Fabrication, sintering, heat capacity, magnetic and magnetroresistivity properties of ytterbium sulfides

The preparation, sintering and low-temperature physical properties of four kinds of ytterbium sulfides (η-Yb2S3, e-Yb2S3, Yb3S4 and YbS) were systematically investigated. The suitable sintering processes were ensured for each ytterbium sulfide. SEM results suggested the sintered ytterbium sulfides had high dense. The measured susceptibility and magnetization of ytterbium sulfides suggested Yb was mainly trivalent in η-Yb2S3 and e-Yb2S3. Moreover, the magnetroresistivity of η-Yb2S3 and YbS shows semiconductor behavior. The resistivity of orthorhombic η-Yb2S3 is consistent with Kondo-like characteristic (logarithmic increase with decreasing temperature), while the ρ(T) behavior of YbS is contrast to the Kondo-like behavior. The contribution of electron, lattice and magnetism to heat capacity of ytterbium sulfides was analyzed. For η-Yb2S3, Yb3S4 and YbS, the crystal electron field (CEF) ground state is a Kramers doublet while for e-Yb2S3 it changed to quartet (Γ8). Chemical composition and crystal structure had strong influence on the heat capacity of lanthanide sesquisulfides.