Cooperative Phenomena in Dielectrics (FCD)

- Group members

Effective Members: -José Luís Ribeiro – Associate Professor with Habilitation -Etelvina de Matos Gomes - Associate Professor -Senen Lanceros-Mendéz - Associate Professor -Bernardo Gonçalves Almeida - Assistant Professor -Luís Manuel Gomes Vieira - Assistant Professor Associate Member: -Jorge António Silva Mendes, Assistant Professor, Instituto Politécnico do Porto Post-Doctorate Researchers and Research Fellows with PhD: -Dmitry V. Isakov– Research Fellow with PhD -Vitor Sencadas – FCT Post-Doc grant -Pedro Libanio Martins - FCT Post-Doc grant -Vanessa Cardoso - FCT Post-Doc grant -Vitor Correia - FCT Post-Doc grant -Clarisse Ribeiro - FCT Post-Doc grant -Catarina Lopes- FCT Post-Doc grant -João Pereira - FCT Post-Doc Grant -Pedro Costa - FCT Post-Doc grant -Marcos Silva Martins - - FCT Post-Doc grant PhD and other Research Students: -Atilla Goren, Ph-D student, FCT grant -Sofia Fernandez, Ph-D student, FCT grant -Susana Catarino, Ph-D student, FCT grant -Gabriel Mendes, Ph-D student, FCT grant -Juan Alberto Panadero, Ph-D student, FCT grant -Paulo Sousa, Ph-D student, FCT grant -Silvia Reis, Ph-D student, FCT grant -Armando Ferreira, Ph-D student, FCT grant -Carlos Costa, Ph-D student, FCT grant -Daniel Miranda, Ph-D student, FCT grant -Helder Castro, Ph-D student, FCT grant -Daniela Correia, Ph-D student, FCT grant -Vania Pinto, Ph-D student, FCT grant -Joana Oliveira, Ph-D student, FCT grant -Ricardo Sousa - Ph-D student, FCT grant -Juliana Dias, Ph-D student, FCT grant -Juliana Oliveira, Ph-D student, FCT grant -Marco Silva, Ph-D student, FCT grant -Renato Gonçalves, Ph-D student, FCT grant

- Research

The research performed in the group is directed to the synthesis, characterization and modelling of the properties of new dielectric materials presenting polar and/or magnetic cooperative phases. The group has developed experimental infrastructures having laboratories for the synthesis and crystal growth, dielectric characterization in the radio-frequency and microwave regions, laser ablation deposition of thin films and infrared spectroscopy. Currently it is developing systems for magnetic and electro-mechanical characterization. The group has paid particular attention to the production and characterization of crystals with high electrical polarizability, non-homogeneous thin films with polar and magnetic interactions, to the study of cooperative phenomena on H-bonded crystals and to the study of piezoelectric polymers.

Dielectric Properties Laboratory
  

Infrared Spectroscopy Laboratory
 

Crystal Growth Laboratory
 

Laser Ablation Laboratory
 

- Materials/research areas
 

AFM micrograph and corresponding grain size distribution histogram, obtained on a BaTiO₃-CoFe₂O₄ nanogranular composite, with 20% cobalt ferrite concentration. (Bernardo Almeida, 2006)

                                         

Room temperature infrared reflectivity spectra of the semi-organic crystal CsLM (CsH(C₄H₄O₅).H₂O) (circles) for incident light polarized along the <!--[if !vml]--><!--[endif]-->axis (a) and in the ac plane (b-d). The spectra b-d correspond to incident light polarized along directions forming angles of <!--[if !vml]--><!--[endif]--> (b), <!--[if !vml]--><!--[endif]--> (c) and <!--[if !vml]--><!--[endif]--> (d) relative to the crystallographic c-axis. The red lines are fits of the data. (José Luís Ribeiro, 2006)

                         

Axial dispersion in the semi-organic crystal CsLM (CsH(C₄H₄O₅).H₂O) deduced from reflectivity data: orientation of the optical axes and principal dielectric axes of the permittivity in the ac-plane for the frequencies of  9398 cm^-1 (a) and 1cm^-1 (b). (José Luís Ribeiro, 2006)

                                 

SEM image of an α -PVDF sample cooled at room temperature, showing a spherule with ~40µm diameter. (Senentxu Lanceros Mendez, 2006)

SEM image of a 3D network in an electroactive poliymer, with 80 µm average size. (Senentxu Lanceros Mendez, 2006)

Non-centrosymmetric organic and semi-organic crystals of:  ceasium hydrogen L-malate monohydrate - CsLM (upper left), urea L-malic acid – ULMA  (upper right) and  para-nitroaniline-  pNA (lower right). (Dmitriy Isakov, Etelvina Gomes, 2007)

- Selected papers

Papers inserted in RepositoriUM

- Group site.

http://www.fisica.uminho.pt/FCD