Laser-induced crystallization of β′-RE2(MoO4)3 ferroelectrics (RE: Sm, Gd, Dy) in glasses and their surface morphologies

The glasses with the compositions of 21.25RE2O3–63.75MoO3–15B2O3 (RE: Sm, Gd, Dy) were prepared and the formation of β′-RE2(MoO4)3 ferroelectrics was confirmed in the crystallized glasses obtained through a conventional crystallization in an electric furnace. The features of the glass structure and crystallization behavior were clarified from measurements of Raman scattering spectra. Continuous-wave Nd:YAG laser with a wavelength of 1064 nm (laser power: 0.6–0.9 W, laser scanning speed: S = 1–16 μm/s) was irradiated to 10.625Sm2O3–10.625Gd2O3 (or Dy2O3)–63.75MoO3–15B2O3 glasses, and the structural modification was induced at the glass surface. At the scanning speed of S = 10 μm/s, crystal lines consisting of β′-Gd2−xSmx(MoO4)3 or β′-Dy2−xSmx(MoO4)3 crystals were patterned on the glass surface. It was found that those crystal lines have the surface morphology with periodic bumps. At S = 1 μm/s, it was found that crystal lines consist of the mixture of paraelectric α-Gd2−xSmx(MoO4)3 and ferroelectric β′-Gd2−xSmx(MoO4)3 crystals, indicating the phase transformation from the β′ phase to the α phase during laser irradiation. Homogeneous crystal lines with β′-RE2(MoO4)3 ferroelectrics have not been written in this study, but further research is continuing.