Electronic energy-band structure of α quartz

Calabrese, E.; Fowler, W. Beall

doi:10.1103/physrevb.18.2888

Cited by 103 publications

(29 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There the effective charges of the silicon atom Si, and the oxygen atom 0, are presented, which in all considered cases have the greatest number of next neighbours. It can be seen that already beginning with the cluster consisting of three structural units, the results are close t o each other and in good agreement with those obtained in band structure calculations [50,51] and T a b l e 2 Dependence of the effective charges of central ions (see Fig. 6 _ _~ *) Symmetric cluster composed of five SiO, molecules (see Fig.…”

Section: Resultssupporting

confidence: 87%

Application of molecular models to electronic structure calculations of defects in oxide crystals

Geisser

Shluger

1986

Physica Status Solidi (b)

View full text Add to dashboard Cite

Ab initio and INDO methods are applied to investigate the interaction between several SiO, molecules and for electronic structure calculations of idealized p-cristobalite within the framework of the cluster model. Stoichiornetric fragments are chosen for simulating perfect and imperfect crystal structures of SiO, by means of combinations of interacting structural units 0-Si-0. The boundary conditions for such clusters are imposed in the form of the electrostatic fields in the rest of the crystal. The results of the electronic structure calculations are only slightly dependent on size and shape of the chosen clusters and agree quite well with experimental data. IntroductionA t present more and more theoretical electronic structure calculations of perfect and imperfect silicon dioxide appear [I t o 71. These calculations mostly have been carried out within the framework of the so-called molecular models of perfect and defectcontaining crystals, i.e. cluster models and cyclic models. The latter are based on the

show abstract

Section: Resultssupporting

confidence: 87%

Application of molecular models to electronic structure calculations of defects in oxide crystals

Geisser

Shluger

1986

Physica Status Solidi (b)

View full text Add to dashboard Cite

show abstract

“…There are two main differences between SiO 2 and Li 2 O. First, the valence band of SiO 2 is derived mainly from oxygen 2p state with some contributions of silicon 3s, 3p and 3d states, and the conduction band consists of considerable admixtures of O 2s and 2p and Si 3s and 3p states [28]. Consequently, the excitonic excitation changes the chemical bonding of the oxygen with the neighboring silicon ions.…”

Section: Discussionmentioning

confidence: 98%

Intrinsic Luminescence from Li2O Crystals Excited in the Exciton-Band Region

Itoh

Murakami

Ishii

1999

phys. stat. sol. (b)

View full text Add to dashboard Cite

Photoluminescence of lithium oxide (Li2O) has been studied under the excitation with UV light in the fundamental absorption region at low temperatures. Two bands appear at 3.70 and 4.75 eV. The 3.70 and 4.75 eV bands are stimulated on the low‐ and high‐energy sides of the exciton reflection band peaking at 7.02 eV, respectively. An interesting fact is that there appears no luminescence under the above‐gap excitation. The 4.75 eV band is ascribed to radiative decay of self‐trapped excitons, and the 3.70 eV band is related to unavoidably existing defects or impurities. Both a broadening of the line width and a quenching of the intensity of the 4.75 eV band are also investigated in the temperature range 9 to 300 K. The present result is discussed in comparison with the theoretical model of the self‐trapped exciton in this material.

show abstract

“…in K 2 SO 4 ) [34]. The first band structure calculation did not predict the energy gap between the valence subbands of a-quartz [38]. However, the value of E vg % 1.5 eV was obtained in more advanced calculations (see, e.g.…”

Section: Hot E-h Recombination and Defect Creation In Oxidesmentioning

confidence: 99%

Defect creation caused by the decay of cation excitons and hot electron–hole recombination in wide-gap dielectrics

Lushchik

Kirm

et al. 2006

Nuclear Instruments and Methods in Physics Research Section B:

View full text Add to dashboard Cite

Insufficient radiation resistance of construction materials is the Achilles heel for thermonuclear energetics. In wide-gap dielectrics, Frenkel defects are created not only because of the knock-out (impact) mechanism but also because of the decay of the electronic excitations formed during the irradiation (i.e. due to nonimpact mechanisms). The processes of the defect creation at the irradiation of highly pure LiF single crystals at 6-8 K by 1-30-keV electrons, X-rays, or synchrotron radiation of 12-70 eV have been investigated. The annealing processes of these defects in a temperature range up to 200 K have been studied as well. In LiF, creation has been revealed for the following: (1) F-H pairs caused by the decay of anion excitons or by the recombination of electrons and holes, (2) F 0 -H-V K and F-I-V K defect groups at the decay of cation excitons (62 eV), or (3) 20-keV electron irradiation. The mechanism of defect creation at the recombination of hot holes and hot electrons has been discussed for a-SiO 2 crystals with an energy gap between the subbands of a valence band. One of the possible ways to suppress this mechanism (''luminescent defence'') is doping a material by luminescent impurities able to capture a part of the energy of hot carriers before their relaxation and recombination (e.g. in MgO:Cr).

show abstract

Electronic energy-band structure of α quartz

Cited by 103 publications

References 33 publications

Application of molecular models to electronic structure calculations of defects in oxide crystals

Application of molecular models to electronic structure calculations of defects in oxide crystals

Intrinsic Luminescence from Li2O Crystals Excited in the Exciton-Band Region

Defect creation caused by the decay of cation excitons and hot electron–hole recombination in wide-gap dielectrics

Contact Info

Product

Resources

About