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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1957

Results of turbojet engine operation tests using a 50-50 mixture of JP-4 and tributyl borate as the fuel

An experimental investigation was conducted on a centrifugal-type turbojet engine using a 50-50 mixture of tributyl borate and JP-4 as the fuel to determine the magnitude and the location of the boric oxide deposits in the engine as well as the effect of these deposits on the engine performance. Large deposits of boric acid formed in the combustor walls and on the turbine rotor and stator blades. The deposits had no effect on the engine thrust.

Schafer, Louis J , Jr↗
DOE OSTI2013

Tetrakis(1-imidazolyl) borate (BIM4) based zwitterionic and related molecules used as electron injection layers

Tetrakis(1-imidazolyl)borate (BIm4) based zwitterionic and/or related molecules for the fabrication of PLEDs is provided. Device performances with these materials approaches that of devices with Ba/Al cathodes for which the cathode contact is ohmic. Methods of producing such materials, and electron injection layers and devices containing these materials are also provided.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Ligand field and spectroscopic investigations of cobalt doped erbium–zinc borate glasses

The glasses of the composition [xCoO–(29.5 − x)Na{sub 2}O–55B{sub 2}O{sub 3}–15ZnO–0.5Er{sub 2}O{sub 3}] (where x = 0, 0.3, 0.5, 1 and 3 mol%) have been prepared using melt quenching technique. The recorded UV/VIS/NIR absorption spectra have been studied and the resulting data was used for the ligand field theory analysis, from which the crystal field energy (10Dq), Racah parameters (B, C) and nephelauxetic ratio (β) were evaluated. The observed variations in the band gap and Urbach energy with CoO content have been discussed in relation with the glass structure. FT-IR spectra of the samples exhibit modes of vibration corresponding to the stretching of BO{sub 3} and BO{sub 4} unit. From IR studies, the number of non-bridging oxygens was increased, leading to loosen structure at higher CoO concentrations. The ESR spectra revealed that Co{sup 2+} ions are located both in distorted tetrahedral and octahedral sites.

36 MATERIALS SCIENCE↗
DOE OSTI2018

A Study on Passive and Electrochemical Response of Pure Nickel in Borate Buffer Solutions: Effect of Cold Deformation

In the present work, influences of the cold deformation on electrochemical and passive response of pure nickel in three solutions with adjusted pH values of 8.5, 9.0, and 9.5 at 298 ± 1 K (25 ± 1 °C) were investigated. A cold deformation process was applied by means of cold rolling. Implementation of the cold deformation process resulted in samples having a finer microstructure. Also, the cold work and grain refinement led to increased hardness. In addition, open-circuit potential and potentiodynamic polarization tests were performed and results showed that corrosion current density was reduced by applying the cold deformation. Moreover, the results of the electrochemical impedance spectroscopy and Mott–Schottky analyses indicated higher corrosion resistance of pure nickel after cold deformation. This behavior is attributed to the growth of much thicker, with less point defects, passive layer on the surface of cold-deformed samples.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Synthesis, crystal structure and optical properties of the new lead fluoride borate-Pb{sub 2}BO{sub 3}F

A new compound, Pb{sub 2}BO{sub 3}F, has been grown by high temperature solution method from the PbO-PbF{sub 2}-B{sub 2}O{sub 3} system for the first time. The crystal structure of this compound has been identified by single crystal X-ray diffraction analysis. It crystallizes in the hexagonal system, space group P6{sub 3}/m (No. 176) with unit-cell parameters a=7.2460(3) A, c=14.5521(17) A, Z=6, V=661.69(9) A{sup 3}. Its structure was solved by the direct methods and refined to R{sub 1}=0.0163 and wR{sub 2}=0.0367. The structure of Pb{sub 2}BO{sub 3}F consists of the distorted PbO{sub 3}F{sub 2} groups and BO{sub 3} triangles, which are all symmetric with each other in the gestalt structure to the extent that the Pb{sub 2}BO{sub 3}F compound crystallizes in the symmetric space group. The powder X-ray diffraction pattern of the Pb{sub 2}BO{sub 3}F has been measured. The BO{sub 3} functional groups presented in the sample were identified by FTIR spectrum. The DTA curve of Pb{sub 2}BO{sub 3}F suggests that Pb{sub 2}BO{sub 3}F melts congruently at 448 deg. C. - Graphical Abstract: The Pb atoms are in the five coordination environments bonded to three O atoms and two F atoms to make up the distortional PbO{sub 3}F{sub 2} polyhedra. Every six PbO{sub 3}F{sub 2} polyhedra are connected by one F(1) atom to form the symmetrical structure, and then the distortion of the PbO{sub 3}F{sub 2} polyhedra is offset. Highlights: > A new compound, Pb{sub 2}BO{sub 3}F, has been grown by high temperature solution method from the PbO-PbF{sub 2}-B{sub 2}O{sub 3} system for the first time. > It crystallizes in the hexagonal system, space group P6{sub 3}/m (No. 176) with unit-cell parameters a=7.2460(3) A, c=14.5521(17) A, Z=6, V=661.69(9) A{sup 3}. > UV-vis-NIR Diffuse-Reflectance spectrum shows that its ultraviolet cutoff edge is about 288 nm. > DTA curve of Pb{sub 2}BO{sub 3}F suggests that Pb{sub 2}BO{sub 3}F melts congruently at 448 deg. C.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Bismuth borate zinc glass braze for bonding sapphire in air

