Geneva Laurita

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The structure of the hybrid perovskite HC(NH2 )2 PbI3 (formamidinium lead iodide) reflects competing interactions associated with molecular motion, hydrogen bonding tendencies, thermally activated soft octahedral rotations, and the propensity for the Pb(2+) lone pair to express its stereochemistry. High-resolution synchrotron X-ray powder diffraction(More)
SiAlON ceramics, solid solutions based on the Si3N4 structure, are important, lightweight structural materials with intrinsically high strength, high hardness, and high thermal and chemical stability. Described by the chemical formula β-Si6-zAlzOzN8-z, from a compositional viewpoint, these materials can be regarded as solid solutions between Si3N4 and(More)
Heusler compounds XY 2 Z with 24 valence electrons per formula unit are potential thermoelectric materials, given their thermal and chemical stability and their relatively earth-abundant constituent elements. We present results on the 24-electron compound TiFe2Sn here. First principles calculations on this compound suggest semiconducting behavior. A(More)
Stable s(2) lone pair electrons on heavy main-group elements in their lower oxidation states drive a range of important phenomena, such as the emergence of polar ground states in some ferroic materials. Here we study the perovskite halide CsSnBr3 as an embodiment of the broader materials class. We show that lone pair stereochemical activity due to the(More)
The cubic semiconducting compounds APd3O4 (A = Ca, Sr) can be hole-doped by Na substitution on the A site and driven toward more conducting states. This process has been followed here by a number of experimental techniques to understand the evolution of electronic properties. While an insulator-to-metal transition is observed in Ca1-xNaxPd3O4 for x ≥ 0.15,(More)
Hybrid halide perovskites combine ease of preparation and relatively abundant constituent elements with fascinating photophysical properties. Descriptions of the chemical and structural drivers of the remarkable properties have often focused on the potential role of the dynamic order/disorder of the molecular A-site cations. We reveal here a key aspect of(More)
Polycrystalline samples of the pyrochlore series Ag(1-x)M(n)(x)SbO(3+x[(n-1)/2]) (M = Na, K, and Tl) have been structurally analyzed through total scattering techniques. The upper limits of x obtained were 0.05 for Na, 0.16 for K, and 0.17 for Tl. The Ag(+) cation occupies a site with inversion symmetry on a 3-fold axis. When the smaller Na(+) cation(More)
Materials Research Laboratory University of California, Santa Barbara, California 93106, USA, Materials Department University of California, Santa Barbara, California 93106, USA, Department of Chemistry, and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208, USA, and Department of Chemistry and(More)
Structural disorder can play an important role in the electrical properties of correlated materials. In this work we examine the average and local disorder in hollandites A(x)Ru4O8 (A(+) = K, Rb, Rb(1-x)Na(x)) through neutron total scattering techniques. Samples with A(+) = Rb, Rb(1-x)Na(x) exhibit the largest amount of local disorder as evidenced by higher(More)
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