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(Optical characterization techniques applied to ceramic oxides)

Description: The traveler collaborated with M.J.M. Leask, J.M. Baker, B. Bleaney, and others at the Clarendon Laboratory, Oxford University, Oxford, UK, to Study Tetragonal rare-earth phosphates and vanadates by optical and magnetic spectroscopy. This work is related to similar studies that have been performed at ORNL by the Synthesis and Properties of Novel Materials Group in the Solid State Division.
Date: October 15, 1990
Creator: Abraham, M.M.
Partner: UNT Libraries Government Documents Department

Energy conservation opportunities in small commercial buildings

Description: As part of a joint project between Duke Power Co. and Oak Ridge National Laboratory (ORNL), a study was performed to determine the energy savings potential of small commercial buildings, located in the Duke Power service territory. This relatively untouched portion of the commercial sector has the potential for reducing energy consumption by 13% - 25%, which corresponds to a reduction in average annual operating costs of $500 - $1000 per building. A database of over sixty customers was used to target five buildings with unusually high levels of energy consumption and/or peak demand. Conservation measures in these buildings were selected on the basis of cost-effectiveness and relative non-intrusiveness on the occupants. Together, ORNL and Duke Power representatives worked on data analysis, site-audits, and measure recommendations. Duke Power supplied hourly and monthly utility data, customer survey information and participated in site-audits. ORNL analyzed the data, developed targeting indices, performed site-audits and corresponding first-order energy simulations on candidate buildings, and recommended individualized conservation retrofits. For the five buildings examined, retrofits including lighting, controls, and HVAC systems accounted for a total reduction in consumption of 32%, and in peak demand of 22%. In addition, the study emphasizes the importance of continuous attention to the operating conditions of HVAC equipment and controls, in order to ensure long-term sustainability of these energy savings.
Date: August 1, 1995
Creator: Abraham, M.M. & MacDonald, J.M.
Partner: UNT Libraries Government Documents Department

The evaluation of retrofit measures in a tall residential building

Description: As part of a joint demonstration effort involving the US Department of Energy (DOE), the US Department of Housing and Urban Development (HUD), Boston Edison Company (BECo), and the Chelsea Housing Authority, Oak Ridge National Laboratory (ORNL) participated in the evaluation of energy and demand saving retrofits for a tall residential building located in Boston. The thirteen story all-electric building underwent window, lighting, and control renovations in December, 1992. annual energy consumption was reduced by 15% and peak demand fell by 17%. Hourly should building consumption data were available for the comparison of pre- and post- conditions and for calibration of a DOE-2.1D simulation model. The analysis found the window retrofit accounted for 90% of total energy savings and 95% of average demand savings, due to reductions in both conduction and infiltration. Benefits from lighting retrofits were low in cooling months and negligible in winter months due to the increase in the demand for electric resistance heating which was proportional to the reduction in lighting capacity. Finally, the simulation model verified that heating system controls had not been used as intended, and that the utility rate structure would not allow cost savings from the original control strategy. These results and other interesting lessons learned are presented.
Date: July 1, 1995
Creator: Abraham, M.M. & McLain, H.A.
Partner: UNT Libraries Government Documents Department

Characterization of nuclear waste forms by EPR spectroscopy

Description: Single crystals of LaPO/sub 4/ have been grown with the addition of various amounts of PW-4b simulated waste, and the EPR spectra of Gd/sup 3 +/ in these samples have been compared with that obtained for a pure LaPO/sub 4/ single crystal. The relationship between the average linewidth of two symmetric EPR transitions and their magnetic field separation for pure and PW-4b doped LaPO/sub 4/ crystals are shown quantitatively. These measurements were carried out for four different crystals and two different magnetic field orientations. Since the linewidth of each transition is proportional to its magnetic field separation from the central line, it can be concluded that the line broadening is inhomogeneous (i.e., the line broadening is due to a distribution of line positions with this distribution resulting from a distribution of impurities in the crystal). The sensitivity of Gd/sup 3 +/ linewidths to defects or strains is also under investigation as a means of detecting metamictization phenomena in orthophosphates. Mixed Ln/sub 1-x/An/sub x/PO/sub 4/ crystals, where Ln is a rare earth and An an actinide, have been grown and EPR spectra of Gd/sup 3 +/ in these systems are of considerable interest for detecting radiation damage created by ..cap alpha..-particles or recoil of the daughter nuclei. Although the examples of the application of EPR to waste form characterization described here have emphasized studies of lanthanide orthophosphates, the same techniques can be applied to perovskite, hollandite, zirconolite, etc. single crystals or powders or to amorphous materials.
Date: October 1, 1980
Creator: Boatner, L.A.; Abraham, M.M. & Rappaz, M.
Partner: UNT Libraries Government Documents Department

