ChemInform Abstract: Crystal Growth, Structure, and Properties of KLa(CrO4)2.

Abstract

ChemInform Abstract The title compound (III), prepared as shown in the scheme, crystallizes in the space group P21/c with Z=4. The structure consists of parallel layers of (La(CrO4)2)n-n perpendicular to the a-axis, K+ being located between these layers. IR and Raman spectra are reported. In contrast to previously reported results, the thermal decomposition is found to proceed in one step according to the scheme.

Spectroscopic Study of Rare Earth Chromates: Relation to the Structure

“…We report here the optical properties and the simulation of the energy level scheme of trivalent europium ion embedded in the rare earth chromates studied and discuss their relation to the crystal structures previously determined [1][2][3][4]. The present work underlines the sensitivity of the spectroscopy for the characterization of new phases.…”

“…At the end of the rare earth series a third structural modification was found and determined as monoclinic one [6]. The optical analysis were not realized on that series.…”

“…Seven hydrated rare earth chromate phases with a general formula RE2(CrO4)3 , 7H2O, exist for RE = La-Gd. The single crystals were grown by hydrothermal procedure from an aqueous solution of rare earth oxide, chromium oxide and lithium hydroxide in molar ratios 1:4:3, respectively, for 4 hours at 125°C [4]. The compounds exhibit the monoclinic structure, space group Ρ21/n, with two different crystallographic sites for the rare earth atoms both in nine coordination (Fig.…”

“…Therefore, in the ternary system RΕ 2 O3-CrO3-M 2 O (RE = rare earth, M = alkali metal) different chromates studied here by luminescence spectroscopy are the following: double chromates with the potassium, KRE(CrO 4 ) 2 , [1,2]; hydroxo-chromates, RΕ(OH)CrO 4 , [3] and seven hydrated chromates RE2 (CrO4 )3 , 7H 2 O [4]. They crystallize in the monoclinic or orthorhombic system and the rare earth atom is situated in one point site of very low symmetry in all these chromates except in the last one for which two different environments were found for the lanthanide ion.…”

Nd2(OH)2(CrO4)2 and [Tb2(CrO4)3(H2O)5].2H2O

“…At the moment six structures are known for rare-earth chromates: [Ln2(CrO4)3(H20)5].2H20 [Ln = Nd, Eu (Leppfi-aho & Valkonen, 1991), La (Habekost, Christensen & Hazell, 1991) and Sm (Bueno, Parada, Monge & Ruiz-Valero, 1991a (Bueno, Parada, Garcia, Puebla, Monge & RuizValero, 1989); Ce(CrO4)>2H20 (Lindgren, 1977); Ln3(OH)(CrO4)4.3.5H20…”