Structural, elastic, electronic, optical and anisotropy properties of newly quaternary Tl2HgGeSe4 via DFPT predictions associated to XPES and RS experiments.

In the present work, we report on theoretical studies of thermodynamic properties, structural and dynamic stabilities, dependence of unit-cell parameters and elastic constants upon hydrostatic pressure, charge carrier effective masses, electronic and optical properties, contributions of interband transitions in the Brillouin zone of the novel TlHgGeSe crystal. The theoretical calculations within the framework of the density-functional perturbation theory (DFPT) are carried out employing different approaches to gain the best correspondence to the experimental data. The present theoretical data indicate the dynamical stability of the title crystal and they reveal that, under hydrostatic pressure, it is much more compressible along the a-axis than along the c-axis.

Thermal Stability and Non-Linear Optical and Dielectric Properties of Lead-Free KBiTiO Ceramics.

Lead-free KBiTiO (KBT) ceramics with high density (~5.36 g/cm, 90% of X-ray density) and compositional purity (up to 90%) were synthesized using a solid-state reaction method. Strongly condensed KBT ceramics revealed homogenous local microstructures.

Effect of Covalence and Degree of Cation Order on the Luminous Efficacy of Mn Luminescence in the Double Perovskites, BaTaO ( = Y, Lu, Sc).

The spectroscopic properties of the Mn ion are investigated in the series of isostructural double perovskite compounds, BaTaO ( = Y, Lu, Sc). A comparison of these properties highlights the influence of covalent bonding within the perovskite framework and the degree of order between the B-Ta cations on the energy and intensity of the MnE → A emission transition (R-line). These two parameters of the emission spectrum are of importance for practical application since they determine the phosphor luminous efficacy.

Electronic, Optical, and Vibrational Properties of an AgAlS Crystal in a High-Pressure Phase.

The aim of this study is to comprehensively examine the structural composition and properties of the AgAlS crystal during its high-pressure phase. This analysis delves into the second coordination environment of the crystal structure and elucidates the distinct transformations it undergoes during the phase transition. The band energy structure was calculated, and the origin of electronic levels was clarified.

Insights from Experiment and Theory on Peculiarities of the Electronic Structure and Optical Properties of the TlHgGeSe Crystal.

TlHgGeSe crystal was successfully, for the first time, synthesized by the Bridgman-Stockbarger technology, and its electronic structure and peculiarities of optical constants were investigated using both experimental and theoretical techniques. The present X-ray photoelectron spectroscopy measurements show that the TlHgGeSe crystal reveals small moisture sensitivity at ambient conditions and that the essential covalent constituent of the chemical bonding characterizes it. The latter suggestion was supported theoretically by ab initio calculations.

Study on Local-Structure Symmetrization of KXF Crystals Doped with Mn Ions by First-Principles Calculations.

The crystals of Mn-activated fluorides, such as those of the hexafluorometallate family, are widely known for their luminescence properties. The most commonly reported red phosphors are AXF: Mn and BXF: Mn fluorides, where A represents alkali metal ions such as Li, Na, K, Rb, Cs; X=Ti, Si, Ge, Zr, Sn, B = Ba and Zn; and X = Si, Ge, Zr, Sn, and Ti. Their performance is heavily influenced by the local structure around dopant ions.

Influence of Isostatic Pressure on the Elastic and Electronic Properties of KSiF:Mn.

Isostatic pressure effects on the elastic and electronic properties of non-doped and Mn-doped KSiF (KSF) have been investigated by first-principles calculations within density functional theory (DFT). Bulk modulus was obtained by the Murnaghan's equation of states (EOS) using the relationship between volume and pressures at pressures between 0 and 40 GPa, and elastic constants were calculated by the stress-strain relationship giving small distortions at each pressure point. The other elastic parameters such as shear modulus, sound velocity and Debye temperature, which can be obtained from the elastic constants, were also estimated.

First Principles Calculations of Atomic and Electronic Structure of TiAl3+- and TiAl2+-Doped YAlO.

In this paper, the density functional theory accompanied with linear combination of atomic orbitals (LCAO) method is applied to study the atomic and electronic structure of the Ti and Ti ions substituted for the host Al atom in orthorhombic bulk YAlO crystals. The disordered crystalline structure of YAlO was modelled in a large supercell containing 160 atoms, allowing simulation of a substitutional dopant with a concentration of about 3%. In the case of the Ti-doped YAlO, compensated -center (oxygen vacancy with two trapped electrons) is inserted close to the Ti to make the unit cell neutral.

Entropy-Induced Multivalley Band Structures Improve Thermoelectric Performance in -CuP(SSe) Argyrodites.

Searching for novel low-cost and eco-friendly materials for energy conversion is a good way to provide widespread utilization of thermoelectric technologies. Herein, we report the thermal behavior, phase equilibria data, and thermoelectric properties for the promising argyrodite-based CuP(SSe) thermoelectrics. Alloying of CuPSe with CuPS provides a continuous solid solution over the whole compositional range, as shown in the proposed phase diagram for the CuPS-CuPSe system.

Identification of MVOCs Produced by and Growing on WPC Boards by Using Subtraction Mass Spectra.

Volatile fungal metabolites are responsible for various odors and may contribute to a "sick building syndrome" (SBS) with a negative effect on the heath of building. The authors have attempted to fill the research gaps by analyzing microbial volatile organic compounds (MVOCs) originating from representatives of the class that grow on wood-polymer composite (WPC) boards. WPCs have been analyzed as a material exposed to biodeterioration.

Manifestation of Anomalous Weak Space-Charge-Density Acentricity for a TlHgBr Single Crystal.

Density functional theory (DFT) calculations within the concept of the MBJ+U+SO (modified Becke-Johnson potential + U + spin orbit) approach were performed for a TlHgBr single crystal for the first time assuming weak noncentrosymmetry (space group P4nc). Excellent agreement was achieved between the calculated and experimental band-gap-energy magnitudes as well as the density of electronic states measured by the X-ray photoelectron spectroscopy method. It is a very principal result because usually the DFT calculations underestimate the energy-gap values.

Trigeminal neuralgia occurring after the third dose of Pfizer BioNTech COVID-19 vaccine. Complication or coincidence? An illustrative case report and literature review.

The coronavirus disease 2019 pandemic is an ongoing concern for medical care worldwide. Since its emergence, multiple COVID-19 vaccines have been designed, allowing for more effective control of the pandemic. COVID-19 vaccines, like any other form of medical intervention, may cause adverse and unforeseen side effects, varying in frequency and severity.