  We study the thermodynamic quantities such as the Helmholtz free energy, the
mean energy and the specific heat for both the Klein-Gordon, and Dirac
equations. Our analyze includes two main subsections: ($i$) statistical
functions for the Klein-Gordon equation with a linear potential having Lorentz
vector, and Lorentz scalar parts ($ii$) thermodynamic functions for the Dirac
equation with a Lorentz scalar, inverse-linear potential by assuming that the
scalar potential field is strong ($A \gg 1$). We restrict ourselves to the case
where only the positive part of the spectrum gives a contribution to the sum in
partition function. We give the analytical results for high temperatures.
