From the category of NdFeB, the materials VACODYM
655 HR and VACODYM 722 HR (VACUUMSCHMELZE
GmbH) are considered as two options. The comparison of
magnetic properties of these two materials is given in Table
1 [12]. It can be seen that the magnetic material
VACODYM 722 HR has a higher energy density compared
to VACODYM 655 HR. Furthermore, the magnetic
material VACODYM 722 HR can be used in the magnetic
scroll expander under the room temperature conditions
between -20C and +30C, and the material VACODYM
655 HR can be used at higher temperature up to +120C.
Figure 4 shows the datasheet of the VACODYM 655 HR,
which has higher reversible magnetic field operations
compared to the VACODYM 722 HR.