Differential scanning calorimetry (DSC) and particle size measurements were carried out on disproportionation products of pure SnO to investigate the fusion and solidification behaviour of Sn droplets and their catalytic nucleation on Sn oxides. If disproportionation reaction takes place at T >= 798 K, the products are metallic Sn and SnO2; but for 523 < T < 798 K, SnO2 is replaced by an intermediate oxide (IO) SnxO(1+x). On melting, samples with 10 show a drop of melting point of metallic tin due to Gibbs-Thomson effect; no lowering of melting point was observed in samples with SnO2. On the other hand, if solidification occurs in the presence of IO, Tin droplets always displayed three distinct exothermic solidification peaks, but if it takes place in the presence of SnO2, only one exothermic peak is observed. Undercooling values and contact angles were determined for each of the heterogeneous nucleation processes. The different behaviour of metallic Tin droplets was related to the different lattice symmetry of SnO2 and IO, which act as nucleation catalysts. (c) 2004 Elsevier B.V. All rights reserved.
Solidification of metallic tin in dispersed phase / Bonicelli, Maria Grazia; Gianfranco, Ceccaroni; Franco, Gauzzi; Giuseppe, Mariano. - In: THERMOCHIMICA ACTA. - ISSN 0040-6031. - 430:1-2(2005), pp. 95-99. [10.1016/j.tca.2004.12.010]
Solidification of metallic tin in dispersed phase
BONICELLI, Maria Grazia;
2005
Abstract
Differential scanning calorimetry (DSC) and particle size measurements were carried out on disproportionation products of pure SnO to investigate the fusion and solidification behaviour of Sn droplets and their catalytic nucleation on Sn oxides. If disproportionation reaction takes place at T >= 798 K, the products are metallic Sn and SnO2; but for 523 < T < 798 K, SnO2 is replaced by an intermediate oxide (IO) SnxO(1+x). On melting, samples with 10 show a drop of melting point of metallic tin due to Gibbs-Thomson effect; no lowering of melting point was observed in samples with SnO2. On the other hand, if solidification occurs in the presence of IO, Tin droplets always displayed three distinct exothermic solidification peaks, but if it takes place in the presence of SnO2, only one exothermic peak is observed. Undercooling values and contact angles were determined for each of the heterogeneous nucleation processes. The different behaviour of metallic Tin droplets was related to the different lattice symmetry of SnO2 and IO, which act as nucleation catalysts. (c) 2004 Elsevier B.V. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
