The hydride ion H− is stabilised by being surrounded by
electropositive elements such as
alkalis or
alkaline earths.[1] Quaternary compounds exist where nitrogen forms a complex with bonds to a transition or main group element. The hydride requires the presence of another alkaline earth element.[1]
A metal (Ti, Zr, Hf, Y) can also be ignited in an atmosphere mixing hydrogen and nitrogen, and a hydridonitride is formed exothermicly.[3]
The molten metal
flux technique involves dissolving metal nitrides and hydrides in an excess of molten alkaline earth metal, by heating till everything is molten, and then cooling until crystals form, but the metal is still liquid. Draining the liquid metal (and
centrifuging) leaves the crystals of hydridonitride behind. A eutectic molten metal allows it to be cooled more.[1]
If liquid alkali metal is used as a flux to grow a hydridonitride crystal, excess metal can be removed using
liquid ammonia.[4]
Properties
Some hydridonitride are sensitive to
water vapour in air.[5] For
non-stoichimetric compounds, as the proportion of hydrogen increases, the unit cell dimensions also increase, so hydrogen is not merely filling holes.[6] When heated to a sufficiently high temperature, hydridonitrides lose hydrogen first to form a metallic nitride or alloy.[7]
Room temperature superconductor
One Lutetium hydride doped with nitrogen is claimed to be a
room temperature superconductor at up to 21°C at a pressure of 1GPa, which is considerably lower than for other
polyhydrides.[8] This has been called "red matter"[9] as it is red under high pressure, but blue at ambient conditions.[10][11] The claim has been met with some skepticism as it was made by the same team that made similar claims retracted by Nature in 2022,[12][13][14][15][16]claimed observation of solid metallic hydrogen in 2016 as well as other allegations.[17] First attempts to replicate the results have failed.[18][19]Ashcroft suggested metallic hydrogen could superconduct in 1968[20] at great pressures and in 2004 similarly that dense group
IVa hydrides (as the new material) could also be superconductors at more accessible pressures.[21]
^Dolukhanyan, S. K.; Aleksanyan, A. G.; Shekhtman, V. Sh.; Hakobyan, H. G.; Mayilyan, D. G.; Aghadjanyan, N. N.; Abrahamyan, K. A.; Mnatsakanyan, N. L.; Ter-Galstyan, O. P. (2 July 2010). "Synthesis of transition metal hydrides and a new process for production of refractory metal alloys: An autoreview". International Journal of Self-Propagating High-Temperature Synthesis. 19 (2): 85–93.
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10.3103/S1061386210020020.
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^
abBrice, Jean-Francois; Motte, Jean-Pierre; Courtois, Alain; Protas, Jean; Aubry, Jacques (February 1976). "Etude structurale de Ca2NH par diffraction des rayons X, diffraction des neutrons et résonance magnétique nucléaire du proton dans le solide" [Structural study on Ca2NH by X-ray-diffraction, neutron-diffraction and proton nuclear magnetic-resonance in the solid]. Journal of Solid State Chemistry. 17 (1–2): 135–142.
Bibcode:
1976JSSCh..17..135B.
doi:
10.1016/0022-4596(76)90213-9.
^
abcDolukhanyan, S (May 1995). "Interaction of hafnium with hydrogen and nitrogen in the combustion regime". International Journal of Hydrogen Energy. 20 (5): 391–395.
doi:
10.1016/0360-3199(94)00059-9.
^Service, Robert F. (8 March 2023). "'Revolutionary' blue crystal resurrects hope of room temperature superconductivity". Science. 379 (6636).
doi:
10.1126/science.adh4968.
^Dickman, Matthew J.; Schwartz, Benjamin V. G.; Latturner, Susan E. (27 July 2017). "Low-Dimensional Nitridosilicates Grown from Ca/Li Flux: Void Metal Ca8In2SiN4 and Semiconductor Ca3SiN3H". Inorganic Chemistry. 56 (15): 9361–9368.
doi:
10.1021/acs.inorgchem.7b01532.
PMID28749660.
^Bailey, Mark S.; Obrovac, Mark N.; Baillet, Emilie; Reynolds, Thomas K.; Zax, David B.; DiSalvo, Francis J. (September 2003). "Ca 6 [Cr 2 N 6 ]H, the First Quaternary Nitride−Hydride". Inorganic Chemistry. 42 (18): 5572–5578.
doi:
10.1021/ic0343206.
ISSN0020-1669.
PMID12950205.
^Sichla, Th.; Altorfer, F.; Hohlwein, D.; Reimann, K.; Steube, M.; Wrzesinski, J.; Jacobs, H. (1997). "Kristallstrukturbestimmung an einer Strontium-hydrid-imid-nitrid-Phase - Sr2(H)N/SrNH bzw. Sr2(D)N/SrND - mit Röntgen-, Neutronen- und Synchrotron-Strahlung". Zeitschrift für anorganische und allgemeine Chemie (in German). 623 (1–6): 414–422.
doi:
10.1002/zaac.19976230166.
ISSN0044-2313.
^Blaschkowski, Björn; Schleid, Thomas (November 2007). "Darstellung und Kristallstruktur des Lithium-Strontium-Hydridnitrids LiSr2H2N". Zeitschrift für anorganische und allgemeine Chemie. 633 (15): 2644–2648.
doi:
10.1002/zaac.200700315.
^ALTORFER, F; BUHRER, W; WINKLER, B; CODDENS, G; ESSMANN, R; JACOBS, H (May 1994). "H−-jump diffusion in barium-nitride-hydride Ba2NH". Solid State Ionics. 70–71: 272–277.
doi:
10.1016/0167-2738(94)90322-0.
^Blaschkowski, Björn; Schleid, Thomas (August 2012). "Mixed-Valent Europium in the Nitride Hydride LiEu2NH3". Zeitschrift für anorganische und allgemeine Chemie. 638 (10): 1592.
doi:
10.1002/zaac.201204051.
^Peterson, D.T; Nelson, S.O (August 1981). "Equilibrium hydrogen pressures in the Th-N-H system". Journal of the Less Common Metals. 80 (2): 221–226.
doi:
10.1016/0022-5088(81)90095-3.