The thermodynamic properties of SrBaFe4O8(s) from T -> 0 to T=1500 K

The low-temperature adiabatic heat capacity of SrBaFe4O8(s) has been measur ed from T = 4 K to T = 420 K, yielding for C-p,m(0) and S-m(0) at T = 298.1 5 K, the values (288.9+/-0.3) J . K-1 . mol(-1) and (338.0+/-0.3) J . K-1 . mol-1, respectively. The enthalpy increment function for the above ambient temperature has been obtained from high-temperature drop calorimetry measu rements over the temperature range 525 K to 882 K. In addition, the standar d molar enthalpy of formation has been derived from the standard molar enth alpies of solution in (2.65 mol . dm(-3) HCl + 1.76 mol . dm(-3) HNO3)(aq) using an isoperibol solution calorimeter. From these measurements and auxil iary data, the following value has been obtained: Delta(f)H(m)(0)(298.15 K) {SrBaFe4O8(s)} = -(2888.0 +/- 5.0) kJ . mol(-1). A table containing the the rmodynamic properties at selected temperatures from 298.15 K to 1500 K is g iven. (C) 2000 Academic Press.