Monazite in Hydrothermal Veins from Alinci, Yugoslavia

Bermanec, Vladimir; Tibljaš, Darko; Gessner, M.; Kniewald, Goran

doi:10.1007/bf01164318

Cited by 12 publications

(5 citation statements)

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“…(B) Anhydrous Orthophosphates With a Monazite Structure: A number of reports 59–73 on mixed monazite‐type compounds are available in the literature, mostly due to the importance of these phases for nuclear waste management and for geological research. Table V lists these compounds with the corresponding references.…”

Section: Analysis and Discussionmentioning

confidence: 99%

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Solid Solubility and Thermal Expansion in a LaPO₄–YPO₄System

Mogilevsky

Boakye

Hay

2007

Journal of the American Ceramic Society

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The composition and lattice parameters of co-precipitated (La 0.3 Y 0.7 ) orthophosphate were studied using X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX). The results indicate that the as-precipitated powder consists of single-phase (La 0.3 Y 0.7-PO 4 . H 2 O) rhabdophane nanoparticles. Heat treatment at 9501C caused the decomposition of rhabdophane into a (La 1Àx Y x )PO 4 monazite solid solution and YPO 4 xenotime. The solid solubility of Y in LaPO 4 monazite from 10001 to 16001C was studied using XRD, TEM, and EDX. The implications of the findings for controlling the coefficient of thermal expansion of the prospective two-phase monazite-xenotime fiber coatings for ceramic composites applications are discussed. III. ResultsThe X-ray diffraction (XRD) pattern of the as-precipitated powder is shown in Fig. 1. The pattern is consistent with the hexagonal rhabdophane structure, similar to that of La rhabdophane, but with smaller lattice parameters (the pattern of La rhabdophane is included in Fig. 1 for comparison). The XRD peaks were indexed as shown in Fig. 1, and the lattice parameters were obtained by the least squares method. This resulted in lattice parameters of a 5 6.917 Å and c 5 6.366 Å , as compared with a 5 7.1 Å and c 5 6.494 Å for pure La rhabdophane. 23 EDX analysis yielded an average Y content in the powder of 69.8 at.% (with respect to the total cation content), in good agreement with the 7:3 Y to La molar ratio in which the components were mixed. 22 EDX elemental mapping of the as-precipitated powder revealed no phase separation or compositional inhomogeneity. 22 These results indicate that the as-precipitated particles are a solid solution of Y in hexagonal hydrous La orthophosphate (rhabdophane).

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Section: Analysis and Discussionmentioning

confidence: 99%

“… Lattice parameters of mixed monazite‐type compounds 59–73 relative to the corresponding cation radius in the rare‐earth site. Solid lines correspond to .…”

Section: Analysis and Discussionmentioning

confidence: 99%

Solid Solubility and Thermal Expansion in a LaPO₄–YPO₄System

Mogilevsky

Boakye

Hay

2007

Journal of the American Ceramic Society

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“…This is expected from the results of TG-DTA analysis, which showed that only dehydration occurred by calcination at 573 K. For the phosphate particles calcined at 1373 K, significant differences are shown in the XRD pattern, thus indicating that the crystalline structure is changed by the calcination, with the particles following calcination at 1373 K consisting of a Monazite (monoclinic) structure. 23 In the case of size and morphology, no significant change is apparent for calcination at 573 K compared to the particles without calcination. Following calcination at 1373 K, however, the particles were sintered and aggregated.…”

Section: Thermal Analyses Of the Particlesmentioning

confidence: 96%

The preparation of rare earth phosphate fine particles in an emulsion liquid membrane systemElectronic supplementary information (ESI) available: SEM images of phosphate particles prepared in the homogeneous system, and SEM images of La phosphate particles prepared via the ELM system, following calcination for 2 h at 573 and 1373 K. See http://www.rsc.org/suppdata/jm/b1/b105743j/

