Composition-induced structural phase transitions in the (Ba1xLax)2In2O5+x (0pxp0.6) system

Composition-induced structural phase changes across the high temperature, fast oxide ion conducting (Ba1xLax)2In2O5+x, 0pxp0.6, system have been carefully analysed using hard mode infrared (IR) powder absorption spectroscopy, X-ray powder diffraction and electron diffraction. An orthorhombic brownmillerite to three-dimensionally disordered cubic perovskite phase transition in this system is signalled by a drastic change in slope of both wavenumber and average line widths of IR spectra as a function of composition. Some evidence is found for the existence of an intermediate tetragonal phase (previously reported to exist from electron diffraction data) around x 0:2: The new spectroscopic data have been used to compare microscopic and macroscopic strain parameters arising from variation in composition. The strain and spectroscopic data are consistent with firstorder character for the tetragonal-orthorhombic transition, while the cubic-tetragonal transition could be continuous. Differences between the variation with composition of spectral parameters and of macroscopic strain parameters are consistent with a substantial order/disorder component for the transitions. There is also evidence for precursor effects within the cubic structure before symmetry is broken

Sustainable management: a strategic challenge for a global minerals and metals industry

This paper refers to the concept of sustainable management as the management approach which efficiently integrates economic, environmental and social issues into the operations of the minerals and metals industries, with the aim of creating long-term benefits for all stakeholders, and securing the support, cooperation, and trust of the local community. Among many other issues, sustainable management deals with strategy, responsible project feasibility decisions, managing for operational efficiency, improved risk management, enhanced stakeholder relationships, and corporate reputation. Overall, it deals with seeking long-term competitive advantages through responsible management of environmental and social issues. An essential requirement for sustainable management is the corporate commitment to the values of sustainability, but this is not sufficient. Also essential is the development of a business culture where sustainability is a high professional and business value. Furthermore, an organizational structure with specific roles and integration mechanisms and adequate management systems are also required. Regarding business culture, a well-established business code is a necessary but an insufficient condition. Sustainable management relies on individual ethical conduct and trust to foster full participation of stakeholders and to encourage commitment among them. It allows decision making at appropriate levels in the organization and encourages individual risk-taking for continuous improvement. Without trust, social licence is not achievable. In this paper, the concept of sustainable management is introduced as the management approach that integrates a business culture, strong leadership and an organizational structure that strives for long term economics benefits through sustainability. To achieve this goal, sustainability must be vertically integrated at three organizational levels (corporate, divisional and operational) and three functional levels (strategy, planning and implementation)

Micromachined capacitive displacement sensor for long-range nano-positioning

Integrated long-range position sensing with high accuracy will be of paramount importance for high-potential applications in a.o. future probe-based datastorage and microscopy applications [1], provided that nm position accuracy can be obtained over a range of tens of micrometers or more. This work presents the design, fabrication and measurements for an integrated incremental capacitive long-range position sensor for nano-positioning of microactuators. For compactness, economical viability and optimal performance, the aim has been to fully integrate sensor and actuator through micromachining technology, without additional micro-assembly. Two related concepts are presented and evaluated through analysis, 2D-Finite-Element Simulations and experimental assessment. The sensors consist of two periodic geometries (period ≈ 8-16μm) on resp. a slider, movable in x-direction, and sense-structures, movable in y-direction, at both sides of the slider, Fig. 1. In ICMM the displacement of the slider is measured by measuring the periodic change in capacitance ΔCs(x) with a charge-amplifier and synchronous detection technique [2]. Using sense-actuators, the gap-distance between sense-structures and slider is made smaller than is possible with standard available photo-lithography (< 2 μm), thus increasing the capacitance and the S-N Ratio

Photodiodes based in La0.7Sr0.3MnO3/single layer MoS2 hybrid vertical heterostructures

The fabrication of artificial materials by stacking of individual two-dimensional (2D) materials is amongst one of the most promising research avenues in the field of 2D materials. Moreover, this strategy to fabricate new man-made materials can be further extended by fabricating hybrid stacks between 2D materials and other functional materials with different dimensionality making the potential number of combinations almost infinite. Among all these possible combinations, mixing 2D materials with transition metal oxides can result especially useful because of the large amount of interesting physical phenomena displayed separately by these two material families. We present a hybrid device based on the stacking of a single layer MoS2 onto a lanthanum strontium manganite (La0.7Sr0.3MnO3) thin film, creating an atomically thin device. It shows a rectifying electrical transport with a ratio of 103, and a photovoltaic effect with Voc up to 0.4 V. The photodiode behaviour arises as a consequence of the different doping character of these two materials. This result paves the way towards combining the efforts of these two large materials science communities.Comment: 1 table, 4 figures (+9 supp. info. figures

