Still other metals such as alkali metals including sodium, lithium and potassium may generally be one metal component in mixed metal oxides such as lithium tantalate (LiTaO3), lithium niobate (LiNbO3), Fe- or Ti-doped lithium niobate, potassium barium niobate (KBa2Nb5O15), potassium lithium niobate (K3Li2Nb5O15), potassium sodium tantalate ((K1-xNax)TaO3), K3Li2(TaxNb1-x)5O15 and the like.