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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Optical constants, single-oscillator modal and refractive index dispersion analysis of lithium zinc bismuth borate glasses doped with Eu{sup 3+} ions

The glasses of composition xLi{sub 2}O-15ZnO- 20Bi{sub 2}O{sub 3}- (64 - x) B{sub 2}O{sub 3}- 1EuO (ZLB) (where x=0, 5, 10, 15, 20 mole %) prepared by melt-quenching technique. The amorphous nature of the prepared glasses was confirmed by XRD spectra. The UV-Vis optical absorption spectrum was recorded in the wave length range of 200-1000 nm. It is observed that the optical band gap is inversely changing with Urbach energy. The optical constants such as G (a constant proportional to the second-order deformation potential) and E{sub f} (a constant that depends on local coordination and is called as free energy of the glass system). The most significant result of the present work is the refractive index dispersion curves of the ZLB glasses obey the single-oscillator model and oscillator parameters (E{sub o}, E{sub d}) changed with the Li{sub 2}O content. the absorption edge, band gap and Urbach energy is changing nonlinearly with increasing content of Li{sub 2}O, which can be used to calculate the optical, physical, and other constants.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Composition dependent spectroscopic properties of Nd{sup 3+} doped sodium lead borate glasses

Nd{sup 3+} doped oxide glasses of the type xNa{sub 2}O–30 PbO–(69.5-x) B{sub 2}O{sub 3}–0.5Nd{sub 2}O{sub 3} were prepared and investigated for physical and spectroscopic properties. Optical absorption spectra and Judd-Ofelt theory has been used to determine the oscillator strengths and the intensity parameters Ω{sub λ} (λ=2, 4, 6). The radiative transition probability (A), radiative lifetime (τ{sub R}) and branching ratio (β{sub R}) for the fluorescent levels of Nd{sup 3+} in the prepared glasses have been determined. The lasing efficiency of the prepared glasses has been characterized by the spectroscopic quality factor (Ω{sub 4} / Ω{sub 6}), the value of which is in the range 0.2-1.5, typical for Nd{sup 3+} in different laser hosts. The radiative transition probability of the potential lasing transition {sup 4}F{sub 3/2} → {sup 4}I{sub 11/2} of Nd{sup 3+} ions is found to increase with increase in content of Na{sub 2}O.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Dielectric properties of nickel doped bismuth lithium borate glasses

Glasses with composition xBi{sub 2}O{sub 3}•(30-x)Li{sub 2}O•70B{sub 2}O{sub 3} (x = 0, 2, 5, 7 and 10 mol% with codes BLBN1-5 respectively) containing 2 mol% of NiO were prepared via melt-quenching technique and dielectric properties are discussed. The dielectric properties have been studied using impedance spectroscopy. The frequency dependent conductivity investigations for prepared compositions have been carried out using impedance spectroscopy over a frequency range of 1 KHz to 5 MHz and in the temperature range of 300 K-523 K. The complex impedance data have been analyzed by using both the conductivity and the electric modulus formalisms. Standard dielectric behavior is observed in prepared samples. The ac conductivity variations satisfy the Arrhenius relation. The study of the equivalent circuit analysis up to a temperature of 473 K shows a significant change in the equivalent circuit with change in temperature and composition.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2011

Broadband colored-crescent generation in a single {beta}-barium-borate crystal by intense femtosecond pulses

A visible colored crescent with a bandwidth broader than 220 nm is observed experimentally by loosely focused femtosecond pulses in a bulk quadratic nonlinear crystal ({beta}-BBO crystal) at certain incident angles. Through the analysis based on a simple collinear phase-matching model, we suggest that the colored crescent might be the coexistence of spontaneous parametric down-conversions (SPDCs) in the infrared range and the corresponding efficient second-order harmonic generations (SHGs) that occur in a wide spectrum. We further provide a possible mechanism for the SHG process in which the phase-mismatching angles of the frequency doubling of SPDCs in {beta}-BBO crystal are assumed to be compensated by the strong diffraction effect during the self-focusing process of the generated intense SPDC signals.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Performance of Large Neutron Detectors Containing Lithium-Gadolinium-Borate Scintillator

