Untitled

Synthesis and structural characterization of AMV2O8(A = K, Rb, Tl, Cs; M = Nb, Ta) vanadates: a structural comparison of A+M5+V2O8vanadates and A+M5+P2O8phosphates

“…7) is of interest. The nine ASbP 2 O 8 (A = K, Rb, Cs, Tl), ATaP 2 O 8 (A = K, Rb, Cs, Tl) and CsNbP 2 O 8 phosphates have the layered yavapaiite structure 24,[26][27][28][29][30][31] and, as in layered CsSbV 2 O 8 vanadate, 52 [35][36][37][38][39][40][41] It is realised in the present study that this structure also could be imagined to be built from a connectivity of each M 2 P 4 O 18 ribbon to four such ribbons. In this structure type, 35 the blue and yellow PO 4 tetrahedral rows of one M 2 P 4 O 18 ribbon are respectively cornerconnected to yellow and blue PO 4 tetrahedral rows of other (Fig.…”

“…The seven structure types observed for these phosphates are the yava-paiite structure 13 of BaGeP 2 O 8 , the modified yavapaiite structure 15 of BaThP 2 O 8 , the cheralite structure 16 of CaThP 2 O 8 , the ordered cheralite structure 20 of SrNpP 2 O 8 and the distinct three-dimensional structures [21][22][23] of CaZrP 2 O 8 , PbVP 2 O 8 and PbSnP 2 O 8 . On the other hand, AMP 2 O 8 (A = K, Rb, Cs, Tl; M = Nb, Ta, Sb), RbVP 2 O 8 , AMoP 2 O 8 (A = Li, Na, K, Cs), AWP 2 O 8 (A = K, Rb) are the nineteen known A + M 5+ P 2 O 8 phosphates, [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] which have five structure types, namely, yavapaiite 25 KSbP 2 O 8 , layered 30 CsNbP 2 O 8 , three-dimensional 34 LiMoP 2 O 8 and two distinct three-dimensional polymorphic modifications 35,42 of KNbP 2 O 8 . In all of these A + M 5+ P 2 O 8 phosphates, M 5+ ions are octahedrally coordinated.…”

Novel tantalum phosphate Na13Sr2Ta2(PO4)9: synthesis, crystal structure, DFT calculations and Dy3+-activated fluorescence performance

“…As one of the closed-shell transition-metal ions, pentavalent tantalum is usually in a TaO 6 octahedral geometry, and can be introduced into PO 4 -based structures to generate various multiple tantalum phosphate compounds. Up to now, about a dozen different kinds of such compounds have been reported, such as Ta 2 Cd(P 2 O 7 ) 3 (Averbuch-Pouchot & Durif, 1987), TlTa(PO 4 ) 2 (Murashova et al, 2001) and PbTa 3 (PO 4 )(P 2 O 7 ) 3.5 (Murashova et al, 2003). Alternatively, there may be advantages to using Ta 2 O 5 , including high melting point and strong corrosion resistance, making such tantalum phosphate compounds potential candidates for luminescent host matrices.…”