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All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Improving tubular protonic ceramic fuel cell performance by compensating Ba evaporation via a Ba-excess optimized proton conducting electrolyte synthesis strategy

Protonic ceramic fuel cells (PCFCs) are emerging as a promising technology for reduced temperature ceramic energy conversion devices. The BaCe 0.4 Zr 0.4 Y 0.1 Yb 0.1 O 3–δ (BCZYYb4411) electrolyte is notable for its high proton conductivity. However, the tendency of barium to volatilize in BCZYYb4411 during high-temperature sintering compromises its chemical stability and performance. This study investigates the effects of intentionally incorporating excess barium into BCZYYb4411, formulated as Ba 1+x Ce 0.4 Zr 0.4 Y0.1Yb 0.1 O 3–δ (where x = 0, 0.1, 0.2, and 0.3), with the aim of compensating barium evaporation and enhancing the physical and chemical properties. We find that excess barium results in a greater shrinkage rate, facilitating a denser electrolyte structure. This barium-enriched electrolyte demonstrates improved electrochemical performance by effectively counteracting the deleterious effects of barium evaporation. Applying this strategy to tubular PCFCs, we achieved a peak power density of 480 mW•cm –2 at 600 °C. This unique approach provides a simple, tunable, and easy-to-implement processing modification to achieve high-performance tubular PCFC.

25 ENERGY STORAGE↗
DOE OSTI2023

Formation of Ba 3 Nb 0.75 Mn 2.25 O 9 -6H during thermochemical reduction of Ba 4 NbMn 3 O 12 -12R

The resurgence of interest in hydrogen-related technologies has stimulated new studies aimed at advancing lesser-developed water-splitting processes, such as solar thermochemical hydrogen production (STCH). Progress in STCH has been largely hindered by a lack of new materials able to efficiently split water at a rate comparable to ceria under identical experimental conditions. BaCe 0.25 Mn 0.75 O 3 (BCM) recently demonstrated enhanced hydrogen production over ceria and has the potential to further our understanding of two-step thermochemical cycles. A significant feature of the 12R hexagonal perovskite structure of BCM is the tendency to, in part, form a 6H polytype at high temperatures and reducing environments ( i.e. , during the first step of the thermochemical cycle), which may serve to mitigate degradation of the complex oxide. An analogous compound, namely BaNb 0.25 Mn 0.75 O 3 (BNM) with a 12R structure was synthesized and displays nearly complete conversion to the 6H structure under identical reaction conditions as BCM. The structure of the BNM-6H polytype was determined from Rietveld refinement of synchrotron powder X-ray diffraction data and is presented within the context of the previously established BCM-6H structure.

08 HYDROGEN↗
DOE OSTI2020

Materials Data on Ba(H8O5)2 by Materials Project

(Ba(H8O5)2)2(Ba(H5O3)3)2H2O2 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of one water molecule; one Ba(H5O3)3 sheet oriented in the (0, 0, 1) direction; and one Ba(H8O5)2 sheet oriented in the (0, 0, 1) direction. In the Ba(H5O3)3 sheet, Ba is bonded in a 9-coordinate geometry to one H and eight O atoms. The Ba–H bond length is 2.68 Å. There are a spread of Ba–O bond distances ranging from 2.68–2.90 Å. There are fifteen inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the second H site, H is bonded in a 2-coordinate geometry to one Ba and two O atoms. There is one shorter (1.04 Å) and one longer (1.56 Å) H–O bond length. In the third H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the fourth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the fifth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.97 Å. In the sixth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.07 Å) and one longer (1.44 Å) H–O bond length. In the seventh H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the eighth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.04 Å) and one longer (1.53 Å) H–O bond length. In the ninth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the tenth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.09 Å) and one longer (1.40 Å) H–O bond length. In the eleventh H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.97 Å. In the twelfth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the thirteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the fourteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the fifteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. There are nine inequivalent O sites. In the first O site, O is bonded in a distorted bent 150 degrees geometry to two H atoms. In the second O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the third O site, O is bonded in a distorted water-like geometry to one Ba and two H atoms. In the fourth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the fifth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the sixth O site, O is bonded in a distorted water-like geometry to one Ba and two H atoms. In the seventh O site, O is bonded in a 3-coordinate geometry to one Ba and three H atoms. In the eighth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the ninth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the Ba(H8O5)2 sheet, Ba is bonded in a 9-coordinate geometry to one H and eight O atoms. The Ba–H bond length is 2.73 Å. There are a spread of Ba–O bond distances ranging from 2.79–2.98 Å. There are sixteen inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.01 Å. In the second H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.66 Å) H–O bond length. In the third H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the fourth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the fifth H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.63 Å) H–O bond length. In the sixth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the seventh H site, H is bonded in a 1-coordinate geometry to one Ba and two O atoms. There is one shorter (1.04 Å) and one longer (1.56 Å) H–O bond length. In the eighth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the ninth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.03 Å) and one longer (1.58 Å) H–O bond length. In the tenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the eleventh H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the twelfth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.01 Å. In the thirteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the fourteenth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.09 Å) and one longer (1.41 Å) H–O bond length. In the fifteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the sixteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.97 Å. There are ten inequivalent O sites. In the first O site, O is bonded in a 4-coordinate geometry to three H and one O atom. The O–O bond length is 1.48 Å. In the second O site, O is bonded in a single-bond geometry to one H and one O atom. In the third O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the fourth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the fifth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the sixth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the seventh O site, O is bonded in a distorted water-like geometry to one Ba and two H atoms. In the eighth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the ninth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the tenth O site, O is bonded in a 3-coordinate geometry to one Ba and three H atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(PO4)2 by Materials Project

