First single crystal of pure trivalent Co oxidation state material

Single Crystal Growth of Pure Co3+ Oxidation State Material LaSrCoO4

Successful growth of large high-quality LaSrCoO4 single crystals was recently performed and reported by the crystal growth group from Max-Planck-Institute for Chemical Physics of Solids, lead by Alexander Christoph Komarek. In the emerging open access crystallography journal “Crystals” the autors write that obtaining large, impurity-free single crystals was only possible using the high O2-pressure floating zone technique with pure oxygen at 150 bar in a ScIDre HKZ furnace. Growth speed of 2 mm/h reqiured stable conditions. Black shiny single crystals of ∼60 mm length were obtained. No impurity phase could be detected in XRD and magnetic susceptibility measurements, and there are almost no Co2+ impurities visible in the synchrotron X-ray absorbtion spectroscopy spectra.

So far, this is the first succesful attempt to grow sizeable single crystals with apparently big population of the Co3+ high-spin state, which are suitable for detailed inelastic neutron scattering experiments of pure Co3+ oxidation states. The recent measurements of the Max-Planck group of Alexander Komarek indicate a spin-glass transition in LaSrCoO4, which is related to Co3+ ions in the high-spin state.