scholarly journals The use of vibrating wire technique for precise positioning of CESR Phase III super-conducting quadrupoles at room temperature

2002 ◽  
Author(s):  
A. Temnykh
Keyword(s):  
Room Temperature ◽  
Phase Iii ◽  
Vibrating Wire ◽  
Precise Positioning ◽  
Super Conducting

Amorphous Blue Phase III Exhibiting Submillisecond Response and Hysteresis-Free Switching at Room Temperature

2011 ◽  
Vol 4 (10) ◽  
pp. 101701 ◽  
Author(s):  
Atsushi Yoshizawa ◽  
Michi Kamiyama ◽  
Tetsu Hirose
Keyword(s):  
Room Temperature ◽  
Phase Iii ◽  
Blue Phase

Using Self-assembly and Selective Chemical Vapor Deposition for Precise Positioning of Individual Germanium Nanoparticles on Hafnia

2006 ◽  
Vol 921 ◽  
Author(s):  
Shawn S Coffee ◽  
Wyatt A Winkenwerder ◽  
Scott K Stanley ◽  
Shahrjerdi Davood ◽  
Sanjay K Banerjee ◽  
...  
Keyword(s):  
Thin Film ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Self Assembly ◽  
Room Temperature ◽  
Chemical Vapor ◽  
Pore Density ◽  
Hot Wire ◽  
Precise Positioning ◽  
Selective Chemical

AbstractGermanium nanoparticle nucleation was studied in organized arrays on HfO2 using a SiO2 thin film mask with ~20-24 nm pores and a 6×1010 cm-2 pore density. Poly(styrene-b-methyl methacrylate) diblock copolymer was employed to pattern the SiO2 film. Hot wire chemical vapor deposition produced Ge nanoparticles using 4-19 monolayer Ge exposures. By seeding adatoms on HfO2 at room temperature before growth and varying growth temperatures between 725-800 K, nanoparticle size was demonstrated to be limited by Ge etching of SiO2 pore walls.

Structure and Bonding of Tribromocadmates, ACdBr3, A = NH4, Rb, Cs, CH3NH3, (CH3)2NH2, (CH3)4N], [H2NNH3, and (H2N)3C. An X-ray Diffraction and 79-81Br NQR Study

1991 ◽  
Vol 46 (12) ◽  
pp. 1063-1082 ◽  
Author(s):  
V. G. Krishnan ◽  
Shi-qi Dou ◽  
Alarich Weiss
Keyword(s):  
Room Temperature ◽  
High Temperature Phase ◽  
Phase Iii ◽  
Line Spectrum ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Single Chain ◽  
Double Chain ◽  
81Br Nqr ◽  
A Chain

Abstract The 79-81Br NQR spectra of tribromocadmates with the cations K⊕, NH4⊕, Rb⊕, Cs⊕, CH3NH3⊕, (CH3)2NH2⊕, (CH3)4N⊕, H2NNH3⊕, and C(NH2)3⊕ were studied as functions of temperature from 77 K on up to T>300 K. CsCdBr3 shows a singlet 81Br NQR spectrum over the whole temperature range studied. [CH3NH3]CdBr3, with one 81Br NQR line spectrum at room temperature, experiences a phase transition at 167 K; below this temperature an 18-line spectrum is observed. In [(CH3)4N]CdBr3 (phase II), at 290 K, a singlet 81Br NQR is present as is in the high temperature phase III (TII.1 , = 390 K); the low temperature phase III (TII,m, = 160 K has a triplet 81Br NQR spectrum. KCdBr3 shows an 81Br NQR doublet spectrum, as do RbCdBr3, [H2NNH3]CdBr3, and [C(NH2)3]CdBr3. 81Br NQR triplets are observed for [(CH3)2NH2]CdBr3 and NH4CdBr3. Several crystal structures were determined (at room temperature). [(CH3)4N]CdBr3: P63/m, Z = 2, a - 940 pm, c = 700 pm, disordered cation, single chain Perovskite with face connected [CdBr6]- octahedra (nearly CsNiCl3-type). [(CH3)2NH2]CdBr3: P21/c, Z = 4, a = 898 pm, 6 = 1377 pm, c = 698 pm, ß = 91.2°, face connected [CdBr3-octahedra single chain Perovskite. NH4CdBr3: Pnma, Z = 4, a = 950 pm, b = 417 pm, c= 1557 pm, with a double chain of condensed [CdBr6]-octahedra, NH4CdCl3-type. [N2H5]CdBr3: P2,/c, Z = 4, a = 395 pm, 6 = 1749 pm,c = 997 pm,ß = 94.2°, double chain polyanion similar to NH4CdBr3. [C(NH2)3]CdBr3: C2/c, Z = 4, a = 778 pm, 6 = 1598 pm, c = 746 pm, ß = 110.2°, a single chain Perovskite with a chain of condensed trigonal bipyramids [CdBr5]. Three types of anion chains of CdBr3 have been observed: Single octahedral chains, face connected; double octahedral chains, edge connected; a trigonal-bipyramidal chain, edge connected. The relation between the crystal structure and the Br NQR is discussed

