Changes in the superconducting temperature by pressure in Nb$_{3}$Sn and its influence in the martensitic transition.

High pressure experiments performed in a Nb$_{3}$Sn single crystal shows changes on the superconducting temperature and in the martensitic transition. Specific heat measurements performed in this crystal shows an anomaly at about 50 K associated to the martensitic transition. At ambient pressure, the electrical resistivity as a function of temperature shows a T$_{C}$ of 18.7 K with a transition width $\Delta $T$_{C}$ (10 to 90 {\%}) of 0.7 K. At low temperatures the R vs T curve show a T$^{2}$ behavior, specifically in the temperature range from 52 down to 23 K. The superconducting transition temperature decreases in linear form with a rate dTc/dP = - 0.79 K/GPa. The results are discussed in terms of the pressure effects on the martensitic transition via changes in the density of electronic states.