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9 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on KNO3 by Materials Project

KNO3 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.82–3.01 Å. N5+ is bonded in a trigonal planar geometry to three O2- atoms. All N–O bond lengths are 1.27 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one N5+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to three equivalent K1+ and one N5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KNO3 by Materials Project

KNO3 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of K–O bond distances ranging from 2.89–2.97 Å. N5+ is bonded in a trigonal planar geometry to three O2- atoms. All N–O bond lengths are 1.27 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one N5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one N5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KNO3 by Materials Project

KNO3 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.78–3.03 Å. In the second K1+ site, K1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of K–O bond distances ranging from 2.76–3.00 Å. There are two inequivalent N5+ sites. In the first N5+ site, N5+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.27 Å) and one longer (1.28 Å) N–O bond length. In the second N5+ site, N5+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.26 Å) and two longer (1.27 Å) N–O bond length. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two K1+ and one N5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to three K1+ and one N5+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two K1+ and one N5+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to three K1+ and one N5+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to three K1+ and one N5+ atom. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent K1+ and one N5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KNO3 by Materials Project

KNO3 is Calcite-like structured and crystallizes in the trigonal R32 space group. The structure is three-dimensional. K1+ is bonded to six equivalent O2- atoms to form distorted corner-sharing KO6 octahedra. The corner-sharing octahedral tilt angles are 67°. All K–O bond lengths are 2.78 Å. N5+ is bonded in a trigonal planar geometry to three equivalent O2- atoms. All N–O bond lengths are 1.27 Å. O2- is bonded in a trigonal planar geometry to two equivalent K1+ and one N5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KNO3 by Materials Project

KNO3 crystallizes in the trigonal R3m space group. The structure is three-dimensional. K1+ is bonded in a 9-coordinate geometry to nine equivalent O2- atoms. There are three shorter (2.84 Å) and six longer (2.96 Å) K–O bond lengths. N5+ is bonded in a trigonal planar geometry to three equivalent O2- atoms. All N–O bond lengths are 1.27 Å. O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one N5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on KNO3 by Materials Project

KNO3 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. K1+ is bonded in a 11-coordinate geometry to eleven O2- atoms. There are a spread of K–O bond distances ranging from 2.82–3.23 Å. N5+ is bonded in a trigonal planar geometry to three O2- atoms. All N–O bond lengths are 1.27 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to four equivalent K1+ and one N5+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to three equivalent K1+ and one N5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Chemical compatibility of hollow ceramic cenospheres as thermal insulation for high-temperature thermal energy storage applications with molten nitrate salt

An effective insulation material that is both thermally and chemically stable in molten salts could transform the design of molten-salt-based thermal energy storage (TES) tanks. Most current molten salt TES tanks hold the metallic tank structure in direct contact with hot salt inventory, a design which leads to thermal expansion of the tank and triggers stresses that can lead to thermomechanical failures. With an internal insulation to lower the temperature at the tank structure, the extent of thermal expansion can be reduced, thereby reducing expansion-induced stresses and allowing for consideration of lower-cost tank structure materials. Conventional insulation materials are either 1) too porous and allow molten salts to permeate into the matrix, which significantly increases the thermal conductivity or 2) too dense and have a thermal conductivity that cannot provide sufficient thermal insulation. This paper presents an alternative thermal insulation concept using cenospheres which have an alumino-silicate structure. The cost analysis suggests that the low-density cenospheres can be one of the cheapest materials to provide cost-effective thermal insulation. The chemical compatibility of cenospheres is investigated in molten 60 wt% NaNO3/40 wt% KNO3 salt which is close to industrial-grade Solar Salt. This paper shows that diffusion of the sodium and potassium cations from the salt into the cenospheres occurs based on weight analysis, energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy. The cation diffusion breaks the bridging oxygen bonds and causes volume expansion of the microstructure which is responsible for the failure of the cenosphere particles. The chemical composition of the cenospheres is found to affect their compatibility with molten nitrate salt. A cenosphere product with low iron content showed the best compatibility with an average survival rate of 77.9% +/- 9.8% after 7 days of immersion in the molten nitrate salt. While even the low-iron cenospheres appear to require protection from direct molten salt contact, their slow degradation rate, closed-cell porosity, and low cost hold potential for effective use as internal tank insulation.

14 SOLAR ENERGY↗
DOE OSTI2022

Corrosion resistance of high nickel alloys in solar salt at 600 °C for up to 4000 h

This study focuses on the time dependent performance of the corrosion resistance of IN625, H230 and 740H alloys in the solar salt (60 wt% NaNO3, 40 wt% KNO3, at 600 °C) for up to 4000 h. Alloy IN625 showed the lowest mass change with parabolic oxidation kinetics that tends to stabilize with exposure time. Both 740H and H230 alloys deviated from the parabolic oxidation behavior beyond the 3000 h of exposure. Alloy 740H showed the highest mass loss due to the nonuniform surface oxidation and the high chromium dissolution rate. Internal oxidation was noticed with Alloy H230 due to the high tungsten concentrations.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on K8NO3 by Materials Project

K8NO3 is Fluorite-derived structured and crystallizes in the cubic Pm-3m space group. The structure is three-dimensional. K1+ is bonded to one N2- and three equivalent O2- atoms to form a mixture of edge and corner-sharing KNO3 tetrahedra. The K–N bond length is 2.88 Å. All K–O bond lengths are 2.83 Å. N2- is bonded in a body-centered cubic geometry to eight equivalent K1+ atoms. O2- is bonded in a body-centered cubic geometry to eight equivalent K1+ atoms.

36 MATERIALS SCIENCE↗