We have measured the electrical resistivity, specific heat, magnetic susceptibility, magnetization, magnetoresistance and de Haas-van Alphen effect to clarify the magnetic and elecrtical properties of NdCu2. The magnetic phase diagram is presented for the field along the b-axis, which consists of five or more magnetic phases. The Fermi surface of NdCu2 is not similar to that of YCu2 nor to that of CeCu2. Cyclotron masses of NdCu2 range from 0.4 to 1.5 m(0), which are larger than 0.1-0.7 m(0) in YCu2, but smaller than 0.5-5.3 m(0) in CeCu2.
Thermal studies on oxidation–reduction of LnCu2 intermetallic compounds and their catalytic behavior for 2-propanol decomposition
作者:Joaquim B. Branco、Catarina J. Dias、António Pereira Gonçalves
DOI:10.1016/j.jallcom.2008.11.113
日期:2009.6
the binary intermetallic compounds LnCu 2 decompose into a copper–rare earth oxide phase that after reduction leaves their surface highly enriched on the copper. The structure of the oxidized and reduced intermetallics can best be described as copper embedded in lanthanide oxides (Ln 2 O 3 ) or “type supported catalysts” and exhibited activity for the 2-propanol oxidative dehydrogenation–dehydration reaction
摘要 对二元金属间化合物 LnCu 2 (Ln = La、Ce、Pr、Nd、Eu、Gd、Dy、Tm、Yb) 进行了高温氧化还原研究。通过沿镧系元素系列的 O 2 -TG 和 H 2 -TG 或 H 2 -TPR 研究优化了两步循环。氧化质量吸收发生在很宽的温度范围内(200-900 °C),根据镧系元素产生两种双金属铜-镧系元素氧化物家族:3CuO·Ln 2 CuO 4 (Ln = La, Pr, Nd, Eu, Gd) 和 2CuO·Ln 2 Cu 2 O 5 (Ln = Dy, Tm, Yb),除了产生 2CuO·CeO 2 的 CeCu 2 。在氢气下,所有系统都表现出两个还原步骤,并在 150-600°C 的温度范围内伴随着质量损失。第一个质量损失与 CuO 的减少有关,而第二个质量损失对应于 Ln 2 CuO 4 或 Ln 2 Cu 2 O 5 相中铜的减少,伴随着 Ln 2 O