Defect properties of mechanically alloyed La-substituted PbWO4

Mechanical alloying (MA) technique has been applied to prepare the PbWO4-based scheelite-type solid solutions at room temperature. In the case of La-substitution, the scheelite-type single phase can be obtained by 12 h milling. The solubility range of lanthanum ions was 0≤x≤0.4 in the form Pb1−xLaxWO4+x/2 and 0≤x≤1.0 in the composition of Pb1−xLa2x/3WO4. The latter case includes La2/3WO4, which cannot be obtained by the conventional sintering method. From the powder density measurements, the mechanically alloyed samples were supposed to prefer the charge compensation by forming cation vacancy rather than by forming oxide ion interstitials, in these lanthanum-substituted PbWO4s.