Thermal Expansion of Alkaline-Doped Lanthanum Ferrite Near the Néel Temperature



The thermal expansion and magnetic behaviors of divalent, alkaline-doped lanthanum ferrites (La0.9M0.1FeO3, M=Ca, Sr, Ba) were assessed using a combination of dilatometry, magnetometry, time-of-flight neutron diffraction, and high-temperature X-ray diffraction. Néel temperatures were determined through vibrating sample magnetometry and correlated well with changes in thermal expansion behavior observed during both dilatometry and X-ray diffraction. The Néel temperatures observed for pure, Ca-doped, Sr-doped, and Ba-doped lanthanum ferrites were 471°C, 351°C, 465°C, and 466°C, respectively. The effect of divalent substitutions on the magnetic behavior are attributed to charge compensation mechanisms and structural changes in the material.