Preparation and Application of New Amorphous Materials in Non-chalcogenide System

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Two new photosensitive amorphous materials were found in non- chalcogenide systems; dopant-free calcium aluminate glasses and amorphous red phosphorus.Binary calcium aluminate glasses show two types of photosensitivities with different nature to ultravioletradiation, stable coloring( bleachable by heating tip to 200ﾟC) and photochromism. No doping of optically active components such as Au, Ag or halogens is required for the appearance, which is totally differs from photosensitive glasses so far. These insensitivities can be imparted to calcium aluminate glasses with the same chemical compositions by only changing the melting atmosphere such as oxidizing or reducing. These sensitivities were attributed to the presence of oxygen-related point defects (oxygen-excess type or oxygen vacancy) in the glasses.Amorphous red phosphorus films were successfully prepared by rf sputtering method. These films were found to show three photoinduced phenomena, photodarkening, and photodoping of silver.These observation is the fist report in non-chacogenide systems.Further, photobleaching was found, which has been not observed in chacogenide systems so far. The results were explained by that the top of the valence band is composed of p sigina orbital,i.e.band gap illumination dissociates P-P bonds. The resulting P_2 molecule or P radicals rearrange or react with oxygen molecule, depending on the atmosphere. No such a photo-induced bond dissociation is observed because the lone pair orbitals occupy the top of the valence band in chacogenides.