Raman investigations of rare earth orthovanadates

Abstract

Polarized Raman spectroscopy has been used to obtain the room-temperature phonon spectra of the series of rare earth orthovanadate single crystals: SmVO4, HoVO4, YbVO4, and LuVO4. The observed Raman frequencies follow the overall mode distribution expected for REVO4 compounds with the tetragonal zircon structure. The variation of the mode frequency with atomic number across the lanthanide orthovanadate series was investigated, and the trend exhibited by the internal modes was explained by considering the force constants of VO4 tetrahedron.

Raman investigations of rare‐earth arsenate single crystals

“…Figure 2 shows plots of the wavenumbers listed in Table 1 versus Z. We observe that the wavenumber of the internal modes of the REAsO 4 (RE = Tb through Lu) increases on average by 2.6%, which is of the same order as the values found for the zircontype REPO 4 (2.1%) and REVO 4 (2.2%) compounds as reported in Refs [15,16], respectively. In the region of the lattice vibrations (ν < 260 cm −1 ), however, the correlation is less evident.…”

“…External modes Refs HoPO 4 1000 1057 1021 655 578 485 -296 182 139 [33] HoAsO 4 895 887 839 507 437 407 236 247 159 131 Present work HoVO 4 891 816 834 487 -380 261 248 156 119 [16] from X-ray measurements reported earlier. [21,25 -31] While the X-O average distance slightly decreases for X = P and V (∼0.3%), it slightly increases for X = As (∼0.4% These results indicate that the decrease of the wavenumber of the internal modes of the AsO 4 may be related to the decrease of the RE-O bond lengths, as proposed by Podor.…”

High-pressure polymorphs of TbVO4: A Raman and ab initio study

“…The symmetry assignment for the Raman modes has been performed in accordance with our calculations and by comparison with previous results in TbVO 4 , altogether summarized in Table I. Our Raman frequencies at ambient pressure agree well with the literature [23,38], being differences in frequencies always within 1%.…”

Phonons in isostructural (ND,Yb):Y Gd1−(VO4) laser crystals: A Raman scattering study

“…The Raman results indicate that the phonon spectra of Nd:GdVO 4 exhibits a relatively small alteration, suggesting that the GdVO 4 lattice is largely insensitive to Nd doping, at least for a Nd concentration of 0.005. In going from NdVO 4 to GdVO 4 the wavenumbers of the internal VO 4 modes increases by 1.7% on average [24], while the observed shift for Nd 0.005 :GdVO 4 is 0.15%. The wavenumbers observed are listed in Table 1, where we also list the wavenumbers of Nd:YVO 4 [31], which are similar to those of YVO 4 [32,35].…”

“…Polarized results can be found for PrVO 4 [16], NdVO 4 [16], GdVO 4 [17], TbVO 4 [17], DyVO 4 [17], and ErVO 4 [18], while unpolarized results can be found for TmVO 4 [19], LaVO 4 [20], CeVO 4 [21], SmVO 4 [22], EuVO 4 [19], HoVO 4 [23], YbVO 4 [19], and LuVO 4 [23]. Recently, Santos et al [24] provided a more accurate description of the room-temperature phonons for SmVO 4 , HoVO 4 , YbVO 4 , and LuVO 4 single crystals. Of the 12 zone-center Raman phonons expected, they observed 10 phonons for SmVO 4 and HoVO 4 and 9 for YbVO 4 and LuVO 4 .…”