12014-56-1Relevant articles and documents
Syntheses and crystal structures of hydrated ternary cerium sulfates: Mixed-valence K5Ce2(SO4)6· H2O and K2Ce(SO4)3·H 2O
Casari, Barbara M.,Langer, Vratislav
, p. 1055 - 1061 (2007)
A new chemical and structural interpretation of K5Ce 2(SO5)5·H2O (I) and a redetermination of the structure of K2Ce(SO4) 3·H2O (II) is presented. The mixed-valent compound I crystallizes in the space group C2/c with a = 17.7321(3), b = 7.0599(1), c = 19.4628(4) A, β = 112.373(1)° and Z = 4. Compound I has been discussed earlier with space group Cc. In the structure of I, there are pairs of edge sharing cerium polyhedra connected by sulfate oxygen atoms in the μ3 bonding mode. These cerium dimers are linked through edge and corner sharing sulfate bridges, forming layers. The layers are joined by potassium ions which together with the water molecules are placed between the layers. No irregularity in the distribution of the CeIII and Ce IV to cause the lost of a crystallographic center of symmetry was detected. We suggest that the charge exerted by the extra fI electron for every cerium dimer is delocalized over the Ce1-O2-Ce2 moiety in a non-bonding mode. As a result, the oxidations state of each cerium ion is a mean value between III and IV at each atomic position. Compound II crystallizes in the space group C2 with a = 20.6149(2), b = 7.0742(1), c = 17.8570(1) A, β = 122.720(1)° and Z = 8. The hydrogen atoms have been located and the absolute structure has been established. Neither hydrogen atom positions nor anisotropic displacement parameters were given in the previous reports. In compound II, the cerium polyhedra are connected by edge and corner sharing sulfate groups forming a three-dimensional network. This network contains Z-shaped channels hosting the charge compensating potassium ions.
Hydrolysis of lanthanide dicarbides. Rates of reaction with water
McColm, I. J.,Quigley, T. A.,Bourne, D. R.
, p. 191 - 198 (1991)
The kinetics of the reaction between liquid water and nine lanthanide dicarbides and YC2 have been investigated by monitoring the gas evolved into a constant volume apparatus. The ratio of volume of gas-evolved to that predicted was found to be consistent at 0.51 for wholly trivalent dicarbides, but rose to 0.66 for the light lanthanides containing LnIV components. Only linear kinetics were observed with the linear reaction rate constant KL in the range 0.44 cm cm-2 min-1 for LuC2 to 6.9 cm cm-2 min-1 for CeC2. Over the limited temperature range 283-303.5 K it was possible to estimate activation energies for four of the dicarbides and the values ranged from 48.5 kj mol-1 for the heavy, hard carbides to 150 kJ mol-1 for the light, soft, LnIV-containing members. The variation of KL and E across the series is discussed in terms of M-C2 bond energies, 4f-band electron density and the hardness of these dicarbides.
Influence of the incorporation of CeO2 nanoparticles on the ion exchange behavior of dodecylsulfate doped polypyrrole films: Ac-electrogravimetry investigations
Benmouhoub,Agrisuelas,Benbrahim,Pillier,Gabrielli,Kadri,Pailleret,Perrot,Sel
, p. 270 - 280 (2014)
Cerium oxide (CeO2) nanoparticles (NPs) possessing defined size and crystallinity have been synthesised by a co-precipitation method. The effect of several parameters, such as the nature of the solvent and the calcination process, on the crystallite size was studied by XRD, TEM and BET methods. These CeO2 nanoparticles were then incorporated in dodecylsulfate (DS) doped PPy films during their electrodeposition in potentiodynamic conditions in order to produce PPy-DS/CeO2 NPs nanocomposite thin films on gold coated quartz crystals. Simultaneous EQCM experiments revealed successful incorporation of increasing amounts of cerium oxide nanoparticles in the polypyrrole matrix during each of the consecutive CV scans. This was confirmed using FEG-SEM and EDS microanalysis. The ion exchange phenomena occurring in the resulting nanocomposite materials were studied by ac-electrogravimetry in NaCl aqueous electrolyte. PPy-DS films appear to be mainly cation exchangers, independently from the incorporation of CeO2 nanoparticles (NPs), even though chloride anions in smaller amounts, and free water molecules, are simultaneously transferred at the film/electrolytic solution interface. This study also reveals that the kinetics of Cl- ion insertion occurring at the film/electrolyte interface upon oxidation is persistently slower in PPy-DS/CeO2 NPs films than in PPy-DS films throughout the entire potential window of investigation. However, the relative concentration changes of Cl- ions in PPy-DS/CeO2 NPs films is about two times greater than that occurring in pristine PPy-DS films. Such conclusion tends to demonstrate that CeO2 NPs have the ability to modify the morphology of electrodeposited PPy-DS thin films as well as their subsequent permeability towards ions contained in the electrolytic solution, possibly via the perturbation of polymer chain interactions and organisation.
