A new ternary carbide Dy2Mn2−xC5 (x=0.6): Preparation, crystal structure, and physical properties

Abstract

The crystal structure, magnetic and electrical transport properties of the new ternary compound Dy2Mn2−xC5 (x=0.6) have been investigated. According to X-ray powder diffraction the carbide crystallizes in its own structure type, space group I4/mmm, a=3.6421(2), c=15.7713(9) Å, RB=0.062, Rp=0.134. The crystal structure contains isolated carbon atoms and C2 dimers in square-bipyramidal holes and distorted bicapped square anti-prisms, respectively. Manganese atomic positions in the structure were found to be not fully occupied. Physical properties were studied in the temperature range down to 0.4K. The electrical resistivity of Dy2Mn2−xC5 (x=0.6) reveals its basically metallic nature with a positive temperature coefficient above about 30K. A resistive anomaly at around 20K indicates the appearance of an antiferromagnetic superzone boundary gap at low temperatures. A phase transition towards long range antiferromagnetic magnetic ordering below 19K is further revealed by heat capacity and ac susceptibility data. Magnetization data refer to a non-trivial nature of the magnetic ground state which may be caused by the intrinsic structural disorder associated with random vacancies at the Mn site.