Showing papers by "Ali Boukhari published in 1995"
TL;DR: In this article, the crystal structures of both α- and β-modifications of copper disodium diphosphate (Na2CuP2O7) were solved at 295 K.
44 citations
TL;DR: K2CuP2O7 as mentioned in this paper has a solid state structure that shows square pyramidal coordination for Cu2+ (Cu2+O, average 2.043(5) A) and sevenfold or ninefold coordination for the two potassium atoms (K ǫO, averaged 2.748(3) and 2.966(4) A respectively).
26 citations
TL;DR: In this article, a study of the crystal chemistry of the Ni 2 − x Mn x P 2 O 7 systems in powder form, 0 ≤ x ≤ 2, has revealed the existence of three solid solutions.
20 citations
TL;DR: In this paper, the Ba atom has three interactions with bridging O atoms in space group P62m with threefold axes passing through the P atoms, with P-O-P angles of 130 (1) and 134 (4)°.
Abstract: σ-Dibarium diphosphate, Ba 2 P 2 O 7 , crystallizes in space group P62m with the Ba atoms, separated by 4.703 A, arranged in columns. Ba atoms are in sites of eleven- and tenfold coordination with Ba(1)-O and Ba(2)-O distances in the ranges 2.776(8)-2.869(6) and 2.878(9)-3.080(9) A, respectively. One Ba atom has three interactions with bridging O atoms. P 2 O 7 groups have threefold axes passing through the P atoms. The bridging O atom is disordered about these axes, with P-O-P angles of 130 (1) and 134 (4)°.
20 citations
TL;DR: In this paper, four diphosphate compounds of the type AIIBIIP2O7 have been synthesized and characterized by single-crystal X-ray diffraction.
19 citations
TL;DR: In this article, the existence of face sharing NiO6 octahedra with Ni−Ni separation of 2.827 A (Ni−O; 1.93(2)−2.17(2), 2.81(2, 2.17) and 2.75(2).
Abstract: Crystalline K2NiP2O7 (I): monoclinic, P21,a=9.230(2),b=17.540(8),c=8.319(9)A, β=91.44(2)°,Z=8,dcalc=3.067 g cm−3, λMoKα=0.71069A,R/Rw=6.5/9.4%, is characterized by the existence of face sharing NiO6 octahedra with Ni−Ni separation of 2.827 A (Ni−O; 1.93(2)–2.17(2)A). K+ is seen in sites of seven, six, and fivefold coordination (K−O, averages; 2.83(2), 2.81(2), and 2.77(2)A, respectively) P2O74− groups are observed in semieclipsed conformation. K6Sr2Ni5(P2O7)5 (II) crystallizes in monoclinic space group P21/c;a=11.038(7),b=9.533(13),c=7.438(2)A, β=100.13(4)°,Dcalc=3.309 g cm−3,Z=2,R/Rw=6.4/8.1%. Nickel atoms are distributed on planes parallel to the crystallographic (100) plane at χ=0 and χ=0.5. On the planes, χ=0, Ni2+ ions form successive linked trimers of edge sharing NiO6 octahedra (Ni−Ni, 3.018(1), 3.008(1)A; Ni−O, av 2.07(2)A). The intermediate planes (χ=0.5) contain isolated and six coordinate Ni2+ ions (Ni−O av. 2.09(2)A). Seven-coordinate potassium ions (K−O, av. 2.74(2)A) are located on intermediate planes at χ=0.25 and 0.75. P2O74− 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)A).
19 citations
TL;DR: In this article, single-crystal X-ray diffraction of mixed metal diphosphates PbCo3(P2O7)2 (I) and PbFe3(p2O 7)2(II) has been performed.
10 citations
TL;DR: SrFe 2 III (P 2 O 7 ) 2 [strontium diiron(III) bis(diphosphate)] was prepared using high-temperature fusion and was found to crystallize in the triclinic space group P1.
