Chiang Mai Journal of Science

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Take a look at everyday life and we find ourselves surrounded by man-made materials: metals, glass, paper, plastics.  We even have manmade materials inside us: fillings in our teeth, artificial lenses in our eyes, artificial hip joints, synthetic heart valves, etc., all of which are man-made from materials designed to survive and function within the human body.  In outer space, we have man-made satellites orbiting the earth and spacecraft traveling towards distant planets.  However, perhaps the most important of all are the electronic products which have become such an essential part of  our everyday lives as well as being necessary devices for industry.  These products include such household and office appliances as radios, televisions, mobile telephones and computers.  As a consequence, the electronics industry is now a large-scale industry displaying very large growth rates in the world markets.  Furthermore, electronic parts are becoming ever smaller (hence the term “microelec-tronics”), thereby reducing their transportation costs.  These electronic parts, commonly termed “electronic ceramics” (or “fine ceramics”), can be pro-duced by mixing appropriate ratios of (by definition) “solid inorganic nonmetal materials followed by firing”.  Today’s electronic ceramics are a new breed of material, attracting attention over a wide range of applications.  While “classical” or “traditional” ceramics (pot-teries) are made of   natural materials, electronic ceramics are made by combining together the atomic compositions of  various, refined elements through scientific forming and sintering processes.  In other words, electronic ceramics are made by scientifically controlling chemical compositions, resulting in new materials customized to the unlimited amount of purposes they serve.
You may be asking: aren’t electronic ceramics essentially the same as classical ceramics and, if not, what is the difference? Well, there is a vast difference!  The secret of electronic ceramics and their characteristic properties lies in their unique microstructure. They consist of  finely-aggregated grains  resembling, in a way, a stone wall with each piece fitting neatly into place relative to the next.  Classical ceramics, on the other hand, are much more porous and irregular.
In today’s electronic ceramics, the grains, grain boundaries and surface layers are all processcontrolled and exhibit specific responses towards applied electrical or environmental changes. In today’s modern society, these specific responses are utilized for specific purposes. For instance, capacitors using titanium oxide or barium titanate ceramics are polarized when a voltage is applied to them.  In contrast, other types of ceramics containing different additives, though mainly composed of  the same barium titanate, serve as unique semiconductors which can turn electric flow on and off  under given conditions.  This is a result of the electrical charges in their grain boundaries.  The function of  electronic ceramics therefore varies according to their internal microstructure.
At this point, one may also ask: what is the difference between physics and materials research?  Actually, they are very closely related.  If  we try to distinguish between their interests, we can perhaps see the difference more clearly.  Materials research focuses its attention on the grain boundaries and grain sizes (as is meant by the term “microstructure”) in the 10-6  m (1000 nm) region (even going down to 100 nm) since the electrical effects mainly occur at the grain boundaries.  Physicists, on the other hand, study the effects of the ions in the molecules composing the compounds in the nanometer (nm) region and below.  Nevertheless, materials research and physics are closely aligned and their researchers invariably work closely together.
Long before these electronic parts reached the manufacturing stage in industry, research work had been in progress for several decades.  This research work involved many branches of  basic science such as physics, chemistry and mathematics.  Ceramics can be synthesized either by solid-state sintering (mixed oxide route) or via a chemical route. Many methods have been employed in the chemical route such as co-precipitation, oxalate, and sol-gel techniques.  After obtaining the appropriate powder and ceramics by proper heat treatment, they are then characterized and their physical and chemical properties measured.  Understanding their properties and their microstructure-property relationships is a vital part of the research and involves theoretical scientists as well. For example, the crystal structures of  compounds require elucidation, often with the aid of computer modeling, not only for characterization purposes but also in order to predict the outcome of further processing steps. But where do the pure inorganic powders or solutions come from which are used in making electronic ceramics?  The answer is that they are the products from purification of minerals which are deposited all around the world.  For this reason, we need to bring geologists and chemists into the fray if we are to produce the highly pure chemical powders needed for electronic ceramics processing.  Thus, the field of  electronic ceramics is a good example of how different branches of basic science are now being brought together in interdisciplinary research. In this way, we can confidently expect to continue producing new materials for the future and, in doing so, improve the quality of  our everyday lives.

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