The dependence of critical temperature on oxygen concentration in YBa2Cu3O6+x in terms of the fragmented chain model

Abstract

Abstract:An extended ASYNNNI model, that beside nearest-neighbour and next-nearest neighbour O-O interactions in the basal plane also includes interactions between the three nearest oxygen atoms, is used to describe the statistics of CuO chain fragmentation and to calculate doping and T in YBa 2 Cu 3 O 6+ . Calculations were made by the Monte Carlo method employing the recently proposed charge transfer model that assumes only chains whose length is equal to, or exceeds, a characteristic (critical) length, , can provide holes to the layers and contribute to doping . The obtained ( ) is then combined with a universal T versus relation to yield T ( ) characteristics that correlate remarkably with those reported in recent experiments. The best coordination between theoretical and experimental T ( ) characteristics has been achieved for = 2, implying that only isolated basal plane oxygen atoms (trivial chains) do not contribute holes to CuO 2 layers. PACS (2008): 74.72.-h, 74.62.-c

Fe3O4 nanoparticles as additives for gamma-ray shielding: Structural and surface characterization

“…Conventional concrete represents a material whose properties are dependent on the constituents of the mixture. Since nanomaterials exhibit advanced properties compared to the bulk materials, nanoparticles are often used to improve the properties of the compact materials [10][11][12][13][14]. The effectiveness of concrete as a gamma radiation shield is significantly improved by the addition of the magnetic nanoparticles additives [15][16][17], since concrete belongs to the group of dielectrics [18].…”