Doping gamma-Fe(2)O(3) nanoparticles with Mn(III) suppresses the transition to the alpha-Fe(2)O(3) structure

Jriuan Lai; Kurikka V P M Shafi; Katja Loos; Abraham Ulman; Yongjae Lee; Thomas Vogt; Claude Estournès

doi:10.1021/ja035409d

Doping gamma-Fe(2)O(3) nanoparticles with Mn(III) suppresses the transition to the alpha-Fe(2)O(3) structure

J Am Chem Soc. 2003 Sep 24;125(38):11470-1. doi: 10.1021/ja035409d.

Authors

Jriuan Lai¹, Kurikka V P M Shafi, Katja Loos, Abraham Ulman, Yongjae Lee, Thomas Vogt, Claude Estournès

Affiliation

¹ Department of Chemical Engineering, Chemistry & Material Science, Polytechnic University, 6 Metrotech Center Brooklyn, New York 11201, USA.

PMID: 13129329
DOI: 10.1021/ja035409d

Abstract

Here we report on a mixed oxide system, gamma-Fe2O3 nanoparticles doped with Mn(III), where the transition from the cubic to the more stable hexagonal alpha-Fe2O3 structure is suppressed. When amorphous Fe2O3 is heated at 300 degrees C for 3 h, ferrimagnetic gamma-Fe2O3 is observed as the sole product. On the other hand, when the temperature is raised to 500 degrees C, one observes only antiferromagnetic alpha-Fe2O3 as the product. However, upon doping with 8.5 wt % Mn(III), the amorphous nanoparticles crystallized to mainly the gamma-Fe2O3 matrix after heating at 500 degrees C for 3 h, and need to be heated to >650 degrees C for the complete transition to the alpha-Fe2O3 structure to take place.