Unique chemical activity in porous YbB(2)C(2) ceramics with high porosity and high compressive strength

High purity layered YbB(2)C(2) powder is synthesized by a boro/carbothermic reduction method using YbBO(3), B(4)C and graphite powders as raw materials. Its X-ray diffraction data are presented, and the space group P4/mbm (No. 127) is confirmed. The lattice parameters are a = b = 5.3389 Å and c = 3.5683 Å, and the atom positions are Yb (0.0000, 0.0000, 0.0000), B (0.3621, 0.8621, 0.5000), and C (0.1606, 0.6606, 0.5000). Porous YbB(2)C(2) ceramics have a high porosity in the range of 69.89–58.11% and a high compressive strength in the range of 19.49–63.44 MPa. Furthermore, the as-produced porous YbB(2)C(2) ceramics show unique chemical activity. Porous YbB(2)C(2) ceramic with a porosity of 69.89% emits so much heat that it can burn a piece of paper when this ceramic is wetted by water. The rate of reaction between the porous YbB(2)C(2) ceramic and water can be simply controlled by adjusting the porosity. The solid reaction products are YbB(6), C and an unknown amorphous phase.