The dielectric properties of a number of synthetic aluminosilicate minerals have been determined by means of a.c. measurements. A Hartshorn—Ward dielectric test set was used for the measurements in the range 74kc/s to 2mc/s and at lower frequencies a bridge with inductively coupled ratio arms was employed, The temperatures at which the measurements were made were within the range —196 to 35000. The lithium minerals studied have reasonably low loss values which increased with decreasing frequency, The loss/log,(frequency) plots for 4,—eucryptite give maxima within the measuring range, which are ascribed to relaxation of trapped electrons. The measurements on nepheline hydrate and its ignition product show that these two materials have very similar values for the dielectric loss and for the temperature coefficient of the loss, This suggests that the water in nepheline hydrate is strongly bound in the crystal and does not make a large contribution to the loss of this material at the temperatures used in the measurements, The barium feldspar, celsian, and the synthetic strontium polymorph of feldspar both exhibit conduction of a d.c. nature at the higher temperatures used. The conduction in the potassium feldspar, sanidine, has a large contribution from d.c. conduction circa 25000 and indications are that it will be mainly of that type at somewhat higher temperatures. The anhydrous sodium chabazite has loss peaks within the measuring range. These are attributed to cation jumps. A slightly hydrated sample of sodium chabazite has much lower loss values, with no maxima, in the region where the peaks occur for the anhydrous sample.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:602172 |
| Date | January 1962 |
| Creators | Coen, Patrick Joseph |
| Publisher | Imperial College London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/10044/1/13677 |
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