Magnetic and calorimetric studies on rare-earth iron borates LnFe 3(BO 3) 4 ( Ln=Y, La–Nd, Sm–Ho)

Abstract

A series of rare-earth iron borates having general formula LnFe 3(BO 3) 4 ( Ln=Y, La–Nd, Sm–Ho) were prepared and their magnetic properties have been investigated by the magnetic susceptibility, specific heat, and 57Fe Mössbauer spectrum measurements. These borates show antiferromagnetic transitions at low temperatures and their magnetic transition temperatures increase with decreasing Ln 3+ ionic radius from 22 K for LaFe 3(BO 3) 4 to 40 K for TbFe 3(BO 3) 4. In addition, X-ray diffraction, specific heat, and differential thermal analysis (DTA) measurements indicate that the phase transition occurs for the LnFe 3(BO 3) 4 compounds with Ln=Eu–Ho, Y, and its transition temperature increases remarkably with decreasing Ln 3+ ionic radius from 88 K for Ln=Eu to 445 K for Ln=Y.