Thermochimica Acta 404 (2003) 289–290 Short communication Note on the use of the term “crystolysis” Tong B. Tang a,* , Marek Maciejewski b a NanoTech Institute, Universityof Texas at Dallas, Richardson, TX 75083-0688, USA b Institute of Chemical and Bioengineering, Swiss Federal Institute of Technology, ETH Hönggerberg, CH-8093 Zurich, Switzerland Received 24 February 2003; received in revised form 24 February 2003; accepted 24 March 2003 Recently, Galwey and Vyazovkin have been en- gaged in a debate over the significance, for the ki- netics of a solid state reaction, of apparent activation energy that varies continuously with α, the degree of reactant conversion [1–3]. Such discussions will, in our belief, contribute greatly to a healthy development of solid-state kinetic analysis away from the emphasis on empirical or numerical data fitting. This development will surely take years. Here, we wish to raise a minor point that may, however, be non-trivial, namely the word “crystolysis” that made to the title of Galwey’s paper [2], from its origin as one possibility for the index reference for the decom- position of solids [4]. We suggest that such terminology is inappropriate, based on two reasons. Our first object is philological. The expressions py- rolysis or thermolysis, photolysis, radiolysis and hy- drolysis have always denoted decompositions by heat, light, ionizing radiation and water, respectively. Per- haps we may also talk of electrolysis of a solid elec- trolyte by current and “dielectrolysis” of an insulator by electric field. Such nice convention would be bro- ken if then “crystolysis” referred to a decomposition in which the reactant or one or more of the reactants belong to crystalline phases. Well, frontolysis does in- * Present address: Physics Department, H.K. Baptist University, Kowloon, Hong Kong SAR, China. Tel.: +852-34117036; fax: +852-34115813. E-mail address: tbtang@hkbu.edu.hk (T.B. Tang). deed stand for the dissolution of a weather front, but that is in the less precise science of meteorology! The other objection is scientific, and therefore more fundamental. Although a reactant starts as a single crystal or as a polycrystalline sample, its decomposi- tion may not, on the atomic level, proceed in an or- dered lattice. At active sites on a free surface, or on an interface between the reactant and an reaction prod- uct, the atoms may suffer so severe a disorder that the theoretical description of their rearrangement be- comes easier if they are treated as amorphous. A crys- tal may not decompose as a crystal! The peculiarities in the kinetics of such reactions, f(α), may derive sim- ply from the geometrical constraints on the surface or interface, an example being the melting of ice, as Gal- wey et al. have themselves shown [5]. Prior to a con- clusive study on a particular solid-state decomposition we cannot tell how “crystalline” is its decomposition mechanism, so we should not apply to it any a priori label “crystolysis”. We note that, besides Galwey in several of his pub- lications, L’vov has also employed the title term [6]. On the other hand, the same term has also invoked for “an early sign of hypoxia in the mitochondria” [of a cell] by biologists, in a paper [7] entitled “Diagno- sis of myocardial ischaemia by epicardial detection of potassium ion activity,” or whatever that means. For- tunately, a fight over the right to definite this term seems unnecessary. In summary, “crystolysis” is inappropriate because all the other “-olysis” characterize atomic rearrange- ment phenomena occurring under various influences, 0040-6031/$ – see front matter © 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0040-6031(03)00187-4