scholarly journals Ordering Phase Transition with Symmetry-Breaking from Disorder over Non-Equivalent Sites: Calorimetric and Crystallographic Study of Crystalline d-Sorbose

Crystals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 361
Author(s):  
Sakiko Iwagaki ◽  
Hiroki Kakuta ◽  
Yasuhisa Yamamura ◽  
Hideki Saitoh ◽  
Mafumi Hishida ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Phase Transitions ◽  
Structural Disorder ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Apparent Contradiction ◽  
X Ray ◽  
Thermal Anomalies ◽  
X Ray Crystallography ◽  
Main Transition

Phase transitions in the crystalline state of chiral sorbose were examined using precise heat capacity calorimetry and X-ray crystallography. The calorimetry established heat capacity below room temperature. Besides the known transition (main transition) at 199.5 K, the calorimetry detected plural thermal anomalies assignable to new phase transitions (around 210 K) and a glass transition (at ca. 120 K). The X-ray diffraction at low temperatures established the crystal structure of the lowest temperature phase. The identification of the broken symmetry upon the main transition solves an apparent contradiction that the structural disorder reported previously does not contribute seemingly to the symmetrization.

The structures and phase transitions in 4-aminopyridinium tetraaquabis(sulfato)iron(III), (C5H7N2)[FeIII(H2O)4(SO4)2]

2019 ◽  
Vol 75 (6) ◽  
pp. 1144-1151
Author(s):  
Tamara J. Bednarchuk ◽  
Wolfgang Hornfeck ◽  
Vasyl Kinzhybalo ◽  
Zhengyang Zhou ◽  
Michal Dušek ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Single Crystal ◽  
Room Temperature ◽  
Variable Temperature ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Hybrid Compound ◽  
Space Group ◽  
X Ray

The organic–inorganic hybrid compound 4-aminopyridinium tetraaquabis(sulfato)iron(III), (C5H7N2)[FeIII(H2O)4(SO4)2] (4apFeS), was obtained by slow evaporation of the solvent at room temperature and characterized by single-crystal X-ray diffraction in the temperature range from 290 to 80 K. Differential scanning calorimetry revealed that the title compound undergoes a sequence of three reversible phase transitions, which has been verified by variable-temperature X-ray diffraction analysis during cooling–heating cycles over the temperature ranges 290–100–290 K. In the room-temperature phase (I), space group C2/c, oxygen atoms from the closest Fe-atom environment (octahedral) were disordered over two equivalent positions around a twofold axis. Two intermediate phases (II), (III) were solved and refined as incommensurately modulated structures, employing the superspace formalism applied to single-crystal X-ray diffraction data. Both structures can be described in the (3+1)-dimensional monoclinic X2/c(α,0,γ)0s superspace group (where X is ½, ½, 0, ½) with modulation wavevectors q = (0.2943, 0, 0.5640) and q = (0.3366, 0, 0.5544) for phases (II) and (III), respectively. The completely ordered low-temperature phase (IV) was refined with the twinning model in the triclinic P{\overline 1} space group, revealing the existence of two domains. The dynamics of the disordered anionic substructure in the 4apFeS crystal seems to play an essential role in the phase transition mechanisms. The discrete organic moieties were found to be fully ordered even at room temperature.

Reversiblechair↔skewconformational interconversion of 1,3,2-dioxaphosphorinane ring in the solid state

2016 ◽  
Vol 72 (1) ◽  
pp. 117-125 ◽  
Author(s):  
Katarzyna Anna Ślepokura
Keyword(s):  
Phase Transitions ◽  
Single Crystal ◽  
Dihydroxyacetone Phosphate ◽  
Temperature Phase ◽  
Coordination Geometry ◽  
Phosphate Anion ◽  
X Ray ◽  
X Ray Crystallography ◽  
Cyclic Phosphate ◽  
Low Temperature Phase

