Crystal growth and characterization of (DyxLa1–x)2Ti2O7 crystals

LaTiO3.5 crystals were grown by optical floating zone technique in air, O2, or Ar.Crystal structure varies between orthorhombic Pna21 (air, O2) and monoclinic P21 (Ar).Crystals are transparent (air, O2) or opaque (Ar) with amber or black colour.Magnetisation resembles the properties of LaTiO3.5.(DyxLa1-x)2Ti2O7 crystals were grown in O2.The solubility of dopant (La or Dy) in the parent compound is limited.Two phases with Pna21 and F d 3m structure coexist in the range from x = 0.32 to 0.68.The a-axis of Pna21 is intact by substitution of La 3+ by Dy 3+ ; both b-and c-axes decrease.The a-axis of F d 3m increases with substitution of Dy 3+ by La 3+ and the spin freezing temperature T f shifts to a higher temperature.Either of the new magnetic phase (Pna21 structure) or dynamical behaviour of spins in F d 3m phase exists below x = 0.68 in the range between the transition to 'spin ice' state Ti and T f .K e y w