Structure determination and optical properties of CsSm(PO3)4

A new alkali metal-rare earth polyphosphate CsSm(PO3)4 has been synthesized by flux method. The obtained compound has been characterized by means of single crystal X-ray diffraction, Fourier transform infrared (FTIR) and Raman scattering spectroscopies. It crystallizes in the monoclinic space group P21/n with the following unit-cell parameters: a = 10.382(2), b = 8.978(6), c = 11.205(4) Å, β = 106.398(3)° and Z = 4. The structure of CsSm(PO3)4 is an infinite three-dimensional framework made up of double spiral (PO3)n chains linked with neighboring SmO8 and CsO11 polyhedra. Spectroscopic properties of Sm3+ in this new compound including excitation, emission, and kinetic measurement have been performed. The emission spectrum shows four transitions characteristics of Sm3+ in the orange–red region by excitation wavelength at 400 nm. The decay time curve of 4G5/2 → 6H7/2 transition has been also registered and fitted to a single exponential function.