Complex impedance spectroscopy of alkali impurities in as-grown, irradiated and annealed quartz

Abstract

Articles you may be interested inDielectric relaxation and alternating current conductivity of lanthanum, gadolinium, and erbium-polyvinyl alcohol doped films J. Appl. Phys. 112, 034102 (2012); 10.1063/1.4739752An analysis of Mn-Zn ferrite microstructure by impedance spectroscopy, scanning transmission electron microscopy and energy dispersion spectrometry characterizations Variable temperature measurements of the complex dielectric permittivity of lossy AlN-SiC composites from 26. 5-40 GHzThis work compares the dielectric relaxation properties of different crystalline quartz materials, according to their source ͑natural or synthetics͒. It is shown that these relaxation properties are due to a hopping process of alkaline ͑Li + , Na + , and K + ͒ impurities located near ͓Al-O 4 ͔ 5− tetrahedra. A detailed analysis, in terms of the distribution function of the dielectric loss peak, allowed us to perfectly distinguish the different types of as-grown quartz. We show that ͑i͒ the natural quartz has less stable M + charge carriers than the synthetic materials and that ͑ii͒ the homogeneity of the M + trapping sites, created by the ͓Al-O 4 ͔ 5− tetrahedra, strongly depends on the crystal growth conditions. These features were then studied using quartz samples with different treatment conditions: as-grown, irradiated, or annealed at high temperature. We propose that the irradiation greatly facilitates the M + relaxation, by creating additional low energy M + hosting sites, whose number depends on the source of the quartz crystals. We also show that for 100 krad irradiation, the saturation state of the defects is already reached for all the materials under consideration. Finally, we propose that the irradiation followed by annealing at 450°C improves the M + stability and homogeneity in quartz materials, compared with the as-grown materials, this trend being much more relevant for the natural than for the synthetic quartz.

Characterization of unswept and swept quartz crystals for space applications

“…This observation demonstrates that alkali ions are less trapped in the irradiated samples and relax more easily. [39][40][41][42] It is consistent with the fact that upon irradiation at temperatures above 200 K, 33,43 alkali ions are released from their initial host site and replaced by electron holes to form the Al-h + defects. The alkali interaction with the oxygen atom of the aluminum tetrahedron thus decreases.…”

“…As reported in Table I, the relaxation of charge carriers strongly depends on the irradiation dose in the unswept quartz in contrast to what was already reported for doses greater than 100 Gy. 42 The following tendency is in quite good agreement with the creation of ͓Al Si O 4 − / Li + ͔ + defects upon irradiation, which was demonstrated by Halliburton et al, 44 This suggests that the detrapping energy calculated for the irradiated quartz is inversely proportional to the number of lithium-related defects induced by irradiation. The appearance of two dielectric loss peaks in the unswept quartz exposed to 10 Gy may be due to the relaxation of two groups of charge carriers related to Li + and Na + relaxations, respectively.…”