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We compute approximations to the electronic states near the gap in a large and realistic model of a-Si. The spatial Ž . structure of the states are computed explicitly and discussed. The properties of the local to extended Anderson transition is described. A qualitative picture of the Anderson transition is described. Implications for conductivity and doping are briefly discussed. q 1998 Elsevi...

Investigations of the system Ba–In–Sn, with the objective to synthesize Ba8In16Sn30 clathrate using Sn and In flux reactions, yielded instead the known BaSn3 compound (P63/mmc; a = 7.228(2) Å, c = 5.469(3) Å) from Sn flux and its In-doped variant BaSn2.8In0.2(1) (a = 7.260(1) Å, c = 5.382(2) Å) from In flux. BaSn3–xInx is the first, and up until now, the only ternary phase containing these elem...

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We introduce the concept that there are two generic classes of Mott insu-lators in nature. They are distinguished by their responses to weak doping. Doped charges form cluster (i.e. distribute inhomogeneously) in type I Mott insulators while distribute homogeneously in type II Mott insulators. We present our opinion on the role inhomogeneity plays in the cuprates.

BiFeO(3) is one of the most studied multiferroic materials. Both its magnetic and ferroelectric properties can be influenced by doping. A large body of work on the doped material has been presented in the past couple of years. In this paper we provide a perspective on general doping concepts and their impact on the material's functionality.

In this article we review Raman studies of defects and dopants in graphene as well as the importance of both for device applications. First a brief overview of Raman spectroscopy of graphene is presented. In the following section we discuss the Raman characterization of three defect types: point defects, edges, and grain boundaries. The next section reviews the dependence of the Raman spectrum ...