SPECIFIC-HEAT AND MAGNETIC-ORDERING IN CUO SINGLE-CRYSTALS

We present measurements of the specific heat of single crystalline cupric oxide, CuO, in the temperature range 1.8 K to 1000 K and confirm the first order transition at T1 = 213.8 ± 0.3 K and the second order anomaly (antiferro magnetic transition) at TN = 229.8 ± 0.3 K, earlier found for powdered samples. Above 230 K, the specific heat contains significant magnetic contributions which decrease only above 700 K. Copper oxide displays the characteristic features of a one or two dimensional Heisenberg antiferromagnets. At low temperatures, the single crystal follows a T - law (Θo = 391 + 10K ). The thermodynamic standard values at 298.16 K are given. © 1990.