Structure and Magnetic Properties of RIn2.9Co0.1 (R = La, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, Tm, Lu)

RIn2.9Co0.1 (R = rare earth) intermetallic compound has been synthesized, and its structure and magnetic properties have been investigated using X-ray diffraction, scanning electron microscopy with energy dispersive spectrum and magnetic measurement. RIn2.9Co0.1 crystallizes in cubic AuCu3-type structure for R = heavy rare earths, and a small amount of R(In, Co)(2) metaphase separates from RIn2.9Co0.1 for R = light rare earth. Rietveld's structural refinement confirms that R(In, Co)(2) metaphase is the isomorphism of hexagonal CaIn2. The lattice parameters of RIn2.9Co0.1 tend to decrease with increasing atomic number of R due to the shrinking effect of atomic radius in rare earth group. The cubic phase can be stabilized in the range of 1.048-1.133 for the effective atomic radius ratio R-A and 0.35-0.41 for the electronegativity difference Delta X. The magnetizing process of RIn2.9Co0.1 shows various characteristics with increasing atomic number of rare earth, and the magnetizing curves follow a ferromagnetic model for R = La, a mixed ferromagnetic and paramagnetic model for R = Ce, Pr, Nd, Gd, Tb, Dy. The formation of ferromagnetic characteristics results from the strong spin-spin interaction between R and Co.