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Koehler, James S. Kliewer, Kenneth Lee 2011-05-18T20:28:24Z 2011-05-18T20:28:24Z 10000-01-01 1964 The equilibrium defect distribution is calculated for a pure ionic crystal of the type M+X=. It is shown that the normally assumed state of bulk electrical neutrality is a consequence of the presence of potential fields beneath the surfaces and around edge dislocations. These potential fields~ resulting from imperfection space charge~ modi,fy the innate free formation energies of the defects in a manJ:!ier such that bulk electrical neutrality exists at sufficiently high temperatures. At low temperatures it is shown that bulk electrical neutrality does not exist and effects due to the dislocation denSity are discussed. Calculations are given for crystals in which Schottky disorder predominates as well as for crystals in which Frenkel disorder predominates. Calculations of the equilibrium defect distribution for crystals containing divalent impurities are also given. Again it is shown, that, because of potential fields beneath the surfaces and around edge dislocations~ bulk electrical neutrality exists at sufficiently high temperatures. The influence of association of oppositely charged defects is described using a short range interaction. In addition the manner in which explicit account can be taken of the formally included long range interaction is outlined. The theory is applied in detail to NaCl. It is shown that edge dislocations» both in pure and doped crystals» develop,·a charge which is compensated electrically by a surrounding space charge. The charge on the dislocation is discussed with reference to recent work dealing with charged dislocations. The effect of the charge distribution on and around the dislocations on the mechanical properties of ionic crystals is discussed. Explanations for the Joffe effect and the brittleness of ionic crystals are proposed. The presence of the potential field at a surface is discussed with reference to the electron affinity of ionic crystals. Finally» an experiment is proposed whereby the potential difference across the surface potential field can be measured directly. Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-05-18T20:28:24Z No. of bitstreams: 1 1964_kliewer.pdf: 5564772 bytes, checksum: bd0936152b798beebdd5d1172a7a534a (MD5) Made available in DSpace on 2011-05-18T20:28:24Z (GMT). No. of bitstreams: 1 1964_kliewer.pdf: 5564772 bytes, checksum: bd0936152b798beebdd5d1172a7a534a (MD5) Previous issue date: 1964 Restriction data tranferred 2014-07-01T11:15:42-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Mead (cmead2@illinois.edu) on 2011-05-18T20:28:24Z Item is restricted indefinitely. Thesis U of I Only 6152248 http://hdl.handle.net/2142/23952 en 1964 Kenneth Lee Kliewer equilibrium defect distribution ionic crystal space charge divalent impurities Space charge resulting from imperfections and effects thereof in ionic crystals Dissertation / Thesis text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.