Growth and Investigation of Nd_{1-x}Sm_{x}ScO_{3} and Sm_{1-x}Gd_{x}ScO_{3} Solid-Solution Single Crystals

TL;DR

This study reports the growth and characterization of Nd_{1-x}Sm_{x}ScO_{3} and Sm_{1-x}Gd_{x}ScO_{3} solid-solution single crystals, which serve as suitable substrates with specific lattice parameters for thin film applications.

Contribution

It introduces new solid-solution single crystals as substitutes for problematic rare-earth scandates in the perovskite substrate range.

Findings

Solid solutions have lattice parameters close to target compounds.

They exhibit very low segregation during growth.

Suitable for use as perovskite substrates in thin film growth.

Abstract

The pseudo-cubic lattice parameters of rare-earth (RE) scandate, REScO3, single crystals grown by the Czochralski technique with RE=Dy to Pr lie between about 3.95 and 4.02 Angstrom. These crystals are the only available perovskite substrates in this lattice constant range that can withstand virtually any thin film growth conditions. Two members of this series, PmScO3 and EuScO3, are, however, not suitable for substrate applications. Because the pseudo-cubic lattice parameters between neighbouring REScO3 compounds decrease with rising atomic number of the RE in about 0.01 Angstrom steps, the unsuitability of PmScO3 (radioactivity) and EuScO3 (incompatibility with Si) causes an interruption in this lattice spacing sequence. To replace them, solid solutions of their adjacent rare-earth scandates, i.e., (Nd0.5Sm0.5)ScO3 and (Sm0.5Gd0.5)ScO3, were grown by the Czochralski method. Their average pseudo-cubic lattice parameters of 3.9979 Angstrom and 3.9784 Angstrom are very close to those of PmScO3 and EuScO3, respectively, and they show very low segregation. These qualities make these solid solutions excellent substitutes for PmScO3 and EuScO3.