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At least 19 records

Materials Data on B(HO)2 by Materials Project

B(OH)2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of eight dihydroxyboron molecules. B is bonded in a bent 120 degrees geometry to two O atoms. There is one shorter (1.37 Å) and one longer (1.38 Å) B–O bond length. There are two 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 0.97 Å. In the second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.97 Å. There are two inequivalent O sites. In the first O site, O is bonded in a water-like geometry to one B and one H atom. In the second O site, O is bonded in a bent 120 degrees geometry to one B and one H atom.

36 MATERIALS SCIENCE↗

Materials Data on Ho2(Ni2B)5 by Materials Project

Ho2(Ni2B)5 crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. there are two inequivalent Ho sites. In the first Ho site, Ho is bonded in a 7-coordinate geometry to fifteen Ni and three B atoms. There are a spread of Ho–Ni bond distances ranging from 2.75–3.33 Å. There are a spread of Ho–B bond distances ranging from 2.72–2.85 Å. In the second Ho site, Ho is bonded in a 2-coordinate geometry to fourteen Ni and five B atoms. There are a spread of Ho–Ni bond distances ranging from 2.78–3.16 Å. There are a spread of Ho–B bond distances ranging from 2.71–3.05 Å. There are ten inequivalent Ni sites. In the first Ni site, Ni is bonded in a 4-coordinate geometry to three Ho and four B atoms. There are a spread of Ni–B bond distances ranging from 2.06–2.10 Å. In the second Ni site, Ni is bonded in a 4-coordinate geometry to two Ho and three B atoms. There are two shorter (2.06 Å) and one longer (2.10 Å) Ni–B bond lengths. In the third Ni site, Ni is bonded in a 3-coordinate geometry to three equivalent Ho and three B atoms. There are a spread of Ni–B bond distances ranging from 1.92–2.19 Å. In the fourth Ni site, Ni is bonded in a 12-coordinate geometry to three Ho and three B atoms. There are two shorter (2.03 Å) and one longer (2.06 Å) Ni–B bond lengths. In the fifth Ni site, Ni is bonded in a 2-coordinate geometry to three Ho and three B atoms. There are a spread of Ni–B bond distances ranging from 2.03–2.13 Å. In the sixth Ni site, Ni is bonded in a 1-coordinate geometry to three equivalent Ho and two B atoms. There are one shorter (2.02 Å) and one longer (2.22 Å) Ni–B bond lengths. In the seventh Ni site, Ni is bonded in a 2-coordinate geometry to four Ho and three B atoms. There are a spread of Ni–B bond distances ranging from 2.05–2.13 Å. In the eighth Ni site, Ni is bonded in a 3-coordinate geometry to three equivalent Ho and three B atoms. There are a spread of Ni–B bond distances ranging from 1.97–2.06 Å. In the ninth Ni site, Ni is bonded in a 3-coordinate geometry to three equivalent Ho and three B atoms. There are a spread of Ni–B bond distances ranging from 2.02–2.09 Å. In the tenth Ni site, Ni is bonded in a 4-coordinate geometry to two Ho and four B atoms. There are a spread of Ni–B bond distances ranging from 2.05–2.13 Å. There are five inequivalent B sites. In the first B site, B is bonded in a 9-coordinate geometry to two equivalent Ho, six Ni, and one B atom. The B–B bond length is 1.91 Å. In the second B site, B is bonded in a 7-coordinate geometry to two equivalent Ho, six Ni, and one B atom. The B–B bond length is 1.72 Å. In the third B site, B is bonded in a 7-coordinate geometry to one Ho and seven Ni atoms. In the fourth B site, B is bonded in a 9-coordinate geometry to two equivalent Ho, six Ni, and one B atom. In the fifth B site, B is bonded in a 8-coordinate geometry to one Ho, six Ni, and one B atom.

36 MATERIALS SCIENCE↗

Materials Data on Ho(BC)2 by Materials Project

HoB2C2 crystallizes in the tetragonal P4_2/mmc space group. The structure is three-dimensional. Ho is bonded in a 8-coordinate geometry to eight equivalent B and eight equivalent C atoms. All Ho–B bond lengths are 2.73 Å. All Ho–C bond lengths are 2.70 Å. B is bonded in a 2-coordinate geometry to four equivalent Ho and two equivalent C atoms. Both B–C bond lengths are 1.60 Å. C is bonded in a 2-coordinate geometry to four equivalent Ho, two equivalent B, and one C atom. The C–C bond length is 1.42 Å.

