Judging the phase transition pressure of the unknown parent phase if the resulting state is known

2020 ◽  
Vol 22 (2) ◽  
pp. 624-627
Author(s):  
Sheng-Hai Zhu ◽  
Han Qin ◽  
Wei Zeng ◽  
Dai-He Fan ◽  
Bin Tang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Parent Phase ◽  
Transition Pressure ◽  
Phase Transition Pressure ◽  
Transition Points ◽  
New Phase

Under the condition that the parent phase is unknown, we have directly judged the phase transition points from the new phase.

scholarly journals New Phase in Fluid Hydrogen at Room Temperature

2021 ◽  
Author(s):  
Atsuko Nakayama ◽  
Yuya Isurugi ◽  
Yuya Serizawa ◽  
Satoshi Nakano ◽  
Ayako Ohmura ◽  
...  
Keyword(s):  
Phase Transition ◽  
Room Temperature ◽  
Fluid Phase ◽  
Honeycomb Lattice ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transition Pressure ◽  
Peak Separation ◽  
Phase Transition Pressure ◽  
New Phase

Abstract The presence of phase-transition in hydrogen (H2) at around 560 megapascal (MPa) and room temperature was clarified by Raman and x-ray diffraction studies on both pure H2 and graphite-H2 mixture. H2 is intercalated into the nano-space of graphite, which lowers the transition pressure and temporally expands the size of the honeycomb lattice of graphite under pressure up to 600 MPa. It is supposed that is caused by a gas-liquid phase-transition. According to the peak analysis for Q1(J) mode, the ortho-para conversion of H2 gradually begins to appear after the phase-transition pressure even at room temperature, while peak separation is difficult to achieve under pressure above 1.6 gigapascal (GPa) because of significant overlapping of the peak intensities. Because we have missed the ortho-para conversion which could be observed in only such a small pressure range, the fluid phase at room temperature was full of mystery.

PRESSURE INDUCED PHASE TRANSITION (B3–B1) AND ELASTIC PROPERTIES OF II–VI ZnSe SEMICONDUCTORS

2012 ◽  
Vol 26 (14) ◽  
pp. 1250077
Author(s):  
DINESH VARSHNEY
Keyword(s):  
Phase Transition ◽  
Nearest Neighbor ◽  
Electron Shell ◽  
Phenomenological Approach ◽  
Interionic Interaction ◽  
Transition Pressure ◽  
Phase Transition Pressure ◽  
Reported Data ◽  
Three Body ◽  
Vdw Interaction

We evolve an effective interionic interaction potential (EIoIP) to investigate the pressure induced phase transitions from Zinc blende (B3) to Rocksalt (B1) structure in ZnSe semiconductor. The developed potential consists of the long-range Coulomb and three-body interactions (TBI) and the Hafemeister and Flygare type short-range (SR) overlap repulsion extended upto the second neighbor ions and the van der Waals (vdW) interaction. The three-body interactions arise from the electron-shell deformation when the nearest-neighbor ions overlap and has been employed for detailed studies of pressure-induced phase-transition behavior of ZnSe semiconductors. Our calculated value of the phase transition pressure (Pt) is higher and the magnitude of the discontinuity in volume at the transition pressure is consistent with reported data. The variation of second-order elastic constants with pressure resembles that observed in some binary semiconductors. It is inferred that the vdW interaction is effective in obtaining the Debye temperature, Gruneisen parameter, thermal expansion coefficient and compressibility. It is argued that the model with TBI (model II) has yielded somewhat more realistic predictions of the phase-transition and high-pressure behavior as compared to usual two-body potentials (model I) based on phenomenological approach.

Sign in / Sign up

Export Citation Format

Share Document