Solid-state behaviors of imines: Colossal biaxial positive thermal expansion, motion capability, and phase transitions

Thermal expansion is investigated for halogen-bonded co-crystals containing molecules that exhibit dynamic motion, lack motion ability, or experience static disorder.

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Phase Transition Studies across Isotropic-Smectic A and Smectic A-Smectic F Phases in 90.4

Zeitschrift für Naturforschung A ◽

10.1515/zna-1989-0106 ◽

1989 ◽

Vol 44 (1) ◽

pp. 23-25

Author(s):

D. M. Potukuchi ◽

P. Bhaskara Rao ◽

N. V. S. Rao ◽

V.G. K. M. Pisipati

Keyword(s):

Phase Transition ◽

Differential Scanning Calorimetry ◽

Thermal Expansion ◽

Phase Transitions ◽

Pressure Dependence ◽

Scanning Calorimetry ◽

First Order ◽

Smectic A ◽

Density Results ◽

Transition Studies

Abstract The temperature dependence of the density of N(p-n-nonyloxy benzylidene)p-n-butylaniline (90.4) is studied. The compound exhibits smectic A, smectic F and smetic G phases. The isotropicsmectic A (IA) and smetic A-smectic F phase transitions are found to be first order. The calculated thermal expansion coefficient and differential scanning calorimetry support the density results. The density jumps, associated enthalpies and the estimated pressure dependence of the transition temperatures for IA transitions in other compounds are also presented.

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Origin of the Giant Negative Thermal Expansion inMn3(Cu0.5Ge0.5)N

Advances in Condensed Matter Physics ◽

10.1155/2012/913168 ◽

2012 ◽

Vol 2012 ◽

pp. 1-7 ◽

Cited By ~ 5

Author(s):

B. Y. Qu ◽

H. Y. He ◽

B. C. Pan

Keyword(s):

Phase Transition ◽

Thermal Expansion ◽

Magnetic Phase Transition ◽

First Principles ◽

Magnetic Phase ◽

Lattice Vibration ◽

Negative Thermal Expansion ◽

First Principles Calculations ◽

Temperature Dependent ◽

Thermal Expansion Property

The giant negative thermal expansion in the Ge-doped antiperovskite Mn3CuN compound is theoretically studied by using the first principles calculations. We propose that such a negative thermal expansion property is essentially attributed to the magnetic phase transition, rather than to the lattice vibration of the Ge-doped compound. Furthermore, we found that the doped Ge atoms in the compound significantly enhance the antiferromagnetic couplings between the nearest neighboring Mn ions, which effectively stabilizes the magnetic ground states. In addition, the nature of the temperature-dependent changes in the volume of the Ge-doped compound was revealed.

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Studies on the interaction between two correlated electronic bands. I. Phase transition in NiS

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1980.0147 ◽

1980 ◽

Vol 373 (1753) ◽

pp. 253-268 ◽

Cited By ~ 2

Keyword(s):

Phase Transition ◽

Phase Transitions ◽

Density Of States ◽

Magnetic Phase ◽

Magnetic Phase Transitions ◽

Temperature Dependent ◽

Interacting Electrons

An expression for the density of states of two electronic bands with intraand inter-band correlations has been derived. The consequences of the inter-band interaction on Mott-Hubbard split bands are discussed. The model is applied to explain the metal, semi-metal and magnetic phase transitions in NiS by using a semi-elliptical form for the density of states of non-interacting electrons. It is shown that the temperature-dependent overlap and hybridization parameters between d- and p-bands can provoke both the phase transitions in NiS as pointed out earlier by White & Mott (1971)

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Disorder in crystals of dioxofluorotungstates, (NH4)2WO2F4 and Rb2WO2F4

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768108033053 ◽

2008 ◽

Vol 64 (6) ◽

pp. 645-651 ◽

Cited By ~ 23

Author(s):

Anatoly A. Udovenko ◽

Natalia M. Laptash

Keyword(s):

Phase Transition ◽

Phase Transitions ◽

Symmetry Axis ◽

Crystal Form ◽

X Ray Diffraction ◽

Twin Structure ◽

Static Disorder ◽

X Ray ◽

Independent States ◽

Lower Temperature

Dioxotetrafluorotungstates (NH4)2WO2F4 [(I) at 297 K and (II) at 133 K] and Rb2WO2F4 (III) were synthesized in a single-crystal form and their structures were determined by X-ray diffraction. Two independent states of the cis-WO2F4 octahedron are characteristic of static and dynamic disorder in structure (I). Dynamically disordered W2 is displaced from the symmetry axis producing four possible orientations of anion that permits O and F atoms to be identified in separate orientations owing to the inherent differences between W—O and W—F bonding. After the phase transition at lower temperature (201 K), (I) transforms into the twin structure (II) with complete O/F ordering. Structure (III) is characterized by full O/F static disorder without any phase transitions at lower temperature.

