NOTXT

ABSTRACT The paper outlines the successful synthesis of polycrystalline Nd0.5Ce0.5FeO3 through the sol–gel technique. The chosen compound is determined to possess an orthorhombic structure with the Pnma space group, indicating a well-defined crystalline structure. Regarding electrical properties, the material exhibits semiconductor characteristics, following the NSPT model for conduction. The activation energy (Ea) for conduction is measured at 0.337 eV, indicative of favorable conductivity. While dielectric measurements highlight a relaxation process within the Nd0.5Ce0.5FeO3 sample. Furthermore, direct optical transitions are observed in the compound with an energy gap (Eg⁣) of 1.73 eV, along with an estimated Urbach energy (Eu⁣) of 0.523 eV, indicating low disorder within the material. Overall, these findings underscore the multifaceted potential of Nd0.5Ce0.5FeO3, positioning it as a versatile material for various technological applications, including conductivity, dielectric behavior, infrared detection, and optical functionality such as solar energy conversion and photocatalysis.

ABSTRACT Two structural isomers of polymerisable perylene-tetracarboxylate columnar liquid crystals were designed and synthesized to investigate their liquid crystalline behavior, phase transition temperatures and luminescent properties. Polymerizable alkylene chains of varying lengths were attached to the highly conjugated perylene aromatic core to tune the mesophase transition temperatures and ranges. Wide mesophases with columnar-to-crystalline phase transition near room temperatures were achieved although longer flexible chains led to a destabilization of mesophases and a decrease in the clearing point. The UV-vis absorption and fluorescent emission measurements were conducted to evaluate their potential as promising polymerisable liquid crystalline organic semiconductors.

ABSTRACT The pressure-dependent structural, electronic and magnetic features of samarium monochalcogenides SmX (X = S, Se and Te) in the NaCl (B1), CsCl (B2), zinc blende (B3), wurtzite (B4) and NiAs (B8) phases are investigated. Employing density functional theory (DFT) with the Perdew–Burke–Ernzerhof generalized gradient approximation (PBE-GGA), the GGA + U approximation (where U denotes the Hubbard correlation term) and the FP-LAPW method, we predict metastable phases that have not been previously reported either experimentally or computationally. The present findings are consistent with the theoretical values and existing experimental results. According to the results, the rock-salt (B1) phase is the most stable. Based on band structure computations, these compounds exhibit metallic behavior in all phases. Spin-polarized calculations showed that the most stable state in the B1 phase is ferromagnetic (FM). Our study provides a platform for further experimental and theoretical work aimed at unravelling the potential applications of these materials.

ABSTRACT The current work focuses on the investigation of in-situ prepared NiO-Ce1-xNdxO2-δ and Ce1-yGdyO2-δ (NiO-CNO-CGO) (x = 0.05, 0.10 and y = 0.05, 0.10, 0.15 & 0.20) anode composites for their potential usage in SOFC applications. The TGA of a sample precursor showed a gradual weight loss until 600°C. The prepared compositions of NiO-CNO-CGO had XRD lattice constants that ranged from 4.180 to 4.187 for NiO and 5.406 to 5.416 for doped CeO2 phases. The use of FTIR verified the Ce–O–Ce bonds. The elemental compositions were investigated by EDX. Particle size analysis and SEM results showed the presence of nano- and micron-sized grains. The successful doping of Nd and Gd ions is demonstrated by shifts in the lower region of the Raman spectra. Among the anode specimens investigated, NiO-Ce0.90Nd0.10O2-δ-Ce0.95Gd0.05O2-δ specimen has resulted with highest conductivity (1.037 × 10−2 Scm−1) and moderate activation energy (0.270 eV) at 600°C in air.

ABSTRACT The critical exponents of the HoNi2 intermetallic alloy have been precisely obtained from the modified Arrott plots and the Kouvel-Fisher method, with values: β = 0.215, γ = 0.748, and δ = 4.489. With these values of the critical exponents, the isothermal magnetization M (μ0H) curves collapse below and above the Curie temperature (T C = 14 K) into two universal branches, fulfilling the single scaling equation m = f ± ( h ) , where m and h are the normalized magnetization and normalized magnetic field, respectively. The reliability of the critical exponents was confirmed by the Widom scaling hypothesis δ = 1 + γ / β , indicating that they are unambiguous and intrinsic to HoNi2 compound. This set of critical exponents lies between the theoretical values predicted by 3D and 2D models, suggesting a dimensional crossover between them. The primary reason for the nature of the determined critical behavior is linked to the tetrahedral local environment of Ni atoms within the unit cell.

ABSTRACT This paper explores the phase transitions between calamitic nematic ( N C ), biaxial nematic ( N B ) and discotic nematic ( N D ) phases in a mixture containing potassium laurate ( KL ), decanol ( DeOH ) , potassium sulphate ( K 2 SO 4 ) and water ( H 2 O ) . These transitions are studied using refractive indices and conoscopic images. The N C phase is uniaxial negative, while the N D phase is uniaxial positive, as expected. The biaxial nematic phases, both negative ( N B − negative) and positive ( N B + positive), are observed within the biaxial range and confirmed by conoscopic images. Temperature dependence of the symmetric invariant ( σ 2 ) of the order parameter is obtained from refractive index data in the biaxial nematic range. A transition from an N B − to an N B + configuration is determined at this point where the corresponding σ 2 reaches the maximum value. In this context, the micelle loses its predominant calamitic shape to acquire a predominant discotic shape.

ABSTRACT The structural, electronic, optical and thermodynamic properties of the halide perovskite material Cs2AgBiCl6 have been investigated using the density functional theory (DFT) method. As a first step, the structural properties of Cs2AgBiCl6 were examined to determine an optimized lattice constant, which was then used to calculate other physical properties. Analysis of the electronic band structure reveals that Cs2AgBiCl6 exhibits semiconductor characteristics. Optical properties, in particular the refractive index, have been investigated in the 1–3 eV energy range, corresponding to the bandgap region of the material. In addition, thermodynamic properties were analyzed using the quasi-harmonic Debye model over a temperature range of 0–600 K and a pressure range of 0–8 GPa. It was found that the Debye temperature decreases with increasing temperature but increases with increasing pressure.

ABSTRACT The structural stability, electronic structure, and optical properties of the novel Y x Gd1-x N ternary alloys were studied using the FP-LAPW method with the generalized gradient approximation + Hubbard U (GGA + U). Our results reveal that YxGd1-xN alloys can be experimentally synthesized because they exhibit energetic and mechanical stability. All these systems present semiconducting behavior. Both GdN and YN are indirect band gap semiconductors while YxGd1-xN alloys are direct band gap semiconductors for x = 0.25 , 0.5 , 0.75 because of hybridization between d (Y) and Gd(f) orbitals in the vicinity of the Fermi energy level. The f-d coupling induces the major magnetic moments on the Gd atom. The absorption spectra are reasonably high (>105 cm−1) and the bandgap energy and structure spacing match between YN and GaN which made Y x Gd1-x N alloys suitable for optoelectronic applications. In the absence of experimental work, our results can be useful for further studies.

ABSTRACT The combination of PbHfO3 and PbSnO3 in perovskite solid solutions presents valuable opportunities to study the formation mechanisms of incommensurate phases. Crystals of PbHf1-xSnxO3 with 8% Sn were grown and measured using broadband dielectric spectroscopy to investigate the nature of relaxation and the effects of phase transitions. Our findings reveal significant alterations in the dielectric response of the PbHf0.92Sn0.08O3 solid solution, shedding light on the influence of Sn doping on lattice dynamics during the phase transition.