EPR investigations of impurities in the lanthanide orthophosphates

Description: Lanthanide orthophosphates formed from elements in the first half of the 4f transition series are analogs of the monoclinic mineral monazite. The known geologic properties of this mineral make the general class of lanthanide orthophosphate compounds attractive substances for long-term containment and disposal of ..cap alpha..-active actinide nuclear wastes. EPR spectroscopy has been used to investigate the structural properties and solid state chemical properties of impurities in these materials and to compare the characteristics of single crystals and polycrystalline bodies.
Date: September 1, 1980
Creator: Abraham, M.M.; Boatner, L.A. & Rappaz, M.
Partner: UNT Libraries Government Documents Department

Lanthanide orthophosphates as a matrix for solidified radioactive defense and reactor wastes

Description: Lanthanum phosphate is a promising host material for reprocessed light water reactor wastes (e.g., PW-4b). This is demonstrated by the high density of the composite waste form and by the low leach rates of both Cs and Sr. Additionally, crystallographic data on LaPO/sub 4/ pellets loaded with 10 wt % simulated PW-4b indicate the presence of only one phase, i.e., monoclinic monazite. The rare-earth orthophosphates have also been shown to be a viable waste form for Savannah River (SRW) defense wastes. Compaction and sintering studies indicate that the rare-earth phosphate mixture employed here is preferable to pure LaPO/sub 4/ for containing SRW. Higher density and more homogeneous samples were obtained by using the mixed phosphates as compared to pure LaPO/sub 4/ as the host material. It is shown that aluminum removal from the composite SRW is not necessary when incorporating this type of waste into a rare-earth phosphate host. The current results support the view that lanthanide orthophosphate waste forms (i.e., monazite) are potentially superior to borosilicate glasses in the following respects: (1) lower processing temperatures (approx. 1000/sup 0/C versus 1160/sup 0/C for glass); (2) significantly higher waste per volume loadings for a given wt % of waste for monazites relative to glass; and (3) the current leaching data show that monazite-type waste forms are clearly superior to glass in retaining Sr, and, in particular, Cs.
Date: January 1, 1981
Creator: Petek, M.; Abraham, M.M. & Boatner, L.A.
Partner: UNT Libraries Government Documents Department

Production of point defects in 14.8 MeV neutron-irradiated MgO

Description: High-purity MgO crystals grown at ORNL were irradiated in the LLL 14.8- MeV Rotating Target Neutron Source (RTNS) to doses varying from 1.8 x 10$sup 15$ to 5.7 x 10$sup 17$ n/cm$sup 2$. The optical absorption spectra of these crystals resembled those irradiated in fission reactors and exhibited bands principally at 4.95, 3.5, 2.2, and 1.3 eV. The band with the largest absorption coefficient, that at 4.95 eV, is due to anion vacancies. The bands at 3.5 and 1.3 eV, attended by zero-phonon lines at 3.430 and 1.187 eV respectively, are attributed to different optical transitions of anion divacancies. The investigations indicate that the net production rates of the point defects resulting from irradiations with 14.8-MeV neutrons are about twice those resulting from fission neutrons in the Oak Ridge Reactor (ORR). This ratio is in reasonable accord with theoretical estimates based on damage energy calculations. (auth)
Date: September 1, 1975
Creator: Chen, Y.; Abraham, M.M.; Robinson, M.T.; Mitchell, J.B. & Van Konynenburg, R.A.
Partner: UNT Libraries Government Documents Department

Impact evaluation of the energy retrofits installed in the Margolis high-rise apartment building, Chelsea housing authority

Description: As part of a joint demonstration effort involving HUD, DOE, a local public housing authority and Boston Edison, an evaluation of energy and demand saving retrofits was conducted for a tall, residential, low-income building located in Boston. The thirteen story building underwent window, lighting, and heating system control renovations in December, 1992. The success of these retrofits was determined using monthly and hourly whole-building consumption data along with a calibrated DOE-2.1D energy simulation model. According to the model developed, post-retrofit conditions showed reductions in annual energy consumption of 325 MWh and in peak demand of 100 kW. These savings resulted in an annual energy cost savings of $28,000. Over 90% of energy and cost savings were attributed to the window retrofit. Interaction of the reduction in lighting capacity with the building`s electric resistance heating system reduced the potential for energy and demand savings associated with the lighting retrofit. Results from the hourly simulation model also indicate that night setbacks controlled by the energy management system were not implemented. An additional 32 MWh in energy savings could be obtained by bringing this system on-line, however peak demand would be increased by 40 kW as the morning demand for space heat is increased, with a net loss in cost savings of $2,500.
Date: March 1, 1995
Creator: Abraham, M.M.; McLain, H.A. & MacDonald, J.M.
Partner: UNT Libraries Government Documents Department

Effects of self-radiation damage on electronic properties of {sup 244}Cm{sup 3+} in an orthophosphate crystal of YPO{sub 4}

