uu.seUppsala University Publications
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Synthesis and Tuning of Multifunctional Materials at High Pressure
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Mineralogy Petrology and Tectonics.ORCID iD: 0000-0002-7749-0402
2020 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

At the present stage, human society is developing at an unprecedented speed, facing an emergence of highly pressing challenges, e.g., information explosion, energy production problems, environmental pollution, climate problems. Functional materials with tailored properties are considered as holding a key to solving these problems. In this thesis, high-pressure techniques were employed to synthesize and tune the properties of multiferroic materials relevant to spintronic and light-harvesting applications, and multifunctional high-entropy alloys.

Melanostibite (Mn2FeSbO6, MFSO) is a very rare mineral discovered in Sweden. Previous studies indicate it is a potential multiferroic material with foreseen applications in information storage and spintronic devices. However, its multiferroic phase has not been synthesized yet. Herein, the structural evolution of MFSO was studied up to ~50 GPa, and the LiNbO3-type MFSO was synthesized at high pressure and moderate temperature. As a polar structure material, the LiNbO3-type MFSO represents a promising candidate for multiferroic materials. The double perovskite, Pb2CoTeO6, was also compressed to ~60 GPa, while no polar phase was discovered. The obtained results provide guidance to the synthesis of new multiferroic double perovskite.

Solar energy is a promising alternative to fossil fuels and thus a viable solution to the global energy problem. Light-harvesting materials, which absorb sunlight and transform it into electricity by the photovoltaic effect, represent the core part of solar cells. Currently, the dominant commercial light-harvesting material is silicon. However, silicon and recently emerged organic-inorganic perovskites have several drawbacks. Multiferroic oxides are considered as stable and nontoxic light-harvesting materials. But, their bandgap energies are generally too large for photovoltaic applications. Herein, high-pressure technique was applied to treat Mn3TeO6, and a quenchable phase of Mn3TeO6 displaying a greatly narrowed bandgap was synthesized. The measured absorption spectrum of the quenched phase reveals that it may be suitable for photovoltaic applications. The present research opens a green way to tune the bandgap energy of multiferroic.

High-entropy alloys (HEAs) were first synthesized in 2004. However, knowledge of this new class of promising alloys is still very limited, even in very fundamental aspects. The present results reveal that lattice distortion plays important roles in the phase transition of HEAs, and demonstrate the future possibility of designing the Invar high-entropy alloy, a promising structural material. The results show that it is possible to combine several practical properties in a single alloy, which will widen the range of applications of HEAs. 

The presented research demonstrates that high-pressure represents an effective way to tune various properties of materials, as well as can be applied for the synthesis of materials with exotic properties which are usually not stable or attainable at ambient conditions.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2020. , p. 71
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1883
Keywords [en]
double perovskite, multiferroic, bandgap engineering, high-entropy alloy, high pressure
National Category
Geosciences, Multidisciplinary
Research subject
Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
Identifiers
URN: urn:nbn:se:uu:diva-397718ISBN: 978-91-513-0825-8 (print)OAI: oai:DiVA.org:uu-397718DiVA, id: diva2:1372731
Public defence
2020-01-28, Axel Hambergsalen, Geocentrum, Villavägen 16, Uppsala, 10:00 (English)
Opponent
Supervisors
Available from: 2019-12-19 Created: 2019-11-25 Last updated: 2020-01-14
List of papers
1. Pressure-induced polymorphism and piezochromism in Mn2FeSbO6
Open this publication in new window or tab >>Pressure-induced polymorphism and piezochromism in Mn2FeSbO6
Show others...
2019 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 114, no 16, article id 162903Article in journal (Refereed) Published
Abstract [en]

In the last decade, major efforts have been devoted to searching for polar magnets due to their vast potential applications in spintronic devices. However, the polar magnets are rare because of conflicting electronic configuration requirements of ferromagnetism and electric polarization. Double-perovskite oxides with a polar structure containing transition metal elements represent excellent candidates for the polar magnet design. Herein, the crystal structure evolution of Mn2FeSbO6 (MFSO) was investigated at pressures reaching similar to 50 GPa by in situ synchrotron X-ray diffraction (XRD), Raman scattering, and ab initio calculation techniques. The XRD results reveal ilmenite-to perovskite-type phase transition at around 35 GPa. An additional intermediate phase, observed in the range of 31-36 GPa by Raman spectroscopy, but not the XRD technique, is proposed to represent the polar LiNbO3 phase. It is argued that this phase emerged due to the heating effect of the Raman-excitation laser. The LiNbO3-type MFSO compounds, displaying an intrinsic dipole ordering, represent a promising candidate for multiferroic materials. The detected phase transitions were found to be reversible although a significant hysteresis was noticeable between compression and decompression runs. Moreover, a pressure-induced piezochromism, signifying a bandgap change, was discovered by the direct visual observations and corroborated by ab initio calculations. The present study benefits an efficient high-pressure synthesis of polar magnetic double-perovskite oxides in the future.

