Synthesis and dielectric properties of thin-layered (La,Nd)TiO₂N perovskites

Dielectric measurements made on thin layers of oxynitride of composition (La,Nd)TiO₂N deposited on substrates of the equivalent pure oxides gave high and variables values for the relative permittivity, and very high values of dielectric loss, showing that the samples were significantly conducting. This is believed to be due to reduction taking place during the nitridation step, the use of ammonia (by far the most convenient and effective nitriding agent for this purpose) resulting in the simultaneous production of active atomic hydrogen which easily diffuses through both the surface oxide and the simultaneously forming layer of oxynitride to give compositions of the type (La,Nd)₂Ti^IV_2-xTi^III_xO_7-x/2 and La_xNd_1-xTi⁴⁺_1-yTi³⁺_yO2_-y/2N respectively. It is well established that the presence of Ti³⁺ in titanium oxides and oxynitrides readily promotes conductivity. These results explain the diverse dielectric property measurements reported by previous researchers working on oxynitride materials, and show that alternative nitridation methods are needed in order to determine correct values of dielectric properties of pure oxynitride materials.