Properties of rare-earth scandate single crystals (Re=Nd−Dy)

Rare-earth (RE) scandate single crystals ranging from NdScO3 to DyScO3 were grown by the conventional Czochralski technique. The crystals were found to have a non-stoichiometric composition caused by RE-deficiency on the A-site of the distorted perovskite structure. Their pseudocubic lattice constants lie between 3.95 and 4.01 Å and their average thermal expansion coefficients are between 8.2×10−6 and 10.9×10−6 K−1. The pseudocubic lattice constants of the RE scandates vary in about 0.01 Å steps as the RE series is traversed, enabling the growth of substrates appropriate for the strain engineering of perovskite thin films. The crystalline perfection and homogeneity of the DyScO3 and GdScO3 single crystals are characterized by a full-width at half-maximum of the 220 reflection of the substrates of about 20–25 arcsec in ω and a very small fluctuation margin of about ±3 arcsec over the whole wafer surface. The average dislocation density of the RE scandate crystals was 103–105 cm−2. These characteristics make RE scandate single crystals some of the best available substrates for the epitaxial growth of perovskite thin films.