Pressure Dependence of Mn²⁺ Luminescence in Differently Sized ZnS:Mn Nanoparticles

Abstract

The pressure behavior of Mn2+ emission in the 10-, 4.5-, 3.5-, 3-, and 1-nm-sized ZnS:Mn2+ nanoparticles is investigated. The emission shifts to lower energies with increasing pressure, and the shift rate (the absolute value of the pressure coefficient) is larger in the ZnS:Mn2+ nanoparticles than in bulk. The pressure coefficient increases with the decrease in particle size with the 1-nm-sized particles as an exception. Pressure coefficient calculations based on the crystal field theory are in agreement with the experimental results. The pressure dependence of the emission intensity is also size dependent. For nanoparticles 1 and 3 nm in size, the luminescence intensity of Mn2+ decreases dramatically with increasing pressure, while, for bulk and particles with average sizes of 3.5, 4.5, and 10 nm, the luminescence intensity of Mn2+ is virtually unchanged at different pressures. The bandwidth increases faster with increasing pressure for smaller particles. This is perhaps due to the fact that there are more Mn2+ ions at the near-surface sites and because the phonon frequency is greater for smaller particles. These new phenomena provide some insight into the luminescence behavior of Mn2+ in ZnS:Mn2+ nanoparticles.

Synthesis and properties of transition metals and rare-earth metals doped ZnS nanoparticles

“…However, some other groups reported that the lifetime of Mn 2+ luminescence was in the millisecond range [34,49,86,87] while attributing the fast decay component in the nanosecond range to ZnS defect emission. Their results show that the nanosecond decay times reported for the Mn 2+ emission are most likely because the tail of broad defect related ZnS emission which overlaps with Mn 2+ emission at around 590 nm.…”

“…As the particle size reduced, the shift between the absorbing and emitting state increased. Su et al [86] studied the absorption (ABS) spectrum of the 3.5 nm ZnS:Mn 2+ particles sample, whose absorption edge is at 335 nm with an absorption peak at 310 nm which is about 30 nm blue-shift from the absorption of bulk ZnS:Mn 2+ at 342 nm as a result of quantum size confinement.…”

“…4. In addition, Su et al [86] reported that the emission shift to lower energies with increasing pressure and the shift rate (the absolute value of the pressure coefficient) is larger in the ZnS:Mn 2+ nanoparticles than in bulk one. They explained that the red-shift may come from the quantum confinement effect in nanoparticles, which leads to the charge of crystal field surrounding Mn 2+ ions.…”

“…In addition, some groups also [64,72] found out that there was an aging effect for ZnS:Mn 2+ colloids, the Mn 2+ ion luminescent intensity decreased after the colloids were kept at room temperature for a long time, because the surface modification deteriorated and nonradiative relaxation paths increased. Su et al [86] found out the luminescence intensity of Mn 2+ was weakly dependent on pressure, while, for particles 1 and 3 nm in ZnS:Mn 2+ size, the luminescence intensity of Mn 2+ was quenched dramatically at increasing pressure. All these results demonstrated that the rare-earth and transition metals in host nanocluster can yield more efficient phosphors.…”

Theoretical study of spin singlets contributions to zero-field splitting and local lattice structure of Cr2+ in CdGa2S4

“…Impurities in semiconductors have attracted a great deal of attention for many years owing to their significance for practical applications, as in photoconductors, microwave detectors, and electroluminescent devices [1][2][3][4][5][6][7][8]. Among the impurities, particular attention has been focused on the transition metal ions because they are commonly associated with deep levels within the host crystal band gap.…”