Browsing by Author "Gozukara, Y"

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    The rockbridgeite group approved and a new member, ferrorockbridgeite, (Fe2+,Mn2+)2(Fe3+)3(PO4)3(OH)4(H2O), described from the Hagendorf Süd pegmatite, Oberpfalz, Bavaria
    (Schweizerbart Science Publishers, 2019-06-06) Grey, IE; Kampf, AR; Keck, E; Cashion, JD; MacRae, CM; Gozukara, Y; Peterson, VK; Shanks, FL
    The rockbridgeite group has been officially established by the IMA Commission on New Minerals, Nomenclature and Classification. The general formula is based on the structure and is A 2 B 3(PO4)3(OH, H2O)5, where A = the octahedrally coordinated M2 site, in which divalent cations are ordered, and B = the octahedrally coordinated M1 + M3 sites, which contain predominantly Fe3+, with trace Al. The different rockbridgeite-group minerals are distinguished by the occupancy of the A site. The ideal formula for rockbridgeite is F e 0.5 2 + Fe 0.5 3 + 2 Fe 3 3 + PO 4 3 OH 5 , that for frondelite is Mn 0.5 2 + Fe 0.5 3 + 2 Fe 3 3 + PO 4 3 OH 5 and that for plimerite is Z n 2 Fe 3 3 + P O 4 3 OH 4 ( H 2 O ) . In order to preserve the identity of frondelite and rockbridgeite within the structure-based formalism, these species correspond to mid-series compositions. We describe here the new end-member, ferrorockbridgeite, with dominant Fe2+ in the A site, from the Hagendorf Süd pegmatite mine, Oberpfalz, Bavaria. Electron microprobe analyses, coupled with Mössbauer spectroscopy, gives the empirical formula Fe 1.33 2 + Mn 0.52 2 + Zn 0.03 Ca 0.05 Fe 3.03 3 + Al 0.01 P 2.97 H 6.17 O 17 . The simplified formula is F e 2 + , M n 2 + 2 F e 3 3 + P O 4 3 OH 4 ( H 2 O ) . Ferrorockbridgeite is orthorhombic, space group Bbmm, with a = 13.9880(4), b = 16.9026(5), c = 5.1816(1) Å, V = 1225.1 Å3 and Z = 4. The six strongest lines in the X-ray powder diffraction pattern are [d meas/Å (I) (hkl)]: 4.853 (26) (101), 3.615 (24) (240), 3.465 (33) (301), 3.424 (39) (410), 3.205 (100) (321) and 1.603 (24) (642). Optically, ferrorockbridgeite is biaxial (–) with α = 1.763(3), β = 1.781(calc), γ = 1.797(3) (white light) and 2V (meas.) = 87(1)° from extinction data. The optical orientation is X = c, Y = a , Z = b. The pleochroism is X = blue green, Y = olive green, Z = yellow brown; X ≈ Y > Z. The rockbridgeite group has been officially established by the IMA Commission on New Minerals, Nomenclature and Classification. The general formula is based on the structure and is A 2 B 3(PO4)3(OH, H2O)5, where A = the octahedrally coordinated M2 site, in which divalent cations are ordered, and B = the octahedrally coordinated M1 + M3 sites, which contain predominantly Fe3+, with trace Al. The different rockbridgeite-group minerals are distinguished by the occupancy of the A site. The ideal formula for rockbridgeite is F e 0.5 2 + Fe 0.5 3 + 2 Fe 3 3 + PO 4 3 OH 5 , that for frondelite is Mn 0.5 2 + Fe 0.5 3 + 2 Fe 3 3 + PO 4 3 OH 5 and that for plimerite is Z n 2 Fe 3 3 + P O 4 3 OH 4 ( H 2 O ) . In order to preserve the identity of frondelite and rockbridgeite within the structure-based formalism, these species correspond to mid-series compositions. We describe here the new end-member, ferrorockbridgeite, with dominant Fe2+ in the A site, from the Hagendorf Süd pegmatite mine, Oberpfalz, Bavaria. Electron microprobe analyses, coupled with Mössbauer spectroscopy, gives the empirical formula Fe 1.33 2 + Mn 0.52 2 + Zn 0.03 Ca 0.05 Fe 3.03 3 + Al 0.01 P 2.97 H 6.17 O 17 . The simplified formula is F e 2 + , M n 2 + 2 F e 3 3 + P O 4 3 OH 4 ( H 2 O ) . Ferrorockbridgeite is orthorhombic, space group Bbmm, with a = 13.9880(4), b = 16.9026(5), c = 5.1816(1) Å, V = 1225.1 Å3 and Z = 4. The six strongest lines in the X-ray powder diffraction pattern are [d meas/Å (I) (hkl)]: 4.853 (26) (101), 3.615 (24) (240), 3.465 (33) (301), 3.424 (39) (410), 3.205 (100) (321) and 1.603 (24) (642). Optically, ferrorockbridgeite is biaxial (–) with α = 1.763(3), β = 1.781(calc), γ = 1.797(3) (white light) and 2V (meas.) = 87(1)° from extinction data. The optical orientation is X = c, Y = a , Z = b. The pleochroism is X = blue green, Y = olive green, Z = yellow brown; X ≈ Y > Z. The rockbridgeite group has been officially established by the IMA Commission on New Minerals, Nomenclature and Classification. The general formula is based on the structure and is A 2 B 3(PO4)3(OH, H2O)5, where A = the octahedrally coordinated M2 site, in which divalent cations are ordered, and B = the octahedrally coordinated M1 + M3 sites, which contain predominantly Fe3+, with trace Al. The different rockbridgeite-group minerals are distinguished by the occupancy of the A site. The ideal formula for rockbridgeite is F e 0.5 2 + Fe 0.5 3 + 2 Fe 3 3 + PO 4 3 OH 5 , that for frondelite is Mn 0.5 2 + Fe 0.5 3 + 2 Fe 3 3 + PO 4 3 OH 5 and that for plimerite is Z n 2 Fe 3 3 + P O 4 3 OH 4 ( H 2 O ) . In order to preserve the identity of frondelite and rockbridgeite within the structure-based formalism, these species correspond to mid-series compositions. We describe here the new end-member, ferrorockbridgeite, with dominant Fe2+ in the A site, from the Hagendorf Süd pegmatite mine, Oberpfalz, Bavaria. Electron microprobe analyses, coupled with Mössbauer spectroscopy, gives the empirical formula Fe 1.33 2 + Mn 0.52 2 + Zn 0.03 Ca 0.05 Fe 3.03 3 + Al 0.01 P 2.97 H 6.17 O 17 . The simplified formula is F e 2 + , M n 2 + 2 F e 3 3 + P O 4 3 OH 4 ( H 2 O ) . Ferrorockbridgeite is orthorhombic, space group Bbmm, with a = 13.9880(4), b = 16.9026(5), c = 5.1816(1) Å, V = 1225.1 Å3 and Z = 4. The six strongest lines in the X-ray powder diffraction pattern are [d meas/Å (I) (hkl)]: 4.853 (26) (101), 3.615 (24) (240), 3.465 (33) (301), 3.424 (39) (410), 3.205 (100) (321) and 1.603 (24) (642). Optically, ferrorockbridgeite is biaxial (–) with α = 1.763(3), β = 1.781(calc), γ = 1.797(3) (white light) and 2V (meas.) = 87(1)° from extinction data. The optical orientation is X = c, Y = a , Z = b. The pleochroism is X = blue green, Y = olive green, Z = yellow brown; X ≈ Y > Z. © 2018 E. Schweizerbart’sche Verlagsbuchhandlung
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    Ultra-flexible framework breathing in response to dehydration in liskeardite, [(Al,Fe)16(AsO4)9(OH)21(H2O)11]·26H2O, a natural open-framework compound
    (Elsevier, 2015-05-02) Grey, IE; Brand, HEA; Rumsey, MS; Gozukara, Y
    Dehydration of the natural open-framework compound, liskeardite, [(Al,Fe)16(AsO4)9(OH)21(H2O)11]·26H2O, is accompanied by a change in the sign of the thermal expansion from positive to negative above room temperature, and at ~100 °C the structure undergoes a dramatic 2D contraction by co-operative rotation of heteropolyhedral columns that constitute the framework walls. Monoclinic liskeardite, I112 with a≈b≈24.7 Å, c ≈7.8 Å and β≈90° is transformed to a tetragonal phase, I-4 with a≈20.6 Å, c ≈7.7 Å. The associated 30% decrease in volume is unprecedented in inorganic microporous compounds. The flexibility of the contraction is related to the double-hinged nature of the column rotations about [001]. Octahedra in adjacent columns are interconnected by corner-sharing with the two pairs of anions forming opposing edges of AsO4 tetrahedra, so a double-hinged rotation mechanism operates. Thermal analysis and mass spectroscopic results for liskeardite show that the phase transition at ~100 °C is related to removal of the channel water. The tetragonal phase shows exceptionally large NTE behaviour. Over the temperature range 148–178 the NTE along a and b is close to linear with a magnitude of the order of −900×10−6 °C−1. The contraction along the channel direction is smaller but still appreciable at −200×10−6 °C−1. © 2015 Elsevier Inc.