Effect of lanthanum dopant on pyroelectric characteristics of lead germanate (Pb5Ge3O11) single crystals

In this article, the behavior of pyroelectric coefficient and spontaneous polarization with temperature have been studied for pure (LG), 0.5 wt% (LG1) and 1 wt% (LG2) lanthanum doped lead germanate (Pb5Ge3O11) single crystals. These crystals were grown by method of controlled cooling of the melt. The pyroelectric coefficient of grown crystals was measured over a temperature range 40-300 degrees C, which shows a change in sign negative to positive for LG and LG1 while for LG2 it shows only negative sign for a said temperature range. The observed results of pyroelectricity and spontaneous polarization in pure and doped materials are discussed. The comparative study of room temperature values of pyroelectric coefficient measured by various methods, spontaneous polarization and figure of merit is presented in this paper.