2002

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Phosphate particles of the selected rare earth metals have been prepared, using an emulsion liquid membrane [ELM, water-in-oil-in-water (W/O/W) emulsion] system, consisting of Span 83 (sorbitan sesquioleate) as surfactant and EHPNA (2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester) as extractant (cation carrier). The rare earth ions are extracted from the external water phase of the ELM system and are stripped into the internal water phase, containing phosphoric acid solution, to form the corresponding rare earth phosphate particles. The morphology and size of the particles are well-controlled by using the ELM system, and submicrometer-sized spherical phosphate particles are obtained, while micron-sized and irregular-shaped phosphate particles are obtained in homogeneous aqueous solutions. The resulting submicrometer-sized spherical particles were characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), and thermal analysis (TG-DTA). The characterization of La-based particles revealed that the fine particles obtained were of hexagonal structure, but their crystalline structure was changed to a monoclinic structure by calcination at 1373 K. Composite LaPO 4 :Ce 31 ,Tb 31 phosphor particles were then prepared by transporting La 31 , Ce 31 , and Tb 31 ions simultaneously, with the resulting particles showing good photoluminescence at 545 nm. In the ELM system, the size of the particles is able to be controlled in the range of 0.28 to 0.65 mm by changing the concentration of Span 83, whereas that in the homogeneous system is about 0.7 mm.

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“…It occurs typically as a small accessory phase in granitic and metamorphic rocks, but reaches larger sizes and higher modal abundancies in some carbonatites, pegmatites, alkaline rocks and metamorphic veins (e.g. Bermanec et al , 1988; Andreoli et al , 1994; Lehmann et al , 1994; Wall and Mariano, 1996; Gonçalves et al , 2016; Broom-Fendley et al , 2017; Montel et al , 2018; Ntiharirizwa et al , 2018; Slezak and Spandler, 2019). Monazite-(Ce) is of considerable importance for both practical and research reasons.…”

Section: Introductionmentioning

confidence: 99%

Sulfur-bearing monazite-(Ce) from the Eureka carbonatite, Namibia: oxidation state, substitution mechanism, and formation conditions

Broom-Fendley

Smith

Andrade

et al. 2019

MinMag

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Sulfur-bearing monazite-(Ce) occurs in silicified carbonatite at Eureka, Namibia, forming rims up to ~0.5 mm thick on earlier-formed monazite-(Ce) megacrysts. We present X-ray photoelectron spectroscopy data demonstrating that sulfur is accommodated predominantly in monazite-(Ce) as sulfate, via a clino-anhydrite-type coupled substitution mechanism. Minor sulfide and sulfite peaks in the X-ray photoelectron spectra, however, also indicate that more complex substitution mechanisms incorporating S2– and S4+ are possible. Incorporation of S6+ through clino-anhydrite-type substitution results in an excess of M2+ cations, which previous workers have suggested is accommodated by auxiliary substitution of OH– for O2–. However, Raman data show no indication of OH–, and instead we suggest charge imbalance is accommodated through F– substituting for O2–. The accommodation of S in the monazite-(Ce) results in considerable structural distortion that may account for relatively high contents of ions with radii beyond those normally found in monazite-(Ce), such as the heavy rare earth elements, Mo, Zr and V. In contrast to S-bearing monazite-(Ce) in other carbonatites, S-bearing monazite-(Ce) at Eureka formed via a dissolution–precipitation mechanism during prolonged weathering, with S derived from an aeolian source. While large S-bearing monazite-(Ce) grains are likely to be rare in the geological record, formation of secondary S-bearing monazite-(Ce) in these conditions may be a feasible mineral for dating palaeo-weathering horizons.

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Monazite in Hydrothermal Veins from Alinci, Yugoslavia

Cited by 12 publications

References 10 publications

Solid Solubility and Thermal Expansion in a LaPO₄–YPO₄System

Solid Solubility and Thermal Expansion in a LaPO₄–YPO₄System

Sulfur-bearing monazite-(Ce) from the Eureka carbonatite, Namibia: oxidation state, substitution mechanism, and formation conditions

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Monazite in Hydrothermal Veins from Alinci, Yugoslavia

Cited by 12 publications

References 10 publications

Solid Solubility and Thermal Expansion in a LaPO4–YPO4System

Solid Solubility and Thermal Expansion in a LaPO4–YPO4System

Sulfur-bearing monazite-(Ce) from the Eureka carbonatite, Namibia: oxidation state, substitution mechanism, and formation conditions

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Solid Solubility and Thermal Expansion in a LaPO₄–YPO₄System

Solid Solubility and Thermal Expansion in a LaPO₄–YPO₄System