This paper describes the development and testing of a neutron counter, spectrometer, and dosimeter that is compact, efficient, and accurate. A self-contained neutron detection instrument has wide applications in health physics, scientific research, and programs to detect, monitor, and control strategic nuclear materials (SNM). The 1.3 liter detector head for this instrument is a composite detector with an organic scintillator containing uniformly distributed {sup 6}Li{sub 6}{sup nat}Gd{sup 10}B{sub 3}O{sub 9}:Ce (LGB:Ce) microcrystals. The plastic scintillator acts to slow impinging neutrons and emits light proportional to the energy lost by the neutrons as they moderate in the detector body. Moderating neutrons that have slowed sufficiently capture in one of the Lithium-6, Boron-10, or Gadolinium-157 atoms in the LGB:Ce scintillator, which then releases the capture energy in a characteristic cerium emission pulse. The measured captured pulses indicate the presence of neutrons. When a scintillating fluor is present in the plastic, the light pulse resulting from the neutron moderating in the plastic is paired with the LGB:Ce capture pulse to identify the energy of the neutron. About 2% of the impinging neutrons lose all of their energy in a single collision with the detector. There is a linear relationship between the pulse areas of this group of neutrons and energy. The other 98% of neutrons have a wide range of collision histories within the detector body. When these neutrons are 'binned' into energy groups, each group contains a distribution of pulse areas. This data was used to assist in the unfolding of the neutron spectra. The unfolded spectra were then validated with known spectra, at both neutron emitting isotopes and fission/accelerator facilities. Having validated spectra, the dose equivalent and dose rate are determined by applying standard, regulatory damage coefficients to the measured neutron counts for each energy bin of the spectra. Testing at the Los Alamos Neutron Science Center (LANSCE), Edwards Accelerator Laboratory (EAL) at Ohio University and the Radiation Center at University of Massachusetts-Lowell has demonstrated that the instrument can measure neutrons and their spectra over the range between 0.8 MeV and 150 MeV with an uncertainty of only ± 8%. An independent test of the LGB:Ce neutron spectrometer was conducted by a US Defense Threat Reduction Agency (DTRA) team at the Idaho National Laboratory (INL). The results of this evaluation showed that the neutron spectrometer accurately identified bare radioactive isotopes by their spectra. Further, masking and shielding materials alter those spectra in predictable ways that permit an extrapolation from the observed spectra back to the identity of the isotopic spectrum. (authors)

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

A Single‐Ion Conducting Borate Network Polymer as a Viable Quasi‐Solid Electrolyte for Lithium Metal Batteries

Abstract Lithium‐ion batteries have remained a state‐of‐the‐art electrochemical energy storage technology for decades now, but their energy densities are limited by electrode materials and conventional liquid electrolytes can pose significant safety concerns. Lithium metal batteries featuring Li metal anodes, solid polymer electrolytes, and high‐voltage cathodes represent promising candidates for next‐generation devices exhibiting improved power and safety, but such solid polymer electrolytes generally do not exhibit the required excellent electrochemical properties and thermal stability in tandem. Here, an interpenetrating network polymer with weakly coordinating anion nodes that functions as a high‐performing single‐ion conducting electrolyte in the presence of minimal plasticizer, with a wide electrochemical stability window, a high room‐temperature conductivity of 1.5 × 10 −4 S cm −1 , and exceptional selectivity for Li‐ion conduction ( t Li+ = 0.95) is reported. Importantly, this material is also flame retardant and highly stable in contact with lithium metal. Significantly, a lithium metal battery prototype containing this quasi‐solid electrolyte is shown to outperform a conventional battery featuring a polymer electrolyte.

