Alteration of structural, optical and electrical properties of CdSe incorporated polyvinyl pyrrolidone nanocomposite for memory devices

The important enhancement in the structural, dielectric and optical properties of pure polymer and CdSe incorporated polyvinyl pyrrolidone has been reported in this paper. The surface morphology of CdSe/PVP nanocomposite film is studied by using scanning electron microscopy (SEM). The chemical composition of different elements has been reported using energy dispersive X-ray (EDX) spectrum. The structure of polymer nanocomposite is determined with the help of X-ray diffraction (XRD) spectrum and is observed to be hexagonal. Particle size, intercrystalline separation, interplanner spacing, lattice parameters, strain and dislocation factors are calculated using XRD results. Fourier transform infrared spectroscopy (FTIR) and Photoluminescence (PL) analysis have been studied in order to check the possible interaction between CdSe quantum dots and polyvinyl pyrrolidone (PVP) matrix. The ac conductivity of CdSe/PVP nanocomposite is found to be higher as compared to pure polymers. The highest value of conductivity observed at 60203 Hz and at 523 K is found to be [Formula: see text][Formula: see text]Sm[Formula: see text]. Comparative study of dielectric constant, dielectric losses, dissipation factor, electric modulus and impedance has been performed. The semi-circles in impedance measurement for both materials show the bulk electrical properties that result in single relaxation process in CdSe/PVP nanocomposite.

Development of a 1MV-Field-Emission Electron Microscope II. Performance

The development of increasingly coherent and penetrating electron beams in electron microscopy will hasten progress in such fields as high resolution imaging, electron holography, and material structure investigation. Now that we have completed the development of the 1MV-FE- TEM (H-1000FT), we report its performance from the viewpoint of coherent illumination.We observed thin films of gold in testing the high-resolution performance of H-1000FT.Crystal lattice fringes are formed from the interference between Bragg diffracted electron waves. In TEM observation of the films, the visibility of the fringes depends on the coherence of the electron wave and the overall stability of the microscope. Here, we calculated chromatic aberration-limited resolution d, given by ∼-(Δ ƛ)1/2, to be ∼ 0.6 Å (Δ:focus spread). We then slightly tilted the illumination to partially escape from the chromatic effect and to enable us to a shorter spacing lattice image. Figure 1 shows a lattice fringe image we obtained for a Au thin film, in which lattice fringes of 0.498 Å are clearly visible.

Development of A 350-KV Holography Electron Microscope and its Applications

The 350 kV field-emission electron microscope shown in Fig.1 has been developed to widen the applications of electron holography. A field emission beam is used because it is very bright at first and monochromatic. However, its brightness deteriorates while passing through accelerating electrodes and condenser lenses because of their spherical and chromatic aberrations. A magnetic lens is installed just below a (310)-oriented tungsten tip. A magnetic lens is used so that the electron source image can be located at the most favorable position between the accelerating tube and the first condenser lens to minimize the aberrations and to increase brightness. The measured brightness (probe current) ranges from 1.4x109 A/cm2/sr (0.37 nA) to 6.7x108 A/cm2/sr (2.2 nA) with 10 μA total emission current at 300 kV.These increased brightness and narrow energy spread of the electron beam enable observing fine spacing lattice fringes in a gold thin film. Lattice fringes of 0.065 nm spacing were actually observed in the electron micrograph shown in Fig. 2. The incident electron beam was along the [001] axis, and the (400) and reflected beams were used to form the fringes. A 0.055 nm spacing lattice image is shown in Fig. 3. These fringes resulted from the interference of the electron beam, with an incident axis from the [111] direction into the gold thin film, by the and diffracted beams. This spacing is the shortest observed to date.