Magnetic and calorimetric studies on rare-earth iron borates LnFe3(BO3)4 (Ln = Y, La-Nd, Sm-Ho)

A series of rare-earth iron borates having general formula LnFe(3)(BO3)(4) (Ln =Y, La-Nd, Sm-Ho) were prepared and their magnetic properties have been investigated by the magnetic susceptibility, specific heat, and Fe-57 Mossbauer spectrum measurements. These borates show antiferromagnetic transitions at low temperatures and their magnetic transition temperatures increase with decreasing Ln(3+) ionic radius from 22K for LaFe3(BO3)(4) to 40K for TbFe3(BO3)(4). In addition, X-ray diffraction, specific heat, and differential thermal analysis (DTA) measurements indicate that the phase transition occurs for the LnFe(3)(BO3)(4) compounds with Ln = Eu-Ho, Y, and its transition temperature increases remarkably with decreasing Ln3+ ionic radius from 88 K for Ln = Eu to 445 K for Ln = Y. (C) 2003 Elsevier Science (USA). All rights reserved.