Atom positions from hyperfine data for germanium centers in α‐quartz

Mombourquette, Michael J.; McEachern, R. J.; Weil, John A.

doi:10.1002/mrc.1260331313

Cited by 7 publications

(8 citation statements)

References 24 publications

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“…In practice, Eq. [2] is showing the distribution of about 150 crystallites over the 2D approximated by the sum a, b plane as well as over the 3D surface of the unit sphere. It is evident that random selection leads to a rather nonuniform (8), Conroy (9), and Wolfsberg and co-workers (10) (henceforth referred to as ZCW), the attracted considerable interest as a very efficient powder-aver- aging method (4).…”

Section: Introductionmentioning

confidence: 99%

REPULSION, A Novel Approach to Efficient Powder Averaging in Solid-State NMR

Bak

Nielsen

1997

Journal of Magnetic Resonance

356

225

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Section: Introductionmentioning

confidence: 99%

REPULSION, A Novel Approach to Efficient Powder Averaging in Solid-State NMR

Bak

Nielsen

1997

Journal of Magnetic Resonance

356

225

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“…2. 6) It is known that [Ge(C)e À /Li þ ] and [Ge(C)e À /Na þ ] exhibit equivalent g-factors at H k c-axis, but [Ge(C)e À / Na þ ] is unstable at room temperature; 7) thus, the obtained ESR signal is identified as [Ge(C)e À /Li þ ]. The sample was irradiated using UV light sequentially as shown in Table II.…”

mentioning

confidence: 98%

Optically Induced Conversion of Ge Centers in Quartz

Katsura¹,

Yamanaka²

2006

Jpn. J. Appl. Phys.

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An electron spin resonance (ESR) study of natural single crystalline quartz was performed to clarify the effect of ultraviolet rays (UV) exposure on electron traps at germanium impurities. ESR spectra of artificially -irradiated single crystalline samples from two different natural sites mainly showed a common Ge center, [Ge(C)e À /Li þ ], which is an electron trapped center at a Si-substituting Ge ion with a charge compensator of Li þ . UV light exposure using a low-pressure mercury lamp converted [Ge(C)e À /Li þ ] into a different paramagnetic center. The observed ESR parameters of this center did not coincide with those of other known centers. This signal gradually decayed at room temperature and simultaneously produced a third center, Ge E 2 0 , which is a germanium dangling bond neighboring an oxygen vacancy with the form Si-H Ge. The experimental results indicated a two-step conversion of Ge centers, which was caused by UV exposure and aging. The total spin concentration was kept constant throughout the experiments.

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“…All cylinders were first thermally bleached in air at 673 K for 6 h. One such cylinder was mounted on a crystal holder and irradiated at 77 K and then transferred cold to the temperature-controlled EPR cavity system for measurements at 15 K [6]. This plate was cut to yield three cylinders, each of which was oriented to have its (right circular) cylinder axis parallel to one (≡ a 1 ) of the three crystallographic two-fold piezoelectric axes a i (i = 1, 2, 3).…”

Section: Samples and Epr Experimentsmentioning

confidence: 99%

“…The occurrence of Ge-Li centres has been known since the 1950s, and has been the subject of considerable investigation [3][4][5][6]. The formation of the Ge-Li centres is now generally well understood.…”

Section: Introductionmentioning

confidence: 99%

“…When germanium-containing crystals are xirradiated at sufficiently low temperature (77 K) and examined without warming, charge-uncompensated germanium centres are observed, along with the compensated aluminum hole centres [AlO 4 /M] + (where M = Li or Na) [7]. The most prominent of these are the well-known centres A Li , C Li (≡ [GeO 4 /Li] 0 A,C ), and A Na (≡ ([GeO 4 /Na] 0 A ) [3][4][5][6]. On warming above 150 K, migration of the cationic compensators from the aluminum hole centres occurs and the uncompensated germanium centres are converted to compensated centres.…”

Section: Introductionmentioning

confidence: 99%

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Paramagnetic Ge–Li centres in alpha quartz revisited: The D_Li([GeO₄/Li]⁰_D) centre

Claridge¹,

Kryliouk²,

Weil³

et al. 2008

Can. J. Phys.

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A previously unreported stable paramagnetic defect centre in single-crystal alpha-quartz has been studied by quantitative X-band electron paramagnetic resonance spectroscopy at 15, 100, and 296 K, and is shown to contain a Ge 3+ ion, presumably located substitutional for Si 4+ , with a nearby interstitial Li + ion. The centre, called D Li herein, grows in slowly (months) after room-temperature x-irradiation and storage. Hyperfine structure arising from 73 Ge, 7 Li, and 29 Si has been observed. The spin-Hamiltonian parameter matrices g, A( 7 Li), A( 73 Ge), and P( 73 Ge) are reported, also for centre C Li . A thermal dynamic process, probably involving Li + hopping, begins to be appreciable above 100 K. Discussion of D Li , its apparent growth from another paramagnetic centre (not yet fully characterized), and comparison with other similar defects is included.Résumé : Nous étudions un nouveau centre de défaut paramagnétique stable dans le cristal simple du quartz alpha par spectroscopie EPR à bande X, à 15, 100 et 296 K et nous montrons qu'il contient un ion Ge 3+ , vraisemblablement substitutionnel sur le site du Si 4+ , avec un ion interstitiel proche Li + . Le centre , appelé ici D Li , croît lentement (mois) après irradiation X à température de la pièce et gardé au repos. Nous avons observé les structures hyperfines provenant de 73 Ge, 7 Li et 29 Si. Nous présentons les matrices g de paramètres du Hamiltonien de spin, A( 7 Li), A( 73 Ge) et P( 73 Ge), ainsi que pour un centre C Li . Un mécanisme dynamique thermique, impliquant vraisemblablement des sauts atomiques Li + , devient appréciable au delà de 100 K. Dans une discussion sur D Li nous incluons sa croissance apparente à partir d'un autre centre paramagnétique (pas encore caractérisé) et des comparaisons avec d'autres défauts similaires.[Traduit par la Rédaction]

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Atom positions from hyperfine data for germanium centers in α‐quartz

Cited by 7 publications

References 24 publications

REPULSION, A Novel Approach to Efficient Powder Averaging in Solid-State NMR

REPULSION, A Novel Approach to Efficient Powder Averaging in Solid-State NMR

Optically Induced Conversion of Ge Centers in Quartz

Paramagnetic Ge–Li centres in alpha quartz revisited: The D_Li([GeO₄/Li]⁰_D) centre

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Atom positions from hyperfine data for germanium centers in α‐quartz

Cited by 7 publications

References 24 publications

REPULSION, A Novel Approach to Efficient Powder Averaging in Solid-State NMR

REPULSION, A Novel Approach to Efficient Powder Averaging in Solid-State NMR

Optically Induced Conversion of Ge Centers in Quartz

Paramagnetic Ge–Li centres in alpha quartz revisited: The DLi([GeO4/Li]0D) centre

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Product

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Paramagnetic Ge–Li centres in alpha quartz revisited: The D_Li([GeO₄/Li]⁰_D) centre