Magnetic and Electrical Properties of ${\hbox{Mn}}_{2 - {\rm x}}{\hbox{Ni}}_{1 + {\rm x}}{\hbox{Sb}}$

X-ray powder diffraction, magnetization and electrical resistivity measurements were carried out for polycrystalline Heusler alloys Mn 2-x Ni 1+x Sb ( 0 ≤ x ≤ 1) in 4.2-720 K and in magnetic fields up to 16 T. The lattice parameter a was determined to be 0.5974 nm for Mn 2 NiSb (x = 0) and 0.6021 nm for MnNi 2 Sb (x = 1) at room temperature. The parameter a shrinks for 0.4 ≤ x ≤ 0.75. The Curie temperatures T C for x = 0 and 1 were determined to be 623 K and 353 K, respectively. For, T C was enhanced up to 663 K (x = 0.5). Obtained results showed the unique behaviors on the structural, magnetic and electrical properties for the intermediate Mn-Ni composition.