Description: Electronic energy level of alpha-emitting isotope {sup 244}Cm{sup 3+} (t{sub {1/2}}=18.1 y) doped into single crystals of YPO{sub 4} has been studied using site-selected laser spectroscopic methods. Electronic transitions between the nominal {sup 8}S{sub 7/2} state of Cm{sup 3+} were utilized to characterize the effects of alpha-decay induced structural damage. The total splitting of the four crystal field doublets in the ground multiplet is 12.5 cm{sup -1} and that of the excited multiplet is 611 cm{sup -1}. Due to radiation damage accumulated in 17 years since the crystals were grown, the inhomogeneous line width of the {sup 8}S{sub 7/2} {leftrightarrow} {sup 6}D{sub 7/2} transitions in broader than 50 cm{sup -1} as measured without site selection. The line width of resonant fluorescence line narrowing (RFLN) is less than 1 cm{sup -1} at 4 K. A total of 12 satellite lines were observed symmetrically spacing about the RFLN line. The position, width, and intensity of these satellite lines have been analyzed to gain information on the electronic and structural properties of the actinide ions in the metamict phases of Cm{sup 3+}:YPO{sub 4}.
Date: October 1, 1997
Creator: Liu, G.K.; Li, S.T.; Beitz, J.V. & Abraham, M.M.
Partner: UNT Libraries Government Documents Department

Characterization of the rare earth orthophosphates and Ce-doped LaPO{sub 4} by X-ray Absorption Spectroscopy

Description: X-ray Absorption Spectroscopy (XAS) of the Rare Earth (RE) 3d levels yields sharp peaks near the edges as a result of strong, quasi-atomic 3d{sup 10}4f {yields} 3d{sup 9}4f{sup n+1} (M{sub 4,5}) transitions that contain a wealth of spectroscopic features. XAS is a useful technique for the characterization of 4f-occupancy, 4f-hybridization, and valence in RE-containing materials. The XAS measurements of the single crystal RE-orthophosphates, as well as a range of Cedoped ({approx}1--30%) LaPO{sub 4} hosts were performed at the 3d edge in the total electron yield mode at beamline 8-2 at the Stanford Synchrotron Radiation Laboratory (SSRL). The XAS spectra of the RE ions in the orthophosphate matrix generally resemble that of the corresponding RE metal and emphasize the major contribution of the trivalent state to the electronic transitions occurring at the 3d edge. There is no energy shift of the La and Ce absorption peaks with Ce doping and furthermore, no additional transitions are observed in either spectral region. However, accompanying the Ce doping there is a significant narrowing of the La absorption peak full width half maximum that contrasts to the Ce features that exhibit no contraction. The La and Ce spectra indicate that the Ce-doping of LaPO{sub 4} is purely substitutional.
Date: December 31, 1993
Creator: Shuh, D. K.; Perry, D.; Terminello, L. J.; Boatner, L. A. & Abraham, M. M.
Partner: UNT Libraries Government Documents Department

Neutron study of crystal-field transitions in ErPO{sub 4}

Description: The crystal-field splitting of the Er{sup 3+} ground multiplet, {sup 4}I{sub 15/2}, in ErPO{sub 4} is investigated by inelastic neutron scattering. Four excitations from the {Gamma}{sub 7} ground state to the excited states and several transitions between the excited states have been identified. The observed transition energies and intensities are used to refine the parameters of the crystal-field potential. The calculated magnetic susceptibility, {chi}(T), agrees well with experimental values from single-crystal measurements. A comparison of the neutron data with optical absorption and both nonresonance and resonance Raman scattering measurements has been made.
Date: December 1, 1992
Creator: Loong, C.-K.; Soderholm, L.; Hammonds, J. P.; Abraham, M. M.; Boatner, L. A. & Edelstein, N. M.
Partner: UNT Libraries Government Documents Department

Neutron study of crystal-field transitions in ErPO[sub 4]

Description: The crystal-field splitting of the Er[sup 3+] ground multiplet, [sup 4]I[sub 15/2], in ErPO[sub 4] is investigated by inelastic neutron scattering. Four excitations from the [Gamma][sub 7] ground state to the excited states and several transitions between the excited states have been identified. The observed transition energies and intensities are used to refine the parameters of the crystal-field potential. The calculated magnetic susceptibility, [chi](T), agrees well with experimental values from single-crystal measurements. A comparison of the neutron data with optical absorption and both nonresonance and resonance Raman scattering measurements has been made.
Date: January 1, 1992
Creator: Loong, C.-K.; Soderholm, L.; Hammonds, J.P. (Argonne National Lab., IL (United States)); Abraham, M.M.; Boatner, L.A. (Oak Ridge National Lab., TN (United States)) & Edelstein, N.M. (Lawrence Berkeley Lab., CA (United States))
Partner: UNT Libraries Government Documents Department