721880-19-9Relevant academic research and scientific papers
Hydrothermal growth and morphology evolution of CePO4 aggregates by a complexing method
Ma, Lin,Chen, Wei-Xiang,Zheng, Yi-Fan,Xu, Zhu-De
, p. 2840 - 2849 (2008)
A facile hydrothermal route assisted by Na2H2EDTA (ethylenediaminetetraacetic acid disodium) has been successfully developed to prepare uniform cerium phosphate (CePO4) aggregates with different morphologies, such as peanut-like and spindle-like. It was found that the as-prepared uniform CePO4 aggregates were constructed with many nearly parallel aligned nanorods. The molar ratio of EDTA/Ce3+, solution pH and reaction time had great influences on the morphologies and sizes of the CePO4 samples. In our process of synthesis, Na2H2EDTA played important roles as complexing reagent and inducing agent on the formation of CePO4 aggregates. The possible growth mechanism for CePO4 aggregates was presented. Ce0.9Tb0.1PO4 aggregates with different morphologies were also prepared and their photoluminescence properties were characterized.
Cerium phosphate nanotubes: Synthesis, valence state, and optical properties
Tang, Chengchun,Bando, Yoshio,Golberg, Dmitri,Ma, Renzhi
, p. 576 - 579 (2005)
A strong blue emission is observed for hybrid Ce3+/Ce 4+ cerium phosphate nanotubes, whereas Ce3+ phosphate nanowires exhibit a characteristic double-peak UV luminescence (see picture). These cerium phosphate systems were obtained by annealing novel cerium(IV) phosphate nanotubes at different temperatures.
The synthesis and thermal stability of CaKCe(PO4)2 phosphate. Phase equilibria in the CaKPO4-CePO4 system
Matraszek, Aleksandra,Szczygie?, Irena,Znamierowska, Teresa
, p. 138 - 144 (2013)
The compound CaKCe(PO4)2 was obtained using respectively the ceramic method, the Pechini method and the hydrothermal method. The low-temperature (Pechini and hydrothermal) methods yielded homogenous powders with a crystallite size up to 24 nm. The compound has a hexagonal structure with parameters of an elementary cell: a = b = 7.0468(8) ? and c = 6.4367(0) ?. The CaKCe(PO4)2 phosphate occurs in one polymorphic form. A phase equilibrium diagram of the CaKPO 4-CePO4 system has been established on the basis of XRD, DTA/DSC/TGA results. The initial phosphates were found to form one intermediate compound, CaKCe(PO4)2, with molar ratio CaKPO 4:CePO4 = 1:1, melting incongruently at a temperature of 1530 °C according to the reaction: CaKCe(PO4)2(cr) → CePO4(cr) + L. At a temperature of 1440 °C an eutectic was found to be present in the CaKPO4-CePO4 system at x(CePO4) = 0.25.
Synthesis and characterization of mixed-morphology CePO4 nanoparticles
Karpowich,Wilcke,Yu, Rong,Harley,Reimer,De Jonghe
, p. 840 - 846 (2007)
Cerium phosphate nanoparticles with diameters of 10-180 nm were synthesized by a variety of solution techniques. X-ray diffraction (XRD) determined the crystalline phase(s) present in each sample. Population, shift, and spin-lattice relaxation 31P solid-state nuclear magnetic resonance (NMR) measurements accounted for all the 31P nuclei expected in each sample, and were able to distinguish between phosphorous nuclei in different environments and phases. Transmission electron microscopy (TEM) characterized the morphology and crystallinity of the powder samples as well as of the sintered compacts of the powders. In conjunction with TEM, energy-dispersive spectroscopy (EDS) provided a measure of the composition of the bulk intergranular regions within each CePO4 sample. The presence of an amorphous, phosphate-rich intergranular phase was found in those samples prepared by dissolution of ceria in H3PO4 under various conditions.
Epitaxial synthesis of uniform cerium phosphate one-dimensional nanocable heterostructures with improved luminescence
Bu, Wenbo,Hua, Zile,Chen, Hangrong,Shi, Jianlin
, p. 14461 - 14464 (2005)
Uniform CePO4@LaPO4 and CePO4:Tb 3+@LaPO4 one-dimensional single-crystalline nanocable heterostructures with highly enhanced photoluminescent emission have been synthesized via a mild and simple hydrothermal approach. The resulting one-dimensional single-crystalline nanocable heterostructures have smooth and uniform LaPO4 sheaths, which is of great significance in effectively eliminating surface trap-states and suppressing the energy quenching in energy-transfer processes. The photoluminescence results for these one-dimensional nanocable heterostructures illustrate that the uniform LaPO 4 sheaths remarkably increase the luminescent efficiency. ? 2005 American Chemical Society.
