We study the metal-insulator transition in two sets of amorphous Si 1−x Ni x films. The sets were prepared by different, electron-beam-evaporation-based technologies: evaporation of the alloy, and gradient deposition from separate Ni and Si crucibles. The characterization included electron and scanning tunneling microscopy, glow discharge optical emission spectroscopy, energy dispersive X-ray analysis, and Rutherford back scattering. Investigating the logarithmic temperature derivative of the conductivity, w = d ln σ/d ln T , we observe that, for insulating samples, w(T ) shows a minimum, increasing at both low and high T . Both the minimum value of w and the corresponding temperature seem to tend to zero as the transition is approached. The analysis of this feature of w(T, x) leads to the conclusion that the transition in Si 1−x Ni x is very likely discontinuous at zero temperature in agreement with Mott's original views. 71.30.+h,71.23.Cq, Typeset using REVT E X

The field induced maxima in the temperature dependence of the dielectric constants of SrTiO, are shifted down to the temperature range around T = 20 K by hydrostatic pressure.The connection between the temperature T, of the maximum, the inducing field strength E, and the pressure p is nonlinear and corresponds to a relation deduced previously. Die feldinduzierten Maxima in der Temperaturabhangigkeit der Dielektrizitiitskonstanten von SrTiO, werden durch hydrostatischen Druck zu niedrigen Temperaturen im Bereich um T = 20 K verschoben. Die Verknupfung zwischen der Temperatur T, des Maximums, der induzierenden Feldstiirke E und dem Druckp ist nichtlinear und entspricht einer fruher abgeleiteten Beziehung.

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in a recent paper we have shown that the resonance frequency and the elastic compliance s

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