Place, publisher, year, edition, pages
AMER INST PHYSICS, 2019
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-383857 (URN)10.1063/1.5090649 (DOI)000466264600024 ()
Available from: 2019-05-24 Created: 2019-05-24 Last updated: 2019-11-25Bibliographically approved
2. Pressure tuning of octahedral tilt in the ordered double perovskite Pb2CoTeO6
Open this publication in new window or tab >>Pressure tuning of octahedral tilt in the ordered double perovskite Pb2CoTeO6
Show others...
2019 (English)In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 801, p. 310-317Article in journal (Refereed) Published
Abstract [en]

Double perovskites represent a family of materials with promising fundamental properties (e.g. multiferroicity) and vast potential applications. However, the knowledge of pressure effects on the crystal structure of double perovskite is limited, which hinders their efficient synthesis using high-pressure techniques. Pb2CoTeO6 (PCTO) is considered as a good candidate for multiferroic materials, although a polymorph with a polar structure has not been synthesized yet. In the present study, the pressure effect on the crystal structure of PCTO was systematically studied by employing in situ synchrotron X-ray powder diffraction and Raman scattering techniques up to 60 GPa. A structural phase transition from R-3 to I2/m structure was observed at around 20 GPa, indicating that increasing the pressure has a similar effect on PCTO as decreasing the temperature, i.e., promoting the distortion of the structure. No polar structure of PCTO has been observed in the applied pressure range. The present study provides a valuable information about the crystal structure evolution of double perovskites upon compression, and will benefit high-pressure syntheses of novel double perovskites in the future. 

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2019
Keywords
Double perovskite, Phase transition, High pressure, Raman spectroscopy, X-ray powder diffraction
National Category
Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-390373 (URN)10.1016/j.jallcom.2019.06.096 (DOI)000474352000039 ()
Funder
Swedish Research Council
Available from: 2019-08-12 Created: 2019-08-12 Last updated: 2019-11-25Bibliographically approved
3. Bandgap engineering in Mn3TeO6: giant irreversible bandgap reduction triggered by pressure
Open this publication in new window or tab >>Bandgap engineering in Mn3TeO6: giant irreversible bandgap reduction triggered by pressure
Show others...
2019 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 55, p. 12000-Article in journal (Refereed) Published
Abstract [en]

In this study, the bandgap energy of the multiferroic oxide Mn3TeO6 is successfully reduced by ∼39% from 3.15 eV to 1.86 eV, accompanied by a phase transition at high pressures. The high-pressure phase with smaller bandgap energy is quenchable to ambient conditions and represents a promising light-harvesting material for photovoltaic applications.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-395737 (URN)10.1039/C9CC04821A (DOI)
Available from: 2019-10-23 Created: 2019-10-23 Last updated: 2020-02-07Bibliographically approved
4. Lattice distortion-induced sluggish phasetransition in CoCrFeNixAl1-x (x = 0.5, 0.75) highentropyalloys at high pressures
Open this publication in new window or tab >>Lattice distortion-induced sluggish phasetransition in CoCrFeNixAl1-x (x = 0.5, 0.75) highentropyalloys at high pressures
2019 (English)In: High Pressure Research, ISSN 0895-7959, E-ISSN 1477-2299, Vol. 39, no 4Article in journal (Refereed) Published
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:uu:diva-395736 (URN)10.1080/08957959.2019.1653865 (DOI)
Available from: 2019-10-23 Created: 2019-10-23 Last updated: 2020-02-18Bibliographically approved
5. Pressure-induced magnetovolume effect in CoCrFeAl high-entropy alloy
Open this publication in new window or tab >>Pressure-induced magnetovolume effect in CoCrFeAl high-entropy alloy
Show others...
2019 (English)In: Communications Physics, E-ISSN 2399-3650, Vol. 2, article id 42Article in journal (Refereed) Published
Abstract [en]

High-entropy alloys (HEAs) composed of multiple-principal elements with (nearly) equimolar ratio establish a new conceptual framework for alloy design and hold a promise for extensive applications in industry, akin to the controlled expansion alloys (CEAs), such as Invar alloys. Spontaneously, one question emerges - would it be possible to synthesize a novel class of alloys combining the virtues of both CEAs and HEAs? Here, we report the pressure-induced magnetovolume effect in the body-centered-cubic CoCrFeAl HEA coupled with magnetic phase transitions from ferromagnetic to paramagnetic, and to non-magnetic states, originating from the successive collapses of local magnetic moments of Co and Fe. The observed magnetovolume anomalies, occurring in a progressive way, tailor appreciably the coefficient of thermal expansion of CoCrFeAl. These results further strengthen HEAs’ anticipated potential for designing multifunctional materials in virtue of their multiple outstanding properties, and reveal possible routes for their future synthesis.

National Category
Condensed Matter Physics Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-382796 (URN)10.1038/s42005-019-0141-9 (DOI)000467220700001 ()
Available from: 2019-05-03 Created: 2019-05-03 Last updated: 2019-11-25Bibliographically approved

Open Access in DiVA

fulltext(1737 kB)49 downloads
File information
File name FULLTEXT01.pdfFile size 1737 kBChecksum SHA-512
c0b765a74494c8a916e50b7ce3b22c6c14164bbb8a305ccfc675b2df6d9fd499b6acfe5f558ae8d680f12a85ad6eb9e78c1316d09e9262025e1ce0c7727eb179
Type fulltextMimetype application/pdf
Buy this publication >>

Authority records BETA

Liu, Lei

Search in DiVA

By author/editor
Liu, Lei
By organisation
Mineralogy Petrology and Tectonics
Geosciences, Multidisciplinary

Search outside of DiVA

GoogleGoogle Scholar
Total: 49 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 589 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf