.: 2012 Scientific Report

1. Monophase BaTiO₃ powders has been prepared by hydrothermal method

XRD patterns of the hydrothermal powders showing that phase pure BaTiO₃ is obtained independently of the reaction temperature and mineralizer concentration a) 135 °C and 10 M mineralizer concentration; b) 200 °C and 10 M mineralizer concentration; c) 200 °C and 20 M mineralizer concentration

2. The synthesis process to obtained one-dimension (1D) BaTiO₃ nanostructures it is optimized; Structural and microstructural characterization mainly by electron microscopy techniques; Synthesis parameters studied: reaction temperature and mineralizer concentration

Bright field (left) and dark field (right) TEM images of BaTiO3 1D nanorods obtained at 200 °C and 10 M mineralizer concentration; In the dark field image the ferroelectric domains along the rod axis are illustrated.

.: 2013 Scientific Report

1. The synthesis process to obtained BaTiO₃ nanostructures it is optimized; Structural and microstructural characterization mainly by electron microscopy techniques; Synthesis parameters studied: barium and titanium precursors

SEM images of the BaTiO3 hydrothermal powders showing the formation of hollow particles when using titanium based nanotubes as titanium precursors and barium chloride as barium source. The relations between processing, structure and morphology development of the BaTiO3 nanostructures has been established; The growth mechanism of the hollow BaTiO3 particles was attributed to the Kirkendall effect (http://dx.doi.org/10.1002/ejic.201402497).

2. Synthesis of monophase BiFeO₃ powders by hydrothermal method

XRD patterns of the hydrothermal powders showing that perovskite phase BiFeO₃ is obtained for 12 M mineralizer concentration

3. Electrical and thermodynamic characterization of the obtained nanostructures

(Left side) Electric properties: Dielectric constant  and dielectric losses as a function of temperature for the BaTiO3 ceramics obtained from the hydrothermal powders; (Right side) Thermodynamic properties: The relative partial molar free energies of the oxygen dissolution in the perovskite BaTiO3 phase.

.: 2014 Scientific Report

1. The synthesis process to obtained predominantly 1D BaTiO₃ has been optimized; Structural and microstructural characterization of the 1D nanostructures

SEM (left) and TEM (right) micrographs showing the formation of BaTiO3 powders with predominant 1D morphology – average aspect ratio aprox. 3

2. The relations between processing, structure / microstructure and properties has been established and the properties - dimensionality dependence has been determined

The dielectric constant as a function of temperature (left) and the schematic representation of the dielectric constant and the Curie temperature dependence on the BaTiO3 morphology (right). It is shown the increasing of the dielectric constant and the decreasing of the Curie temperature for the 1D BaTiO3 ceramics.

The correlation between the energetic parameters and the BaTiO₃ powder morphologies obtained by thermodynamic characterization. Higher thermodynamic stability is obtained for 1D BaTiO₃ when comparing to other morphologies

1D nanoPEROVSKITES © Copyright Institute of Physical Chemistry Ilie Murgulescu 2013, All rights reserved.

Contacts