Band-gap energies of sol-gel-derived SrTiO3 thin films were studied in terms of annealing temperature and film thickness. The band-gap energies of highly crystallized films were comparable to those of single crystals reported, whereas for poor-crystallized films, their band-gap energy values were much larger than those of single crystals. The larger band-gap energy shift was believed to be mainly due to both quantum size effect and existence of amorphous phase in thin films. The band-gap energies also showed a strong dependence on film thickness. There was a critical film thickness (∼200 nm), above which the films had band-gap energies close to those of crystals or bulks, but below that, the values shifted largely, which can be attributed to the influence of crystallinity of thin films. Such a thickness effect of band-gap energy should be of high interest in optical device applications.

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The oxygen sensing properties of SrTiO 3 -based thin films have been investigated at room temperature. First, nondoped SrTiO 3 was investigated. Although such a material is highly sensitive, its electrical resistance was too high and not feasible for practical use. Donor (Nb 5þ ) could lower the resistance of SrTiO 3 ; however, the sensitivity was lost. UV-light irradiation or t 2 -type acceptor (Cr 3þ ) doping could lower the resistance and yet maintain the sensitivity. In contrast to t 2 -type acceptor doping, e-type acceptor (Fe 3þ ) doping could lower the resistance; however, the sensitivity was lost. In this paper, we discuss the phenomena from the viewpoint of polaron-controlled carrier conduction.

Homogeneous LaNiO3 thin films were grown on thermally oxidized silicon (SiO2/Si) substrates by a sol-gel technique, for the subsequent sol-gel deposition of (Pb, La)TiO3 thin films, under the assumption that the structural and compositional compatibility between ferroelectric films and bottom electrodes could lead to enhanced electrical properties of ferroelectric thin films. In this work, the LaNiO3 films served three functions: the first was used as bottom electrodes for the fabrication of integrated ferroelectric devices on Si due to their low resistivity; the second was used as a seeding layer, promoting perovskite phase formation due to their structural compatibility with ferroelectric films; and the third was to suppress the composition diffusion between ferroelectric films and bottom electrodes due to their composition compatibility. The experimental results demonstrated that (Pb, La)TiO3 films prepared on the LaNiO3/SiO2/Si substrates had excellent electrical properties. The dielectric constant and dielectric loss were 1468 and 0.033, respectively. The dielectric constant is rather high among the values reported for (Pb, La)TiO3 thin films. The remanent polarization and coercive field were 4.24 μC/cm2 and 23.2 kV/cm, respectively.

We present a novel approach to the solid-state synthesis of garnet-type cubic Li7La3Zr2O12 (c-LLZO) nanostructured particles with 1.0 mass% Al at 750 o C within 3 h. In contrast to conventional solid-state processes, a highly reactive precursor was prepared in two steps: (i) by homogenizing the stoichiometric mixture without Li, and (ii) subsequent addition of Li in the form of an ethanolic solution of lithium acetate. The actual composition determined by ICP analysis was Li6.61La3Zr2Al0.13O11.98. Sintering these nanoparticles at 1100 o C for 3 h in air after cold isostatic pressing brought a dense ceramic pellet with a relative density of 90.5%. The corresponding ionic conductivity with Au electrodes was 1.6 × 10 −4 S cm −1 at room temperature. To study its electrochemical behavior as an electrolyte, a model cell of Li//(1M LiPF6 + c-LLZO)//LiCoO2 configuration was constructed. Cyclic voltammetry of the cell delivered one set of redox couple with narrow voltage separation (15 mV) with a Li + diffusion coefficient at room temperature of about 2 × 10 −11 cm 2 s −1 at the interface between LiCoO2 and 1M LiPF6 + c-LLZO. The cell received an average discharge capacity of 64.4, 60.3, 56.1, 51.9 and 46.9µAh cm −2 µm −1 at discharge rates 0.5C, 1C, 2C, 4C and 6C, respectively. The cell exhibited complete oxidation and reduction reactions with an average initial discharge capacity of about 64 µAh cm −2 µm −1 , which is 92.7 % of LiCoO2 theoretical value.These observations indicate the applicability of the present c-LLZO as an electrolyte for a solid-state Li-ion battery. IntroductionA lithium ion battery (LIB) with higher safety and affordability is of utmost importance for better utilization of renewable energy and high-energy electric vehicles. 1,2 Stringent requirements are highenergy density, long cycle life with improved safety, reliability and leakage-free properties in wider operating temperature regimes, enabling a cost-effective process. In current battery technology, we have relatively promising electrode materials in terms of higher energy density and structural stability. On the other hand, we still use flammable, volatile and unstable organic solvents based electrolytes containing Li-salts with polymer separator in all types of conventional Li-ion batteries. These electrolytes not only cause irreversible capacity losses due to the formation of solid-electrolyte interphases (SEI), but also limit the safety of the batteries. Solidstate electrolytes (SSE) with fast Li-ion diffusion were recognized as promising alternative, addressing better thermal and chemical stabilities and opening a wider operational temperature window. 3 For the high-performance SSE, however, great challenges remain, such as: (i) increase in the ionic conductivity and (ii) optimization of fabrication processes. 4 Within the variety of SSE including lithium superionic conductor (LISICON), thio-LISICON or sodium superionic conductor (NASICON), garnet-type c-LLZO is regarded as one of the most promising SSE due to its high ionic conductivity...

a b s t r a c tBiocompatible hybrid particles composed of hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 , HAp) and ferrite (g-Fe 2 O 3 and Fe 3 O 4 ) were synthesized using a two-step procedure. First, the ferrite particles were synthesized by co-precipitation. Second, the suspension, which was composed of ferrite particles by a co-precipitation method, Ca(NO 3 ) 2 , and H 3 PO 4 aqueous solution with surfactant, was nebulized into mist ultrasonically. Then the mist was pyrolyzed at 1000 1C to synthesize HAp-ferrite hybrid particles. The molar ratio of Fe ion and HAp was (Fe 2 + and Fe 3 + )/HAp ¼6. The synthesized hybrid particle was round and dimpled, and the average diameter of a secondary particle was 740 nm. The cross section of the synthesized hybrid particles revealed two phases: HAp and ferrite. The ferrite was coated with HAp. The synthesized hybrid particles show a saturation magnetization of 11.8 emu/g. The net saturation magnetization of the ferrite component was calculated as 32.5 emu/g. The temperature increase in the AC-magnetic field (370 kHz, 1.77 kA/m) was 9 1C with 3.4 g (the ferrite component was 1.0 g). These results show that synthesized hybrid particles are biocompatible and might be useful for magnetic transport and hyperthermia studies.