Polaronic Conduction in La2−Sr CoO4(0.25≤x≤1.10) below Room Temperature

Giant dielectric response and mixed-valent structure in the layered-ordered double-perovskite ceramics

“…The bulk conductivity should be given firstly if investigation of the conductive mechanism of La 2 CuSnO 6 ceramics is needed. As shown in the work of Iguchi et al [20], the impedance spectrum is used to determine the contribution from the grain interiors, grain boundaries and interface of sample-electrode, and the response frequency decreases in the turn. The typical impedance spectra at various temperatures are shown in Fig.…”

Magnetic and transport properties of the layered perovskite systemSr2−yYyCoO4Wang1, Takayama‐Muromachi2 2005Phys. Rev. B8712811View full textAdd to dashboardCite

“…[10][11][12] It is well known that the dimensionality of a system is a key factor governing its electronic structure, and thus, twodimensional ͑2D͒ layered cobalt oxides are quite interesting to compare with the three-dimensional ͑3D͒ perovskites. Thus far, various studies have been carried out on K 2 NiF 4 -type cobalt oxides, [13][14][15][16][17][18][19][20] 4 according to their theoretical studies using the unrestricted Hartree-Fock approximation and the real-space recursion method. 19,20 In the present study, we have developed a K 2 NiF 4 -type cobalt oxide with only Co 4+ ions, Sr 2 CoO 4 , using a high pressure and high temperature technique.…”

Giant dielectric constant in Nd2NiO4+δ ceramics obtained by spark plasma sintering

“…The activation energy of bulk resistivities is just a bit larger than that of dielectric relaxation, while that of grain boundary is smaller. In the polaronic scenario [22], the activation energy required for electrical conduction due to a hopping process of small polarons is the sum of the hopping energy, which is equal to that of the dielectric relation, and half of the potential difference between a free polaron and a polaron bound to a trap. So the activation energy of electrical conduction should be larger than that of dielectric relaxation.…”