Queitite, a mineral new to Britain, from the Caldbeck Fells, Cumbria

Braithwaite, R. S. W.; Cooper, Michael P.; Hart, Alan D.

doi:10.1180/minmag.1989.053.372.11

Cited by 17 publications

(35 citation statements)

References 2 publications

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“…In agreement with the literature data, [23] four bands of almost equal intensity are observed for mineral aurichalcite at 1556, 1506, 1411 and 1363 cm -1 . These bands are found at slightly higher wavenumbers in the spectrum of the synthetic aurichalcite sample, although the intensity pattern differs between the mineral and synthetic samples.…”

Section: Vibrational Spectroscopysupporting

confidence: 93%

Minerals as Model Compounds for Cu/ZnO Catalyst Precursors: Structural and Thermal Properties and IR Spectra of Mineral and Synthetic (Zincian) Malachite, Rosasite and Aurichalcite and a Catalyst Precursor Mixture

et al. 2009

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The Cu/ZnO system is a model for Cu/ZnO/Al2O3 catalysts, which are employed industrially for the synthesis of methanol. These catalysts are usually prepared from mixed basic carbonate precursors. A complex phase mixture, with constituents structurally related to the minerals rosasite andaurichalcite, is present at the industrially applied composition (Cu/Zn ≈ 70:30). Using minerals and phase‐pure synthetic samples as references, a comprehensive characterisation of such a phase mixture, including the determination of the individual compositions of the different phases, has been attempted by complementary analytical laboratory techniques (XRD, TGA, IR). The results are critically discussed in light of the complexity of the system. A thermally very stable carbonate species ― well‐known for mixed synthetic systems ― is also detected for the mineral reference samples. Significant amounts of amorphous phases are found to be present in the synthetic zincian malachite sample but not in synthetic aurichalcite or the catalyst precursor. A simplified explanation for the shift of the characteristic 20$\bar {1}$ reflection of the malachite structure as a function of Zn incorporation based on the varying average Jahn–Teller distortion of the MO6 octahedra is proposed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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Section: Vibrational Spectroscopysupporting

confidence: 93%

Minerals as Model Compounds for Cu/ZnO Catalyst Precursors: Structural and Thermal Properties and IR Spectra of Mineral and Synthetic (Zincian) Malachite, Rosasite and Aurichalcite and a Catalyst Precursor Mixture

et al. 2009

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“…Moreover, it is possible to observe another weak and broad band at 3445 cm Ϫ1 assigned to stretching vibrations of M-O-H groups as was shown in [Zn 2 (OH)AsO 4 ] [11]. These large absorption bands together with the minor peak observed at about 1635 cm Ϫ1 indicate the presence of OH groups in the crystal structure and the absence of crystalhydrate water molecules [27] in good agreement with the structural results. Using a simple crystal-field approximate model corresponding to an energy level diagram for an octahedral d 7 system, the ligand-field splitting parameter 10Dq and the Racah parameter B may be calculated from the energies of the two higher spin-allowed transitions [30].…”

Section: Spectroscopic Measurementssupporting

confidence: 85%

“…Different type of phosphates and arsenates with defined structural type can be identified by IR spectroscopy and good correlations between the essential vibrational features and the structural data can be obtained [25,26]. The infrared spectrum of [Co 1.7 Mn 0.3 (OH)PO 4 ] shows three distinct features corresponding principally to the vibrations of the hydroxide and phosphate groups [27,28] appears at a frequency similar to those observed for the isomorphous adamite [11] and olivenite [29] compounds. Moreover, it is possible to observe another weak and broad band at 3445 cm Ϫ1 assigned to stretching vibrations of M-O-H groups as was shown in [Zn 2 (OH)AsO 4 ] [11].…”

Section: Spectroscopic Measurementsmentioning

confidence: 99%

Spectroscopic and Magnetic Properties of Co_1.7Mn_0.3(OH)PO₄

Pedro

Rojo

Lezama

et al. 2007

Zeitschrift anorg allge chemie

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Co 1.7 Mn 0.3 (OH)PO 4 has been prepared under mild hydrothermal conditions and characterized from powder X-ray diffraction. IR data are characteristic of three distinct features corresponding principally to the vibrations of the hydroxide and [PO 4 ] 3Ϫ anions. UV-Visible studies show the existence of bands ascribed to the chromophores of Co ions in two coordination polyhedra, octahedral and trigonal bipyramidal. The magnetic behaviour indicates the existence of antiferromagnetic interactions as predominant. Magnetization measurements show the presence of two maxima at 65 K and 9 K, respectively. The first peak was attributed to a three-dimensional antiferromagnetic ordering and the second one reveals the possible existence of a spin-glass like state. The substitution of Co 2ϩ (S ϭ 3/2) by Mn 2ϩ (S ϭ 5/2) ions at about 15 % keeps the two magnetic transitions observed in the non-sub-1847 stituted phase. ZFC-FC curves show magnetic irreversibility at temperatures just below T N due to the spin decompensations in Co 1.7 Mn 0.3 (OH)PO 4 . The remanent magnetization indicates higher ferromagnetic interactions at lower temperatures than that observed in the ordered Co 2 (OH)PO 4 phase. These results could be attributed to the existence of a spin-glass state similar to that exhibited by the Co 2 (OH)PO 4 and substituted Co 2Ϫx M x (OH)PO 4 (M ϭ Ni, Cu; x ϭ 0.1Ϫ0.3) compounds. A comparative magnetic study with the analogous Ni 2ϩ (S ϭ 1) and Cu 2ϩ (S ϭ 1/2) phases is carried out.

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“…The monoclinic structure of clinoatacamite is easily transformable to a pseudorhombohedral cell approximating that of paratacamite by substitution of part of the Cu ions. [32,33] However, in the absence of Ni, Zn or Co cations, the mineral phase more likely to form is clinoatacamite rather than paratacamite. In fact, the Raman spectral features recorded in the samples from the Hall of the Kings with three characteristic bands at 3440, 3348 and 3309 cm À1 together with those at 142, 362, 511, 897, 933 and 967 cm À1 are strongly coincident with those reported for clinoatacamite.…”

Section: Laboratory Studies: Micro-invasive Analysismentioning

confidence: 99%

Decorated plasterwork in the Alhambra investigated by Raman spectroscopy: comparative field and laboratory study

Domínguez‐Vidal

Torre-López

Campos-Suñol

et al. 2014

J Raman Spectroscopy

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This work presents the results of the study of plasterwork decorations located on the stalactite vaults of the Hall of the Kings in the Alhambra (Granada, Spain) by means of Raman micro‐spectroscopy. Field investigations were carried out in situ using a portable Raman spectrometer during a conservation campaign in a completely non‐invasive manner. In addition, taking into account the results obtained, a well‐directed sampling was carried out to obtain complementary information by means of laboratory studies. Despite several practical problems during the non‐invasive field studies (like difficulties for probe positioning and vibrations of the scaffolding), almost all the pigments present in the decorations of the Hall were identified using excitation at 785 nm: cinnabar, minium, carbon black, natural lapis lazuli and synthetic ultramarine blue. In addition, evidence of different degradation mechanisms of the red pigments was obtained in situ. On the contrary, the identification of blue‐greenish and green pigments had to be performed on microsamples using a Raman microscope with excitation at 514 nm in the laboratory. In samples with blue and green areas, azurite severely degraded to clinoatacamite was identified. These were probably the remains of the oldest blue decorations. In addition, a technique for green decorations consisting on copper chlorides mixed with a small amount of lapis lazuli was identified. Other degradation products, identified in the laboratory regardless of the color of the pigment, were calcium oxalates. Finally, the laboratory studies also enabled the investigation of the stratigraphy of the pictorial layers. In this way, the presence of re‐decorations with overlaying layers of pigments even of different colors was revealed. Copyright © 2014 John Wiley & Sons, Ltd.

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Queitite, a mineral new to Britain, from the Caldbeck Fells, Cumbria

Cited by 17 publications

References 2 publications

Minerals as Model Compounds for Cu/ZnO Catalyst Precursors: Structural and Thermal Properties and IR Spectra of Mineral and Synthetic (Zincian) Malachite, Rosasite and Aurichalcite and a Catalyst Precursor Mixture

Minerals as Model Compounds for Cu/ZnO Catalyst Precursors: Structural and Thermal Properties and IR Spectra of Mineral and Synthetic (Zincian) Malachite, Rosasite and Aurichalcite and a Catalyst Precursor Mixture

Spectroscopic and Magnetic Properties of Co_1.7Mn_0.3(OH)PO₄

Decorated plasterwork in the Alhambra investigated by Raman spectroscopy: comparative field and laboratory study

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Queitite, a mineral new to Britain, from the Caldbeck Fells, Cumbria

Cited by 17 publications

References 2 publications

Minerals as Model Compounds for Cu/ZnO Catalyst Precursors: Structural and Thermal Properties and IR Spectra of Mineral and Synthetic (Zincian) Malachite, Rosasite and Aurichalcite and a Catalyst Precursor Mixture

Minerals as Model Compounds for Cu/ZnO Catalyst Precursors: Structural and Thermal Properties and IR Spectra of Mineral and Synthetic (Zincian) Malachite, Rosasite and Aurichalcite and a Catalyst Precursor Mixture

Spectroscopic and Magnetic Properties of Co1.7Mn0.3(OH)PO4

Decorated plasterwork in the Alhambra investigated by Raman spectroscopy: comparative field and laboratory study

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Spectroscopic and Magnetic Properties of Co_1.7Mn_0.3(OH)PO₄