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THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

Hierarchical and hollow oxide nanostructures are very promising gas sensor materials due to their high surface area and well-aligned nanoporous structures with a less agglomerated configurations. Various synthetic strategies to prepare such hierarchical and hollow structures for gas sensor applications are reviewed and the principle parameters and mechanisms to enhance the gas sensing characteristics are investigated. The literature data clearly show that hierarchical and hollow nanostructures increase both the gas response and response speed simultaneously and substantially. This can be explained by the rapid and effective gas diffusion toward the entire sensing surfaces via the porous structures. Finally, the impact of highly sensitive and fast responding gas sensors using hierarchical and hollow nanostructures on future research directions is discussed.

Gas sensors using hierarchical and hollow oxide nanostructures: Overview

The structure

CuO nanostructures: Synthesis, characterization, growth mechanisms, fundamental properties, and applications

The electrical response of Ba(Ti 0.90 Zr 0.10 )O 3 (BZT) ceramics obtained by the mixed oxide method as a function of tungsten content was investigated. According to X-ray diffraction analysis the single phase BZT1W (1 wt.% W doped BZT) and BZT2W (2 wt.% W doped BZT) ceramics, crystallized in a perovskite structure, were obtained. It is also shown that tungsten substituted ceramics can be sintered at a reduced temperature when compared to the undoped BZT. Electron paramagnetic resonance (EPR) analyses reveals that substitution of Ti 4+ by W 6+ causes distortion in the crystal structure changing lattice parameter. Substitution of W 6+ on B-site of ABO 3 perovskite BZT ceramics shifted the phase transition to lower temperatures up to a tungsten content of 2 wt.% leading to a relaxor-like behaviour.

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Dielectric response of tungsten modified Ba(Ti0.90Zr0.10)O3 ceramics obtained by mixed oxide method

A polymeric precursor solution was used to deposit pure and Mg doped LiNbO3 thin films on sapphire substrates by spin-coating. The effects of magnesium addition on crystallinity, morphology and optical properties of the annealed films were investigated. X-ray diffraction patterns indicate the oriented growth of the films. Phi-scan diffraction evidenced the epitaxial growth with two in-plane variants. AFM studies show that the films are very homogeneous, dense and present smooth surfaces. The refractive index and optical losses obtained by the prism coupling method were influenced by the magnesium addition.

Influence of Mg on the structural and optical properties of LiNbO3 thin films grown by polymeric precursor method

Thin films of lithium niobate were deposited on the Pt/Ti/SiO/sub 2/ (111) substrates by the polymeric precursor method (Pechini process). Annealing in static air and oxygen atmosphere was performed at 500/spl deg/C for 3 hours. The films obtained were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The dielectric constant, dissipation factor and resistance were measured in frequency region from 10 Hz to 10 MHz. Electrical characterizations of the films pointed to ferroelectricity via hysteresis loop. The influence of oxygen atmosphere on crystallization and properties of LiNbO/sub 3/ thin films is discussed.

Influence of oxygen atmosphere on LiNbO/sub 3/ thin films prepared by Pechini process

Unveiling the metal-insulator transition at YTiO3/LaTiO3 interfaces grown by the soft chemical method

Lead zirconate powder, with Zr/Ti ratio of 50/50 was prepared by polymeric precursor method and doped with 3, 5 and 7 mol% of Sr+2 or Ba, as well as by 0.2 to 5 mol% of Nb+5. The powder was calcined at 750°C by 4 hours and milled during 1.5 h in isopropilic alcohol. Powders were characterized by surface area measurements (BET method), by infrared spectroscopy and by X-ray diffraction to characterize the crystal structure. Isostatically pressed samples were sintered in a dilatometer furnace by using a constant heating rate of 10 °C/min from ambient to 1200°C. Synthetic air and air with water vapor were used as atmospheres. Both Sr+2 and Ba+2 substitute Pb+2 and favor the formation of rhombohedral phase. Otherwise, Nb+5 substitute preferentially Zr+4 favoring tetragonal phase. The concentration of dopants and the atmosphere influence the densification and the microstructure of the PZT, which alters the dielectric and piezoelectric properties of the ceramics.

Alexandre Zirpoli Simões

Papers

Dielectric response of tungsten modified Ba(Ti0.90Zr0.10)O3 ceramics obtained by mixed oxide method

Influence of Mg on the structural and optical properties of LiNbO3 thin films grown by polymeric precursor method

Influence of oxygen atmosphere on LiNbO/sub 3/ thin films prepared by Pechini process

Unveiling the metal-insulator transition at YTiO3/LaTiO3 interfaces grown by the soft chemical method

Synthesis and Sintering Of PZT Ceramics