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The lignocellulosic biomass recalcitrance is the uppermost factor for the utilization of this renewable resource. The development of new pre-treatments, addressed to enhance performance in lignocellulosic biomass conversion into biofuels, fine chemicals, and as potential sources of building blocks for materials, must be focus in two main areas: effectiveness (cost-effective and chemical effective) and green chemistry. In this research, a set of different biomass sources (farmer, harvested wild trees and secondary products) were studied to evaluate the high efficiency of the non-liquid nitrogen (LN) and LN-treated biomass samples’ planetary ball milling performance. The samples have been characterized by particle size distribution, thermogravimetric, FT-IR, statistical chemometric and chemical oxidation analysis. The results have shown a high level on the rupture of the crystallinity and depolymerization degrees of the cellulose and the lignin, for both, non-LN and LN-treated samples. The thermogravimetric analysis showed a clear diminishing in temperature degradation, and a larger amount of biomass degraded at lower temperature, as well as, a high chemical oxidation degree than not milled samples. Finally, the LN-treated samples even exhibited a lower degradation temperature, a larger amount of biomass degraded at lower temperature and a higher oxidation degree, than those non-LN milled.

The ignition time (tig) of the mechanically induced self-sustaining reaction (MSR) process involving the formation of TiB2 from Ti/2B elemental mixtures was used to study the influence of the ratio (k = -ωv/ωd) between the rotational speed of the supporting disc (ωd) and vials (ωv) on the milling efficiency of a Pulverisette 4 planetary mill. The variation of the inverse of the ignition time (1/tig), which is directly related to the milling power provided by the planetary mill, with the process conditions has shown that it is not possible to find a single k value as optimal independently of the experimental conditions used (ωd and the ball-to-powder ratio, BPR). Moreover, it was observed that the lowest milling efficiency (longer tig values) was found for k = 1, which is the usual value employed in routine laboratory works. The best efficiencies were found for the larger k values (2.5 or 3). At lower ωd, the shortest tig was obtained for k = 2.5 and at higher ωd for k = 3, independently of BPR.

In the present manuscript the authors have systematically investigated the composition and microstructure of a series of ternary nitrides (Ti xV1-xNy) (0.0 ≤ x ≤ 1.0) prepared by mechanosynthesis, using XRD, SEM, EELS, XAS and TGA. The ternary titanium-vanadium nitride (TixV1-xNy) has been obtained in all range of compositions by the mechanical treatment of the two metals under nitrogen pressure in a planetary mill with a maximum milling time of 3 h and without any post-heating treatment. The materials' microhardnesses were measured after sinterisation and compared to those reported in the literature for these types of materials. When compared with the previously reported data for bulk samples, these values are similar or higher for compositions within the range x = 0.5 to x = 0.77 (TixV 1-xN)

Vanadium carbonitrides (VCxN1−x) were prepared via mechanosynthesis from mixtures of elemental vanadium and carbon with different V/C atomic ratios under a nitrogen atmosphere using a high-energy ball mill. We obtained the full composition range of carbonitrides at room temperature. The products were characterized using X-ray diffraction, scanning electron microscopy and electron energy loss spectroscopy. The results showed particle-sized products with high sinterability and very high microhardness.

Nanocrystalline Sb2S3 particles have been synthesized from Sb and S powders by high-energy milling in a planetary mill using argon protective atmosphere. X-ray diraction, particle size analysis, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, electron diraction, high resolution transmission electron microscopy, UV-VIS, and dierential scanning calorimetry methods for characterization of the prepared particles were applied. The powder X-ray diraction pattern shows that Sb2S3 nanocrystals belong to the orthorhombic phase with calculated crystallite size of about 36 nm. The nanocrystalline Sb2S3 particles are constituted by randomly distributed crystalline nanodomains (20 nm) and then these particles are forming aggregates. The monomodal distribution of Sb2S3 particles with the average hydrodynamic parameter 210 nm was obtained. The quantication of energy dispersive X-ray spectroscopy analysis peaks give an atomic ratio of 2:3 for Sb:S. The optical band gap determined from the absorption spectrum is 4.9 eV, indicating a considerable blue shift relative to the bulk Sb2S3. Dierential scanning calorimetry curves exhibit a broad exothermic peak between 200 and 300 C, suggesting recovery processes. This interpretation is supported by X-ray diraction measurements that indicate a 23-fold increase of the crystallite size to about 827 nm as a consequence of application of high temperature process. The controlled mechanochemical synthesis of Sb2S3 nanoparticles at ambient temperature and atmospheric pressure remains a great challenge.

