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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 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

A Comparison of MOCLD With PLD Ba(x)Sr(1-x)TiO3 Thin Films on LaAlO3 for Tunable Microwave Applications

Historically, tunable dielectric devices using thin crystalline Ba(x)Sr(1-x)TiO3 (BST) films deposited on lattice-matched substrates, such as LaAlO3, have generally been grown using pulsed laser deposition (PLD). Highly oriented BST films can be grown by PLD but large projects are hampered by constraints of deposition area, deposition time and expense. The Metal-Organic Chemical Liquid Deposition (MOCLD) process allows for larger areas, faster turnover and lower cost. Several BST films deposited on LaAlO3 by MOCLD have been tested in 16 GHz coupled microstrip phase shifters. They can be compared with many PLD BST films tested in the same circuit design. The MOCLD phase shifter performance of 293 deg. phase shift with 53 V/micron dc bias and a figure of merit of 47 deg./dB is comparable to the most highly oriented PLD BST films. The PLD BST films used here have measured XRD full-width-at-half-maxima (FWHM) as low as 0.047 deg.. The best FWHM of these MOCLD BST films has been measured to be 0.058 deg.

VanKeuls, F. W.↗
NASA NTRS2003

A Comparison of MOCLD With PLD Ba(x)Sr(1-x)TiO3 Thin Films on LaAlO3 for Tunable Microwave Applications

Historically, tunable dielectric devices using thin crystalline Ba(x)Sr(1-x),TiO3 (BST) films deposited on lattice-matched substrates, such as LaAlO3 have generally been grown using pulsed laser deposition (PLD). Highly oriented BST films can be grown by PLD but large projects are hampered by constraints of deposition area, deposition time and expense. The Metal-Organic Chemical Liquid Deposition (MOCLD) process allows for larger areas, faster turnover and lower cost. Several BST films deposited on LaAlO, by MOCLD have been tested in 16 GHz coupled microstrip phase shifters. They can be compared with many PLD BST films tested in the same circuit design. The MOCLD phase shifter performance of 293 degree phase shift with 53 V/micron dc bias and a figure of merit of 47 degree/dB is comparable to the most highly oriented PLD BST films. The PLD BST films used here have measured XRD full-width-at-half-maxima (FWHM) as low as 0.047 degrees. The best FWHM of these MOCLD BST films has been measured to be 0.058 degrees.

VanKeuls, F. W.↗
NASA NTRS1997

Elastic Electron Scattering by Laser-Excited (sup 138)Ba (...6s6p (sup 1)P(sub 1)) Atoms

The result of a joint experimental and theoretical study concerning elastic electron scattering by laser-excited (sup 138)Ba (...6s6p (sup 1)P(sub 1)) atoms are presented. From these studies, we extracted differential scattering cross sections (DCS's) and collision parameters for elastic scattering by the coherently prepared (sup 1)P(sub 1) atoms.

collision elastic scattering convergent close-coup↗
NASA NTRS2001

A-site- and/or B-site-modified PbZrTiO3 materials and (Pb, Sr, Ca, Ba, Mg) (Zr, Ti, Nb, Ta)O3 films having utility in ferroelectric random access memories and high performance thin film microactuators

A modified PbZrTiO.sub.3 perovskite crystal material thin film, wherein the PbZrTiO.sub.3 perovskite crystal material includes crystal lattice A-sites and B-sites at least one of which is modified by the presence of a substituent selected from the group consisting of (i) A-site substituents consisting of Sr, Ca, Ba and Mg, and (ii) B-site substituents selected from the group consisting of Nb and Ta. The perovskite crystal thin film material may be formed by liquid delivery MOCVD from metalorganic precursors of the metal components of the thin film, to form PZT and PSZT, and other piezoelectric and ferroelectric thin film materials. The thin films of the invention have utility in non-volatile ferroelectric memory devices (NV-FeRAMs), and in microelectromechanical systems (MEMS) as sensor and/or actuator elements, e.g., high speed digital system actuators requiring low input power levels.

Roeder, Jeffrey F.↗
NASA NTRS2004

A-SITE-AND/OR B-SITE-MODIFIED PBZRTIO3 MATERIALS AND (PB, SR, CA, BA, MG) (ZR, TI,NB, TA)O3 FILMS HAVING UTILITY IN FERROELECTRIC RANDOM ACCESS MEMORIES AND HIGH PERFORMANCE THIN FILM MICROACTUATORS

A modified PbZrTiO.sub.3 perovskite crystal material thin film, wherein the PbZrTiO.sub.3 perovskite crystal material includes crystal lattice A-sites and B-sites at least one of which is modified by the presence of a substituent selected from the group consisting of (i) A-site substituents consisting of Sr, Ca, Ba and Mg, and (ii) B-site substituents selected from the group consisting of Nb and Ta. The perovskite crystal thin film material may be formed by liquid delivery MOCVD from metalorganic precursors of the metal components of the thin film, to form PZT and PSZT, and other piezoelectric and ferroelectric thin film materials. The thin films of the invention have utility in non-volatile ferroelectric memory devices (NV-FeRAMs), and in microelectromechanical systems (MEMS) as sensor and/or actuator elements, e.g., high speed digital system actuators requiring low input power levels.

