STRUCTURAL RELATIONSHIP BETWEEN VITREOUS P<SUB>2</SUB>O<SUB>5</SUB> AND ITS RELEVANT CRYSTALLINE POLYMORPHS BY RAMAN SPECTROSCOPY

Abstract

Vitreous and relevant crystalline polymorphs of P2O5 have been synthesised and characterised by X-ray diffraction and Raman scattering spectroscopy. On the basis of the crystallographic data of single crystals of the three varieties H-P2O5, O-P2O5 and O'-P2O5, the interpretation of vitreous P2O5 Raman spectrum was given taking into consideration the short and intermediate range order. It inferred that the intermediate range order in v-P2O5 can mainly be described in terms of a mixture of both high temperature modifications, with however predominance of O'-P2O5. This hypothesis has been substantiated by in situ Raman study of v-P2O5 recrystallisation.

Vibrational and structural properties of P2O5 glass: Advances from a combined modeling approach

“…8(a)]; however, the polarizability of terminal oxygens is much stronger than that of bridging oxygens, which leads to their predominance in producing the Raman 640 cm −1 band [see Fig. 8(b)], and this assignment disproves the previous band attribution [14,[16][17][18], which ascribed its origin mainly to the symmetric stretching modes of bridging oxygens. Also, we indicate comparable contributions of bridging oxygen and phosphorus motions and quite moderate contributions of terminal oxygens in the 700-870 cm −1 band; however, the phosphorus atoms contribute lightly to the Raman ∼800 cm −1 band [see the inset in Fig.…”

“…It is also interesting to mention that Raman spectra appearing at 100-550 cm −1 have a structure similar to the VDOS; however, the terminal oxygen contribution is decisive [see Fig. 8(b)] due to higher polarizability, and hence, the Raman modes in the range of 350-550 cm −1 are not specifically related to the bending modes of bridging oxygens [14,16].…”

“…Not only that, at variance with silica-based glasses, phosphate glasses have suitable photodarkening properties [4,5]. Despite the importance of P 2 O 5 glasses in industry and nature and the many theoretical and experimental studies of P 2 O 5 phases [6][7][8][9][10][11][12][13], spectroscopic observations pertinent to the optical and vibrational properties are few [14][15][16][17]. This may explain to some extent why no consensus exists yet about the structure and vibrations of pure P 2 O 5 glass [10].…”

“…By contrast, to our knowledge, a mode assignment in vitreous P 2 O 5 (v-P 2 O 5 ) has been explored by numerical simulations for only specific cluster models [14,15,17,18]. Essentially, it was implied that the typical features of the Raman spectrum of v-P 2 O 5 are three bands [14][15][16][17][18][19]: (i) the phosphoryl stretch band, whose maximum is at ∼1380 cm −1 , (ii) the symmetric stretch of the bridging oxygen band at ∼640 cm −1 , and (iii) the bending mode band appearing at a lower-frequency range of 300-500 cm −1 . However, the cluster model approach is hardly applicable in network glasses due to the impossibility to account for the cooperative effects, the description of which requires more realistic glass models which allow for a proper treatment of long-range effects [20][21][22][23][24][25][26].…”

Structure of binary antimony phosphate glasses by diffraction methods

“…than those of o-P2O5 [33,34]. The reverse Monte Carlo (RMC) simulations of v-P2O5 yielded a bridging angle P−O−P close to 141° [23] which equals that of o'-P2O5 [32].…”