Research And Regulation Of Long Afterglow And Photocatalytic Properties Of Ga₂O₃:Cr³⁺

Long-persistent (LP) materials are a category of materials which can store energy like UV or visible light and emit after excitation light turned off. Recent years, imaging, diagnosis and detection of biological tissue by using near infrared-light (NIR) radiation has received more focus on it. Due to the special characteristics NIR-LP materials has attracted widely attention in making biomarkers. However, the research of NIR-LP materials is still in the initial stage. There is few activated ions can emit LP in the NIR region and the LP properties of them still need to improve. So it has an important realistic meaning that improving the properties of NIR-LP materials. In this thesis, a series of NIR-LP materials of gallium oxide co-doping with trivalent chromium ions has been synthesized via the high temperature solid-state reaction method. The influence of Ga2O3:Cr3+ by Zn2+, In3+ and Mg2+ substituting Ga3+ is discussed from phase structure, luminescence and LP properties, respectively. Moreover, the photocatalytic properties are analyzed and the relationship of LP and photocatalytic properties is discussed.Ga203:Cr3+0.01, Zn2+0.005 NIR-LP materials were synthesized via the high-temperature solid state reaction. The XRD pattern shows that Zn2+ co-doping has no effect on crystal structure of Ga2O3 and Zn2+ co-doping mainly substitute Ga3+ in Ga2O3. The fluorescence characteristics shows the emission comes from Cr3+ ions and a role of energy transfer exists in the sample that energy absorbed by host could be transferred to Cr3+ ions which is the emitting center. The decay of persistent luminescence is coincident with a carrier model. Zn2+ co-doping could enhance the afterglow brightness and prolong the duration time of afterglow. The test of photocatalytic performance indicates that the photocatalytic efficiency of the sample could be improved by Zn2+ co-doping.Gai.95In0.05O3:Cr3+0.01 NIR-LP materials were synthesized via the high-temperature solid state reaction. The XRD pattern shows that In3+ co-doping mainly substitute Ga3+ in Ga2O3. The fluorescence spectra of the samples shows that In3+ co-doping could depress the crystal field strength surrounding Cr3+ions and improve the 4T2â†'4A2 emission intensity. The decay of persistent luminescence is coincident with a carrier model. In3+ co-doping could enhance the afterglow brightness and prolong the duration time of afterglow. Moreover, the relationship of LP and photocatalytic properties is discussed.Ga1.99Mgo.oiO3:Cr3+o.oi NIR-LP materials were synthesized via the high-temperature solid state reaction. The XRD pattern shows that the un-equivalent substitution by Mg2+ ions mainly substitutes Ga3+ in Ga2O3 through different substitution amount. The fluorescence characteristics shows that Mg2+ co-doping could enhance the crystal field strength surrounding Cr3+ions and decrease the 4T2â†'4A2 emission intensity. The decay duration of persistent luminescence contends the double exponential decay and the hyperbolic decay simultaneously. Mg2+ co-doping could enhance the afterglow brightness and prolong the duration time of afterglow. Moreover, the sample shows the photostimulated properties by Mg2+ co-doping and the sample shows the best photostimulated properties by using 550nm stimulating. The photocatalytic properties are improved by Mg2+ ions co-doping. The relationship of photocatalytic properties, LP properties and relationship of LP and photostimulated properties is discussed.