Identification des loci génétiques associés à la stéatose hépatique chez la souche murine C58/J sous diète hyperlipidique

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal

Correction: A feasible pathway to stabilize monoclinic and tetragonal phase coexistence in barium titanate-based ceramics

Depto. de Física de MaterialesFac. de Ciencias FísicasTRUEpu

A feasible pathway to stabilize monoclinic and tetragonal phase coexistence in barium titanate-based ceramics

Multiphase coexistence has attracted significant interest in recent years because its control has entailed a significant breakthrough for the piezoelectric activity enhancement of lead-free piezoelectric oxides. However, the comprehension of phase coexistence still has many controversies including an adequate synthesis process and/or the role played by crystalline phases in functional properties. In this study, functional barium titanate [BaTiO_(3), (BTO)]-based materials with tunable functional properties were obtained by compositional modification via Bismuth (Bi) doping. Towards this aim, we systematically synthesized BTO-based materials by a sol-gel method, focusing on the control of Bi substitution in the BaTiO_(3) structure. In particular, we found that the substitution of Bi^(+3) leads to the stabilization of a monoclinic-tetragonal (M-T) phase boundary close to room temperature, which facilities the polarization process of the system. As a surprising result, we believe that the simple and cost-effective strategy and design principles described in this work open up the possibility of obtaining BTO-based lead-free ceramics with enhanced properties induced by the stabilization of the phase coexistence, expanding their application range

Implementing a sol-gel route to adjust the structural and dielectric characteristics of Bi and Fe co-doped BaTiO3 ceramics

The present work explores the impact of Fe insertion on the physical properties of Ba0.95Bi0.05Ti1-xFexO3 (x = 0.025, 0.050, and 0.075) prepared via sol gel method. The resulting samples crystallize in the tetragonal structure with space group P4mm and their morphological features point out the variation of the microstructure with Fe content. In turn, the dielectric constant versus temperature plot reveals the existence of two transition phases: the first one is ferroelectric-paraelectric transition phase (TF-P) and the second one is ferroelectric orthorhombic - ferroelectric tetragonal phase (TO-T). Analysis of conductivity curves using Jonscher’s augmented equation (for x = 0.025) and Jonscher’s power law (for x = 0.075) suggests the Non-Overlapping Small Polaron Tunneling (NSPT) model as a conduction mechanism.publishe