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10 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on KHo(PO3)4 by Materials Project

KHo(PO3)4 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. K1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of K–O bond distances ranging from 2.76–2.97 Å. Ho3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.33–2.42 Å. There are two inequivalent P5+ sites. In the first P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.62 Å. In the second P5+ site, P5+ is bonded to four O2- atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.63 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Ho3+ and one P5+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one K1+ and two P5+ atoms. In the third O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, one Ho3+, and one P5+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to one Ho3+ and one P5+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to one K1+, one Ho3+, and one P5+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two P5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KHO by Materials Project

KHO crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. K1+ is bonded in a 2-coordinate geometry to three equivalent H1+ and five equivalent O2- atoms. There are a spread of K–H bond distances ranging from 2.63–2.82 Å. There are a spread of K–O bond distances ranging from 2.71–2.97 Å. H1+ is bonded in a single-bond geometry to three equivalent K1+ and one O2- atom. The H–O bond length is 0.98 Å. O2- is bonded in a single-bond geometry to five equivalent K1+ and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KHO by Materials Project

KHO crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. K1+ is bonded in a 9-coordinate geometry to four equivalent H1+ and five equivalent O2- atoms. There are two shorter (2.71 Å) and two longer (2.87 Å) K–H bond lengths. There are a spread of K–O bond distances ranging from 2.69–2.88 Å. H1+ is bonded in a single-bond geometry to four equivalent K1+ and one O2- atom. The H–O bond length is 0.98 Å. O2- is bonded in a single-bond geometry to five equivalent K1+ and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KHO by Materials Project

KHO crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. K1+ is bonded in a 9-coordinate geometry to four equivalent H1+ and five equivalent O2- atoms. There are a spread of K–H bond distances ranging from 2.69–3.04 Å. There are a spread of K–O bond distances ranging from 2.67–2.94 Å. H1+ is bonded in a single-bond geometry to four equivalent K1+ and one O2- atom. The H–O bond length is 0.97 Å. O2- is bonded in a single-bond geometry to five equivalent K1+ and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KHo(CO3)2 by Materials Project

KHo(CO3)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. K1+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of K–O bond distances ranging from 2.80–3.40 Å. Ho3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.27–2.48 Å. C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.28–1.32 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to two equivalent K1+, one Ho3+, and one C4+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent K1+, one Ho3+, and one C4+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to one K1+, two equivalent Ho3+, and one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Morphology, microstructure, and doping behaviour: A comparison between different deposition methods for poly-Si/SiO x passivating contacts

In this work, we study how crystallographic structures, optoelectronic properties, and nanoscale surface morphologies of ex situ phosphorus-doped polycrystalline silicon (poly-Si)/SiO x passivating contacts, formed by different deposition methods (sputtering, plasma-enhanced chemical vapour deposition [PECVD], and low-pressure chemical vapour deposition [LPCVD]), are investigated and compared. Across all these deposition technologies, we noted the same trend: higher diffusion temperatures yield films that are more crystalline but that have rougher surface morphologies due to bigger surface crystal grains. Also, the recrystallization process of the as-deposited Si films starts from the SiO x interface, rather than from the film surface and bulk. However, there are some distinct differences among these technologies. First, the LPCVD method yields the lowest deposition rate, roughest surfaces, and smallest degree of crystallinity on finished poly-Si films. In contrast, the PECVD method has the highest deposition rate and smoothest surfaces for both as-deposited Si and annealed poly-Si films. Second, as-deposited sputtered and PECVD Si films contain only an amorphous phase, whereas as-deposited LPCVD films already has some crystalline phase. Third, the LPCVD phosphorus in-diffusion into the substrate depends strongly on the initial film thickness, whereas for the other two methods, it is weakly dependent on thickness. Finally, the passivation quality of every poly-Si film type has different responses to the film thickness and diffusion temperature, suggesting that the ex situ doping optimization should be performed independently.

14 SOLAR ENERGY↗
DOE OSTI2023

Litterfall and Branchfall Mass Flux in Malaysia Lambir Hills GEM plots (2008-2010)

This data package includes two folders: Litterfall and Branchfall. The Litterfall folder includes three files: "GEM_Lambir_Hills_Litterfall_Mass_Flux_Data_2008_to_2010.csv" includes the litterfall data, the "GEM_Lambir_Hills_Litterfall_Metadata.xlx" includes the descripion of the columns in the data file, and the PDF file "GEM_Lambir_Hills_Litterfall_Methods_Description" includes a brief description of the litterfall sampling methods. The Branchfall Folder includes four files: the "GEM_Lambir_Hills_Branchfall_Data_2009_to_2010.csv" file includes the branchfall data, the "GEM_Lambir_Hills_Branchfall_Metadata_2009_to_2010.xlsx" includes the description of the columns in the csv data file, the "GEM_Lambir_Hills_Branchfall_Methods_Description.pdf" includes a brief description of the branchfall collection methods, and the "GEM_Lambir_Hills_Branchfall_Data_Metadata_Methods_TransectSums.xlx" includes data, metadata, methods description, and a 'TransectsSums' tab where the reader can find the sum of the branchfall data in each transect Litterfall and Branchfall data were collected to quantify canopy productivity and net primary productivity allocated to branch turnover, which are components of the total net primary productivity and ecosystem carbon budget. The methods follow the Global Ecosystems Monitoring (GEM) protocols (see gem.tropicalforests.ox.ac.uk). The data collection took place from 2008 to 2010 in two 1-ha GEM plots in Lambir Hills National Park, Sarawak, Malaysia, within the Lambir 52-ha ForestGEO plots. One of the plots was located on clay soil and the other on sandy loam. The site is an old-growth moist tropical forest dominated by Dipterocarpacea. The climate is moist tropical and aseasonal. Litterfall was collected biweekly from 25 litter traps per plot. Branchfall was estimated using four 100-m transects, which were surveyed every two months.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2026

The DREAMS Project: Disentangling the Impact of Halo-to-halo Variance and Baryonic Feedback on Milky Way Dark Matter Density Profiles

In this work, we utilize a new suite of Milky Way–mass halos from the DREAMS Project, simulated with cold dark matter (CDM), to quantify the influence of baryon feedback and intrinsic halo-to-halo variance on dark matter density profiles. Our suite of 1024 halos varies over supernova and black hole feedback parameters from the IllustrisTNG model, as well as variations in two cosmological parameters. We find that, for the DREAMS parameter variations, Milky Way–mass dark matter density profiles in the IllustrisTNG model are largely insensitive to astrophysics and cosmology variations, with the dominant source of scatter instead arising from halo-to-halo variance. However, most of the (comparatively minor) feedback-driven variations come from the changes to supernova prescriptions. By comparing to dark-matter-only simulations, we find that the strongest supernova wind energies are so effective at preventing galaxy formation that the halos are nearly entirely collisionless dark matter. Finally, regardless of physics variation, all of the DREAMS halos are roughly consistent with a halo contracting adiabatically from the presence of baryons, unlike models that have bursty stellar feedback. This work represents a step toward assessing the uncertainty in Milky Way dark matter profiles, with direct implications for dark matter searches where systematic uncertainty in the density profile remains a major challenge.

Garcia, Alex M. [University of Virginia, Charlotte↗