Differential thermal/thermogravimetric analysis (DTA-TG) and thermal expansion anomaly properties of Tm2Fe17 compound

The structure, the magnetic and thermal expansion properties of Tm
2
Fe
17
compound and its nitrides have been investigated by means of x-ray diffraction, magnetization measurements and Simultaneous Thermal Analyzer as well. The result shows that with the temperature increasing from 200K to 1200K under the protection of N
2
, Tm
2
Fe
17
N
x
compound is formed due to the diffusion of the interstitial N atoms. There appears a higher Curie temperature in Tm
2
Fe
17
N
x
compound than its mother compound Tm
2
Fe
17
. At higher temperature than 650K, the nitrogenized reaction of Tm
2
Fe
17
is sufficient, in the meantime, the decomposed reaction of Tm
2
Fe
17
N
x
whose by-products include α − Fe takes place. The structure analysis indicates that Tm
2
Fe
17
N
x
compound exhibits only single phase of Th
2
Ni
17
below 1200K. The investigation of thermal expansion shows there exits an anisotropic negative thermal expansion in the temperature range from 300K to 340K, and the coefficient of the average thermal expansion is α̅ = −1.92×10
⁻⁵
/K.