Effect of lattice volume and strain on the conductivity of BaCeY-oxide ceramic proton conductors

In-situ electrochemical impedance spectroscopy was used to study the effect of lattice volume and strain on the proton conductivity of the yttrium-doped barium cerate proton conductor by applying the hydrostatic pressure up to 1.25 GPa. An increase from 0.62 eV to 0.73 eV in the activation energy of the bulk conductivity was found with increasing pressure during a unit cell volume change of 0.7%, confirming a previously suggested correlation between lattice volume and proton diffusivity in the crystal lattice. One strategy worth trying in the future development of the ceramic proton conductors could be to expand the lattice and potentially lower the activation energy under tensile strain

Second class currents and neutrino mass in mirror transitions

The influence of the second class currents (SCC) on angular correlations, charge asymmetries and electron polarizations in beta decays of mirror nuclei are investigated in the Kubodera-Delorme-Rho (KDR) model. It is shown that these quantities depend in very different ways on the KDR-model parameters ζ and λ, which can be used for their experimental determination. In the middle of the β-spectrum the SCC effects dominate over those due to the neutrino rest mass, but the SCC can not modify the specific tail of the correlation coefficient Aev in the case of a non-zero neutrino mass. More rigorously, we can state that in the case of mv ≠ 0, and independently of the presence of SCC, the correlation coefficient Aev tends to zero (AevGT→0) at the upper end of the β-spectrum. This is contrary to the standard result (which assumes mv = 0), according to which this coefficient tends to a non-zero constant (AevGT = - 1 3βe→- 1 3). © 1989

Second class currents and neutrino mass in mirror transitions

The influence of the second class currents (SCC) on angular correlations, charge asymmetries and electron polarizations in beta decays of mirror nuclei are investigated in the Kubodera-Delorme-Rho (KDR) model. It is shown that these quantities depend in very different ways on the KDR-model parameters ζ and λ, which can be used for their experimental determination. In the middle of the β-spectrum the SCC effects dominate over those due to the neutrino rest mass, but the SCC can not modify the specific tail of the correlation coefficient Aev in the case of a non-zero neutrino mass. More rigorously, we can state that in the case of mv ≠ 0, and independently of the presence of SCC, the correlation coefficient Aev tends to zero (AevGT→0) at the upper end of the β-spectrum. This is contrary to the standard result (which assumes mv = 0), according to which this coefficient tends to a non-zero constant (AevGT = - 1 3βe→- 1 3). © 1989

Polarisation effects of second-class currents in the direct and inverse β decay of nuclei

A general expression for the modulus squared of matrix elements of semileptonic weak processes including the polarisation of the initial (final) nucleus is obtained. The influence of second-class currents (SCC) on various characteristics (the charge asymmetry, the angular and spin correlation coefficients, etc) of the beta decay of 12B, 12N and 6He and of the iso-elastic scattering of nu ( nu ) on 12C is studied. It is shown that experiments with a polarised nucleus will allow new effects, induced by SCC, to be extracted. An optimum geometrical configuration of the test for conducting experiments to observe these effects is found