Kazuki Yoshimura, Group Leader of the Energy Control Thin Film Group of the Materials Research Institute for Sustainable Development (Director: Mamoru Nakamura), a part of the National Institute of Advance Industrial Science and Technology (President: Hiroyuki Yoshikawa) (hereinafter referred to as AIST) has, in collaboration with Shanhu Bao (Post-Doctoral Research Scientist at AIST), developed a new thin film material for a switchable mirror that can be switched between reflective and transparent states.
Previous research works have focused on the use of thin films made of magnesium-nickel alloy that behave as switchable mirrors: these, however, all have a yellow tinge in their transparent state. This is an obstacle to the practical application of such products, because such a yellow color renders the materials unsuitable for use in windows for buildings or automobiles.The newly developed switchable thin film is made of an alloy of magnesium and titanium: this was successfully produced as a uniform layer on sheets of glass with the size of 60 × 70 cm and we confirmed that it showed switchable behavior (Figures 1 and 2). The switchable mirror consists of two layers of glass enclosing a cavity and coated on their interior surfaces with the alloy film. A gas that contains hydrogen at a low concentration of about 1% or oxygen at a concentration of about 20% is introduced to the cavity to activate the switching behavior.