Highlights: • Sapphire was brazed with a novel 50Bi{sub 2}O{sub 3}–40B{sub 2}O{sub 3}–10ZnO (mol.%) glass at temperatures of 600–700 °C for 20 min in air. • Bi{sub 4}B{sub 2}O{sub 9} and Bi{sub 24}B{sub 2}O{sub 39} were formed in the joints brazed at 600 and 625 °C, respectively. • ZnAl{sub 2}O{sub 4} particles were formed in the joints when the brazing temperature was 635 °C. • The maximum shear strength of 85 MPa was obtained for the joints brazed at 650 °C for 20 min. - Abstract: Reliable brazing of sapphire was successfully achieved by using a novel 50Bi{sub 2}O{sub 3}–40B{sub 2}O{sub 3}–10ZnO (mol%) glass braze and joining cycles that peak at temperatures of 600 − 700 °C for 20 min in air. The effect of the brazing temperature on microstructure evolution as well as mechanical properties of the sapphire/sapphire joints was investigated. The results showed that Bi{sub 4}B{sub 2}O{sub 9} and Bi{sub 24}B{sub 2}O{sub 39} were formed in the joints brazed at 600 and 625 °C, respectively. ZnAl{sub 2}O{sub 4} particles were formed in the joints when the brazing temperature was 635 °C due to a reaction between the glass and the sapphire substrate. With the brazing temperature increasing, ZnAl{sub 2}O{sub 4} particles exhibited steady growth, from ~ 160 nm at 635 °C to ~ 455 nm at 700 °C. Besides, ZnAl{sub 2}O{sub 4} particles began to aggregate when the temperature was 675 °C. The strength increased sharply when the brazing temperature increased to 635 °C, which was mainly attributed to the formation of ZnAl{sub 2}O{sub 4} particles in the joint domain. The maximum shear strength of 85 MPa was obtained for the joints brazed at 650 °C for 20 min. The joint shear strength decreased due to the aggregation of ZnAl{sub 2}O{sub 4} particles in the joint.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Effect of substituting iron on structural, thermal and dielectric properties of lithium borate glasses

Highlights: • There is increase in NBOs with iron content. • FTIR spectra supported the results predicted by density. • Glass stability has been examined. • Iron shows “blocking effect” on migration of mobile ions. • Internal Circuit varies with temperature and composition. - Abstract: Glasses with composition xFe{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%) were prepared via melt-quenching technique and their physical, thermal and dielectric properties are discussed. XRD was carried out to confirm the amorphous nature of prepared glasses. Density (ρ) and molar volume (V{sub m}) were found to increase with increase in Fe{sub 2}O{sub 3} content. Infrared absorption spectra depicted that Fe{sub 2}O{sub 3} is acting as a network modifier. DTA has been carried out to determine glass transition temperature (T{sub g}) and crystallization temperature (T{sub x}). Electrical properties have been studied using impedance spectroscopy and dc conductivity. The dc conductivity decreases and activation energy increases on replacing Li{sup +} ions with Fe{sup 3+}. The impedance measurements reveal that the total conductivity obeys Jonscher’s power law. Study of the equivalent circuit analysis up to a temperature of 523 K shows a significant change in the equivalent circuitry with change in temperature and composition.

