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Marshall KP, Eidem SO, Småbråten DR, Selbach SM, Grande T, Einarsrud MA. Hydrothermal synthesis of hexagonal YMnO 3 and YbMnO 3 below 250 °C. Dalton Trans 2021; 50:9904-9913. [PMID: 34212164 DOI: 10.1039/d1dt01572a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The hydrothermal synthesis of hexagonal YMnO3 and YbMnO3 are reported using high KOH mineraliser concentrations (>10 M) and low temperatures (<240 °C). The relation between reaction parameters and resulting phase purity were mapped by ex situ and in situ X-ray diffraction. Excess Y2O3 resulted in two-phase product with hexagonal YMnO3 with different lattice parameters. An unusual microstructure was observed in which particles have a hexagonal shape with a highly crystalline edge and either a hollow or polycrystalline interior. An Ostwald ripening mechanism was proposed to explain this phenomenon. Solid-state reactions and density functional theory calculations were performed to determine plausible defect chemistry which can lead to the observed phases with different lattice parameters.
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Affiliation(s)
- Kenneth P Marshall
- Department of Materials Science, Norwegian University of Science and Technology, Trondheim, Norway.
| | - Sigurd O Eidem
- Department of Materials Science, Norwegian University of Science and Technology, Trondheim, Norway.
| | - Didrik R Småbråten
- Department of Materials Science, Norwegian University of Science and Technology, Trondheim, Norway.
| | - Sverre M Selbach
- Department of Materials Science, Norwegian University of Science and Technology, Trondheim, Norway.
| | - Tor Grande
- Department of Materials Science, Norwegian University of Science and Technology, Trondheim, Norway.
| | - Mari-Ann Einarsrud
- Department of Materials Science, Norwegian University of Science and Technology, Trondheim, Norway.
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Grendal OG, Nylund IE, Blichfeld AB, Tominaka S, Ohara K, Selbach SM, Grande T, Einarsrud MA. Controlled Growth of Sr x Ba 1-x Nb 2 O 6 Hopper- and Cube-Shaped Nanostructures by Hydrothermal Synthesis. Chemistry 2020; 26:9348-9355. [PMID: 32125026 PMCID: PMC7496942 DOI: 10.1002/chem.202000373] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Indexed: 12/05/2022]
Abstract
Controlling the shape and size of nanostructured materials has been a topic of interest in the field of material science for decades. In this work, the ferroelectric material Srx Ba1-x Nb2 O6 (x=0.32-0.82, SBN) was prepared by hydrothermal synthesis, and the morphology is controllably changed from cube-shaped to hollow-ended structures based on a fundamental understanding of the precursor chemistry. Synchrotron X-ray total scattering and PDF analysis was used to reveal the structure of the Nb-acid precursor, showing Lindqvist-like motifs. The changing growth mechanism, from layer-by-layer growth forming cubes to hopper-growth giving hollow-ended structures, is attributed to differences in supersaturation. Transmission electron microscopy revealed an inhomogeneous composition along the length of the hollow-ended particles, which is explained by preferential formation of the high entropy composition, SBN33, at the initial stages of particle nucleation and growth.
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Affiliation(s)
- Ola G Grendal
- Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, Sem Saelands vei 12, 7491, Trondheim, Norway
| | - Inger-Emma Nylund
- Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, Sem Saelands vei 12, 7491, Trondheim, Norway
| | - Anders B Blichfeld
- Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, Sem Saelands vei 12, 7491, Trondheim, Norway
| | - Satoshi Tominaka
- International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki, 305-0044, Japan
| | - Koji Ohara
- Diffraction and Scattering Division, Center for Synchrotron Radiation Research, Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-gun, Hyogo, 679-5198, Japan
| | - Sverre M Selbach
- Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, Sem Saelands vei 12, 7491, Trondheim, Norway
| | - Tor Grande
- Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, Sem Saelands vei 12, 7491, Trondheim, Norway
| | - Mari-Ann Einarsrud
- Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, Sem Saelands vei 12, 7491, Trondheim, Norway
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Marshall KP, Blichfeld AB, Skjaervø SL, Grendal OG, van Beek W, Selbach SM, Grande T, Einarsrud MA. A Fast, Low-Temperature Synthesis Method for Hexagonal YMnO 3 : Kinetics, Purity, Size and Shape as Studied by In Situ X-ray Diffraction. Chemistry 2020; 26:9330-9337. [PMID: 32129543 PMCID: PMC7497076 DOI: 10.1002/chem.202000528] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Indexed: 11/07/2022]
Abstract
The reaction mechanisms, phase development and kinetics of the hydrothermal synthesis of hexagonal-YMnO3 from Y2 O3 and Mn2 O3 using in situ X-ray diffraction are reported under different reaction conditions with temperatures ranging from 300 to 350 °C, and using 1, 5 and 10 m KOH, and 5 m NaOH mineraliser. Reactions initiated with Y2 O3 hydrating to Y(OH)3 , which then dehydrated to YO(OH). Higher temperatures and KOH concentrations led to faster, more complete dehydrations. However, 1 m KOH led to YO(OH) forming concurrently with Y(OH)3 before Y(OH)3 fully dehydrated but yielded a very low phase purity of hexagonal-YMnO3 . Using NaOH mineraliser, no YO(OH) was observed. Dehydration also initiated at a higher temperature in the absence of Mn2 O3 . The evolution of Rietveld refined scale factors was used to determine kinetic information and approximate activation energies for the reaction. The described hydrothermal synthesis offers a fast, low-temperature method for producing anisometric h-YMnO3 particles.
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Affiliation(s)
- Kenneth P Marshall
- Department of Materials Science and Engineering, NTNU-Norwegian University of Science and Technology, Sem Saelands vei 12, 7034, Trondheim, Norway
| | - Anders B Blichfeld
- Department of Materials Science and Engineering, NTNU-Norwegian University of Science and Technology, Sem Saelands vei 12, 7034, Trondheim, Norway
| | - Susanne L Skjaervø
- Department of Materials Science and Engineering, NTNU-Norwegian University of Science and Technology, Sem Saelands vei 12, 7034, Trondheim, Norway
| | - Ola G Grendal
- Department of Materials Science and Engineering, NTNU-Norwegian University of Science and Technology, Sem Saelands vei 12, 7034, Trondheim, Norway
| | - Wouter van Beek
- Swiss-Norwegian Beamlines, European Synchrotron Radiation Facility, 71 avenue des Martyrs, CS 40220, 38043, Grenoble Cedex 9, France
| | - Sverre M Selbach
- Department of Materials Science and Engineering, NTNU-Norwegian University of Science and Technology, Sem Saelands vei 12, 7034, Trondheim, Norway
| | - Tor Grande
- Department of Materials Science and Engineering, NTNU-Norwegian University of Science and Technology, Sem Saelands vei 12, 7034, Trondheim, Norway
| | - Mari-Ann Einarsrud
- Department of Materials Science and Engineering, NTNU-Norwegian University of Science and Technology, Sem Saelands vei 12, 7034, Trondheim, Norway
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