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polyoxocation

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Journal Article
Published: 01 June 2022
American Mineralogist (2022) 107 (6): 1181–1189.
... O 28 ] 6− decavanadate polyoxoanion and a novel [Al 4 (OH) 6 (H 2 O) 12 ] 6+ polyoxocation. * E-mail: akampf@nhm.org . Manuscript handled by G. Diego Gatta 17 3 2021 16 6 2021 Copyright © 2022 by the Mineralogical Society of America 2022 Mineralogical Society...
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Powder XRD patterns of Mt clay exchanged with Al <span class="search-highlight">polyoxocations</span> at differen...
Published: 01 December 2017
Fig. 1. Powder XRD patterns of Mt clay exchanged with Al polyoxocations at different ratios (R) of mmol of Al/g of clay: (a) R = 0, (b) R = 3, (c) R = 6, (d) R = 12 and (e) R = 24.
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Solid  27 Al MAS NMR spectra of: (a) Mt clay, (b) exchanged with Al polyoxo...
Published: 01 December 2017
Fig. 4. Solid 27 Al MAS NMR spectra of: (a) Mt clay, (b) exchanged with Al polyoxocations at a ratio of 6 mmol of Al per g of clay (Mt); (c) then reacted with C12 amine and TEOS solutions; (d) corresponds to sample (c) calcined at 550°C.
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DTG features of: (a) Mt clay exchanged with Al <span class="search-highlight">polyoxocations</span> at (b) a rati...
Published: 01 December 2017
Fig. 5. DTG features of: (a) Mt clay exchanged with Al polyoxocations at (b) a ratio of 3 mmol of Al/g of clay and (c) at a ratio of 6 mmol of Al/g of clay. b′ and c′ correspond to samples b and c reacted with C 12 amine and TEOS solutions, respectively.
Journal Article
Published: 01 January 2020
American Mineralogist (2020) 105 (1): 123–131.
... vanadoaluminate heteropolycation (“flat-Al 10 V☐ 2 ”), ideally [(V 5+ O 2 )Al 10 (OH) 20 (H 2 O) 18 ] 11+ , closely related to the technologically important flat-Al 13 polyoxocation. * E-mail: akampf@nhm.org Manuscript handled by G. Diego Gatta 25 6 2019 31 8 2019 Copyright © 2020...
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Solid  29 Si NMR spectra of: (a) Mt clay, (b) exchanged with Al polyoxocati...
Published: 01 December 2017
Fig. 3. Solid 29 Si NMR spectra of: (a) Mt clay, (b) exchanged with Al polyoxocations at a ratio of 6 mmol of Al/g of clay; (c) then reacted with C12 amine and TEOS solutions; (d) and (e) correspond to sample (c) after calcination at 550°C and 750°C, respectively.
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Polyhedral representation of the Al 13 O 4 (OH) 24 (OH 2 ) 12  7+  (aq) pol...
Published: 01 June 2001
F ig . 4. Polyhedral representation of the Al 13 O 4 (OH) 24 (OH 2 ) 12 7+ (aq) polyoxocation, which has a structure similar to an ε-Keggin molecule. The solid symbols (•) denote a six-membered ring of edge-shared AlO 6 octahedra to be compared with Fig. 2 .
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The basal surface of bayerite (γ-Al(OH) 3 ) with the oxygen sites labelled ...
Published: 01 June 2001
F ig . 2. The basal surface of bayerite (γ-Al(OH) 3 ) with the oxygen sites labelled as in Fig. 1 . The solid symbols (•) denote a six-membered ring of edge-shared AlO 6 octahedra to be compared with the polyoxocation in Fig. 4 . All of the sites can potentially change their protonation states
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Powder XRD patterns of Al( X ) PCH precursors that were prepared from Al po...
Published: 01 December 2017
Fig. 2. Powder XRD patterns of Al( X ) PCH precursors that were prepared from Al polyoxocation-intercalated clays at different ratios (R) of mmol of Al/g of clay: (a, a′) R = 0, (b, b′) R = 3, (c, c′) R = 6, (d, d′) R = 12 and (e, e′) R = 24 before and after (prime) calcination at 550°C.
Journal Article
Published: 01 April 2001
Clays and Clay Minerals (2001) 49 (2): 183–185.
