Calculating phase diagrams (Calphad) I am calculating the phase diagrams for Li-Mg binary alloy with reference to the following text:
http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=5600701
In the equation used in the above paper, i am confused about whether G0 for a component is a function of temperature?

 A: Yes, the various $G^0$s are a function of temperature.  One can look up the generally accepted values in the SGTE Data for Pure Elements, by A. T. Dinsdale (google it - you can probably find the pdf on line). 
Usually, when doing the calculation, you select a reference state for the elements in your phase diagram, here most likely being $\mathrm{BCC}_\mathrm{A2}$ Lithium, and $\mathrm{HCP}_\mathrm{A3}$ Magnesium.  Then, you can ignore the temperature variations of those.  However, for the other elemental phases the SGTE compilation will give formulas detailing the additional free energy of that phase over the reference phase. 
The RT term is the entropy of mixing, the summation is the (usually) standard Redlich-Kister form. (Note that some older papers have an expression that looks similar, but isn't).
A glance at the Li-Mg diagram indicates no alloy phases, and no elemental phase transitions over the range of interest, so you can safely ignore the $G^0$ values unless you are trying to calculate absolute free energies with respect to some other element you have not mentioned.
