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11 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Epitaxially Grown Single-Crystalline SrTiO 3 Membranes Using a Solution-Processed, Amorphous SrCa 2 Al 2 O 6 Sacrificial Layer

Water-soluble sacrificial layers based on epitaxially-grown, single crystalline (Ca, Sr, Ba) 3 Al 2 O 6 layer are widely used for creating free-standing perovskite oxide membranes. However, obtaining these sacrificial layers with intricate stoichiometry remains a challenge, especially for molecular beam epitaxy (MBE). In this study, we demonstrate the hybrid MBE growth of epitaxial, single crystalline SrTiO 3 films using a solution processed, amorphous SrCa 2 Al 2 O 6 sacrificial layer onto SrTiO 3 (001) substrates. Prior to the growth, the oxygen plasma exposure was used to first create the crystalline SrCa 2 Al 2 O 6 layer with well-defined surface crystallinity. Utilizing reflection high energy electron diffraction, x-ray diffraction, and atomic force microscopy, we observe an atomic layer-by-layer growth of epitaxial, single crystalline SrTiO 3 film on the SrCa 2 Al 2 O 6 layer with atomically smooth surfaces. The SrCa 2 Al 2 O6 layer was subsequently dissolved in de-ionized water to create free-standing SrTiO3 membranes that were transferred onto a metal-coated Si wafer. Membranes created with Sr-deficiency revealed ferroelectric-like behavior measured using piezo force microscopy whereas stoichiometric films remained paraelectric-like. Furthermore, these findings underscore the viability of using ex-situ deposited amorphous SrCa2Al2O6 for epitaxial, single crystalline growth, as well as the importance of point defects in determining the ferroic properties in membranes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

The development and application of the stirred‐reactor coupon analysis (SRCA) test method

A new technique, termed the stirred‐reactor coupon analysis (SRCA) method, has been developed to measure the rate of glass dissolution in forward‐rate conditions. Monolithic glass coupons are partially masked with an inert material before placement in a large volume of well‐mixed solution with known chemistry and temperature for a predetermined duration. After the test, the mask is removed, and the difference in step height between the protected area and the exposed corroded portions of the sample coupon is measured to determine the extent of glass dissolution. The step height is converted to a rate measurement using the test duration and glass density. Test parameters such as sample surface preparation and test duration were evaluated to determine their effects on the measured rates. Additionally, results from an interlaboratory study (ILS) consisting of 12 laboratories from 11 different institutions are presented, where each laboratory performed 12 independent tests. When removing experimental outlier data, the 95% reproducibility limits for the SRCA method has no statistical difference with previously published standardized test methods used to determine the forward rate of glass dissolution. Overall, this paper describes steps necessary to perform the test method and provides the statistical calculations to evaluate test accuracy.

chemical durability↗
DOE OSTI2020

Materials Data on SrCa(CO3)2 by Materials Project

SrCa(CO3)2 crystallizes in the orthorhombic Pmc2_1 space group. The structure is three-dimensional. Sr2+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Sr–O bond distances ranging from 2.60–2.80 Å. Ca2+ is bonded to seven O2- atoms to form distorted edge-sharing CaO7 pentagonal bipyramids. There are a spread of Ca–O bond distances ranging from 2.40–2.50 Å. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.29 Å) and two longer (1.30 Å) C–O bond length. In the second C4+ site, C4+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.27 Å) and two longer (1.31 Å) C–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one Sr2+, two equivalent Ca2+, and one C4+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Sr2+, one Ca2+, and one C4+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Sr2+ and one C4+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Sr2+, one Ca2+, and one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SrCa(CoO3)2 by Materials Project

SrCa(CoO3)2 is (Cubic) Perovskite-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are three inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with four equivalent CaO12 cuboctahedra, corners with eight SrO12 cuboctahedra, faces with two equivalent SrO12 cuboctahedra, faces with four CaO12 cuboctahedra, and faces with eight equivalent CoO6 octahedra. There are eight shorter (2.71 Å) and four longer (2.72 Å) Sr–O bond lengths. In the second Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with twelve CaO12 cuboctahedra, faces with two equivalent CaO12 cuboctahedra, faces with four equivalent SrO12 cuboctahedra, and faces with eight equivalent CoO6 octahedra. All Sr–O bond lengths are 2.72 Å. In the third Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with four equivalent CaO12 cuboctahedra, corners with eight equivalent SrO12 cuboctahedra, faces with six CaO12 cuboctahedra, and faces with eight equivalent CoO6 octahedra. There are eight shorter (2.71 Å) and four longer (2.72 Å) Sr–O bond lengths. There are three inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to twelve O2- atoms to form CaO12 cuboctahedra that share corners with four equivalent SrO12 cuboctahedra, corners with eight CaO12 cuboctahedra, faces with two equivalent CaO12 cuboctahedra, faces with four SrO12 cuboctahedra, and faces with eight equivalent CoO6 octahedra. There are four shorter (2.69 Å) and eight longer (2.71 Å) Ca–O bond lengths. In the second Ca2+ site, Ca2+ is bonded to twelve O2- atoms to form CaO12 cuboctahedra that share corners with twelve SrO12 cuboctahedra, faces with two equivalent SrO12 cuboctahedra, faces with four equivalent CaO12 cuboctahedra, and faces with eight equivalent CoO6 octahedra. All Ca–O bond lengths are 2.69 Å. In the third Ca2+ site, Ca2+ is bonded to twelve O2- atoms to form CaO12 cuboctahedra that share corners with four equivalent SrO12 cuboctahedra, corners with eight equivalent CaO12 cuboctahedra, faces with six SrO12 cuboctahedra, and faces with eight equivalent CoO6 octahedra. There are four shorter (2.69 Å) and eight longer (2.71 Å) Ca–O bond lengths. Co4+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six equivalent CoO6 octahedra, faces with four SrO12 cuboctahedra, and faces with four CaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–1°. There is five shorter (1.91 Å) and one longer (1.92 Å) Co–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to two Sr2+, two Ca2+, and two equivalent Co4+ atoms. In the second O2- site, O2- is bonded in a distorted linear geometry to two Sr2+, two Ca2+, and two equivalent Co4+ atoms. In the third O2- site, O2- is bonded in a distorted linear geometry to three Sr2+, one Ca2+, and two equivalent Co4+ atoms. In the fourth O2- site, O2- is bonded in a distorted linear geometry to one Sr2+, three Ca2+, and two equivalent Co4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SrCa by Materials Project

SrCa crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Sr is bonded to six equivalent Sr and six equivalent Ca atoms to form SrSr6Ca6 cuboctahedra that share corners with eighteen equivalent SrSr6Ca6 cuboctahedra, edges with six equivalent SrSr6Ca6 cuboctahedra, edges with twelve equivalent CaSr6Ca6 cuboctahedra, faces with eight equivalent SrSr6Ca6 cuboctahedra, and faces with twelve equivalent CaSr6Ca6 cuboctahedra. All Sr–Sr bond lengths are 4.12 Å. All Sr–Ca bond lengths are 4.06 Å. Ca is bonded to six equivalent Sr and six equivalent Ca atoms to form CaSr6Ca6 cuboctahedra that share corners with eighteen equivalent CaSr6Ca6 cuboctahedra, edges with six equivalent CaSr6Ca6 cuboctahedra, edges with twelve equivalent SrSr6Ca6 cuboctahedra, faces with eight equivalent CaSr6Ca6 cuboctahedra, and faces with twelve equivalent SrSr6Ca6 cuboctahedra. All Ca–Ca bond lengths are 4.12 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SrCa by Materials Project