The formation of ZnSe via a mechanically-induced self-sustaining reaction (MSR) from a Zn/Se mixture showed that only size reduction and mixing of the reactants without product formation occurred during the induction period prior to ignition. Therefore, all mechanical energy supplied by the planetary mill during this time, called the ignition time (t ig), was used exclusively in the activation of the reactants. This system was chosen to study the dependence of t ig on the main parameters characterising the milling intensity of planetary mills. The variation of the ignition time with the process conditions reflected changes in the mechanical dose rate of the planetary mill. A direct relationship between the inverse of the ignition time and the power of the planetary mill was established, which allows the validation of theoretical models proposed in the literature for the energy transfer in milling devices and the comparison of milling equipment efficiencies

The high-temperature mechanical properties of the mixed ionic-electronic conductor perovskite BaCe0.95Y0.05O3-δ with average grain size of 0.40μm have been studied in compression between 1100 and 1300°C in air at different initial strain rates. The true stress-true strain curves display an initial stress drop, followed by an extended steady-state stage. As the temperature decreases and/or the strain rate increases, there is a transition to a damage-tolerant strain-softening stage and eventually to catastrophic failure. Analysis of mechanical and microstructural data revealed that grain boundary sliding is the primary deformation mechanism. The strength drop has been correlated with the growth of ultrafine grains during deformation, already present at grain boundaries and triple grain junctions in the as-fabricated material.

The pathway for vanadium nitride VN formation obtained by milling treatment has been traced out. At the initial stages of the process, the reactant, vanadium metal, showing body-centered cubic bcc structure, becomes highly distorted. Simultaneously, the formation of a small nucleus of the product, VN, takes place. X-ray absorption spectroscopy XAS has allowed the quantification of the distortion degree as well as the detection of the VN nucleus in the early stages of their formation, while other standard structural characterization techniques are unable to detect such phenomena. For increasing milling times, apart from the expected increase in the size of the VN nucleus, a polymorphic transformation from bcc to fcc vanadium metal has been recorded. This phase might play a key role in the overall synthesis process and could be a reaction intermediate in other solid state processes involving V metal. The sensitivity of XAS to noncrystalline domains and to highly distorted environments, as well as the use of high resolution x-ray diffraction, has provided the relevant information to understand the whole reaction process.

High temperature protonic conductors (HTPC) were fabricated by solid-state sintering and by melt processing by laser-heated floating zone method. Several families of compositions were selected: SrCe1-xMxO3- (with M: Zr and Y; x = 0.1, 0.2), BaCe1-xMxO3- (with Yb, Ca and Y; x = 0.05, 0.2), Sr3Ca1.18Nb1.82O9-, SrZr0.8Y0.2O3- and SrTi0.95Sc0.05O3-. Their mechanical properties have been studied by compression test at constant load and constant compression rate.As produced directionally solidified materials presented a unique microstructure consisting of strongly textured cells with an intercellular phase. The cells have a crystalline Pnma structure. The relation between the processing, dopants, microstructure and mechanical properties is discussed. Understanding of plasticity is important to determine the ultimate component performance, and because its direct relationship to processing and transport. The high temperature mechanical properties of melt grown crystals are superior to the mechanical properties of polycrystals.

El estudio de la influencia ejercida por la energía mecánica en la reactividad química de sólidos tiene ya más de un siglo de historia. Probablemente la primera observación experimental de un cambio en la reactividad, causada por la introducción de defectos en sólidos cristalinos, fue la realizada por Faraday quien observó que ciertas sales hidratadas se deshidrataban espontáneamente cuando se arañaban con un alfiler. No obstante, el primer trabajo sistemático dirigido a poner de manifiesto que la energía mecánica es tan efectiva como las energías térmicas, eléctrica o lumínica se debe, sin duda, a Carey-Lea. Este autor mostró que la fuerza de cizalla es más efectiva que la aplicación de presión hidrostática para inducir transformaciones químicas. Más tarde Parker en 1918 puso de manifiesto la eficacia de dichas fuerzas como inductoras de un gran número de reacciones de doble descomposición entre sales llevadas a cabo en estado sólido. A partir de los trabajos anteriores, el interés en dicha área de investigación ha sido esporádico, según Fox, hasta que durante la segunda Guerra Mundial se comenzó a prestar atención al estudio de las reacciones explosivas inducidas mecánicamente. Desde entonces el estudio de la influencia del tratamiento mecánico de los sólidos tanto en sus propiedades como en su reactividad química ha sufrido un auge tan notable que ha dado lugar a la publicación de diversos artículos de revisión sobre el tema y a que se haya propuesto el nombre de “Mecanoquímica” para designar la parte de la Química del Estado Sólido que se ocupa del estudio de los procesos citados. Lin y Nadiv, han clasificado los procesos mecanoquímicos, según sus aplicaciones, en los grupos que se incluyen a continuación, si bien hay que señalar que dicha clasificación no pretende ser exhaustiva. 1) Cambio de las propiedades fisicoquímicas y generación de otras nuevas. Cambio de la superficie específica y de la energía superficial; alteraciones de la porosidad media y de la dis