Non-hydrothermal synthesis of copper-, zinc- and copper-zinc hydrosilicates |
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Authors: | T M Yurieva G N Kustova T P Minyukova E K Poels A Bliek M P Demeshkina L M Plyasova T A Krieger V I Zaikovskii |
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Affiliation: | (1) Boreskov Institute of Catalysis, Novosibirsk 630090, Russia e-mail: yurieva@catalysis.nsk.su Tel.: +7-3832-34-41-09, Fax: +73832-34-3056, RU;(2) University of Amsterdam, Amsterdam, The Netherlands, NL |
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Abstract: | Cu/SiO2, Zn/SiO2 and Cu-Zn/SiO2 samples have been prepared by the homogeneous deposition-precipitation method. The samples were analyzed by thermal analysis,
X-ray diffraction and infrared spectroscopy after various heat treatments and compared with data obtained for several minerals.
It has been shown that interaction between the components occurs through formation of hydrosilicates. Copper-silica system
at a Cu:Si ratio ≤ 1, gives rise to a hydrosilicate stable up to a calcination temperature of 930 K resembling the mineral
Chrisocolla; at higher ratios a hydroxonitrate (gerhardite type) is also formed. Zinc-silica interaction produces two hydrosilicates
such as a well crystallized Hemimorphite at Zn:Si = 2 and highly dispersed Zincsilite at Zn:Si ≤ 0.75, both stable up to 1073
K. The Zincsilite structure consists of three layered sheets (an octahedral layer sandwiched by two tetrahedral ones) like
the Stevensite mineral group. For the copper-zinc-silica system no copper hydrosilicate is formed. Copper merely enters the
Zincsilite structure independenly of the applied (Cu + Zn):Si ratio. Resulting layered copper-zinc hydrosilicate may be described
by formula
Znx-yCuy(Zn3-x–zCuz–y▪x)Si4O10](OH)2.nH2O,
where Zn3-x-zCuz-y– ions are located in octahedral sites, Znx-yCuy–ions in the interlayer; ▪x are vacancies in the layers. Copper and zinc in excess of the Zincsilite ratio of Me:Si = 0.75, gives rise to copper and
copper-zinc hydroxonitrates.
Received: 7 November 2000 / Reviewed: 23 January 20001 / Accepted: 23 January 2001 |
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Keywords: | CuO/SiO2 ZnO/SiO2 CuO/ZnO/SiO2 Non-hydrothermal synthesis of layer silicates Homogeneous deposition-precipitation |
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