Applications of Phosphorene and Black Phosphorus in Energy Conversion and Storage Devices

Thirty different binary metal oxide glasses having the metaphosphate composition have been prepared containing cations from the following groups: alkali metals, alkaline earths, transition metals, and lanthanide and actinide metals. Far infrared absorption assigned to the cation vibration in its oxygen cage has been measured for these glasses. Empirical ionic models are proposed correlating the absorption maximum with the cation mass, charge, and ionic radius. Discrepancies between the observed and predicted vibrational frequency indicate a more covalent interaction between the metal cation and the glass network. Raman intensities and vibrational frequencies of the network metaphosphate vibrations have been obtained and provide additional evidence about the cation–site interaction.

Vibrational spectroscopy of cation‐site interactions in phosphate glasses

Types of “H2O” in human enamel and in precipitated apatites are characterized using X-ray diffraction, infrared (IR) absorption spectroscopic and thermogravimetric analyses. Changes in lattice parameters (principally in the α-axis dimensions) and in the character of the IR absorption bands are correlated with weight losses at pyrolysis temperatures of 100° to 400°C and with effect of rehydration and reignition of previously ignited samples.

Types of "H2O" in human enamel and in precipitated apatites.

The results and detailed discussion of an extensive experimental study of infrared spectra of the x (PbO)-(1−x)P2O5 vitreous system (x=0.3–0.75) together with a brief review of infrared spectra of phosphate compounds, are presented. Theoretical models employed in the interpretation of infrared spectra of glasses have been reviewed. The frequency ranges of various infrared bands belonging to PO
 4
 3−
 and P2O
 7
 4−
 , observed in different phosphate compounds, are discussed. The glassy and quenched samples were prepared from PbO and NH4H2PO4 by the rapid quenching technique. The infrared spectra of the constituents of the system, PbO and P2O5, in their polycrystalline and glassy forms, have been discussed. The intensity and wavenumbers of the infrared bands around 1600 and 3300 cm−1, assigned to the bending and stretching modes in H2O trapped by the hygroscopic glasses, have been followed for different compositions with x<0.5. The changes observed in these infrared bands established the role of water as an additional glass modifier. The intensity and frequency variations of the infrared bands have been followed through all the compositions for characteristic phosphate group frequencies including P=O, P-O-P stretching and bending modes and P-O bending mode. The results clearly suggest that the x(PbO)-(1−x)P2O5 system undergoes gradual structural changes from metaphosphate (x=0.5), to pyrophosphate (x=0.66) and to orthophosphate (x=0.75). The continuing presence of the infrared band, in varying intensity, in the region 1200–1280 cm−1 attributed to P=O, suggests that the glass-forming ability of the binary system is extendable at least up to x=0.66 composition, and that no complete rupture of P=O bond by Pb2+ takes place. The ionic character of the phosphate groups, P-O(−), PO
 4
 3−
 is well revealed by significant changes with the PbO content in the spectral features of the infrared bands around 1120 and 980 cm−1 respectively. The maximum intensity of the P-O(−) band at 1120 cm−1 for 55 mol% PbO suggests a partial breakdown of the covalent vitreous network of the phosphates and formation of a crystalline phase consisting of ionic groups PO
 4
 3−
 , P2O
 6
 2−
 and P2O
 7
 4−
 for PbO greater than 55 mol%. The observed pattern of variation in the intensity of the infrared bands in the 940–1080 cm−1 region attributed to the v3-mode in PO
 4
 3−
 , suggests a gradual transformation of PO
 4
 3−
 units to PO
 3
 −
 groups in lead meta-phosphate glass and then their restoration to PO
 4
 3−
 groups of pyro- and ortho-phosphate quenched samples. The results indicate a gradual decrease in the number of bridging oxygens and increase in the resonance behaviour of non-bridging oxygens as the mole percentage of metal oxide (PbO) increases in the glass. The infrared spectra of several binary phosphate glasses have been reviewed in the context of the study of effect of the cation on the infrared spectra. It is found that the influence of the cation on the infrared spectra of phosphate glasses does not show any striking regularity. Theoretical calculations of these band frequencies were found to agree well only in the case of pure stretching (P=O and O-H) vibrations and pure bending (P-O-P and O-H) vibrations. The disagreement in the case of P-O(−), P-O-H and other modes of P-O-P groups, has been attributed to the mixed nature of modes occurring in glasses. The changes in the positions of the characteristic bands and their relative intensities are strongly dependent on the structural units and PbO content in the phosphate glasses and the results emphasize the role of PbO as a network modifier.

Structural investigations of phosphate glasses: a detailed infrared study of the x(PbO)-(1−x) P2O5 vitreous system

A spectra-structure correlation chart for phosphorus compounds is presented, and the existing evidence for these correlations is summarized



Powdered phosphate salts absorb in a number of discrete regions which are characteristic of the type of anion present The use of this data for qualitative identification is discussed, and examples are given of the use of the pressed disc technique for quantitative work

D. E. C. Corbridge

Papers

The infra-red spectra of some inorganic phosphorus compounds