LAUSR

Samarium/bismuth-substituted barium lanthanum titanate ceramics with chemical composition $$ {\hbox{Ba}}_{4} ({\hbox{La}}_{1 - y - z} {\hbox{Sm}}_{y} {\hbox{Bi}}_{z} )_{9.33} {\hbox{Ti}}_{18} {\hbox{O}}_{54} $$Ba4(La1-y-zSmyBiz)9.33Ti18O54 (y = 0.5, 0.7; z = 0.05, 0.10, 0.15), intended as microwave reflecting materials, have been investigated in microwave X-band (8.2 GHz to 12.4 GHz) and the effect of substitution on their dielectric properties, i.e., dielectric constant and dielectric loss tangent, has been studied by vector network analyzer. Dielectric analysis showed that the dielectric constant increased with increasing samarium as well as bismuth content. Dielectric relaxation was observed for all samples in the scanned frequency range. Microwave reflection and transmission analysis of ceramic pellets of thickness 4 mm was carried out using two methods, i.e., open- and short-circuit approach, both indicating very high values of reflected power and very low values of transmitted power for all the doped materials in comparison with the base composition. The doped compositions are therefore potential microwave shielding materials for use in anechoic chambers, microwave laboratories, and radar equipment. Double-layer reflectors are also proposed, having better reflection properties (∼99% reflection) compared with single-layer reflectors.