  We report a Raman scattering investigation of multiferroic bismuth ferrite
BiFeO3 epitaxial (c-axis oriented) thin films from -192 to 1000C. Phonon
anomalies have been observed in three temperature regions: in the gamma-phase
from 930C to 950C; at ~370C, Neel temperature (TN), and at ~123C, due to a
phase transition of unknown type (magnetic or structural). An attempt has been
made to understand the origin of the weak phonon-magnon coupling and the
dynamics of the phase sequence. The disappearance of several Raman modes at
~820C (Tc) is compatible with the known structural phase transition and the
Pbnm orthoferrite space group assigned by Arnold {\it et al.} \cite{arnold:09}.
The spectra also revealed a {\it non-cubic} $\beta$-phase from 820-930\dc and
the same {\it non-cubic} phase extends through the $\gamma$-phase between
930-950\dc, in agreement with Arnold {\it et al.} \cite{arnold2:09}, and an
evidence of a cubic $\delta$-phase around 1000\dc in thin films that is not
stable in powder and bulk. Such a cubic phase has been theoretically predicted
in \cite{vasquez:prb09}. Micro-Raman scattering and X-ray diffraction showed no
structural decomposition in thin films during the thermal cycling from
22-1000\dc.
