Rare earth phosphate powders RePO4·nH2O (Re=La, Ce or Y) II. Thermal behavior

Lucas, S.; Champion, Éric; Bernache‐Assollant, Didier; Leroy, G.

doi:10.1016/j.jssc.2003.11.004

Cited by 142 publications

(108 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…By calcination, this compound was decomposed to CePO4 and CeP2O7 with water evaporation [20]. The X-ray results are in agreement with the results obtained by Masui et al [21], where they observed that the preparation of CePO4 gives an amorphous state up to 723 K and above this temperature other phases were observed as CePO4 and CeP2O7 where CeP2O7 is converted to CePO4 by calcination above 1173 K. It may be concluded that the produced phases of CePO4 are greatly dependant on the methods of preparation and the precursor materials (the phosphates species in the medium) as reported from the previous work [22][23][24] who used Ce(SO4).4H2O for preparation. It seems that, the resulting CePO4 is trivalent cations while it was added in the tetravalent state, this may be due to the reduction of Ce 4+ to Ce 3+ in the acidic medium.…”

Section: Resultssupporting

confidence: 92%

Synthesis and microstructure studies of nano-sized cerium phosphates

et al. 2010

View full text Add to dashboard Cite

KEYWORDSCerium phosphate, CePO4, nanoparticles with hexagonal or monoclinic phase was synthesized by the reaction between Ce(SO4)2.4H2O and two different phosphate sources, H3PO4 and Na2HPO4. The obtained gel was dried and calcined at different temperatures (200, 400, and 800 о C). The effects of the precursor materials and the calcination temperatures on the produced phases were studied. Both X-ray diffraction (XRD) and infrared spectroscopy (IR) were used to follow the changes in the phase structure for the produced samples. The thermal behaviour of the as prepared samples was studied by using differential scanning calorimetric (DSC) and thermogravimetric analysis (TGA). The morphology, crystallinity and particle size of the produced samples as prepared and calcinated were characterized by transmission electron microscope (TEM). The analysis of TEM results indicated that CePO4 was prepared in nano-sized particles.Cerium phosphate Synthesis X-ray diffraction IR DSC/TGA TEM

show abstract

Section: Resultssupporting

confidence: 92%

Synthesis and microstructure studies of nano-sized cerium phosphates

et al. 2010

View full text Add to dashboard Cite

show abstract

“…The present study focused on the thermal stability of the unidentified structures, MREPO 4,hyd and HREPO 4,hyd , which were stable in air up to 100-300 • C on the time-scale of the experiments. The thermal stability of these two types of phosphates was comparable to the stability of YPO 4 ·2H 2 O, in which the churchite structure transforms to the xenotime structure by annealing at~100 • C for 73 h and at~200 • C within 1 h [50,51]. Non-coordinated water seems to be unrelated to the crystal structure, based on a comparison between the TG-DTA charts and the XRD patterns of heated samples (Figures 4 and 6).…”

Section: Properties Of Repo 4hyd Formed At Room Temperaturementioning

confidence: 95%

“…In the present study, the structures of REPO 4,hyd were classified into three categories: LREPO 4,hyd corresponds to the rhabdophane structure, whereas the structures of both MREPO 4,hyd and HREPO 4,hyd could not be conclusively identified. The thermal stability of rhabdophane has been thoroughly investigated in previous studies and the rhabdophane structure is known to be stable up to~500 • C-800 • C [15,48,49],~750 • C [50]. The present study focused on the thermal stability of the unidentified structures, MREPO 4,hyd and HREPO 4,hyd , which were stable in air up to 100-300 • C on the time-scale of the experiments.…”

Section: Properties Of Repo 4hyd Formed At Room Temperaturementioning

confidence: 97%

Crystal Chemistry and Stability of Hydrated Rare-Earth Phosphates Formed at Room Temperature

Ochiai

Utsunomiya

2017

Minerals

View full text Add to dashboard Cite

Abstract:In order to understand the crystal chemical properties of hydrous rare-earth (RE) phosphates, REPO 4,hyd , that form at ambient temperature, we have synthesized REPO 4,hyd through the interaction of aqueous RE elements (REEs) with aqueous P at room temperature at pH < 6, where the precipitation of RE hydroxides does not occur, and performed rigorous solid characterization. The second experiment was designed identically except for using hydroxyapatite (HAP) crystals as the P source at pH constrained by the dissolved P. Hydrated RE phosphate that precipitated at pH 3 after 3 days was classified into three groups: LREPO 4,hyd (La → Gd) containing each REE from La-Gd, MREPO 4,hyd (Tb → Ho), and HREPO 4,hyd (Er → Lu). The latter two groups included increasing fractions of an amorphous component with increasing ionic radius, which was associated with non-coordinated water. RE all PO 4,hyd that contains all lanthanides except Pm transformed to rhabdophane structure over 30 days of aging. In the experiments using HAP, light REEs were preferentially distributed into nano-crystals, which can potentially constrain initial RE distributions in aqueous phase. Consequently, the mineralogical properties of hydrous RE phosphates forming at ambient temperature depend on the aging, the pH of the solution, and the average ionic radii of REE, similarly to the well-crystalline RE phosphates.

show abstract

“…Of late, synthesis of nanocrystalline rare earth phosphates has been attempted via various methods, such as the sol-gel method, the surfactant-directed hydrothermal approach, etc. [11,12]. Cerium phosphate is an important class of rare earth phosphate ceramic, which has immense use in high temperature applications due to its high melting point.…”

Section: Introductionmentioning

confidence: 99%