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-xNi_1+xSb ( 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 Mn₂NiSb (x = 0) and 0.6021 nm for MnNi₂Sb (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.