Mohamed Abdelhedi

Spectroscopic properties of Eu3+ doped RbLaP4O12 powders.

Monophasic RbLaP4O12 possessing monoclinic symmetry with varied Eu(3+) concentrations was synthesized by flux method. The obtained cyclotetraphosphate exhibits very small crystals and the dopant Eu(3+) ions were successfully incorporated into the sites of La(3+) ions of the host lattice. These compounds were characterized by infrared and Raman spectroscopy, X-ray diffraction (XRD) and luminescence spectroscopy. The spectroscopy properties confirm the potentiality of present RbLaP4O12 doped with Eu(3+) ions as luminophore host materials to produce an intense red luminescence at 616 nm corresponding to (5)D0→(7)F2 emission level and have significant importance in the development of emission optical systems.

The solid solution Na0.39(NH4)1.61SO4·Te(OH)6

The title compound, sodium ammonium sulfate–telluric acid (1/1), Na0.39(NH4)1.61SO4·Te(OH)6, is isostructural with other solid solutions in the series M 1−x(NH4)xSO4·Te(OH)6, where ammonium is partially replaced with an alkali metal (M = K, Rb or Cs). The structure is composed of planes of Te(OH)6 octahedra alternating with planes of SO4 tetrahedra. The Na+/NH4 + cations are statistically distributed over the same position and are located between the planes. The structure is stabilized by O—H⋯O and N—H⋯O hydrogen bonds between the telluric acid adducts and the O atoms of sulfate groups, and between the ammonium cations and O atoms, respectively. Both Te atoms lie on centres of symmetry.