Lead-free ferroelectric electrocaloric ceramics that could convert electrical energy into heat are the promising candidate for environment-friendly cooling devices. For refrigeration devices, a large temperature change (ΔT) and good temperature stability are required, which are highly related to the phase structure and the applied electric field. In this work, a diffused ferroelectric–paraelectric (FP) phase transition is formed in (K, Na)NbO3 (KNN) by using appropriate composition engineering. The relaxor ferroelectrics in this work present both a large ΔT of 1.24 K and a high ΔT/ΔE of 0.19 K mm/kV. In addition, a wide temperature span exceeds 55 °C at the high electrocaloric effect (ECE) criterion (ΔT ≥ 0.5 K) could also be observed. This work not only opens a new strategy for obtaining high-performance ceramics for refrigeration devices but also extends the application area of the KNN-based lead-free ferroelectrics from sensors, actuators and energy harvesting to solid-state cooling applications.

Bentonite is the most widely used foundry binder. Most of the iron castings are made in greensand systems which make use of bentonite as a binder. The bentonite used in greensand moulding is usually activated with sodium carbonate to achieve desirable properties. Activation of bentonite is known to improve mould related properties like giving a high wet tensile strength and improving the durability. The practice of activation is more common with calcium bentonite. A number of bentonite deposits tend to remain unbeneficiated due to their low cation exchange capacity (CEC) which are regarded as low quality commercial grade. The primary characteristic that shows the increased activation is the swelling index of the bentonite. This study investigated the influence of rehydration and activation in improving the quality of low commercial grade sodium bentonite. The bentonite samples were activated with sodium carbonate. Rehydration and activation was seen to improve the CEC and swelling index. The increase in CEC and swelling index was however not consistent with the gains in sodium.

In the present study we employ electronic structure calculations (based on Density Functional Theory -DFT approach) and Fully Atomistic Reactive Molecular Dynamics (FARMD) simulations (based on ReaxFF reactive force field) to evaluate the reactivity of branched polyfuran (PF) derivatives and identify promising systems for chemical sensing. Condensed-to-atoms Fukui indexes (CAFI) were employed to identify the most reactive sites on the oligomers structure. The chemical sensing abilities of the most promising systems were evaluated via FARMD simulations in the presence of distinct gaseous compounds. The results indicate the derivatives PF-CCH and PF-NO₂ (i.e. CCH and NO2 as side groups) as the most promising systems for chemical sensor applications, presenting higher reactivity on the most accessible sites. An interesting correspondence between DFT and MD results was also identified, suggesting the plausibility of using CAFI parameters for the identification of improved materials for chemical sensors.

Lack of data on available agriwaste by type of source, local variations in agricultural consumption, and the uncertain feasibility of industrial scaling, all contribute to the challenges of developing commercially viable agriwaste-to-resource building products. Materials Passports linked to Building Management Information systems are tools that can improve regional planning efforts and the coordination of sustainable supply chains focused on new product development and product stewardship.

Globally, an estimated 3.5 kg per capita of daily agricultural waste is transferred to municipal landfills. Stated differently, 7.8 billion people generate 26.25 billion kg of daily agriwaste. Numerous studies established linkages between leachates from solid waste landfills, bioaccumulation of toxic chemicals, and greenhouse gas emissions that are a leading cause of climate change. Furthermore, raw material scarcity threatens to constrain economic growth and productivity. Sustainable circular economy practices focus on increased efficiency and a decoupling of wasted natural resource consumption from economic growth. Academic and industry researchers are focused on developing circular economy solutions that increase resource efficiency while decoupling wasted natural resource consumption from economic growth. Human acceptance and adaptation of technology are ideologically, culturally, and socio-technically dependent. Waste banana peels are used as an analytical scenario of how BIM modeling can improve the production of localized, affordable, and culturally appropriate building materials. Ideological and cultural norms are a precursor for socio-technical acceptance. Building material selection is examined from the perspective of complex factors creating uncertain economic valuations, and socio-cultural variations in the definition of waste. The objective of the research is to open multidisciplinary examination of the practices and choices that determine affordably safe building materials.

