skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Synthesis of samarium sesquioxide from the thermal decomposition of samarium oxychloride

Abstract

In this work, Sm{sub 2}O{sub 3} was synthesized from the thermal decomposition of SmOCl (P4/nmm). The process was studied by gravimetry under flowing air between 600 deg. C and 950 deg. C. Reactants and products were identified and analyzed by X-ray diffraction and energy dispersive spectroscopy. From the results, the stoichiometry of the reaction was obtained. Between 800 deg. C and 950 deg. C, the successive formation of both cubic Sm{sub 2}O{sub 3} (Ia3) and monoclinic Sm{sub 2}O{sub 3} (C2/m) phases was observed. Below 800 deg. C, no transformation of cubic Sm{sub 2}O{sub 3} to monoclinic Sm{sub 2}O{sub 3} was detected. Quantification of phases was made using the Rietveld Method. Combined with the analysis of the evolution of the microstructure by scanning electron microscopy, an elemental analysis of the kinetics of the reaction was made and a reaction scheme was proposed.

Authors:
 [1];  [2];  [3];  [4]
  1. Centro Atomico Bariloche, Comision Nacional de Energia Atomica, S.C. de Bariloche (R8402AGP), Rio Negro (Argentina). E-mail: esquivel@cab.cnea.gov.ar
  2. Consejo Nacional de Investigaciones Cientificas y Tecnicas, S.C. de Bariloche (R8402AGP), Rio Negro (Argentina)
  3. Centro Atomico Bariloche, Comision Nacional de Energia Atomica, S.C. de Bariloche (R8402AGP), Rio Negro (Argentina)
  4. (R8402AGP), Rio Negro (Argentina)
Publication Date:
OSTI Identifier:
21000609
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Research Bulletin; Journal Volume: 42; Journal Issue: 3; Other Information: DOI: 10.1016/j.materresbull.2006.06.012; PII: S0025-5408(06)00255-8; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CHEMICAL PREPARATION; GRAVIMETRY; MICROSTRUCTURE; MONOCLINIC LATTICES; OXYCHLORIDES; PYROLYSIS; SAMARIUM CHLORIDES; SAMARIUM OXIDES; SCANNING ELECTRON MICROSCOPY; SPECTROSCOPY; STOICHIOMETRY; TETRAGONAL LATTICES; X-RAY DIFFRACTION

