Nanoobjects microscopy

Structural and kinetic aspects of island polymorphous crystallizations of amorphous films
Bagmut A.G., Bagmut I.A.
Department of Physics of the National Technical University “Kharkiv Polytechnic Institute” of Ukraine. NTU “KhPI” 2, Kyrpychova str., 61002, Kharkiv, Ukraine.
E-mail: agbagmut@gmail.com

Data, reflecting island polymorphous crystallization of amorphous films of ZrO2, V2O3 and Yb2O2S, are presented. Crystallization of amorphous films was studied by the TEM methods “in situ” with video registration of structural changes. Kinetic curves, demonstrating the dependence on time of the crystals density n(t) and of the fraction of the crystalline phase x(t) was obtained with the help of frame-by-frame analysis of the video [1]. The formation of the polycrystalline films takes plase in accordance with α and β-versions of the Kolmogorov's model [2]. In this kase x=1-exp(-ntk), where k is the Avrami coefficient and n is an effective rate constant, describing both nucleation and growth. The value of relative length δ0=D0Ω-⅓, where D0 is the characteristic unit of length and Ω is the volume of the unit cell of the growing crystal, is a few hundred (table 1). At small layer thicknesses of films, the effect of stabilization of the amorphous state was observed.
Table 1. Parameters of the electron beam crystallization of amorphous films*
Parameter	Yb2O2S, this work
(α-version of the K-model)	V2O3
(α-version of the K-model)	ZrO2
(β-version of the K-model)	
α, cm–2·s–1	3.93·108	9.38·108	-	
β, cm−2	-	-	1.4·1010	
k	1.8	2.0	1.3	
δ0	1030	949	118	
*α is the intensity of nucleation of crystallization centers, β is the density of crystallization nuclei, k is the Avrami coefficient, δ0 is the relative length.
1.	Bagmut A. G., Bagmut I. A. Modes and kinetics of crystals growth in amorphous films of oxides // Molecular Crystals and Liquid Crystals.- 2018.- 673, P. 120-124.
2.	Kolmogorov A. N. On the statistical theory of crystallization of metals // Izv. Acad. Sci. USSR, Ser. Math.- 1937.- 1, P. 355-359 [in Russian].