Phase-pure samples of sodium rare-earth phosphate tungstates Na2RE(PO4)(WO4) (RE = Y, Dy–Lu) and Na2Y(PO4)(WO4):Ln3+ (Ln = Eu, Tb) were obtained by reaction of the respective rare-earth oxide with ammonium hydrogen phosphate with sodium tungstate Na2WO4·2H2O as a flux at 1220 K. According to X-ray single-crystal investigations Na2RE(PO4)(WO4) (RE = Y, Tb–Lu) crystallise orthorhombically in space group Ibca (no. 73) (RE = Y, Z = 8, a = 1799.7(4), b = 1210.2(2), c = 683.82(14) pm, wR2 = 0.040, R1 = 0.037, 661 reflections, 62 parameters). The crystal structure contains non-condensed phosphate and tungstate tetrahedra with the (3 + 3)-coordinate sodium and eight-coordinate rare-earth ions in the voids. Relevant absorption and infrared spectra as well as the fluorescence spectra of Na2Y(PO4)(WO4):Ln3+ (Ln = Eu, Tb) are presented. An FP-LAPW band-structure calculation confirms the assignment of the main absorption as well as the optical band-gap (εcalc = 5.1 eV; εmeas = 5.2(1) eV) of Na2Y(PO4)(WO4).
You have access to this article
Please wait while we load your content...
Something went wrong. Try again?