Electrical behavior of aluminum nitride ceramics sintered with yttrium oxide and titanium oxide

Abstract

Electrical behavior of AlN ceramics sintered with Y2O3 as a sintering aid has been investigated with respect to additional TiO2 dopant. From the impedance spectroscopy, it was found that the grain and grain boundary conductivities have greatly decreased with addition of TiO2 dopant. The TiO2 dopant also increased the activation energy of the grain conductivity by about 0.37 eV; this increase was attributed to the formation of an associate between Al vacancies and Ti ions at the Al sites. Similarly, the electronic conductivity was reduced by TiO2 addition. However, TiO2 solubility in AlN grains was below the detection limit of typical EDX analysis. Grain boundary was clean, without liquid films, but did show yttrium segregation. The transference number of ions was close to 1, showing that AlN is a predominantly ionic conductor. Based on the observed results, the implications of using AlN applications as insulators have been discussed.