[Ni(MeCN)(H2O)2(NO3)2]·(15-crown-5)·MeCN: detailed study of a four-phase sequence that includes an intermediate modulated phase

2012 ◽  
Vol 68 (4) ◽  
pp. 389-400 ◽  
Author(s):  
Maxime A. Siegler ◽  
Sean Parkin ◽  
Carolyn Pratt Brock
Keyword(s):  
Phase I ◽  
Phase Ii ◽  
Room Temperature ◽  
Reciprocal Lattice ◽  
Phase Iii ◽  
Stability Range ◽  
Acta Cryst ◽  
Disordered Phase ◽  
Phase Sequence ◽  
Modulated Phase

A sequence of four phases has been found for an acetonitrile-solvated co-crystal with 15-crown-5 of the nickel complex [acetonitrilediaqua-κ1 O-nitrato-κ2 O-nitratonickel(II)]. The structure could be determined at intervals of ca 10 K in the range 90–273 K because crystals remain single through the three transitions. In phase (I) (T ≥ ca 240 K; P21/m, Z′ = ½), there is extensive disorder, which is mostly resolved in phase (III) (ca 230–145 K; P21/c, Z′ = 1). Phase (IV) (ca 145–90 K, and probably below; P\overline 1, Z′ = 2) is ordered. Phase (II) (ca 238–232 K) is modulated, but the satellite reflections are too weak to allow the structure to be determined within its stability range by standard methods. Most crystals that were flash-cooled from room temperature to 90 K have a metastable P21, Z′ = 5 superstructure that (at least in a commensurate approximation) was identified as similar to the structure of phase (II) by comparison of reconstructed reciprocal-lattice slices and by analogy with the phase behavior of the very similar compound [Ni(H2O)6](NO3)2·(15-crown-5)·2H2O [Siegler et al. (2011). Acta Cryst. B67, 486–498]. In the phase (II) structure slab-like regions that are like the disordered phase (I) structure alternate with regions of similar shape and size that are like the more ordered phase (III) structure.

The crystal structure of high-pressure americium, phase III

1981 ◽  
Vol 14 (6) ◽  
pp. 447-450 ◽  
Author(s):  
R. B. Roof
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Least Squares ◽  
Pressure Range ◽  
Room Temperature ◽  
Nearest Neighbors ◽  
Phase Iii ◽  
Intensity Data ◽  
Monoclinic Lattice ◽  
Layer Stacking

The structure of high-pressure americium, phase III, which occurs at room temperature in the pressure range 10–15 GPa, has been determined. The material has a monoclinic lattice with a = 3.025±0.005, b = 11.887±0.019, c = 2.830±0.005 Å, and β = 106.11±0.14° at 12.5 GPa. The space group is P21/m with Z = 4. Intensity data were obtained from powder-pattern films taken at pressure with Mo Kα radiation, λ = 0.7107 Å. The structure, which can be described as a layer stacking intermediate between the lower-pressure f.c.c. and higher-pressure α-U structure types, was refined by least-squares calculations to R 1 = 0.07 with 12 observed reflections. Am–Am distances of nearest neighbors range from 2.83 to 3.21 Å.

