Study of Temperature Behavior of Luminescence Emission of LaVO₄ and La_1-xEu_xVO₄ Powders

Abstract

The La1‑xEuxVO4 powders were synthesized by co-precipitation method. Emission spectra of the LaEuVO4 and La1‑xEuxVO4 powders consist of wide non-structural bands of the matrix emission and narrow spectral lines caused by inner f-f electron transitions in the Eu3+ ions, respectively. The both types of emission were studied within 8 – 300 K temperature range. Decomposition of spectra of the wide matrix emission on three bands has been carried out and temperature dependencies for each band were studied. Temperature behavior of the Eu3+ emission was investigated for lines assigned to different Eu3+ centres. Obtained dependencies are analyzed and discussed using proposed schemes of transitions in the VO43- groups and structure of the nearest surrounding of the Eu3+ emission centres.

Synthesis and Properties of the La1 − x − y Eu y Ca x VO4 (0 ≤ x, y ≤ 0.2) Compounds

“…5). The band positions and structure of the spectra are similar to those described previously as for undoped nanosized LaVO 4 and Ba 3 V 2 O 8 compounds, as well as for activated Sr 2.91 V 2 O 8 :0.06Eu 3+ , Ca 2 NaMg 2 V 3 O 12 :Eu 3+ , and Na 2 LnMg 2 V 3 O 12 vanadate phosphors [17, 21, 39, 40]. The observed bands can be assigned to electron transitions in the VO 4 3− groups; those are constituents of mentioned compounds.…”

“…The observed bands can be assigned to electron transitions in the VO 4 3− groups; those are constituents of mentioned compounds. The charge transfer transitions of 3d orbitals electron of the V 5+ ion to the 2p orbital electron of the O 2− ion inside of the VO 4 3− groups are the nature of this luminescence [40, 41]. According to energy scheme of the vanadate tetrahedron, emission bands at 570 and 630 nm are connected respectively with 3 T 2 and 3 T 1  →  1 A 1 electron transitions in the VO 4 3− groups [39–41].…”

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

“…The observed spectra are complex in nature having several strongly overlapped components, i.e., emerge due to the transitions from a more complicated energy scheme. The observed spectrum for the x = 0 sample is analogous to the earlier reports, where several groups have observed the strongly overlapped bands centered near 540 nm [62,65,66]; how- ever, a small kink near 415 nm is not observed in the literature. The broad peak shape is related to the several d-f transitions of the lanthanum orthovanadate compound [68].…”

“…6(b-f) for the x = 0-0.2 samples, respectively. The position of these four Gaussian peaks (marked by arrows) are taken from the related reference from the literature [25,65,66], while two peaks (marked by vertical lines) in the respective ends are inserted to fit the data with the minimum number of Gaussian peaks. The presence of six peaks in the deconvoluted PL spectra indicate the availability of more than one recombination centers for the electron-hole pairs, as the emission and excitation in these samples are all governed by the VO 3− 4 tetrahedron having the T d symmetry.…”

Pulsed laser deposition of the LaVO4:Eu, Ca nanoparticles on glass and silicon substrates

“…A wide range of possible applications of vanadate nanoparticles have attracted significant research efforts to development of new vanadate compositions with improved characteristics depending on requirements of various practical tasks (Zhu et al, 2018;Chornii et al, 2016;Biswas et al, 2017;Venkatesan et al, 2018;. Studying the Eu 3+ -activated LaVO 4 vanadate nanoparticles, we have achieved increase of emission intensity in 10 times using various synthesis conditions (Chukova et al, 2013(Chukova et al, , 2015(Chukova et al, , 2018. The best intensity characteristics were achieved for the La 1-x Eu x VO 4 nanoparticles synthesized by sol-gel method.…”