In this review, we summarize the knowledge of the production and properties of charcoal that has been accumulated over the past 38 millenia. The manipulation of pressure, moisture content, and gas flow enables biomass carbonization with fixed-carbon yields that approachor attainthe theoretical limit after reaction times of a few tens of minutes. Much of the heat needed to carbonize the feed is released by vigorous, exothermic secondary reactions that reduce the formation of unwanted tars by augmenting the charcoal yield in a well-designed carbonizer. As a renewable fuel, charcoal has many attractive features:  it contains virtually no sulfur or mercury and is low in nitrogen and ash; it is highly reactive yet easy to store and handle. Carbonized charcoal can be a good adsorbent with a large surface area and a semimetal with an electrical resistivity comparable to that of graphite. Recent advances in knowledge about the production and properties of charcoal presage its expanded use as a renewable fuel, red...

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The Art, Science, and Technology of Charcoal Production†

Oxygen vacancies in transition metal and rare earth oxides: Current state of understanding and remaining challenges

Thermal energy storage: Recent developments and practical aspects

We have recently developed a non-empirical Debye-like model for the inclusion of thermal effects in the equation of state (EOS) of solids. This model allows the calculation of many thermodynamical properties from the E-V relationship. We report the results of a theoretical investigation that explores the EOS of two ionic solids: MgF2 and Al2O3. The interionic interactions are modelized using either the ab initio Perturbed Ion (aiPI) method or the electron gas formalism along with aiPI electronic wavefunctions, which are allowed to relax with crystal strains. Our EOS results are in overall good agreement with experimental data. Other thermodynamic properties behave in the same way, although Gruneisen constant and related quantities have significant errors. This may be caused by numerical inaccuracies on the high order derivatives needed for its calculation.

Thermodynamical properties of solids from microscopic theory : applications to mgf2 and al2o3

A structural phase transition between the cubic (space group, Fm3m) and tetragonal (space group, P42/nmc) phases in a zirconia–ceria solid solution (Zr1−xCexO2) has been observed by Raman spectroscopy. The cubic–tetragonal (c–t″) phase boundary in compositionally homogeneous samples exists at a composition X0 (0.8 < X0 < 0.9) at room temperature, where t″ is defined as a tetragonal phase whose axial ratio c/a equals unity. The axial ratio c/a decreases with an increase of ceria concentration and becomes 1 at a composition X′0 (0.65 < X′0 < 0.7) at room temperature. The sample with a composition between X0 and X′0 is t″ ZrO2. By Raman scattering measurements at high temperatures, the tetragonal (t″) → cubic and cubic → tetragonal phase transitions occur above 400°C in Zr0.2 Ce0.8O2 solid solution.

Raman Scattering Study of Cubic–Tetragonal Phase Transition in Zr1−xCexO2 Solid Solution

The high-temperature structure of zirconia was studied by powder neutron diffraction up to 2400/sup 0/C. The boundaries of the domain of the nonstoichiometric tetragonal form are defined. They are consistent with a tetragonal-cubic transition at 2350/sup 0/C for stoichiometric zirconia. The changes in the structural parameters of the tetragonal form (unit-cell, positional parameters and thermal B factors) with temperature give evidence of medium zirconium and oxygen mobilities. The oxygen ions are, however, always more mobile than the zirconium ions. An enhancement with temperature of the structural anisotropy tends to weaken the weaker of the two distinct Zr-O bonds of the tetragonal zirconia. It results in the transformation into the cubic form which is accompanied by a change in unit-cell volume; this change becomes sharper as the composition tends toward stoichiometry. This transition is probably followed by an increase of the ionic mobility.

Structure and Ionic Mobility of Zirconia at High Temperature

Experimental aspects of the thermochemical conversion of solar energy; Decarbonation of CaCO3

Study of the oxidation of aluminium nitride coatings at high temperature

The high-temperature structure of a–Al2O3 was studied by powder neutron diffraction up to 2000° C. The changes in the structural parameters (unit cell and positional parameters and thermal B factors) with temperature give evidence of low aluminum and oxygen mobilities; Al ions are, however, always more mobile than oxygen. An enhancement with temperature of the structural anisotropy tends to weaken the weaker of the two distinct Al-O bonds. This can be interpreted as an evolution toward the bonding expected in the liquid state.

J.P. Traverse

Papers

Structure and Ionic Mobility of Zirconia at High Temperature

Experimental aspects of the thermochemical conversion of solar energy; Decarbonation of CaCO3

Study of the oxidation of aluminium nitride coatings at high temperature

Neutron Diffraction Study of Structural Characteristics and Ionic Mobility of a-Al2O3 at High Temperatures

Thermochemical conversion of biomass: Gasification by flash pyrolysis study