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Ernst WE, Lasserus M, Knez D, Hofer F, Hauser AW. Mixed-metal nanoparticles: phase transitions and diffusion in Au-VO clusters. Faraday Discuss 2023; 242:160-173. [PMID: 36178317 PMCID: PMC9890498 DOI: 10.1039/d2fd00089j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Nanoparticles with diameters in the range of a few nanometers, consisting of gold and vanadium oxide, are synthesized by sequential doping of cold helium droplets in a molecular beam apparatus and deposited on solid carbon substrates. After surface deposition, the samples are removed and various measurement techniques are applied to characterize the created particles: scanning transmission electron microscopy (STEM) at atomic resolution, temperature dependent STEM and TEM up to 650 °C, energy-dispersive X-ray spectroscopy (EDXS) and electron energy loss spectroscopy (EELS). In previous experiments we have shown that pure V2O5 nanoparticles can be generated by sublimation from the bulk and deposited without affecting their original stoichiometry. Interestingly, our follow-up attempts to create Au@V2O5 core@shell particles do not yield the expected encapsulated structure. Instead, Janus particles of Au and V2O5 with diameters between 10 and 20 nm are identified after deposition. At the interface of the Au and the V2O5 parts we observe an epitaxial-like growth of the vanadium oxide next to the Au structure. To test the temperature stability of these Janus-type particles, the samples are heated in situ during the STEM measurements from room temperature up to 650 °C, where a reduction from V2O5 to V2O3 is followed by a restructuring of the gold atoms to form a Wulff-shaped cluster layer. The temperature dependent dynamic interplay between gold and vanadium oxide in structures of only a few nanometer size is the central topic of this contribution to the Faraday Discussion.
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Affiliation(s)
- Wolfgang E. Ernst
- Institute of Experimental Physics, Graz University of TechnologyGrazAustria
| | | | - Daniel Knez
- Institute for Electron Microscopy and Nanoanalysis, Graz University of TechnologyGrazAustria
| | - Ferdinand Hofer
- Institute for Electron Microscopy and Nanoanalysis, Graz University of TechnologyGrazAustria
| | - Andreas W. Hauser
- Institute of Experimental Physics, Graz University of TechnologyGrazAustria
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Affiliation(s)
| | - Mohan Muralikrishna Garlapati
- Institut für Materialphysik Westfälische Wilhelms‐Universität Münster 48149 Germany
- Department of Metallurgical and Materials Engineering Indian Institute of Technology Madras Chennai 600036 India
| | - Sven Hilke
- Institut für Materialphysik Westfälische Wilhelms‐Universität Münster 48149 Germany
| | - Gerhard Wilde
- Institut für Materialphysik Westfälische Wilhelms‐Universität Münster 48149 Germany
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Sreedhara MB, Ghatak J, Bharath B, Rao CNR. Atomic Layer Deposition of Ultrathin Crystalline Epitaxial Films of V 2O 5. ACS Appl Mater Interfaces 2017; 9:3178-3185. [PMID: 28032979 DOI: 10.1021/acsami.6b14882] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Ultrathin epitaxial films (10-90 nm thick) of V2O5 have been grown on c-Al2O3 by atomic layer deposition using vanadyl acetylacetonate as the vanadium precursor along with oxygen plasma. Various process parameters have been optimized for the purpose, and excellent crystalline films could be obtained below 200 °C, without the need for post-heat treatment. With a moderate temperature window, the process yields a growth rate of 0.45 Å/cycle. The films have been characterized by electron microscopy, atomic force microscopy, Raman spectroscopy, and other means. The films exhibit a (001) preferred orientation with respect to c-Al2O3 and undergo compressive strain at the initial few monolayer growth to adjust epitaxially with the substrate. Heterojunction diodes based on TiO2(p)-(n)V2O5 as well as a humidity sensor have been fabricated using the V2O5 films.
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Affiliation(s)
- M B Sreedhara
- Chemistry and Physics of Materials Unit, New Chemistry Unit, International Centre for Materials Science and Sheikh Saqr Laboratory, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, P.O., Bengaluru 560064, India
| | - J Ghatak
- Chemistry and Physics of Materials Unit, New Chemistry Unit, International Centre for Materials Science and Sheikh Saqr Laboratory, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, P.O., Bengaluru 560064, India
| | - B Bharath
- Chemistry and Physics of Materials Unit, New Chemistry Unit, International Centre for Materials Science and Sheikh Saqr Laboratory, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, P.O., Bengaluru 560064, India
| | - C N R Rao
- Chemistry and Physics of Materials Unit, New Chemistry Unit, International Centre for Materials Science and Sheikh Saqr Laboratory, Jawaharlal Nehru Centre for Advanced Scientific Research , Jakkur, P.O., Bengaluru 560064, India
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Affiliation(s)
- Dang Sheng Su
- †Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China.,‡Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany
| | - Bingsen Zhang
- †Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China
| | - Robert Schlögl
- ‡Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany
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Goode AE, Porter AE, Ryan MP, McComb DW. Correlative electron and X-ray microscopy: probing chemistry and bonding with high spatial resolution. Nanoscale 2015; 7:1534-1548. [PMID: 25532909 DOI: 10.1039/c4nr05922k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Two powerful and complementary techniques for chemical characterisation of nanoscale systems are electron energy-loss spectroscopy in the scanning transmission electron microscope, and X-ray absorption spectroscopy in the scanning transmission X-ray microscope. A correlative approach to spectro-microscopy may not only bridge the gaps in spatial and spectral resolution which exist between the two instruments, but also offer unique opportunities for nanoscale characterisation. This review will discuss the similarities of the two spectroscopy techniques and the state of the art for each microscope. Case studies have been selected to illustrate the benefits and limitations of correlative electron and X-ray microscopy techniques. In situ techniques and radiation damage are also discussed.
