scholarly journals NQR and Phase Transitions in Hexachlorocyclopropane Crystal

1990 ◽  
Vol 45 (3-4) ◽  
pp. 339-342 ◽  
Author(s):  
Masahiko Suhara ◽  
Koichi Mano
Keyword(s):  
Phase Transitions ◽  
Slow Rate ◽  
Metastable Phase ◽  
Phase Iii ◽  
Temperature Phase ◽  
Dsc Studies ◽  
Disordered Phase ◽  
Solid Phases ◽  
Low Temperature Phase ◽  
Phase Phase

Abstract35Cl NQR and DSC studies on phase transitions in hexachlorocyclopropane (HCCP), C3Cl6 , are reported. It is found that HCCP has three solid phases: A high temperature disordered phase (Phase I) above 301 K (no NQR spectrum was observed); a metastable phase (Phase II), which exhibited 6 NQR lines from 77 to 270 K; a low temperature phase (Phase III) in which a 24-multiplet of 35Cl NQR lines at 77 K, the most complex multiplet spectrum ever reported was observed. DSC measurement shows a A-type transition at 301 K and a broad transition of very slow rate at 285 K. The structure and mechanism of phase transitions in HCCP crystal are discussed.

Crystal Structure of Trimethylammonium Perchlorate in Three Solid Phases Including the Ionic Plastic Phase Obtainable above 480 K

1994 ◽  
Vol 49 (6) ◽  
pp. 723-726 ◽  
Author(s):  
Hiroyuki Ishida ◽  
Yoshihiro Kubozono ◽  
Setsuo Kashino ◽  
Ryuichi Ikeda
Keyword(s):  
Phase Iii ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Cscl Type ◽  
Thermal Measurements ◽  
Plastic Phase ◽  
Solid Phases ◽  
Phase Phase

Abstract The crystal structures of (CH3)3NHClO4 in three solid phases were studied by X-ray diffraction techniques. X-ray powder patterns taken at ca. 500 and 445 K revealed that the plastic phase (Phase I) attainable above 480 K crystallizes in a CsCl-type cubic structure with a = 5.845 (1) Å, Z = 1, V = 199.7 (2) Å3, and Dx = 1.327 g cm -3, while Phase II, stable between 480 and 396 K, forms a tetragonal structure with a = 9.912 (4), c = 7.01 (2) Å, Z = 4, V = 689 (3) Å3, and Dx = 1.54 gem -3. The room temperature phase (Phase III) was studied by single crystal X-ray diffraction and found to form a monoclinic lattice with space group P21 , a = 5.749(1), b = 8.670(1), c = 7.5585 (9) Å, ß = 102.66 (1)°, Z = 2, V = 367.6 (2) Å3 , and Dx= 1.441 g cm -3. Thermal measurements, differential thermal analysis and differential scanning calorimetry, were carried out on these solid phases, and the obtained results were compared with those observed for (CH3)3NHBF4.

Distortions of [Sb2Cl10]4– Bioctahedra and Phase Transitions in the Chloroantimonate(III) (C3H5NH3)2[SbCl5] · (C3H5NH3)Cl

2007 ◽  
Vol 62 (1) ◽  
pp. 44-50 ◽  
Author(s):  
Bartosz Zarychta ◽  
Maciej Bujak ◽  
Jacek Zaleski
Keyword(s):  
Crystal Structure ◽  
Phase Transitions ◽  
Low Temperature ◽  
Room Temperature ◽  
Lone Pair ◽  
Inorganic Salts ◽  
Organic Cations ◽  
Temperature Phase ◽  
Dsc Studies ◽  
Low Temperature Phase

Bis(allylammonium)pentachloroantimonate(III) - allylammonium chloride, (C3H5NH3)2[SbCl5] · (C3H5NH3)Cl, belongs to the chloroantimonate(III) organic-inorganic salts family. The DSC studies of this compound showed two anomalies at 181 K and at 223 K. Both are associated with phase transitions, which mainly occur due to ordering-disordering processes of the organic cations. Between 181 and 223 K the structure is incommensurate. The crystal structure was determined at 298 and 86 K. At both temperatures the crystal structure consists of (C3H5NH3)+ cations, anionic distorted [Sb2Cl10]4− units and isolated Cl− ions. In the room-temperature phase two out of three, and in the low-temperature phase two out of six allylammonium cations were found to be disordered. The deformations of the [Sb2Cl10]4− moieties in both phases are discussed and explained by the deviation of the SbIII 5s electron lone pair from its spherical symmetry and the influence of N-H···Cl hydrogen bonds, which join together the organic and inorganic sublattices.