36 MATERIALS SCIENCE↗

Materials Data on Ho(BO2)6 by Materials Project

Ho(BO2)6 crystallizes in the trigonal R3c space group. The structure is three-dimensional. Ho is bonded in a 9-coordinate geometry to nine O atoms. There are a spread of Ho–O bond distances ranging from 2.34–2.47 Å. There are two 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 1.45–1.51 Å. In the second B site, B is bonded in a trigonal planar geometry to three O atoms. There are a spread of B–O bond distances ranging from 1.36–1.39 Å. There are four inequivalent O sites. In the first O site, O is bonded in a distorted bent 120 degrees geometry to one Ho and one B atom. In the second O site, O is bonded in a 2-coordinate geometry to one Ho and two B atoms. In the third O site, O is bonded in a distorted bent 120 degrees geometry to one Ho and two B atoms. In the fourth O site, O is bonded in a bent 120 degrees geometry to two B atoms.

36 MATERIALS SCIENCE↗

Materials Data on CaB2(HO)8 by Materials Project

Ca(B(OH)4)2 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one Ca(B(OH)4)2 sheet oriented in the (0, 1, 1) direction. Ca2+ is bonded in a 9-coordinate geometry to one H1+ and eight O2- atoms. The Ca–H bond length is 2.61 Å. There are a spread of Ca–O bond distances ranging from 2.39–2.70 Å. There are two inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of B–O bond distances ranging from 1.48–1.51 Å. In the second B3+ site, B3+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of B–O bond distances ranging from 1.47–1.52 Å. There are eight inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the second 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 third 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 fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the fifth 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 sixth 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 seventh H1+ site, H1+ is bonded in a single-bond geometry to one Ca2+ and one O2- atom. The H–O bond length is 0.98 Å. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to one Ca2+, one B3+, and one H1+ atom. In the second O2- site, O2- is bonded in a distorted water-like geometry to one Ca2+, one B3+, and one H1+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one B3+, and one H1+ atom. In the fourth O2- site, O2- is bonded in a distorted water-like geometry to one Ca2+, one B3+, and one H1+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ca2+, one B3+, and one H1+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one B3+, and one H1+ atom. In the seventh O2- site, O2- is bonded in a distorted water-like geometry to one Ca2+, one B3+, and one H1+ atom. In the eighth O2- site, O2- is bonded in a distorted water-like geometry to one B3+ and one H1+ atom.

36 MATERIALS SCIENCE↗

Materials Data on CaB2(HO)8 by Materials Project

Ca(B(OH)4)2 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one Ca(B(OH)4)2 sheet oriented in the (0, 1, 1) direction. Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.39–2.65 Å. There are two inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of B–O bond distances ranging from 1.48–1.50 Å. In the second B3+ site, B3+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of B–O bond distances ranging from 1.48–1.51 Å. There are eight inequivalent H1+ sites. In the first 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 second 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 third 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 fourth 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 fifth 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 sixth 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 seventh H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.97 Å. In the eighth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to one Ca2+, one B3+, and one H1+ atom. In the second O2- site, O2- is bonded in a distorted water-like geometry to one Ca2+, one B3+, and one H1+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one B3+, and one H1+ atom. In the fourth O2- site, O2- is bonded in a distorted water-like geometry to one Ca2+, one B3+, and one H1+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ca2+, one B3+, and one H1+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one Ca2+, one B3+, and one H1+ atom. In the seventh O2- site, O2- is bonded in a distorted water-like geometry to one Ca2+, one B3+, and one H1+ atom. In the eighth O2- site, O2- is bonded in a distorted water-like geometry to one B3+ and one H1+ atom.

36 MATERIALS SCIENCE↗

Tuning the melting point and phase stability of rare-earth oxides to facilitate their crystal growth from the melt

The challenge of growing rare-earth (RE) sesquioxide crystals can be overcome by tailoring their structural stability and melting point via composition engineering. This work contributes to the advancement of the field of crystal growth of high-entropy oxides. A compound with only small REs (Lu,Y,Ho,Yb,Er) 2 O 3 maintains a cubic C-type structure upon cooling from the melt, as observed via in-situ high-temperature neutron diffraction on aerodynamically levitated samples. On the other hand, a compound with a mixture of small and large REs (Lu,Y,Ho,Nd,La) 2 O 3 crystallizes as a mixture of a primary C-type phase with an unstable secondary phase. Crystals of compositions (Lu,Y,Ho,Nd,La) 2 O 3 and (Lu,Y,Gd,Nd,La) 2 O 3 were grown by the micro-pulling-down (mPD) method with a single monoclinic B-type phase, while a powder of (Lu,Y,Ho,Yb,Er) 2 O 3 did not melt at the maximum operating temperature of an iridium-rhenium crucible. The minimization of the melting point of the two grown crystals is attributed to the mismatch in cation sizes. The electron probe microanalysis reveals that the general element segregation behavior in the crystals depends on the composition.

