Editing Titanium dioxide (section)

===Thin films===
When deposited as a [[thin film]], its refractive index and colour make it an excellent reflective optical coating for [[dielectric mirror]]s; it is also used in generating decorative thin films such as found in "mystic fire topaz".{{citation needed|date=December 2024}}

Some grades of modified titanium based pigments as used in sparkly paints, plastics, finishes and cosmetics – these are man-made pigments whose particles have two or more layers of various oxides – often titanium dioxide, [[iron oxide]] or [[alumina]] – in order to have glittering, [[iridescent]] and or [[pearlescent]] effects similar to crushed [[mica]] or [[guanine]]-based products. In addition to these effects a limited colour change is possible in certain formulations depending on how and at which angle the finished product is illuminated and the thickness of the oxide layer in the pigment particle; one or more colours appear by reflection while the other tones appear due to interference of the transparent titanium dioxide layers.<ref>{{cite book|author=Koleske, J. V. |title=Paint and Coating Testing Manual|url=https://books.google.com/books?id=ri6FkY2xvgcC&pg=PA232|year=1995|publisher=ASTM International|isbn=978-0-8031-2060-0|page=232}}</ref> In some products, the layer of titanium dioxide is grown in conjunction with iron oxide by calcination of titanium salts (sulfates, chlorates) around 800&nbsp;°C<ref>{{cite book|author=Koleske, J. V. |title=Paint and Coating Testing Manual|url=https://books.google.com/books?id=ri6FkY2xvgcC&pg=PA229|year=1995|publisher=ASTM International|isbn=978-0-8031-2060-0|page=229}}</ref> One example of a pearlescent pigment is Iriodin, based on mica coated with titanium dioxide or iron (III) oxide.<ref>{{citation |url= http://pearl-effect.com/index.php?option=com_content&view=article&id=92&Itemid=62 |archive-url= https://web.archive.org/web/20120117030508/http://pearl-effect.com/index.php?option=com_content&view=article&id=92&Itemid=62 |archive-date= 17 January 2012 |title= Pearlescence with Iriodin |work= pearl-effect.com}}</ref>

The iridescent effect in these titanium oxide particles is unlike the opaque effect obtained with usual ground titanium oxide pigment obtained by mining, in which case only a certain diameter of the particle is considered and the effect is due only to scattering.