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The cyclic voltammetric behavior of [normalAuCl4]− on glassy carbon (GC) and gold electrodes in room-temperature ionic liquids, i.e., 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4) and 1- n -butyl-3-methylimidazolium tetrafluoroborate (BMIBF4) has been examined. A series of two-electron (2e-) and one-electron (1e-) reductions of the [AunormalCl4]−–[AunormalCl2]−–Au redox system could be observed at GC electrode. For example, the cathodic and anodic peaks corresponding to the [AunormalCl4]−∕[AunormalCl2]− redox couple were observed at ca. 0.2 and 1.2V vs a Ag wire quasi-reference electrode, respectively, in EMIBF4 , while those observed at −0.5 and 0.5V were found to correspond to the [AunormalCl2]−∕Au redox couple. The disproportionation reaction of the 2e-reduction product of [normalAuCl4]− , i.e., [normalAuCl2]− to [normalAuCl4]− and Au metal, was also found to occur significantly. A single reduction peak corresponding to the three-electron (3e-) reduction of [normalAuCl4]− to Au metal was observed at Au electrode. The electrodeposition of Au nanoparticles was carried out on GC electrode in these ionic liquids containing [normalAuCl4]− by applying potential-step electrolysis in a different potential range, i.e., the potential was stepped from 0.4V to 0 and −1.0V , at which the reduction of [normalAuCl4]− to [normalAuCl2]− and Au, respectively, takes place. The results obtained demonstrate that the electrodeposition of gold may occur via a disproportionation reaction of [normalAuCl4]− to [normalAuCl2]− and Au as well as via a series of the reductions of [normalAuCl4]− to [normalAuCl2]− and further, [normalAuCl2]− to Au. The size and morphology of the prepared Au nanoparticles as well as the relative ratio of the Au(111), Au(110), and Au(100) crystalline orientation domains constituting the polycrystalline Au nanoparticles electrodeposited were found to largely depend on the stepped potential (i.e., 0 and −1.0V ). Interestingly, the Au nanoparticles prepared by a potential-step electrolysis from 0.4to0V are enriched in the Au(110) single-crystalline domain.

Polycrystalline samples of strontium series perovskite‐type oxides, SrCeO3 and SrZrO3, were prepared and the thermophysical properties were measured. The chemical compositions of the samples do not deviate from the stoichiometric composition. The oxygen‐to‐metal (O/M) ratios of SrCeO3 and SrZrO3 are 3.00±0.03 and 2.98±0.01, respectively. The average linear thermal expansion coefficients are 1.11 × 10−5 K−1 for SrCeO3 and 9.69 × 10−6 K−1 for SrZrO3 in the temperature range between 300 and 1000 K. The melting temperatures Tm of SrCeO3 and SrZrO3 are 2266 and 2883 K, respectively. The longitudinal and shear sound velocities were measured by an ultrasonic pulse–echo method at room temperature in air, which enables to evaluate the elastic moduli and Debye temperature. The heat capacity was measured by using a differential scanning calorimeter in high‐purity argon atmosphere. The thermal diffusivity was measured by a laser flash method in vacuum. The thermal conductivities of SrCeO3 and SrZrO3 at room temperature are 2.95 and 4.06 W·m−1·K−1, respectively.

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In-site gold electro-deposition and electro-dissolution have been examined using polycrystalline gold-coated quartz crystal electrode in a room-temperature ionic liquid of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4). In EMIBF4 media containing 1-ethyl-3-methylimidazolium chloride, the species of AuI (probably [AuICl2]−) resulting from the electrochemical oxidation of the Au surface was very stable and a reversible voltammetric response of the AuI/Au0 couple was observed at 0.25 V vs. Ag wire quasi-reference electrode (Ag(QRE)). In situ electrochemical quartz crystal microbalance (EQCM) technique combined with cyclic voltammetry, double potential-step chronoamperometry and double potential-step chronocoulometry has been successfully applied to investigate the cathodic deposition of AuI ion to Au metal and the anodic dissolution of Au from the Au electrode surface. It was found that the frequency change of quartz crystal electrode during the electrolysis can be interpreted in terms of rigid mass changes based on the Sauerbrey equation. The EQCM analysis of the electro-dissolution and electro-deposition of Au in the potential range of −0.60 to 0.50 V vs. Ag(QRE) gave the molecular mass equivalent of Au (197 g mol−1) corresponding to a one-electron reduction and oxidation of the AuI/Au0 redox couple.