Ferroelectric Properties of Tungsten-Bronze Oxides with A2 A'Ta5O15 Type

Dielectric properties of oxides with the tungsten bronze structure were investigated. Confirmations of the ferroelectric activity were carried out in the ceramic samples having general chemical formulae A 2 A 'Ta 5 O 15 , where A =Ba, Ca and Sr, A '=Na and K, and in the single crystals of Ba 2 NaTa 5 O 15 and the mixed system Ba 2 NaNb 5(1- x ) Ta 5 x O 15 . As the result, the empirical relationship was established that the Curie point of tantalates is lower than that of niobates in the tungsten-bronze family ferroelectrics.