Piccinelli F, Carrasco I, Ma CG, Bettinelli M. Systematic Analysis of the Crystal Chemistry and Eu
3+ Spectroscopy along the Series of Double Perovskites Ca
2LnSbO
6 (Ln = La, Eu, Gd, Lu, and Y).
Inorg Chem 2021;
60:8259-8266. [PMID:
34019423 PMCID:
PMC8277163 DOI:
10.1021/acs.inorgchem.1c00932]
[Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Eu3+ (1
mol %)-doped Ca2LnSbO6 (replacing Ln3+; Ln = Lu, Y, Gd, and La) and Ca2EuSbO6 were
synthesized and structurally characterized
by means of X-ray powder diffraction. The Eu3+ luminescence
spectroscopy of the doped samples and of Ca2EuSbO6 has been carefully investigated upon collection of the excitation/emission
spectra and luminescence decay curves of the main excited states.
Surprisingly, apart from the dominant red emission from 5D0, all the doped samples show an uncommon blue and green
emission contribution from 5DJ (J = 1, 2, and 3). This is made possible thanks
to both multiphonon and cross-relaxation mechanism inefficiencies.
However, the emission from 5D3 is more efficient
and the decay kinetics of the 5DJ (J = 0, 1, and 2) levels is slower in the case
of Y- and Lu-based doped samples. This evidence can find a possible
explanation in the crystal chemistry of this family of double perovskites:
our structural investigation suggests an uneven distribution of the
Eu3+ dopant ions in Ca2YSbO6 and
Ca2LuSbO6 hosts of the general A2BB′O6 formula. The luminescent center is mainly
located in the A crystal site, and on average, the Eu–Eu distances
are longer than in the case of the Gd- and La-based matrix. These
longer distances can further reduce the efficiency of the cross-relaxation
mechanism and, consequently, the radiative transitions are more efficient.
The slower depopulation of Eu3+ 5D2 and 5D1 levels in Ca2YSbO6 and
Ca2LuSbO6 hosts is reflected in the longer rise
observed in the 5D1 and 5D0 decay curves, respectively. Finally, in Ca2EuSbO6, the high Eu3+ concentration gives rise to an
efficient cross-relaxation within the subset of the lanthanide ions
so that no emission from 5DJ (J = 1, 2, and 3) is possible and the 5D0 decay kinetics is faster than for the doped samples.
Eu3+ as a dopant ion in the
series of double
perovskite Ca2LnSbO6 (Ln = La, Gd, Y, and Lu)
hosts shows a different occupation of the available A and B crystal
sites; this strongly affects the luminescence behavior in the visible
spectral region.
Collapse