The factors limiting the conductivity of fluorine-doped tin dioxide (FTO) produced via atmospheric pressure chemical vapor deposition are investigated. Modeling of the transport properties indicates that the measured Hall effect mobilities are far below the theoretical ionized impurity scattering limit. Significant compensation of donors by acceptors is present with a compensation ratio of 0.5, indicating that for every two donors there is approximately one acceptor. Hybrid density functional theory calculations of defect and impurity formation energies indicate the most probable acceptor-type defects. The fluorine interstitial defect has the lowest formation energy in the degenerate regime of FTO. Fluorine interstitials act as singly charged acceptors at the high Fermi levels corresponding to degenerately n-type films. X-ray photoemission spectroscopy of the fluorine impurities is consistent with the presence of substitutional F O donors and interstitial F i in a roughly 2:1 ratio in agreement with the compensation ratio indicated by the transport modeling. Quantitative analysis through Hall effect, X-ray photoemission spectroscopy, and calibrated secondary ion mass spectrometry further supports the presence of compensating fluorine-related defects.

Superior transparent conducting properties of indium oxide realised by molybdenum donors resonant in the conduction band, avoiding detrimental effects of tin doping.

We have studied the magnetization of vertically aligned graphene nanoflakes irradiated with nitrogen ions of 100 KeV energy and doses in the range 10¹¹–10¹⁷ ions/cm². The non-irradiated graphene nanoflakes show a paramagnetic contribution, which is increased progressively by ion irradiation at low doses up to 10¹⁵/cm². However, further increase on implantation dose reduces the magnetic moment which coincides with the onset of amorphization as verified by both Raman and x-ray photoelectron spectroscopic data. Overall, our results demonstrate the absence of ferromagnetism on either implanted or unimplanted samples from room temperature down to a temperature of 5 K

A new perovskite related Sr 0.97NbO 3 phase has been synthesized. Although both powder X-ray diffraction and selected area electron diffraction studies suggest a primitive cubic perovskite structure with a p #4.023 A ˚, high resolution powder neutron diffraction reveals a subtle lattice distortion from cubic symmetry. The detailed crystal structure has been refined with the orthorhombic space group P2 1 2 1 2 with a=5.6881 A ˚, b=5.6821 A ˚and c=8.0566 A ˚. The structure is built up from two types of NbO 6 octahedra, one elongated, the other compressed along c. The lattice distortion from cubic symmetry has been found to mainly originate from tilting of NbO 6 octahedra, whereas the √2a p ×√2a p ×2a p superstructure arises from ordering of alternate elongated and compressed octahedra.

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Here we study the magnetotransport properties of the ferropnictide crystals BaFe 2 As 2 and BaFe 1.985 Co 0.015 As 2 . These materials exhibit a high field linear magnetoresistance that has been attributed to the quantum linear magnetoresistance model. In this model, the linear magnetoresistance is dependent on the concentration of scattering centers in the material. By using proton-beam irradiation to change the defect scattering density, we find that the dependence of the magnitude of the linear magnetoresistance on scattering quite clearly contravenes this prediction. A number of other scaling trends in the magnetoresistance and high field Hall data are observed and discussed. Proton irradiation has been shown to introduce defects, which are recognized to be predominantly of a point defect character, without significantly altering the electronic structure of the material 16,17 . In contrast, Co doping is expected to modulate both the scattering and carrier concentration. In this paper, we present resistivity, MR and Hall effect measurements on pristine and proton irradiated single crystals of BaFe 2 As 2 and BaFe 1.985 Co 0.015 As 2 and compare our findings with the predictions of the QLM model.The in-plane MR shows unsaturated linear magnetic field dependence in all crystals 2 below the structural and magnetic transitions. The crossover to linear MR behavior occurs at a temperature dependent critical field (B * ) which we find is unaffected by the proton irradiation. A number of other scaling trends in the MR and high field Hall data are observed, which are discussed in light of both the multiband and anisotropic quasiparticle lifetime models.The paper will first introduce the QLM model then describe our experimental efforts to compare systematic changes in the scattering density to the predictions of the QLM model. Finally we will discuss the high field Hall resistance data and observation of scaling relationships.