HREM studies of intergrowths in Sr2[Srn-1TinO3n+1] Ruddlesden-Popper phases synthesized by mechanochemical activation

A mechanochemical activation route has been applied in order to obtain the &lt;i&gt;n&lt;/i&gt;=1–4 and &#8734; members of the Sr&lt;sub&gt;2&lt;/sub&gt;[Sr&lt;sub&gt;n&lt;/sub&gt;&lt;sub&gt;−1&lt;/sub&gt;Ti&lt;sub&gt;n&lt;/sub&gt;O&lt;sub&gt;3n+1&lt;/sub&gt;] Ruddlesden– Popper series from different (&lt;i&gt;n&lt;/i&gt;+1)SrO:nTiO&lt;sub&gt;2&lt;/sub&gt; mixtures. The mechanosynthesis of SrTiO&lt;sub&gt;3&lt;/sub&gt; and Sr&lt;sub&gt;2&lt;/sub&gt;TiO&lt;sub&gt;4&lt;/sub&gt; was observed during the milling process from the initial stoichiometric mixture, but in the cases of the &lt;i&gt;n&lt;/i&gt;=2–4 members, a subsequent thermal treatment was needed. The synthesis protocol of Sr&lt;sub&gt;3&lt;/sub&gt;Ti&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;7&lt;/sub&gt; has been greatly improved and this compound can be isolated as a single, crystalline phase after annealing at 800&#176;C. In the case of Sr&lt;sub&gt;4&lt;/sub&gt;Ti&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;10&lt;/sub&gt; and Sr&lt;sub&gt;5&lt;/sub&gt;Ti&lt;sub&gt;4&lt;/sub&gt;O&lt;sub&gt;13&lt;/sub&gt;, the formation temperature was also decreased, but members with &lt;i&gt;n&lt;/i&gt;=3 and 4 could not be isolated. Detailed investigations using electron microscopy methods (TEM, HREM and SAED) were carried out in the samples corresponding to &lt;i&gt;n&lt;/i&gt;=2–4. Although a single ordered Sr&lt;sub&gt;3&lt;/sub&gt;Ti&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;7&lt;/sub&gt; structure is dominant in the sample corresponding to &lt;i&gt;n&lt;/i&gt;=2, a few intergrowths of other Ruddlesden–Popper phases were observed. In the cases of &lt;i&gt;n&lt;/i&gt;=3 and 4, the intergrowths of Ruddlesden–Popper phases are more frequent than in the &lt;i&gt;n&lt;/i&gt;=2 composition and are randomly distributed in the sample. The more frequent occurrence of such stacking faults, with increasing &lt;i&gt;n&lt;/i&gt; value, leads to a somewhat disordered layer stacking sequence

Environmental sustainability in the mining sector: evidence from Catalan companies

This paper examines the adoption of environmental practices in small and medium sized companies inthe surface mining industry in Catalonia (Spain). To fulfill this aim, a survey of 41 items concernint environmental management systems and environmentally sustainable practices has been conducted. Results show that companies have committed themselves to environmental and sustainable issues. The majority of companies claim to understand the effects of their activities on the environment and they care for responsible access and management of natural resources. Restoration plans and the annual waste declaration are mandatory in Catalonia, and rational resources exploitation practices have been adopted by a high percentage of mines. Finally, some examples of good environmentally sustainable practices are introduced.Peer ReviewedPostprint (author’s final draft

Deformation of the Fermi surface in the extended Hubbard model

The deformation of the Fermi surface induced by Coulomb interactions is investigated in the t-t'-Hubbard model. The interplay of the local U and extended V interactions is analyzed. It is found that exchange interactions V enhance small anisotropies producing deformations of the Fermi surface which break the point group symmetry of the square lattice at the Van Hove filling. This Pomeranchuck instability competes with ferromagnetism and is suppressed at a critical value of U(V). The interaction V renormalizes the t' parameter to smaller values what favours nesting. It also induces changes on the topology of the Fermi surface which can go from hole to electron-like what may explain recent ARPES experiments.Comment: 5 pages, 4 ps figure

Deformation of the Fermi surface in the extended Hubbard model

The deformation of the Fermi surface induced by Coulomb interactions is investigated in the t-t'-Hubbard model. The interplay of the local U and extended V interactions is analyzed. It is found that exchange interactions V enhance small anisotropies producing deformations of the Fermi surface which break the point group symmetry of the square lattice at the Van Hove filling. This Pomeranchuck instability competes with ferromagnetism and is suppressed at a critical value of U(V). The interaction V renormalizes the t' parameter to smaller values what favours nesting. It also induces changes on the topology of the Fermi surface which can go from hole to electron-like what may explain recent ARPES experiments.Comment: 5 pages, 4 ps figure