Shin, Dong‐Myeong↗
DOE OSTI2015

Morphology and orientation of β-BaB{sub 2}O{sub 4} crystals patterned by laser in the inside of samarium barium borate glass

Nonlinear optical β-BaB{sub 2}O{sub 4} crystal lines (β-BBO) were patterned in the inside of 8Sm{sub 2}O{sub 3}–42BaO–50B{sub 2}O{sub 3} glass by irradiations of continuous-wave Yb:YVO{sub 4} lasers with a wavelength of 1080 nm (power: P=0.8–1.0 W, scanning speed: S=0.2–2.5 μm/s), in which the laser focal position was moved gradually from the surface to the inside. The morphology, size, and orientation of β-BBO crystals were examined from polarization optical microscope and birefringence imaging observations. It was demonstrated that c-axis oriented β-BBO crystals with long lengths (e.g., 20 mm) were patterned in the inside of the glass. The morphology of β-BBO in the cross-section of lines was a rectangular shape with rounded corners, and the volume of β-BBO formed increased with increasing laser power and with decreasing laser scanning speed. The maximum depth in the inside from the surface for β-BBO patterning increased with increasing laser power, e.g., D{sub max}∼100 μm at P=0.8 W, D{sub max}∼170 μm at P=0.9 W, and D{sub max}∼200 μm at P=1 W. The present study proposes that the laser-induced crystallization opens a new door for applied engineering in glassy solids. - Graphical abstract: This figure shows the POM photographs for β-BaB{sub 2}O{sub 4} crystal lines patterned by cw Yb:YVO{sub 4} fiber laser irradiations with a laser power of P=0.8 W and a laser scanning speed S=2 μm/s in the glass. The laser focal point was moved gradually from the surface into the inside. The results shown in Fig. 1 demonstrate that it is possible to pattern highly oriented β-BaB{sub 2}O{sub 4} crystals even in the inside of glasses. - Highlights: • β-BaB{sub 2}O{sub 4} crystal lines were patterned in the inside of a glass by lasers. • Laser focal position was moved gradually from the surface to the inside. • Birefringence imaging was observed. • Morphology, size, and orientation of crystals were clarified. • Crystal lines with long lengths (e.g., 20 mm) were patterned at the depth of 200 μm.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Synthesis, crystal structure and properties of a new lead fluoride borate, Pb{sub 3}OBO{sub 3}F

Graphical abstract: The structure of Pb{sub 3}OBO{sub 3}F consists of two distortional Pb-centered tetrahedra and BO{sub 3} triangles which are all symmetrical with each other respectively in the gestalt structure to the extent that the Pb{sub 3}OBO{sub 3}F compound crystallizes in the symmetrical space group. Highlights: Black-Right-Pointing-Pointer Pb{sub 3}OBO{sub 3}F has been grown from PbO-PbF{sub 2}-B{sub 2}O{sub 3} system for the first time. Black-Right-Pointing-Pointer It crystallizes in the orthorhombic system, space group Pbcm. Black-Right-Pointing-Pointer Pb{sub 3}OBO{sub 3}F consists of Pb(1)O{sub 3}F tetrahedra, Pb(2)O{sub 4} tetrahedra and BO{sub 3} triangles. -- Abstract: A new compound, Pb{sub 3}OBO{sub 3}F, has been grown by the high temperature solution method from the PbO-PbF{sub 2}-B{sub 2}O{sub 3} system. It crystallizes in the orthorhombic system, space group Pbcm with unit-cell parameters a = 7.6313(14) Angstrom-Sign , b = 6.5229(12) Angstrom-Sign , c = 11.906(2) Angstrom-Sign , Z = 4, volume = 592.66(19) Angstrom-Sign {sup 3}. The structure of the compound is solved by the direct methods and refined to R{sub 1} = 0.0528 and wR{sub 2} = 0.1400. Pb{sub 3}OBO{sub 3}F consists of Pb(1)O{sub 3}F tetrahedra, Pb(2)O{sub 4} tetrahedra and BO{sub 3} triangles which build up the symmetrical chains extended along the c-axis. The powder X-ray diffraction pattern of the Pb{sub 3}OBO{sub 3}F has been measured. Functional groups presented in the sample were identified by Fourier transform infrared spectrum.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Magnetic properties and homogeneous distribution of Gd{sup 3+} ions in gadolinium molybdenum borate glass with high Gd{sub 2}O{sub 3} content