36 MATERIALS SCIENCE↗

Materials Data on Ho2B4C by Materials Project

Ho2B4C crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Ho is bonded in a 2-coordinate geometry to six equivalent B and two equivalent C atoms. There are four shorter (2.72 Å) and two longer (2.97 Å) Ho–B bond lengths. Both Ho–C bond lengths are 2.40 Å. There are two inequivalent B sites. In the first B site, B is bonded in a 3-coordinate geometry to six equivalent Ho and three B atoms. There is one shorter (1.77 Å) and two longer (1.87 Å) B–B bond length. In the second B site, B is bonded in a distorted single-bond geometry to two equivalent B and one C atom. The B–C bond length is 1.50 Å. C is bonded to four equivalent Ho and two equivalent B atoms to form distorted edge-sharing CHo4B2 octahedra.

36 MATERIALS SCIENCE↗

Materials Data on Ho(BC)2 by Materials Project

HoB2C2 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Ho is bonded in a 8-coordinate geometry to eight equivalent B and eight equivalent C atoms. All Ho–B bond lengths are 2.73 Å. All Ho–C bond lengths are 2.67 Å. B is bonded in a distorted trigonal planar geometry to four equivalent Ho and three equivalent C atoms. There is one shorter (1.52 Å) and two longer (1.60 Å) B–C bond length. C is bonded in a 3-coordinate geometry to four equivalent Ho and three equivalent B atoms.

36 MATERIALS SCIENCE↗

Materials Data on Ho(CoB)2 by Materials Project

HoCo2B2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ho3+ is bonded in a body-centered cubic geometry to eight equivalent B3- atoms. All Ho–B bond lengths are 2.87 Å. Co+1.50+ is bonded to four equivalent B3- atoms to form a mixture of edge and corner-sharing CoB4 tetrahedra. All Co–B bond lengths are 2.01 Å. B3- is bonded in a 4-coordinate geometry to four equivalent Ho3+ and four equivalent Co+1.50+ atoms.

36 MATERIALS SCIENCE↗

Chemical kinetic interactions of NO with a multi-component gasoline surrogate: Experiments and modeling

Here this work reports an experimental and modeling study on the chemical kinetic interactions of NO with a multi-component gasoline surrogate, namely PACE-20, using a twin-piston rapid compression machine at a stochiometric fuel loading with 20% EGR (exhaust gas recirculation) by mass, pressures of 20 and 40 bar, and temperatures from 700 to 930 K. Five NO concentrations are investigated, namely 0, 20, 50, 70 and 150 ppm, where NO addition effects are characterized through changes in PACE-20 ignition reactivity and heat release characteristics. Experiments indicate that within the low-temperature regime, NO promotes low-temperature heat release rate and main ignition reactivity at low addition levels, with saturation or even inhibiting effects observed at >50 ppm NO addition, while within the NTC/intermediate-temperature regime, adding NO only promotes reactivity. A recently updated, detailed chemical kinetic model with chemistry specific to NOx/hydrocarbons interaction incorporated is used to simulate the experiments, and reasonable agreement is obtained. In-depth sensitivity and rate of production analyses are further performed. The results indicate that NO interacts with PACE-20 via two types of interaction: (a) direct interactions between NO and PACE-20 derivatives, primarily through NO+HO 2 ↔NO 2 +OH and RO 2 +NO↔RO+NO 2 , and (b) indirect interactions between PACE-20 derivatives and NO 2 produced from the direct interactions, primarily through R+NO 2 ↔RO+NO. The observed NO inhibiting effect at low temperatures and 150 ppm NO addition is attributed to the lack of HO 2 radicals to sustain NO consumption via NO+HO 2 ↔NO 2 +OH, and the take-up of inhibiting pathways via RO 2 +NO↔RO+NO 2 . The results also indicate that even with the presence of multiple fuel components, NOx/hydrocarbons interactions are highly selective, and are mainly initiated by the interactions between NO and RO 2 radicals from cyclopentane and ethanol, as well as between NO 2 and R radicals from toluene, 1,2,4-trimethylbenzene and 1-hexene. Further studies on these interactive reactions are therefore highly recommended.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Materials Data on Ho(FeB)2 by Materials Project

Ho(FeB)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ho is bonded in a 8-coordinate geometry to eight equivalent Fe and eight equivalent B atoms. All Ho–Fe bond lengths are 2.94 Å. All Ho–B bond lengths are 2.94 Å. Fe is bonded in a 4-coordinate geometry to four equivalent Ho and four equivalent B atoms. All Fe–B bond lengths are 2.00 Å. B is bonded in a 4-coordinate geometry to four equivalent Ho and four equivalent Fe atoms.

