The heat capacity, and other properties (table 2), were measured between 18 and 305K. It was noted that the heat capacity, at the lowest temperatures studied, did not exhibit the T2 temperature-dependence which tended to be typical of substances having a layered structure. The entropy at 298.16 was 8.60cal/deg.mol.

Low-Temperature Heat Capacities of Magnesium Diboride (MgB2) and Magnesium Tetraboride (MgB4). R.M.Swift, D.White: Journal of the American Chemical Society, 1957, 79, 3641-4