Abstract of Thesis (Ph. D.)--University of Michigan, 1933. / Caption title. "Reprinted from Transactions of the American institute of chemical engineers, vol. XXIX, 1933." "Literature cited": p. 159.

Thesis (Sc. D.)--Catholic University of America, 1934. / At head of title: The Catholic university of America. Vita. Bibliography: p. 70-80.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 110-116). Available also in a digital version from Dissertation Abstracts.

Inaug.-diss.--Jena. / Vita.

No description available.

No description available.

Thesis (Ph.D.)--University of Iowa, 2009. / Includes separate files for thesis supplements. Thesis supervisor: David E. Stewart. Includes bibliographical references (leaves 107-109).

Attrition occurs during the transport and storage of particles and leads to loss of material through dust formation and to environmental pollution. Standard tests are all specifically designed to cater for particular needs and are often indicators of relative hardness than of attrition rates. Since little progress has been made into understanding the mechanisms of attrition, the purpose here is to study one of the basic processes that determines the rate of grinding. The aim is thus to establish a fundamental framework within which past work and future developments can be assessed. An annular attrition cell was designed, constructed and commissioned to permit one of the mechanisms of attrition, namely that in failure zones of deforming solids, to be considered in isolation. Sample weights of 100 gm were more than sufficient and the results were found to be reproducible, systematic and generally independent of sample size. Several close-sized material in the size range 250-2000 µm of various shapes were studied including different grades of sodium chloride, sodium carbonate and molecular sieve beads. The mode of attrition, bodily fracture or surface grinding, was easily verified by microscopic examination of attrited product. Results followed Gwyn's empirical law W = K_p t^m where W denotes the weight fraction attrited, t time and K_p , m are characterising parameters. The reliable data permitted the development of simple kinetic models. One supposes first order loss of coarse material, another that attrition rate is dependent on radius reduction. It may be argued that the former applies to a fracturing mechanism, the latter to a surface grinding process. The first order approach has to be modified to allow for the initial high rate of attrition; the second model may be reduced to the Gwyn form. The attrition cell is useful in characterising materials; it should, in future, permit assessment of equipment performance.

In this thesis, we present results of studies of the electronic band structures and related electronic properties of some layered transition metal chalcogenides and their intercalation complexes. The materials investigated include group VIIc transition metal dichalcogenides, and 2H-TaS<SUB>2</SUB> and its lithium-, lead-, and tin-intercalated complexes, as well as dihafnium sulphide and selenide. Both experimental measurements and theoretical elect'onic band structure calculations have been carried out. The types of measurements conducted consist of reflectivity measurements in the energy range from 0.5 eV to 4.5 eV using the home-made reflectivity spectrometer, and electron energy loss measurements in the energy range up to 100 eV using the scanning transmission electron microscope as well as some characterization experiments (structural, chemical composition and thermal properties). The experimental investigations were restricted to the layered group VIIc metal dichalcogenides. All the electronic band structures are calculated using the linearized muffin-tin orbital (LMTO) method, and are reported for the first time except PdTe<SUB>2</SUB> and 2H-TaS<SUB>2</SUB>. The obtained electronic band structures for the Ni-group metal dichalcogenides, and the semiconductor-metal shift in progression from PtS<SUB>2</SUB> through PtSe<SUB>2</SUB> to PtTe<SUB>2</SUB> are discussed in terms of the binding energies of the atomic valence orbitals of the constituent atoms, the local coordination of the metal atoms and the symmetry of the crystals as well as the charge transfer effects. A superlattice structural phase transition is proposed for PtSe<SUB>2</SUB>, which may possibly explain the anomaly observed in the previous transport measurement. The previous photoemission spectra from NiTe<SUB>2</SUB>, PdTe<SUB>2</SUB> and PtTe<SUB>2</SUB>, and dHvA measurement on PdTe<SUB>2</SUB> are compared with their band structures in details, and a good agreement is found. Other available experimental data including the previous transport, optical and magnetic susceptibility measurements as well as the reflectivity and electron energy loss spectra measured in this work are also discussed in terms of these electronic structures. The band structure calculations for dihafnium chalcogenides predict that these materials are metals. They also suggest that there is a strong bonding between Hf atoms in the adjacent layers, thus giving rise to the rigidity in the c-direction which may preclude the intercalation of these materials. The results for 2H-TaS<SUB>2</SUB> and its intercalation complexes show that the rigid band model is essentially correct for 2H-LiTaS<SUB>2</SUB> but is an oversimplication for the post-transition metal intercalation compounds. Changes in the electronic structure upon intercalation are discussed in terms of the intercalant-host charge transfer and the hybridisation between the host states and the intercalation valence orbitals. Electrical conduction in 2H-PbTaS<SUB>2</SUB> and SnTaS<SUB>2</SUB> is found to be largely due to the p-valence electrons from the intercalant Pb (Sn) layers, resulting in the considerable increase in the superconducting transition temperature following intercalation. The results are also compared with the observed optical and transport properties and a broad agreement is found. The band structures and the electronic properties of other layered transition metal dichalcogenides and their intercalation complexes, as well as the band structure calculation techniques for the layered compounds are also reviewed in this thesis.

No description available.