• Crystal-clear - The '2014 Most Superlative Crystal Growth Contest' for School Classes
    D. Perret, H. Hagemann, R. Cerny, C. Renner, E. Giannini, L. Guénée, C. Besnard, D. Gérard and L. Windels
    Chimia, 68 (12) (2014), p893-895
    DOI:10.2533/chimia.2014.893 | unige:46708 | Article PDF
 
To celebrate the International Year of Crystallography among the general public, a consortium of chemists, physicists and crystallographers of the University of Geneva organised in Spring 2014 an incentive crystal growth contest for Geneva scholars aged 4 to 19. Starting from a kit containing a salt and user instructions, classes had to prepare a crystal that met specific criteria according to their category of age. The composition of the salt – potassium dihydrogen phosphate (KDP) – was only disclosed to the participants during the final Awards Ceremony. This contest positively exceeded our expectations with almost 100 participating classes (ca. 1800 participants) and 54 specimens received over all categories.
  • Anisotropic magnetic, transport and thermodynamic properties of novel tetragonal Ce2RhGa12 compound
    S. Nallamuthu, T.P. Rashid, V. Krishnakumar, C. Besnard, H. Hagemann, M. Reiffers and R. Nagalakshmi
    Journal of Alloys and Compounds, 604 (2014), p379-383
    DOI:10.1016/j.jallcom.2014.03.067 | unige:37941 | Article HTML
We report on a comprehensive study of the magnetization, resistivity and heat capacity on the single crystals of Ce2RhGa12 synthesized using Ga flux. Single crystal X-ray diffraction data confirm the tetragonal Pb/nbm structure of Ce2RhGa12, which is isostructural to Ce2PdGa12. Ce2RhGa12 orders antiferromagnetically at TN = 3.5 K and exhibits anisotropic magnetic behavior, inferred from the magnetization and resistivity data, taken along the two principal crystallographic directions of the crystal, viz., along [100] and [001]. The anisotropic magnetic response of Ce2RhGa12 establishes [001] as the easy axis of magnetization, and a weak meta-magnetic transition is also observed in the magnetic isotherm at 2K along the same axis. A sharp peak in specific heat signals the bulk antiferromagnetic transition at TN = 3.5 K, which shifts to lower temperatures in low applied fields. The electrical resistivity along the two directions shows metallic behavior from 300K down to 1.8K and establishes Ce2RhGa12 as a normal, trivalent cerium compound.
  • Crystal growth and structure determination of the novel tetragonal compound Ce2RhGa12
    R. Nagalakshmi, R. Kulkarni, S.K. Dhar, A. Thamizhavel, V. Krishnakumar, C. Besnard, H. Hagemann and M. Reiffers
    Chemistry of metals and alloys, 4 (3/4) (2011), p229-233
    unige:23118 | Abstract | Article PDF
Single crystals of Ce2RhGa12 have been synthesized using Ga flux and their structure was determined by single-crystal X-ray diffraction. Ce2RhGa12 crystallizes in the tetragonal space group P4/nbm (No. 125), and is isostructural to Ce2PdGa12, with Z = 2 and lattice parameters a = 6.0405 Å and c = 15.706 Å. Data were collected at the Swiss Norwegian Beam Line at the European Synchrotron Facility, Grenoble, France. Laue diffraction was carried out to confirm the quality of the single crystal and showed well-defined spots and tetragonal symmetry.

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