We report on structural, microstructural, dielectric, electrical, magnetic, and spectroscopic (Raman and terahertz) properties of lead iron tantalate $\text{Pb}\left({\text{Fe}}_{1/2}{\text{Ta}}_{1/2}\right){\text{O}}_3$ ceramics. Raman spectroscopy revealed the presence of nanoscale ordering though it is forbidden in bulk by crystal symmetry. The dielectric properties of $\text{Pb}\left({\text{Fe}}_{1/2}{\text{Ta}}_{1/2}\right){\text{O}}_3$ show a typical relaxor ferroelectric behavior with long-range disorder while the magnetoelectric properties show an interesting multiferroic behavior (coexistence of ferroelectric and magnetic order) in the same phase. The temperature variation in field cooled magnetization shows anomalies at about $55\left(\pm 5\right)$ and $180\left(\pm 5\right)\text{K}$ indicating the existence of two Néel temperatures in agreement with theoretical predictions. The zero-field-cooled magnetization as a function temperature and field reveals the existence of spin-glasslike behavior at low temperature like single crystal. The electrical conduction behavior satisfies the modified Schottky equation of Simmons at all fields. The ac conductivity as a function of frequency shows an excellent fit to the universal power law. Terahertz spectroscopy shows an opaque nature of $\text{Pb}\left({\text{Fe}}_{1/2}{\text{Ta}}_{1/2}\right){\text{O}}_3$ in midinfrared and far-infrared wavelengths.

• Received 11 May 2010
• Publisher error corrected 8 October 2010

DOI:https://doi.org/10.1103/PhysRevB.82.134104