Structural and luminescene properties of magnesium strontium metaphosphat e doped with europium and dysprosium ions

Abstract

A series of samples based on xMgO-(50-x)SrO-50P2Os (with 0 < x <50 mol %) were prepared using solid state reaction method and sintered at 900°C. The crystalline phase of powder samples were characterized using X-ray diffraction (XRD) while the assignments of the vibration modes were determined using Fourier Transform Infrared (IR) and Raman spectroscopies. The XRD analysis indicated that the prepared samples were polycrystalline phase of Sr(PO3)2, SrMgP2O7, Mg2P4O12 and Mg2P2O7. The optimum sintering temperature of the prepared samples is 900oC. The Infrared and Raman studies showed that the magnesium strontium metaphosphate system consists of a main network of Q2, Q1 and Q° tetrahedral units. There were four peaks observed in the both spectra which are P=O group (1320 cm-1), PO2 group (1200 - 1170 cm-1), PO3 and PO4 groups (1160 - 950 cm-1) and P-O-P group (950 - 704 cm-1). This study illustrated that SrO and MgO act as modifiers and also improved chemical and physical stability of the phosphate material. The dopant ions (Eu3+ and Dy3+) as studied using XRD, IR and Raman spectra showed that small quantities of europium and dysprosium ions does not affect the local structure of magnesium strontium metaphosphate network. The luminescence property of the Eu3+ and Dy3+ as dopants in magnesium strontium metaphosphate was studied using photoluminescence spectroscopy. The emission peaks for Eu3+ doped sample were located at 568 nm, 582 nm, 605 nm, 642 nm and 689 nm, due to the 5D0 —^ 7Fj (j = 0, 1, 2, 3, 4) transition. Meanwhile for Dy3+ doped sample, two intense peaks appear at 477 nm and 564 nm are due to the 4F9/2 — 6H15/2 and 4F9/2 — 6H13/2 transitions. For sample doped with Eu3+ and Dy3+, the intensity of the main peak increases. This study also showed that magnesium strontium metaphosphate doped with Eu3+ and Dy3+ has better luminescence characteristic as compared to strontium metaphosphate or magnesium metaphosphate. The results of the study suggested that magnesium strontium metaphosphate is a potential candidate for plasma display applications.