Low-temperature precipitation in NaCl: Eu++ monocrystals

It has been shown that the macroscopic features of the as grown NaCl crystals containing up to about 140 m ppm of Eu++ ions agree well with the main characteristics of the Na2EuCl4 phase present in these crystals. Thermal decomposition of the NaCl:Eu++ solid solution leads to the formation of the mentioned Na2EuCl4 phase at temperatures not very much higher than 273 K. The kinetics of this process is governed by the pipe diffusion which leads to the growth of the small impurity aggregates already present in quenched samples.