THE ACTIVATION ENERGY FOR THE SUBLIMATION OF GALLIUM NITRIDE (thesis)

Gallium nitride was found to sublime congruently from a torsion—effusion cell when the ratio of orifice area to sample area was about 1/30 and incongruently to yield nitrogen gas and liquid gallium when this ratio was about 1/100 or less. A mass‐spectrometer investigation revealed no measurable concentrations of gallium nitride vapor molecules. The heat of activation for the reaction 2GaN(s)=2Ga(1)+N2(g) was calculated to be 39 kcal at 1300°K from the temperature dependence of the effusion data.The rate of the reaction 2GaN(s)=2Ga(g)+N2(g) was measured by a torsion—Langmuir method. From the temperature dependence of sublimation the heat of activation for this reaction was calculated to be ΔH1300‡=218.6 kcal compared to 173 kcal for the equilibrium reaction, and the entropy of activation was calculated to be 74.3 cal/deg.

[1]  Z. A. Munir,et al.  Torsion Effusion Study of the Vapor Pressure and Heat of Sublimation of Gallium , 1964 .

[2]  R. Hultgren,et al.  Selected Values of Thermodynamic Properties of Metals and Alloys , 1963 .

[3]  C. D. Thurmond,et al.  THE PRESSURE OF Ga2O OVER GALLIUM-Ga2O3 MIXTURES , 1962 .

[4]  L. M. Foster,et al.  Vapor Pressure of Gallium, Stability of Gallium Suboxide Vapor, and Equilibria of Some Reactions Producing Gallium Suboxide Vapor , 1962 .

[5]  J. Hirth,et al.  Evaporation of Metal Crystals , 1957 .

[6]  J. Margrave,et al.  Gaseous Metal Nitrides. II. The Vapor pressure Of GaN(S) And Evidence For A Complex Gaseous Nitride , 1956 .

[7]  J. Margrave,et al.  Gaseous Metal Nitrides. I. Theoretical Dissociation Energies for Diatomic Nitrides , 1955 .

[8]  J. Margrave.  Thermodynamic calculations. I: Using free-energy functions and heat-content functions , 1955 .

[9]  J. H. Freeman,et al.  Alkaline-catalyzed Reaction of Formaldehyde and the Methylols of Phenol; A Kinetic Study1 , 1954 .

[10]  Rustum Roy,et al.  Polymorphism of Ga2O3 and the System Ga2O3—H2O , 1952 .

[11]  R. Juza,et al.  Untersuchungen über die Nitride von Cadmium, Gallium, Indium und Germanium. Metallamide und Metallnitride. VIII. Mitteilung , 1940 .

[12]  Henry Eyring,et al.  The Deduction of Reaction Mechanisms from the Theory of Absolute Rates , 1937 .

[13]  M. Lorenz,et al.  Preparation, Stability, and Luminescence of Gallium Nitride , 1962 .

[14]  R. Littlewood,et al.  On the evaporation coefficient , 1956 .

[15]  W. C. Johnson,et al.  Nitrogen Compounds of Gallium. III , 1931 .