First-principles study on stability, electronic, and mechanical properties of La–C and Ce–C binary compounds

Synthesis of LaCN3, TbCN3, CeCN5, and TbCN5 Polycarbonitrides at Megabar Pressures

“…The volume-pressure dependences of the DFT-relaxed structures of LaCN 3 and CeCN 5 in the pressure range of 0–120 GPa and 10–120 GPa, respectively, were fitted with a third-order Birch–Murnaghan equation of state (Figure ). The obtained bulk moduli ( K 0 (LaCN 3 ) = 192.5(6) GPa, K 0 (CeCN 5 ) = 250.7(14) GPa) are higher than the bulk moduli of known nitrides and carbides of lanthanum (LaN, La 2 C 3 , LaC 2 ) and cerium (CeN, CeC, Ce 2 C 3 , CeC 2 ) due to the presence of robust polycarbonitride 3D frameworks with relatively incompressible short C–N and N–N bonds. At the same time, the obtained bulk moduli are lower than the bulk moduli of the ultraincompressible C–N solids, likely because of the dilution of the C–N framework with metal ions.…”

“…The obtained bulk moduli (K 0 (LaCN 3 ) = 192.5(6) GPa, K 0 (CeCN 5 ) = 250.7(14) GPa) are higher than the bulk moduli 6) GPa, and K p = 4.214 (12), while for CeCN 5 , they are V 0 = 239.98(9) Å 3 , K 0 = 250.7( 14) GPa, and K p = 4.14 (3). ) and cerium (CeN, 60 CeC, 59 Ce 2 C 3 , 59 CeC 2 59 ) due to the presence of robust polycarbonitride 3D frameworks with relatively incompressible short C−N and N−N bonds. At the same time, the obtained bulk moduli are lower than the bulk moduli of the ultraincompressible C−N solids, 17 likely because of the dilution of the C−N framework with metal ions.…”

Calcination-Free Synthesis of Porous Metal Oxides/Carbon from Calcium Carbide by Ball Milling

“…Specifically, the temporary extremely high temperature and pressure during high-energy ball milling might be advantageous to forming metal carbides between the activated carbon atoms and the transition elements with abundant empty d-orbitals . However, the intermediate metal carbides were unstable with 30 min of ball milling and were prone to decompose into metal oxides and carbon support, which is corroborated by the instability of MnC x , Fe 3 C, and ZnC x at room temperature, as well as the harsh production environment for CuC x , ZrC x , NbC, CeC x , HfC x , and WC (at a temperature above 1000 °C or with laser treatment).…”