Correlation between Raman wavenumbers and P?O bond lengths in crystalline inorganic phosphates

Abstract

A linear empirical correlation was established between Raman stretching wavenumbers of phosphorus-oxygen bonds and their bond lengths in inorganic crystalline phosphates. Although established on samples of inorganic crystalline phosphates, the correlation can be applied to glassy and amorphous phosphate materials (GAMs). Their unpolarized vibrational spectra are often similar because they are determined largely by short-range order. The correlation was used to predict P -O bond length in the a-form of Li 3 PO 4 , which is stable over only a small range of temperatures below the melting-point. It can also be used to estimate the length of P -O single bonds, terminal P -O and O -P -O chain bonds and terminal double bonds in many technologically important amorphous materials containing phosphate groups. This correlation is expected to offer invaluable insight into the structures of phosphate species for which diffraction or other spectroscopic techniques provide incomplete structural information. That would enhance the value of Raman spectroscopy as a complementary technique in structural studies of phosphates.

Production of titanium–tin alloy powder by ball milling: Formation of titanium–tin oxynitride composite powder produced by annealing in air

“…9b. A Raman peak appearing at 574 and 580 cm À1 is well-known as A 1g mode intensity arises either as a consequence of increase in the surface-to-volume atom ratio or due to conversion from crystalline to nanocrystalline induced by increasing disordered atoms by milling [22]. These intensity peaks of the TGA sample are comparable to those obtained after Raman analysis of the TGA powder for the pre-annealed sample (Fig.…”

Untitled

“…The shifts however, observed between our vibrational frequencies and those reported by Harada et al (1971), Arkhipenko and Moroz (1997), and Socrates (2001) reflect the partial substitution of (SiO 4 ) 4-and (SO 4 ) 2-for the (PO 4 ) 3-group in the apatite structure. Based on Santos and Clayton (1995) and Popović et al (2005), the IR bands at 1144 and 1049 cm -1 from our spectrum were assigned to either double or single bond stretching of an orthophosphate and not to the (SO 4 ) 2-group as suggested by Harada et al (1971) and Sejkora et al (1999).…”

Direct femtosecond laser waveguide writing inside zinc phosphate glass

“…Popovic et al have shown that the positions of Raman peaks from crystalline inorganic phosphates correlates with the P-O bond length, where generally longer bonds are associated with lower wavenumbers [25]. If a similar correlation exists for the modified zinc phosphate glasses, then the decrease in the (PO 2 ) sym peak position of the modified glasses shown in Fig.…”