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1

Overtone Modes in an At-Cut Quartz Trapped-Energy Resonator with Elliptical Electrodes

100%

Li L., Wang Z.

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2017

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vol. 131

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issue 2

294-296

EN

We analyze thickness-shear vibrations of an at-cut quartz plate with elliptical electrodes. The electrodes are essentially optimal in the sense of Mindlin in that they approximately satisfy the criterion for the Bechmann number in every direction. The scalar differential equation derived by Tiersten and Smythe is used which allows us to obtain the overtone modes in addition to the fundamental modes.

2

Luminescence of silicon Dioxide - silica glass, α-quartz and stishovite

100%

Trukhin A., Smits K., Chikvaidze G., Dyuzheva T., Lityagina L.

Open Physics

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2011

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vol. 9

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issue 4

1106-1113

EN

This paper compares the luminescence of different modifications of silicon dioxide - silica glass, α-quartz crystal and dense octahedron structured stishovite crystal. Under x-ray irradiation of pure silica glass and pure α-quartz crystal, only the luminescence of self-trapped exciton (STE) is detected, excitable only in the range of intrinsic absorption. No STE luminescence was detected in stishovite since, even though its luminescence is excitable below the optical gap, it could not be ascribed to a self-trapped exciton. Under ArF laser excitation of pure α-quartz crystal, luminescence of a self-trapped exciton was detected under two-photon excitation. In silica glass and stishovite mono crystal, we spectrally detected mutually similar luminescences under single-photon excitation of ArF laser. In silica glass, the luminescence of an oxygen deficient center is presented by the so-called twofold coordinated silicon center (L.N. Skuja et al., Solid State Commun. 50, 1069 (1984)). This center is modified with an unknown surrounding or localized states of silica glass (A.N. Trukhin et al., J. Non-Cryst. Solids 248, 40 (1999)). In stishovite, that same luminescence was ascribed to some defect existing after crystal growth. For α-quartz crystal, similar to silica and stishovite, luminescence could be obtained only by irradiation with a lattice damaging source such as a dense electron beam at a temperature below 80 K, as well as by neutron or -irradiation at 290 K. In spite of a similarity in the luminescence of these three materials (silica glass, stishovite mono crystal and irradiated α-quartz crystal), there are differences that can be explained by the specific characteristics of these materials. In particular, the nature of luminescence excited in the transparency range of stishovite is ascribed to a defect existing in the crystal after-growth. A similarity between stishovite luminescence and that of oxygen-deficient silica glass and radiation induced luminescence of α-quartz crystal presumes a similar nature of the centers in those materials.

3

Pytania o kwarc deformacyjny i szokowy

86%

Kosina R.

Acta Societatis Metheoriticae Polonorum

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2014

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vol. 5

52-71

EN

Quartz, known as a common mineral on our planet, is used as a good marker of microstructural deformation created by tectonic activity or meteorite impact. Planar fractures (PFs) and planar deformation features (PDFs) are not randomly oriented in an impacted quartz crystal, but are distinctly connected to crystallographic planes. In a tectonically deformed quartz PDFs are mostly parallel to the plane (0001), but can also be bent. Recrystallization reduces the level of dislocations in such a quartz. However, the difference between both types of quartz is quantitative and not qualitative. One might expect that the impact could reactivate or induce new tectonic metamorphism and/or volcanic activity. In addition, P-T parameters decrease continuously from the impact centre toward outside. Then, intermediate forms of quartz deformation ought to be distinguished. The paper also presents the point of view that the location and identification of deformed and shocked quartz, as well as some allochtonic Scandinavian impactites, transported into the Central Europe during the last glaciation, is highly probable in areas of enhanced tectonic activity in Lower Silesia, Poland. Identification of local rocks with pseudotachylite properties and recognition of their nature, deformed versus shocked, could also be helpful here.

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1 Smits K.

1 Trukhin A.

1 Wang Z.

Overtone Modes in an At-Cut Quartz Trapped-Energy Resonator with Elliptical Electrodes

Luminescence of silicon Dioxide - silica glass, α-quartz and stishovite

Pytania o kwarc deformacyjny i szokowy