Zn2+ - or Ti4+ -substituted cordierites with the nominal compositions of Mg1.6 Zn0.4 Al4 Si5 O18 and Mg1.8 Ti0.2 Al4.4 Si4.6 O18 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 ( Mg2 Al4 Si5 O18 ), Zn2+ - or Ti4+ -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 Zn2+ or Ti4+ substitutions for partial Mg2+ of a- cordierite promoted the ordering of the distribution of Al and Si atoms in T1 ( tetrahedra connecting six-membered rings together with [ MgO6 ] octahedra ) and T2 ( 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.