β-NH4[(MeO)2cDHAP] (where cDHAP is cyclic dihydroxyacetone phosphate) has been investigated by X-ray crystallography in the temperature range 350–100 K. Three reversible single-crystal-to-single-crystal phase transitions have been examined and four phases (high-, room-, medium- and low-temperature phase, HTP, RTP, MTP and LTP, respectively) have been structurally determined: HTP (at 350 K,P21/a,Z= 24), RTP (290 K, P \overline{1},Z= 12), MTP (205 K,P21/a,Z= 4) and LTP (100 K, P \overline{1},Z= 24). Various puckering modes of the 1,3,2-dioxaphosphorinane ring of the organic cyclic phosphate anion have been revealed in the crystal:chairandskew. Thechair↔skewring flipping, which has been shown to take place during the phase transitions, results in various populations ofskewandchairconformers in different phases. The flexibility in the coordination geometry of ammonium cations is considered to assist in the conformational flexibility of the dioxaphosphorinane ring.

From six- to five-coordinated SbIII in [(CH3)3PH]3[Sb2Cl9]: transition pathways from single-crystal X-ray diffraction

2008 ◽  
Vol 64 (5) ◽  
pp. 558-566 ◽  
Author(s):  
Anna Gagor ◽  
Maciej Wojtaś ◽  
Adam Pietraszko ◽  
Ryszard Jakubas
Keyword(s):  
Phase Transitions ◽  
Phase I ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Octahedral Environment ◽  
Transition Pathways ◽  
Cl Atoms ◽  
Unusual Increase

[(CH3)3PH]3[Sb2Cl9] experiences four phase transitions which were found by means of calorimetry, thermogravimetry and X-ray diffraction. The crystal structure was solved in the space group P63/mmc at 382 K (phase I), Pnam at 295 K (phase II) and Pna21 at 175 K (phase V). We observed an unusual increase in symmetry from the monoclinic to the orthorhombic form at the IV\rightarrowV transition. The parent hexagonal high-temperature phase I consists of highly disordered [(CH3)3PH]+ cations and [Sb2Cl9]3− anions with an octahedral environment of SbIII. The transition from phases I to II is associated with the ordering of [(CH3)3PH]+ cations. Moreover, the successive transformations from phases I to V are related to the change in the arrangement of Cl atoms in [Sb2Cl9]3− anions from the discrete `face-sharing bioctahedra' (phase I) to two corner-sharing square pyramids. A mechanism for the phase transitions is proposed. It is observed that weak C—H...Cl interactions are responsible for the structure arrangement in low-temperature phases.

An investigation into the temperature phase transitions of synthesized materials with Al- and Mg-doped lithium manganese oxide spinels by in situ powder X-ray diffraction

2016 ◽  
Vol 32 (1) ◽  
pp. 23-30
Author(s):  
C. D. Snyders ◽  
E. E. Ferg ◽  
D. Billing
Keyword(s):  
Phase Transitions ◽  
Intermediate Phase ◽  
Phase Changes ◽  
Synthesis Process ◽  
Temperature Phase ◽  
Gravimetric Analysis ◽  
Spinel Oxide ◽  
X Ray Diffraction ◽  
X Ray

Three spinel materials were prepared and characterized by in situ powder X-ray diffraction (PXRD) techniques to track their phase changes that occurred in the typical batch synthesis process from a sol–gel mixture to the final crystalline spinel oxide. The materials were also characterized by thermal gravimetric analysis, whereby the materials decomposition mechanisms that were observed as the precursor, was gradually heated to the final oxide. The results showed that all the materials achieved their total weight loss at about 400 °C. The in situ PXRD analysis showed the progression of the phase transitions where certain of the materials changed from a crystalline precursor to an amorphous intermediate phase and finally to the spinel cathode oxide (Li1.03Mg0.2Mn1.77O4). For other materials, the precursor would start as an amorphous phase and upon heating, convert into an impure intermediate phase (Mn2O3) before forming the final spinel oxide (Li1.03Mn1.97O4). On the other hand, the LiAl0.4Mn1.6O4 would start with an amorphous precursor, with no intermediate phases and immediately formed the final spinel oxide phase. The in situ PXRD study also showed the increases in the materials respective lattice parameters of the crystalline unit cells upon heating and the significant increases in their crystallite sizes when heated above 600 °C.

scholarly journals Inorganic Anion Regulates the Phase Transition in Two Organic Cation Salts Containing [(4-Nitroanilinium)(18-crown-6)]+ Supramolecules

