Ferromagnetism, Antiferromagnetism and Paramagnetism in Vanadium Phosphates Prepared From Hydrothermal Conditions

Abstract

Several metal phosphate solids have been prepared from hydrothermal reaction methods that involve vanadium and either alkali metal ions or organic amine templating agents. A variety of magnetic behavior is observed, depending on the structures of the solids that are isolated. Binuclear [(VO)₂Cl₂(H₂O)₂(PhAsO₃H)₂Ph₄PCl, trinuclear [(C₂H₅NH₃)₂(V0)₃H₂O- (C₂H₅PO₃)₆, hexanuclear [(C₂H₅)₄N₂(vO)₆(H₂O)₂(C₂H₅PO₃)₆, 16-atom cluster [V₁₆O₂₀(OCH₂CCH₂O)₈(H₂O)₄ and polymeric [AVOPO₄, A= Na, NH₃ materials have been prepared. Some materials exhibit long range antiferromagnetic phase transitions that result from strong lattice interactions between magnetic centers. Ferromagnetic behavior is also observed in [H₃N(CH₂)₃NH₃(VO)₃(OH)₂(H₂O)₂(PO₄)₂ with a ferromagnetic phase transition at T_c=5K. The magnetic data are interpreted in terms of the molecular and crystallographic data.