Nanoobjects microscopy

Kinetics of layer, island and dendrite polymorphous crystallizations of amorphous films, deposited by laser ablation
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

The concepts of layer polymorphic crystallization (LPC), island polymorphic crystallization (IPC) and dendrite polymorphic crystallization (DPC) are formed [1]. For each crystallization mode the parameter of dimensionless relative unit of length δ0, equal to the ratio of the characteristic unit of length to the value, characterizing the size of the unit cell of the crystal, was respectively assigned. Kinetic curves of the dependence of the fraction of the crystalline phase x on time t are given.
LPC (Cr2O3, V2O3, Sb2S3, Se and others) is regarded as morphological analog of Frank–van der Merwe (FM) growth mode of a crystal from the vapor phase. In the case of LPC in the zone of observation in amorphous film grows a single flat crystal. By analogy with FM growth mode an energy criterion of the LPC can be written as σa≥σc+σac+εd, where σa is the free energy of the amorphous phase–vacuum interface, σc is the free energy of the crystalline phase–vacuum interface, σac is the free energy of the amorphous–crystalline phase interface, and εd is the energy of deformation of the growing crystalline layer. For LPS the quadratic dependence of x on t takes place and δ0~ 3000-5000.
IPC (Al2O3, ZrO2, Ni, Re and others) is regarded as morphological analog of Volmer–Weber (VW) growth mode of a crystal from the vapor phase. In the case of IPC in the zone of observation in amorphous film grows a lot of small disoriented crystals. By analogy with VW growth mode an energy criterion of the IPC can be written as σa≤σc+σac+εd. For IPS the exponential dependence of x on t takes place and δ0~ 100-900.
DPC (HfO2 and others) is regarded as morphological analog of Stranski–Krastanov (SK) growth mode of a crystal from the vapor phase. A characteristic sign of DPC is the formation of dendrite branches along the sides of a flat single crystal. For DPC the quadratic dependence of x on t takes place and δ0~ 3000.

1.	Bagmut A.G. Structural and morphological features of crystallization reactions of amorphous films according to the electron microscopy data // Functional Materials.-2012.-19.-P. 370-377.