Ba(PO4)2 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are three inequivalent Ba sites. In the first Ba site, Ba is bonded in a 6-coordinate geometry to nine O atoms. There are a spread of Ba–O bond distances ranging from 2.63–3.36 Å. In the second Ba site, Ba is bonded in a 9-coordinate geometry to nine O atoms. There are a spread of Ba–O bond distances ranging from 2.70–3.16 Å. In the third Ba site, Ba is bonded in a 9-coordinate geometry to nine O atoms. There are a spread of Ba–O bond distances ranging from 2.66–3.18 Å. There are six inequivalent P sites. In the first P site, P is bonded to four O atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. In the second P site, P is bonded to four O 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 third P site, P is bonded to four O atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.65 Å. In the fourth P site, P is bonded to four O atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.63 Å. In the fifth P site, P is bonded to four O atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.63 Å. In the sixth P site, P is bonded to four O atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.63 Å. There are twenty-four inequivalent O sites. In the first O site, O is bonded in a bent 120 degrees geometry to two P atoms. In the second O site, O is bonded in a bent 120 degrees geometry to two P atoms. In the third O site, O is bonded in a bent 120 degrees geometry to two P atoms. In the fourth O site, O is bonded in a bent 120 degrees geometry to two P atoms. In the fifth O site, O is bonded in a bent 120 degrees geometry to two P atoms. In the sixth O site, O is bonded in a bent 120 degrees geometry to two P atoms. In the seventh O site, O is bonded in a distorted single-bond geometry to two equivalent Ba and one P atom. In the eighth O site, O is bonded in a distorted single-bond geometry to two Ba and one P atom. In the ninth O site, O is bonded in a distorted single-bond geometry to two Ba and one P atom. In the tenth O site, O is bonded in a distorted single-bond geometry to two Ba and one P atom. In the eleventh O site, O is bonded in a distorted single-bond geometry to two Ba and one P atom. In the twelfth O site, O is bonded in a distorted single-bond geometry to two Ba and one P atom. In the thirteenth O site, O is bonded in a distorted single-bond geometry to two equivalent Ba and one P atom. In the fourteenth O site, O is bonded in a distorted single-bond geometry to one Ba and one P atom. In the fifteenth O site, O is bonded in a distorted single-bond geometry to two Ba and one P atom. In the sixteenth O site, O is bonded in a distorted single-bond geometry to one Ba and one P atom. In the seventeenth O site, O is bonded in a distorted bent 150 degrees geometry to one Ba and one P atom. In the eighteenth O site, O is bonded in a distorted single-bond geometry to two Ba and one P atom. In the nineteenth O site, O is bonded in a water-like geometry to two Ba atoms. In the twentieth O site, O is bonded in a single-bond geometry to one Ba atom. In the twenty-first O site, O is bonded in a distorted single-bond geometry to two equivalent Ba and one O atom. The O–O bond length is 1.24 Å. In the twenty-second O site, O is bonded in a 2-coordinate geometry to one Ba and one O atom. The O–O bond length is 1.28 Å. In the twenty-third O site, O is bonded in a bent 120 degrees geometry to two O atoms. The O–O bond length is 1.29 Å. In the twenty-fourth O site, O is bonded in a single-bond geometry to one O atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(PO4)2 by Materials Project

Ba3(P3O11)2O2 crystallizes in the triclinic P-1 space group. The structure is three-dimensional and consists of two hydrogen peroxide molecules and one Ba3(P3O11)2 framework. In the Ba3(P3O11)2 framework, there are three inequivalent Ba sites. In the first Ba site, Ba is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ba–O bond distances ranging from 2.60–3.24 Å. In the second Ba site, Ba is bonded in a 9-coordinate geometry to nine O atoms. There are a spread of Ba–O bond distances ranging from 2.70–3.15 Å. In the third Ba site, Ba is bonded in a 9-coordinate geometry to nine O atoms. There are a spread of Ba–O bond distances ranging from 2.66–3.13 Å. There are six inequivalent P sites. In the first P site, P is bonded to four O atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.50–1.62 Å. In the second P site, P is bonded to four O atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.63 Å. In the third P site, P is bonded to four O atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.66 Å. In the fourth P site, P is bonded to four O atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.63 Å. In the fifth P site, P is bonded to four O 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 sixth P site, P is bonded to four O atoms to form corner-sharing PO4 tetrahedra. There are a spread of P–O bond distances ranging from 1.49–1.63 Å. There are twenty-two inequivalent O sites. In the first O site, O is bonded in a bent 120 degrees geometry to two P atoms. In the second O site, O is bonded in a bent 120 degrees geometry to two P atoms. In the third O site, O is bonded in a bent 120 degrees geometry to two P atoms. In the fourth O site, O is bonded in a bent 120 degrees geometry to two P atoms. In the fifth O site, O is bonded in a bent 120 degrees geometry to two P atoms. In the sixth O site, O is bonded in a bent 120 degrees geometry to two P atoms. In the seventh O site, O is bonded in a distorted single-bond geometry to two equivalent Ba and one P atom. In the eighth O site, O is bonded in a distorted single-bond geometry to two Ba and one P atom. In the ninth O site, O is bonded in a distorted single-bond geometry to two Ba and one P atom. In the tenth O site, O is bonded in a distorted single-bond geometry to two Ba and one P atom. In the eleventh O site, O is bonded in a distorted single-bond geometry to two Ba and one P atom. In the twelfth O site, O is bonded in a single-bond geometry to two Ba and one P atom. In the thirteenth O site, O is bonded in a distorted single-bond geometry to two equivalent Ba and one P atom. In the fourteenth O site, O is bonded in a distorted single-bond geometry to one Ba and one P atom. In the fifteenth O site, O is bonded in a distorted single-bond geometry to two Ba and one P atom. In the sixteenth O site, O is bonded in a distorted single-bond geometry to one Ba and one P atom. In the seventeenth O site, O is bonded in a distorted bent 150 degrees geometry to one Ba and one P atom. In the eighteenth O site, O is bonded in a distorted single-bond geometry to two Ba and one P atom. In the nineteenth O site, O is bonded in a bent 120 degrees geometry to two Ba atoms. In the twentieth O site, O is bonded in a distorted single-bond geometry to two equivalent Ba and one O atom. The O–O bond length is 1.24 Å. In the twenty-first O site, O is bonded in a bent 150 degrees geometry to one Ba and one O atom. The O–O bond length is 1.23 Å. In the twenty-second O site, O is bonded in a single-bond geometry to one O atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(H8O5)2 by Materials Project

Ba(H8O5)2 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of two Ba(H8O5)2 sheets oriented in the (0, 0, 1) direction. In one of the Ba(H8O5)2 sheets, Ba is bonded in a body-centered cubic geometry to eight O atoms. There are a spread of Ba–O bond distances ranging from 2.74–2.88 Å. There are sixteen inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the third H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the fourth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.06 Å) and one longer (1.49 Å) H–O bond length. In the fifth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.01 Å. In the sixth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the seventh H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.03 Å) and one longer (1.59 Å) H–O bond length. In the eighth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the ninth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.03 Å) and one longer (1.60 Å) H–O bond length. In the tenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the eleventh H site, H is bonded in a single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.71 Å) H–O bond length. In the twelfth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the thirteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the fourteenth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.61 Å) H–O bond length. In the fifteenth H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.67 Å) H–O bond length. In the sixteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. There are ten inequivalent O sites. In the first O site, O is bonded in a 2-coordinate geometry to two H and one O atom. The O–O bond length is 1.49 Å. In the second O site, O is bonded in a 5-coordinate geometry to four H and one O atom. In the third O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the fourth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the fifth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the sixth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the seventh O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the eighth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the ninth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the tenth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In one of the Ba(H8O5)2 sheets, Ba is bonded in a body-centered cubic geometry to eight O atoms. There are a spread of Ba–O bond distances ranging from 2.72–2.88 Å. There are sixteen inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the second H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.64 Å) H–O bond length. In the third H site, H is bonded in a single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.70 Å) H–O bond length. In the fourth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the fifth H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.68 Å) H–O bond length. In the sixth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the seventh H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.64 Å) H–O bond length. In the eighth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the ninth H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.68 Å) H–O bond length. In the tenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the eleventh H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.03 Å) and one longer (1.60 Å) H–O bond length. In the twelfth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the thirteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the fourteenth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.05 Å) and one longer (1.51 Å) H–O bond length. In the fifteenth H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.00 Å) and one longer (1.70 Å) H–O bond length. In the sixteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. There are ten inequivalent O sites. In the first O site, O is bonded in a 5-coordinate geometry to four H and one O atom. The O–O bond length is 1.49 Å. In the second O site, O is bonded in a 5-coordinate geometry to four H and one O atom. In the third O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the fourth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the fifth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the sixth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the seventh O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the eighth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the ninth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the tenth O site, O is bonded in a water-like geometry to one Ba and two H atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(BO4)2 by Materials Project

Ba(BO4)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Ba sites. In the first Ba site, Ba is bonded in a 7-coordinate geometry to nine O atoms. There are a spread of Ba–O bond distances ranging from 2.73–3.14 Å. In the second Ba site, Ba is bonded in a 9-coordinate geometry to nine O atoms. There are a spread of Ba–O bond distances ranging from 2.78–3.22 Å. There are four inequivalent B sites. In the first B site, B is bonded in a tetrahedral geometry to four O atoms. There are a spread of B–O bond distances ranging from 1.43–1.47 Å. In the second B site, B is bonded in a tetrahedral geometry to four O atoms. There are a spread of B–O bond distances ranging from 1.43–1.46 Å. In the third B site, B is bonded in a tetrahedral geometry to four O atoms. There are a spread of B–O bond distances ranging from 1.43–1.48 Å. In the fourth B site, B is bonded in a tetrahedral geometry to four O atoms. There are a spread of B–O bond distances ranging from 1.42–1.47 Å. There are sixteen inequivalent O sites. In the first O site, O is bonded in a distorted single-bond geometry to one Ba and one B atom. In the second O site, O is bonded in a distorted single-bond geometry to one Ba and one B atom. In the third O site, O is bonded in a single-bond geometry to one Ba and one B atom. In the fourth O site, O is bonded in a single-bond geometry to one Ba and one B atom. In the fifth O site, O is bonded in a single-bond geometry to one Ba and one B atom. In the sixth O site, O is bonded in a single-bond geometry to two Ba and one B atom. In the seventh O site, O is bonded in a distorted single-bond geometry to one Ba and one B atom. In the eighth O site, O is bonded in a distorted single-bond geometry to one Ba and one B atom. In the ninth O site, O is bonded in a single-bond geometry to one Ba and one B atom. In the tenth O site, O is bonded in a distorted single-bond geometry to one Ba and one B atom. In the eleventh O site, O is bonded in a distorted single-bond geometry to one Ba and one B atom. In the twelfth O site, O is bonded in a single-bond geometry to one Ba and one B atom. In the thirteenth O site, O is bonded in a distorted single-bond geometry to one Ba and one B atom. In the fourteenth O site, O is bonded in a distorted single-bond geometry to one Ba and one B atom. In the fifteenth O site, O is bonded in a single-bond geometry to two Ba and one B atom. In the sixteenth O site, O is bonded in a single-bond geometry to one Ba and one B atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(H2O3)2 by Materials Project

Ba(H2O3)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent Ba sites. In the first Ba site, Ba is bonded in a 9-coordinate geometry to nine O atoms. There are a spread of Ba–O bond distances ranging from 2.79–2.94 Å. In the second Ba site, Ba is bonded in a 12-coordinate geometry to two H and ten O atoms. There are one shorter (2.90 Å) and one longer (2.91 Å) Ba–H bond lengths. There are a spread of Ba–O bond distances ranging from 2.69–3.08 Å. There are eight inequivalent H sites. In the first H site, H is bonded in a linear geometry to one Ba and two O atoms. There is one shorter (1.11 Å) and one longer (1.35 Å) H–O bond length. In the second H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.22 Å) and one longer (1.23 Å) H–O bond length. In the third H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.06 Å) and one longer (1.46 Å) H–O bond length. In the fourth H site, H is bonded in a single-bond geometry to one Ba and one O atom. The H–O bond length is 0.99 Å. In the fifth H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.64 Å) H–O bond length. In the sixth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.04 Å) and one longer (1.49 Å) H–O bond length. In the seventh H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.08 Å) and one longer (1.44 Å) H–O bond length. In the eighth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.09 Å) and one longer (1.40 Å) H–O bond length. There are twelve inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to two Ba and one H atom. In the second O site, O is bonded in a single-bond geometry to two Ba and one H atom. In the third O site, O is bonded in a distorted single-bond geometry to two Ba and one H atom. In the fourth O site, O is bonded in a single-bond geometry to two Ba and one H atom. In the fifth O site, O is bonded in a single-bond geometry to two Ba and one H atom. In the sixth O site, O is bonded in a single-bond geometry to one Ba and one H atom. In the seventh O site, O is bonded in a single-bond geometry to two Ba and one H atom. In the eighth O site, O is bonded in a single-bond geometry to one Ba and one H atom. In the ninth O site, O is bonded in a 2-coordinate geometry to one Ba and two H atoms. In the tenth O site, O is bonded in a 1-coordinate geometry to one Ba and two H atoms. In the eleventh O site, O is bonded in a single-bond geometry to two Ba and one H atom. In the twelfth O site, O is bonded in a 2-coordinate geometry to one Ba and two H atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(H2O3)2 by Materials Project

