Cold working of sodium metal converts body centred sodium metal to a mixture of a hexagonal form and body centred sodium at 5 K. The hexagonal from converts back to the body-centred form at 100-100 K.

Cold working of lithium metal converts body centred lithium metal to a mixture of a hexagonal form and body centred lithium at 78 K.

Potassium, rubidium, and caesium retain their body centred structure after cooling

X-ray study of the alkali metals at low temperatures, Barrett, C. S. , Acta Crystallographica, 08/1956, Volume 9, Issue 8, p.671 - 677, (1956)

Crystal structure of uranium nitride, UN. The structure is face-centered cubic with a lattice constant of 4889 ± 0.001 Å at 26°C and sodium chloride type. The theoretical density is 14315 kg m^–3, and the U—N bond distance for coordination number 6 is 2.4449 Å.

Crystallographic Data. 177. Uranium Mononitride, Kempter, Charles, McGuire Joseph, and Nadler M. , Analytical Chemistry, 01/1959, Volume 31, Issue 1, p.156 - 157, (1959)

ScCl₃, TiCl₃ und VCl₃ kristallisieren hexagonal-rhomboedrisch in dem gleichen Gitter wie FeCl₃ (DO₅-Typ).

Die Kristallstrukturen von ScCl3, TiCl3 und VCl3, Klemm, Wilhelm, and Krose Ehrhard , Zeitschrift für anorganische Chemie, 05/1947, Volume 253, Issue 3-4, p.218 - 225, (1947)

Abstract.The structure of isomer 2 of Tb₃N@C₈₄ has been determined through single-crystal X-ray diffraction on Tb₃N@C₈₄·NiII(OEP)·2(C₆H₆). The carbon cage has a distinct egg shape due to the presence of a single pair of fused pentagons at one apex of the molecule. Thus, although 24 IPR structures are available to the C₈₄ cage, Nature utilizes one of the 51 568 isomeric structures that do not conform to the IPR for this unusual molecule. The Tb3N portion of isomer 2 of Tb₃N@C₈₄ is strictly planar. One Tb atom is nestled within the fold of the fused pentagons, while the other Tb atoms are disordered over four pairs of sites.

Tb3N@C84 :  An Improbable, Egg-Shaped Endohedral Fullerene that Violates the Isolated Pentagon Rule, Beavers, Christine M., Zuo Tianming, Duchamp James C., Harich Kim, Dorn Harry C., Olmstead Marilyn M., and Balch Alan L. , Journal of the American Chemical Society, 09/2006, Volume 128, Issue 35, p.11352 - 11353, (2006)

BuckyEgg Tb₃N@C₈₄: image credit Mark Winter

Ozone. Credit Mark Winter

Gypsum, cover from Geology; April 2007; v. 35; no. 4; p. 327-330; DOI: 10.1130/G23393A.11

1. 1. Formation of natural gypsum megacrystals in Naica, Mexico,
   García-Ruiz, Juan Manuel, Villasuso Roberto, Ayora Carlos, Canals Angels, and Otálora Fermín
   , Geology, 2007, Volume 35, Issue 4, p.327, (2007)
   

Polonium metal crystal structure

Polonium dioxide

Polonium dichloride crystal structure