Nanosized zirconium diboride: Synthesis and properties

The thermolysis of Zr(BH4)(4) vapor at 573 and 623 K in a vacuum of 1.33 x 10(-1) Pa was studied. Nanosized zirconium diboride was produced as an X-ray amorphous powder and a crystalline film. According to electron microscopy data, the X-ray amorphous zirconium diboride powder obtained at 573 or 623 K consists of spherical particles 30-40 nm in diameter, which is in quite a good agreement with the equivalent particle diameter (similar to 35 nm) calculated from the specific surface area of ZrB2. After annealing at 1273 K, the X-ray amorphous zirconium diboride powder crystallizes into a hexagonal lattice with the unit cell parameters a = 0.3159 nm and c = 0.3527 nm. The coherent scattering length D (hkl) is similar to 27 nm. The zirconium diboride film produced at 573 or 623 K crystallizes in similar to to a hexagonal lattice with the unit cell parameters a = 0.3163-0.3168 nm and c = 0.3524-0.3531 nm. The coherent scattering length D (hkl) is similar to 14 nm. The thickness of the ZrB2 film on quartz, glass ceramics, and stainless steel is 5-7 mu m. The microhardness of the film on a stainless steel substrate under a load of 20 g is 17.8 GPa.