Structural confinement effects of amorphous ternary chalcogenide of Ni-3(SbTe3)(2) in mesoporous channels of different pore diameters have been studied. Insertion of the guest into the channels of AlMCM-41 was probed by the results of transmission electron microscopy (TEM), nitrogen adsorption, X-ray diffraction (XRD), and photoluminescence (PL) and photoluminescence excitation (PLE). From powder XRD patterns, characteristic diffraction peaks were observed for the ternary chalcogenide incorporated in AlMCM-41, which indicated long-range ordering and increased crystallinity. The competition between the homogeneous broadening and the inhomogeneous broadening of the characteristic XRD peak profiles of the guest chalcogenides are evaluated in a series of the hosts. As the mesopore diameter decreases. the strain is enlarged in the nanosize guest chalcogenide while the estimated particle size from the full width at half-maximum (fwhm) of the respective Lorentzian profiles is similarly preserved. The characteristic energy level, for the nanophase ternary chalcogenide, induced by the strain is gradually red shifted in the nanocomposites with decreasing the pore diameter. The structural confinement causes the suppression of phonon coupling to the photoexcited carriers in the ternary chalcogenide incorporated in AlMCM-41, and the coupling is more suppressed in the nanocomposite of smaller pore diameter. Such phonon suppression induced by the structural confinement results in longer PL lifetimes as the pore diameter decreases.