TPR, EPR and UV-Vis studies of Ni(II) speciation in chrysoprase

Authors: Sojka, Zbigniew; Witkowski, Stefan; Zdot abi nacute ski, Witold; Dyrek, Krystyna; Bidzi nacute ska, Ewa

Source: Neues Jahrbuch für Mineralogie - Monatshefte, Volume 2004, Number 1, 1 January 2004 , pp. 11-25(15)

Publisher: E. Schweizerbart'sche Verlagsbuchhandlung

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Abstract:

TPR (Temperature Programmed Reduction) and EPR (Electron Paramagnetic Resonance) corroborated with UV-Vis methods were used to get a new insight into the status of nickel ions in chrysoprases from various localities. The investigation showed speciation of Ni into 2:1 highly dispersed phyllosilicates and extra-framework species grafted on the surface of chalcedony matrix. Both kinds of nickel exhibit a distorted octahedral coordination giving rise to a broad EPR spectrum with g = 2.17 and three characteristic d-d bands that can be parameterised with 10Dq = 8897cm^-1 and B = 953cm^-1.

Keywords: CHRYSOPRASE; NI-SPECIATION; TPR; EPR; UV-VIS

Document Type: Regular paper

DOI: 10.1127/0028-3649/2004/2004-0011

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