36 MATERIALS SCIENCE↗
DOE OSTI2011

On the Electron Paramagnetic Resonance Studies in Mixed Alkali Borate Glasses

Mixed alkali effect in oxide based glasses is one of the current research activity and studies on the behavior of spectroscopic parameters in these systems are quite important to understand the basic nature of this phenomenon. EPR studies of mixed alkali glasses Li{sub 2}O-K{sub 2}O-ZnO-B{sub 2}O{sub 3} doped with Fe{sup 3+} and Mn{sup 2+} were carried out at room temperature. The EPR spectra show typical resonances of d{sup 5} system (Fe{sup 3+} and Mn{sup 2+}) in all the measured glass specimens. Evaluated hyperfine constant, number of paramagnetic centers and paramagnetic susceptibility values show deviation from the linearity with the progressive substitution of the Li ion with K in glass network.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Structural and physical properties of vanadium doped copper bismuth borate glasses

The structural and physical properties of xCuO(30-x)Bi{sub 2}O{sub 3}-70B{sub 2}O{sub 3}; x= 0, 5, 10, 15, 20 and 25 mol % with 2 mol %V{sub 2}O{sub 5} glasses prepared by normal melt quench technique have been investigated by means of FT-IR and physical measurement techniques. With the addition of copper oxide (x{<=} 10 mol%), the frequency bands in the higher region shift towards lower wave number, suggest the conversion of BO{sub 3} to BO{sub 4} structural units, which in turn give rise to the formation of Non Bridging Oxygen's (NBOs). For further increase in CuO (i.e. for x{>=} 10 mol %), the frequency bands shift towards higher wave number, indicate the formation of Bridging Oxygen's (BOs). The FTIR analysis reveals that the present glass system is based on the BiO{sub 3} pyramidal, BiO{sub 6} octahedral units and also on BO{sub 3} and BO{sub 4} structural units. The systematic variation in density and molar volume in these glasses indicates the effect of CuO substitution.

36 MATERIALS SCIENCE↗
DOE OSTI2013

XRD and FTIR structural investigation of gadolinium-zinc-borate glass ceramics

X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy measurements have been employed to investigate the (Gd{sub 2}O{sub 3}){sub x}⋅(B{sub 2}O{sub 3}){sub (60−x)}⋅(ZnO){sub 40} glass ceramics system, with 0 ≤ x ≤ 15 mol%. After heat treatment applied at 860 °C for 2 h, some structural changes were observed and new crystalline phases appeared in the structure of the samples. In these glass ceramics four crystalline phases were identified using powder diffraction files (PDF 2), namely ZnB{sub 4}O{sub 7}, Zn{sub 4}O(B{sub 6}O{sub 12}), Zn{sub 3}(BO{sub 3}){sub 2} and GdBO{sub 3}. From the XRD data, the average unit-cell parameter and the quantitative ratio of the crystallographic phases in the studied samples were evaluated. FTIR data revealed that the BO{sub 3}, BO{sub 4} and ZnO{sub 4} are the main structural units of these glass ceramics network. The compositional dependence of the different structural units which appear in the studied samples was followed.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Magnetic behavior of erbium-zinc-borate glasses and glass ceramics

Glasses of the system (Er{sub 2}O{sub 3}){sub x}⋅(B{sub 2}O{sub 3}){sub (60−x)}⋅(ZnO){sub 40} (3 ≤ x ≤ 15 mol%) were prepared by conventional melt quenching and subsequently converted to glass ceramics by heat treatment of glass samples at 860 °C for 2 h. The magnetic behaviour of the studied glasses and glass ceramics were investigated using a vibrating sample magnetometer (VSM) and a Faraday-type magnetic balance. Magnetic data show that erbium ions are involved in negative superexchange interactions in all the investigated samples, being antiferromagnetically coupled. For all studied samples the experimental values obtained for the effective magnetic moments are lower than the value corresponding to free Er{sup 3+} ions and decrease with the increasing of Er{sub 2}O{sub 3} content. The decrease is more pronounced in heat treated samples than untreated ones.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Elastic properties of silver borate glasses doped with praseodymium oxide

A series of glasses xPr{sub 6}O{sub 11−}(35−x) Ag{sub 2}O−65B{sub 2}O{sub 3} with x=0, 0.1, 0.2, 0.3, 0.4 and 0.5 mol % were synthesized by melt quenching technique. Longitudinal and shear ultrasonic velocity were measured at 5 MHz frequency and at room temperature. Elastic moduli, Poisson's ratio and Debye temperature have been calculated from the measured density and ultrasonic velocity at room temperature. The experimental results indicate that the elastic constants depend upon the composition of the glasses. The role of the Pr{sub 6}O{sub 11} inside the glass network was discussed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

Study of lithium borate glasses containing Bi{sub 2}O{sub 3}

The effect of Bi{sub 2}O{sub 3} addition on the properties of 30Li{sub 2}O:(70−x)B{sub 2}O{sub 3}:xBi{sub 2}O{sub 3} (0≤x≤35 mol %) has been studied. Density and molar volume are increasing with Bi{sub 2}O{sub 3} content. The observed decrease in glass transition temperature and optical band gap has been explained on the basis of increase in non bridging oxygen which is supported by infrared spectroscopy. From the optical transmittance spectra it is observed that the cut off wavelength increases with Bi{sub 2}O{sub 3} content which is related to the structural changes.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

