A single-electron transistor scanning electrometer (SETSE)-a scanned probe microscope capable of mapping static electric fields and charges with 100-nanometer spatial resolution and a charge sensitivity of a small fraction of an electron-has been developed. The active sensing element of the SETSE, a single-electron transistor fabricated at the end of a sharp glass tip, is scanned in close proximity across the sample surface. Images of the surface electric fields of a GaAs/AlxGa1-xAs heterostructure sample show individual photo-ionized charge sites and fluctuations in the dopant and surface-charge distribution on a length scale of 100 nanometers. The SETSE has been used to image and measure depleted regions, local capacitance, band bending, and contact potentials at submicrometer length scales on the surface of this semiconductor sample.

In this manuscript, we investigate the sintering behavior of (K,Na)NbO 3 (KNN)-based ceramics covering unmodified KNN, (K,Na,Li)NbO 3 (KNLN), and KNLN-xBaTiO 3 (KNLN-BT) systems. Three stages of sintering were identified using detailed temperature and time dependent microscopy. The first stage corresponds to rearrangement of random shape particle to form stack of plate type particles. The second stage is characterized by rapid grain growth promoted by formation of liquid phase. The liquid phase was identified to be Na-deficient composition. In the final stage of sintering, densification slows and microstructural coarsening becomes the dominant process. The fraction control of liquid phase was an important factor to obtain dense and uniform microstructure by completely filling the voids between the plate-shaped particle stacks. II. Experimental ProcedureCeramics in the system (K 0.5 Na 0.5 )NbO 3 (0.5KNN), (K 0.5(1Àx) Na 0.5(1Àx) Li x )NbO 3 (xKNLN, e.g. 0.04KNLN 5 (K 0.48 Na 0.48 Li 0.04 )NbO 3 , and 0.05KNLN 5 (K 0.475 Na 0.475 Li 0.05 ) NbO 3 ), and (1Àx)(K 0.48 Na 0.48 Li 0.04 )NbO 3 -xBaTiO 3 [(1Àx) KNLN-xBT] were synthesized from oxides of 499% purity by conventional solid-state route. The powders of K 2 CO 3 , Na 2 CO 3 , Nb 2 O 5 , Li 2 CO 3 , BaCO 3 , and TiO 2 (all obtained from Alfa Aesar, Ward Hill, MA) were mixed for 24 h in a polypropylene jar with zirconia balls. Mixed powders were dried J. Roedel-contributing editor This work was financially supported by Office

To effectively utilize the anisotropic characteristics of hexagonal boron nitride (h-BN), we have developed magnetic h-BN hybrid platelets decorated with iron oxide (Fe 3 O 4 ) nanoparticles, which are used as magnetic carriers for tailoring the anisotropy of h-BN. The as-synthesized Fe 3 O 4 -coated h-BN powders can easily move under a relatively low magnetic field. With the aid of iron oxide nanoparticles, h-BN platelets randomly dispersed in an epoxy matrix are successfully reoriented in a direction vertical to the film plane. Moreover, by utilizing the anisotropic characteristics of h-BN platelets, Fe 3 O 4 -coated h-BN/ epoxy composites exhibit exceptional performance in terms of in-plane thermal conductivity. This result is attributed to an improvement in the heat-transport pathways in composite films due to the anisotropic ordering of thermally conductive h-BN sheets. The Fe 3 O 4 -decorated h-BN platelets will be promising candidates for significantly improving the performances of advanced electronic devices that require excellent thermal conductivity and electrical insulation.

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