Synthesis methods for Ce(CrO4)2 · xH 2O and crystal structures of K2CrSO7, (NH 4)2Cr2O7 and Na2Cr 2O7 · 2H2O
Casari, Barbara M.,Eriksson, Annika K.,Langer, Vratislav
, p. 771 - 777 (2007)
New and quick methods to synthesize Ce(CrO4)2 · 2H2O and Ce(CrO4)2 · H 2O, giving high yields, are described. The methods are based on exchange reactions by refluxing in water or on solid state reactions. The first crystal structure containing a chromatosulfato ion is presented. K 2CrSO7 belongs to space group P21/n with a = 7.4024(1), b = 7.3908(1), c = 12.9883(2) A?, β = 90.021(1)° and Z = 4. The CrSO72- ion, consisting of one chromate group sharing one oxygen atom with one sulfate group, has a pseudo syn-C2v conformation with eclipsed oxygen atoms. K2CrSO7 forms a three dimensional network of CrSO72- ions held together by the charge balancing potassium ions, with the general structural features common with dichromate-like structures. The redetermination of the structures of (NH4)2Cr2O7 (space group C2/c, with hydrogen atoms located) and Na2Cr2O7 · 2H2O (space group P21, with hydrogen atoms located and the absolute structure established) are reported.
Study of the Ru/Ce system in the oxidation of carbon black and volatile organic compounds
Aouad,Saab,Abi-Aad,Aboukais
, p. 835 - 840 (2007)
The relationship between the state of Ru on CeO2 and catalytic activity in the oxidation of carbon black (CB) and some volatile organic compounds (VOCs) was investigated for Ru/CeO2 catalysts prepared by wet impregnation. It was demo
Facile synthesis of ceria nanoparticles by precipitation route for UV blockers
Anupriya,Vivek,Subramanian
, p. 406 - 410 (2014)
Homogeneous ceria (CeO2) nano particles of approximately 4 nm have been successfully synthesized via a simple precipitation route by employing the mixed solvent method. X-ray diffraction analysis revealed the precipitate particles to be of highly crystalline nature with face centered cubic structure along (1 1 1) (2 0 0) (2 2 0) (3 1 1) (4 0 0) (3 3 1) (4 2 2) (5 1 1) planes. Cerium oxide nanoparticles exhibits enhanced specific surface area of about 139.116 m2/g. The mono-dispersed spherical shape morphology of approximately 4 nm particles was confirmed using TEM analysis and its chemical composition by SEM-EDS analysis. Surface morphology reveals the smooth surface with an average roughness of 14.9 nm with the help of AFM. Raman studies show a characteristic peak at 464 cm-1. The UV absorption edge was found at 314 nm i.e. In the Ultra Violet region suggesting that the material has a good absorption of UV light. Also, it shows an excellent transparency in the visible region.
