Die Kristallstruktur von Dizirkondiorthophosphat

Crystal structure, phase transition and anisotropic thermal expansion of barium zirconium diorthophosphate, BaZr(PO4)2

“…These values are in good agreement with those found in other orthophosphates Zr 2 O(PO 4 ) 2 [21], CaZr(PO 4 ) 2 [3] and SrZr(PO 4 ) 2 [1]. The Zr atom is sixfold coordinated with the mean Zr-O distance of 0.207 nm, which is comparable to those of the ZrO 6 octahedron in CuZr 2 (PO 4 ) 3 (the mean ¼ 0.207 nm) [22], CaZr 4 (PO 4 ) 6 (0.206 nm) [23] and K 2 Zr(PO 4 ) 2 (0.207 nm) [24].…”

Chemistry of tetravalent actinide phosphates—Part II

“…39-0207), zirconium [19,20,27,31,32], and hafnium [19,29] oxide phosphates were also presented in the literature in three forms. Gebert and Tillmanns [27] wrote for the first time the formula Zr 2 O(PO 4 ) 2 . Its crystal structure is built on a slightly distorted pentagonal bipyramid ZrO 7 [27].…”

“…The pentagonal bipyramid UO 7 is linked through linear U-O-U arrangements and bidentate phosphate tetrahedra. The U 2 O(PO 4 ) 2 structure (orthorhombic symmetry) belongs the same type than the dizirconium oxide phosphate Zr 2 O(PO 4 ) 2 [27]. Their unit-cell parameters are given in Table 2.…”

“…Gebert and Tillmanns [27] wrote for the first time the formula Zr 2 O(PO 4 ) 2 . Its crystal structure is built on a slightly distorted pentagonal bipyramid ZrO 7 [27]. Two modifications of this compound are reported.…”

High-pressure synthesis and crystal structure of silicon phosphate hydroxide, SiPO4(OH)

“…In the SiP 2 O 7 polymorphs, silicon is 6-coordinated, while in Si 5 O(PO 4 ) 6 unusual mixed 4,6-coordination is observed. With the exception of naturally-occurring thaumasite, Ca 3 (H 2 O) 12 (Si(OH) 6 )(CO 3 )(SO 4 ), the silicon phosphates are the only room pressure ionic crystalline phases known to possess SiO 6 units. This octahedral coordination extends to several silicophosphate polyanion-bearing compounds, including (NH 4 ) 2 SiP 4 O 13 [8], Rb 2 SiP 4 O 13 , Cs 2 H 2 Si(P 2 O 7 ) 2 , and BaH 2 Si(P 2 O 7 ) 2 [9].…”