Low-Temperature Synthesis and Luminescent Properties of Lanthanum Metaphosphate LaP3O9 : Tb

Terbium-doped lanthanum metaphosphates La1–хTbхP3O9 (х = 0.05, 0.1, 0.2, 0.3, 0.4), promising as inorganic luminophors have been prepared by extraction–pyrolytic method at lower temperature as compared with the known methods. Crystal structure and optical properties of obtained samples have been studied by X-ray powder diffraction, IR and luminescence spectroscopy; unit cell parameters have been calculated. Compounds with rhombic structure (space group C2221) have been obtained in the temperature range of 500–900°С. All unit cell parameters linearly decrease on introduction of terbium in lanthanum metaphosphate. Compounds La1–хTbхP3O9 exhibit strong luminescence in the region of 450–650 nm. A sample of La0.8Tb0.2P3O9 prepared over 1–h annealing at 900°C displays the maximal luminescence intensity.