BN-coated Ca_1−xSr_xS:Eu solid-solution nanowires with tunable red light emission

Abstract

We report on the controlled growth of novel BN-coated Ca(1-x)Sr(x)S:Eu nanowires via a solid-liquid-solid process. The Ca(1-x)Sr(x)S solid solution forms as one-dimensional nanowires and has been coated with homogeneous protective BN nanolayers. The structure and luminescence properties of this new nanocomposite have been systematically investigated. High-spatial-resolution cathodoluminescence investigations reveal that effective red color tuning has been achieved by tailoring the composition of the Ca(1-x)Sr(x)S nanowires. Moreover, codoping of Ce(3+) and Eu(2+) in the CaS nanowire can induce energy transfer in the matrix and make it possible to obtain enhanced orange color in the nanowires. The BN-coated Ca(1-x)Sr(x)S:Eu solid-solution nanowires are envisaged to be valuable red-emitting nanophosphors and useful in advanced nanodevices and white LEDs.

Tuning of Emission Wavelength of CaS:Eu by Addition of Oxygen Using Atomic Layer Deposition

“…In comparison to the CaS:Eu phosphor, CaS:EuO reveals a red peak emission towards shorter wavelengths. Similar tuning effects of the CaS:Eu emission has been previously reported by adding alkaline earth metals such as strontium [25,26], magnesium and barium to the reaction mixture [27]. However, we present a study where the tuning is performed by adding oxygen anions reinforcing the idea that ALD can be used to modify the vicinity of the dopant elements.…”

“…The larger lattice constant may indicate that the distance between Eu 2+ cations and the anions increase. The larger distance between Eu 2+ cations and the anions lead to a decrease in the crystal-field strength [25,26]. Therefore, the addition of a O 2− ion originates a decrease in the energy difference between t 2g and the E g states of the 4f 6 5d 1 electronic configuration, thus leading to blue-shifted emission.…”

Local defect-induced red-shift of cathodoluminescence in individual ZnS nanobelts

“…18 In order to precisely determine the spatial luminescence regions responsible for the NBE and broad visible emission, high-resolution CL monochromatic imaging was carried out. 23,24 Fig. 2b shows a flat ZnS nanobelt with a smooth surface and its corresponding CL images recorded at 344 nm and 527 nm are also presented in Fig.…”

A red phosphor BaTiF6:Mn4+: reaction mechanism, microstructures, optical properties, and applications for white LEDs

“…However, the poor chemical stability of sulfides and critical synthetic requirements of air-sensitive metal nitrides make them unfavorable candidates for competitive products. 5,[15][16][17] Mn 4+ doped red phosphors have received increasing attention due to their broad absorption band in the 380-490 nm region and sharp emission peaks at 610-760 nm. [18][19][20][21][22][23][24][25][26] Among them, Mn 4+ doped dialkali hexafluorometallates in the form of A 2 XF 6 :Mn 4+ (A = K, Na, and Cs; X = Si, Ge, Zr, and Ti) are especially attractive due to their maximum absorption band in the blue region (that matches well with the electroluminescence of InGaN chips) and sharp emission peaks in the red region (that possess high color purity), which shows significant potential for their application in WLEDs.…”