Copper (II) oxide as a giant dielectric material

Abstract

Bulk copper (II) oxide (CuO), heat treated at 1223K, shows extraordinarily high dielectric constant (εr∼104), almost independent of temperature (above 230K) and frequency in the kilohertz region. A sudden decrease of εr is observed at lower temperature (below 150K). X-ray photoelectron spectroscopy and high resolution transmission electron microscopy studies confirm the presence of a microscopic amount of Cu3+ in annealed CuO. The dielectric behavior of CuO can be explained by Maxwell-Wagner-type polarization mechanism and thermally activated mechanism.

High Dielectric Permittivity and Maxwell–Wagner Polarization in Magnetic Ni0.5Cu0.3Zn0.2Fe2O4 Ceramics

“…In the present work, we refer to it as the Maxwell-Wagner relaxation. The overall dielectric behavior is similar to that observed in CaCu 3 Ti 4 O 12 [15][16][17], Li x Ti y Ni 1−x−y O [18,19], and CuO [20][21][22][23]. It is found that, at fixed frequency, the characteristic temperature and its relaxation peak of all the NCZFO samples move to the lower temperature ranges when sintering temperature increases, while the values of the ε for each sample above the characteristic temperature have a little change.…”

Dielectric properties of iron doped calcium copper titanate, CaCu2.9Fe0.1Ti4O12

“…8, can be divided into two Gaussian bands with maxima at 529.2 eV and 531.1 eV. Similar results have been observed for CuO [26,27], 0.65Pb(Mg 1/3 Nb 2/3 )O 3 -0.35PbTiO 3 single crystal [28] and thin films of Ba 0.5 Sr 0.5 TiO 3 [29]. Two peaks may correspond to two types of oxygen ions.…”

“…In a photoelectron emission process, electron charges are transferred from the surrounding to the core holes. Such a situation causes the main peak to be associated with a satellite at higher binding energy, as observed here [27]. The existing satellites confirm the existence of copper as Cu 2+ .…”

“…Two peaks may correspond to two types of oxygen ions. The former can be attributed to the oxygen in the bulk while the latter can be ascribed to the chemisorbed oxygen [27]. Presence of an oxygen rich surface layer has been reported by Prakash and Varma [24].…”

Multiferroicity: the coupling between magnetic and polarization orders

“…In fact, it was once revealed that the magnitude and sign of the principal super-exchange interaction J in low-dimensional cuprates depend remarkably on the Cu-O-Cu bond angle φ [202,203]. In cuprates with φ ~180º, J has an order of magnitude of 10 2 meV, thus favoring ferromagnetic order.…”