Hoch- und Tieftemperatur Ramanspektrometer
Zusammenfassung der Projektergebnisse
1. Metastable and stable mullite-type Al18B4O33 and Al4B2O9 are of particular interests due to their thermos-elastic properties. Raman spectra provided the finger print signature with respect to their different coordination. Raman frequency shift and linewidth were monitored for a wide temperature range, extracting rigid and disordered borates, anharmonicity and grain-size effects. 2. PbMBO4 (M = Al, Ga, Mn, Fe and Cr) compounds have been drawn attention due to their diverse crystal chemical aspects, magnetic property, axial negative thermal expansion, strong local asymmetry commenced from the stereo-chemically active lone electron pair (LEP) effect of Pb2+. Beside the crystal chemistry in the end-members and their solid solutions, phonon-phonon, spin-phonon interactions were studied using temperature-dependent Raman spectroscopy. 3. Crystal chemical investigations were carried out on mullite-type Bi2M4O9/10 systems. The nano-particles, polycrystalline and the single crystals were investigated. A combined study between Raman and FTIR can reveal the centrosymmetry and non-centrosymmetry of the crystals, the puzzling multi-ferroic behaviors of Bi2Fe4O9 and Bi2Mn4O10 are an on-going project to understand from the vibrational features. 4. Sodalite and cancrinite are two representative structures of the zeolite family, which represent classic host-guest chemistry. Raman spectroscopy provided complimentary information together with other advanced techniques for a qualitative origin of the host-guest interactions. Resonance Raman on Na6+x[AlSiO4]6(MnO4)x(H2O)8-4x was studied via temperature-dependent (TD) spectroscopy. The TD Raman indicated an increase of the anharmonicity of the template anion with decreasing temperature. The Raman study was also extended to follow different stacking sequences in CAN and SOD framework. Moreover, Raman spectra helped understand some intra-cage reaction mechanisms. 5. In search of narrow band-gap photo-catalysts with enhanced photocatalytic activity under visible light irradiation mullite-type Bi2M4O9/10 are under investigations to bridge a relation between phase composition, band-gap width and the highest possible photocatalytic activity. In this project Raman spectroscopy provides information to follow the structural characterization at non-ambient and ambient conditions for amorphous, nano and polycrystalline materials. 6. The photonic crystals (PhCs) of bismuth tungstates are under investigations to maximize the photocatalytic activity of the materials. Since infiltration of PhCs with desired materials can markedly increases the Raman scattering intensity, beside the routine collection of spectra, some weak Raman scatterers are under consideration to enhance the sensitivity for molecular analysis. Raman spectra were collected on nanometers to micron sized particles of bismuth tungstates before and after the production of inverse opal structures. 7. Three arsenotungstates systems Li3AsW7O25, Na[AsW2O9] and K[AsW2O9] were intensively studied using temperature-dependent Raman spectroscopy. Due to a high number of allowed Raman modes specific mode analyses was difficult due to merging. In this regard, the autocorrelation method provided a sensible way to analyze the subtle changes of the vibrational features between two cut-off frequencies. The slice of the optical frequency spectrum can be compared to the local phonon density of states of Kieffer model, however, not with uniform distribution of frequencies. 8. Intensive temperature-dependent Raman spectroscopy was studied in some alkali metal (LixWO3, NaxWO3 and KxWO3) bonze and bronzoid (KxVyW1-yO3 and KxTayW1-yO3) systems. Complementary Raman and X-ray diffraction helped elucidate the correct symmetry of the hexagonal K0.3 WO3 bronze. 9. Dealing with schafarzikites of composition AB2O4 (A = Zn2+, Cu2+, Fe2+ Pb4+, Sn4+ etc. and B = As3+, Sb3+, Pb2+, Sn2+ etc.)’ Raman spectra were collected on the single crystal. This research particularly emphasizes to understand the role of lone electron pairs.
