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Clark et. al. 2003 USGS Open File Report 03-395
Spectral Library splib05a Sample Description

(For further information on spectrsocopy, see: http://speclab.cr.usgs.gov)

TITLE: Praseodymium_Oxide GDS35 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: GDS35

MINERAL_TYPE: Oxide

MINERAL: Praseodymium Oxide

FORMULA: PrO2

FORMULA_HTML: PrO2

COLLECTION_LOCALITY: REE Standard 81.6% Pr Lot No. 05791

ORIGINAL_DONOR: None

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.

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, EM(WDS), 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:

We have no reference spectra to evaluate the potential spectral interference from K3PrF6 or K2PrF5. We are tentatively assigning a spectral purity of "b" based on the assumed spectral purity of this reagent grade chemical sample. G. Swayze

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns

LIB_SPECTRA_HED: where Wave Range Av_Rs_Pwr Comment
LIB_SPECTRA: splib04a r 3946 0.2-3.0µm 200 g.s.= 5 µm
LIB_SPECTRA: splib05a r 5505 0.2-3.0µm 200 g.s.=


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