Ba(H2O3)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent Ba sites. In the first Ba site, Ba is bonded in a 1-coordinate geometry to one H and ten O atoms. The Ba–H bond length is 2.76 Å. There are a spread of Ba–O bond distances ranging from 2.58–3.18 Å. In the second Ba site, Ba is bonded in a 1-coordinate geometry to nine O atoms. There are a spread of Ba–O bond distances ranging from 2.60–3.28 Å. There are eight inequivalent H sites. In the first H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.07 Å) and one longer (1.48 Å) H–O bond length. In the second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the third H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.06 Å) and one longer (1.49 Å) H–O bond length. In the fourth H site, H is bonded in a distorted linear geometry to one Ba and two O atoms. There is one shorter (1.07 Å) and one longer (1.43 Å) H–O bond length. In the fifth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.97 Å. In the sixth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the seventh H site, H is bonded in a distorted single-bond geometry to one O atom. The H–O bond length is 1.01 Å. In the eighth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. There are twelve inequivalent O sites. In the first O site, O is bonded in a single-bond geometry to two Ba and one H atom. In the second O site, O is bonded in a single-bond geometry to two Ba and one H atom. In the third O site, O is bonded in a 3-coordinate geometry to two Ba and one O atom. The O–O bond length is 1.38 Å. In the fourth O site, O is bonded in a water-like geometry to two Ba and two H atoms. In the fifth O site, O is bonded in a single-bond geometry to one Ba and one H atom. In the sixth O site, O is bonded in a single-bond geometry to two Ba and one H atom. In the seventh O site, O is bonded in a distorted single-bond geometry to two Ba, one H, and one O atom. In the eighth O site, O is bonded in a distorted single-bond geometry to two Ba and one H atom. In the ninth O site, O is bonded in a distorted single-bond geometry to one Ba and one H atom. In the tenth O site, O is bonded in a 2-coordinate geometry to one Ba and one O atom. The O–O bond length is 1.33 Å. In the eleventh O site, O is bonded in a distorted bent 120 degrees geometry to one Ba and two H atoms. In the twelfth O site, O is bonded in a water-like geometry to one Ba and one O atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(H2O3)2 by Materials Project

Ba(H2O3)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent Ba sites. In the first Ba site, Ba is bonded in a 12-coordinate geometry to ten O atoms. There are a spread of Ba–O bond distances ranging from 2.74–3.11 Å. In the second Ba site, Ba is bonded in a 9-coordinate geometry to nine O atoms. There are a spread of Ba–O bond distances ranging from 2.75–3.13 Å. There are eight inequivalent H sites. In the first H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.04 Å) and one longer (1.58 Å) H–O bond length. In the second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the third H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the fourth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the fifth H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.04 Å) and one longer (1.59 Å) H–O bond length. In the sixth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the seventh H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the eighth H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.06 Å) and one longer (1.51 Å) H–O bond length. There are twelve inequivalent O sites. In the first O site, O is bonded in a distorted L-shaped geometry to one Ba and one O atom. The O–O bond length is 1.34 Å. In the second O site, O is bonded in a distorted single-bond geometry to two Ba and one H atom. In the third O site, O is bonded in a 4-coordinate geometry to two Ba and one O atom. The O–O bond length is 1.36 Å. In the fourth O site, O is bonded in a single-bond geometry to two Ba and one H atom. In the fifth O site, O is bonded in a 1-coordinate geometry to two equivalent Ba and one O atom. In the sixth O site, O is bonded in a single-bond geometry to one Ba and one H atom. In the seventh O site, O is bonded in a 1-coordinate geometry to one Ba and one O atom. In the eighth O site, O is bonded in a single-bond geometry to two equivalent Ba and one H atom. In the ninth O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the tenth O site, O is bonded in a single-bond geometry to two Ba and one H atom. In the eleventh O site, O is bonded in a water-like geometry to one Ba and two H atoms. In the twelfth O site, O is bonded in a 2-coordinate geometry to two Ba and two H atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Experimental Investigation of Barium Sources and Fluid–Rock Interaction in Unconventional Marcellus Shale Wells Using Ba Isotopes

