The ferroelectric insulator ${\mathrm{BaTiO}}_3$ can be electron-doped by substitution of divalent ${\mathrm{Ba}}^{2+}$ with trivalent ${\mathrm{La}}^{3+},$ creating d states at the transition-metal sites. The successive filling of the $3d$ Ti band initiates a sequence of electronic transitions. First, the system undergoes an Anderson-type insulator-to-metal-transition into a paramagnetic and metallic state, and second, a correlation-induced antiferromagnetic and insulating phase is established for La-rich concentrations. Ceramic ${\mathrm{La}}_{1-x}{\mathrm{Ba}}_x{\mathrm{TiO}}_3$ samples covering the whole concentration range were systematically examined utilizing measurements of resistivity, specific heat, and magnetic susceptibility in the temperature range $1.8<T<\mathrm{}300\mathrm{}\mathrm{K}.$ The concentration dependence of the Sommerfeld coefficient $\gamma$ and the Pauli spin susceptibility was systematically investigated. The temperature dependence of the resistivity was studied in detail. In addition a $\mathrm{}(T,x)\mathrm{}$ phase diagram of ${\mathrm{La}}_{1-x}{\mathrm{Ba}}_x{\mathrm{TiO}}_3$ was constructed.

• Received 19 October 2000

DOI:https://doi.org/10.1103/PhysRevB.64.045113