In this paper, the dilution effects of non-magnetic Y ions on spin-ice compound Dy2Ti2O7 by infrared and Raman spectra and magnetization measurements were investigated. An anomalous phonon softening with temperature decreasing is found in both the parent and diluted compounds, and Y doping can relax the softening of phonons except that of the IR mode near 233 cm-1, indicating a strong phonon–phonon coupling in the spin-ice material.The magnetization measurements reveal that the nonmagnetic impurities do not severely influence the spin-ice rules in the ground state when the level of dilution is not very high. However, a large amount of dilution enhance the disorder and break the spin-ice state because the collective spin-flip clusters are no longer available.
