title: Average and local structure, debye temperature, and structural rigidity in some oxide compounds related to phosphor hosts.
abstract: The average and local structure of the oxides Ba2SiO4, BaAl2O4, SrAl2O4, and Y2SiO5 are examined to evaluate crystal rigidity in light of recent studies suggesting that highly connected and rigid structures yield the best phosphor hosts. Simultaneous momentum-space refinements of synchrotron X-ray and neutron scattering yield accurate average crystal structures, with reliable atomic displacement parameters. The Debye temperature ΘD, which has proven to be a useful proxy for structural rigidity, is extracted from the experimental atomic displacement parameters and compared with predictions from density functional theory calculations and experimental low-temperature heat capacity measurements. The role of static disorder on the measured displacement parameters, and the resulting Debye temperatures, are also analyzed using pair distribution function of total neutron scattering, as refined over varying distance ranges of the pair distribution function. The interplay between optimal bonding in the structure, structural rigidity, and correlated motion in these structures is examined, and the different contributions are delineated.
authors: †Materials Research Laboratory, University of California, Santa Barbara, California 93106, United States.|‡Materials Department, University of California, Santa Barbara, California 93106, United States.
authors: Kristin A
authors: KA
authors: Denault
authors: ¶Department of Chemistry, University of Houston, Houston, Texas 77024, United States.
authors: Jakoah
authors: J
authors: Brgoch
authors: †Materials Research Laboratory, University of California, Santa Barbara, California 93106, United States.|§Department Chemie, Ludwig-Maximilians-Universität, Munich 81377, Germany.
authors: Simon D
authors: SD
authors: Kloss
authors: †Materials Research Laboratory, University of California, Santa Barbara, California 93106, United States.|∥Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States.
authors: Michael W
authors: MW
authors: Gaultois
authors: ⊥Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.
authors: Joan
authors: J
authors: Siewenie
authors: ⊥Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.|#Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6475, United States.
authors: Katharine
authors: K
authors: Page
authors: †Materials Research Laboratory, University of California, Santa Barbara, California 93106, United States.|‡Materials Department, University of California, Santa Barbara, California 93106, United States.|∥Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, United States.
authors: Ram
authors: R
authors: Seshadri
keywords: Debye temperature; correlated atomic motion; heat capacity; pair distribution function; phosphors; structural rigidity