Abstract
We synthesized the Mn-doped Mg(In 2-x Mn x )O 4 oxides with 0.03{less-than or slanted equal to}x{less-than or slanted equal to}0.55 using a solid-state reaction method. The X-ray diffraction patterns of the samples were in a good agreement with that of a distorted orthorhombic spinel phase. Their lattice parameters and unit-cell volumes decrease with x due to the substitution of the smaller Mn 3+ ions to the larger In 3+ ions. The undoped MgIn 2 O 4 oxide presents diamagnetic signals for 5 K{less-than or slanted equal to}T{less-than or slanted equal to}300 K. The M(H) at T=300 K reveals a fairly negative-sloped linear relationship. Neither magnetic hysteresis nor saturation behavior was observed in this parent sample. For the Mn-doped samples, however, positive magnetization were observed between 5 and 300 K even if the x value is as low as 0.03. The mass susceptibility enhances with Mn content and it reaches the highest value of 1.4×10 -3 emu/g Oe (at T=300 K) at x=0.45. Furthermore, the Mn-doped oxides with x=0.06 and 0.2, respectively, exhibit nonlinear magnetization curves and small hysteretic loops in low magnetic fields. Susceptibilities of the Mn-doped samples are much higher than those of MnO 2 , Mn 2 O 3 oxides, and Mn metals. These results show that the oxides have potential to be magnetic semiconductors. © 2006 Elsevier B.V. All rights reserved.