稀土多元渗法制备稀土碳化钼LnxMoyC及其导电性

RE Co-permeation Preparation and Conductivity of RE Molybdenum Carbide LnxMoyC

摘要:

为扩大碳化钼在导电材料方面的应用，研究稀土碳化钼LnxMoyC的制备方法及其导电性。采用稀土多元渗法，以(NH4)3[CrMo6O24H6]·7H2O为前驱体制备LnxMoyC。用X射线衍射、电子探针X射线能谱、光电子能谱和四探针电极等手段对其结构、元素含量、价态及电性能等进行测试。结果表明：生成的LnxMoyC是六方密堆结构；渗入的微量稀土元素对其导电性产生了影响；La0.00593Nd0.00562Sm0.00502Gd0.00500Mo1.98C(简写为LNSGMC)的室温电导率（4.692×102 S·cm-1）比用传统方法得到的最高值（1.025×102 S·cm-1）高近4.6倍，且在289~490 K范围内其表现出金属导电行为，在490~550 K范围内却表现出显著的半导体导电行为。

Abstract:

In order to extend the application of Mo2C as electric materials, the preparation of RE molybdenum carbide LnxMoyC by means of rare earth co-permeation with (NH4)3[CrMo6O24H6]·7H2O as the precursor and its conductivity were studied. XRD, EDS, XPS and four-probe poles were used to characterize the structure, element content, valences and conductivity of LnxMoyC. Results show that the structure of the prepared LnxMoyC is single hexagonal close-packed (hcp) and some rare earth elements such as Nd, Gd, La and Sm permeated into crystal phase of molybdenum carbide have influence on its conductivity. The conductivity of LNSGMC (La0.00593Nd0.00562Sm0.00502Gd0.00500Mo1.98C ) at room temperature is 4.692×102 S·cm-1, which is 4.6 times higher than the highest value (1.025×102 S·cm-1) by conventional methods. In the range of 289-490 K, it shows metallic conductivity while in 490-550 K range it shows obvious semiconductor conductivity.