Thermochimica Acta 484 (2009) 70–76 Contents lists available at ScienceDirect Thermochimica Acta journal homepage: www.elsevier.com/locate/tca On the glass-crystal transformation kinetics by using differential scanning calorimetry under non-isothermal regime Application to the crystallization of the Ag 0.16 As 0.46 Se 0.38 semiconductor glass J.L. Cárdenas-Leal, J. Vázquez ∗ , D. García-G. Barreda, P.L. López-Alemany, P. Villares, R. Jiménez-Garay Departamento de Física de la Materia Condensada, Facultad de Ciencias, Universidad de Cádiz, Apartado 40, 11510 Puerto Real (Cádiz), Spain article info Article history: Received 24 March 2008 Received in revised form 5 November 2008 Accepted 30 November 2008 Available online 9 December 2008 PACS: 61.40 64.40.Qb 64.70.Kb 64.70.Pf Keywords: Amorphous materials Glass-crystal transformation Impingement effect Differential scanning calorimetry Reheating treatment Thermal analysis abstract A procedure has been developed to obtain an evolution equation with the temperature for the actual transformed volume fraction under non-isothermal regime, to calculate the kinetic parameters and to analyze the glass-crystal transformation mechanisms in solid systems where a large number of nuclei already exists and no other new nuclei are formed during the thermal treatment. In this case, it is assumed that the nuclei only grow, “site saturation”, during the thermal process. Once an extended volume of transformed material has been defined and spatially random transformed regions have been assumed, a general expression of the extended volume fraction has been obtained as a function of the temperature. Considering the mutual interference of regions which grow from separate nuclei (impingement effect) and from the quoted expression, the actual transformed volume fraction has been deduced. The kinetic parameters have been obtained, by assuming that the reaction rate constant is a time function through its Arrhenian temperature dependence. The developed theoretical method has been applied to the crystal- lization kinetics of the Ag 0.16 As 0.46 Se 0.38 glassy alloy as-quenched and previously reheated. In accordance with the corresponding results, it is possible to establish that in the considered alloy the nuclei were dom- inant before the thermal treatment, and because of it the reheating does not change in a considerable way the number of the pre-existing nuclei in the material, which is a case of “site saturation”. The comparison of the quoted results with the values obtained by means of Matusita method confirms the reliability of the theoretical method developed (TMD). Moreover, the obtained values for the kinetic parameters coincide in a satisfactory way with the results calculated by means of the Austin–Rickett (AR) equation under non- isothermal regime. Besides, the experimental curve of the transformed fraction shows a better agreement with the theoretical curves of the developed method and of the Austin–Rickett model than with the cor- responding curve of the Avrami model. Accordingly, it seems appropriate to choose the Austin–Rickett equation in order to describe the crystallization mechanism of the above-mentioned glassy alloy. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Traditionally, solid-state physics has meant crystal physics. Solidity and crystallinity have been considered as synonymous in texts on condensed matter. However, at present one of the most active fields of solid-state research is the study of solids that are not crystals, solids in which the arrangement of the atoms lacks the slightest vestige of long-range order. Solid-state phase transforma- tions play an important role in the production of many materials. Therefore, the last decades have seen the strong impulse that research community has given at the study of a general descrip- tion of the kinetics of phase transformations [1] and accordingly, during the last 60 years the theoretical and practical interest in the ∗ Corresponding author. E-mail address: jose.vazquez@uca.es (J. Vázquez). application of calorimetric analysis techniques to the study of the quoted transformations has notably increased [2–4]. Thus, the for- mal theory of nucleation and crystal growth has been developed during the last half century with the notable work performed by Christian [5] and a relatively recent review published by Kelton [6]. The calorimetric analysis techniques are quick and need small quantities of glass samples to obtain the kinetic parameters of a transformation. There are two thermal analysis regimes: isothermal and non-isothermal. The first one is in most cases more accu- rate and the data can be interpreted by the Johnson–Mehl–Avrami (JMA) equation [7–10], however, the non-isothermal thermoana- lytical methods have several advantages. The rapidity with which non-isothermal experiments can be performed makes this type of experiments more attractive. Moreover, the industrial processes often depend on the kinetic behaviour of systems undergoing phase transformations under non-isothermal conditions. Accord- ingly, the use of non-isothermal techniques to study solid-state 0040-6031/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.tca.2008.11.014