...-pillared smectites modified with Ce and La. Pillaring of clays with Al polyoxocations (Keggin type Al 13 ) and a large variety of other complexing cations has been reported many times since the seventies. McCauley (1988) described in a patent the preparation of thermally stable pillared clays with large...
Journal Article
Published: 01 December 2005
Clays and Clay Minerals (2005) 53 (6): 613–621.
... chloride ions which could prevent the diffusion of polyoxocations within the interlayer space ( Palinko et al. , 1996 ). The solid was air dried and the resulting product was calcined for 2 h at different temperatures. The conditions used in the preparation of all the materials described are shown...
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Journal Article
Published: 01 November 2014
American Mineralogist (2014) 99 (11-12): 2337–2343.
...-exchanges and dissociations at the solution-oxide interface. Here we suggest the feasibility of making other heteroatom substitutions in the MAl 12 class of polyoxocations ( Johansson 1960 ), having the stoichiometry [MO 4 Al 12 (OH) 24 (H 2 O) 12 ] 6/7/8/+ and having the ɛ-isomer structure...
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Journal Article
Journal: Clay Minerals
Published: 01 December 2017
Clay Minerals (2017) 52 (4): 521–535.
...Fig. 1. Powder XRD patterns of Mt clay exchanged with Al polyoxocations at different ratios (R) of mmol of Al/g of clay: (a) R = 0, (b) R = 3, (c) R = 6, (d) R = 12 and (e) R = 24. ...
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Journal Article
Published: 01 January 2001
Reviews in Mineralogy and Geochemistry (2001) 44 (1): 167–190.
...) that are made up of dimers of δ-Keggin structure, which have one trimeric group rotated so that its Al(O) 6 polyhedra share corners with the rest of the molecule, not edges as in the ε-Keggin structure. The δ-Keggin isomer of the Al 13 molecule is a key intermediate in the formation of larger polyoxocations...
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Journal Article
Published: 01 December 2000
Clays and Clay Minerals (2000) 48 (6): 699–707.
... crystallize by accretion of metastable dissolved polyoxocations ( Fu et al. , 1991 ; Bradley et al. , 1993 ; Bradley and Hanna, 1994 ) and not from de novo nucleation from dissolved monomers in solution. Using spectroscopy, metastable dimers, trimers, and multimeric polyoxocations have been identified...
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Journal Article
Published: 01 December 2006
Clays and Clay Minerals (2006) 54 (6): 737–747.
... Alkoxide Clays PILCs Review Synthesis TiCl 4 Titanium The use of inorganic hydrated polyoxocations as pillaring agents provided thermally stable pillared clays with large specific surface areas ( Kloprogge, 1998 ). Several single and mixed-oxide pillars have been prepared using...
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Journal Article
Published: 01 June 2001
Mineralogical Magazine (2001) 65 (3): 323–337.
...F ig . 4. Polyhedral representation of the Al 13 O 4 (OH) 24 (OH 2 ) 12 7+ (aq) polyoxocation, which has a structure similar to an ε-Keggin molecule. The solid symbols (•) denote a six-membered ring of edge-shared AlO 6 octahedra to be compared with Fig. 2 . ...
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Journal Article
Published: 01 January 2014
American Mineralogist (2014) 99 (1): 128–138.
... the plane in Figs. 9a and 9b ) are considered less reactive as they are bound to the underlying TOT layer via hydrogen bonds. Work on the mechanism of oxygen exchange on the alumina ɛ-keggin polyoxocations has revealed an alternate hypothesis. These molecules are composed of sets of three aluminum...
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Journal Article
Published: 01 June 2003
Clays and Clay Minerals (2003) 51 (3): 340–349.
... Pillared clays (PILCs) are porous materials obtained by intercalation with bulky polyoxocations of swelling clays, mainly montmorillonites. After calcination at temperatures usually in the range 350–500°C, the intercalated polyoxocations are transformed into rigid oxide pillars, giving pillared clays...
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Journal Article
Published: 01 February 2003
Clays and Clay Minerals (2003) 51 (1): 41–51.
... thermal and hydrothermal stability. The search for such systems resulted in renewed interest in the concept of pillared clays. The use of inorganic hydrated polyoxocations as pillaring agents provided thermally stable pillared clays with large specific surface areas ( Kloprogge, 1998 ). On the other...
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