High-Pressure Investigations of Yttrium(III) Oxoarsenate(V): Crystal Structure and Luminescence Properties of Eu3+-Doped Scheelite-Type Y[AsO4] from Xenotime-Type Precursors

Publication date: Available online 7 March 2018 Source:Journal of Solid State Chemistry Author(s): Florian Ledderboge, Jan Nowak, Hans-Joachim Massonne, Katharina Förg, Henning A. Höppe, Thomas Schleid Colourless, water- and air-stable single crystals of yttrium(III) oxoarsenate(V) Y[AsO4] in the xenotime-type crystal structure were prepared by the reaction of yttrium sesquioxide (Y2O3) dissolved in aqueous nitric acid (13%) with a solution of arsenic(V) oxide hydrate (As2O5 ∙ 3 H2O) and subsequent neutralization with 1M caustic soda. Y[AsO4] crystallizes tetragonally in the space group I41/amd with the lattice parameters a = 704.63(6) and c = 628.94(5) pm for Z = 4 and is isotypic to the minerals xenotime RE[PO4] (RE: mainly Y and Yb) and chernovite RE[AsO4] (RE: mainly Y and Ce). This xenotime-type yttrium compound was used as precursor in a high-pressure experiment (20 kbar) at 700°C to create a new tetragonal modification of Y[AsO4]. It shows the scheelite-type structure (space group: I41/a) with the lattice parameters a = 498.23(4) and c = 1120.71(9) pm for Z = 4, named after the mineral scheelite (Ca[WO4]). Both tetragonal structures are characterized by only one crystallographically unique position for each of the Y3+, As5+ and O2– ions with distances of d(Y–O) = 232 and 241pm (C.N. = 8) as well as d(As–O) = 169pm (C.N. = 4) in the case of the scheelite-type structure. The xenotime-type compound shows an unexpected slight decrease in average bond len...

Source: Journal of Solid State Chemistry - March 9, 2018 Category: Chemistry Source Type: research