Produced waters from unconventional Marcellus Shale gas wells have anomalously high barium (Ba) concentrations and yield some of the isotopically heaviest Ba measured to date. Experiments were conducted to constrain the source of Ba in these fluids and the controls on barite (BaSO 4 ) precipitation and dissolution in oil and gas wells. Experiments simulating the acidizing stage evaluated the solubility of pure barite and drilling mud in 2 M HCl at 80 °C for periods of 2, 6, and 48 h and resulted in <0.01% barite dissolution with no appreciable change in δ 138 Ba ( 138 Ba/ 134 Ba normalized to NIST standard 3104a). Static autoclave experiments conducted at 66 °C and 20.7 MPa with combinations of ground Marcellus Shale solids and/or barite-bearing drilling mud with synthetic low-Ba fracturing fluid resulted in decreased Ba concentrations in the fluid, with the largest decrease in the shale-only run. Fluid δ 138 Ba values increased by about 0.5‰ as Ba concentrations decreased, consistent with closed-system Rayleigh fractionation. Flow-through experiments in Marcellus Shale core conducted for 28 days resulted in effluent Ba concentrations an order of magnitude lower than the influent, while sulfate concentrations increased over time. Effluent δ 138 Ba values increased over the first 12 days and plateaued at about 1‰ higher than the influent. Modeling suggests a combination of the release of labile shale Ba and barite precipitation. This work indicates that the processes of Ba release from fluid–shale interactions and barite precipitation in fractures and the well bore, while capable of producing high δ 138 Ba fluids, are unlikely to generate fluids with high-Ba concentrations and δ 138 Ba values like those in Marcellus-produced waters. As a result, we find that the release of sulfate from shale pyrite oxidation rapidly catalyzes barite precipitation and that dissolution of drilling mud barite or natural barite in the shale is unlikely to be the major source of Ba in Marcellus-produced waters.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Materials Data on Ba(HO)2 by Materials Project

Ba(OH)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 12-coordinate geometry to four H1+ and eight O2- atoms. There are a spread of Ba–H bond distances ranging from 2.68–2.83 Å. There are a spread of Ba–O bond distances ranging from 2.74–3.09 Å. In the second Ba2+ site, Ba2+ is bonded in a 3-coordinate geometry to four H1+ and seven O2- atoms. There are a spread of Ba–H bond distances ranging from 2.71–2.87 Å. There are a spread of Ba–O bond distances ranging from 2.76–2.93 Å. In the third Ba2+ site, Ba2+ is bonded in a 2-coordinate geometry to three H1+ and seven O2- atoms. There are a spread of Ba–H bond distances ranging from 2.74–2.99 Å. There are a spread of Ba–O bond distances ranging from 2.75–2.94 Å. In the fourth Ba2+ site, Ba2+ is bonded in a 9-coordinate geometry to two H1+ and seven O2- atoms. There are one shorter (2.77 Å) and one longer (2.93 Å) Ba–H bond lengths. There are a spread of Ba–O bond distances ranging from 2.79–3.10 Å. In the fifth Ba2+ site, Ba2+ is bonded in a 11-coordinate geometry to four H1+ and seven O2- atoms. There are a spread of Ba–H bond distances ranging from 2.57–2.89 Å. There are a spread of Ba–O bond distances ranging from 2.72–2.98 Å. In the sixth Ba2+ site, Ba2+ is bonded in a 12-coordinate geometry to five H1+ and seven O2- atoms. There are a spread of Ba–H bond distances ranging from 2.56–3.12 Å. There are a spread of Ba–O bond distances ranging from 2.61–2.89 Å. In the seventh Ba2+ site, Ba2+ is bonded in a 2-coordinate geometry to three H1+ and seven O2- atoms. There are a spread of Ba–H bond distances ranging from 2.68–2.88 Å. There are a spread of Ba–O bond distances ranging from 2.68–3.00 Å. In the eighth Ba2+ site, Ba2+ is bonded in a 5-coordinate geometry to five H1+ and seven O2- atoms. There are a spread of Ba–H bond distances ranging from 2.65–3.02 Å. There are a spread of Ba–O bond distances ranging from 2.68–3.11 Å. There are sixteen inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to two Ba2+ and one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to two Ba2+ and one O2- atom. The H–O bond length is 0.98 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to two Ba2+ and one O2- atom. The H–O bond length is 0.99 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to three Ba2+ and one O2- atom. The H–O bond length is 0.99 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to three Ba2+ and one O2- atom. The H–O bond length is 0.98 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to three Ba2+ and one O2- atom. The H–O bond length is 0.98 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to three Ba2+ and one O2- atom. The H–O bond length is 0.99 Å. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to three Ba2+ and one O2- atom. The H–O bond length is 0.99 Å. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to two Ba2+ and one O2- atom. The H–O bond length is 0.99 Å. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one Ba2+ and one O2- atom. The H–O bond length is 0.98 Å. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to two Ba2+ and one O2- atom. The H–O bond length is 0.98 Å. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to one Ba2+ and one O2- atom. The H–O bond length is 0.98 Å. In the fourteenth H1+ site, H1+ is bonded in a single-bond geometry to one Ba2+ and one O2- atom. The H–O bond length is 0.98 Å. In the fifteenth H1+ site, H1+ is bonded in a single-bond geometry to one Ba2+ and one O2- atom. The H–O bond length is 0.99 Å. In the sixteenth H1+ site, H1+ is bonded in a single-bond geometry to one Ba2+ and one O2- atom. The H–O bond length is 0.98 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to four Ba2+ and one H1+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to four Ba2+ and one H1+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to four Ba2+ and one H1+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to four Ba2+ and one H1+ atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to three Ba2+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to four Ba2+ and one H1+ atom. In the seventh O2- site, O2- is bonded in a single-bond geometry to four Ba2+ and one H1+ atom. In the eighth O2- site, O2- is bonded in a single-bond geometry to three Ba2+ and one H1+ atom. In the ninth O2- site, O2- is bonded in a single-bond geometry to three Ba2+ and one H1+ atom. In the tenth O2- site, O2- is bonded in a single-bond geometry to four Ba2+ and one H1+ atom. In the eleventh O2- site, O2- is bonded in a single-bond geometry to four Ba2+ and one H1+ atom. In the twelfth O2- site, O2- is bonded in a single-bond geometry to three Ba2+ and one H1+ atom. In the thirteenth O2- site, O2- is bonded in a single-bond geometry to three Ba2+ and one H1+ atom. In the fourteenth O2- site, O2- is bonded in a distorted single-bond geometry to three Ba2+ and one H1+ atom. In the fifteenth O2- site, O2- is bonded in a single-bond geometry to three Ba2+ and one H1+ atom. In the sixteenth O2- site, O2- is bonded in a single-bond geometry to four Ba2+ and one H1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(MgSn)2 by Materials Project

