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The electrothermodynamic cycle is described by the loop of the electric displacement, D , versus the electric fi eld, E ( D-E loop). In Figure 1 a, a schematic of the theoretical Olsen cycle is presented as ABCD. The cycle begins at a low temperature ( T low ) with no electric fi eld (point A). When the electric fi eld ( E 1 ) is applied, the state moves to point B (path AB), corresponding to the hysteresis loop section of the material obtained at T low (see Figure S1b, Supporting Information), denoting an increase in electric displacement. The temperature is increased to the value T high (path BC). Then, electric displacement corresponds to another hysteresis loop, obtained at T high (point C). Removing the external electric fi eld, the state moves to point D along the hysteresis loop at T high (path CD). Finally, the temperature is decreased to T low , and the state moves to point A (path DA). The produced loop area is considered as an energy density ( N D , the area of the D -E loop); the power density ( P D , = N D f ) is also evaluated from the area. [7][8][9][10][11][12][13][14] To the best of our knowledge, there is no application that satisfi es a true energy breakeven because of the diffi culties associated with fi nding a suitable energy source that can simultaneously give alternative heat and an electric fi eld. [7][8][9][10][11][12][13][14] In this study, a novel electrothermodynamic cycle is presented based on temporal temperature variation to obtain practical net energy from exhaust heat of automobile. Another representative heat electric conversion cycle, the Stirling cycle, is modifi ed, and this cycle has a higher potential than the Olsen cycle. [ 6,7 ] The most representative pyro and piezoelectric material, PZT (C-6, Curie temperature T C : 305 °C), is employed. The temperature variation is considered as a simple pseudo-sinusoidal wave based on the imaging of the temperature fl uctuation of the exhaust gas. An external electric fi eld is applied to the material corresponding to the temperature variation (see details in the Supporting Information). The general Sawyer-Tower (ST) circuit is redesigned by inductions of a Diode and a SWitch (named as DSW circuit, see Figure S2b, Supporting Information) to evaluate the D-E loop and simultaneously harvest the net energy.In Figure 1 a, a schematic of our cycle (ABC 1 D) is shown. The AB path is the same as the Olsen cycle. The material is then isolated and the electric displacement D is kept constant while the temperature is increased to T high . The voltage is increased to the E 2 value (path BC 1 ) based on the electrothermodynamic equation: [ 15,16 ] and p are the electric displacement, electric fi eld, temperature, dielectric permittivity, time, and pyroelectric coeffi cient, respectively (see details in the Supporting Information). Then, the material is reconnected to the circuit, and the state moves to point D (path C 1 D). Finally, temperature is decreased back to T low , and the D-E loop is closed. The triangular area BC 1 C is the additional ...

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Copper nanopowders are prepared by pulsed wire discharge (PWD) using copper wires in nitrogen gas. From experimental results obtained in the present study and published literature, a relationship to predict the particle size of powders prepared by PWD is proposed. A theoretical plasma/vapor density (D th), which is the most important factor for controlling the particle size is defined as m P E c -1, where m, P, and E c are the weight of the wire, pressure of nitrogen gas, and charged energy in the capacitor, respectively. From high-speed photographs obtained during PWD, the relationship between the measured D exp and D th is shown by D exp∝D th 0.6. The relationship between the median particle diameter d 50 and D th is found to be d 50∝D exp∝(D th 0.6)0.4 by transmission electron microscopy observations. This empirical relationship is in agreement with that expected from the formation and growth of particles via Brownian coagulation of free molecules. From the above relationship, it is possible to predict and control the particle size of powders prepared by PWD.

Inert gas condensation (IGC) has been employed to produce nanoparticles of the low-temperature combustion catalyst CuO x /CeO2. For the first time we have used a multiple heating crucible setup to tailor various morphologies over the whole compositional range (2−98% Cu). The factors that control the growth, structure, and morphology of the nanocomposite have been studied. A powerful combination of complementary characterization methods has been used to elucidate the catalytic synergistics of this material. Investigations by high-resolution transmission electron microscopy (HRTEM) and energy-filtered TEM (EFTEM) are supported by X-ray photoelectron spectroscopy (XPS) and high-energy diffraction (HED) measurements. The nonstoichiometric CuO x /CeO2 composite displays an amorphous character consisting of aggregated CeO2 (ceria) nanocrystallites over which amorphous copper clusters (or a thin film of a solid solution) are finely dispersed. In the range 6∼20% Cu, copper is predominantly located at the surface, which can give the material optimum catalytic properties. Development of crust structures, for example, core−shells, are formed in the 30∼70% Cu concentration range and is attributable to a sequential oxidation of Ce followed by Cu and an ideal proportion of lattice expansion for the oxides. We suggest a model that illustrates the formation of the crust structure and may explain the observed extreme dispersion of copper on ceria. The helium gas pressure during the thermalization controls the crystal size and the degree of crystallite aggregation. Rounded particle shapes consisting of epitaxially interfaced nanocrystallites exhibit an X-ray amorphous character, while block-shaped crystals displaying sharp edges and distinct flat surfaces give rise to a higher X-ray crystallinity. Bulk CuO crystals were detected by high-energy diffraction above a 30% Cu content. However, the extreme copper dispersion is preserved even for higher copper contents, showing no limit of surface saturation.

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