Lattice dynamics of Hittorf's phosphorus and identification of structural groups and defects in amorphous red phosphorus

Fasol, Gerhard; Cardona, M.; Hönle, Wolfgang; Schnering, H. G. von

doi:10.1016/0038-1098(84)90832-9

Cited by 83 publications

(55 citation statements)

References 11 publications

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“…It is noteworthy that the configuration in Fig. 3 is very similar to that of the Pg cluster found in Hittorf (and amorphous) P, 22 and the vibrational characteristics would therefore be expected also to be very similar. It is proposed, therefore, that such phosphorus clusters are the origin of the 278-cm" 1 peak in the VDOS of g-Po.67Seo.33.…”

Section: Scme) -E ~2 W H Q Inj + Dgiqe)supporting

confidence: 57%

Experimental Evidence for an Inorganic Molecular Glass

Verrall

Elliott²

1988

Phys. Rev. Lett.

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Inelastic neutron-scattering experiments have been performed for the first time on glassy phosphorusselenium alloys. The effective density of vibrational states so obtained is highly structured in the case of glassy Po.67Seo.33 and provides evidence for the existence of molecular clusters in the structure based predominantly on P4Se3 units, i.e., a "zero-dimensional" glass. PACS numbers: 61.40.+b, 61.12.Ex, 63.50.+XThe atomic-scale structure of glasses, particularly concerning medium-(or intermediate-) range order, is still a very contentious issue. One useful way of approaching this problem for the case of inorganic glasses is in terms of the local network dimensionality. 1 Thus, a "zerodimensional" (OD) structure corresponds to a molecular glass whose structure is (ideally) composed entirely of discrete molecular species. 2 The interest in such materials lies in the fact that for these the local short-range structure is well defined and so its influence on the medium-range order can be assessed. However, until now there has been no direct experimental evidence for the existence of such stable OD structures in the bulk glassy phase for inorganic materials. There is evidence, e.g., from photoemission, 3 that, for example, evaporated thin films of As x Six are composed primarily of AS4S4 molecular clusters; however, these films are extremely unstable and, upon annealing or exposure to light, polymerize readily to form a cross-linked network very similar to that of the bulk glass. In addition, sharp peaks have been observed in the Raman spectra of certain inorganic bulk glasses, for example B2O3 (Ref. 4) and GeSe2 (Ref. 5), perhaps indicative of decoupled molecular modes; however, the vibrational densities of states (VDOS) for B2O3 (Ref. 6) and GeSe 2 (Ref. 7) do not exhibit correspondingly sharp intense features, indicating that molecular characteristics, if responsible, are not a dominant structural motif.It is interesting, therefore, that recently Price and coworkers 8,9 have suggested, on the basis of (elastic) neutron-scattering, extended x-ray absorption fine structure, and Raman scattering results on selenium-rich phosphorus selenide glasses, that the system P x Seix might be a possible candidate for such OD amorphous structures. With this in mind, we have undertaken the first inelastic neutron-scattering studies of P x Seix glasses, in particular, investigating the previously unstudied phosphorus-rich compositions. (In addition, elastic neutron diffraction experiments have been carried out on the same compositions. 10 ) The motivation behind such studies has been to obtain information on the VDOS, unaffected by the matrix-element effects which occur in Raman scattering. A signature of vibrationally decoupled molecular clusters comprising a molecular (OD) glass is expected to be a vibrational spectrum exhibiting characteristically narrow peaks corresponding to the individual vibrational modes of the clusters, unbroadened by coupling of these modes to the rest of the structure.The PxSei-* system forms glasses...

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Section: Scme) -E ~2 W H Q Inj + Dgiqe)supporting

confidence: 57%

Experimental Evidence for an Inorganic Molecular Glass

Verrall

Elliott²

1988

Phys. Rev. Lett.

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“…Film optical constants (n, k) and the thickness were derived using a model of amorphous semiconductor on 0.5 mm thick crystalline Si, with the semiconductor layer described using the Tauc-Lorentz model. 28 All P-DLC films grown in this work were found to have a smooth, apparently featureless surface morphology apart from some randomly dispersed micron size particulates, which we assume to be crystallites that have transported directly from the target following explosive melting of the target surface. The thickness of the deposited P-DLC films was observed to increase with increasing F. For example, in the case of films deposited for 20 min at T sub = 298 K, the thickness was found to increase from ∼30 nm (for F = 4 J cm Ϫ2 ) to ∼50 nm (F = 12 J cm Ϫ2 ).…”

Section: Methodsmentioning

confidence: 73%

Phosphorus carbides: theory and experiment

et al. 2004

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The recent finding that radio frequency plasma activation of CH 4 /PH 3 gas mixtures can yield films with P : C ratios ≤ 3 has served to trigger further research into new 'phosphorus carbide' materials. Theoretical and experimental results relating to periodic and amorphous materials, respectively, are presented here: (i) The electronic structure and stability of different crystalline phosphorus carbide P x C y phases have been studied using first-principles densityfunctional theory. Calculations have been carried out for P 4 C 3ϩ8n (n = 0-4), PC, and PC 3 and the most likely periodic structures examined in detail. Particular attention is paid to the composition PC 3 , for which there are several possibilities of similar energy. (ii) Recent experimental efforts have involved use of pulsed laser ablation methods to produce hydrogen-free phosphorus carbide thin films. Mechanically hard, electrically conducting diamond like carbon films containing 0-∼26 at.% P have been deposited on both Si and quartz substrates by 193 nm PLA of graphite/phosphorus targets (containing varying percentages of phosphorus), at a range of substrate temperatures (T sub = 298-700 K), in vacuum, and analysed via laser Raman and X-ray photoelectron spectroscopy.

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“…To the best of our knowledge, no 31 P NMR data of P r have been published so far. The most obvious reason is the amorphous character of P r [34][35][36]. As a consequence, a large 31 P chemical shift anisotropy is to be expected, including large distributions in the principal axis chemical shift tensor values, which will severely broaden the NMR signals of the individual P sites in the amorphous structure.…”

Section: Solid Residues Of the Binary Mixtures Mg(oh) 2 /P R In Air Omentioning

confidence: 99%