SrCa is alpha La-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Sr sites. In the first Sr site, Sr is bonded to six equivalent Sr and six Ca atoms to form SrSr6Ca6 cuboctahedra that share corners with twelve SrSr6Ca6 cuboctahedra, edges with twelve SrSr6Ca6 cuboctahedra, edges with twelve CaSr6Ca6 cuboctahedra, faces with six equivalent SrSr6Ca6 cuboctahedra, and faces with twelve CaSr6Ca6 cuboctahedra. All Sr–Sr bond lengths are 4.08 Å. All Sr–Ca bond lengths are 4.08 Å. In the second Sr site, Sr is bonded to ten equivalent Sr and six Ca atoms to form SrSr10Ca6 cuboctahedra that share corners with ten CaSr6Ca6 cuboctahedra, corners with twelve SrSr6Ca6 cuboctahedra, edges with eight CaSr6Ca6 cuboctahedra, edges with sixteen SrSr6Ca6 cuboctahedra, faces with sixteen equivalent SrSr10Ca6 cuboctahedra, and faces with eighteen CaSr6Ca6 cuboctahedra. There are a spread of Sr–Sr bond distances ranging from 4.08–8.17 Å. All Sr–Ca bond lengths are 4.08 Å. There are three inequivalent Ca sites. In the first Ca site, Ca is bonded to six equivalent Sr and six equivalent Ca atoms to form CaSr6Ca6 cuboctahedra that share corners with twelve CaSr6Ca6 cuboctahedra, edges with twelve equivalent SrSr6Ca6 cuboctahedra, edges with twelve CaSr6Ca6 cuboctahedra, faces with six equivalent CaSr6Ca6 cuboctahedra, and faces with twelve equivalent SrSr6Ca6 cuboctahedra. All Ca–Ca bond lengths are 4.08 Å. In the second Ca site, Ca is bonded to six Sr and six equivalent Ca atoms to form CaSr6Ca6 cuboctahedra that share corners with five equivalent SrSr10Ca6 cuboctahedra, corners with twelve CaSr6Ca6 cuboctahedra, edges with ten SrSr6Ca6 cuboctahedra, edges with twelve CaSr6Ca6 cuboctahedra, faces with six equivalent CaSr6Ca6 cuboctahedra, and faces with fifteen SrSr6Ca6 cuboctahedra. All Ca–Sr bond lengths are 4.08 Å. All Ca–Ca bond lengths are 4.08 Å. In the third Ca site, Ca is bonded to six Sr and six equivalent Ca atoms to form CaSr6Ca6 cuboctahedra that share corners with five equivalent SrSr10Ca6 cuboctahedra, corners with twelve CaSr6Ca6 cuboctahedra, edges with ten SrSr6Ca6 cuboctahedra, edges with twelve CaSr6Ca6 cuboctahedra, faces with six equivalent CaSr6Ca6 cuboctahedra, and faces with fifteen SrSr6Ca6 cuboctahedra. All Ca–Ca bond lengths are 4.08 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SrCa by Materials Project

SrCa is beta-prime cadmium gold-like structured and crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. Sr is bonded in a distorted body-centered cubic geometry to four equivalent Sr and four equivalent Ca atoms. All Sr–Sr bond lengths are 3.98 Å. All Sr–Ca bond lengths are 3.93 Å. Ca is bonded in a distorted body-centered cubic geometry to four equivalent Sr and four equivalent Ca atoms. All Ca–Ca bond lengths are 3.98 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SrCa(Ni2Sn)4 by Materials Project

SrCa(Ni2Sn)4 crystallizes in the tetragonal I422 space group. The structure is three-dimensional. Sr is bonded in a 8-coordinate geometry to eight equivalent Ni and eight Sn atoms. All Sr–Ni bond lengths are 3.11 Å. All Sr–Sn bond lengths are 3.53 Å. Ca is bonded in a 8-coordinate geometry to eight equivalent Ni and eight Sn atoms. All Ca–Ni bond lengths are 3.08 Å. All Ca–Sn bond lengths are 3.53 Å. Ni is bonded in a 10-coordinate geometry to one Sr, one Ca, four equivalent Ni, and four Sn atoms. There are a spread of Ni–Ni bond distances ranging from 2.52–2.83 Å. There are a spread of Ni–Sn bond distances ranging from 2.58–2.66 Å. There are three inequivalent Sn sites. In the first Sn site, Sn is bonded in a 12-coordinate geometry to two equivalent Sr, two equivalent Ca, and eight equivalent Ni atoms. In the second Sn site, Sn is bonded in a 12-coordinate geometry to two equivalent Sr, two equivalent Ca, and eight equivalent Ni atoms. In the third Sn site, Sn is bonded in a 12-coordinate geometry to two equivalent Sr, two equivalent Ca, and eight equivalent Ni atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SrCa(CuO2)2 by Materials Project

