Absence of the Structural Phase Transition in Ammonia Borane Dispersed in Mesoporous Silica: Evidence of Novel Thermodynamic Properties

2009 ◽  
Vol 113 (24) ◽  
pp. 10319-10321 ◽  
Author(s):  
Annalisa Paolone ◽  
Oriele Palumbo ◽  
Pasquale Rispoli ◽  
Rosario Cantelli ◽  
Tom Autrey ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermodynamic Properties ◽  
Mesoporous Silica ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Ammonia Borane

The structural phase transition of ammonia borane under high pressure

2020 ◽  
Vol 45 (58) ◽  
pp. 33047-33058
Author(s):  
Lan-Ting Shi ◽  
Cui-E Hu ◽  
Alfonso Muñoz ◽  
Lin-Xiang Ji ◽  
Yao-Yao Huang ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Ammonia Borane

Mesoscopic modeling of structural and thermodynamic properties of fluids confined by rough surfaces

2015 ◽  
Vol 17 (39) ◽  
pp. 26403-26416 ◽  
Author(s):  
Ketzasmin A. Terrón-Mejía ◽  
Roberto López-Rendón ◽  
Armando Gama Goicochea
Keyword(s):  
Phase Transition ◽  
Thermodynamic Properties ◽  
Interfacial Tension ◽  
Structural Phase Transition ◽  
Rough Surfaces ◽  
Structural Phase ◽  
Mesoscopic Modeling

Simulations show that the ordering of particles confined by rough surfaces induces a structural phase transition while the interfacial tension is insensitive to it.

An investigation of the structural phase transition of ammonia borane

2009 ◽  
Vol 521-522 ◽  
pp. 169-171 ◽  
Author(s):  
Annalisa Paolone ◽  
Oriele Palumbo ◽  
Pasquale Rispoli ◽  
Rosario Cantelli ◽  
Tom Autrey
Keyword(s):  
Phase Transition ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Ammonia Borane

First-Principles Study of Lattice Dynamics, Structural Phase Transition, and Thermodynamic Properties of Barium Titanate

2016 ◽  
Vol 71 (8) ◽  
pp. 759-768 ◽  
Author(s):  
Huai-Yong Zhang ◽  
Zhao-Yi Zeng ◽  
Ying-Qin Zhao ◽  
Qing Lu ◽  
Yan Cheng
Keyword(s):  
Phase Transition ◽  
Barium Titanate ◽  
Thermodynamic Properties ◽  
Structural Phase Transition ◽  
First Principles ◽  
Lattice Dynamics ◽  
Density Functional ◽  
Structural Phase ◽  
Rhombohedral Phase ◽  
Site Symmetry

AbstractLattice dynamics, structural phase transition, and the thermodynamic properties of barium titanate (BaTiO3) are investigated by using first-principles calculations within the density functional theory (DFT). It is found that the GGA-WC exchange-correlation functional can produce better results. The imaginary frequencies that indicate structural instability are observed for the cubic, tetragonal, and orthorhombic phases of BaTiO3 and no imaginary frequencies emerge in the rhombohedral phase. By examining the partial phonon density of states (PDOSs), we find that the main contribution to the imaginary frequencies is the distortions of the perovskite cage (Ti-O). On the basis of the site-symmetry consideration and group theory, we give the comparative phonon symmetry analysis in four phases, which is useful to analyze the role of different atomic displacements in the vibrational modes of different symmetry. The calculated optical phonon frequencies at Γ point for the four phases are in good agreement with other theoretical and experimental data. The pressure-induced phase transition of BaTiO3 among four phases and the thermodynamic properties of BaTiO3 in rhombohedral phase have been investigated within the quasi-harmonic approximation (QHA). The sequence of the pressure-induced phase transition is rhombohedral→orthorhombic→tetragonal→cubic, and the corresponding transition pressure is 5.17, 5.92, 6.65 GPa, respectively. At zero pressure, the thermal expansion coefficient αV, heat capacity CV, Grüneisen parameter γ, and bulk modulus B of the rhombohedral phase BaTiO3 are estimated from 0 K to 200 K.

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