What is the crystal structure of Uranium boride?

Uranium boride is a boride of uranium. Uranium is a chemical element that has the symbol U and atomic number 92. It is a normal part of rocks, soil, air, and water, and occurs in nature in the form of minerals. 

Uranium boride Crystal

A bulk single crystal of UB4 (tetragonal ThB4-type of structure, melting temperature of 2500°C, approximately) with dimensions of 5 mm diameter and 40 mm length has been grown by a modified tri-arc Czochralski method in a continuously Ti-gettered atmosphere. The lattice parameters measured on the as-grown bulk single crystal are: a = 7.0764 Å and c = 3.9811 Å. The experimentally determined density of 9.46 g/cm3 coincides within the experimental error with the density value of 9.38 g/cm3 calculated from the lattice parameter data.

lt is shown that the modified triarc Czochralski method is a suitable technique to produce singlecrystals of uranium compounds with high congruentmelting point. The quality and dimensions of the UB4 single crystal is sufficient to measure bulk physical properties. Further investigations on microstructure,mag-netic and electrical properties are in progress.

Uranium boride synthesis

Currently, UB4 is mainly prepared by the direct reaction of elemental powders by fusion or sintering. It could not been widely applied due to the high oxygen affinity of metal uranium, the high cost of high-purity uranium and boron as well as the occurrence of serious segregation. Therefore, further development of UB4 synthesis method is well justified.

Reference

[1] Anthony J. Lupinetti. “ChemInform Abstract: Low-Temperature Synthesis of Uranium Tetraboride by Solid-State Metathesis Reactions.” ChemInform 33 29 (2010).

[2] Hangxu Guo. “Boro/carbothermal reduction synthesis of uranium tetraboride and its oxidation behavior in dry air.” Journal of the American Ceramic Society 102 3 (2018): 1049–1056.

[3] A. Menovsky,  J. Klaasse,  J. Franse. “The crystal growth of uranium tetraboride UB4 from the melt.” Journal of Crystal Growth 70 1 (1984): 519–522.