Crystal structures of the new diphosphates, K{sub 2}NiP{sub 2}O{sub 7} and K{sub 6}Sr{sub 2}Ni{sub 5}(P{sub 2}O{sub 7}){sub 5}
- Oklahoma State Univ., Stillwater, OK (United States)
Crystalline K{sub 2}NiP{sub 2}O{sub 7} (I): monoclinic, P{sub 2}{sub 1}, a = 9.230(2), b = 17.540(8), c = 8.319(9){angstrom}, {beta} = 91.44(2){degrees}, Z = 8, d{sub calc} = 3.067 g cm{sup -3}, {lambda}MoK{sub {alpha}} = 0.71069{angstrom}, R/R{sub w} = 6.5/9.4%, is characterized by the existence of face sharing NiO{sub 6} octahedra with Ni-Ni separation of 2.827{angstrom} (Ni-O; 1.93(2) - 2.17(2){angstrom}). K{sup +} is seen in sites of seven, six, and fivefold coordination (K-O, averages; 2.83(2), 2.81(2), and 2.77(2){angstrom}, respectively). P{sub 2}O{sub 7}{sup 4-} groups are observed in semieclipsed conformation. K{sub 6}Sr{sub 2}Ni{sub 5}(P{sub 2}O{sub 7}){sub 5} (II) crystallizes in monoclinic space group P2{sub 1}/c; a = 11.038(7), b = 9.533(13), c = 7.438(2){angstrom}, {beta} = 100.13(4){degrees}, D{sub calc} = 3.309 g cm{sup -3}, Z = 2, R/R{sub w} = 6.4/8.1%. Nickel atoms are distributed on planes parallel to the crystallographic (100) plane at x = 0 and x = 0.5. On the planes, x = 0, Ni{sup 2+} ions form successive linked trimers of edge sharing NiO{sub 6} octahedra (Ni-Ni, 3.018(1), 3.008(1){angstrom}; Ni-O, av 2.07(2){angstrom}). The intermediate planes (x=0.5) contain isolated and six coordinate Ni{sup 2+} ions (Ni-O av. 2.09(2){angstrom}). Seven-coordinate potassium ions (K-O, av. 2.74(2){angstrom}) are located on intermediate planes at x = 0.25 and 0.75. P{sub 2}O{sub 7}{sup 4-} groups are found in eclipsed conformation. Strontium atoms are located between nickel and potassium planes and are surrounded by seven oxygen atoms (Sr-O, av. 2.586(2){angstrom}).
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 244014
- Journal Information:
- Journal of Chemical Crystallography, Vol. 25, Issue 9; Other Information: PBD: Sep 1995
- Country of Publication:
- United States
- Language:
- English
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