\chapter{Investigation of self-constructed 3C-SiC precipitates}
\section{3C-SiC precipitate in crystalline silicon}
+\label{section:const_sic:prec}
+
+{\color{red}Todo: Phase stability as Kai Nordlund proposed (120 Tm simulations).}
A spherical 3C-SiC precipitate enclosed in a c-Si surrounding is constructed as it is expected from IBS experiments and from simulations that finally succeed in simulating the precipitation event.
On the one hand this sheds light on characteristic values like the radial distribution function or the total amount of free energy for such a configuration that is aimed to be reproduced by simulation.
Investigating the radial distribution function shown in figure \ref{fig:md:pc_500-fin}, which shows configurations below and above the temperature of the estimated transition, indeed supports the assumption of melting gained by the free energy plot.
However the precipitate itself is not involved, as can be seen from the Si-C and C-C distribution, which essentially stays the same for both temperatures.
Thus, it is only the c-Si surrounding undergoing a structural phase transition, which is very well reflected by the difference observed for the two Si-Si distributions.
-This is surprising since the melting transition of plain c-Si is expected at temperatures around 3125 K, as discussed in the last section.
+This is surprising since the melting transition of plain c-Si is expected at temperatures around 3125 K, as discussed in section \ref{subsection:md:tval}.
Obviously the precipitate lowers the transition point of the surrounding c-Si matrix.
+This is indeed verified by visualizing the atomic data.
+% ./visualize -w 640 -h 480 -d saves/sic_prec_120Tm_cnt1 -nll -11.56 -0.56 -11.56 -fur 11.56 0.56 11.56 -c -0.2 -24.0 0.6 -L 0 0 0.2 -r 0.6 -B 0.1
+\begin{figure}[!ht]
+\begin{center}
+\begin{minipage}{7cm}
+\includegraphics[width=7cm,draft=false]{sic_prec/melt_01.eps}
+\end{minipage}
+\begin{minipage}{7cm}
+\includegraphics[width=7cm,draft=false]{sic_prec/melt_02.eps}
+\end{minipage}
+\begin{minipage}{7cm}
+\includegraphics[width=7cm,draft=false]{sic_prec/melt_03.eps}
+\end{minipage}
+\end{center}
+\caption{Cross section image of atomic data gained by annealing simulations of the constructed 3C-SiC precipitate in c-Si at 200 ps (top left), 520 ps (top right) and 720 ps (bottom).}
+\label{fig:md:sic_melt}
+\end{figure}
+Figure \ref{fig:md:sic_melt} shows cross section images of the atomic structures at different times and temperatures.
+As can be seen from the image at 520 ps melting of the Si surrounding in fact starts in the defective interface region of the 3C-SiC precipitate and the c-Si surrounding propagating outwards until the whole Si matrix is affected at 720 ps.
+As predicted from the radial distribution data the precipitate itself remains stable.
+
For the rearrangement simulations temperatures well below the transition point should be used since it is very unlikely to recrystallize the molten Si surrounding properly when cooling down.
To play safe the precipitate configuration at 100 \% of the Si melting temperature is chosen and cooled down to $20\,^{\circ}\mathrm{C}$ with a cooling rate of $1\,^{\circ}\mathrm{C}/\text{ps}$.
-{\color{blue}Todo: Wait for results and then compare structure (PC) and interface energy, maybe a energetically more favorable configuration arises.}
-{\color{red}Todo: Mention the fact, that the precipitate is stable for eleveated temperatures, even for temperatures where the Si matrix is melting.}
-{\color{red}Todo: Si starts to melt at the interface, show pictures and explain, it is due to the defective interface region.}
+However, an energetically more favorable interface is not obtained by quenching this structure to zero Kelvin.
+Obviously the increased temperature run enables structural changes that are energetically less favorable but can not be exploited to form more favorable configurations by an apparently yet too fast cooling down process.
\section{Coherent to incoherent transition of 3C-SiC precipitates in crystalline silicon}
-Results of the defect ... indicate the very likely possibility of another precipitation mechanism.
+As already pointed out, some of the previous results indicate the very likely possibility of another precipitation mechanism.
This mechanism is based on the successive formation of substitutional C sites, which might result in coherent 3C-SiC structures within the c-Si matrix assuming that Si self-interstitials might diffuse out of the affected region easily.
-Reaching a critical size these coherent precipitates release the alignement on the c-Si lattice spacing by contracting to an incoherent SiC precipitate with lower lattice constant.
+Reaching a critical size these coherent SiC structures release the alignement on the c-Si lattice spacing by contracting to an incoherent SiC precipitate with lower lattice constant.
Precipitation -> contraction ... free 'space' might be compensated by volume changes due to the barostat ...
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