Special Issue "Pressure-Induced Phase Transformations"

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Crystalline Materials".

Deadline for manuscript submissions: 31 October 2019.

Special Issue Editor

Guest Editor
Prof. Dr. Daniel Errandonea Website E-Mail
Departamento de Fisica Aplicada, Universidad de Valencia, C/Dr. Moliner 50, Burjassot, E-46100, Valencia, Spain
Phone: +34 963544475
Interests: high-pressure; phase trasitions; oxides; x-ray diffraction; novel technological materials

Special Issue Information

Dear Colleagues,

The study of phase transitions in solids under high pressure and high temperature is a very active research field. In the last few decades, thanks to the development of experimental techniques and computer simulations, there has been a plethora of important discoveries. Many of the achievements done in recent years affect various research fields going from solid-state physics, chemistry, and materials science to geophysics. They do not only involve the deepening of the knowledge on solid-sold phase transitions but also a better understanding of melting under compression. The impact of pressure on structural, chemical, and physical properties and several modern discoveries are the principal reasons for producing the current Special Issue.

This Special Issue on “Pressure-Induced Phase Transformations” has the aim to give a forum for describing and discussing contemporary achievements. The goal is to give special emphasis to phase transitions and their effects on different physical properties, but other topics, in special melting studies, are not excluded. Authors are invited to contribute to the Special Issue with articles presenting new experimental and theoretical advances. Contributions discussing the relationships of phase transformations in solids under high pressure, the mechanism of these transformations, and their influence in physical and chemical properties are welcome.

Researchers working in a wide range of disciplines are invited to contribute to this Special Issue. The topics summarized under the keywords given below are only broadly examples of the greater number of topics in mind. The volume is especially open not only to original manuscripts but also to feature and short review articles of current hot topics.

Prof. Dr. Daniel Errandonea
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • High pressure research
  • Phase transitions
  • Structural properties
  • Transition mechanisms
  • Equation of state
  • Symmetry-breaking
  • Melting curves

Published Papers (3 papers)

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Research

Open AccessArticle
Fe Melting Transition: Electrical Resistivity, Thermal Conductivity, and Heat Flow at the Inner Core Boundaries of Mercury and Ganymede
Crystals 2019, 9(7), 359; https://doi.org/10.3390/cryst9070359 - 15 Jul 2019
Abstract
The electrical resistivity and thermal conductivity behavior of Fe at core conditions are important for understanding planetary interior thermal evolution as well as characterizing the generation and sustainability of planetary dynamos. We discuss the electrical resistivity and thermal conductivity of Fe, Co, and [...] Read more.
The electrical resistivity and thermal conductivity behavior of Fe at core conditions are important for understanding planetary interior thermal evolution as well as characterizing the generation and sustainability of planetary dynamos. We discuss the electrical resistivity and thermal conductivity of Fe, Co, and Ni at the solid–liquid melting transition using experimental data from previous studies at 1 atm and at high pressures. With increasing pressure, the increasing difference in the change in resistivity of these metals on melting is interpreted as due to decreasing paramagnon-induced electronic scattering contribution to the total electronic scattering. At the melting transition of Fe, we show that the difference in the value of the thermal conductivity on the solid and liquid sides increases with increasing pressure. At a pure Fe inner core boundary of Mercury and Ganymede at ~5 GPa and ~9 GPa, respectively, our analyses suggest that the thermal conductivity of the solid inner core of small terrestrial planetary bodies should be higher than that of the liquid outer core. We found that the thermal conductivity difference on the solid and liquid sides of Mercury’s inner core boundary is ~2 W(mK)−1. This translates into an excess of total adiabatic heat flow of ~0.01–0.02 TW on the inner core side, depending on the relative size of inner and outer core. For a pure Fe Ganymede inner core, the difference in thermal conductivity is ~7 W(mK)−1, corresponding to an excess of total adiabatic heat flow of ~0.02 TW on the inner core side of the boundary. The mismatch in conducted heat across the solid and liquid sides of the inner core boundary in both planetary bodies appears to be insignificant in terms of generating thermal convection in their outer cores to power an internal dynamo suggesting that chemical composition is important. Full article
(This article belongs to the Special Issue Pressure-Induced Phase Transformations)
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Open AccessArticle
Stepwise Homogeneous Melting of Benzene Phase I at High Pressure
Crystals 2019, 9(6), 279; https://doi.org/10.3390/cryst9060279 - 28 May 2019
Abstract
We investigate, using molecular dynamics simulations, the spontaneous homogeneous melting of benzene phase I under a high pressure of 1.0 GPa. We find an apparent stepwise transition via a metastable crystal phase, unlike the direct melting observed at ambient pressure. The transition to [...] Read more.
We investigate, using molecular dynamics simulations, the spontaneous homogeneous melting of benzene phase I under a high pressure of 1.0 GPa. We find an apparent stepwise transition via a metastable crystal phase, unlike the direct melting observed at ambient pressure. The transition to the metastable phase is achieved by rotational motions, without the diffusion of the center of mass of benzene. The metastable crystal completely occupies the whole space and maintains its structure for at least several picoseconds, so that the phase seems to have a local free energy minimum. The unit cell is found to be unique—no such crystalline structure has been reported so far. Furthermore, we discuss the influence of pressure control on the melting behavior. Full article
(This article belongs to the Special Issue Pressure-Induced Phase Transformations)
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Open AccessArticle
Pressure Effects on the Optical Properties of NdVO4
Crystals 2019, 9(5), 237; https://doi.org/10.3390/cryst9050237 - 06 May 2019
Cited by 2
Abstract
We report on optical spectroscopic measurements in pure NdVO4 crystals at pressures up to 12 GPa. The influence of pressure on the fundamental absorption band gap and Nd3+ absorption bands has been correlated with structural changes in the crystal. The experiments [...] Read more.
We report on optical spectroscopic measurements in pure NdVO4 crystals at pressures up to 12 GPa. The influence of pressure on the fundamental absorption band gap and Nd3+ absorption bands has been correlated with structural changes in the crystal. The experiments indicate that a phase transition takes place between 4.7 and 5.4 GPa. We have also determined the pressure dependence of the band-gap and discussed the behavior of the Nd3+ absorption lines under compression. Important changes in the optical properties of NdVO4 occur at the phase transition, which, according to Raman measurements, corresponds to a zircon to monazite phase change. In particular, in these conditions a collapse of the band gap occurs, changing the color of the crystal. The changes are not reversible. The results are analyzed in comparison with those deriving from previous studies on NdVO4 and related vanadates. Full article
(This article belongs to the Special Issue Pressure-Induced Phase Transformations)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Electrical transport property of [email protected] under high pressure

