New data on vibrational properties of calcium oxalates and their controversial transformation mechanism are presented. We have focused on whewellite (CaC2O4·H2O) and weddellite [CaC2O4·(2 + x) H2O], the most common phases of calcium oxalate; these compounds occur in many organisms, in kidney stones and in particular kinds of films found on the surface of many works of art. Low temperature experiments carried out by Fourier transform infrared spectroscopy have highlighted both the high structural order in the crystalline state of whewellite and the disordered distribution of the zeolitic water molecules in weddellite. The synthesised nanocrystals of weddellite have been kept under different hygrometric conditions in order to study, by X-ray powder diffraction, the role of "external" water molecules on their stability. Moreover, in order to identify the different kinds of water molecules, a re-investigation, supported by quantum chemical calculations, of the observed vibrational spectra (IR and Raman) of whewellite has been conducted. © 2014 Published by Elsevier B.V.

Conti, C., Casati, M., Colombo, C., Realini, M., Brambilla, L., Zerbi, G. (2014). Phase transformation of calcium oxalate dihydrate-monohydrate: Effects of relative humidity and new spectroscopic data. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY, 128, 413-419 [10.1016/j.saa.2014.02.182].

Phase transformation of calcium oxalate dihydrate-monohydrate: Effects of relative humidity and new spectroscopic data

CASATI, MARCO;
2014

Abstract

New data on vibrational properties of calcium oxalates and their controversial transformation mechanism are presented. We have focused on whewellite (CaC2O4·H2O) and weddellite [CaC2O4·(2 + x) H2O], the most common phases of calcium oxalate; these compounds occur in many organisms, in kidney stones and in particular kinds of films found on the surface of many works of art. Low temperature experiments carried out by Fourier transform infrared spectroscopy have highlighted both the high structural order in the crystalline state of whewellite and the disordered distribution of the zeolitic water molecules in weddellite. The synthesised nanocrystals of weddellite have been kept under different hygrometric conditions in order to study, by X-ray powder diffraction, the role of "external" water molecules on their stability. Moreover, in order to identify the different kinds of water molecules, a re-investigation, supported by quantum chemical calculations, of the observed vibrational spectra (IR and Raman) of whewellite has been conducted. © 2014 Published by Elsevier B.V.
Articolo in rivista - Articolo scientifico
FTIR spectroscopy; Quantum chemical calculation; Raman spectroscopy; Weddellite; Whewellite; X-ray diffraction; Instrumentation; Atomic and Molecular Physics, and Optics; Analytical Chemistry; Spectroscopy
English
2014
128
413
419
none
Conti, C., Casati, M., Colombo, C., Realini, M., Brambilla, L., Zerbi, G. (2014). Phase transformation of calcium oxalate dihydrate-monohydrate: Effects of relative humidity and new spectroscopic data. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY, 128, 413-419 [10.1016/j.saa.2014.02.182].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/54148
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