The photoluminescence enhancement of Mn2+ ions and the crystal field in ZnS:Mn nanoparticles covered by polyvinyl alcohol

Abstract

The polyvinyl alcohol (PVA)-capped ZnS:Mn nanoparticles with Mn content of 8 mol% and different PVA mass (denoted as ZnS:Mn/PVA) are synthesized by co-precipitation method, in which PVA solution is mixed from the beginning with the initial solutions used to synthesize ZnS:Mn nanoparticles. The microstructures, morphology and average crystalline size of ZnS:Mn/PVA nanoparticles were investigated by X-ray diffraction patterns, high resolution transmission electron microscopy, thermal gravimetric analysis (TGA) and differential thermal gravimetric analysis and Fourier transform infrared absorption spectra. The role of PVA to the photoluminescence (PL) of Mn 2? ions in these nanoparticles at 300 K were studied by the PL and photoluminescence excitation (PLE) spectra. The investigated results show that the PVA covering for ZnS:Mn nanoparticles almost is not change the microstructure, morphology, the crystal field and the peak positions in their PL and PLE spectra, but the maximum intensity of peaks increased with PVA mass from 0.2 to 1.0 g. The clear peak positions in PLE spectra show that the energy levels of Mn 2? ions were splitted into multiple levels in the ZnS:Mn crystal field, that its strength D q was caculated. Furthermore, the effect of PVA on the PL enhancement of Mn 2? ions in ZnS:Mn/PVA nanoparticles also was explained.

Impact of ZnS/Mn on the Structure, Optical, and Electric Properties of PVC Polymer

“…According to research conducted by Rasmagin et al, who investigated the optical characteristics of nano CdSe/ZnS in heat-treated PVC films, heating for a short period of time increases the photoluminescence intensity, while heating for a long period of time significantly decreases it [17]. Furthermore, Thai et al discovered that polyvinyl alcohol-coated ZnS:Mn nanoparticles increased both the photoluminescence and the crystal field of Mn 2+ ions [18]. The nonlinear optical (NLO) features were improved with an increase in the Mn:ZnS doping percentage in Mn: ZnS/PMMA polymer nanocomposites [19].…”

Probing into the conduction band and type of carriers/traps on red/orange persistent phosphors in vacancy & solid-solution induced (Sr/Ba)1−xCaxGe4−yO9:Mn2+

“…4(a) shows the excitation spectra of Ba 0.7 Ca 0.3 Ge 3.44 O 9 :0.01Mn 2+ and Sr 0.7 Ca 0.3 Ge 3.41 O 9 :0.01Mn 2+ , which has three excitation peaks between 250 nm and 450 nm. 27 Among them, the peak at 280 nm is the charge transition band (CTB) of Mn–O, the peak at 366 nm is attributed to 6 A 1 to 4 T 2 ( 4 D), and the one at 415 nm originates from the characteristic jump from 6 A 1 to 4 A 1 ( 4 G). According to the energy–wavelength conversion equation, 28 the energy corresponding to the CTB can be derived, i.e.…”

Energy transfer and luminescence enhancement of Cu2+ ions in polyvinyl pyrrolidone caped ZnS:Cu nanoparticles

“…However, during the synthesis of transition metal-doped ZnS nanoparticles, the dangling bonds and vacancies also appeared that called the surface states, creating non-radiative recombination centers on the surface of the nanoparticles, reducing PL intensity. In order to reduce the above effects, the nanoparticles need to be protected and isolated from their surroundings by surfactants such as thioglycolic (TGA), trioctyl phosphinoxide, sodium hexametaphosphate, and other polymers such as polyvinyl alcohol (PVA), [21][22][23] polyvinyl pyrrolidone (PVP). [24][25][26][27][28] The polymers have strongly polarized groups of carbonyl C=O and hydroxyl OH, so when the nanoparticles are coated by polymers [29][30][31][32][33][34] they will create coordination bonds between these polar groups and the Zn 2+ , Cu 2+ ions of ZnS:Cu nanoparticles.…”