Citation Formats

Esquivel, M.R., Bohe, A.E., Pasquevich, D.M., and Consejo Nacional de Investigaciones Cientificas y Tecnicas, S.C. de Bariloche. Synthesis of samarium sesquioxide from the thermal decomposition of samarium oxychloride. United States: N. p., 2007. Web. doi:10.1016/j.materresbull.2006.06.012.
Esquivel, M.R., Bohe, A.E., Pasquevich, D.M., & Consejo Nacional de Investigaciones Cientificas y Tecnicas, S.C. de Bariloche. Synthesis of samarium sesquioxide from the thermal decomposition of samarium oxychloride. United States. doi:10.1016/j.materresbull.2006.06.012.
Esquivel, M.R., Bohe, A.E., Pasquevich, D.M., and Consejo Nacional de Investigaciones Cientificas y Tecnicas, S.C. de Bariloche. Thu . "Synthesis of samarium sesquioxide from the thermal decomposition of samarium oxychloride". United States. doi:10.1016/j.materresbull.2006.06.012.
@article{osti_21000609,
title = {Synthesis of samarium sesquioxide from the thermal decomposition of samarium oxychloride},
author = {Esquivel, M.R. and Bohe, A.E. and Pasquevich, D.M. and Consejo Nacional de Investigaciones Cientificas y Tecnicas, S.C. de Bariloche},
abstractNote = {In this work, Sm{sub 2}O{sub 3} was synthesized from the thermal decomposition of SmOCl (P4/nmm). The process was studied by gravimetry under flowing air between 600 deg. C and 950 deg. C. Reactants and products were identified and analyzed by X-ray diffraction and energy dispersive spectroscopy. From the results, the stoichiometry of the reaction was obtained. Between 800 deg. C and 950 deg. C, the successive formation of both cubic Sm{sub 2}O{sub 3} (Ia3) and monoclinic Sm{sub 2}O{sub 3} (C2/m) phases was observed. Below 800 deg. C, no transformation of cubic Sm{sub 2}O{sub 3} to monoclinic Sm{sub 2}O{sub 3} was detected. Quantification of phases was made using the Rietveld Method. Combined with the analysis of the evolution of the microstructure by scanning electron microscopy, an elemental analysis of the kinetics of the reaction was made and a reaction scheme was proposed.},
doi = {10.1016/j.materresbull.2006.06.012},
journal = {Materials Research Bulletin},
number = 3,
volume = 42,
place = {United States},
year = {Thu Mar 22 00:00:00 EDT 2007},
month = {Thu Mar 22 00:00:00 EDT 2007}
}
  • Graphical abstract: - Highlights: • The cubic Gd{sub 2}O{sub 3} nanobars are synthesized by decomposition of C{sub 6}H{sub 20}Gd{sub 2}O{sub 22}. • The nanoparticles are rectangular bar shape with high porous surface. • The combination of magnetic and optical properties within a single particle. • The Gd{sub 2}O{sub 3} nanobars have tailorable nanostructure, wide bandgap and are paramagnetic. - Abstract: Gadolinium oxide nanobars were obtained by thermal decomposition of gadolinium oxalate, which was synthesized by the chemical precipitation method along with glycerol. The functional group analysis and formation of gadolinium oxide from gadolinium oxalate were characterized by the Fourier transformmore » infrared spectroscopy and thermo gravimetric analyzer. The crystal structure, average crystallite size, and lattice parameter were analyzed by X-ray diffraction technique. Moreover, Raman shifts, elemental composition and morphology of the gadolinium oxide was widely investigated by the laser Raman microscope, X-ray photoelectron spectroscopy, FE-SEM-EDAX and HR-TEM, respectively. Furthermore, the optical properties like band gap, absorbance measurement of the gadolinium oxide were extensively examined. In addition, the paramagnetic property of gadolinium oxide nanobars was explored by the vibrating sample magnetometer.« less
  • Single-phase anatase-TiO2 nanomaterials with a size of ca. 10 nm and variable quantities of anion impurities were prepared using a novel pathway based on the use of amorphous ammonium Ti-oxychloride precursors synthesized using Ti/Cl initial ratios between 1 and 6. The precursor nature and evolution under thermal treatment were studied using chemical analysis, XRD, XPS, DRIFTS, and mass spectrometry. The nature and concentration of anatase-TiO2 materials anion impurities were analyzed by XPS and DRIFTS. It is shown that negatively charged impurities located in substitutional positions of the anatase network are maximized for a sample synthesized using a Ti/Cl 1:1 atomicmore » ratio and are responsible for the elimination of liquid-phase (phenol) and gas-phase (isopropanol or methylcyclohexane) pollutants under sunlight excitation. A link is established among the initial chemical characterization of the precursors, the final morphological, structural, and chemical composition of the oxide materials, and their photochemical properties.« less
  • The magnesia-supported bismuth oxychloride with lithium carbonate present is significantly more effective and stable with time-on-stream than the unsupported or supported systems free of Li[sub 2]CO[sub 3] in the oxidative coupling of methane at 750[degrees]C, P[sub CH[sub 4]] = 20.2 kPa, CH[sub 4]/O[sub 2] = 4, and a space velocity of 15,000 cm[sup 3] g[sup [minus]1] h[sup [minus]1]. The most effective catalytic system is obtained when 10 mol% BiOCl is supported on MgO with 10 mol% Li[sub 2]CO[sub 3], which leads to a methane conversion of 18%, C[sub 2] selectivity of 83%, and an ethylene-to-ethane molar ratio of 2.9 formore » at least 12 h under the aforementioned conditions and atmospheric pressure. The unsupported or supported samarium chloride free of Li[sub 2]CO[sub 3] was less effective under similar conditions. Only when the samarium chloride and lithium carbonate contents on the support were sufficiently increased (28 and 40 mol%, respectively) the system became effective towards high C[sub 2] selectivity and stability. In contrast, none of the manganese-chloride-based systems exhibited good C[sub 2] selectivity and stability except initially, but they mainly promoted the reaction of methane to carbon oxides. The introduction of Li[sub 2]CO[sub 3] is found to retard the loss of surface chlorine and prevent the decrease of surface bismuth and samarium, resulting thereby in more stabilized systems. In addition, the bulk and surface modifications, which are more prominent in the presence of Li[sub 2]CO[sub 3], caused by calcination and reaction conditions are believed to influence the formation of the catalytically active or inactive sites. The performance of the catalysts is related to its surface composition, bulk modification, decomposition, and reducibility of the metal chlorides or oxychloride on the basis of XPS, XRD, SEM, and thermal analysis (TPD and TPR) investigations. 59 refs., 9 figs., 8 tabs.« less