Sol-gel preparation and electrical behaviour of Ln:YAG (Ln = Ce, Nd, Ho, Er)

A sol-gel method has been developed to prepare pure yttrium aluminum garnet, Y3Al5O12 (YAG), and rare-earth substituted (Ce-Y3Al5O12, Nd-Y3Al5O12, Ho-Y3Al5O12, and Er-Y3Al5O12) samples. The XRD patterns of the polycrystalline powders sintered at 1000 T showed the formation of monophasic garner materials. The micro-structural features in the polycristalline samples were studied by scanning electron microscopy A homogeneous distribution of rare-earth dopants in the YAG lattice was achieved in all of the cases. Electrical conductivity measurements were also performed on the compacts of sol-gel derived Ln-YAG samples. In contrast to the expected dielectric behaviour, the conducting properties of the examined specimens indicate metallic behaviour with the resistivity increasing gradually with increasing temperature.