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A new study investigates the local order and magnetic behavior of thin epitaxial films of gallium or scandium-doped and undoped yttrium iron garnet produced by swift heavy ion irradiations.

A study was conducted on the ac/dc transport and dielectric properties of GeV heavy ion-irradiated single crystals of barium hexaferrite and yttrium iron garnet. Results show that the dielectric relaxation less than 100 kHz corresponds to the blocking metal/insulator contact space-charge polarization. Phonon mode freezing was found to create polaron hopping conduction resulting in non-Arrhenius characteristics.

A study of the damage production in yttria-stabilized cubic zirconia single crystals irradiated with swift heavy ions is presented. The damage results from the formation of tracks due to the huge electronic excitations induced in the wake of incident ions might be usd to predict the damage evolution in other nonamorphizable ceramics irradiated with swift heavy ions.

There is a need for a conceptual and analytical model to describe and interpret the common shrinkage curves of structured soil samples. In this work, we propose a new device for direct shrinkage measurement of unconfined structured soil samples and discuss the relevance of parametric models of the shrinkage curve to fit the experimental data. The experimental procedure consists of simultaneous and continuous measurements of the diameter, height, and weight of an initially saturated soil sample as it dries. The shrinkage measurement can be completed for the full moisture range in a short time (2-3 d), and all shrinkage phases can be established easily and accurately identified. The points of transition between the different shrinkage zones of the shrinkage curve are considered as characteristics of the shrinkage process. They are used as parameters to model the experimental shrinkage curves by linear shrinkage zones separated by curvilinear transition ones. The efficiency of two parametric models to fit the experimental data and to provide the characteristic points of the curve are compared and discussed. A new procedure for fitting the shrinkage curves of structured soil samples and for determining the best position of the characteristic points on the curves is proposed.

Abstract: Single crystals of gadolinium gallium garnet, Gd3Ga5O12 have been irradiated with various swift heavy ions (32S, 52Cr, 63Cu, 86Kr, 128Te, 129Xe, 181Ta, 208Pb, 238U) in the electronic stopping power regime. The extent of the induced damage is extracted from channelling Rutherford backscattering experiments and the corresponding track radii are deduced. At low beam energy (around 1.5MeV/u), the electronic stopping power threshold of damage creation is 7.2±1.2keV/nm while it is 9.3±0.9keV/nm for beam energy around 6MeV/u. The inelastic Thermal Spike model (i-TS) is used in order to calculate the track radii versus (dE/dx)e using λ, the mean diffusion length of the energy deposited on the electrons, as the only fitting parameter model. The i-TS model was extended to some other amorphizable materials like YBa2Cu3O7−δ , GeS and LiNbO3. The results, combined with previous ones extracted from BaFe12O19, Y3Fe5O12, Y3Al5O12 and α-SiO2 quartz data, showed that λ decreases when the band gap energy E g increases. By extrapolation and depending of the material, the damage threshold induced by electronic excitation can appear at beam energy as low as 10−3 to 10−1 MeV/u. [Copyright &y& Elsevier]