Syntheses, structures, and properties of RbScFAsO4 and CsScFAsO4: Scandium-containing analogues of potassium titanyl phosphate (KTiOPO4)

The syntheses, single-crystal structures, and some properties of RbScFAsO4, and CsScFAsO4, the first scandium-containing analogues of potassium titany l phosphate (KTiOPO4), are reported. In both phases, the distinct cis and t rans ScO4F2 octahedra are essentially regular and lack the distinctive shor t Ti = O bonds seen in KTiOPO4. The powder second harmonic generation respo nses of these phases are much smaller that that of KTiOPO4. Crystal data: R bScFAsO4, M-r = 288.34, orthorhombic, space group Pna2(1) (no. 33), a = 13. 687(4) Angstrom, b = 6.804(2) Angstrom, c = 11.248(2) Angstrom, V = 1047.5( 5) Angstrom(3), Z = 8, R = 3.15%, R-w = 3.95% [1807 reflections with I > 2 sigma(1)]; CsScFAsO4, M-r = 335.78 orthorhombic, space group Pna2(1) (no. 3 3), a = 13.900(2) Angstrom, b = 6.9413(8) Angstrom, c = 11.219(2) Angstrom, V = 1082.4(2) Angstrom(3), Z = 8, R = 3.65%, R-w = 4.14% [2205 reflections with I > 3 sigma(I)].