Growth and characterization of lithium yttrium borate single crystals

Single crystals of 0.1% Ce doped Li{sub 6}Y(BO{sub 3}){sub 3} have been grown using the Czochralski technique. The photoluminescence study of these crystals shows a broad emission at ∼ 420 nm corresponding to Ce{sub 3+} emission from 5d→4f energy levels. The decay profile of this emission shows a fast response of ∼ 28 ns which is highly desirable for detector applications.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Structural study and DC conductivity of vanadyl doped zinc lithium borate glasses

Glasses with composition xZnO⋅(30 − x)⋅Li{sub 2}O⋅70B{sub 2}O{sub 3} containing 2 mol% of V{sub 2}O{sub 5} (x = 0, 2, 5, 7 and 10) were prepared by standard melt-quench technique. The amorphous nature of the glass samples was confirmed by using x-ray diffraction. The structural changes in these glasses have been investigated by employing IR spectroscopy in the mid-IR range. The infrared spectroscopic analysis confirms the presence of both triangular and tetraheldral coordinated boron units and absence of boroxol ring. It also shows that metal-oxide vibrations are present which are due to the bonding of lithium and zinc ions with oxygen. The dc conductivity was measured in the temperature range 353-523 K. The dc conductivity results show that conductivity decreases and activation energy increases when Li{sub 2}O is replaced by ZnO, keeping the concentration of B{sub 2}O{sub 3} constant. Decrease in conductivity and increase in activation energy shows that addition of ZnO to the glass matrix shows a “blocking effect” on the overall mobility of alkali ions, but at higher concentration the hopping effect was also observed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Effect of mixed transition metal ions on DC conductivity in lithium bismuth borate glasses

The DC conductivities of glasses having composition x(2NiO·V{sub 2}O{sub 5})·(30-x)Li{sub 2}O·20Bi{sub 2}O{sub 3}·50B{sub 2}O{sub 3} (with x=0, 2, 5, 7 and 10, i.e. NVLBB glasses) and glass samples having composition 7NiO·23 Li{sub 2}O·20Bi{sub 2}O{sub 3}·50B{sub 2}O{sub 3} and 7V{sub 2}O{sub 5}·23Li{sub 2}O·20Bi{sub 2}O{sub 3}·50B{sub 2}O{sub 3} (NLBB and VLBB respectively) are investigated as a function of temperature. Conductivity for glasses containing higher percentage of lithium ions is predominantly ionic and in glasses containing higher percentage of transition metal (TM) ions is predominantly electronic. The observed increase in conductivity with x and peak-like behavior at x=7 in NVLBB glasses due to competitive transport of small polaron contributing to a significant structural change in NVLBB glasses. Variation of molar volume and density was also observed with x. In NVLBB glasses, as x increases density increases except a slight decrease at x=7. Also density increases in NLBB whereas in case of VLBB it decreases in comparison to NVLBB1 glass composition. Mott’s small polaron hopping (SPH) model has been applied to analyze the high temperature conductivity data and activation energy.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Temperature dependent electrical transport characteristics of BaTiO{sub 3} modified lithium borate glasses

The glass samples with composition (70B{sub 2}O{sub 3}-29Li{sub 2}O-1Dy{sub 2}O{sub 3})-xBT; x = 0, 10 and 20 weight percent, have been prepared by conventional melt quench technique. The dielectric measurements as a function of temperature have been carried out on these samples in the frequency range 1 Hz-10 MHz. The dielectric relaxation characteristics of these samples have been studied by analyzing dielectric spectroscopy, dielectric loss, electric modulus formulation and electrical conductivity spectroscopy. It is found that the dielectric permittivity of the samples increases with an increase in the temperature and BT content. The frequency dependent ac conductivity has been analyzed using Jonscher’s universal power law whereas non exponential KWW function has been invoked to fit the experimental data of the imaginary part of the electric modulus. The values of the activation energy determined from the electric modulus and that from dc conductivity have been found to be quite close to each other suggesting that the same type of charge barriers are involved in the relaxation and the conduction mechanisms. The stretched exponent (β) and the power exponent (n) have been found to be temperature and composition dependent. The decrease in n with an increase in temperature further suggested that the ac conduction mechanism of the studied samples follows the correlated barrier hopping (CBH) model.

36 MATERIALS SCIENCE↗