Journal of Materials Research

Articles

Synthesis of nanometer-sized particles of barium orthotitanate prepared through a modified reverse micellar route: Structural characterization, phase stability and dielectric properties

Tokeer Ahmada1 and Ashok K. Gangulia1 c1

a1 Department of Chemistry, Indian Institute of Technology, Hauz Khas, New Delhi 110016, India

Abstract

Nanoparticles of barium orthotitanate (Ba2TiO4) was obtained using microemulsions (avoiding Ba-alkoxide). Powder x-ray diffraction studies of the powder after calcining at 800 °C resulted in a mixture of orthorhombic (70%) and monoclinic (30%) phases. The high-temperature orthorhombic form present at 800 °C was due to the small size of particles obtained by the reverse micellar route. Pure orthorhombic Ba2TiO4 was obtained on further sintering at 1000 °C with lattice parameters a = 6.101(2) Å, b =22.94(1) Å, c = 10.533(2) Å (space group, P21nb). The particle size obtained from x-ray line broadening studies and transmission electron microscopic studies was found to be 40–50 nm for the powder obtained after heating at 800 °C. Sintering at 1000 °C showed increase in grain size up to 150 nm. Our studies corroborate well with the presence of a martensitic transition in Ba2TiO4. The dielectric constant was found to be 40 for Ba2TiO4 (at 100 kHz) for samples sintered at 1000 °C. The dielectric loss obtained was low (0.06) at 100 kHz.

(Received December 14 2003)

(Accepted June 02 2004)

(Online publication October 2004)

Key Words:

  • Chemical synthesis;
  • Dielectric properties;
  • Nanoparticle

Correspondence:

c1 Address all correspondence to this author. e-mail: ashok@chemistry.iitd.ernet.in

0Comments