Crystal Structure of Trimethylammonium Tetrafluoroborate in Three Solid Phases

2000 ◽  
Vol 55 (9-10) ◽  
pp. 765-768 ◽  
Author(s):  
Hiroyuki Ishida ◽  
Setsuo Kashino ◽  
Ryuichi Ikeda
Keyword(s):  
Crystal Structure ◽  
Phase Iii ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cscl Type ◽  
Lattice Space ◽  
Plastic Phase ◽  
Solid Phases ◽  
Phase Phase

Abstract The crystal structure of (CH3)3 NHBF 4 was studied in three solid phases by X-ray diffraction techniques. The structures of the ionic plastic phase (Phase I) stable above 453 K and Phase II between 384 and 453 K are CsCl-type cubic (a = 5.772(4) Å) and tetragonal (a = 9.815(5) and c = 6.895(5) Å), respectively. The room temperature phase (Phase III) forms a monoclinic lattice (space group P21/m, a = 5.7017(8), b = 8.5724(9), c = 7.444(1) Å, and ß = 102.76(1)°). BF4− ions in this phase were shown to be disordered in four orientations.

scholarly journals Fate of false vacua in holographic first-order phase transitions

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Francesco Bigazzi ◽  
Alessio Caddeo ◽  
Aldo L. Cotrone ◽  
Angel Paredes
Keyword(s):  
Phase Transitions ◽  
Chiral Symmetry ◽  
Metastable Phase ◽  
Chiral Symmetry Breaking ◽  
Model Parameters ◽  
Temperature Phase ◽  
Thin Wall ◽  
Critical Temperatures ◽  
First Order ◽  
First Order Phase

Abstract Using the holographic correspondence as a tool, we study the dynamics of first-order phase transitions in strongly coupled gauge theories at finite temperature. Considering an evolution from the large to the small temperature phase, we compute the nucleation rate of bubbles of true vacuum in the metastable phase. For this purpose, we find the relevant configurations (bounces) interpolating between the vacua and we compute the related effective actions. We start by revisiting the compact Randall-Sundrum model at high temperature. Using holographic renormalization, we compute the derivative term in the effective bounce action, that was missing in the literature. Then, we address the full problem within the top-down Witten-Sakai-Sugimoto model. It displays both a confinement/deconfinement and a chiral symmetry breaking/restoration phase transition which, depending on the model parameters, can happen at different critical temperatures. For the confinement/deconfinement case we perform the numerical analysis of an effective description of the transition and also provide analytic expressions using thick and thin wall approximations. For the chiral symmetry transition, we implement a variational approach that allows us to address the challenging non-linear problem stemming from the Dirac-Born-Infeld action.

X-ray study of the low-temperature phase transitions in LiKSO4

1983 ◽  
Vol 4 (1) ◽  
pp. 37-45 ◽  
Author(s):  
P. E. Tomaszewski ◽  
K. Łukaszewicz
Keyword(s):  
Phase Transitions ◽  
Low Temperature ◽  
Temperature Phase ◽  
X Ray ◽  
Low Temperature Phase

SHG Microscopic Studies on Low Temperature Phase Transitions of SrTi 16 O 3 and SrTi 18 O 3

2003 ◽  
Vol 285 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Yoshiaki Uesu ◽  
Ryuhei Nakai ◽  
Noritaka Kato ◽  
Carole Menoret ◽  
Jean-Michel Kiat ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Low Temperature ◽  
Temperature Phase ◽  
Microscopic Studies ◽  
Low Temperature Phase

Low-temperature phase transitions and dynamics of ammonium in (NH4)3H(SO4)2 and [(NH4)1−x Rbx]3H(SO4)2 crystals

2001 ◽  
Vol 43 (1) ◽  
pp. 117-126 ◽  
Author(s):  
L. S. Smirnov ◽  
A. I. Baranov ◽  
L. A. Shuvalov ◽  
L. Bobrowicz-Sarga ◽  
I. Natkaniec ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Low Temperature ◽  
Temperature Phase ◽  
Low Temperature Phase

Raman study of low temperature phase transitions in the cubic perovskite CH3NH3PbCI3

1998 ◽  
Vol 64 (4) ◽  
pp. 179-190 ◽  
Author(s):  
A. Maaej ◽  
M. Bahri ◽  
Y. Abid ◽  
N. Jaidane ◽  
Z. B. Lakhdar ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Low Temperature ◽  
Temperature Phase ◽  
Raman Study ◽  
Low Temperature Phase

Single-Crystal X-Ray Scattering Study of Superstructures and Phase Transitions in Graphite-Hno3 and Graphite-Br2 Intercalation Compounds

1982 ◽  
Vol 20 ◽  
Author(s):  
R. Moret ◽  
R. Comes ◽  
G. Furdin ◽  
H. Fuzellier ◽  
F. Rousseaux
Keyword(s):  
Phase Transitions ◽  
Low Temperature ◽  
Room Temperature ◽  
Temperature Phase ◽  
Temperature Structure ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Temperature Liquid ◽  
Low Temperature Phase

ABSTRACTIn α-C5n-HNO3 the condensation of the room-temperature liquid-like diffuse ring associated with the disorder-order transition around 250 K is studied and the low-temperature. superstructure is examined.It is found that β-C8n-HNO3 exhibits an in-plane incommensurate order at room temperature.Two types of graphite-Br2 are found. Low-temperature phase transitions in C8Br are observed at T1 ≍ 277 K and T2 ≍ 297 K. The room-temperature structure of C14Br is reexamined. Special attention is given to diffuse scattering and incommensurability.

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