Influence of the Multiplet Levels of Sm3+ and Eu3+ on the Heat Capacity of Multiferroic BiFeO3

Abstract

The temperature dependence of the heat capacity of multiferroics BiFeO 3 , Bi 0.90 Sm 0.10 FeO 3 , and Bi 0.90 Eu 0.10 FeO 3 has been investigated. It is found that the substitution of bismuth ions with europium and samarium ions in bismuth ferrite leads to the appearance of an additional heat capacity component due to the transitions of 4f electrons of rare earth ions to higher multiplet levels. A relationship is established between the decrease in phonon thermal conductivity and the Schottky effect for the specific heat.

Heat capacity of nanostructured SmFeO-=SUB=-3-=/SUB=-

“…Crystal lattice vibrations can bring RE ions to the overlying layers and this leads to a decrease in the heat capacity due to thermal excitation of 4 f -electrons of rare earth elements (REE), i.e. to Schottky effect and reduction of crystal lattice heat capacity as a result of resonant phonon scattering on paramagnet RE ions [14]. Therefore, the presence of an additional heat capacity component in samarium ferrite can be associated with transition of RE ion 4 f -electrons to higher levels.…”