SIMULTANEOUS ASSESSMENT OF THE YBA2CU3O6+Z THERMODYNAMICS UNDER THE LINEAR ERROR MODEL

About 3000 experimental points obtained in 220 miscellaneous experimen ts published in 57 papers have been processed simultaneously in order to obtain the most reliable Gibbs energy of the YBa2Cu3O6+z solid solu tion in the temperature range from 250 to 1300 K. A part of this solut ion is well-known as the ''Hi-T-c Y123'' phase. All other thermodynami c properties of the solution including the conditions for the tetragon al-orthorhombic phase transition and the miscibility gap at lower temp eratures, are derived from the assessed Gibbs energy. The linear error model introduced recently by one of the authors has been employed for the simultaneous assessment, The results obtained are compared with t hose of the conventional weighted least squares method and the benefit of the new approach is discussed. Another problem in simultaneous ass essment that is also considered is visualizing the quality of the fit. New types of graphs (partly based on the linear error model) that fac ilitate visualizing the quality of the fit are presented. (A critical review with 72 references.) (C) 1998 American Institute of Physics and American Chemical Society. [S0047-2689(98)00404-8].