Spectral comparison of MgSO4 doped with Dy, Mn, P, and Cu

Abstract

Phosphor emission spectra are presented for MgSO4 doped with Dy,MgSO4 co-doped with Dy and Mn, MgSO4 co-doped with Dy and P, and MgSO4co-doped with Dy, P and Cu. All spectral wavelengths are related totransitions in Dy3+ ions. In a broad wavelength band around ~660 nm, threedimensional glow curves at ~140 and ~190 °C in the MgSO4:Mn spectrum aredue to emissions from Mn2+ ions. For MgSO4 co-doped with Dy and Mn the mainglow peak occurs at ~380 °C, about 20 °C above the fourth glow peak obtainedin MgSO4 doped with Dy. The emission spectra of the MgSO4:Dy, Mn phosphor showthe competitive de-excitation processes between Dy3+ and Mn2+ ions. Thisindicates that rare earth and Mn ions in MgSO4:Dy, Mn form complex defects thatdominate the traps and recombinations. The MgSO4:Dy glow peak at around 260 °Cshifts in MgSO4:Dy, P to ~280 °C with enhanced intensity, while the ~360 °Cglow peak remains in place with a slightly increased intensity. The enhancedthermoluminescence (TL) sensitivity obtained by co-doping with P is probably due to chargecompensation. The relative intensities vary between the 480 and 580 nmband of the glow peaks while the temperature (~280 °C) is unchanged for MgSO4co-doped with Dy, P and Cu. The Cu+2 or Cu+1 ions act as charge compensators tothe Dy3+ ions and reduce the concentration of Mg2+ vacancies in MgSO4:Dy, P, Cu.This results in changes to the dose response characteristics.