title: Structural Effects of Lanthanide Dopants on Alumina.
abstract: Lanthanide (Ln3+) doping in alumina has shown great promise for stabilizing and promoting desirable phase formation to achieve optimized physical and chemical properties. However, doping alumina with Ln elements is generally accompanied by formation of new phases (i.e. LnAlO3, Ln2O3), and therefore inclusion of Ln-doping mechanisms for phase stabilization of the alumina lattice is indispensable. In this study, Ln-doping (400 ppm) of the alumina lattice crucially delays the onset of phase transformation and enables phase population control, which is achieved without the formation of new phases. The delay in phase transition (θ → α), and alteration of powder morphology, particle dimensions, and composition ratios between α- and θ-alumina phases are studied using a combination of solid state nuclear magnetic resonance, electron microscopy, digital scanning calorimetry, and high resolution X-ray diffraction with refinement fitting. Loading alumina with a sparse concentration of Ln-dopants suggests that the dopants reside in the vacant octahedral locations within the alumina lattice, where complete conversion into the thermodynamically stable α-domain is shown in dysprosium (Dy)- and lutetium (Lu)-doped alumina. This study opens up the potential to control the structure and phase composition of Ln-doped alumina for emerging applications.
authors.affiliation: Department of Mechanical Engineering and Temple Materials Institute, Temple University, Philadelphia, PA 19122, USA.
authors.forename: Ketan
authors.initials: K
authors.lastname: Patel
authors.affiliation: US Army Research Laboratory, Aberdeen Proving Ground, MD 21005, USA.
authors.forename: Victoria
authors.initials: V
authors.lastname: Blair
authors.affiliation: Molecular Structures Group, University of Kansas, Lawrence, KS 66045, USA.
authors.forename: Justin
authors.initials: J
authors.lastname: Douglas
authors.affiliation: Department of Mechanical Engineering and Temple Materials Institute, Temple University, Philadelphia, PA 19122, USA.
authors.forename: Qilin
authors.initials: Q
authors.lastname: Dai
authors.affiliation: Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
authors.forename: Yaohua
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Mechanical Engineering and Temple Materials Institute, Temple University, Philadelphia, PA 19122, USA.
authors.forename: Shenqiang
authors.initials: S
authors.lastname: Ren
authors.affiliation: US Army Research Laboratory, Aberdeen Proving Ground, MD 21005, USA.
authors.forename: Raymond
authors.initials: R
authors.lastname: Brennan