BaMg2Sn2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. there are two inequivalent Ba sites. In the first Ba site, Ba is bonded in a 12-coordinate geometry to eight Mg and eight Sn atoms. There are four shorter (3.75 Å) and four longer (3.98 Å) Ba–Mg bond lengths. There are four shorter (3.81 Å) and four longer (3.85 Å) Ba–Sn bond lengths. In the second Ba site, Ba is bonded in a 8-coordinate geometry to eight Mg and eight Sn atoms. There are four shorter (3.91 Å) and four longer (4.01 Å) Ba–Mg bond lengths. There are four shorter (3.76 Å) and four longer (3.82 Å) Ba–Sn bond lengths. There are three inequivalent Mg sites. In the first Mg site, Mg is bonded to four Ba and four Sn atoms to form MgBa4Sn4 tetrahedra that share corners with six equivalent MgBa4Sn4 tetrahedra, corners with six equivalent SnBa4Mg4 tetrahedra, an edgeedge with one SnBa4Mg4 tetrahedra, edges with five MgBa4Sn4 tetrahedra, and faces with four equivalent MgBa4Sn4 tetrahedra. There are two shorter (2.95 Å) and two longer (2.97 Å) Mg–Sn bond lengths. In the second Mg site, Mg is bonded to four equivalent Ba and four equivalent Sn atoms to form a mixture of edge, corner, and face-sharing MgBa4Sn4 tetrahedra. All Mg–Sn bond lengths are 2.95 Å. In the third Mg site, Mg is bonded in a 5-coordinate geometry to four equivalent Ba and five Sn atoms. There are one shorter (2.85 Å) and four longer (2.95 Å) Mg–Sn bond lengths. There are four inequivalent Sn sites. In the first Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent Ba and five Mg atoms. In the second Sn site, Sn is bonded to four equivalent Ba and four equivalent Mg atoms to form distorted SnBa4Mg4 tetrahedra that share corners with twelve equivalent MgBa4Sn4 tetrahedra, edges with two equivalent MgBa4Sn4 tetrahedra, edges with four equivalent SnBa4Mg4 tetrahedra, and faces with four equivalent SnBa4Mg4 tetrahedra. In the third Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent Ba, four equivalent Mg, and one Sn atom. The Sn–Sn bond length is 2.92 Å. In the fourth Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent Ba, four equivalent Mg, and one Sn atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(HO)2 by Materials Project

