$Nd_{2}Ba_{2}CaZn_{2}Ti_{3}O_{14.4}$: A new high dielectric constant oxide having a disordered (cubic) perovskite structure

A new oxide of the formula Nd2Ba2CaZn2Ti3O14.4 has been successfully prepared by a high-temperature ceramic route at 1200 degreesC. The title compound crystallizes in a cubic structure with a = 3.94263(7) Angstrom (space group = Pm (3) over barm, wRp = 0.0305, Rp, = 0.0192) as obtained from Rietveld refinement of powder neutron diffraction data. X-ray and electron diffraction studies also confirm the absence of any ordering of the cations. The titlen compound has a high dielectric constant of 59 at 100 kHz and a very small frequency coefficient of the dielectric constant (depsilon/dF = 1.26 x 10(-6) Hz(-1)). The dielectric loss is 0.0047 at 100 kHz, which also shows very minor variation with frequency. The temperature-dependence studies show an increase in dielectric constant and dielectric loss over the temperature range 35-300 degreesC