Structural phase transition and its consequences on optical behavior of LaV${}_{1-x}$Nb${}_x$O${}_4$

Abstract

We present the structural, electronic, vibrational, and photoluminescence properties of polycrystalline LaV${}_{1-x}$Nb${}_x$O${}_4$ ($x=$ 0--0.2) samples at room temperature. The substitution of Nb at the V site shows the fascinating structural and optical behavior due to their isoelectronic character and larger ionic radii of Nb${}^{5+}$ as compared to the V${}^{5+}$. The Rietveld refinement of x-ray diffraction patterns demonstrate that the $x=$ 0 sample exist in a monoclinic (P2${}_1$/n) phase, whereas for the $x>$ 0, both monoclinic and scheelite-tetragonal (I4${}_1$/a) phases co-exist in a certain proportion. Interestingly, a monotonous enhancement in the Raman spectral intensity with Nb substitution is correlated with the substitution induced increase in the scheelite-tetragonal phase. The x-ray absorption measurements reveal that the La ions exist in a trivalent oxidation state, while V and Nb cations possess 5+ oxidation state in tetrahedral coordination. Moreover, the Fourier-transform infrared (FTIR) spectra indicate that the Nb substitution give origin to some additional IR modes owing to the deformation of the VO${}_4$${}^{3-}$ tetrahedra and mixing of monoclinic and tetragonal phases. The photoluminescence measurements on these samples exhibit broadband spectra and their deconvolution designate the availability of more than one electron-hole pairs recombination center.

arXiv commentsubmitted

References in corpus (8)

• The electronic structure of zircon-type orthovanadates: Effects of high-pressure and cation substitution
• Recent progress on the characterization of the high-pressure behaviour of AVO4 orthovanadates
• High-pressure structural investigation of several zircon-type orthovanadates
• In situ high-pressure synchrotron x-ray diffraction study of CeVO4 and TbVO4 up to 50 GPa
• Zircon to monazite phase transition in CeVO4
• Na-ion diffusion and electrochemical performance of NaVO${}_3$ anode in Li/Na batteries
• Phase stability of lanthanum orthovanadate at high-pressure
• Breaking the Selection Rules of Spin-Forbidden Molecular Absorption in Plasmonic Nanocavities

Cited by in corpus (2)

• In situ study of zinc peroxide decomposition to zinc oxide by X-ray absorption spectroscopy and reverse Monte-Carlo simulations
• Investigation of lattice dynamics, magnetism and electronic transport in $\beta$-Na${}_{0.33}$V${}_2$O${}_5$