Abstract: SrFe 2 III (P 2 O 7 ) 2 [strontium diiron(III) bis(diphosphate)] was prepared using high-temperature fusion and was found to crystallize in the triclinic space group P1. The Fe III atoms have distorted octahedral coordination geometry [average Fe-O 1.996 (3) A] and the Sr atoms are in sites of eightfold coordination [average Sr-O 2.739 (3) A]. Columns of alternating Sr and Fe atoms are observed at x=1/2, y=0, whereas columns of widely separated Fe atoms are seen at x=0, y=1/2
4 citations
TL;DR: In this paper, the Ba atom has three interactions with bridging O atoms in space group P62m with threefold axes passing through the P atoms, with P-O-P angles of 130 (1) and 134 (4)°.
Abstract: σ-Dibarium diphosphate, Ba 2 P 2 O 7 , crystallizes in space group P62m with the Ba atoms, separated by 4.703 A, arranged in columns. Ba atoms are in sites of eleven- and tenfold coordination with Ba(1)-O and Ba(2)-O distances in the ranges 2.776(8)-2.869(6) and 2.878(9)-3.080(9) A, respectively. One Ba atom has three interactions with bridging O atoms. P 2 O 7 groups have threefold axes passing through the P atoms. The bridging O atom is disordered about these axes, with P-O-P angles of 130 (1) and 134 (4)°.
2 citations
Journal Article•
TL;DR: A calcium nickel orthophosphate complex has been isolated and shown to display a solid state structure similar to that of α-Ca 3 (PO 4 ) 3 with columns of cations surrounded by (PO4 )-nickel-(PO 4 ), vacancy columns in hexagonal array as mentioned in this paper.
Abstract: A calcium nickel orthophosphate complex has been isolated and shown to display a solid state structure similar to that of α-Ca 3 (PO 4 ) 3 with columns of cations surrounded by (PO 4 )-nickel-(PO 4 )-vacancy columns in hexagonal array. Calcium and nickel atoms are distributed within the cation columns. Ca 8.5 Ni 9.5 (PO 4 ) 12 (space group C2/c, a = 22.819(5) A, b = 9.944(2) A, c = 16.982(3) A, β = 99.97(3)°, D calc = 3.67 g cm -3 , Z = 4, R = 5.59% for 3216 obs. refls.) shows cation columns to contain 29.2% nickel and 70.8% calcium atoms.
2 citations
TL;DR: In this article, four diphosphate compounds of the type AIIBIIP2O7 have been synthesized and characterized by single-crystal X-ray diffraction.
Abstract: Four new diphosphate compounds of the type AIIBIIP2O7 have been synthesized and characterized by single-crystal X-ray diffraction. While all four have similar unit cell dimensions, BaPbP2O7 is isotypical with α-Sr2P2O7 (space group Pmnb), whereas PbCoP2O7, PbMnP2O7 and PbCuP2O7 are similar to α-Ca2P2O7 (space group P21/n). P2O74 groups show average OP ⋯ PO angles which range from 0.0° to 49.56° and are intermediate between 0.0° expected of dichromate-type structures and the 60.0° expected of thorveities. The magnitude of the OP ⋯ PO angle is correlated with the ionic radius of the smaller cation in each compound. Furthermore, the change in space group for BaPbP2O7 may be seen to be a consequence of the ionic radii of the B atom. Metal coordination numbers in the four complexes range from 5 to 9.
TL;DR: SrFe 2 III (P 2 O 7 ) 2 [strontium diiron(III) bis(diphosphate)] was prepared using high-temperature fusion and was found to crystallize in the triclinic space group P1.
Abstract: SrFe 2 III (P 2 O 7 ) 2 [strontium diiron(III) bis(diphosphate)] was prepared using high-temperature fusion and was found to crystallize in the triclinic space group P1. The Fe III atoms have distorted octahedral coordination geometry [average Fe-O 1.996 (3) A] and the Sr atoms are in sites of eightfold coordination [average Sr-O 2.739 (3) A]. Columns of alternating Sr and Fe atoms are observed at x=1/2, y=0, whereas columns of widely separated Fe atoms are seen at x=0, y=1/2
Abstract: Cd2.06FemFe~.44(P207)2 crystallizes in the orthorhombic space group C2221 with Fe III in a distorted octahedral environment [average F e O 2.05 (1)A] and FeII sharing sites with Cd atoms in two sites of sixfold coordination [average Cd/Fe--O 2.20 (1)A]. Two further Cd atoms show sixfold coordination with average Cd---O