Synthesis of cerium orthophosphates with monazite and rhabdophane structure from phosphoric acid solutions in the presence of hydrogen peroxide
Skogareva,Shekunova,Baranchikov,Yapryntsev,Sadovnikov,Ryumin,Minaeva,Ivanov
, (2016)
It has been proposed to conduct the synthesis of cerium(III) orthophosphates by reacting cerium(IV) compounds with hydrogen peroxide in the presence of concentrated orthophosphoric acid at ambient temperature. It has been shown that the reaction of H
Vapour phase O-alkylation of phenol over alkali promoted rare earth metal phosphates
Reddy,Sarala Devi,Giridhar
, p. 173 - 178 (2002)
The vapor phase synthesis of anisole by O-alkylation of phenol with methanol was studied over lanthanum, cerium, samarium, and antimony phosphate catalysts promoted with cesium hydroxide. The activity and selectivity trends on various catalysts followed the same pattern with temperature. The formation of some side products with traces of CO and CO2 were rarely noted at higher temperatures. The cesium promoted samarium phosphate showed maximum product yield (83%). The cesium promoter decreased the C-alkylation products and enhanced the O-alkylation product selectivity. The total amount of ammonia desorbed in the case of samarium was much higher than that of the Cs-Sm sample. A substantial decrease in the quantity of ammonia desorbed in the case of Cs-Sm catalyst indicated that the Cs promoter highly influenced the surface acidity of Sm-phosphate catalyst. Cs promoter had major influence on the strong acid sites of the catalyst.
Systematic Synthesis and Characterization of Single-Crystal Lanthanide Orthophosphate Nanowires
Fang, Yue-Ping,Xu, An-Wu,Song, Rui-Qi,Zhang, Hua-Xin,You, Li-Ping,Yu, Jimmy C.,Liu, Han-Qin
, p. 16025 - 16034 (2003)
A simple hydrothermal method has been developed for the systematic synthesis of lanthanide orthophosphate crystals with different crystalline phases and morphologies. It has been shown that pure LnPO4 compounds change structure with decreasing Ln ionic radius: i.e., the orthophosphates from Ho to Lu as well as Y exist only in the tetragonal zircon (xenotime) structure, while the orthophosphates from La to Dy exist in the hexagonal structure under hydrothermal treatment. The obtained hexagonal structured lanthanide orthophosphate LnPO4 (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, and Dy) products have a wirelike morphology. In contrast, tetragonal LnPO 4 (Ln = Ho, Er, Tm, Yb, Lu, Y) samples prepared under the same experimental conditions consist of nanoparticles. The obtained hexagonal LnPO4 (Ln = La → Tb) can convert to the monoclinic monazite structured products, and their morphologies remained the same after calcination at 900 °C in air (Hexagonal DyPO4 is an exceptional case, it transformed to tetragonal DyPO4 by calcination), while the tetragonal structure for (Ho→ Lu, Y)PO4 remains unchanged by calcination. The resulting LnPO4 (Ln = La → Dy) products consist almost entirely of nanowires/nanorods with diameters of 5-120 nm and lengths ranging from several hundreds of nanometers to several micrometers. Europium doped LaPO4 nanowires were also prepared, and their photoluminescent properties were reported. The optical absorption spectrum of CePO4 nanowires was measured and showed some differences from that of bulk CePO4 materials. The possible growth mechanism of lanthanide phosphate nanowires was explored in detail. X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, electron diffraction, infrared absorption spectra, X-ray photoelectron spectroscopy, optical absorption spectra, and photoluminescence spectra have been employed to characterize these materials.
Facile sonochemical synthesis and photoluminescent properties of lanthanide orthophosphate nanoparticles
Yu, Cuicui,Yu, Min,Li, Chunxia,Liu, Xiaoming,Yang, Jun,Yang, Piaoping,Lin, Jun
, p. 339 - 347 (2009)
Uniform lanthanide orthophosphate LnPO4 (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho) nanoparticles have been systematically synthesized via a facile, fast, efficient ultrasonic irradiation of inorganic salt aqueous solution under ambient conditi
Decomposition of chlorofluorocarbons over metal phosphate catalysis. II. Origin of the stability of AlPO4 and the location of CE as a promoter
Takita, Yusaku,Wakamatsu, Hironori,Li, Gong-Liang,Moro-Oka, Yoshihiko,Nishiguchi, Hiroyasu,Ishihara, Tatsumi
, p. 111 - 119 (2000)
Aluminum-phosphate catalysts prepared from aqueous solution of Al(NO3)36H2O and H3PO4 in acidic condition are effective for hydrolysis of CCl2F2. Active species of the AlPO4 catalysts were studied and it was found that not Al(PO3)3 but pure AlPO4 was active. AlPO4 was amorphous when calcined at 1000°C for 5 h. But a slight crystallization of AlPO4 took place after the reaction at 400°C for 1000 h. Crystallization of AlPO4 proceeded only in the presence of both CCl2F2 and water vapor. Replacement of 5-10 at.% of Al in AlPO4 by Ce increased the catalytic activity without changing the selectivity. The Ce-promoted catalysts were composed of the mixture of AlPO4 and CePO4. The compositions of the catalysts were the same as those of parent liquor in preparation and it was almost uniform in the surface and the bulk. AlPO4 in the Ce-promoted AlPO4 catalyst was partially crystallized after the calcination at 1000°C for 5 h. (C) 2000 Elsevier Science B.V.
