Effects of Sm and Mn co-doping on structural, optical and magnetic properties of BiFeO3 films prepared by a sol–gel technique

• (Bi1–xSmx)(Fe0.95Mn0.05)O3 films were deposited on quartz substrates by sol-gel.
• The Sm and Mn co-doping BiFeO3 thin films result in structural distortion.
• The optical band gap of the thin films could be tuned by the Sm content.
• The thin films have potential applications in storage and optoelectronic devices.

Multiferroic (Bi1−xSmx)(Fe0.95Mn0.05)O3 (xBSFMO, x=0.00, 0.03, 0.06, and 0.09) films were deposited on the quartz substrates by a sol–gel technique. X-ray diffraction patterns indicate that all the films exhibit a polycrystalline perovskite structure with a high degree of (110) preferred orientation. The Sm and Mn co-doping at A- and B-site of BiFeO3 (BFO) results in structural distortion, improves surface morphology and reduces the average grain size of the films. With increasing x from 0.00 to 0.09, the optical band gap of xBSFMO films increases and can be expressed by (2.60+0.8x) eV, which may be due to Burstein–Moss effect. Compared with Mn-doped BFO film, the saturation magnetization (MS) of the (Sm, Mn) co-doped BFO films are significantly enhanced, which provides potential applications in information storage.