| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1993: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1992: ¥1,300,000 (Direct Cost: ¥1,300,000)
|
|---|
| Research Abstract |
Purification of neodymium and lanthanum, removal of non-metallic and metallic impurifies from their rods, has been examined by the conventional electron beam floating zone melting (EBFZM) technique in a high vacuum and furthermore by two types of the novel advanced EBFZM techniques. In case of the latter, EBFZM treatments have been done in the atmosphore of low pressure of hydrogen (P_<H2>=10^<-3> to 10^<-5> Pa) and with a superimposed DC electric current (500 to 1000 A/cm^2) on the sample rods, respectively.
After the conventional EBFZM treatment, carbon and sulfur contents are found to be reduced by their distribution caused by the zone pass, while the reduction of exygen and nitrogen contents are scarcely observed for neodymium and lanthanum. Metallic impurities having vapor pressures higher than neodymium and lanthanum, such as calcium and magnesium, can be removed through the vaporization. While the reduction of iron, sillicon and copper are not possible through vaporization, but they can be redistributed during zone passes. The residual resistivity ratios of neodymium and lanthanum increased after the EBFZM as a result of the decrease of respective impurities.
On the other hand, the advanced EBFZM techniques are expected to be more effective for reduction of non-metallic impurities from Nd and La than the conventional one. However it is recognized that we should, first of all, investigate and find out the good conditions for the stable zone melting on the advanced EBFZM treatment, to utilize the purification effect of it on rare earth metals.
|
