Cation-swapped homogeneous nanoparticles in perovskite oxides for high power density

Exsolution has been intensively studied in the fields of energy conversion and storage as a method for the preparation of catalytically active and durable metal nanoparticles. Under typical conditions, however, only a limited number of nanoparticles can be exsolved from the host oxides. Herein, we report the preparation of catalytic nanoparticles by selective exsolution through topotactic ion exchange, where deposited Fe guest cations can be exchanged with Co host cations in PrBaMn1.7Co0.3O5+delta. Interestingly, this phenomenon spontaneously yields the host PrBaMn1.7Fe0.3O5+delta, liberating all the Co cations from the host owing to the favorable incorporation energy of Fe into the lattice of the parent host (Delta E-incorporation = -0.41 eV) and the cation exchange energy (Delta E-exchange = -0.34 eV). Remarkably, the increase in the number of exsolved nanoparticles leads to their improved catalytic activity as a solid oxide fuel cell electrode and in the dry reforming of methane

In situ growth of nanoparticles through control of non-stoichiometry

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Electrochemical Characterization of Ultra-thin Carbon Overcoats for Magnetic Hard Disk Components

Abstract not Available.</jats:p

Electrochemical Impedance Characterization of Ultra-Thin Carbon Overcoats

Ultra-thin carbon overcoats deposited on Al2O3-TiC (AlTiC) substrates were characterized using electrochemical impedance spectroscopy. By depositing diamond-like carbon (DLC) directly on AlTiC, the polarization resistance increased to 10^7 ohm-cm2 from ~10^5 ohm-cm2 for bare AlTiC. Two adhesion layer materials were studied: Si and Si3N4. The polarization resistance of DLC/Si3N4 films was 100 times higher than that of DLC/Si. The impedance, wear and magnetic test results indicated that Si3N4 is a more suitable seed material. Comparing films with the same DLC thickness, the Si3N4 layer thickness showed no influence on the resistance. For the same Si3N4 thickness, a thicker DLC layer yielded slightly higher pore resistance. This study reveals that the thinner carbon overcoats (DLC/Si3N4 thickness = 8/12 or 12/8 Aå) provided equal, if not better, corrosion protection than the thicker films. The advantage of a thinner carbon overcoat is that it facilitates an improvement in sensitivity of the magnetic sensor.</jats:p