Dielectric, magnetic and structural properties of novel multiferroic Eu_0.5Ba_0.5TiO₃ ceramics

Author： Goian V Kamba S Nuzhnyy D Vaněk P Kempa M Bovtun V Knížek K Prokleška J Borodavka F Ledinský M Gregora I

ISSN： 0953-8984

Source： Journal of Physics: Condensed Matter, Vol.23, Iss.2, 2011-01, pp. : 25904-25910

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Abstract

Dielectric properties of Eu_0.5Ba_0.5TiO₃ ceramics were investigated between 10 and 300 K in the frequency range of 1 MHz–100 THz. Permittivity exhibits a strong peak near the ferroelectric phase transition at 215 K. This is mainly due to softening of the lowest frequency polar phonon revealed in THz and infrared spectra. Dielectric relaxation was observed also below the ferroelectric soft mode frequency in the whole investigated temperature region, but it is probably caused by some defects such as Eu^{3 +} cations or oxygen vacancies. This implies that the ferroelectric phase transition has predominantly a displacive character. Raman scattering spectra revealed a lowering of crystal symmetry in the ferroelectric phase and XRD analysis indicated orthorhombic A2mm symmetry below 215 K. The magnetic measurements performed at various frequencies in the field cooled and field heating regime after cooling in zero magnetic fields excluded spin glass behavior and proved an antiferromagnetic order below 1.9 K in Eu_0.5Ba_0.5TiO₃.