The substitutional solid solutions in the Bi(Gd) - Fe - O and Bi(Nd) - Fe - O systems of the Bi1-xGdxFeO3 and Bi1-xNdxFeO3 types with x up to 0.20 were synthesized by the solid-state reaction method and investigated using X-ray diffraction analysis and infrared reflective spectrometry in the wavelength range from 12.5 to 24 μm. It was determined that the Bi1-xGdxFeO3 and Bi1-xNdxFeO3 crystal structure is a distorted form of perovskite, R3c space group. Two extremums at 18.2 μm (strong extremum) and 22.5 μm (rather weak extremum) on the infrared reflection spectra of the Bi1-xGdxFeO3 and Bi1-xNdxFeO3 solid solutions were discovered. The extremum at 18.2 μm corresponds to the Fe – O stretching vibrations and the extremum at 22.5 μm corresponds to the O - Fe – O bending vibrations of the FeO6 groups. The growth of reflectivity of the Bi1-xGdxFeO3 and Bi1-xNdxFeO3 solid solutions in comparison with pure BiFeO3 and the displacement of the reflectivity band maximum into the side of the spectrum with longer wavelengths with the increase of the atomic part of the substitutive element x up to 0.20 were found.

Prompted by the success in functionalizing 2D sheets of MoS2 and MoSe2 by their reaction with organic halides, we have investigated the functionalization of layered tungsten chalcogenides, WS2, WSe2, and WTe2, by their reaction with substituted iodobenzenes as well as fluorophores based on pyrene and coumarin. Carbon–chalcogenide bonds are formed readily in the case of metallic chalcogenides while there is need for the Pd(0) catalysts in the case of insulating chalcogenides. Thus, the formation of carbon–chalcogen (S, Se, and Te) bonds is accomplished with the metallic 1T as well as the semiconducting 2H phases of the tungsten chalcogenides. Functionalization in the case of substituted iodobenzenes is favored by the electron withdrawing groups in the benzene ring. Interestingly, functionalization has been successful with other insulating layered chalcogenides such as GaS and GaSe. Reaction with organic halides emerges as a general method for the covalent functionalization of chalcogenide nanosheets, suggesting the possible use of this strategy to functionalize various chalcogenide structures.

Replacing liquid by solid state electrolytes has the potential to significantly improve current Li ion batteries concerning performance and safety. The material class NZP, based on the compound NaZr2(PO4)3, exhibits a structural framework suitable for ionic conduction. In this work, a systematic compositional screening and simulation approach, combining classical molecular-dynamics, first-principles calculations, and structural analysis was applied, with which a set of new Li ion conducting NZP compounds could be identified.

Recent studies on graphene hydrogenation processes showed that hydrogenation occurs via island growing domains, however how the substrate can affect the hydrogenation dynamics and/or pattern formation has not been yet properly investigated. In this work we have addressed these issues through fully atomistic reactive molecular dynamics simulations. We investigated the structural and dynamical aspects of the hydrogenation of graphene membranes (one-side hydrogenation, the so called graphone structure) on different substrates (graphene, few-layers graphene, graphite and platinum). Our results also show that the observed hydrogenation rates are very sensitive to the substrate type. For all investigated cases, the largest fraction of hydrogenated carbon atoms was for platinum substrates. Our results also show that a significant number of randomly distributed H clusters are formed during the early stages of the hydrogenation process, regardless of the type of substrate. These results suggest that, similarly to graphane formation, large perfect graphone-like domains are unlikely to be formed. These findings are especially important since experiments have showed that cluster formation influences the electronic transport properties in hydrogenated graphene.

The rare earth (RE) mineral loparite with the chemical composition (RE, Na, Sr, Ca)(Ti, Nb, Ta, Fe+3)O3 is the principal ore of the light rare earth elements (LREE) as well as niobium and tantalum. The enthalpies of formation of RE0.67-xNa3xTiO3 (RE = La, Ce) and Ca1-2xNaxLaxTiO3 from oxides and elements of lanthanum and cerium perovskites and their solid solutions have been obtained using high temperature oxide melt solution calorimetry. RE0.67-xNa3xTiO3 (RE = La, Ce) perovskites become more stable relative to oxide components as sodium content increases. Na0.5Ce0.5TiO3 and Na0.5La0.5TiO3 can be considered stable endmembers in natural loparite minerals. For perovskite solid solutions Ca1-2xNaxLaxTiO3, the enthalpies of formation from the constituent oxides $\Delta {\rm{H}}_{{\rm{f}},\,{\rm{ox}}}^^\circ$ become more exothermic with increasing Na+La content, suggesting a stabilizing effect of the substitution 2Ca2+ → Na+ + La3+ on the perovskite structure. The trend of increasing thermodynamic stability with decreasing structural distortion is similar to that seen in many other ABO3 perovskites.

