THERMODYNAMIC ANALYSIS OF YBA2CU3O7-X

The thermodynamic properties of YBa2Cu3O7-x for 0 < x < 0.2 have been reviewed. At 298 K the following values were determined: c(p) = 295.4 J/(mol . K), S298-degrees = 326.5 J/(mol . K) and DELTA(f)H298-degrees = -2711 kJ/mol. Thermodynamic data for the specific heat were approxi mated by the following polynomials: c(p) = 2.914 . 10(2) + 1.596 . 10( -1) T-1.084 . 10(-4) T2 -3.09 . 10(6) c(p) in J/(mol . K) in the tempe rature range of 298 to 342 K and c(p) 3.037. 10(2) + 6.639. 10(-2) T-2 .286 . 10(6) T-2 in J/(mol . K) in the temperature range of 342 to 129 3 K. The influence of oxygen deficiency on the thermodynamic propertie s can be approximated by DELTA(f)H298-degrees = -2711 + 77.578 . x + 1 .202 . x2 (kJ/mol) S298-degrees = 326.5 - 4.1 . x (J/(mol . K)).