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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on CePO4 by Materials Project

CePO4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Ce3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ce–O bond distances ranging from 2.44–3.01 Å. P5+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.55 Å) and two longer (1.56 Å) P–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Ce3+ and one P5+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ce3+ and one P5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ce3+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to three equivalent Ce3+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CePO4 by Materials Project

CePO4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Ce3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ce–O bond distances ranging from 2.46–2.80 Å. P5+ is bonded in a tetrahedral geometry to four O2- atoms. There is three shorter (1.55 Å) and one longer (1.56 Å) P–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Ce3+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Ce3+ and one P5+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Ce3+ and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent Ce3+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CePO4 by Materials Project

CePO4 is Zircon-like structured and crystallizes in the hexagonal P6_422 space group. The structure is three-dimensional. Ce3+ is bonded to eight equivalent O2- atoms to form distorted CeO8 hexagonal bipyramids that share corners with four equivalent PO4 tetrahedra, edges with four equivalent CeO8 hexagonal bipyramids, and edges with two equivalent PO4 tetrahedra. There are four shorter (2.44 Å) and four longer (2.60 Å) Ce–O bond lengths. P5+ is bonded to four equivalent O2- atoms to form PO4 tetrahedra that share corners with four equivalent CeO8 hexagonal bipyramids and edges with two equivalent CeO8 hexagonal bipyramids. All P–O bond lengths are 1.55 Å. O2- is bonded in a 1-coordinate geometry to two equivalent Ce3+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CePO4 by Materials Project

CePO4 is Zircon-like structured and crystallizes in the hexagonal P6_222 space group. The structure is three-dimensional. Ce3+ is bonded to eight equivalent O2- atoms to form distorted CeO8 hexagonal bipyramids that share corners with four equivalent PO4 tetrahedra, edges with four equivalent CeO8 hexagonal bipyramids, and edges with two equivalent PO4 tetrahedra. There are four shorter (2.44 Å) and four longer (2.60 Å) Ce–O bond lengths. P5+ is bonded to four equivalent O2- atoms to form PO4 tetrahedra that share corners with four equivalent CeO8 hexagonal bipyramids and edges with two equivalent CeO8 hexagonal bipyramids. All P–O bond lengths are 1.55 Å. O2- is bonded in a 1-coordinate geometry to two equivalent Ce3+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CePO4 by Materials Project

CePO4 is Zircon structured and crystallizes in the tetragonal I4_1/amd space group. The structure is three-dimensional. Ce3+ is bonded in a 8-coordinate geometry to eight equivalent O2- atoms. There are four shorter (2.46 Å) and four longer (2.51 Å) Ce–O bond lengths. P5+ is bonded in a tetrahedral geometry to four equivalent O2- atoms. All P–O bond lengths are 1.56 Å. O2- is bonded in a 1-coordinate geometry to two equivalent Ce3+ and one P5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Impact of Primary and Secondary ZDDP and Ionic Liquid as Lubricant Oil Additives on the Performance and Physicochemical Properties of Pd-Based Three-Way Catalysts

In the present study, two industry primary and secondary zinc dialkyldithiophosphate standards, ZDDP1 and ZDDP2, respectively, are evaluated for their impact on the performance of Pd-based three-way catalyst and bench-marked against two mixed lubricant additives formed from either ZDDP1 or ZDDP2 with a second-generation oil-miscible phosphoric-containing ionic liquid (IL). The three-way catalysts (TWCs) are exposed to the lubricant additives in an engine bench under four different scenarios: a base case with no additive (NA), ZDDP1, IL+ZDDP1, ZDDP2, and IL+ZDDP2. The engine-aged TWC samples are characterized through a variety of analytical techniques, including evaluation of catalyst reactivity in a bench-flow reactor. With respect to the water–gas shift reaction and the oxygen storage capacity, the ZDDP2- and IL+ZDDP2-aged TWC samples are more degraded than the ZDDP1- and IL+ZDDP1-aged TWC samples. X-ray diffraction (XRD) patterns indicate that phosphorus in the form of CePO4 was found to be present in the washcoat of all TWC samples, with the highest amount found in the ZDDP2-aged TWC sample. The results obtained from XRD are further confirmed by those from inductively coupled plasma-optical emission spectroscopy (ICP-OES), which show that more phosphorus is detected in the washcoat of ZDDP2- and IL+ZDDP2-aged TWC samples than in the ZDDP1- and IL+ZDDP1-aged TWC samples.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

The solubility and speciation of REE phosphate endmembers (CePO 4 and YPO 4 ) in Cl-rich aqueous fluids from 350 to 450 °C and implications for natural systems

The rare earth elements (REE) are important metals used increasingly in advanced technologies. Within the crust, the elements Ce and Y are commonly more abundant compared to other lanthanides and comprise important end-member constituents of REE-bearing minerals. Specifically, Ce is part of the light (L) REE which have larger ionic radii than the heavy (H) REE, which are grouped together with Y. These differences in ionic radius can lead to important physico-chemical trends within the lanthanide group. Despite a recent increase in experimental and thermodynamic data for the REE at high temperature and pressure, there is still a significant lack of these data at supercritical conditions. In this study we conducted batch-type experiments to measure the solubility of REE phosphates (CePO 4 and YPO 4 ) at varying starting pH (1.5–10), and salinity (0.01–1.4 mol/kg NaCl) at 350 and P sat , and from 400 to 450 °C at 700 bar. Results show that the solubility of Ce (33–0.14 ppb) is generally higher than Y (13–0.13 ppb) and that Ce complexes more strongly with both chloride and hydroxyl ligands compared to Y. The solubilities of both REE phosphates are highly pH-dependent and, to a lesser extent, depend on salinity at the studied conditions. The solubility data from this study were implemented into the GEMSFITS program to optimize the thermodynamic properties of Ce and Y hydroxyl and chloride species. The updated standard partial molal Gibbs energies of formation (Δ f G 0 T,P ) are used within the experimental temperature and pressure range to accurately predict the CePO 4 and YPO 4 solubility and Ce and Y speciation behavior. Based on the updated thermodynamic properties we also provide formation constants (log β n Cl,OH ) for Ce and Y hydroxyl and chloride species. Updated thermodynamic properties are applied to model REE-apatite dissolution and REE mobility based on the Pea Ridge iron oxide apatite deposit in Missouri, USA. The apatite dissolution model replicates natural observations including the replacement of monazite and xenotime after apatite and is an example of the utility of the new thermodynamic constants applied to supercritical crustal fluids. Furthermore, the findings of this study advance the predictive capabilities of geochemical models, our understanding of the behavior of individual REE, and permit modeling the overarching fractionation trends between LREE and HREE in supercritical crustal fluids.

58 GEOSCIENCES↗