Full Length ArticleIntense red-green up-conversion emission and their mechanisms of SrO: Er3+/Yb3+, Gd3+, Lu3+, Bi3+

A novel series of intense red-green up-conversion (UC) phosphors SrO: Er3+/Yb3+, Gd3+, Lu3+, Bi3+ were obtained through a modified solid-state reaction. The obtained UC samples emitted dazzling red-green light. Their spectra were composed of strong red emission (4F9/2→4I15/2) and green emission (2H11/2, 4S3/2→4I15/2) with the excitation of a 980 nm near-infrared (NIR) laser diode (less than 90 mW/cm2). The dependence of UC spectra on dopant contents, concentration and pumping power were comprehensively analyzed. The possible UC mechanisms and processes were proposed. These studies provided an opportunity to adjust emission colors and design new types of materials with desired properties through referencing a given methodology. It is anticipated that these materials may have potential applications in the fields of authentication, display and photo-switching.