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Affiliation(s)
- Angela E Goode
- Department of Materials, Imperial College London, London SW7 2AZ, UK.
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La Pierre HS, Minasian SG, Abubekerov M, Kozimor SA, Shuh DK, Tyliszczak T, Arnold J, Bergman RG, Toste FD. Vanadium Bisimide Bonding Investigated by X-ray Crystallography, 51V and 13C Nuclear Magnetic Resonance Spectroscopy, and V L3,2-Edge X-ray Absorption Near-Edge Structure Spectroscopy. Inorg Chem 2013; 52:11650-60. [DOI: 10.1021/ic4020543] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Henry S. La Pierre
- Department
of Chemistry, University of California, Berkeley, California 94720-1460, United States
| | - Stefan G. Minasian
- Inorganic,
Isotope and Actinide Chemistry, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
- Chemical
Sciences Division and Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Mark Abubekerov
- Department
of Chemistry, University of California, Berkeley, California 94720-1460, United States
| | - Stosh A. Kozimor
- Inorganic,
Isotope and Actinide Chemistry, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - David K. Shuh
- Chemical
Sciences Division and Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Tolek Tyliszczak
- Chemical
Sciences Division and Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - John Arnold
- Department
of Chemistry, University of California, Berkeley, California 94720-1460, United States
| | - Robert G. Bergman
- Department
of Chemistry, University of California, Berkeley, California 94720-1460, United States
| | - F. Dean Toste
- Department
of Chemistry, University of California, Berkeley, California 94720-1460, United States
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Fronzoni G, De Francesco R, Stener M. L2,3 edge photoabsorption spectra of bulk V2O5: A two components relativistic time dependent density functional theory description with finite cluster model. J Chem Phys 2012; 137:224308. [DOI: 10.1063/1.4769789] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Gubbens A, Barfels M, Trevor C, Twesten R, Mooney P, Thomas P, Menon N, Kraus B, Mao C, Mcginn B. The GIF Quantum, a next generation post-column imaging energy filter. Ultramicroscopy 2010; 110:962-70. [DOI: 10.1016/j.ultramic.2010.01.009] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Krivanek OL, Ursin JP, Bacon NJ, Corbin GJ, Dellby N, Hrncirik P, Murfitt MF, Own CS, Szilagyi ZS. High-energy-resolution monochromator for aberration-corrected scanning transmission electron microscopy/electron energy-loss spectroscopy. Philos Trans A Math Phys Eng Sci 2009; 367:3683-3697. [PMID: 19687060 DOI: 10.1098/rsta.2009.0087] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
An all-magnetic monochromator/spectrometer system for sub-30 meV energy-resolution electron energy-loss spectroscopy in the scanning transmission electron microscope is described. It will link the energy being selected by the monochromator to the energy being analysed by the spectrometer, without resorting to decelerating the electron beam. This will allow it to attain spectral energy stability comparable to systems using monochromators and spectrometers that are raised to near the high voltage of the instrument. It will also be able to correct the chromatic aberration of the probe-forming column. It should be able to provide variable energy resolution down to approximately 10 meV and spatial resolution less than 1 A.
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Abstract
In the electron microscope, spectroscopic signals such as the characteristic X-rays or the energy loss of the incident beam can provide an analysis of the local composition or electronic structure. Recent improvements in the energy resolution and sensitivity of electron spectrometers have improved the quality of spectra that can be obtained. Concurrently, the calculations used to simulate and interpret spectra have made major advances. These developments will be briefly reviewed. In recent years, the focus of analytical electron microscopy has moved away from single spectrum acquisition to mapping and imaging. In particular, the use of spectrum imaging (SI), where a full spectrum is acquired and stored at each pixel in the image is becoming widespread. A challenge for the application of spectrum imaging is the processing of such large datasets in order to extract the significant information. When we go beyond the mapping of composition and look to map bonding and electronic structure this becomes both more important and more difficult. Approaches to processing spectrum imaging data sets acquired using electron energy loss spectroscopy (EELS) will be explored in this paper.
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Affiliation(s)
- V J Keast
- School of Mathematical and Physical Science, The University of Newcastle, Callaghan, New South Wales, Australia.
