Editing Smart glass (section)

==Related areas of technology==
{{More citations needed|date=February 2019}}

The expression '''smart glass''' can be interpreted in a wider sense to include also glazings that change light transmission properties in response to an environmental signal such as light or temperature.

* Different types of glazing can show a variety of [[chromism|chromic phenomena]], that is, based on [[photochemistry|photochemical]] effects the glazing changes its light transmission properties in response to an environmental signal such as light ([[photochromism]]), temperature ([[thermochromism]]), or voltage ([[electrochromism]]).<ref name=":1">{{Cite book |last=Bamfield |first=P. |url=https://www.worldcat.org/oclc/642685904 |title=Chromic phenomena : technological applications of colour chemistry |date=2010 |publisher=Royal Society of Chemistry |others=Michael G. Hutchings |isbn=978-1-84973-103-4 |edition=2nd |location=Cambridge |oclc=642685904}}</ref>
* Liquid crystals, when they are in a [[thermotropic]] state, can change light transmission properties in response to temperature. However, high temperatures are required to change the properties of liquid crystals and thermotropic liquid crystal compounds can be difficult to synthesize without blocking some wavelengths of the visible colour spectrum.<ref name=":1" />
* Various metals have been investigated. Thin Mg-Ni films have low visible transmittance and are reflective. When they are exposed to H<sub>2</sub> gas or reduced by an alkaline electrolyte, they become transparent. This transition is attributed to the formation of [[magnesium nickel hydride]], Mg<sub>2</sub>NiH<sub>4</sub>. Films were created by co sputtering from separate targets of Ni and Mg to facilitate variations in composition. Single-target d.c. magnetron sputtering could be used eventually which would be relatively simple compared to deposition of electrochromic oxides, making them more affordable. The [[Lawrence Berkeley National Laboratory]] determined that new transition metals were cheaper and less reactive, but contained the same qualities, thus further reducing the cost.
* Tungsten-doped [[vanadium dioxide]] ({{chem|VO|2}}) coating reflects infrared light when the temperature rises over {{cvt|29|°C}}, to block out sunlight transmission through windows at high ambient temperatures. Vanadium dioxide undergoes a semiconductor-to-metal transition at a relatively low temperature. This transition changes the material from have conducting properties to insulating properties and ends up changing the color of the glass as well as its transmission properties. Once the coating undergoes this change, it can effectively keep what it is insulating from gaining heat through filtering out the infrared spectrum.<ref name="Parkin">{{cite journal |last1=Parkin |first1=Ivan P. |last2=Manning |first2=Troy D. |title=Intelligent Thermochromic Windows |journal=Journal of Chemical Education |date=March 2006 |volume=83 |issue=3 |pages=393 |doi=10.1021/ed083p393 }}</ref>

These types of glazings cannot be controlled manually. In contrast, all electrically switched smart windows can be made to automatically adapt their light transmission properties in response to temperature or brightness by integration with a thermometer or [[photodetector|photosensor]], respectively.