2017 ◽  
Author(s):  
Yuan Chen ◽  
Yang Liu ◽  
Binzu Gao ◽  
Chuli Zhu ◽  
Zunqi Liu
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Variable Temperature ◽  
Structural Phase ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Space Group ◽  
X Ray

Two novel inorganic–organic hybrid supramolecular assemblies, namely, (4-HNA)(18-crown-6)(HSO4) (1) and (4-HNA)2(18-crown-6)2(PF6)2(CH3OH) (2) (4-HNA = 4-nitroanilinium), were synthesized and characterized by infrared spectroscopy, single X-ray diffraction, differential scanning calorimetry (DSC), and temperature-dependent dielectric measurements. The two compounds underwent reversible phase transitions at about 255 K and 265 K, respectively. These phase transitions were revealed and confirmed by the thermal anomalies in DSC measurements and abrupt dielectric anomalies during heating. The phase transition may have originated from the [(4-HNA)(18-crown-6)]+ supramolecular cation. The inorganic anions tuned the crystal packings and thus influenced the phase-transition points and types. The variable-temperature X-ray diffraction data for crystal 1 revealed the occurrence of a phase transition in the high-temperature phase with the space group of P21/c and in the low-temperature phase with the space group of P21/n. Crystal 2 exhibited the same space group P21/c at different temperatures. The results indicated that crystals 1 and 2 both underwent an iso-structural phase transition.

X-Ray Diffraction Study of the Low Temperature Phase Transitions of CuBrTe and CuITe

1992 ◽  
Vol 61 (12) ◽  
pp. 4659-4660 ◽  
Author(s):  
Takashi Sakuma ◽  
Tadahiro Kaneko ◽  
Haruyuki Takahashi ◽  
Kōji Honma ◽  
Robert B. Beeken
Keyword(s):  
Phase Transitions ◽  
Low Temperature ◽  
Diffraction Study ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Low Temperature Phase

Crystal structures and phase transitions of imidazolium hypodiphosphates

2020 ◽  
Vol 76 (5) ◽  
pp. 939-947
Author(s):  
Daria Budzikur ◽  
Przemysław Szklarz ◽  
Vasyl Kinzhybalo ◽  
Katarzyna A. Ślepokura
Keyword(s):  
Phase Transitions ◽  
Low Temperature ◽  
Crystal Structures ◽  
Dynamic Properties ◽  
Structural Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Compound I ◽  
X Ray ◽  
Imidazolium Cations

Two imidazolium hypodiphosphates, (C3H5N2)(H3P2O6) (I) and (C3H5N2)2(H2P2O6) (II), have been synthesized and structurally characterized. In both metal-free organic–inorganic hybrids (I) and (II), the hypodiphosphate mono- and dianions, (H3P2O6)− and (H2P2O6)2−, form hydrogen-bonded frameworks of different types, to which the organic cations are linked via N—H...O and C—H...O hydrogen bonds. The purity of the compounds was confirmed by powder X-ray diffraction. Differential scanning calorimetry of compound (I) revealed two structural phase transitions: continuous at 311.8 K [cooling/heating; from high-temperature phase (HTP) to room-temperature phase (RTP)] and a discontinuous one at 287.9/289.2 K [RTP → low-temperature phase (LTP)]. Compound (I) is characterized in a wide temperature range by single-crystal and powder X-ray diffraction methods. Crystal structures of high- and low-temperature phases are determined, which show orthorhombic (HTP, Pnna, No. 52) → monoclinic (LTP, P21/n11, No. 14, a-axis doubled) structural change on cooling with an intermediate incommensurately modulated phase (RTP). Dynamic properties of polycrystalline (I) were studied by means of dielectric spectroscopy. The dielectric behaviour is explained by the motion of imidazolium cations.

High-temperature phase transitions in CsH2PO4 under ambient and high-pressure conditions: A synchrotron x-ray diffraction study

2007 ◽  
Vol 127 (19) ◽  
pp. 194701 ◽  
Author(s):  
Cristian E. Botez ◽  
Juan D. Hermosillo ◽  
Jianzhong Zhang ◽  
Jiang Qian ◽  
Yusheng Zhao ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
High Temperature ◽  
Diffraction Study ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray
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