LAUSR

Single-phase La-substituted bismuth ferrite (Bi1−x$_{\boldsymbol {1-x}}$Lax$_{\boldsymbol {x}}$FeO3$_{\mathbf {3}}$) nanoparticles have been synthesized by thermal decomposition of a glyoxylate precursor. The crystal structure transition of BiFeO3$_{\mathbf {3}}$ from the rhombohedral (R3c) to the cubic Pm3̄m$\boldsymbol {Pm}\bar {\mathbf {3}}\boldsymbol {m}$ structure by La addition was confirmed by X-ray diffraction and infrared spectrometry methods. Furthermore, the Bi1−x$_{\boldsymbol {1-x}}$Lax$_{\boldsymbol {x}}$FeO3$_{\mathbf {3}}$ nanoparticles showed a weak ferrimagnetism behaviour, while the magnetization increased from 0.18 to 0.48 emu g−1$^{\mathbf {-1}}$ with La substitution. The Bi1−x$_{\boldsymbol {1-x}}$Lax$_{\boldsymbol {x}}$FeO3$_{\mathbf {3}}$ nanoparticles exhibited strong absorption in the visible region with the optical band gap calculated from Tauc’s plot in the range of 2.19–2.15 eV. Furthermore, the effects of La substitution on the photodegradation of the methylene blue (MB) under visible light were also studied. The photodegradation of MB dye was enhanced from 64 to ∼$\sim $99% with increasing La substitution from x=$\boldsymbol {x =}$ 0 to 0.1 and then decreased to 8% for x=$\boldsymbol {x =}$ 0.15.