Volume relaxation of amorphous selenium (a-Se) was studied by mercury dilatometry. Two differently constructed dilatometers (different sensitivity of sample volume change and different values of characteristics time constants of the dilatometers) were used to study the influence of experimental setting on the relaxation measurements. Temperature of glass transition and thermal expansion coefficients in glassy and undercooled liquid state were determined from nonisothermal experiments. Four sets of isothermal experiments including temperature down-jump, up-jump and combined experiments were performed to study the volume relaxation. The Tool-Narayanaswamy-Moynihan model was applied to describe the relaxation behavior of a-Se. All four sets of isothermal experiments were described using one set of TNM parameters. The combined experiments were considered to be most suitable for studying the structural relaxation because of the minimum of the information lost at the beginning of the experiment. The reaction of a-Se and mercury was found not ot be influencing the results of volume relaxation measurements.