Roeder, Jeffrey F.↗
NASA NTRS2014

Preparation Process and Dielectric Properties of Ba(0.5)Sr(0.5)TiO3-P(VDF-CTFE) Nanocomposites

Ceramic-polymer 0-3 nanocomposites, in which nanosized Ba(0.5)Sr(0.5)TiO3 (BST) powders were used as ceramic filler and P(VDF-CTFE) 88/12 mol% [poly(vinylidene fluoridechlorotrifluoroethylene)] copolymer was used as matrix, were studied over a concentration range from 0 to 50 vol.% of BST powders. It is found that the solution cast composites are porous and a hot-press process can eliminate the porosity, which results in a dense composite film. Two different configurations used in the hot-press process are studied. Although there is no clear difference in the uniformity and microstructure of the composites prepared using these two configurations, the composite prepared using one configuration exhibit a higher dielectric constant with a lower loss. For the composite with 40 vol. BST, a dielectric constant of 70 with a loss of 0.07 at 1 kHz is obtained at room temperature. The composites exhibit a lower dielectric loss than the polymer matrix at high frequency. However, at low frequency, the composites exhibit a higher loss than the polymer matrix due to a low frequency relaxation process that appears in the composites. It is believed that this relaxation process is related to the interfacial layer formed between BST particle and the polymer matrix. The temperature dependence of the dielectric property of the composites was studied. It is found that the dielectric constant of these composites is almost independent of the temperature over a temperature range from 20 to 120 C. Key words: A. Polymer-matrix composites (PMCs); B. Electrical Properties; E. Casting; E. Heat treatment; Dielectric properties.

Zhang, Lin↗
DOE OSTI2020

Materials Data on Ba(CoO2)4 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(SnO2)4 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(C2O5)2 by Materials Project

BaO2(CO2)4 is Cyanogen Chloride-like structured and crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of sixteen carbon dioxide molecules and four caustic baryta molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(Fe2O3)9 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(WO3)6 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(Mo3O5)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(FeO2)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(ZnN)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2022

Low‐Loss Tunable Infrared Plasmons in the High‐Mobility Perovskite (Ba,La)SnO 3

Abstract BaSnO 3 exhibits the highest carrier mobility among perovskite oxides, making it ideal for oxide electronics. Collective charge carrier oscillations known as plasmons are expected to arise in this material, thus providing a tool to control the nanoscale optical field for optoelectronics applications. Here, the existence of relatively long‐lived plasmons supported by high‐mobility charge carriers in La‐doped BaSnO 3 (BLSO) is demonstrated. By exploiting the high spatial and energy resolution of electron energy‐loss spectroscopy with a focused beam in a scanning transmission electron microscope, the dispersion, confinement ratio, and damping of infrared localized surface plasmons (LSPs) in BLSO nanoparticles are systematically investigated. It is found that LSPs in BLSO exhibit a high degree of spatial confinement compared to those sustained by noble metals and have relatively low losses and high quality factors with respect to other doped oxides. Further analysis clarifies the relation between plasmon damping and carrier mobility in BLSO. The results support the use of nanostructured degenerate semiconductors for plasmonic applications in the infrared region and establish a solid alternative to more traditional plasmonic materials.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Ag Alloying in Cu 2– y Ag y Ba(Ge,Sn)Se 4 Films and Photovoltaic Devices

Trigonal Cu 2 BaGe 1–x Sn x Se 4 (CBGTSe) has recently gained interest as a potential photovoltaic absorber to target mitigation of antisite defect formation in Cu 2 ZnSn(S,Se) 4 . This study examines partial substitution of Cu by Ag as a potential approach to tune the properties of Ag-incorporated CBGTSe in the following aspects: 1) phase stability and crystal structure as a function of Ag content; 2) film morphology and grain structure; 3) charge carrier properties; 4) band positions; and 5) charge carrier kinetics and recombination. Up to 20% of Cu can be substituted by Ag in CBGTSe, while above 20% a phase mixture appears. Increasing Ag content induces larger average grain size and reduced hole carrier densities. In contrast, photoelectron spectroscopy and photoluminescence measurements reveal negligible impact of Ag substitution on ionization potential (≈5.4 eV) and electron affinity (≈3.7 eV). Also, Ag content offers negligible impact on carrier lifetimes (few ns). Consistent with these fundamental properties, solar cells based on two different Ag/(Ag + Cu) ratios (≈0% and ≈20%) show comparable power conversion efficiencies (≈2.7–2.8%). Finally, these results indicate that CBGTSe films and solar cells may be less sensitive to Ag substitution compared to Cu 2 ZnSn(S,Se) 4 , at least at the current level of absorber and device optimization.

14 SOLAR ENERGY↗