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Abstract
The Wien2k code is widely used for the calculation of electron energy loss spectra. Low loss spectra can be calculated with the OPTIC package while core loss spectra are calculated with the TELNES program. A new version, TELNES.2, takes into account the effects of relativity for anisotropic materials. In this paper we discuss the effects of different parameters used for the self-consistent calculation of the electron density on the obtained spectra. We give an overview of possibilities for the calculation of complicated systems requiring a super-cell, like defects or disordered systems. We discuss the problem of the core hole and of the calculation of orientation-sensitive spectra and give an overview of results already published.
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Affiliation(s)
- C Hébert
- Institut für Festkörperphysik, Technische Universität Wien, A-1040 Wien, Austria.
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Khan I, Cunningham D, Lazar S, Graham D, Smith WE, McComb DW. A TEM and electron energy loss spectroscopy (EELS) investigation of active and inactive silver particles for surface enhanced resonance Raman spectroscopy (SERRS). Faraday Discuss 2006; 132:171-8; discussion 227-47. [PMID: 16833115 DOI: 10.1039/b506644a] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A number of silver particles and aggregates of particles were studied using surface enhanced resonance Raman spectroscopy (SERRS), high resolution transmission electron microscopy (HRTEM) and electron energy-loss spectroscopy (EELS). The SERRS mapping/TEM collage method developed previously in our group allows each SERRS active or inactive species to be reliably identified and analysed by each of the techniques in three different instruments. Our aim is to correlate SERRS activity, particle microstructure, chemical composition and electronic properties of each species to gain an insight into the enhancement mechanism. To date, our findings do not reveal any clear link between particle microstructure and SERRS activity. Additionally, the direction of the polarisation of the incident excitation or the presence of interparticle junctions between aggregated particles was not correlated with SERRS activity. However, spectral variations in the EELS data from structurally similar particles and SERRS active and inactive particles suggest that each species is chemically/electronically distinct. Differences in the spectra of single particles, dimers and clusters were also observed. Further analysis of the data, including extraction of the complex dielectric function from the EELS data, will provide an insight into the relationship between these observations and SERRS activity.
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Affiliation(s)
- Imran Khan
- Department of Materials, Imperial College London, London, UK.
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De Francesco R, Stener M, Causà M, Toffoli D, Fronzoni G. Time dependent density functional investigation of the near-edge absorption spectra of V2O5. Phys Chem Chem Phys 2006; 8:4300-10. [PMID: 16986073 DOI: 10.1039/b607705f] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have performed Time Dependent Density Functional Theory (TDDFT) calculations employing a cluster model of the core excitation spectra of vanadium pentoxide, V(2)O(5). The excitation energies and dipole transition moments are determined for all the core edges, vanadium and oxygen K- and vanadium L-edges, treating them at the same level of accuracy. The agreement between the TDDFT theoretical spectra and the experimental data is rather good, particularly at the V and O K-edges. A quantitative reproduction of the fine pre-edge structures appears more difficult for the V L-edge. The comparison between the TDDFT results and the results obtained at the simpler one electron Kohn-Sham (KS) level indicates that the V and O K edges can be correctly described within a single particle approximation (KS), while the strong modification of the V L-edge structures from the KS to the TDDFT description emphasizes the importance of configuration mixing to treat the metal 2p excitations. The origin of the calculated pre-edge features is analyzed in detail with the help of the atom-projected density-of-states of the unoccupied levels. This analysis emphasizes the V 3d dominant character of the final states in the conduction band, probed by the V L-absorption. The strong octahedral distortion of the V(2)O(5) structure allows the mixing of the 3d state with the V 4p components, which are mapped by the oscillator strength in the V K-edge spectrum. The high intensity of the O 1s transitions reflects the presence of a significant O 2p component in the conduction band.
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Affiliation(s)
- R De Francesco
- Dipartimento di Scienze Chimiche, Via L. Giorgieri 1, Università di Trieste, I-34127 Trieste, Italy
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Mark Rainforth W. Recent Developments in the Microscopy of Ceramics. Elsevier; 2004. pp. 167-246. [DOI: 10.1016/s1076-5670(04)32004-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Su DS, Hébert C, Willinger M, Schlögl R. Anisotropy and collection angle dependence of the oxygen K ELNES in V2O5: a band-structure calculation study. Micron 2003; 34:227-33. [PMID: 12895494 DOI: 10.1016/s0968-4328(03)00031-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We present a theoretical study of the anisotropy and collection angle dependence of the oxygen K ELNES in V2O5. Ab initio band-structure calculations were performed with WIEN97, a program package based on the full potential linearised augmented plane waves (FP-LAPW) method. An analysis of the site and angular momentum projected DOS allowed the identification of differently coordinated oxygens and the separation of the oxygen K-edge into contributions from terminal (vanadyl) oxygens, bridging oxygens and chain oxygens. The major contribution to the anisotropy of the O K-edge ELNES could be assigned to transitions at the vanadyl oxygen. Theoretical calculations predict that the extent of changes in the ELNES would be large enough for detection in collection angle dependent O K-edge measurements. A variation in the fine structure of the O K-edge with decreasing collection angle was confirmed by experiments.
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Affiliation(s)
- D S Su
- Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, D-14195 Berlin, Germany.
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