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Title: Self-standing elastomeric composites based on lithium ferrites and their dielectric behavior

Lithium ferrite (LiFe{sub 5}O{sub 8}) is an attractive material for technological applications due to its physical properties, which are significantly dependent on the preparation method and raw materials. In this work, LiFe{sub 5}O{sub 8} crystallites were obtained by controlled heat-treatment process at 1100 °C, of a homogeneous mixture of Li{sub 2}O-Fe{sub 2}O{sub 3} powders, prepared by wet ball-milling and using lithium and iron nitrates as raw materials. The main goal was the preparation of a flexible and self-standing tick composite film by embedding lithium ferrite particles in a polymeric matrix, taking advantage of the good mechanical properties of the polymer and of the electrical and dielectric properties of the ferrite. The selected polymer matrix was styrene-b-isoprene-b-styrene copolymer. To prepare the composites, the lithium ferrite particles were chemically modified in order to functionalize their surface. To analyse the influence of the particles surface modification, different composites were made, with modified and unmodified particles. The structure of the obtained composites was studied by FTIR, XRD, TGA, and DSC techniques. The dielectric properties were analysed, in the frequency range between 10 Hz and 1 MHz and in function of temperature in the range between −73 °C and 127 °C. These properties were related with the structure and concentrationmore » of the particles in the matrix network. The composites with the modified particles present higher dielectric constant, maintaining values of loss tangent sufficiently low (<10{sup −2}) that can be considered interesting for technological applications.« less
Authors:
; ;  [1] ;  [2] ; ; ;  [3] ;  [3] ;  [4]
  1. I3N and Physics Department, University of Aveiro, 3810-193 Aveiro (Portugal)
  2. REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)
  3. Polymer Institute, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava (Slovakia)
  4. (Qatar)
Publication Date:
OSTI Identifier:
22402777
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 22; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; COPOLYMERS; DIELECTRIC MATERIALS; FERRITES; INFRARED SPECTRA; IRON NITRATES; IRON OXIDES; ISOPRENE; LITHIUM; LITHIUM OXIDES; MECHANICAL PROPERTIES; MHZ RANGE 01-100; MILLING; PARTICLES; PERMITTIVITY; RAW MATERIALS; STYRENE; TEMPERATURE DEPENDENCE; THERMAL GRAVIMETRIC ANALYSIS; X-RAY DIFFRACTION