Ablation of solid hydrogen in a plasma

Jørgensen, L. W.; Sillesen, Alfred

doi:10.1088/0022-3727/12/12/016

Cited by 27 publications

(37 citation statements)

References 18 publications

(17 reference statements)

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“…Another study which is also relevant in this respect is that of Jorgenson. 22 He measured the interatomic distances as a function of pressure in the ␣-quartz forms of SiO 2 and GeO 2 . As said, higher crystalline and amorphous counterparts have the same build-ing blocks, the tetrahedra.…”

Section: Quantitative Discussionmentioning

confidence: 99%

Tunneling states in vitreousGeO2s

Laermans¹,

Keppens²,

Weeks³

1997

Phys. Rev. B

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Ultrasonic measurements of the attenuation and the velocity variation have been carried out in amorphous GeO 2 at low temperature ͑0.3-10 K͒ and high frequencies ͑80-210 MHz͒. From numerical fits to the tunneling model, the typical parameters of the tunneling states ͑TS͒ were determined and compared to those found for vitreous SiO 2 . The study reveals that in a-GeO 2 , which is considered as a close structural analog to a-SiO 2 , although the density of states is found to be very similar in both materials, the coupling between the TS and the phonons is significantly smaller. In the model of coupled tetrahedra as the origin of the TS, this difference can be understood in view of the fact that numerical calculations about the vibrational characteristics of network amorphous solids indicate that the tetrahedra are more decoupled in vitreous GeO 2 than in vitreous silica.

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Section: Quantitative Discussionmentioning

confidence: 99%

Tunneling states in vitreousGeO2s

Laermans¹,

Keppens²,

Weeks³

1997

Phys. Rev. B

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“…We also compare both the LDA and BKS results for quartz and stishovite, as well as experimental results for both phases. [67][68][69][70][71][72][73][74] Both the molar volume and compressibility of penta-SiO 2 are intermediate between those of ␣-quartz and stishovite at all pressures. The good agreement between theory and experiment for quartz and stishovite, also shown in previous studies using both LDA ͑Ref.…”

Section: E Stability and Equation Of Statementioning

confidence: 99%

Theoretical study of a five-coordinated silica polymorph

et al. 1997

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Theoretical calculations are performed to study transformations in silica as a function of nonhydrostatic stress. Molecular-dynamics calculations reveal a crystalline-to-crystalline transition from ␣-quartz to a phase with five-coordinated silicon ( V Si) at high pressure in the presence of deviatoric stress. The phase, which appears for specific orientations of the stress tensor relative to the crystallographic axes of quartz, is a crystalline polymorph of silica with five-coordinated silicon. The structure possesses P3 2 21 space-group symmetry. First-principles calculations within the local-density approximation, as well as molecular dynamics and energy minimization with interatomic potentials, find this phase to be mechanically and energetically stable with respect to quartz at high pressure. The calculated x-ray diffraction pattern and vibrational properties of the phase are reported. Upon decompression, the V Si phase reverts to ␣-quartz through an intermediate fourcoordinated phase and an unusual isosymmetrical phase transformation. The results suggest the importance of application of nonhydrostatic stress conditions in the design and synthesis of novel materials.

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“…Hence, the calculation of hole content using Eq. [4] overestimates the carrier content of quadruple perovskites with Ti blocking layers. Later, we will introduce a modi"ed defect model for these compounds that provides a more accurate estimation of Cu oxidation level.…”

Section: Thermogravimetric Analysismentioning

confidence: 94%

“…The TGA-derived hole content (p) in Table 2 is calculated according to Eq. [4] based on the common method used to derive the oxidation level of Cu in known layered cuprate superconductors, as discussed before. In other words, if we assume that oxygen interstitials are not present in signi"cant concentration, the oxygen content should be representative of the carrier concentration.…”

Section: Thermogravimetric Analysismentioning

confidence: 99%