A study of lattice defects in solids belonging to Al2O3−B2O3 and Al2O3−SiO2 systems by thermoluminescence experiments

Brovetto, P.; Delunas, A.; Maxia, V.; Salis, M.; Spano, G.; Mazza, Daniele; Vallino, M.; Delmastro, A.

doi:10.1007/bf02457126

Cited by 3 publications

(5 citation statements)

References 4 publications

(9 reference statements)

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“…This feature is in good agreement with data of TL experiments, which are characterized by emission of light distributed on broad temperature ranges [1][2][3]. This special behaviour of aluminosilicates is a consequence of the high density of crystal defects originating in these materials.…”

Section: -Discussion and Conclusionsupporting

confidence: 90%

“…By heating the crystals, electrons or holes thermally released from traps give rise to radiative recombinations. In fact, TL experiments performed on different aluminosilicates [1,2], also including lacunar compounds [3], showed a peculiar disorder in the electron trap depths which, as will be proved, can be explained by considering the aforesaid electrostatic interactions.…”

Section: -Introductionmentioning

confidence: 71%

“…(3.6) leads to aaf = 2.5/~. A different, more appropriate estimate takes into account that the TL emission of aluminosilicates occurs at rather high temperatures which exceed some 400 K [1][2][3]. This means that the trap depths, and thus the values of 7171, are on the order of 1 eV.…”

Section: Ddmentioning

confidence: 99%

“…A final point which is worth mentioning is the fact that TL emissions of aluminosilicates, as seen along the wavelength axis, consist of fairly well-resolved peaks [1][2][3]. This means that recombination levels, unlike electron trapping levels, are exempt from disorder.…”

Section: ~mentioning

confidence: 99%

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A Debye model for point defects in aluminosilicate crystals

et al. 1993

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(ricevuto il 31 Agosto 1993; approvato il 24 Settembre 1993)Summary. --In aluminosilicate lattices, exchanges between silicon and aluminum ions are expected to originate charged point defects of opposite signs. Thermodynamic arguments, based on a model analogous to the Debye electrolyte model, allow evaluation of the equilibrium density of defects as a function of temperature. The electric field of point defects is found to be screened by charge distribution even at distances small enough to affect the ground-state energy of electrons trapped by the defect positive charges. Calculations show that large fluctuations of trapped electron energy are expected. These results agree with data from thermoluminescence experiments on different aluminosilicates, which showed broad distributions of electron traps. PACS 61.70.Ey -Defects in crystals: other point defects. PACS 78.60.Kn -Thermoluminescence.

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Section: -Discussion and Conclusionsupporting

confidence: 90%

Section: -Introductionmentioning

confidence: 71%

Section: Ddmentioning

confidence: 99%

Section: ~mentioning

confidence: 99%

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A Debye model for point defects in aluminosilicate crystals

et al. 1993

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“…The last one is particularly high. It in fact exceeds that of materials containing AIOa and SiOt tetrahedra previously investigated [4] by a factor as large as ten.…”

Section: Investigation Of Cordierite Lattice Defects By Thermoluminesmentioning

confidence: 65%

Investigation of cordierite lattice defects by thermoluminescence experiments

Brovetto¹,

Maxia²,

Salis³

et al. 1992

Nouv Cim D

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Point defects in ionic crystals originate localized charges which, when crystals are excited by ionizing radiations at low temperature, trap opposite-sign carriers. The thermoluminescent (TL) emission which ensues when carriers are released from traps at high temperature yields information on this kind of defects.By TL experiments we investigated samples of ~-and a-cordierite, which is a magnesium alumino-silicate characterized by the presence of ring-shaped anionic radicals similar to the Si6 01s ring radicals of beryl structure. The easy exchange of Si and A1 ions in oxygen tetrahedra, which is peculiar to these compounds, is expected to originate point charges detectable by recording the TL emission. -Experiments.Samples having composition Mg2A14 Si 5 018 were prepared by a solgel route. An aqueous solution of aluminum and magnesium nitrates in proper amounts was added to the stoichiometric quantity of tetraethylorthosilicate (TEOS), adjusting the resultant pH to 1.5 with HNOs. On raising temperature to 80~ while stirring, TEOS slowly hydrolizes and dissolves into the solution of the two nitrates. Thus a clear solution is obtained, which is gelled by rapid addition of excess aqueous ammonia solution. The basic (pH = 10) gel obtained is then gradually heated up to 400 ~ thus 657

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