Low-temperature phases of dicalcium barium hexakis(propanoate)

2021 ◽  
Vol 77 (11) ◽  
Author(s):  
Jan Fábry ◽  
Michal Dušek
Keyword(s):  
Low Temperature ◽  
Phase I ◽  
Room Temperature ◽  
High Temperature Phase ◽  
The Other ◽  
Phase Iii ◽  
Temperature Phase ◽  
Acta Cryst ◽  
Carboxylate Groups ◽  
Structure Determinations

The structure determinations of phases (II) and (III) of barium dicalcium hexakis(propanoate) {or poly[hexa-μ4-propanoato-bariumdicalcium], [BaCa2(C3H5O2)6] n } are reported at 240 and 130 K, respectively [phase (I) was determined previously by Stadnicka & Glazer (1980). Acta Cryst. B36, 2977–2985; our structure determination of phase (I) at room temperature is included in the supporting information]. In the high-temperature phase, the Ba2+ cation is surrounded by six carboxylate groups in bidentate bridging modes. In the low-temperature phases, five carboxylate groups act in bidentate bridging modes and one acts in a monodentate bridging mode around Ba2+. The Ca2+ cations are surrounded by six carboxylate O atoms in a trigonal antiprism in all the structures. The Ba2+ and Ca2+ cations are underbonded and significantly overbonded, respectively, in all the phases. The bonding of the Ba2+ cation increases slightly at the cost of the bonding of Ca2+ cations during cooling to the low-temperature phases. The phase transitions during cooling are accompanied by ordering of the ethyl chains. In room-temperature phase (I), all six ethyl chains are positionally disordered over two positions in the crossed mode, with additional splitting of the ethyl α- and β-C atoms. In phase (II), on the other hand, there are three disordered ethyl chains, one with positionally disordered ethyl α- and β-C atoms, and the other two with positionally disordered ethyl β-C atoms only, and in the lowest-temperature phase (III) there are four ordered ethyl chains and two disordered ethyl chains with positionally disordered ethyl β-C atoms only.

High-temperature phase transitions and domain structures of KLiSO4: studied by polarisation-optics, X-ray topography and liquid–crystal surface decoration

2017 ◽  
Vol 232 (6) ◽  
Author(s):  
Christian Scherf ◽  
Nicolay R. Ivanov ◽  
Su Jin Chung ◽  
Theo Hahn ◽  
Helmut Klapper
Keyword(s):  
Liquid Crystal ◽  
High Temperature ◽  
Room Temperature ◽  
Crystal Surface ◽  
High Temperature Phase ◽  
Phase Iii ◽  
Temperature Phase ◽  
X Ray ◽  
Domain Structures ◽  
Surface Decoration

AbstractThe transitions between the room temperature phase III (space group

scholarly journals Structure of methane and ethane at high pressure

2014 ◽  
Vol 70 (a1) ◽  
pp. C757-C757 ◽  
Author(s):  
Alexander Goncharov ◽  
Elissaios Stavrou ◽  
Sergey Lobanov ◽  
Artem Oganov ◽  
Valery Roisen ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Relative Stability ◽  
Room Temperature ◽  
High Pressures ◽  
Equations Of State ◽  
Theoretical Calculations ◽  
Chemical Reactivity ◽  
Phase Iii ◽  
X Ray Diffraction ◽  
Theoretical Predictions

Methane is one of the most abundant hydrocarbon molecules in the universe and is expected to be a significant part of the icy giant planets (Uranus and Neptune) and their satellites. Ethane is one of the most predictable products of chemical reactivity of methane at extreme pressures and temperatures. In spite of numerous experimental and theoretical studies, the structure and relative stability of these materials even at room temperature remains controversial. We have performed a combined experimental and theoretical study of both methane and ethane up at high pressures up to 120 GPa at 300 K using x-ray diffraction and Raman spectroscopy and the ab-initio evolutionary algorithm, respectively. In the case of methane we have successfully solved the structure of phase B by determining the space group and the positional parameters of carbon atoms, and by completing these results for the hydrogen positions using the theoretical calculations. The general structural behavior under pressure and the relation between phase B and phases A and pre-B will be also discussed. For ethane we have determined the crystallization point, for room temperature, at 1.7 GPa and also the low pressure crystal structure (Phase A). This crystal structure is orientationally disordered (plastic phase) and deviates from the known crystal structures for ethane at low temperatures. Moreover, a pressure induced phase transition has been indentified, for the first time, at 18 GPa to a monoclinic phase III, the structure of which is solved based on a good agreement of the experimental results and theoretical predictions. We have determined the equations of state of methane and ethane, which provides a solid basis for the discussion of their relative stability at high pressures.

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