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CHIRAL AND UA(1) PHASE TRANSITIONS IN π0, η AND η′ MESONS

Modern Physics Letters A ◽

10.1142/s0217732306019529 ◽

2006 ◽

Vol 21 (19) ◽

pp. 1529-1539

Author(s):

SURAJIT SEN ◽

B. BAGCHI

Keyword(s):

Phase Transition ◽

Phase Transitions ◽

Quark Gluon Plasma ◽

Mass Spectra ◽

Gluon Plasma ◽

Temperature Dependent ◽

Chiral Phase ◽

Chiral Phase Transition ◽

Mixing Angles ◽

Pseudoscalar Mesons

We have generalized the Pisarsky–Wilczek model of studying the UA(1) phase transition in π0, η and η′ system by incorporating the chiral phase transition. The mass-squared matrix of the neutral pseudoscalar mesons is revisited explicitly from the chiral effective action which necessitates the mixing among the unmixed states to get the physical states. The derivation of the mass spectra of the neutral pseudoscalar mesons shows that apart from their masses, the mixing angles also become temperature dependent. Based on the dilute instanton gas approximation we show that, the UA(1) phase transition along with the chiral phase transition plays an important role in the process of hadronization of the quark–gluon plasma with the quarks of three flavors.

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TEM of Phase Transitions in Tridymite and Cristobalite Based Materials.

Microscopy and Microanalysis ◽

10.1017/s1431927600034280 ◽

2000 ◽

Vol 6 (S2) ◽

pp. 358-359

Author(s):

Gustaaf Van Tendeloo

Keyword(s):

Phase Transition ◽

Phase Transitions ◽

High Temperature ◽

Solid State ◽

Wide Temperature Range ◽

Room Temperature ◽

Paraelectric Phase ◽

High Temperature Phase ◽

Temperature Phase ◽

Extended Defects

We have determined the structure of the paraelectric phase of BaAl2O4, which is a stuffed tridymite, by different TEM techniques and we will describe the phase transition between the ferroelectric room temperature phase and the paraelectric high temperature phase. We have also obtained HREM images of the higly radiation sensitive acristobalite phase of (Si0,9 Ge0,1)O2 and analysed the extended defects in this material.The stuffed tridymite BaAl2O4 is ferroelectric at room temperature and undergoes a paraelectric-ferroelectric (PEFE) phase transition. The transition is reversible, takes place over a wide temperature range (400K-670K) and has a dynamical character. BaAl2O4 is easily obtained by solid state reaction of BaCO3, and A12O4,. The stoichiometric amounts of the initial reagents were mixed, grinded in an agate mortar under acetone and pressed into a pellet. The pellet was annealed in alumina crucibles at 1000 °C and 1300 °C for 40 h in air and furnace cooled.

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Thermophysical Properties of Gd2O3 Doped SrHfO3 Ceramic

Materials Science Forum ◽

10.4028/www.scientific.net/msf.816.237 ◽

2015 ◽

Vol 816 ◽

pp. 237-241 ◽

Cited By ~ 3

Author(s):

Wen Ma ◽

Yi Ren ◽

Xi Long Jin ◽

Ya Hong Liang ◽

Bao Dong Chen ◽

...

Keyword(s):

Thermal Conductivity ◽

Thermal Expansion ◽

Phase Transitions ◽

High Temperature ◽

Solid State ◽

Solid State Reaction Method ◽

Reaction Method ◽

Long Period ◽

Thermal Expansion Coefficients ◽

Expansion Coefficients

Gd2O3 (10mol%) doped SrHfO3 (Sr (Hf0.9Gd0.1)O2.95) was synthesized by solid state reaction method. The phase stability of the synthesized Sr (Hf0.9Gd0.1)O2.95 powder at high temperature of 1450 oC for a long period and in a temperature range of RT-1400 oC was characterized by XRD and DSC, respectively. The thermal expansion coefficients (TECs) of bulk Sr (Hf0.9Gd0.1)O2.95 were recorded by a high-temperature dilatometer, indicating that the phase transitions of SrHfO3 are suppressed remarkably by doping Gd2O3. The thermal conductivity of bulk Sr (Hf0.9Gd0.1)O2.95 at 1000 oC is ~1.95 W/m·K, which is ~11% lower than that of bulk 8YSZ.

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The Influence of d10-d10 Interactions in Ag5Te1.8Se0.2Cl and Ag5Te1.6Se0.4Cl on Structural and Thermoelectric Properties

Zeitschrift für Naturforschung B ◽

10.1515/znb-2011-1005 ◽

2011 ◽

Vol 66 (10) ◽

pp. 1005-1014

Author(s):

Nadine Eckstein ◽

Jean-Louis Bobet ◽

Bernard Chevalier ◽

Tom Nilges

Keyword(s):

Crystal Structure ◽

Phase Transition ◽

Thermal Expansion ◽

Thermal Diffusivity ◽

Negative Thermal Expansion ◽

Silver Ions ◽

Structural Features ◽

Temperature Dependent ◽

Disorder Phase Transition ◽

Structure Determinations

Measurements of the thermopower and of the thermal diffusivity and a detailed analysis of the structural features by temperature-dependent single-crystal structure determinations of silver ionconducting Ag5Te1.8Se0.2Cl and Ag5Te1.6Se0.4Cl were performed to investigate the interaction of silver ions in their disordered state. The substituted phases show an order/disorder phase transition at 273.3(2) and 302.5(2) K, respectively, accompanied by a drop of the thermal diffusivity and a minimum plateau of the thermopower right after the transition. Silver ions are arranged in welldefined strands along the crystallographic c axis characterized by a set of not fully occupied sites. Ag5Te1.6Se0.4Cl shows a negative thermal expansion during temperature rise right after the silver order/disorder phase transition; this is explicable by attractive d10-d10 interactions within the disordered silver substructure. After the minimum values of the thermopower have been reached, these values rise in parallel to the decrease of the d10-d10 interactions. Ag5Te1.6Se0.4Cl shows a very low value of the thermal diffusivity of 0.070 mm2 s−1 at 300.7 K.

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