YCrO3 (YCO) is known to be a multiferroic with orthorhombic,Pnma, structure with center of inversion. However, thelocal structural inhomogeneity in this compound is believed to give rise toferroelectric behavior. In this study we explore high temperature Ramaninvestigations of YCO and observed that one of its Raman mode B3g (3)(CrO6 Octahedral tilt mode) softens around the structural phasetransition which could be the origin of ferroelectric nature in YCO. Inaddition, we substitute bismuth (Bi) in YCO to understand the structuraldistortions that lead to local structural inhomogeneity. Besides B3g(3) mode softening with composition and high temperature studies inY1-xBixCrO3 the study reveals thestructural distortions and the structural tunability Bi offers in suchsystems.

Phase pure Pb[(Fe0.5-xScx)Nb0.5]O3 [x= 0 to 0.5] multiferroic relaxors have been synthesized to study theeffect of Sc on dielectric phase tansition. Rietveld refinement of x-raydiffraction patterns confirm that the structure transforms from monoclinic (Cm)to rhomobohedral (R3m) at x = 0.3. Absence of low frequency dielectricresponse in compositions with low Sc content attributed to interfacialpolarizabilty arising due to differences in conductivities of grain and grainboundary. Moreover, value of diffusivity parameter (γ) of high of Sccontent compositions is near to 2, confirms relaxor charactertistic of thesecompositions. However, an essential feature of relaxors i.e., frequencydependent dielectric permittivity as a function of temperature is observed onlyin x = 0.5 composition[Pb(Sc0.5Nb0.5)O3 (PSN)]. In addition,ferroelectric phase transition temperature (Tmax) increases initiallyat lower Sc content (upto x ≤ 0.25), and further drops beyond x≥ 0.3. Such behavior of Tmax in these compositions is due to theonset of B'-B" local cation ordering at x = 0.3. Hightemperature Raman spectra of Pb(Sc0.5Nb0.5)O3(x = 0.5) confirm the stability of cation ordering in compositions withhigh Sc content well above the phase transition temperature.

We present our findings on structural features and trends observed in single crystal structural studies for a series of oligothiophene and ethylenedioxythiophene (EDOT) molecules substituted with bromo and tricyanovinyl groups. The presence of a C=C bridge as well as the introduction of n-butyl solubilizing groups are also addressed. Focus of the work will be on how these structural modifications, in particular, how inter- and intra- molecular interactions impact planarity and packing of molecules in the observed crystal structures.

Synthetic chemists are paying ever more attention to enabling technologies as a means to opening the paths towards the double goal of achieving high efficiency and meeting green criteria. Non-conventional techniques that create unique environments which promote selective modification have been investigated by many as part of the search for more highly efficient synthetic derivatization of cyclodextrins (CD). A few optimized microwave-assisted protocols have so far been developed for the preparation of selective per-alkylated aminocyclodextrin. In this work, a series of β-CD derivatives, whose primary hydroxyls were all replaced by amino groups, has efficiently been synthesized from per-(6-iodo-6-deoxy)-β-CD via nucleophilic substitution with amines under microwave irradiation in closed vessel (N2 pressure). The reduction of per-(6-azido-6-deoxy)-β-CD to per-(6-amino-6-deoxy)-β-CD via catalytic hydrogenation has also been successfully carried out under dielectric heating.

Self-compacting concretes have been of topical interest due to the ease of adoption and the significant savings in compaction efforts particularly at the congested reinforcement locations, in spite of the leak-proof forms required. However, many of the aspects regarding their production with different powder or pozzolanic additions and their corresponding mechanical strength characteristics are not yet fully understood. This paper deals exclusively with the compressive strength characteristics of these concretes incorporating limestone powder as a mineral admixture through the water cement ratio to strength results of concretes reported in literature. The basic idea is to get an idea of the SCCs at the lowest and the highest possible amounts of the limestone powder in it.