Authors: Zhongyan Wu, Jaeyong Kim, Alexander Soldatov, Lin Wang

Abstrsct: The goal of this study was to investigate the phase transition of the solvated C60 under high pressure from the view point of electrical transport property. It was found that the resistance of the sample shows a rapid drop as pressure increases but still stay as a semiconductor even up to the highest pressure studied. At around 25GPa the conductivity value reached the minimum and started to rise which corresponding to the pressure-induced collapse of the fullerene cage. The conductivity showed a larger hysteresis during decompression from pressure higher than 25GPa, suggesting the different transport behavior of retained and collapsed fullerenes.

 

Title: Mechanisms of pressure induced phase transitions by real time Laue diffraction

Authors: D. Popov, N. Velisavljevic

Abstrsct: Synchrotron radiation Laue diffraction is widely implemented to characterize microstructure of materials. Exciting feature of this technique is that comparable number of reflections can be measured multiple orders of magnitude faster than if use monochromatic beam. This makes polychromatic beam diffraction a powerful tool for microstructural studies, critical for understanding of pressure induced phase transitions mechanisms by conducting in-situ and in-operando measurements. Current status of this technique is presented along with some case studies. The major aspects of mechanisms of pressure induced phase transitions, available by real-time Laue diffraction, are discussed, including crystal morphology, orientation relations, twinning, strain. New experimental setup, specifically dedicated to in-situ and in-operando microstructural studies by Laue diffraction under high pressure is presented.

 

Title: Pressure tuned interactions in Quantum Spin Liquids and Frustrated magnets

Authors: T. Biesner and E. Uykur

Abstrsct: Quantum Spin Liquids are prime examples for strongly entangled phases of matter with unconventional exotic excitations. Here, strong quantum fluctuations prohibit the freezing of the spin system, while its counterpart, the Frustrated magnet still shows a magnetic ground state. Pressure approved to be an effective tuning parameter of structural properties and electronic correlations. Nevertheless, the ability to influence the magnetic phases should not be forgotten. We are going to review experimental progress in the field of pressure tuned magnetic interactions in candidate systems. Elaborating on the possibility of tuned quantum phase transitions, we are further going to show that chemical or external pressure can be a suitable parameter in these exotic states of matter.

 

Title: New insights into high pressure phase transitions from Landau theory based on symmetry-adapted finite strains

Authors: Andreas Tröster

Abstrsct: Landau theory (LT) coupled to infinitesimal strain is a cornerstone of the theory of structural phase transitions. However, at high pressures this approach breaks down due to the appearance of large strains and the accompanying nonlinear elastic energy contributions. In contrast, in density functional theory (DFT) strain is easy to control, but entropic effects are difficult to incorporate since DFT is a genuine zero temperature method. Recently we have shown how to combine the strengths of these two antipodal approaches by constructing a high pressure extension of conventional LT with the help of DFT. This finite strain Landau theory (FSLT) theory has proved to yield a concise numerical framework for the description of high-pressure phase transition in some prominent perovskites.

In the present paper we show that reformulating FSLT in terms of symmetry-adaped strains does not only help to make its relation to the traditional approach more transparent. It moreover reveals a somewhat surprising but very convenient internal mathematical symmetry that allows to largely eliminate the remaining drawbacks that result from the use of truncated power series in the elastic background strain. The resulting formalism is employed in a discussion of the high-pressure phase transition of KMnF3, for which the available ambient and high pressure experimental data reveal a considerable ambiguity but nevertheless indicate a breakdown of the conventional infinitesimal strain description.

 

Title: Sesquioxides at high pressure

Authors: F. J. Manjón and J. A. Sans

Abstrsct: In this work, we review the behavior of the different families of sesquioxides under compression. They include those with transition metal atoms, those with group 13 and 15 atoms and those with rare-earth atoms. We have tried to rationalize crystalline structures at room pressure, unit cell volumes, bulk moduli, phase transition pressures, and high-pressure phases on a common basis.

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