Oberleutenant Audit. Pfaff with Three Teachers from Radochonce Portraits; Groups

Bernhard Bardach World War I Album I

Participants in the Merzig Synagogue Festival Portraits Groups

Verso: "Merziger Synagoguenfest ca. 1922"

Unidentified Group at Swimming Pool; Pioneer Youth Camp Portraits Groups

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Ernst Mathias with military doctors, nurses and patients Military; World War I; Portraits; Groups

Feldpost to wife Emmy Mathias; September 19, 1918

Discussion of enthalpy, entropy and free energy of formation of GaN

Presented in this letter is a critical discussion of a recent paper on experimental investigation of the enthalpy, entropy and free energy of formation of gallium nitride (GaN) published in this journal [T.J. Peshek, J.C. Angus, K. Kash, J. Cryst. Growth 311 (2008) 185-189]. It is shown that the experimental technique employed detects neither the equilibrium partial pressure of N-2 corresponding to the equilibrium between Ga and GaN at fixed temperatures nor the equilibrium temperature at constant pressure of N-2. The results of Peshek et al. are discussed in the light of other information on the Gibbs energy of formation available in the literature. Entropy of GaN is derived from heat-capacity measurements. Based on a critical analysis of all thermodynamic information now available, a set of optimized parameters is identified and a table of thermodynamic data for GaN developed from 298.15 to 1400 K.

Kurt Hirschfeld (left) speaking with Thomas Mann Portraits Groups Men

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