Altering magnetic and optical features of rare earth orthoferrite LuFeO3 ceramics via substitution of Ir into Fe sites

Abstract

LuFeO3 and LuFe1-xIrxO3 ceramics with x ​= ​0.05 and 0.10 have been obtained by solid-state reaction process. Scanning electron microscope (SEM) analyses have revealed the existence of both particle agglomeration and porosity of nature of the studied samples. The X-ray photoelectron spectroscopy (XPS) investigations have revealed that while Lu has 3+, Fe has mix valence states, 2+ and 3+. On the other hand, the Ir dopant has metallic and 4+ valence states in the study samples. The Raman investigations unveiled i) the Raman peak intensity reduces with Ir doping until ∼600 ​cm−1, ii) the peaks appearing between 200 ​cm−1 and 600 ​cm−1 wavenumbers shift toward the smaller values. Magnetic measurements, conducted by vibrating sample magnetometer (VSM), have shown the spin re-orientation (SR) transition temperature around 47 ​K for all the investigated samples. Furthermore, it is noticed the 5 ​mol % Ir doped sample has higher magnetization than other samples owing to existence of magnetic impurities such as Lu3Fe5O12. M ​− ​H loops have unveiled that Ir doping advances both Hc and Mr values compared to the undoped LFO sample. This increase in both Hc and Mr values could be due to 1) the variation of the canted angels of Fe3+ moments, 2) the advancement of energy of magnetocrystalline anisotropy, and 3) formation of secondary phases such as Lu3Fe5O12 and Fe3O4. Furthermore, the optical band gap examinations have revealed that the band gap of LFO reduces from 2.19 ​eV to 2.