The thermal conductivity of pure and iron-doped quartz and lithium niobate single crystals at very low temperatures
The thermal conductivity of pure and iron-doped quartz and lithium niobate single crystals at very low temperatures
The thermal conductivity of pure and iron-doped quartz crystals has been measured between 0.3K and 6K. The conductivity of the iron-doped quartzshows an enormous decrease compared with that of the pure specimen, exhibiting a pronounced 'dip' between 0.5K and 5K. This large reduction in conductivity is attributed to the presence of colloidal iron particles in the doped sample. The scattering cross section of the colloids as a function of frequency is evaluated numerically using the method of partial waves. The thermal conductivity results are analysed using the phenomenological theory proposed by Callaway and a value of 309 is deduced for the average colloid radius. This value differs from previous estimates obtained from the analysis of the conductivity results at higher temperatures. The thermal conductivity of a lithium niobate crystal has been measured between 0.3K and 5K. The results indicate the presence of a large number of point scatterers. These point defects are believed to be iron ions as reported by other authors.
University of Southampton
1983
Bahrevar, Mohammad Ali
(1983)
The thermal conductivity of pure and iron-doped quartz and lithium niobate single crystals at very low temperatures.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The thermal conductivity of pure and iron-doped quartz crystals has been measured between 0.3K and 6K. The conductivity of the iron-doped quartzshows an enormous decrease compared with that of the pure specimen, exhibiting a pronounced 'dip' between 0.5K and 5K. This large reduction in conductivity is attributed to the presence of colloidal iron particles in the doped sample. The scattering cross section of the colloids as a function of frequency is evaluated numerically using the method of partial waves. The thermal conductivity results are analysed using the phenomenological theory proposed by Callaway and a value of 309 is deduced for the average colloid radius. This value differs from previous estimates obtained from the analysis of the conductivity results at higher temperatures. The thermal conductivity of a lithium niobate crystal has been measured between 0.3K and 5K. The results indicate the presence of a large number of point scatterers. These point defects are believed to be iron ions as reported by other authors.
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Published date: 1983
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Local EPrints ID: 460176
URI: http://eprints.soton.ac.uk/id/eprint/460176
PURE UUID: fb24a000-ec69-4496-b0ab-936a10daad1e
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Date deposited: 04 Jul 2022 18:06
Last modified: 04 Jul 2022 18:06
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Author:
Mohammad Ali Bahrevar
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