder by lead-free alloys. The abandonment of cathode ray tubes as the visual display of choice for computers has also helped reduce the overall lead content of the e-waste stream. These reductions in lead content have been made despite the continued employment of lead in certain classes of use allowed by RoHS exemptions. These were established to allow for electrical and electronic functions that could not be achieved without lead at concentrations > 0.1%.

One such exemption is 7(c)-I, which covers the category of electroceramics exemplified by “piezoelectronic (sic) devices.” This exemption was introduced mainly because there was no available replacement for the class-leading piezoelectric material Pb(Zr,Ti)O3, known as PZT. Exemptions are reviewed periodically by Expert Groups appointed by the EU and aided by consultants who administer and report on stakeholder consultations that contribute to the review. In the case of exemption 7(c)-I, the Expert Group comprises environmental experts and civil servants rather than technology experts. Their reviews have taken place at 5-yearly intervals and have so far not recommended lifting of the exemption. However, continuation of the exemption is dependent upon the stakeholder industries engaging in research to identify alternative materials or technologies to replace the subjects of the exemption. In the case of piezoelectric materials, there has been a vigorous search for viable lead-free piezoelectric materials that could replace PZT. This has been an overwhelmingly academic activity, rather than industry led. An indicator of the level of activity is that since 2000, over 4000 journal and conference papers have been published on the topic of lead-free piezoelectrics and in 2018 over half the scientific publications on piezoelectric materials and devices included the keyword “lead-free” [4]. Naturally, a large number of these papers make unverifiable claims for the industrial significance of the reported research, and typically refer to how the reported material is an excellent candidate to replace PZT. These claims may be driven as much by a genuine ignorance of industrial needs as they are by the motive of creating or demonstrating impact.

Despite the significant expenditure and resource required to maintain this level of research, there are currently very few examples of commercially available lead-free piezoelectric materials. Sales of PZT are still orders of magnitude greater than those of the very small number of commercially available lead-free materials. There is a complex combination of factors that have inhibited the widespread industrial adoption of lead-free piezoelectric materials. However, the simplest conclusion is that no lead-free material has yet been demonstrated that can match the full set of required material specifications for major applications. There are certainly lead-free examples that can match or exceed one or two of the high-profile performance criteria of PZT (e.g., the piezoelectric charge coefficient), but when the full set of requirements are examined, these have either not been evaluated or do not make a sufficient case for replacement of PZT in the target applications. Any one of a score of factors might prohibit the use of such new materials on purely technical grounds, including processability, reproducibility and reliability—factors seldom assessed in academic research. Moreover, one should not underestimate the cost of approving a new material for a given application. This most probably involves the redesign and test the devices to adapt to the change of material specification. Unproven material sources and a complex intellectual property landscape are also inhibiting factors.

An issue which is only recently coming to light is that a lead-free material is not automatically environmentally benign. Increasing activity in life-cycle analysis and sustainability assessment is demonstrating that a number of the leading lead-free candidates have poorer environmental credentials than PZT [5, 6]. While researchers may not have been aware of this for most of the last 20 years, it is now something they need to assimilate into their research. With this in consideration, the inclusion of elements such as niobium and antimony may preclude compositions being considered by the Expert Group as suitable replacements for PZT.

Notwithstanding the comparatively small levels of lead in the current e-waste stream from piezoceramics, the next consultation on exemption 7(c)-I will start in 2020. The group of industry stakeholders will almost certainly argue in favor of a continuation of the exemption on the basis that there are no suitable replacement materials. The Expert Group and the associated consultants will have to examine that argument critically and no doubt will consult the scientific literature to determine its veracity. Of course, they will find hundreds of claims concerning how research on particular lead-free piezoelectric materials has resulted in materials ripe for commercial application. How will the group manage the apparent discrepancy between the industry arguments and the scientific literature? Suspicious of industry’s motives, but more confident of academic integrity, they may conclude that the industry is guilty of misrepresentation and therefore recommend modification of the exemption to exclude certain categories of piezoelectric use. At best, this will accelerate both the uptake of lead-free materials and alternative, non-piezoelectric technologies, but at the expense of loss of performance and at significant cost to the end users. At worst, it could result in a loss of products of high socioeconomic value (e.g., medical ultrasound) from the marketplace and create job losses and adverse impacts in a number of local economies in the developed world. These factors should be tensioned against potential reductions in risks due to e-waste landfill and informal recycling whose real impact on environment and health should be assessed quantitatively (and which may be negligible given the dramatic reductions in lead that have already occurred in the e-waste stream due to the decreased utilization of lead solder). However, that balance will not be debated by the Expert Group; their brief is to review exemptions, with the goal of achieving maximum compliance with the existing RoHS directive, not to question the relevance and scope of RoHS 20 years after its introduction.

Whatever the recommendation of the Expert Group, those affected by it should be convinced that the decisions were reached in the light of accurate information, free from bias in industrial arguments and possible distortions of hyperbole and misapprehension. It is our public duty as scientists to ensure that this is always the case. Decisions of public interest may be made on the basis of our publications without our prior knowledge. Even the lowest level of habitual hyperbole that has become the norm to self-validate our work may not be without wider consequence and may contribute to the continued erosion of public trust in publicly funded science.



  1. 1.
    Britain has had enough of experts, says Gove (2016) Financial Times, June 3, 2016.
  2. 2.
    Directive 2002/95/EC of the European Parliament and of the Council of 27 January 2003 on the restriction of the use of certain hazardous substances in electrical and electronic equipment, Official Journal L 037, 13/02/2003 P. 0019–0023. (see also
  3. 3.
    Baldé CP, Forti V, Gray V, Kuehr R, Stegmann P. The global e-waste monitor—2017, United Nations University (UNU), International Telecommunication Union (ITU) and International Solid Waste Association (ISWA), Bonn/Geneva/ViennaGoogle Scholar
  4. 4.
    Data for 2018 obtained through Web of ScienceGoogle Scholar
  5. 5.
    Ibn-Mohammed T, Koh SCL, Reaney IM, Acquaye A, Wang D, Taylor S, Genovese A (2016) Integrated hybrid life cycle assessment and supply chain environmental profile evaluations of lead-based (lead zirconate titanate) versus lead-free (potassium sodium niobate) piezoelectric ceramics. Energy Environ Sci 9:3495–3520CrossRefGoogle Scholar
  6. 6.
    Koruza J, Bell AJ, Frömling T, Webber KG, Wang K, Rödel J (2018) Requirements for the transfer of lead-free piezoceramics into application. J Materiomics 4(1):13–26CrossRefGoogle Scholar

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© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.School of Chemical and Process EngineeringUniversity of LeedsLeedsUK
  2. 2.Group for Ferroelectrics and Functional OxidesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland

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