Functional Materials and Advanced Manufacturing

52 Functional and Smart Materials

the transfer in the amorphous phase. Next, we heat this lament by using the concept of

Joule-heating so that it can be converted in the form of thin lms [23]. For the proper

thermal evaporation, the preliminary materials are converted in the form of ingots or

powders before mounting them in a specially designed sample boat. The Joule-heating

causes the melting followed by thermal evaporation of the sample in the chamber hav-

ing vacuum at around 10

–6

Torr (~ 10

–4

Pa). To attain such a high vacuum, a combination

of a rotatory and an oil-diffusion pump is employed along with a liquid-nitrogen-cooled

trap. In most of the coating units, the electrical heating (i.e., Joule-heating) is performed ...