36 MATERIALS SCIENCE↗

Materials Data on B(HO)3 by Materials Project

H3BO3 is alpha Selenium structured and crystallizes in the trigonal P3_2 space group. The structure is zero-dimensional and consists of three H3BO3 clusters. there are two inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. All B–O bond lengths are 1.38 Å. In the second B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. All B–O bond lengths are 1.38 Å. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.67 Å) H–O bond length. In the second H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the third H1+ site, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.67 Å) H–O bond length. In the fourth H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the fifth H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the sixth H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one B3+ and two H1+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one B3+ and one H1+ atom. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one B3+ and one H1+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one B3+ and two H1+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one B3+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one B3+ and one H1+ atom.

36 MATERIALS SCIENCE↗

Crystal and magnetic structure of polar oxide HoCrWO 6

In this study, polar magnetic oxide HoCrWO 6 is synthesized and its crystal structure, magnetic structure, and thermodynamic properties are investigated. HoCrWO 6 forms the polar crystal structure (space group Pna 2 1 (#33)) due to the cation ordering of W 6+ and Cr 3+ . There is an antiferromagnetic transition at T N = 24.5 K along with the magnetic entropy change (~5 J.Kg. –1 K –1 at 70 kOe). Neutron diffraction measurement indicates that both Cr and Ho sublattices are ordered with the moment of 2.32(5)μ B and 8.7(4)μ B at 2 K, respectively. While Cr forms A-type collinear antiferromagnetic (AFM) structure with magnetic moment along the b axis, Ho sublattice orders in a non-coplanar AFM arrangement. A comparison with isostructural DyFeWO 6 and DyCrWO 6 indicates that the magnetic structure of this family of compounds is controlled by the presence or absence of e g electrons in the transition metal sublattice.

42 ENGINEERING↗

Materials Data on Ho(NiB)2 by Materials Project

Ho(NiB)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Ho3+ is bonded in a 6-coordinate geometry to six equivalent B3- atoms. There are a spread of Ho–B bond distances ranging from 2.69–2.88 Å. Ni+1.50+ is bonded in a 4-coordinate geometry to four equivalent B3- atoms. There are a spread of Ni–B bond distances ranging from 2.02–2.07 Å. B3- is bonded in a 8-coordinate geometry to three equivalent Ho3+, four equivalent Ni+1.50+, and one B3- atom. The B–B bond length is 1.74 Å.

36 MATERIALS SCIENCE↗

Materials Data on Ho5(SiB4)2 by Materials Project

Ho5Si2B8 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. there are two inequivalent Ho sites. In the first Ho site, Ho is bonded in a 12-coordinate geometry to nine B and three equivalent Si atoms. There are a spread of Ho–B bond distances ranging from 2.62–2.95 Å. There are one shorter (3.04 Å) and two longer (3.11 Å) Ho–Si bond lengths. In the second Ho site, Ho is bonded to two equivalent B and four equivalent Si atoms to form corner-sharing HoSi4B2 octahedra. The corner-sharing octahedral tilt angles are 57°. Both Ho–B bond lengths are 2.71 Å. All Ho–Si bond lengths are 2.89 Å. There are three inequivalent B sites. In the first B site, B is bonded in a 9-coordinate geometry to four equivalent Ho and five B atoms. There are a spread of B–B bond distances ranging from 1.75–1.83 Å. In the second B site, B is bonded in a 3-coordinate geometry to six equivalent Ho and three B atoms. The B–B bond length is 1.83 Å. In the third B site, B is bonded in a 9-coordinate geometry to five Ho and four equivalent B atoms. Si is bonded in a 9-coordinate geometry to eight Ho and one Si atom. The Si–Si bond length is 2.35 Å.

36 MATERIALS SCIENCE↗

Measurement of atmospheric HO by a chemical method

The parameters for a chemical technique can be outlined from the following set of desirable goals: (1) sufficient conversion of tracer species A to product B that B can be measured quantitatively in the presence of A and a great excess of air; (2) specificity of reaction such that A is converted to B only by reaction with HO; and (3) sufficient sensitivity for detection that the ambient concentration of HO is not seriously perturbed by the presence of A and B. This proposed study involves finding a chemical reaction specific enough for OH, and a measurement of the product formed. What one wants is a rate constant of about 10 to the -10th power cu cm/s, so that 0.1 percent of the OH will be converted in 100 s. Laboratory studies are needed to find a reaction which will fill this bill, yielding a product in quantity sufficient for precise measurement. This is an extremely fast constant and the search may be difficult. Again there is a question of perturbing the local environment, while still providing a sensitive measurement. Also the temperature and pressure dependence of the reaction rate is a complicated function for many of these species (that is, one must use a RRKM or Troe-based picture), and must be taken into account.

Iyer, R. Subramonia↗