Nanomaterials Science

The research concerning nanomaterials has emphasized enormous scientific efforts in both fields of fundamental research and applied science. Fundamental research requires very pure materials to model the phenomena, on the other hand, applications necessitates complex formulations to optimize the peculiar property of the material. In both respects, processes for obtaining fine powders to make bulk ceramic, coating, films and composites are key points.

The most commonly used method is the so-called solid-state reaction or ceramic way. It involves intimate mechanical mixing of oxides, carbonates, nitrates… repeated grinding and heating cycles to achieve complete reaction between all reagents. However, besides its simplicity, this technique has clear disadvantages because it provides large grain size (1-10µm) and requires multiple repetitions of prolonged thermal treatment and grinding. As a consequence, uncontrolled crystalline growth might occur which provoke chemical and grain size non-uniformity.

Wet chemistry, often called "chemical way", can overcome many of these disadvantages. It is expected to increase the homogeneity of the product because mixing reagents is made at the molecular level, in solution. The resulting nanopowders have a high specific surface area and, consequently, have a high reactivity that decreases the final temperature treatment and time of synthesis.

Also, those materials showed enhanced features such as electrochemical properties in the field of electrochemical cells and gas sensors. Different chemical ways exist to form nanopowders such as co-precipitation, spray drying, freeze drying, sol-gel... Unfortunately these methods are time consuming and large quantities of nanopowders are hard to be obtained. Moreover, reaching high homogeneity for complex compositions (involving a large number of cations) might become very difficult owing to the generally different chemical behavior of each cation.

In Pirelli Labs we have optimized methods for nanomaterials synthesis in a broad range of high impact electro-ceramic oxides (superconductors, ionic / mixed conductors, semiconductors, dielectric and ferroelectric ceramics). Those processes become a fast, cheap, reproducible and easily scaling up chemical way for obtaining nanopowders.