Projektbezogene Publikationen (Auswahl)
- Anisotropic thermal expansion and anharmonic phonon behavior of mullite-type Bi2Ga4O9. Mat. Res. Bull. 48 (2013) 3284 – 3291
M. M. Murshed, Th. M. Gesing
- Structural properties of mullite-type Pb(Al 1-xMnx)BO4. Z. Kristallogr. 228 (2013) 532 – 543
Th. M. Gesing, C. B. Mendive, M. Curti, D. Hansmann, G. Nénert, P- E. Kalita, K. E. Linpinska, A. L. Cornelius, M. M. Murshed
- Synthesis, crystal structure and temperature-dependent behavior of gallogermanate tetrahydroborate sodalite |Na8(BH4)2|[GaGeO4]6. Micro. Meso. Mater. 174 (2013) 54 – 61
I. Poltz, L. Robben, J-Ch. Buhl, Th. M. Gesing
- Temperature-dependent framework-template interaction of |Na6(H2O)8|[ZnPO4]6 sodalite. J. Solid State Chem. 207 (2013) 13 – 20
L. Robben, Th. M. Gesing
- Anisotropic lattice thermal expansion of PbFeBO4: a study by X-ray and neutron diffraction, Raman spectroscopy and DFT calculations. Mat. Res. Bull. 59 (2014) 170 – 178
M. M. Murshed, C. B. Mendive, M. Curti, G. Nénert, P. E. Kalita, K. Lipinska, A. L. Cornelius, A. Huq, Th. M. Gesing
(Siehe online unter https://doi.org/10.1016/j.materresbull.2014.07.005) - High-Temperature Phase Transitions, Spectroscopic Properties and Dimensionality Reduction in Rubidium Thorium Molybdates Family. Inorg. Chem. 53 (2014) 3088 – 3098
B. Xiao, Th. M. Gesing, Ph. Kegler, G. Modolo, D. Bosbach, H. Schlenz, E. V. Suleimanov, E. V. Alekseev
(Siehe online unter https://doi.org/10.1021/ic403003f) - Morphotropy and temperature driven polymorphism in A2Th(AsO4)2 (A= Li, Na, K, Rb, Cs) series. Inorg. Chem. 53 (2014) 11231 – 11241
N. Yu, V. V. Klepov, D. Bosbach, E. V. Suleimanov, Th. M. Gesing, L. Robben, E. V. Alekseev
(Siehe online unter https://doi.org/10.1021/ic5018246) - Nanoporous gold supported ceria for the water gas shift reaction: UHV inspired design for applied catalysis. J. Phys. Chem. C 118 (2014) 29270 – 29277
J. Shi, A. Schaefer, A. Wichmann, M. M. Murshed, Th. M. Gesing, A. Wittstock, M. Bäumer
(Siehe online unter https://doi.org/10.1021/jp505433a) - Synthesis, crystal structure and temperature-dependent properties of gallogermanate nitrite sodalite |Na8(NO2)2|[GaGeO4]6. Micro. Meso. Mater. 203 (2014) 100 – 105
I. Poltz, L. Robben, J.-Ch. Buhl, Th. M. Gesing
(Siehe online unter https://doi.org/10.1016/j.micromeso.2014.10.007) - Synthesis, structure and properties of Na[AsW2O9]. Mat. Res. Bull. 60 (2014) 258 – 263
P. Zhao, M. M. Murshed, E. V. Alekseev, V. V. Atuchin, A. M. Pugachev, Th. M. Gesing
(Siehe online unter https://doi.org/10.1016/j.materresbull.2014.08.040) - Bi2Fe4O9: Structural changes from nano- to micro-crystalline state. Z. Naturforsch. B
A. Kirsch, M. M. Murshed, P. Gaczynski, K.-D. Becker, Th. M. Gesing
(Siehe online unter https://doi.org/10.1515/znb-2015-0227) - Dinuclear Face-Sharing Bioctahedral Tungsten(VI) Core and Unusual Thermal Behavior in Complex Th Tungstates. Chem. Eur. J. 21 (2015) 7746 – 7754
B. Xiao, Th. M. Gesing, L. Robben, D. Bosbach, E. V. Alekseev
(Siehe online unter https://doi.org/10.1002/chem.201500500) - Nanoscale building blocks in a novel lithium arsenotungsten bronze: synthesis and characterization J. Solid State Chem. 226 (2015) 81 – 87
P. Zhao, M. M. Murshed, A. Huq, H. K. Grossmann, L. Mädler, E. V. Alekseev, Th. M. Gesing
(Siehe online unter https://doi.org/10.1016/j.jssc.2015.02.009) - Thermal expansion of mullite-type Bi2Al4O9: a study by X-ray diffraction, vibrational spectroscopy and density functional theory. J. Solid State Chem. 229 (2015) 87 – 96
M. M. Murshed, C. B. Mendive, M. Curti, M. Šehović, A. Friedrich, M. Fischer, Th. M. Gesing
(Siehe online unter https://doi.org/10.1016/j.jssc.2015.05.010) - A versatile sol-gel coating for binary oxides on nanoporous gold and their application in the water gas shift reaction Catal. Sci. Tech.
J. Shi, V. Zieleasek, M. M. Murshed, Th. M. Gesing, M. Bäumer, A. Wittstock
(Siehe online unter https://doi.org/10.1039/C5CY02205C) - Giant Volume Change and Topological Gaps in Temperature and Pressure Induced Phase Transitions of ThMo2O8: An Experimental and Computational Study. Chem. Eur. J. 22 (2016) 946 – 958
B. Xia, P. Kegler, Th. M. Gesing, L. Robben, A. Blanca-Romero, P. Kowalski, Y. Li, V. Klepov, D. Bosbach, E. Alekseev
(Siehe online unter https://doi.org/10.1002/chem.201503839) - Tantalum and vanadium substitution in hexagonal K0.3WO3 bronze: synthesis and characterization. Z. Kristallogr. 321 (2016) 11 – 21
M. S. Rahman, M. M. Murshed, Th. M. Gesing
(Siehe online unter https://doi.org/10.1515/zkri-2015-0003)
