Pressure dependence of the impurity-trapped exciton emission inBaF2:EuandBaxSr1−

Pressure and temperature dependence of the emission in BaF2:Eu and SrF2:Eu

“…The sample details were described in the papers [3,5]. Ambient pressure luminescence and luminescence excitation spectra were measured using a system consisting of a Xe lamp (1000 W), two monochromators SPM2 (one in the excitation and one in the detection line) and two photomultipliers (the first for the luminescence and the second for reference signal detection).…”

“…This absorption band is accompanied by luminescence related to a transition from the lowest state of the 4f 6 5d 1 electronic configuration to the ground state. In some cases mainly in sulfides [2], and fluorides [3] doped with Eu 2+ , the 4f 6 5d 1 (e) -4f 7 emission is replaced by the red-shifted anomalous luminescence. An extensive review of the anomalous luminescence effect in rare earth-doped materials has been done by Dorenbos [4].…”

“…In our former paper [3], we have shown that the pressure can induce a transition from anomalous to normal 4f 6 5d 1 (e)-4f 7 luminescence in BaF 2 and Ba 0.3 Sr 07 F 2 doped with Eu 2+ . It has been found that at 20 K, this transition occurs at about 30 kbar in BaF 2 and 40 kbar in Ba 0.3 Sr 0.7 F 2 .…”

“…In SrF 2 only the 4f 6 5d 1 (e)-4f 7 emission is observed at all measured pressures. The statistical model of Ba-Sr distribution in the crystals has been used for the analysis of the dependence of luminescence lineshape on the crystal content and pressure [3].…”

Preparation of Sr2Si5N8:Eu2+ for white light-emitting diodes by multi-step heat treatment

“…The broad band emission peak at 628 nm of the Sr 2 Si 5 N 8 :Eu 2+ (2 at.%) phosphor at the excitation of 455 nm is assigned to the allowed 4f 6 5d 1 → 4f 7 transition of Eu 2+ ion [15]. Due to the high covalent environment around Eu 2+ ion, emission of Sr 2 Si 5 N 8 :Eu 2+ phosphor was observed at a fairly longer wavelength region compared to MF 2 :Eu 2+ or M 2 SiO 4 :Eu 2+ (M = Sr/Ba) [19,20]. In the present study, the 2nd heat treated specimens contained lower impurities such as residual carbon and oxygen (Table 1).…”