G. Gauthier et al., Synthesis, structure and electronic properties of the cerium and potassiumthiosilicate: KCeSiS4, CR AC S IIC, 2(11-13), 1999, pp. 611-616
Citations number
24
Categorie Soggetti
Chemistry
Journal title
COMPTES RENDUS DE L ACADEMIE DES SCIENCES SERIE II FASCICULE C-CHIMIE
The cerium and potassium thiosilicate KCeSiS4 has been synthesized at 800 d
egrees C from Ce, Si, K2S and S precursors weighted in the K:Ce:Si:S = 1:1:
1.15:4.3 ratio. This yellow, air stable compound crystallizes in the monocl
inic space group P2(1) (No. 4) with the cell parameters: a = 6.5201(3) Angs
trom, b = 6.5982(3) Angstrom, c = 8.6320(5) Angstrom, beta = 107.701(3)degr
ees, V = 356.23(3) Angstrom(3) and Z = 2. Refinement of 36 parameters by th
e Rietveld method, using 974 reflections led to R-p (%) = 2.49, R-wp (%) =
3.35 and chi(2) = 2.71. KCeSiS4, isostructural to KLnMQ(4) (Ln = La, Nd, Gd
, Y; M = Si, Ge; Q = S, Se), consists of two-dimensional (2)(infinity)[CeSi
S4](-) anionic layers separated by Kf ions. These layers are built upon [Ce
S7] distorted monocapped trigonal prisms, sharing 2 edges and 2 corners wit
h each other, and upon [SiS4] tetrahedra linked to the (2)(infinity)[CeS4](
5-) skeleton by edge and face sharing. From magnetic measurements, an effec
tive magnetic moment mu(eff)(300 K) = 2.73(2) mu(B) was calculated in good
agreement with the (KCe(III)SiS4(-II))-Ce-(I)-S-(IV) charge balance. From d
iffuse reflectance measurements, a band gap of 2.68(1) eV correlated to the
occurrence of a 4f--> 5d electronic transition was evidenced. Moreover, ch
romatic L/a/b coefficients, equal respectively to 88.37/-18.85/52.91, have
been determined for the bright yellow colour of the compound. These paramet
ers compare rather well with those of NiTiO3, a well known industrial pigme
nt. The room temperature strong green luminescence at E = 2.45 eV (lambda =
506.1 nm) of KCeSiS4 has been investigated through emission and excitation
spectroscopy in the W-visible range. (C) 1393 Academie des sciences / Edit
ions scientifiques et medicales Elsevier SAS.