Zn~ 2+ -or Ti~ 4+ -substituted cordierites with the nominal compositions of Mg_ 1.6 Zn_ 0.4 Al_4Si_5O_ 18 and Mg_ 1.8 Ti_ 0.2 Al_ 4.4 Si_ 4.6 O_ 18 respectively, were prepared by a conventional solid state reaction method. The structure of the substituted cordierites was characterized by X-ray diffraction (XRD), infrared (IR) spectroscopy and ~ 29 Si magic angle spinning (MAS) nuclear magnetic resonance (NMR). The infrared radiation properties were investigated in the bands within 2.5-25 μm. Compared with the un-substituted cordierite composition (Mg_2Al_4Si_5O_ 18 ), Zn~ 2+ -or Ti~ 4+ -substituted cordierites show superior infrared properties. XRD and IR results confirm the formation of hexagonal α-cordierite as the main crystal phase for the substituted cordierites. ~ 29 Si MAS NMR result indicates that Zn~ 2+ or Ti~ 4+ substitutions for partial Mg~ 2+ of α-cordierite promoted the ordering of the distribution of Al and Si atoms in T_1 (tetrahedra connecting six-membered rings together with [MgO_6] octahedra) and T_2 (tetraheda forming six-membered rings) tetrahedral sites. This resulted in a lattice deformation and increased the anharmonicity of polarization vibration, which is responsible for the improvement of infrared radiation properties of the substituted cordierites. Zn ~ 2+ -or Ti ~ 4+ -substituted cordierites with the nominal compositions of Mg_ 1.6 Zn_ 0.4 Al_4Si_5O_ 18 and Mg_ 1.8 Ti_ 0.2 Al_ 4.4 Si_ 4.6 O_ 18 respectively, prepared by a conventional solid state reaction method. The structure of the substituted cordierites were characterized by X-ray diffraction (XRD), infrared (IR) spectroscopy and ~ 29 Si magic angle spinning (MAS) nuclear magnetic resonance Compared with the un-substituted cordierite composition (Mg_2Al_4Si_5O_ 18), Zn ~ 2+ -or Ti ~ 4 + -substituted cordierites show superior infrared properties. XRD and IR results confirm the formation of hexagonal α-cordierite as the main crystal phase for the substituted cordierites ~ 29 Si MAS NMR results indicate that Zn ~ 2+ or Ti ~ 4+ substitutions for partial Mg ~ 2+ of α-cordierite promoted the ordering of the distribution of Al and Si atoms in T_1 (tetrahedra connecting six- membered rings toge ther with [MgO_6] octahedra) and T_2 (tetraheda forming six-membered rings) tetrahedral sites. This resulted in a lattice deformation and increased the anharmonicity of polarization vibration, which is responsible for the improvement of infrared radiation properties of the substituted cordierites.