Dipotassium tetrachromate(VI), K2Cr4O13
Casari, Barbara M.,Langer, Vratislav
, p. i117-i119 (2005)
The structure of dipotassium tetrachromium(VI) tridecaoxide, K 2Cr4O13, has been determined from single-crystal X-ray data collected at 173 (2) K on a racemically twinned crystal with monoclinic Pc space-group symmetry. The structure is composed of discrete [Cr4O13]2- zigzag chains held together by the charge-balancing potassium ions. The conformations adopted by the tetrachromate anion in alkali metal salts and Cr8O21 are different and can be divided into three categories.
Cerium doped magnetite nanoparticles for highly sensitive detection of metronidazole via chemiluminescence assay
Haddad Irani-nezhad, Mahsa,Hassandoost, Ramin,Joo, Sang Woo,Khataee, Alireza,Orooji, Yasin,Rahim Pouran, Shima
, (2020)
Cerium doped magnetite nanoparticle (CDM) was synthesized via a co-precipitation method and used as the co-reactant of luminol-K3Fe(CN)6 chemiluminescent system. The physical-chemical features of CDM were studied by XPS, XRD, HRTEM, FESEM, VSM, BET, and FTIR analyses. This simple and highly sensitive nanoprobe enabled the determination of minor concentrations of metronidazole (MNZ). Owing to the quenching efficacy of MNZ in the studied chemiluminescence system, a linear range of 3.47 × 10?6-9.37 × 10?5 mol/L was obtained with a limit of detection of 3.91 × 10?7 mol/L. This biosensor was used for MNZ detection in human serum samples, which was highly efficient. The outcomes of this study give credit to the proposed biosensor to be applied for detection of MNZ in biological samples.
New structure type among octahydrated rare-earth sulfates, β-Ce 2(SO4)3·8H2O, and a new Ce 2(SO4)3·4H2O polymorph
Casari, Barbara M.,Langer, Vratislav
, p. 1074 - 1081 (2007)
Syntheses, crystal structures and thermal behavior of two new hydrated cerium(III) sulfates are reported, Ce2(SO4) 3·4H2O (I) and β-Ce2(SO 4)3·8H2O (II), both forming three-dimensional networks. Compound I crystallizes in the space group P2 1/n. There are two non-equivalent cerium atoms in the structure of I, one nine-and one ten-fold coordinated to oxygen atoms. The cerium polyhedra are edge sharing, forming helically propagating chains, held together by sulfate groups. The structure is compact, all the sulfate groups are edge-sharing with cerium polyhedra and one third of the oxygen atoms, belonging to sulfate groups, are in the S-Oμ3-Ce2 bonding mode. Compound II constitutes a new structure type among the octahydrated rare-earth sulfates which belongs to the space group Pn. Each cerium atom is in contact with nine oxygen atoms, these belong to four water molecules, three corner sharing and one edge sharing sulfate groups. The crystal structure is built up by layers of [Ce(H2O)4(SO4)]nn+ held together by doubly edge sharing sulfate groups. The dehydration of II is a three step process, forming Ce2(SO4)3·5H 2O, Ce2(SO4)3·4H2O and Ce2(SO4)3, respectively. During the oxidative decomposition of the anhydrous form, Ce2(SO 4)3, into the final product CeO2, small amount of CeO(SO4) as an intermediate species was detected.
Thermochemical study of tetravalent metal sulfate tetrahydrates: A4+(SO4)2(H2O)4 (A4+?=?Zr, Ce, U)
Zhang, Lei,Lobeck, Haylie L.,Dzik, Ewa A.,Sigmon, Ginger E.,Burns, Peter C.
, p. 56 - 60 (2019)
The syntheses, characterization, and calorimetric measurements of enthalpies of formation of four tetravalent metal sulfate tetrahydrates (A4+(SO4)2(H2O)4 (A4+ = Zr, Ce, U): α-Zr(SO4)2(H2O)4, α-Ce(SO4)2(H2O)4, β-Ce(SO4)2(H2O)4, and β-U(SO4)2(H2O)4)are reported. Direct calorimetric measurements showed that the formation enthalpies of these compounds from the corresponding oxides correlate with the eightfold coordination radius of the tetravalent cations. An energetic slope change is observed between the α- (Fddd)and β- (Pnma)forms and is consistent with previously reported studies.
