Name: Wilfried Hermes
Diploma / M.Sc degree: Westfälische Wilhelms-Universität Münster, Germany
(February 2007)

PhD Project: Magnetism and hydrogenation behaviour of intermetallic cerium compounds

Abstract of Research Project

My PhD project is interdisciplinary arranged between the working group of Prof. Dr. R. Pöttgen and Dr. B. Chevalier (ICMCB-CNRS, Bordeaux).

In this research project, the focus will lie on the characterization by X-ray powder and single crystal diffraction, the magnetic properties and the hydrogenation behaviour of CeTX-compounds (T = late transition metal; X = element of the 3rd, 4th, or 5th main group). These compounds have intensively been studied in recent years with respect to their interesting structural and physical properties. Depending on the T and X components and the local cerium coordination, the Ce 4f orbitals show different hybridization, leading to manifold, highly interesting magnetic and electrical properties such as intermediate valence characteristics, antiferromagnetism, ferromagnetism, superconductivity, Kondo- or heavy fermion-type behaviour.

The structural and magnetic properties of the CeTX compounds can be changed through application of high pressure or via hydrogenation. In the latter case hydrogen insertion leads to a volume increase and in many cases, hydrogenation leads to a reduction in the cerium valence from intermediate values to pure trivalent cerium. Recent examples are CeNiAl, CeNiGa and CeRhSb.


Publications

W. Hermes, U C. Rodewald, B. Chevalier, S. F. Matar, V. Eyert, R. Pöttgen
The plumbide CeZnPb - Structure, magnetism, and chemical bonding
Solid State Sci. 12(5) (2010), 929-937.

T. Harmening, W. Hermes, M. Eul, R. Pöttgen
Mixed valent stannide EuRuSn3 - Structure, magnetic properties, and Moessbauer spectroscopic investigation
Solid State Sci. 12(2) (2010), 284-290.

I. Schellenberg, M. Eul, W. Hermes, R. Pöttgen
A 121Sb and 151Eu Moessbauer Spectroscopic Investigation of EuMn2Sb2, EuZn2Sb2, YbMn2Sb2, and YbZn2Sb2
Z. Anorg. Allg. Chem. 636(1) (2010), 85-93.

W. Hermes, S. F. Matar, R. Pöttgen
Unusually short Ce-Ru distances in CeRuAl and related compounds
Z. Naturforsch. 64B (2009), 901-908.

F. Tappe, W. Hermes, M. Eul, R. Pöttgen
Mixed cerium valence and unusual Ce-Ru bonding in Ce23Ru7Cd4
Intermetallics 17(12) (2009), 1035-1040.

S. Linsinger, W. Hermes, B. Chevalier, S. Couillaud, J.-L. Bobet, M. Eul, R. Pöttgen
Transition from antiferromagnetic ordering to cluster-glass behavior in the solid solution Gd4NiMg1-xAlx (0= x =0.9)
Intermetallics 17(12) (2009), 1028-1034.

T. Harmening, W. Hermes, M. Eul, F. M. Schappacher, R. Pöttgen
Structure and properties of Eu2Pt3Sn5
Z. Kristallogr. 224(7) (2009), 351-357.

E. Gaudin, B. Chevalier, W. Hermes, U. C. Rodewald, R. Pöttgen
Structure, magnetic and electrical properties of CeIrSb and its hydride CeIrSbH0.8
J. Solid State Chem. 182(7) (2009), 1827-1832.

W. Hermes, T. Harmening, R. Pöttgen
Ferromagnetism and Magnetocaloric Effect around 95 K in the Laves Phase EuRh1.2Zn0.8
Chem. Mater. 21(14) (2009), 3325-3331.

W. Hermes, R. Pöttgen
Magnetic ordering in CeZnGe
Z. Naturforsch. 64B (2009), 361-364.

F. Tappe, F. M. Schappacher, W. Hermes, M. Eul, R. Pöttgen
Drastic decrease of the Curie temperature in the solid solution GdRuxCd1-x
Z. Naturforsch. 64B (2009), 356-360.

W. Hermes, S. F. Matar, T. Harmening, U. C. Rodewald, M. Eul, R. Pöttgen
Ferromagnetic ordering in CeZnSn
Z. Naturforsch. 64B (2009), 175-183.

B. Heying, U. C. Rodewald, W. Hermes, R. Pöttgen
Structure and magnetic properties of GdPt2In and GdPt2Sn
Z. Naturforsch. 64B (2009), 170-174.

W. Hermes, R. Pöttgen
RERhZn (RE=Y, Sm, Gd-Lu) compounds with TiNiSi type structure - Synthesis and magnetic properties
Solid State Sci. 11(3) (2009), 706-713.

M. Rotter, M. Tegel, D. Johrendt, I. Schellenberg, W. Hermes, R. P&oouml;ttgen
Spin Density Wave Anomaly at 140 K in the Ternary Arsenide BaFe₂As₂
Phys. Rev. B 78 (2008), 020503 (4 p).

B. Heying, u. Ch. Rodewald, G. Heymann, W. Hermes, F. M. Schappacher, J. F. Riecken, C. P. Sebastian, H. Huppertz, R. Pöttgen
The High-temperature Modification of LuAgSn and High-pressure High-temperature Experiments on DyAgSn, HoAgSn, and YbAgSn
Z. Naturforsch. 63b (2008), 193.

R. Mishra, W. Hermes, U. Ch. Rodewald, R.-D. Hoffmann, R. Pöttgen
Trivalent-Intermediate Valent Cerium Ordering in Ce₂RuZn₄
Z. Anorg. Allg. Chem. 634 (2008), 470.

R. Mishra, W. Hermes, R. Pöttgen
Structure and Magnetic Properties of CePtZn
Z. Naturforsch. 62b (2007), 1581.


Publications of research conducted prior to GSC-MS membership

W. Hermes, U. Ch. Rodewald, B. Chevalier, R. Pöttgen
Structure Refinement of CePtSi and Hydrogenation Behaviour of CePdGe, CePtSi and CePdGe
Z. Naturforsch. 62b (2007), 613.

J. F. Riecken, W. Hermes, B. Chevalier, R.-D. Hoffmann, F. M. Schappacher, R. Pöttgen
Trivalent-Intermediate Valent Cerium Ordering in CeRuSn – A Static Intermediate Valent Cerium Compound with a Superstructure of the CeCoAl Type
Z. Anorg. Allg. Chem. 633 (2007), 1094.

W. Hermes, S. Rayaprol, R. Pöttgen
Magnetic Properties and Specfic Heat Studies of the Plumbides CeTPb (T = Cu, Pd, Ag, Au)
Z. Naturforsch. 62b (2007), 901.

I. R. Muts, F. M. Schappacher, W. Hermes, V. I. Zaremba, R. Pöttgen
Synthesis, structure and properties of SrAu₃In₃ and EuAu₃In₃ – New indides with gold zig-zag chains
J. Solid State Chem. 180 (2007), 2202.

W. Hermes, U. Ch. Rodewald, B. Chevalier, R. Pöttgen
Hydrogenation of the Kondo compound CePtIn
Solid State Sci. 9 (2007), 874.

I. R. Muts, V. I. Zaremba, U. Ch. Rodewald, W. Hermes, R. Pöttgen
Ca₂Pd₂In and Ca₂Pt₂In with Monoclinic HT-Pr₂Co₂Al Type Structure
Z. Anorg. Allg. Chem. 633 (2007), 2725.


Wilfried Hermes
eMail: Wilfried Hermes