Crystalline hydroxychlorides, Ln(OH)2Cl, of the rare-earth elements of the cerium group

Solvothermal treatment of rare earth chloride hydrates

“…Both the spectra of the products did not show characteristic bands due to the organic residue, but showed two sharp bands around 3600 cm −1 due to the stretching vibration modes of structural OH groups. Klevstov et al reported that the interaction between OH group and Cl in hydroxychloride contributed to these peaks [9]. A broad band at around 3400 cm −1 observed in Group B products seems to be due to the water molecules, suggesting that the unknown phase in Group B products contained a larger amount of structural water molecules.…”

Preparation of CeSiO4 from aqueous precursors under soft hydrothermal conditions

“…Ce(OH) 2 Cl is isostructural to Ln(OH) 2 Cl phases which were formed under hydrothermal conditions in experimental conditions close to those developed in this study. 57,58 Due to its high solubility in nitric acid, a washing step of 10 minutes with 1 M nitric acid after the synthesis allowed to dissolve specifically the Ce(OH) 2 Cl phase leading to a CeSiO 4 and CeO 2 mixture (Figure 9). The direct comparison of the results obtained in nitric and hydrochloric media showed that oxidation of cerium(III) to cerium(IV) necessary to form CeSiO 4 was not only due to the presence of nitrate ions.…”

Investigation of the Structural Properties of an Extended Series of Lanthanide Bis-hydroxychlorides Ln(OH)2Cl (Ln = Nd−Lu, except Pm and Sm)

“…Although the majority of these compounds have been described previously, we reinvestigated most of these complexes and determined the X-ray single crystal structures all at the same temperature of ∼141 K. We were unable to obtain suitable products and single crystals of the Ce, Pr, and Sm compounds. Therefore, we use previously published crystal structure data by Klevtsov et al and Klevtsova et al , to enable us to compare the unit cell parameters along the entire lanthanide series (except for promethium) and correlate observed trends to the decreasing ionic radius throughout the 4f element series. Since these authors do not make any statements about the temperature at which they performed their data collection, we assume that their data were collected at room temperature, as it was probably most commonly done at the time of their publication.…”

“…The synthesis of most lanthanide bis-hydroxychlorides, including crystallographic data, have been described by various scientists. Klevtsov et al − reported the hydrothermal synthesis of the crystalline lanthanide bis-hydroxychlorides and their characterization via X-ray powder diffraction. Other authors performed X-ray single crystal structural studies on the La, Pr, Sm, Gd, and Nd , species.…”

“…Other authors performed X-ray single crystal structural studies on the La, Pr, Sm, Gd, and Nd , species. These workers determined that all of the bis-hydroxychlorides investigated were isostructural with monoclinic Y(OH) 2 Cl. − However, some of these compounds were also found to crystallize in the orthorhombic crystal system with the space group Pnma . ,,, All of these compounds were synthesized under various hydrothermal conditions, by reacting the rare earth oxides with FeCl 3 and/or NH 4 Cl at temperatures between 300 and 600 °C. , These workers also isolated additional products such as Ln 3 O(OH) 5 Cl 2 and LnOOH at these temperatures. Carter et al found that the Ln(OH) 2 Cl compounds are insoluble in water and dissolve very slowly in 6 M hydrochloric acid solutions at room temperature.…”