  Structural investigation on $Co_{3-x}Mn_xTeO_6$; ($0 \lt x \le 2$) solid
solutions as a function of Mn concentration using Synchrotron X-ray diffraction
(SXRD) and XANES measurements are presented. Phase diagram obtained from
Rietveld Refinement on SXRD data as a function of Mn concentration indicates
doping disproportionate mixing of both monoclinic (C2/c) and rhombohedral (R-3)
structure (for $x \lt 0.5$) while only R-3 symmetry for $x \ge 0.5$.
Furthermore, Rietveld analysis on SXRD data shows increase in lattice
parameters and average transition metal oxygen (Co/Mn-O) bond lengths for $x
\ge 0.5$. Co and Mn K-edge XANES spectra reveal that both Co and Mn are in
mixed oxidation state of $Co^{2+}/Mn^{2+}$ and $Co^{3+}/Mn^{3+}$. Relative
ratio of $Co^{3+}/Co^{2+}$ and $Mn^{3+}/Mn^{2+}$ using Linear combination fit
(LCF) decrease with increasing $x$ for $x \ge 0.5$. These structural and
spectroscopic evidences are used to provide possible interpretation of the
reported observations of maximum Neel Temperature (TN) at $x ~\sim 0.5$ and
enhancements of antiferro/ferro-magnetic interactions in $Co_{3-x}Mn_xTeO_6$
solid solutions.
