All the
experiments were carried out in a glass beaker of 250 ml volume.
For 5 g of initial powders, 80 ml acid was used. During this
process, all oxides and boric acid were converted into the metallic
nitrates [i.e. Zn(NO3)2, B(NO3)3 and La(NO3)3] through the reac-
tions below. La-doped ZnB2O4 powder samples were also pre-
pared in a similar manner by taking the starting material in
stoichiometric ratio and adding La2O3 to the mixture.