Magnetism and conductivity of silicides Y/sub 2/Mn/sub 3/Si/sub 5/ and Lu/sub 2/Mn/sub 3/Si/sub 5/

Y/sub 2/Mn/sub 3/Si/sub 5/ and Lu/sub 2/Mn/sub 3/Si/sub 5/ order ferrimagnetically at T /SUB N/ = 96 and 56 K respectively; their resistivity strongly decreases at the transition from paramagnetic to ferrimagnetic phase. A model is proposed for the magnetic coupling. Two new silicides with the Sc/sub 2/Fe/sub 3/Si/sub 5/-type structure are characterized by X-ray powder diffraction: Gd/sub 2/Mn/sub 3/Si/sub 5/ and Yb/sub 2/Mn/sub 3/Si/sub 5/