Chemistry:Hafnium nitrides

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Short description: Class of chemical compounds

The hafnium nitrides are the various salts produced from combining hafnium and nitrogen. The two most important such are hafnium(III) nitride, HfN; and hafnium(IV) nitride, Hf3N4. None can be prepared from hafnium oxide, but must instead be prepared from the elemental metal or a different hafnium nitride salt; attempted nitridation of the oxide gives an oxynitride instead.[1]

HfN is refractory and generally produced as a thin film coating,[2] although zone annealing gives the bulk material.[3] HfN adopts the rock-salt crystal structure.[2] The surplus hafnium electron delocalizes, so that HfN is a metal, conducting at room temperature and superconducting below 8.8 K (−443.83 °F). Its bright gold color is a cheaper alternative to gilding.[4]

The dark red semiconductor Hf3N4 does not form at room temperature, but requires high pressure, high temperature synthesis in a diamond anvil cell. At 18 GPa (180,000 atm) and 2,800 K (4,580 °F), it adopts the cubic crystal structure and repeats according to space group I43d.[2] At lower pressures, the cubic structure is believed metastable, decaying to the orthorhombic structure of zirconium(IV) nitride.[4][5] That structure forms outright at 19 GPa and 2,000 K (3,140 °F), and another metastable tetragonal structure forms at 12 GPa and 1,500 K (2,240 °F). Computational studies suggest that it may catalyze polymerization of nitrogen at very high temperatures, through a catenary anion in HfN10.[5]

In systems with limited nitrogen, hafnium also forms Hf3N2, as well as a solid solution hafnium alloy.[6]

References

  1. ↑ Bazhanov, D. I.; Knizhnik, A. A.; Safonov, A. A.; Bagatur’yants, A. A.; Stoker, M. W.; Korkin, A. A. (2005-02-15). "Structure and electronic properties of zirconium and hafnium nitrides and oxynitrides" (in en). Journal of Applied Physics 97 (4). doi:10.1063/1.1851000. ISSN 0021-8979. Bibcode: 2005JAP....97d4108B. https://pubs.aip.org/jap/article/97/4/044108/914354/Structure-and-electronic-properties-of-zirconium. 
  2. ↑ 2.0 2.1 2.2 Zerr, Andreas; Miehe, Gerhard; Riedel, Ralf (2003-03-01). "Synthesis of cubic zirconium and hafnium nitride having Th3P4 structure" (in en). Nature Materials 2 (3): 185–189. doi:10.1038/nmat836. ISSN 1476-1122. PMID 12612677. https://www.nature.com/articles/nmat836. 
  3. ↑ Christensen, A. Nørlund; Kress, W.; Miura, M.; Lehner, N. (1983-07-15). "Phonon anomalies in transition-metal nitrides: HfN" (in en). Physical Review B 28 (2): 977–981. doi:10.1103/PhysRevB.28.977. ISSN 0163-1829. Bibcode: 1983PhRvB..28..977C. https://link.aps.org/doi/10.1103/PhysRevB.28.977. 
  4. ↑ 4.0 4.1 Kroll, Peter (2003-03-25). "Hafnium Nitride with Thorium Phosphide Structure: Physical Properties and an Assessment of the Hf-N, Zr-N, and Ti-N Phase Diagrams at High Pressures and Temperatures" (in en). Physical Review Letters 90 (12). doi:10.1103/PhysRevLett.90.125501. ISSN 0031-9007. PMID 12688881. Bibcode: 2003PhRvL..90l5501K. https://link.aps.org/doi/10.1103/PhysRevLett.90.125501. 
  5. ↑ 5.0 5.1 Zhang, Jin; Oganov, Artem R.; Li, Xinfeng; Niu, Haiyang (2017-01-18). "Pressure-stabilized hafnium nitrides and their properties" (in en). Physical Review B 95 (2). doi:10.1103/PhysRevB.95.020103. ISSN 2469-9950. Bibcode: 2017PhRvB..95b0103Z. 
  6. ↑ Ushakov, Sergey V.; Navrotsky, Alexandra; Hong, Qi-Jun; van de Walle, Axel (26 Aug 2019). "Carbides and nitrides of zirconium and hafnium". Materials (Basel: MDPI) 2019 (12): 2728. doi:10.3390/ma12172728. PMID 31454900. Bibcode: 2019Mate...12.2728U. 
Salts and covalent derivatives of the nitride ion
NH3 He(N2)11
Li3N Be3N2 BN β-C3N4
g-C3N4 		N2 NxOy NF3 Ne
Na3N Mg3N2 AlN Si3N4 PN
P3N5 		SxNy
SN
S4N4 		NCl3 Ar
K3N Ca3N2 ScN TiN VN CrN
Cr2N 		MnxNy FexNy CoN Ni3N CuN Zn3N2 GaN Ge3N4 As Se NBr3 Kr
Rb3N Sr3N2 YN ZrN NbN β-Mo2N Tc Ru Rh PdN Ag3N CdN InN Sn Sb Te NI3 Xe
Cs3N Ba3N2   Hf3N4 TaN WN Re Os Ir Pt Au Hg3N2 TlN Pb BiN Po At Rn
Fr3N Ra3N   Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
↓
La CeN Pr Nd Pm Sm Eu GdN Tb Dy Ho Er Tm Yb Lu
Ac Th Pa UN Np Pu Am Cm Bk Cf Es Fm Md No Lr



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