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Copper based halide-perovskites ACuF3 (A = Mg and Ca) have been studied for potential application as an electrode material. Structural, electronic, elastic and optical properties of these compounds are investigated by utilizing the wien2k code within density functional theory. Structural study reveal that both compounds have stable and cubic perovskite structure with optimized lattice constants 4.07 Å and 4.15 Å having space group pm-3m 221. Electronic analysis reveals that both compounds have metallic nature. Through IR-Elast package the elastic constants are evaluated and by utilizing these constant various elastic parameters like bulk modulus, shear modulus, Kleinman parameter, Anistropic factor are analyzed. Both compounds are found to be mechanically stable with ductile nature. Furthermore, the various optical parameters such as dielectric function, refractive index, optical conductivity, reflectivity and absorption coefficient are studied. The seebeck coefficient, electrical conductivity and electronic thermal conductivity are studied through BoltzTrap. The study reveals that MgCuF3 and CaCuF3 can be potential candidates for electrode materials.

International audience; Quasi two-dimensional hybrid organic-inorganic perovskites (HOIPs) have been rediscovered recently for photovoltaics due to a higher stability than other HOIPs. We focus here on the electronic structure of the 2D perovskite (C6H5C2H4NH3)2PbI4. We perform an experimental k-resolved determination of the valence and conduction bands by angle-resolved photoemission spectroscopy (ARPES) and inverse photoemission spectroscopy (IPES). The experimental and theoretical dispersions are compared. The valence band width is in agreement with that of renormalized theoretical bands, while no significative renormalization is observed for the conduction band. The effect of the spin-orbit coupling in the conduction band is also experimentally observed.

This study aimed to develop a practical and accurate 4-dimensional (4D) magnetic resonance imaging (MRI) method using a non-navigator, image-based internal respiratory surrogate derived by dimensionality reduction (DR). The use of DR has been previously suggested but not implemented for reconstructing 4D MRI, despite its practical advantages. We compared multiple image-acquisition schemes and refined a retrospective-sorting process to optimally implement a DR-derived surrogate. The comparison included an unconventional scheme that acquires paired slices alternately to mitigate the internal surrogate's dependency on a specific slice location. We introduced 'target-oriented sorting', as opposed to conventional binning, to quantify the coherence in retrospectively sorted images, thereby determining the minimal scan time needed for sufficient coherence. This study focused on evaluating the proposed method using digital phantoms which provided unequivocal gold standard. The evaluation indicated that the DR-based respiratory surrogate is highly accurate: the error in amplitude percentile of the surrogate signal was less than 5% with the optimal scheme. Acquiring alternating paired slices was superior to the conventional scheme of acquiring individual slices; the advantage of the unconventional scheme was more pronounced when a substantial phase shift occurred across slice locations. The analysis of coherence across sorted images confirmed the advantage of higher sampling efficiencies in non-navigator respiratory surrogates. We determined that a scan time of 20 s per imaging slice was sufficient to achieve a mean coherence error of less than 1% for the tested respiratory patterns. The clinical applicability of the proposed 4D MRI has been demonstrated with volunteers and patients. The diaphragm motion in 4D MRI was consistent with that in dynamic 2D imaging which was regarded as the gold standard (difference within 1.8 mm on average).

This work reports experimental and computational magnetic phase transition from superconducting-diamagnet to ferromagnet in lanthanum (La)-doped functionalized Nb2C MXene. Co-precipitation method is used to synthesize La-doped Nb2C MXene. Structure and morphology of the compound are studied through x-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy and energy dispersion spectroscopy, confirming the successful doping of La while retaining the two-dimensional (2D) structure of MXene. The magnetic properties of doped sample are studied using field-cooled and zero-field-cooled curves as well as from magnetization (M) versus applied magnetic field (H) graphs. Contrary to the superconductivity-like diamagnetic behavior in pristine Nb2C MXene, the La-doped MXene converts the diamagnetism into the ferromagnetic (FM) phases at all temperatures. The ferromagnetism arises due to the pinning of magnetic spins pinned by Lanthanum itself. The computational analysis of pristine Nb2C MXene confirms its diamagnetic behavior and further clarifies the role of La and functional groups (O and F) in the reduction of diamagnetic behavior in La-doped Nb2C MXene while inducing FM nature. This work provides an interesting superconducting-diamagnetic to FM transition with a possibility of its implementation in 2D spintronics.

The arrangement of B~atoms in a doped Si(111)-$(\sqrt{3}\times\sqrt{3})R30^{\circ}$:B system was studied using near-edge x-ray absorption fine structure (NEXAFS). Boron atoms were deposited via segregation from the bulk by flashing the sample repeatedly. The positions of B~atoms are determined by comparing measured polarized (angle-dependent) NEXAFS spectra with spectra calculated for various structural models based on ab-initio total energy calculations. It is found that most of boron atoms are located in sub-surface L$_{1}^{c}$ positions, beneath a Si atom. However, depending on the preparation method a significant portion of B~atoms may be located elsewhere. A possible location of these non-L$_{1}^{c}$-atoms is at the surface, next to those Si atoms which form the $(\sqrt{3}\times\sqrt{3})R30^{\circ}$ reconstruction., 9 pages, 8 figures

