Recent advances in the exploitation of localized surface plasmons (charge density oscillations confined to metallic nanoparticles and nanostructures) in nanoscale optics and photonics, as well as in the construction of sensors and biosensors, are reviewed here. In particular, subsequent to brief surveys of the most-commonly used methods of preparation and arraying of materials with localized surface plasmon resonance (LSPR), and of the optical manifestations of LSPR, attention will be focused on the exploitation of metallic nanostructures as waveguides; as optical transmission, information storage, and nanophotonic devices; as switches; as resonant light scatterers (employed in the different near-field scanning optical microscopies); and finally as sensors and biosensors.

Exploitation of Localized Surface Plasmon Resonance

The aim of this review article on recent developments of mechanochemistry (nowadays established as a part of chemistry) is to provide a comprehensive overview of advances achieved in the field of atomistic processes, phase transformations, simple and multicomponent nanosystems and peculiarities of mechanochemical reactions. Industrial aspects with successful penetration into fields like materials engineering, heterogeneous catalysis and extractive metallurgy are also reviewed. The hallmarks of mechanochemistry include influencing reactivity of solids by the presence of solid-state defects, interphases and relaxation phenomena, enabling processes to take place under non-equilibrium conditions, creating a well-crystallized core of nanoparticles with disordered near-surface shell regions and performing simple dry time-convenient one-step syntheses. Underlying these hallmarks are technological consequences like preparing new nanomaterials with the desired properties or producing these materials in a reproducible way with high yield and under simple and easy operating conditions. The last but not least hallmark is enabling work under environmentally friendly and essentially waste-free conditions (822 references).

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Hallmarks of mechanochemistry: From nanoparticles to technology

Hydrothermal technology for nanotechnology

The system H2O–NaCl. Part I: Correlation formulae for phase relations in temperature–pressure–composition space from 0 to 1000 °C, 0 to 5000 bar, and 0 to 1 XNaCl

The hydrothermal technique provides an excellent possibility for processing of advanced materials whether it is bulk single crystals, or fine particles, or nanoparticles. The advantages of hydrothermal technology have been discussed in comparison with the conventional methods of materials processing. The current trends in hydrothermal materials processing has been described in relation to the concept of soft solution processing, as a single-step low energy consuming fabrication technique. Also some recent developments in multi-energy processing of materials such as microwave-hydrothermal, mechanochemical-hydrothermal, electrochemical-hydrothermal, sonar-hydrothermal, etc. have been discussed. An overview of the past, present and future perspective of hydrothermal technology as a tool to fabricate advanced materials has been given with appropriate examples.

Hydrothermal processing of materials: past, present and future

Reaction mechanisms for the hydrothermal synthesis of barium titanate are evaluated. Feedstocks of barium hydroxide octahydrate and anatase titania are reacted for varying durations (1–72 h) to provide intermediate-stage samples for characterization by transmission electron microscopy/ energy-dispersive spectroscopy (TEM/EDS), X-ray diffractometry (XRD), and inductively coupled plasma spectroscopy (ICP). Quantitative evaluation of the extent of reaction by ICP and XRD methods permits the analysis of data with the Johnson-Mehl-Avrami equation. This analysis reveals two reaction-rate regimes. Kinetic analysis, based on reaction progress, yields insight into the first reaction-rate regime but is inconclusive in the analysis of the second reaction-rate regime. In the first regime, at the early stage of barium titanate formation, a dissolution-precipitation mechanism dominates. In contrast, in the second regime, at longer reaction times, an in-situ transformation mechanism is probably dominant. However, multiple reaction mechanisms (e.g., in-situ transformation and dissolution-precipitation) may be competing for rate control. Alternatively, dissolution-precipitation may be the dominant mechanism throughout the barium titanate synthesis, with nucleation and growth controlling the first regime and dissolution rate controlling the second regime.

Kinetics and Mechanisms of Hydrothermal Synthesis of Barium Titanate

A thermodynamic method is proposed for analyzing the hydrothermal synthesis of ceramic materials. The method utilizes standard-state thermodynamic data for solid and aqueous species and a compressive activity coefficients model to represent solution nonideality. The method is used to generate phase stability diagrams for the species that predominate in the system. The stability diagrams can be used to predict the optimum suspension synthesis conditions (i.e., feedstock composition, pH and temperature) for hydrothermal synthesis of ceramic materials. The synthesis of barium titanate and lead titanate are discussed as examples.

Thermodynamic modeling of hydrothermal synthesis of ceramic powders

In broad terms, hydrothermal synthesis is a technology for crystallizing materials (chemical compounds) directly from aqueous solution by adept control of thermodynamic variables (temperature, pressure and composition). The objective of this chapter is to introduce the field of hydrothermal materials synthesis and slow how understanding solution thermodynamics of the aqueous medium can be used for engineering hydrothermal crystallization processes. In the first section, we will focus on hydrothermal synthesis as a materials synthesis technology by providing history, process definitions, technological merits and comments on its current implementation in industry. In the second section, we will describe how thermodynamic modeling is being developed as an engineering tool to predict equilibrium phase assemblages and use this predictive power as an engineering tool for development of hydrothermal technology for materials synthesis.

Hydrothermal crystallization of ceramics

A thermodynamic model for hydrothermal synthesis of alkaline-earth titanates has been utilized to predict the optimum conditions for the synthesis of phase-pure CaTiO3. The predictions have been experimentally validated using Ca(N03)2 or Ca(OH)2 as sources of calcium and crystalline or hydrous T i 0 2 as a source of titanium at moderate temperatures (433-473 K). Practical experimental techniques have been developed to avoid the contamination of the calcium titanate with undesirable solid phases (e.g., calcium carbonate or hydroxide). These conditions were compared with those previously determined for the Ba-Ti and Sr-Ti hydrothermal systems.

Thermodynamics of the Hydrothermal Synthesis of Calcium Titanate with Reference to Other Alkaline-Earth Titanates

A comprehensive model for calculating the electrical conductivity of multicomponent aqueous systems has been developed. In the infinite-dilution limit, the temperature dependence of ionic conductivities is calculated on the basis of the concept of structure-breaking and structure-making ions. At finite concentrations, the concentration dependence of conductivity is calculated from the dielectric continuum-based mean-spherical-approximation (MSA) theory for the unrestricted primitive model. The MSA theory has been extended to concentrated solutions by using effective ionic radii. A mixing rule has been developed to predict the conductivity of multicomponent systems from those of constituent binary cation−anion subsystems. The effects of complexation are taken into account through a comprehensive speciation model coupled with a technique for predicting the limiting conductivities of complex species from those of simple ions. The model reproduces the conductivity of aqueous systems ranging from dilute to con...

Malgorzata M. Lencka

Papers

Kinetics and Mechanisms of Hydrothermal Synthesis of Barium Titanate

Thermodynamic modeling of hydrothermal synthesis of ceramic powders

Hydrothermal crystallization of ceramics

Thermodynamics of the Hydrothermal Synthesis of Calcium Titanate with Reference to Other Alkaline-Earth Titanates

Computation of Electrical Conductivity of Multicomponent Aqueous Systems in Wide Concentration and Temperature Ranges