Diagnostics of LATGS single crystals doped with Pt(IV) ions and L-alanine for infrared applications

A novel type of full-faceted single crystals of triglycine sulfate (TGS) with various contents of Pt(IV) complex-forming ions and L-alanine were grown from aqueous solutions by means of the low cooling method. On the samples prepared from <110> pyramids we measured the main physical properties, in particular: spontaneous polarization P_s, values of coercive field E_c, internal electrical field E_b, dielectric permittivity ε_T, dielectric losses tanδ, domain structure and hysteresis loops. We found that the prepared Pt-doped crystals possess good and reproducible physical properties, structural homogeneity and low internal strain. The value of E_b, important for detector construction, can be adjusted by Pt(IV)-ion concentration in the growth solution. Based on these experimental results, a reproducible growth procedure operating at constant temperature and employing a special three-zone flow crystallizer was designed. The pyroelectric detectors prepared from these materials have been tested from the point of view of current-voltage response.