Complex GdSc_1–<i>x</i>In_<i>x</i>O₃ Oxides: Synthesis and Structure Driven Tunable Electrical Properties

Abstract

Detailed structural and electrical investigations were carried out on a GdSc1–xInxO3 (0.0 ≤ x ≤ 1.0) series. The solubility of In3+ in GdScO3 could be increased by 20 mol % by changing the synthesis route. GdScO3, a technologically important dielectric material, could be synthesized at a temperature as low as 850 °C. An orthorhombic modification of GdInO3 could be stabilized by 20 mol % Sc3+ substitution, which is otherwise known to prefer hexagonal polymorphs. Nonpreference of trigonal bipyramidal coordination by Sc3+ led to the existence of a very narrow biphasic field. A very interesting observation is the existence of same nominal composition (GdSc0.1In0.9O3) in two different modifications (orthorhombic and hexagonal) in the biphasic region. Careful Raman spectroscopic studies highlighted the fact that the local polyhedral coordination of the Sc3+/In3+ undergoes an abrupt change as the phase relations evolve from orthorhombic to hexagonal phase field. The trend in the net shrinkage observed on the powder compacts matched well with the theoretical X-ray density calculated for various nominal compositions. A careful control of the composition, and consequently, the optimization of the structure, led to tuning of electrical behavior for the system GdSc1–xInxO3 from a conventional dielectric (up to x = 0.8) to a classical relaxor ferroelectric, for the nominal composition GdSc0.9In0.1O3.