scholarly journals The unified history of the viscous accelerating universe and phase transitions

2021 ◽  
pp. 115646
Author(s):  
A.V. Astashenok ◽  
S.D. Odintsov ◽  
A.S. Tepliakov
Keyword(s):  
Phase Transitions ◽  
Accelerating Universe ◽  
History Of

Multiple phase transitions investigated by high-speed TEM

1990 ◽  
Vol 48 (4) ◽  
pp. 550-551
Author(s):  
Oleg Bostanjoglo ◽  
Peter Thomsen-Schmidt
Keyword(s):  
Phase Transitions ◽  
High Speed ◽  
Short Exposure ◽  
Semiconductor Film ◽  
Time Resolved ◽  
Short Exposure Time ◽  
Multiple Phase ◽  
Model Substance ◽  
History Of ◽  
Electron Image

Thin GexTe1-x (x = 0.15-0.8) were studied as a model substance of a composite semiconductor film, in addition being of interest for optical storage material. Two complementary modes of time-resolved TEM were used to trace the phase transitions, induced by an attached Q-switched (50 ns FWHM) and frequency doubled (532 nm) Nd:YAG laser. The laser radiation was focused onto the specimen within the TEM to a 20 μm spot (FWHM). Discrete intermediate states were visualized by short-exposure time doubleframe imaging /1,2/. The full history of a transformation was gained by tracking the electron image intensity with photomultiplier and storage oscilloscopes (space/time resolution 100 nm/3 ns) /3/. In order to avoid radiation damage by the probing electron beam to detector and specimen, the beam is pulsed in this continuous mode of time-resolved TEM,too.Short events ( <2 μs) are followed by illuminating with an extended single electron pulse (fig. 1c)

One Hundred Years of Ferroelectrics

2021 ◽  
Vol 30 (9) ◽  
pp. 4-7
Author(s):  
Da Jeong KIM ◽  
Tae Kwon SONG
Keyword(s):  
Phase Transitions ◽  
Basic Science ◽  
Optical Devices ◽  
Rochelle Salt ◽  
Switching Dynamics ◽  
History Of

The brief history of ferroelectrics and related piezoelectrics and pyroelectrics is reviewed in terms of basic science and application. In 1920, J. Valasek discovered the ferroelectricity of Rochelle salt. Since then ferroelectrics have been widely used for sensors, actuators, and electronic and optical devices. Also, phase transitions in solids and hysteretic switching dynamics have been studied in ferroelectrics.

Early Work on Defect Driven Phase Transitions

2016 ◽  
Vol 30 (30) ◽  
pp. 1630018 ◽  
Author(s):  
J. Michael Kosterlitz ◽  
David J. Thouless
Keyword(s):  
Phase Transitions ◽  
Superfluid Helium ◽  
Topological Defects ◽  
Early History ◽  
Two Dimensional ◽  
Helium Films ◽  
Experimental Systems ◽  
History Of

This article summarizes the early history of the theory of phase transitions driven by topological defects, such as vortices in superfluid helium films or dislocations and disclinations in two-dimensional solids. We start with a review of our two earliest papers, pointing out their errors and omissions as well as their insights. We then describe the work, partly done by Kosterlitz but mostly done by other people, which corrected these oversights, and applied these ideas to experimental systems, and to numerical and experimental simulations.

ZrCuSiAs-type Phosphide Oxides: TbRuPO, DyRuPO, the Series LnOsPO (Ln = La, Ce, Pr, Nd, Sm), and ThAgPO

2008 ◽  
Vol 63 (8) ◽  
pp. 934-940 ◽  
Author(s):  
Wolfgang Jeitschko ◽  
Barbara I. Zimmer ◽  
Robert Glaum ◽  
Ludger Boonk ◽  
Ute Ch. Rodewald
Keyword(s):  
Phase Transitions ◽  
Solid State ◽  
Single Crystal ◽  
Chemical Bonding ◽  
Large Family ◽  
Type Structure ◽  
Solid State Reactions ◽  
X Ray ◽  
History Of ◽  
High Transition

The title compounds were prepared by solid-state reactions and via tin and NaCl/KCl fluxes. They crystallize with the tetragonal ZrCuSiAs-type structure (P4/nmm, Z = 2), which was refined from single-crystal X-ray data of PrOsPO (a = 402.1(1), c = 824.0(1) pm, wR2 = 0.0490, 365 F2) and ThAgPO (a = 396.1(1), c = 877.8(1) pm, wR2 = 0.0307, 314 F2). They belong to a large family of isotypic compounds, of which several, mainly fluorine doped, iron containing compounds LnFeAsO1-xFx were discovered to be superconducting with relatively high transition temperatures only recently in other laboratories. Chemical bonding in these compounds is briefly discussed, and the importance of the weakly bonding Fe-Fe interactions for the phase transitions and the superconductivity is emphasized from the viewpoint of structural chemistry. A brief account of the history of the preparation of these compounds in our laboratory is given. Originally many of these compounds were obtained only in small amounts as byproducts in the course of the preparation of ternaries.

scholarly journals The size factor in phase transitions: its role in polymer crystal formation and wider implications

1994 ◽  
Vol 348 (1686) ◽  
pp. 3-17 ◽  
Keyword(s):  
Phase Transitions ◽  
Past History ◽  
Hexagonal Phase ◽  
Size Factor ◽  
Crystal Formation ◽  
Lamellar Thickness ◽  
Phase Development ◽  
Kinetic Rates ◽  
History Of ◽  
Special Instance

It is shown that under specifiable circumstances stabilities of competing phases can invert with size: specifically, that a phase which is metastable when of infinite size can become the stable one when of sufficiently small dimensions. It follows that phase development, crystal growth in particular, may start in a phase variant which becomes metastable when the new phase is fully developed. If it stays in this form Ostwald’s rule of stages will seem to be obeyed, if it transforms into the phase of ultimate stability the past history of phase development becomes obliterated. In the special instance of flexible polymers, polyethylene in particular, there can be thickening growth while in the metastable ‘mobile’ phase (hexagonal phase in polyethylene), hence residence within this phase will determine the lamellar thickness, consequently also the final texture of the crystallizing material. Based on these considerations the two so far essentially disconnected areas of chain folded and extended chain type crystallization can be visualised within a unified frame work with new, broadened perspectives for the whole subject of polymer crystallization. In addition, the scheme creates a junction between thermodynamic (stability) and kinetic (rates) aspects of phase transitions in wider generality.

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