Synthesis, Structures, and Luminescent Properties of Sodium Rare-Earth Metal(III) Chloride Oxotellurates(IV), Na2Ln3Cl3[TeO3]4 (Ln = Sm, Eu, Gd, Tb, Dy, and Ho)

Six sodium rare-earth metal(III) chloride oxotellurates(IV), Na(2)Ln(3)Cl(3)[TeO3](4), isostructural to Na2Y3Cl3[TeO3](4), were synthesized by flux techniques and characterized by single-crystal XRD. The compounds crystallize in the monoclinic space group C2/c with lattice constants a = 23.967(1), b = 5.6342(3), c = 16.952(1) angstrom, beta = 134.456(5)degrees for Ln = Sm, a = 23.932(2), b = 5.6044(5), c = 17.134(1) angstrom, beta = 135.151(6)degrees for Ln = Eu, a = 23.928(1), b = 5.5928(1), c = 17.1133(8) angstrom, beta = 135.366(3)degrees for Ln = Gd, a = 23.907(1), b = 5.569(3), c = 16.745(1) angstrom, beta = 134.205(3)degrees for Ln = Tb, a = 23.870(1), b = 5.547(3), c = 16.665(1) angstrom, beta = 134.102(3)degrees for Ln = Dy, and a = 23.814(1), b = 5.526(3), c = 16.626(1) angstrom, beta = 134.016(3)degrees for Ln = Ho and Z = 4. Their crystal structure can be considered as a framework built of intergrowing LnO and Na(O,Cl) slabs with channel walls decorated by tellurium atoms of [TeO3](2) groups. The luminescent properties of the new compounds due to the Ln(3+) cations are described and discussed. We also discuss the crystal chemistry of various alkali-metal rare-earth metal(III) halide oxochalcogenates(IV).