The aim of this research is to utilize the waste generated in concrete. Brick dust is lavish material which on dumping not only occupy land but also it has environmental problems which is hazardous to livings. This waste is generated in brick kilns, brick masonry construction sites and during transportation. By recycling brick dust the problem could be solved up to some extent. In this research, brick dust was used in plain cement concrete to check its fresh and hardened properties. Brick dust was used to check the workability and strength of concrete, using the water-cement ratio of 0.55 which was kept constant during research. Three samples were cast for each 3, 7, 14, 28 and 56 days with 0%, 5%, 10% 15% and 20% incorporation of brick dust. The test results reveals that replacing cement with brick dust shows higher workability than control sample for 5%, 10% and 15%, of which 15% was greater of all. However, strength results were quite competitive, replacing cement with 15% brick dust shows higher compressive strength. The split tensile test were also conducted, which shows high tensile strength by replacing cement with 15% brick dust. This research shows that cement can be replaced with brick dust.

This paper illustrates the partial replacement of cement by brick dust and lime powder. The environmental condition is getting worse around the globe. One of the major causes of environment is waste generated from factories and working sites. The waste goes into dumping which not only occupy land but also cause ill effects to living. This unruly can be solved up to some degree by using these wastes in concrete as a cement replacement. An effort is made in this research to use lime powder and brick dust in plain concrete as cement replacement. The lime powder and brick dust was first used separately in concrete and then used a combination of brick dust and lime powder. Lime powder and brick dust was used separately in concrete up to 20% replacement with 5% interval. Than 5% brick dust was used with 15% lime powder, 10% brick dust with 10% lime powder, 15% brick dust with 5% lime powder. Using 20% brick dust separately in concrete gives good workability but less compressive strength compared to control sample. Replacing cement by 20% lime powder enhanced 3% compressive strength and split tensile strength compared to control mix. Whereas replacing cement with 15% lime powder and 5% brick dust gives optimum compressive strength and tensile strength compared to control mix. The results shows that lime powder increase the compressive strength and tensile strength compared to concrete made with brick dust. Using 20% lime and brick dust can save cost of cement in range of 7.2%- 12.5% which ultimately save the cost of a project.

Natural and synthetic uytenbogaardtite (Ag3AuS2) polymorphs have been studied for their structural, compositional and thermodynamic properties. We investigated their electronic and optical properties for the first time using density functional theory. These calculations are based on the full potential linearized augmented plane wave method using the modified Becke–Johnson potential. Our calculations reveal that Ag3AuS2 is a direct band gap semiconductor exhibiting three crystal phases, cubic, trigonal and triclinic. The calculated band gaps for cubic, trigonal and triclinic phases are 1.15, 2.15 and 1.73 eV, respectively. The band gaps of the Ag3AuS2 polymorphs in the near infrared and visible region highlight the importance of these polymorphs for optoelectronic applications such as resistive switches, low-loss optical fibers, thin-film solar cells and thin-film photovoltaic devices. Furthermore, our calculations show that the electronic and optical properties of Ag3AuS2 are crystal phase dependent.

Optoelectronic properties of the Nitrido-magneso-silicates Ca[Mg3SiN4], Sr[Mg3SiN4], and Eu[Mg3SiN4] compounds have been investigated using the relativistic full-potential augmented plane-wave method (FLAPW) based on the density functional theory (DFT). The calculations of the electronic and optical properties were conducted by using the local density approximation (LDA), generalized gradient approximation (GGA), and modified Becke Johnson (mBJ) potential. A study of the band structures shows that these compounds are indirect band gap materials. We found a great variation in the obtained energy band gap value as we changed the functionals. The mBJ functional leads to a greater band-gap value compared to LDA and GGA cases. Based on the calculated electronic structure, the optical properties computed, such as the complex dielectric function, absorption coefficient, reflectivity, energy loss function and refractive index, were functions of the photon energy. Origins of the spectral peaks in the optical spectra were discussed and assigned to different electronic transitions observed from the electronic structure calculation.

The increase in energy demands is leading to growing interest in new thermoelectric inorganic materials, such as the chalcogenides. The recently synthesized quaternary chalcogenide, Tl2PbXY4 (X = Zr, Hf and Y = S, Se), compounds were investigated using the full potential linear augmented plane wave method based on density functional theory. We used the generalized gradient approximation plus the optimized effective Hubbard parameter U to treat the exchange correlation. The existence of heavy metals (Tl, Pb and Hf) required the application of relativistic spin–orbit coupling via a second variational procedure. Tl2PbHfS4, Tl2PbHfSe4, Tl2PbZrS4 and Tl2PbZrSe4 compounds were found to be semiconductors with indirect band gaps of 0.911, 0.659, 0.983 and 0.529 eV, respectively. The types of carriers and electrical transport properties of Tl2PbXY4 (X = Zr, Hf and Y = S, Se) are attributed to the Tl-d and S/Se-s electronic states near the Fermi level. Optical properties were investigated via the calculation of dielectric function and reflectivity. Using Boltzmann theory, we compared the thermoelectric properties and we found that Tl2PbHfS4 could be a good candidate for thermoelectric devices.