Clark and others 2007 USGS Data Series 231
Spectral Library splib06a Sample Description

(For further information on spectroscopy, 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.

IMAGE_OF_SAMPLE:

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: 1b2b3b4_ # 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.=
LIB_SPECTRA:	splib06a r 18039			g.s.=
LIB_SPECTRA:	splib06a r 18051			g.s.=