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Kinetic studies on the hydrothermal crystallization of Co-doped nanostructured TiO2 anatase with ferromagnetic properties

R. R PITICESCU1, S. N. VALSAN1, M. PETRICEANU1, V. BADILITA1, I. A. TUDOR1,* , D. TALOI1, B. VASILE2, O. RAITA3

Affiliation

  1. National R&D Institute for Non-Ferrous and Rare Metals, 102 Biruintei blvd., Pantelimon, Ilfov, 077145 Romania
  2. University Politehnica Bucharest, Faculty of Applied Chemistry and Materials Science, 313 Splaiul Independentei, Bucharest, Romania
  3. National R&D Institute of Isotopes and Molecular Technologies, 65-103 Donath Str., 400293 Cluj-Napoca 5, România

Abstract

Nanopowders based on Co-doped TiO2 anatase (with Co content in the range 0-5 at %) with rod-like structure and homogeneous distribution of the doping agent were obtained by hydrothermal synthesis in the temperature range 200-2750C in the presence of KOH as mineralizing agent. The kinetic triplet of crystallization (activation energy, reaction orders and pre-exponential factors) were calculated from DSC measurements using Avrami-Erofeev equation. For pure TiO2 the best fitting reaction order was found n=1 while for 2.5 and 5 at% Co-doped TiO2 the reaction order is n=2/3. The evolution the activation energy with increasing Co content may be attributed to the increasing of defects in the crystalline lattice, as suggested by EPR results. The EPR investigations show also different ferromagnetic behaviours with increasing Co concentration..

Keywords

Hydrothermal synthesis, activation energy, Co-doped anatase, nanosize particles, EPR.

Submitted at: Nov. 6, 2014
Accepted at: May 7, 2015

Citation

R. R PITICESCU, S. N. VALSAN, M. PETRICEANU, V. BADILITA, I. A. TUDOR, D. TALOI, B. VASILE, O. RAITA, Kinetic studies on the hydrothermal crystallization of Co-doped nanostructured TiO2 anatase with ferromagnetic properties, Journal of Optoelectronics and Advanced Materials Vol. 17, Iss. 5-6, pp. 646-654 (2015)