SrCa(CuO2)2 crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Sr2+ is bonded to seven O2- atoms to form distorted SrO7 pentagonal bipyramids that share corners with four equivalent SrO7 pentagonal bipyramids, edges with two equivalent SrO7 pentagonal bipyramids, edges with four equivalent CaO7 pentagonal bipyramids, and faces with two equivalent SrO7 pentagonal bipyramids. There are a spread of Sr–O bond distances ranging from 2.42–2.65 Å. Ca2+ is bonded to seven O2- atoms to form distorted CaO7 pentagonal bipyramids that share corners with four equivalent CaO7 pentagonal bipyramids, edges with two equivalent CaO7 pentagonal bipyramids, edges with four equivalent SrO7 pentagonal bipyramids, and faces with two equivalent CaO7 pentagonal bipyramids. There are a spread of Ca–O bond distances ranging from 2.38–2.64 Å. There are two inequivalent Cu2+ sites. In the first Cu2+ site, Cu2+ is bonded in a square co-planar geometry to four O2- atoms. There are a spread of Cu–O bond distances ranging from 1.88–1.97 Å. In the second Cu2+ site, Cu2+ is bonded in a square co-planar geometry to four O2- atoms. There are a spread of Cu–O bond distances ranging from 1.95–1.97 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to two equivalent Sr2+ and three Cu2+ atoms to form OSr2Cu3 trigonal bipyramids that share corners with seven OSrCa4Cu octahedra, corners with four equivalent OSr2Cu3 trigonal bipyramids, edges with two equivalent OCa2Cu3 trigonal bipyramids, and faces with two equivalent OSr4CaCu octahedra. The corner-sharing octahedra tilt angles range from 0–59°. In the second O2- site, O2- is bonded to two equivalent Ca2+ and three Cu2+ atoms to form OCa2Cu3 trigonal bipyramids that share corners with seven OSrCa4Cu octahedra, corners with four equivalent OCa2Cu3 trigonal bipyramids, edges with two equivalent OSr2Cu3 trigonal bipyramids, and faces with two equivalent OSrCa4Cu octahedra. The corner-sharing octahedra tilt angles range from 0–59°. In the third O2- site, O2- is bonded to one Sr2+, four equivalent Ca2+, and one Cu2+ atom to form distorted OSrCa4Cu octahedra that share corners with four equivalent OSrCa4Cu octahedra, corners with seven OSr2Cu3 trigonal bipyramids, edges with eight OSrCa4Cu octahedra, and faces with two equivalent OCa2Cu3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 8°. In the fourth O2- site, O2- is bonded to four equivalent Sr2+, one Ca2+, and one Cu2+ atom to form distorted OSr4CaCu octahedra that share corners with four equivalent OSr4CaCu octahedra, corners with seven OSr2Cu3 trigonal bipyramids, edges with eight OSrCa4Cu octahedra, and faces with two equivalent OSr2Cu3 trigonal bipyramids. The corner-sharing octahedral tilt angles are 10°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SrCa(CuO2)2 by Materials Project

SrCa(CuO2)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sr2+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Sr–O bond lengths are 2.58 Å. Ca2+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Ca–O bond lengths are 2.58 Å. Cu2+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Cu–O bond lengths are 1.96 Å. O2- is bonded to two equivalent Sr2+, two equivalent Ca2+, and two equivalent Cu2+ atoms to form a mixture of corner, edge, and face-sharing OSr2Ca2Cu2 octahedra. The corner-sharing octahedra tilt angles range from 0–65°.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Stirred-Reactor Coupon Analysis: An International Round Robin Study

The objective of this task was to determine the precision of the SRCA technique when used to determine the dilute condition corrosion rate. To this end, an interlaboratory round robin study was conducted per the instructions in ASTM Practice E691 to measure the precision with which the SRCA test method can be conducted. Twelve independent labs from eleven different institutions each evaluated four glass compositions in three different conditions. The ASTM procedures recommend at least 6 labs participate in a round robin testing the same 3 materials in the same conditions to determine precision. In this case, 12 labs each performed 12 independent tests. This was only possible thanks to the multi-glass testing capability of the SRCA test. A total of 108 duplicate pairs were used to calculate the repeatability of the tests, with the same glass tested in the same vessel, producing as identical conditions as possible for the replicates. These test results were quite tightly clustered, with a median difference from the average value of the pair of only 2.9%. Based on the calculations outlined in ASTM E177-20 and a measured standard deviation of 4.74%, the intralaboratory repeatability limit (r) was calculated to be within 13.3% of the expected value with 95% confidence level. The reproducibility limit (R) of the test was examined using all 277 data points from the round robin. Because of the differences in dissolution rates due to pH variability and intrinsically for the 12 conditions tested, the reproducibility limits for each condition and overall were calculated from the percent relative residual value for each test. The SRCA test is expected to be reproducible within 64% of the expected value with a 95% confidence level.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