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DOCUMENTATION_FORMAT: Man_Made
SAMPLE_ID: GDS35
MATERIAL_TYPE: Oxide
MATERIAL: Praseodymium (III and IV) Oxide
FORMULA: Pr2O3 & Pr2O4
FORMULA_HTML: Pr2O3 and Pr2O4
COLLECTION_LOCALITY: REE Standard 81.6% Pr Lot No. 05791
ORIGINAL_DONOR: Jim Crowley
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
SAMPLE_DESCRIPTION:
Spex standard 81.6% Pr Lot No. 05791
Reflectance spectra for reagent-grade Eu2O3, Nd2O3, Sm2O3, and Pr2O3 show the intense, narrow absorption bands caused by electronic transitions in trivalent rare earth elements (White, 1967; Dieke and Crosswhite, 1963). The absorption patterns produced by each of these oxides is distinctive for the particular rare earth element involved. The positions of the major bands for Nd2O3 and Sm2O3 are indicated in Table 2. Absorption features that occur near 1.4 and 1.9 µ cannot be unambiguously assigned to water or hydroxyl since some rare earth element oxides, notably Sm2O3 and Pr2O3, have electronic bands in these wavelength regions. The cause of the 2.35µ bands in two of the rare earth element oxide samples also has not been determined. Although White (1967) tentatively attributed similar features to water, the bands could be produced by minor amounts of CO3 or possibly by an undocumented REE-OH vibrational overtone. No carbonate or hydroxyl-bearing phases were detected by X-ray diffraction analysis of the rare earth element oxide samples.
Rowan, Lawrence C., Kingston, Marguerite J., Crowley, James K., Spectral Reflectance of Carbonatites and Related Alkalic Igneous Rocks: Selected Samples from Four North American Localities, Economic Geology, Vol 81, 1986, pp. 857-871.
IMAGE_OF_SAMPLE:
Sample is dark so is difficult to see in this photo.
END_SAMPLE_DESCRIPTION.
XRD_ANALYSIS:
40 kV - 30 mA, 6.5-9.5 keV
File: prox35,mdi (smear mount on quartz plate)
References: JCPDS #24-1006, 22-0848, 40-08240, 45-11740
Found: PrO2 Cubic; Eight unindexed reflections at 3.23, 2.80. 2.24, 2.11, 1.87,
1.84, 1.83 and 1.44 Angstroms.
Comment: The dominant phase has strong narrow peaks but poor resolution of alpha1-alpha2.
The cell face-centered cubic with a=5.39 Angstroms; peak positions and intensities
match those in JCPDS #24-1006. The unindexed reflections are moderately weak
to weak, broad, poorly formed, and do not resolve alpha1-alpha2. Simple boolean
search of the PDF database using Pr composition and the two strongest unindexed
reflections (at 3.23 and 2.24 Angstroms) suggests that K3PrF6 and K2PrF5 (which
have peaks that overlap those of cubic PrO2) may be contaminants.
END_XRD_ANALYSIS.
COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, ICP(Trace), WChem
COMPOSITION_TRACE:
COMPOSITION_DISCUSSION:
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
No observed Impurities. G. Swayze.
average grain size= 5 µm
END_MICROSCOPIC_EXAMINATION.
SPECTROSCOPIC_DISCUSSION:
This spectrum has a strong dropoff into the visible region that may be due to a charge transfer band caused by the presence of minor Pr4+ caused by oxidation of the sample over time. This broad strong band swamps several f-f transition absorptions that would normally be present if this were a sample of pure Pr3+. See spectra of the other Praseodymium compounds for examples of those other f-f transition absorptions. G. Swayze. We have no reference spectra to evaluate the potential spectral interference from K3PrF6 or K2PrF5. We are tentatively assigning a spectral purity of "c" and "b" based on the assumed spectral purity of this reagent grade chemical sample. G. Swayze
END_SPECTROSCOPIC_DISCUSSION.
SPECTRAL_PURITY: 1c2b3b4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns