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NbB2 is hexagonal omega structure structured and crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Nb is bonded to twelve equivalent B atoms to form a mixture of face and edge-sharing NbB12 cuboctahedra. All Nb–B bond lengths are 2.45 Å. B is bonded in a 9-coordinate geometry to six equivalent Nb and three equivalent B atoms. All B–B bond lengths are 1.80 Å.
The various reactions that are possible between hydrogen and certain ceramic materials are discussed as well as the means of measuring the extent of such reactions. Powdered carbides, nitrides, borides, and oxides were tested. These materials were heated inductively in a tungsten cup between 4000 and 4500 F for two 1-hour periods under a static hydrogen atmosphere. Weight, pressure, and diffraction pattern changes were observed, and these served to indicate the extent of reaction. Most of the ceramics, HfC, ZrC, TiC, TaC, NbC, WC, MO2C, HfN, ZrN, NbN, ZrB2, NbB2, and WB, showed less reaction than the minimum detectable value. However, the ceramics, TiN, TaN, HfB2, TiB2, ZrO2, and Cr2O3, apparently reacted to a measurable extent with hydrogen. Reactions of SiC, VC, and TaB2 with hydrogen were not determinable because of their incompatibility with the tungsten container.