Ba(OH)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 2-coordinate geometry to four H1+ and seven O2- atoms. There are a spread of Ba–H bond distances ranging from 2.58–3.06 Å. There are a spread of Ba–O bond distances ranging from 2.67–3.05 Å. In the second Ba2+ site, Ba2+ is bonded in a 3-coordinate geometry to three O2- atoms. There are a spread of Ba–O bond distances ranging from 2.67–2.87 Å. In the third Ba2+ site, Ba2+ is bonded in a 5-coordinate geometry to six H1+ and eight O2- atoms. There are a spread of Ba–H bond distances ranging from 2.72–3.08 Å. There are a spread of Ba–O bond distances ranging from 2.76–3.12 Å. In the fourth Ba2+ site, Ba2+ is bonded in a 10-coordinate geometry to three H1+ and seven O2- atoms. There are a spread of Ba–H bond distances ranging from 2.60–2.87 Å. There are a spread of Ba–O bond distances ranging from 2.75–3.05 Å. In the fifth Ba2+ site, Ba2+ is bonded in a 8-coordinate geometry to six H1+ and six O2- atoms. There are a spread of Ba–H bond distances ranging from 2.54–2.96 Å. There are a spread of Ba–O bond distances ranging from 2.67–2.96 Å. In the sixth Ba2+ site, Ba2+ is bonded in a 10-coordinate geometry to three H1+ and seven O2- atoms. There are a spread of Ba–H bond distances ranging from 2.58–2.79 Å. There are a spread of Ba–O bond distances ranging from 2.75–2.87 Å. In the seventh Ba2+ site, Ba2+ is bonded in a 8-coordinate geometry to three H1+ and six O2- atoms. There are a spread of Ba–H bond distances ranging from 2.61–2.91 Å. There are a spread of Ba–O bond distances ranging from 2.62–2.86 Å. In the eighth Ba2+ site, Ba2+ is bonded in a 8-coordinate geometry to two H1+ and six O2- atoms. There are one shorter (2.53 Å) and one longer (2.71 Å) Ba–H bond lengths. There are a spread of Ba–O bond distances ranging from 2.65–2.91 Å. There are sixteen inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to two Ba2+ and one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one Ba2+ and one O2- atom. The H–O bond length is 1.00 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to three Ba2+ and one O2- atom. The H–O bond length is 0.99 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one Ba2+ and one O2- atom. The H–O bond length is 0.98 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to three Ba2+ and one O2- atom. The H–O bond length is 0.97 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to three Ba2+ and one O2- atom. The H–O bond length is 0.98 Å. In the seventh H1+ site, H1+ is bonded in a single-bond geometry to two Ba2+ and one O2- atom. The H–O bond length is 0.99 Å. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to two Ba2+ and one O2- atom. The H–O bond length is 1.01 Å. In the ninth H1+ site, H1+ is bonded in a single-bond geometry to two Ba2+ and one O2- atom. The H–O bond length is 0.98 Å. In the tenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the eleventh H1+ site, H1+ is bonded in a single-bond geometry to three Ba2+ and one O2- atom. The H–O bond length is 0.97 Å. In the twelfth H1+ site, H1+ is bonded in a single-bond geometry to two Ba2+ and one O2- atom. The H–O bond length is 0.98 Å. In the thirteenth H1+ site, H1+ is bonded in a single-bond geometry to two Ba2+ and one O2- atom. The H–O bond length is 0.98 Å. In the fourteenth H1+ site, H1+ is bonded in a single-bond geometry to one Ba2+ and one O2- atom. The H–O bond length is 0.98 Å. In the fifteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the sixteenth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to four Ba2+ and one H1+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to three Ba2+ and one H1+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to four Ba2+ and one H1+ atom. In the fourth O2- site, O2- is bonded in a single-bond geometry to three Ba2+ and one H1+ atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to two Ba2+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a single-bond geometry to two Ba2+ and one H1+ atom. In the seventh O2- site, O2- is bonded in a single-bond geometry to four Ba2+ and one H1+ atom. In the eighth O2- site, O2- is bonded in a single-bond geometry to four Ba2+ and one H1+ atom. In the ninth O2- site, O2- is bonded in a single-bond geometry to three Ba2+ and one H1+ atom. In the tenth O2- site, O2- is bonded in a single-bond geometry to two Ba2+ and one H1+ atom. In the eleventh O2- site, O2- is bonded in a single-bond geometry to two Ba2+ and one H1+ atom. In the twelfth O2- site, O2- is bonded in a single-bond geometry to three Ba2+ and one H1+ atom. In the thirteenth O2- site, O2- is bonded in a single-bond geometry to four Ba2+ and one H1+ atom. In the fourteenth O2- site, O2- is bonded in a single-bond geometry to four Ba2+ and one H1+ atom. In the fifteenth O2- site, O2- is bonded in a single-bond geometry to three Ba2+ and one H1+ atom. In the sixteenth O2- site, O2- is bonded in a single-bond geometry to three Ba2+ and one H1+ atom.

36 MATERIALS SCIENCE↗