氮化铁薄膜晶相合成热分析及其磁性

Translated title of the contribution: Thermal analysis on crystal phase synthesis of iron nitride film and its magnetic properties

Qi Hai Lu, Xiao Li Tang, Yu Zhe Song, Xian Wei Zuo, Gen Liang Han, Peng Xun Yan, Wei Min Liu

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

The phase transition law of Fe-N system is very important for efficiently synthesizing single-phase γ'-Fe4N thin films. The γ"-FeN thin films are deposited on silicon wafers via DC reactive magnetron sputtering; some of them are stripped from the silicon wafers and measured by using the synchronous thermal analysis (TG-DSC) for studying the phase transition law of Fe-N system. The results of TG-DSC show that at a heating rate of 10℃/min, the Fe-N system has five phase transitions in a temperature range between room temperature (RT) and 800℃, i.e. I (330-415℃): γ''-FeN→ξ-Fe2N with an endothermic value of 133.8 J/g; Ⅱ (415-490℃):ξ-Fe2N→ε-Fe3N with no obvious latent heat of phase change; Ⅲ (510-562℃):ε-Fe3N→γ'-Fe4N with an exotherm value of 29.3 J/g; IV (590-636℃): γ'-Fe4N→γ-Fe with an exotherm value of 42.6 J/g; V (636-690℃): γ-Fe→α-Fe with an endothermic value of 14.4 J/g. According to the phase transition law of Fe-N system, the crystal phase of iron nitride thin film is effectively regulated by vacuum annealing. The x-ray diffraction pattern (XRD) results show that the iron nitride thin film obtained by direct-sputtering in pure N2 is a single-phase γ"-FeN film, and it becomes a single-phase ξ-Fe2N film after being annealed at 350℃ for 2 h, a single-phase ε-Fe3N film after being annealed at 380℃ for 2 h, and a single-phase γ'-Fe4N film after being annealed at 430℃ for 7 h. The annealing temperature for the phase transition of Fe-N thin film is generally lower than that predicted by the TG-DSC experimental results, because it is affected by the annealing time too, that is, prolonging the annealing time at a lower temperature is also effective for regulating the crystal phase of Fe-N thin film. The magnetic properties of the Fe-N thin film are also studied via vibrating sample magnetometer (VSM) at room temperature. The γ'-Fe4N polycrystalline thin film shows an easy-magnetized hysteresis loop for the isotropic in-plane one, but a hard-magnetized hysteresis loop with a large demagnetizing field for the out-of-plane one, which belongs to the typical magnetic shape anisotropy. However, their saturation magnetizations are really the same (about 950 emu/cm3) both in the plane and out of the plane.

Translated title of the contributionThermal analysis on crystal phase synthesis of iron nitride film and its magnetic properties
Original languageChinese (Traditional)
Article number118101
JournalWuli Xuebao/Acta Physica Sinica
Volume68
Issue number11
DOIs
StatePublished - 5 Jun 2019
Externally publishedYes

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