Abstract
We report on structural, dielectric, magnetic and Raman data of the title compounds. Analysis of the single crystal diffraction data reveals that the ground state can be characterized within the Cm space group. The Ba4MTa10O30 compounds show typical features of incipient ferroelectrics, i.e., their dielectric constant gradually increases on cooling and levels off or slightly decreases below 10K. Nb solubility limit, x, for Ba4MNbxTa10−xO30 compositions equilibrated at 1450?1600 oC was determined. Substitution of Nb for Ta leads to the low-temperature dielectric anomaly having a relaxor-type signature. The Co- and Ni-based compounds show paramagnetic behavior in the 2?300 K.
