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Lazarus, David Allen, Paul Clement 2011-07-01T17:55:09Z 2011-07-01T17:55:09Z 10000-01-01 1977 The effect of pressure on the ionic conductivity of RbAg4I5 and AgI has been measured, using single crystals and polycrystalline samples, up to pressures of 6 kbar. The activation volumes for motion in cr-RbAg4I5 and B-RbAgI5, respectively, are -0.4 ±.2 cm3/mole and -0.2 ±.l cm3/mole. In 4a-AgI, the motion volume increases from 0.56 ±.l cm3 /mole at 435 K to 0.8 ±.l cm3/mole at 623 K. These values are unusually small in relation to the activation energies and are not consistent with the strain energy model or a domain diffusion mechanism. The negative activation volume for super-ionic RbAgIand the small size of the activation volume for cr-AgI may be 4S the result of pressure increasing the interaction enthalpy between the diffusing ions. The logarithms of the ionic conductivities of cr-and B-RbAgIin4S crease linearly at first and then decrease quadratically with pressure. This is related to the large quadratic pressure dependence of the second-order transition temperature, 6T (K) = 0.14lP (kbar) + 0.111p2 (kbar2). c The variation of the 122 K transition temperature with pressure is 6T(K) = S.6SP (kbar) -0.S3P2 (kbar2), implying a molar volume change of c VB -Vy = 0.37 ±.Ol cm3 /mole and a change in compressibility KB -Ky = 0.033 ±.OOI x 10-11 cm2/dyne, across the transition. The ionic conductivity of y-RbAg Iinitially decreases with an 4S activation volume of 9 ±l cm3/mole, and then levels off with increasing pressure. This may be the result of an extrinsic-like region or of grain-boundary conduction. The negative activation volume for conduction along the c-axis in B-AgI has been confirmed. Both low-temperature phases have large formation volumes consistent with the theory of Rice et al. of transitions to the superionic phase. Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-07-01T17:55:09Z No. of bitstreams: 1 1977_allen.pdf: 2559598 bytes, checksum: a371179b1b73dbdcdc04abc1f747b578 (MD5) Made available in DSpace on 2011-07-01T17:55:09Z (GMT). No. of bitstreams: 1 1977_allen.pdf: 2559598 bytes, checksum: a371179b1b73dbdcdc04abc1f747b578 (MD5) Previous issue date: 1977 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Mead (cmead2@illinois.edu) on 2011-07-01T17:55:09Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:32:34-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis Thesis U of I Only 252664 http://hdl.handle.net/2142/25625 en 1977 Paul Clement Allen ionic conductivity rubidium silver iodide silver iodide single crystals polycrystalline Effect of pressure on ionic conductivity in rubidium silver iodide and silver iodide Dissertation / Thesis text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.