Fluorine substitution in CaH2 has been studied by means of experimental and theoretical methods. Samples with various compositions have been prepared by ball milling. In situ X-ray diffraction analysis has been carried out as a function of temperature by synchrotron radiation experiments. An increase of mixing has been observed during heating, suggesting that mixing is thermodynamically favoured but it is kinetically hindered at low temperatures. Ab initio DFT calculations have been performed to estimate the thermodynamic mixing properties of both orthorhombic and cubic solid solutions. On the basis of ab initio results and literature information, a thermodynamic assessment within the CALPHAD framework has been performed and the pseudo binary CaH2-CaF2 phase diagram has been calculated. The formation of orthorhombic and cubic terminal solid solutions in the CaH2-CaF2 system is predicted, in good agreement with experimental findings.

A series of red-emitting phosphors with compositions of La2(Mo1−zSiz)2O9:0.05Eu3+ (0 ≤ z ≤ 0.10) with strong near-UV absorption were prepared by solid-state method. The structure and luminescence properties were investigated by x-ray powder diffraction, UV–vis diffuse reflectivity, and photoluminescence spectra. The luminescent properties as a function of Si4+ concentrations were systematically studied. Under excitation of a wide range near-UV (250–430 nm) or blue light, Si4+-doped series phosphors exhibit characteristic red emission of Eu3+ peaked at 615 nm. The incorporation of Si4+ into La2Mo2O9:0.05Eu3+ phosphor leads to the improvement of the excitation broad band and sharp peaks, as well as the broadening of charge transfer band. Appropriate amount of Si4+ doping can enhance the red luminescence intensity. Finally, the possible reasons for the luminescence enhancement via the corporation of Si4+ were explained.

The dependences of unit cell parameter, x-ray diffraction line width B, and microhardness H on the composition of PbTe-Bi2Te3 (0–10 mol% Bi2Te3) semiconductor alloys, subjected to different types of heat treatment, were obtained. In the concentration ranges ∼0.5–1.5 and 3–4 mol% Bi2Te3 within the homogeneity region of PbTe (0–6 mol% Bi2Te3), anomalous constancy or decrease in B and H was observed. A long room temperature aging leads to a more distinct manifestation of these effects. It is suggested that the observed peculiarities in the concentration dependences of the properties are connected with percolation effects and self-organization processes in the solid solution.

Multi-component small molecule systems that are amphiphilic or that can hydrogen bond end-to-end or side-to-side have been shown to self-assemble into a variety of shapes including fibers, rods, sheets, plates, spheres, and tubes. Recently, we have identified a simple route to self-assemble the same shapes from one-component systems. The structures form by attaching ethyl vinyl sulfone (EVS) to amino acids in water at room temperature. Choice of amino acid, amount of EVS substitution, and solvent conditions determine the final shape. Functionalized amino acids spontaneously form structures like fibers, spheres, tubes, and donuts when dried from solution. Here we focus on fibers and tubes.

A new melt processing route for the fabrication of large grain Gd-Ba-Cu-O (GdBCO) bulk superconductors has been developed based on the use of novel GdBa4Cu3O8−δ (Gd-143) and GdBa6Cu3O10−δ (Gd-163) precursor compositions. The new processing route enables the fabrication of large single grains from precursor powders that contain high concentrations of Ba. The superconducting properties and microstructures of GdBCO single grains with extra Ba fabricated via this new processing route are reported. Most importantly, the possible formation of a new form of Gd1+xBa2−xCu3O7−δ solid solution (Gd-123ss) with x < 0 in single grains fabricated from the Ba-rich precursor are discussed for the first time based on the superconducting, chemical, and structural properties of the large GdBCO grains.

Interaction between nitrogen-substituted graphene-like compounds and hydrogen was investigated using ab initio molecular orbital method in the aspect of hydrogen storage. We adopted coronene as a model compound for fragmented graphene-like carbon materials and compared the interaction between hydrogen and pure or N-substituted coronenes by changing nitrogen positions. Among the assumed 19 N-substituted models, polarozabilities and HOMO–LUMO gaps were compared to evaluate physisorption and chemisorption energies. As for chemisorption, two N-substituted models were selected and closely examined to reveal the dependence on both nitrogen-substitution and hydrogen-adsorption positions. Potential energy surfaces as a function of H–H bond length and H2–coronen distance showed that the barrier height for hydrogen chemisorption strongly depends on N-substitution positions. The chemisorbed products of N-substituted coronenes are stabilized or destabilized compared with the pure carbon case depending on the sites of N-substitution and H-adsorption. These results suggest that N-substitution at certain positions possibly improve hydrogen storage properties of graphene-like materials.