These are exciting times for materials science—a field which is growing more rapidly than any other physical science discipline. More than ever, the field is providing the vital link between science and engineering, between pure and applied. But what is the subject's definition and why is the field ballooning? I address these questions in the context of how APL Materials intends to play a role in advancing this important field. My introspective focus arises as we approach the first year anniversary of APL Materials.
First, what is materials science? As we all know, it is a very interdisciplinary field. But does this mean that anyone working on the science of a particular material is a materials scientist? The simple answer is “no.” As stated above, materials science is neither wholly pure nor wholly applied. At its heart, it is man's desire to fashion materials in the environment around him to improve his quality of life. For many, the definition is the science of linking structure, processing, and properties of materials. But this is really only in the teaching arena. In my view, in the research arena the subject has morphed over the last decade into something a little broader: Applied Science of Materials with Technology as the Driver. Fig. 1 shows how this is in a visual way.
Not all materials science researchers sit on the middle of the arrow—some may be found at the root of the arrow, and others at the tip. Others, such as myself, oscillate between the left and right, depending on the research project at hand. There is definitely a broad range, and a wide need, for materials science research of different emphasis.
This leads me to the second question: Why is the field ballooning?
Well, before I answer that, it is important to first acknowledge that man's steady technological progress over thousands of years has been interspersed with quantum leaps sparked by great discoveries: materials, and our ability to make them into useful forms, have played a central role in many of these discoveries. Neither the bronze age, the iron age, nor the silicon age would have taken place without great advances in materials science.
Up to the industrial revolution in the 19th century, itself enabled by great advances in the processing of iron, we were concerned only with using materials of a structural nature. The early 19th century, on the other hand, opened a new door to the functional arena which exploits the properties of electrons. It is true that some functional effects came about earlier, for example nano-plasmonic light interactions in Roman glass and in cathedral windows, but these were, in the main, unintended.
Perhaps the earliest example of functional materials was the light generation by the passage of electrons through a resistive metallic wire. Smaller scale, delicate electronic functional applications emerged in the middle of the 20th century, in the form of transistors based on silicon; the basis of today's digital age. The ability to create perfect, and chemically modified silicon was a truly great materials advance.
The functional arena relies on materials in just the same way as the structural arena does, but dimensions are more critical here—the smaller the better is the order of the day. It is very interesting to contemplate that while additional complexity in terms of combining large numbers of elements can lead to fascinating properties, e.g., with high temperature superconductors, it is not a pre-requisite since silicon and graphene are single element materials with, respectively, demonstrated and promised extreme impact.
As the 20th century has progressed, the greater ability to control materials by the use of sophisticated machines and chemicals (e.g., using lasers, vacuums, precision machining, complex organic chemicals, and biomolecules, etc.) has enabled a plethora of new materials forms (particularly very small ones) with remarkable properties. The realization of such amazing properties, together with the strong force of materialism and all that goes with it, – in particular our addiction to electronic gadgets and to travel and the associated energy burdens–, means that we need not just more materials but ever increasingly sophisticated ones.
Quite simply, materialism has contributed strongly to the growth of materials science. Opposing the force for more materialism is the urgent need to slow down climate change, further adding to the shopping list of sophisticated materials which are needed for clean energy through new generation, transmission, and storage systems. Hence, the more we exploit nature, the more we need to create better materials to sort out the problems we have created in this process. So it is no wonder that the field is escalating. Beyond electronics and energy, there is also a growing use of sophisticated materials in healthcare (e.g., drug delivery, cancer detection, molecular filtration, etc.), and this is further swelling the expanding balloon.
Henceforth, we need to follow the steps that nature has taken in its evolutionary journey: for example, in the combination of organic and inorganic materials, the creation of self-assembled structures over biomolecular length scales, and finally in designing materials that interact with one another in a smart way.
The use of biology to create and manipulate materials is likely to be very significant in this century. But our lives will likely also be influenced strongly by other materials lurking in the wings, for example, complex combinations of materials for new kind of solar cells, and complex, 1D or 2D materials with completely new electronic properties. It is not possible to predict which materials system could catalyse the next step-change improvement in our everyday lives. Graphene may do that, but other highly chemically complex materials will likely also play a role. The only thing for sure is that a sustainable future depends critically on new materials of different dimensionalities, easily manufactured without a large cost to the environment. The challenges facing the materials scientist are immense, and there will be no slowing of this field in the decades to come and beyond.
APL Materials aims to be leading open access journal in the field to bring the top papers in frontier materials science solutions to the technological challenges we face now and in the future. The first year of the journal has been extremely successful and its second year is looking to be even more so. I am both surprised and delighted by the broad range and quality of functional materials papers we have received and published so far. The video editorial which accompanies this editorial discusses the progress of the journal to date, the upcoming special issues for late 2014, and a discussion of very hot topic in science these days, research impact! http://youtu.be/611IZeFQAqA.