Thin films and nanostructured coatings for eco-efficient buildings - Nanotechnology in Eco-efficient Construction - page 179

specifi c pros and cons. These techniques allow the manufacturing of thin
coatings of virtually any material and material combination either as a
single layer or in a multilayer confi guration.
It should be noted that the techniques that have been described are best
suited for coating non-patterned surfaces. However, masking is possible in
order to produce desired patterns and, alternatively, etching or some other
subtractive technique can be used to obtain a certain confi guration. Rather
than obscuring or subtracting material, it is also possible to use an additive
process such as printing with an appropriate ink containing nanoparticles,
normally followed by heat treatment for some time to remove undesired
binder residues. Recent advances in printing technology, as well as the great
amount of contemporary work on large-scale fabrication of nanoparticles,
nanorods and 'nano-anything' - referred to briefl y in Section 8.2.4 - make
it probable that printing-related techniques will gain increased popularity
in the future.
As emphasized in Section 8.1, thin fi lms use little material to reach large
effects, and hence - generally speaking - the materials that can be employed
in thin fi lms are many more than those that can be used in the case of bulk-
like materials. Nevertheless, clearly the least common elements should be
avoided (Tao et al. , 2011). Plate III (between pages 162 and 163) gives an
overview of the elemental abundance and shows that elements such as
ruthenium, rhodium, tellurium, rhenium, osmium and iridium occur with a
mass fraction around 10 −9 or below (Berry, 2010). The data in the fi gure
should be regarded with some caution, though, and the fact that an element
is not rare does not make it cheap. One example may be indium oxide
(Schwarz-Schampera and Herzig, 2002), which is often the premier choice
for a transparent electrical conductor and is used in many modern informa-
tion and communication technologies as well as for energy-related applica-
tions. This element is normally obtained as a small byproduct in zinc refi ning,
which makes it much more costly than transparent conductors based on
zinc oxide or tin oxide.
The technologies for making thin fi lms and nanostructured coatings have
been undergoing rapid development at least since the 1950s. This develop-
ment still continues today, and does so at a stunning pace, and it is a safe
bet that thin fi lms and coating technologies will be of ever increasing impor-
tance as the burden on nature's resources becomes even more acute in the
future.

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8.5 References

Anders A (2010), 'A structure zone diagram including plasma-based deposition and
ion etching', Thin Solid Films , 518, 4087-4090.
Bach H and Krause D (eds) (2003), Thin Films on Glass , Springer, Berlin.