A switch-over model of periodic structure formation in ternary diffusion couples

The mechanism of periodic layer formation during solid-state reaction between Mg and SiO2

“…At the reaction front close to the SiO 2 substrate, we found a narrow transition zone that has not been reported in the previous studies [7][8][9]. The transition zone is more prominent on the polished sample inlaid in the resin than on the sample left unpolished prior to SEM investigations (Fig.…”

“…In 2001, Klinger et al [8] proposed a switch-over model to explain the formation mechanism for the reaction system Mg/ SiO 2 . This model was similar to the chemical-potential-instability model proposed by Kao and Chang [4] in 1993.…”

“…Since its discovery by Osinski et al in 1982, a number of systems have been reported that display regularly spaced layers of reaction products including systems such as Zn/Fe 3 Si, Zn/Co 2 Si, Zn/Ni 3 Si 2 , Mg/Ni 50 Co 20 Fe 30 , Ni/SiC, Pt/SiC, Co/SiC, Mg/SiO 2 , Zn/Ni 3 Si and Al/U 10 Mo [1][2][3][4][5][6][7][8][9][10][11]. The research work focusing on this phenomenon is not only a matter of curiosity, but it is also relevant to fundamental studies of reactive diffusion [12][13][14][15][16][17][18][19] and it might even find applications in areas such as in situ compositional modulation of Mg 2 Si-based thermoelectric materials intended for either cooling or harvesting of waste industrial heat.…”

“…Although several different models have been put forward to explain the formation of periodic layered structures in the reactive diffusion process [1][2][3][4][5][6][7][8][9], the exact nature of the reaction mechanism remains a controversial topic. In 2003, Chen et al [20] proposed the diffusion-induced stresses model to explain the formation mechanism and gave the general quantitative description applicable to periodic layered structures.…”

“…Although the model explained successfully the important experimental features observed in several reaction systems such as Zn/Fe 3 Si, Zn/Co 2 Si and Pt/SiC [20][21][22], it could not address the formation mechanism in the interesting Mg/SiO 2 system because of the acute scarcity of experimental details concerning the layers' microstructure [9]. The periodic layer formation during the reaction between Mg and SiO 2 was first reported in 2001 by Gutman et al [7] and, subsequently, a switch-over model and its modifications were proposed in 2001 and 2006 to explain the formation mechanism for this reaction system [8,9]. In this paper, we provide a detailed account of the periodic layer formation in the Mg/SiO 2 system based on our high-resolution field-emission SEM investigations and based on these observations we offer clarification of the controversial pattern formation mechanisms.…”