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Rapid sorption processes on granular zeolite
120
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
Vol. i, No. 5
GaAs samples. On (iLl) surfaces of n-type GaAs, quasi-equilibrium measurements are possible at very low frequencies, and a surface conductance minimum can be observed. From this the existence of acceptor levels, to a large extent bulk states~ can be concluded. From optical measurements three levels (1.09 eV, 0.88 eV, 0.73 eV) can be deduced at room temperature. A second quasi-equillbrium situation with much larger relative conductance changes exists at high frequencies (around 8 kc/sec) where the surface appears to be n-type. The slow bulk trapping has been investigated more directly with dc measurements, and results concerning trapping times and temperature dependences are presented. On p-type samples with (110) surfaces, evidence for slow surface states, which are ambient-dependent, similar to those of Ge surfaces, has been found. (Received 12 August 1963)
ii. ON THE REGION OF INDIFFERENCE FOR HIGH PRESSURE TRANSITIONS IN d-CAMPHOR (II-III) AND P H O ~ O R U S
(I-II).
A.F. Gabrysh, H. Eyrlng & A. Van Hook (Institute for the Study of Rate Processes and Department of Metallurgy, University of Utah, Salt Lake City, Utah, U.S.A.). An investigation has been made of the effect of pressure on the transformation in d-camphor and phosphorus. The so-called "region of indifference", reported as approximately 0.6 kbars in camphor and approximately 0.38 kbars in phosphorus, was found to be less than O.14 kbars and 0.16 kbars, respectively. Rates of transformation between phases showed strong dependence on the purity of material, and it is suggested that for sufficiently high purity the region of indifference may become vanishingly small. (Received 16 May 1963; in revised form 13 August 1963)
12. RAPID SORPT!ON PROCESSES ON GRANULAR ZEOLITE.* W.W. Brandt & W. Rudloff (Department of Chemistry, Illinois Institute of Technology, Chicago 16, Illinois, U.S.A.). The rates of sorption of several gases on chabazite, a natural zeolite, have been measured, using a constant volume system and automatic recording of pressure changes. The relevant solutions of the diffusion equation are computed and tabulated, and are used to analyze the sorption processes from essentially zero to infinite time.
The sorption of carbon dioxide appears to be controlled by a slow adsorption step, but the data obtained for methane and argon can best be explained by assuming the natural crystals either to contain grain boundaries of high permeability, or to be traversed by relatively thin shells of compact and probably amorphous material of low permeability. The possible effects of the grain shape irregularity and size distribution have been explored. (Received 7 Ms~ 1963; in revised form 13 August 1963)
13. SEMICONDUCTION AND CATION VALENCIES IN MANGANESE FERRITES. F.K. Lotgering (Fhilips Research Laboratories, N.V. Philips' Gloeilampenfabrieken, Eindhoven, The Netherlands). *Abstracted in part from work done by W. Rudloff in partial fulfi11-~ut of the research requirement for the Ph.D. degree in the Department of Chemistry at Illinois Institute of Technology.
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
Vol. i, No. 5
GaAs samples. On (iLl) surfaces of n-type GaAs, quasi-equilibrium measurements are possible at very low frequencies, and a surface conductance minimum can be observed. From this the existence of acceptor levels, to a large extent bulk states~ can be concluded. From optical measurements three levels (1.09 eV, 0.88 eV, 0.73 eV) can be deduced at room temperature. A second quasi-equillbrium situation with much larger relative conductance changes exists at high frequencies (around 8 kc/sec) where the surface appears to be n-type. The slow bulk trapping has been investigated more directly with dc measurements, and results concerning trapping times and temperature dependences are presented. On p-type samples with (110) surfaces, evidence for slow surface states, which are ambient-dependent, similar to those of Ge surfaces, has been found. (Received 12 August 1963)
ii. ON THE REGION OF INDIFFERENCE FOR HIGH PRESSURE TRANSITIONS IN d-CAMPHOR (II-III) AND P H O ~ O R U S
(I-II).
A.F. Gabrysh, H. Eyrlng & A. Van Hook (Institute for the Study of Rate Processes and Department of Metallurgy, University of Utah, Salt Lake City, Utah, U.S.A.). An investigation has been made of the effect of pressure on the transformation in d-camphor and phosphorus. The so-called "region of indifference", reported as approximately 0.6 kbars in camphor and approximately 0.38 kbars in phosphorus, was found to be less than O.14 kbars and 0.16 kbars, respectively. Rates of transformation between phases showed strong dependence on the purity of material, and it is suggested that for sufficiently high purity the region of indifference may become vanishingly small. (Received 16 May 1963; in revised form 13 August 1963)
12. RAPID SORPT!ON PROCESSES ON GRANULAR ZEOLITE.* W.W. Brandt & W. Rudloff (Department of Chemistry, Illinois Institute of Technology, Chicago 16, Illinois, U.S.A.). The rates of sorption of several gases on chabazite, a natural zeolite, have been measured, using a constant volume system and automatic recording of pressure changes. The relevant solutions of the diffusion equation are computed and tabulated, and are used to analyze the sorption processes from essentially zero to infinite time.
The sorption of carbon dioxide appears to be controlled by a slow adsorption step, but the data obtained for methane and argon can best be explained by assuming the natural crystals either to contain grain boundaries of high permeability, or to be traversed by relatively thin shells of compact and probably amorphous material of low permeability. The possible effects of the grain shape irregularity and size distribution have been explored. (Received 7 Ms~ 1963; in revised form 13 August 1963)
13. SEMICONDUCTION AND CATION VALENCIES IN MANGANESE FERRITES. F.K. Lotgering (Fhilips Research Laboratories, N.V. Philips' Gloeilampenfabrieken, Eindhoven, The Netherlands). *Abstracted in part from work done by W. Rudloff in partial fulfi11-~ut of the research requirement for the Ph.D. degree in the Department of Chemistry at Illinois Institute of Technology.