Highlights: ► The magnetic susceptibility of Gd{sub 2}O{sub 3}–MoO{sub 3}–B{sub 2}O{sub 3} glass was examined in T = 1.8–300 K. ► The effective magnetic moment was μ{sub eff} = 7.87 μ{sub B}. ► The Weiss constant was θ = −0.7 K. ► Gd{sup 3+} ions are distributed homogeneously as paramagnetic ions down to T = 1.8 K. -- Abstract: The magnetic susceptibility and specific heat of 21.25Gd{sub 2}O{sub 3}–63.75MoO{sub 3}–15B{sub 2}O{sub 3} (mol%) glass showing the crystallization of ferroelastic β′-Gd{sub 2}(MoO{sub 4}){sub 3} crystals are examined in the temperature range of T = 1.8–300 K to clarify magnetic and distribution states of Gd{sup 3+} ions. The magnetic susceptibility obeys the Curie–Weiss law, giving the effective magnetic moment of μ{sub eff} = 7.87 μ{sub B} and the Weiss constant of θ = −0.7 K. Any peak such as λ-type anomaly is not observed in the temperature dependence of specific heat in T = 1.8–5 K. It is suggested that Gd{sup 3+} ions in the glass with a high Gd{sub 2}O{sub 3} content of 21.25 mol% are distributed homogeneously and randomly as paramagnetic ions down to T = 1.8 K without inducing any strong magnetic interaction. The present study suggests that glasses based on the MoO{sub 3}–B{sub 2}O{sub 3} system are good hosts for the homogeneous solubility of a large amount of rare-earth oxides.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Thermodynamics and dehydration/hydration behaviors of Na-sulfate, -borate, and -bicarbonate minerals

Here, detailed thermal experiments using relative humidity- (RH) and temperature-controlled X-ray diffraction (XRD) and H 2 O adsorption/desorption measurements were applied to understand the dehydration/hydration behaviors of thenardite/mirabilite (Na 2 SO 4 /Na 2 SO 4 ·10H 2 O), tincalconite/borax (Na 2 B 4 O 7 ·5H 2 O/Na 2 B 4 O 7 ·10H 2 O), nahcolite (NaHCO 3 ), and qilianshanite (NaH 4 (BO 3 ) (CO 3 )·2H 2 O or NaHCO 3 ·H 3 BO 3 ·2H 2 O). The thermal behaviors of thenardite/mirabilite and tincalconite/borax were evaluated at room temperature as a function of RH. Hydration of thenardite to mirabilite is very sluggish and does not begin until at least 85 % RH, whereas dehydration of mirabilite to thenardite occurs at ~76 % RH. The reactions are accessible in the solid state and were not completely reversible on the time scale of these measurements. Qilianshanite appears stable under room conditions, as long as the RH is >20 %, supported by 2.5 months of observation during exposure to room air of known RH. Qilianshanite persists metastably for at least two days when exposed to both wet and 0% RH atmospheres at room temperature, observed during environment-controlled XRD. Below 20 % RH, qilianshanite sluggishly reacts to form tincalconite and nahcolite. When heated, qilianshanite broke down at 70 °C based on XRD results, and thermogravimetric analysis (TGA) confirmed a dehydration temperature of ~75 °C. Tincalconite hydrated to borax at 80 % RH, and dehydration from borax to tincalconite occurred at 40–50 % RH, illustrating the effective reversibility of the reaction under room conditions. The minor phase nahcolite originally in qilianshanite remained in the residue of decomposed qilianshanite after heating to 125 °C, demonstrated by continuous XRD measurements, whereas nahcolite was largely dehydrated when heated to ~100 °C during TGA. The difference can be attributed to the slower reaction kinetics in the environmental XRD. These results shed considerable light on the behavior of these minerals in the environment, particularly in evaporite deposits in Antarctica, where all of these minerals are reacting with the atmosphere on a diurnal-to-seasonal basis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