A novel near-room-temperature type I multiferroic: Pb(Fe0.5Ti0.25W0.25)O3 with coexistence of ferroelectricity and weak ferromagnetism

SEBASTIAÌN A. LARREÌGOLA; JOSEÌ C. PEDREGOSA; MIGUEL ALGUEROÌ; RICARDO JIMEÌNEZ; MAR GARCÍA-HERNANDEZ; MARÍA T. FERNAÌNDEZ-DÍAZ; JOSEÌ A. ALONSO

CHEMISTRY OF MATERIALS

AMER CHEMICAL SOC

Lugar: Washington; Año: 2012 vol. 24 p. 2664 - 2672

0897-4756

ABSTRACT: We report on the crystal structure evolution and the physical properties of the complex perovskite Pb(Fe0.5Ti0.25W0.25)O3. It presents a paraelectric to ferroelectrictransition at TC = 293 K, determined by permittivity measurements. The room-temperatureneutron powder diffraction pattern (NPD) shows an admixture of the ferroelectric phase (34%, P4mm space group) and the paraelectric polymorph (66%, Pm3̅m space group). In both polymorphs, the perovskite crystal structure contains the three B cations (Fe, Ti, W)distributed at random at the octahedral sites, and Pb is shifted away from the center of thecubic (sub)cell. On the other hand, the presence of iron drives the appearance of magnetic interactions above room temperature. This is related to the existence of Fe-rich islands where the strong Fe3+−O−Fe3+ superexchange interactions govern the magnetic behavior. The magnetic structure has been determined from low-temperature NPD experiments as a Gtypeantiferromagnetic (AFM) cell. Furthermore, there is a net magnetization in the entirerange of temperature, which is related to the existence of noncompensated spins in each island. The coexistence of ferroelectricity and a magnetically ordered state and the observation of a possible coupling between both phenomena allow us to suggest the multiferroic-magnetoelectric nature of the sample.We report on the crystal structure evolution and the physical properties of the complex perovskite Pb(Fe0.5Ti0.25W0.25)O3. It presents a paraelectric to ferroelectrictransition at TC = 293 K, determined by permittivity measurements. The room-temperatureneutron powder diffraction pattern (NPD) shows an admixture of the ferroelectric phase (34%, P4mm space group) and the paraelectric polymorph (66%, Pm3̅m space group). In both polymorphs, the perovskite crystal structure contains the three B cations (Fe, Ti, W)distributed at random at the octahedral sites, and Pb is shifted away from the center of thecubic (sub)cell. On the other hand, the presence of iron drives the appearance of magnetic interactions above room temperature. This is related to the existence of Fe-rich islands where the strong Fe3+−O−Fe3+ superexchange interactions govern the magnetic behavior. The magnetic structure has been determined from low-temperature NPD experiments as a Gtypeantiferromagnetic (AFM) cell. Furthermore, there is a net magnetization in the entirerange of temperature, which is related to the existence of noncompensated spins in each island. The coexistence of ferroelectricity and a magnetically ordered state and the observation of a possible coupling between both phenomena allow us to suggest the multiferroic-magnetoelectric nature of the sample.