A dielectric material, Zr0.10Ta0.90O2.45, with a noncentrosymmetric L-Ta2O5-related structure

Abstract

A dielectric material with a noncentrosymmetric L-Ta2O5-related structure, Zr0.10Ta0.90O2.45, was synthesized through a solid-state reaction using Ta2O5 and ZrO2 powders, followed by a 1700 °C heat treatment. The structure was determined to have a C-centered orthorhombic symmetry [a = 6.3717(2) Å, b = 10.8003(4) Å, c = 3.87058(12) Å], and is denoted as L′-Ta2O5. The possible space groups are C222, Cmm2, C2mm, or Cm2m. The L′-Ta2O5-type Zr0.10Ta0.90O2.45 has a strong second-harmonic generation signal and higher dielectric constant of 55, compared to conventional L-Ta2O5-related structures. High-temperature x-ray diffraction shows the phase transition to the L″-Ta2O5 phase with a pseudo-hexagonal structure around 400 K. The temperature dependence of the dielectric constant reveals that the phase has a maximum value of 60, which is attributed to the phase transition. Zr0.10Ta0.90O2.45 is a potential candidate for application in complementary metal–oxide–semiconductor-compatible devices using noncentrosymmetric materials.