While reading a paper, I got a intresting finding. The paper is about a magnetic refrigerant bought from a chinese company Baotou Steel and Rare Earth Company of China. In a section, the researcher anaylsed the elements of the material. Even tough the company claimed it is 99.9% pure, but actually it is 93% (99.7% wt.%) which is not so pure. Then its performance is slightly inferior to the data from Ames Laboratory. However, then the researcher compared the price of the Chinese material with the material used in the Ames Laborotory, which are $110/kg and $23,000/kg, respectively. Very happy to use chinses product.
paper: Zimm, C., A. Jastrab, A. Sternberg, V. Pecharsky, K. Gschneidner, M. Osborne, and I. Anderson. “Description and performance of a near-room temperature magnetic refrigerator.” In Advances in cryogenic engineering, pp. 1759-1766. Springer, Boston, MA, 1998.