Exploration of crystal structures and phase transitions in Hf3N4. Issue 19 (26th April 2017)

• Record Type: Journal Article
• Authors: Zheng, Feng; Fang, Yimei; Yu, Shu; Wu, Shunqing; Zhu, Zi-zhong
• Is Part Of: CrystEngComm. Volume 19:Issue 19(2017)
• Page Start: 2608
• Page End: 2613
• Publication Date: 2017-04-26
• Subjects: Crystals -- Periodicals; Crystal growth -- Periodicals; Crystallography -- Periodicals; Cristaux -- Périodiques; Cristaux -- Croissance -- Périodiques; Cristallographie -- Périodiques; 548
• DOI: 10.1039/c7ce00524e
• Languages: English
• ISSNs: 1466-8033

Abstract

Abstract : Using the adaptive genetic algorithm (AGA) crystal structure prediction method, we explored the stable/meta-stable phases of Hf3 N4 . Abstract : Using the adaptive genetic algorithm (AGA) crystal structure prediction method, we explored the stable/meta-stable phases of Hf3 N4 . A new ground-stage phase ( C 2/ m ) of Hf3 N4 at ambient pressure was predicted. Calculated phonon dispersion and elastic constants of this phase showed it to be dynamically and mechanically stable. We also produced a pressure–temperature phase diagram of Hf3 N4 that included the C 2/ m, orthorhombic Zr3 N4 -type ( Pnam ) and I 4̄3 d phases. Our results revealed that increasing the pressure and temperature would transform the C 2/ m phase of Hf3 N4 to the I 4̄3 d and Pnam phases, respectively. Although the orthorhombic Zr3 N4 -type phase was indicated to be metastable over all pressures, the contributions from its larger vibrational entropies than for C 2/ m indicated it to be stable only between temperatures of ∼414 and ∼686 K at low pressure. The I 4̄3 d structure was calculated to be stable at a wide range of temperatures at high pressure and at a wide range of pressures at high temperature, with this result being in good agreement with the experimental results.