Temperature Dependence of The Raman Frequency Shifts Related to The Specific Heat and Thermal Expansion Close To I-II Phase Transition in S-Triazine.

A linear variation of the specific heat C-p with the frequency shifts 1/omega(partial derivative omega/partial derivative T)(p) is established for the Raman modes I-V at various temperatures (P=0) close to I-II phase transition in s-triazine (T-c=198 K). As an extension of this work, the temperature dependence of the thermal expansion alpha(p) is predicted from the frequency shifts and by the gamma(p) values deduced for the Raman modes studied close to the I-II phase transition in s-triazine. Our predicted alpha(p) can be examined by the thermodynamics measurements of the thermal expansion at various temperatures at zero pressure in both phases I and II of s-triazine.