Abstract:
Researching transition metal nitrides is complicated by the tendency of nitride ions convert into molecular nitrogen by oxidation at elevated temperatures. Classical solid-state chemical synthesis methods, which work at normal pressure, quickly reach their limits when it comes to producing highly oxidised and nitrogen-rich systems. These highly oxidised materials can now be produced by high-pressure synthesis, where pressures in the gigapascal range (109 Pa) generate high chemical nitrogen potentials. We were thus able to stabilise highly oxidised nitridometallates such as the Ca4FeN4 with FeIV, as well as to gain access to the new class of nitride perovskites exemplified by LaReN3. Since we use large-volume presses, we obtain larger sample quantities that are suitable for the determination of physical properties such as magnetism, magnetic structure, and electrical conductivity.