Solid solutions Ce 1-x RE x O 2-δ (RE ) Eu, Tb) were prepared by a high-temperature and -pressure method. The products were characterized by X-ray diffraction (XRD), TG, electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), and Mo ¨ssbauer spectroscopy. XRD data analysis showed that all solid solutions crystallized in a singlephase cubic fluorite structure. The nonlinear relationships between the lattice parameter and dopant content for both series of solutions were ascribed to the results of cation substitutions and variations of the relative content of oxygen vacancy Vo ¨and defect associations {RE′ Ce Vo ¨} and {Ce′ Ce Vo ¨}. EPR and XPS measurements confirmed the presence of Ce 3+ ions in the solid solutions. For the solid solutions Ce 1-x Eu x O 2-δ , all Eu ions were determined to be trivalent by XPS and 151 Eu Mo ¨ssbauer measurements. For the solutions Ce 1-x Tb x O 2-δ , all Tb ions were also stabilized in the trivalent state. This result is different from that of the counterpart by hydrothermal conditions, in which a mixed valence of Tb 3+ / Tb 4+ prevails at a higher dopant content. The prepared solutions Ce 1-x Tb x O 2-δ were metastable. With increasing temperature, they would be destabilized and decompose into two fluorite phases, accompanied by partial oxidation from Tb 3+ to Tb 4+ . Alternating current impedance spectroscopy showed primarily bulk conduction for all samples. For the solutions Ce 1-x Eu x O 2-δ , the temperature dependence of the ionic conductivity was linear within the temperature range measured with activation energies of 1.05, 0.82, and 0.87 for x ) 0.2, 0.38, and 0.5, respectively. For the decomposition product of the solid solution Ce 0.71 Tb 0.29 O 2-δ , the conductivity gave two linear regions with smaller activation energies; i.e., the activation energy was 0.60 eV below 600 °C and 0.39 eV above 600 °C. The higher ionic conductivity (1.1 × 10 -2 S/cm at 720 °C) for the decomposition phases of the solution Ce 0.71 Tb 0.29 O 2-δ was ascribed to an electronic component involved in relation to the presence of the mixed valence of Tb 3+ /Tb 4+ and Ce 3+ /Ce 4+ .

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Ballistic electron emission microscopy measurements on individual "end-on" Au Schottky contacts to vertical Si nanowires (NWs) indicate that the local Schottky barrier height at the contact edge is 23 ± 3 meV lower than at the contact center. Finite-element electrostatic simulations suggest that this is due to a larger interface electric field at the contact edge resulting from (equilibrium) positive charge in Si/SiO(2) interface states near the Au/NW contact, induced by local band bending due to the high work function Au film.

The low frequency magnetic field detection ability of magnetoresistive (MR)sensor is seriously affected by 1/f noise. At present, the method to suppress the influence of low frequency noise is mainly to modulate the measured magnetic field by mechanical resonance. In this paper, a novel modulation concept employing a magnetoelectric coupling effect is proposed. A design method of modulation structure based on an equivalent magnetic circuit model (EMCM) and a single domain model of in-plane moment was established. An EMCM was established to examine the relationship between the permeability of flux modulation film (FMF) and modulation efficiency, which was further verified through a finite element simulation model (FESM). Then, the permeability modulated by the voltage of a ferroelectric/ferromagnetic (FE/FM) multiferroic heterostructure was theoretically studied. Combining these studies, the modulation structure and the material were further optimized, and a FeSiBPC/PMN-PT sample was prepared. Experimental results show that the actual magnetic susceptibility modulation ability of FeSiBPC/PMN-PT reached 150 times, and is in good agreement with the theoretical prediction. A theoretical modulation efficiency higher than 73% driven by a voltage of 10 V in FeSiBPC/PMN-PT can be obtained. These studies show a new concept for magnetoelectric coupling application, and establish a new method for magnetic field modulation with a multiferroic heterostructure.

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