Spinel zinc orthotitanate (Zn2TiO4) has attracted considerable attention as a promising semiconductor photocatalyst. Zn2TiO4and Zn1.85M0.15TiO4 (M = Cu2+, Ni2+, Co2+, and Mg2+) were synthesized via a two-step solid-state reactionmethod. Their structural, morphological, optical, and photocatalytic properties were systematically examined to evaluate the influence of metal-ion doping. XRD spectroscopy confirmed that all the prepared materials formed a cubic structure with the impurity of ZnO. The crystallite sizes of the prepared materials were in the nanometer range (40.41–45.65 nm). Morphological FESEM analysis revealed spherical-shaped particles, while EDS analysis confirmed the presence and homogeneous distribution of the constituent elements. HRTEM analysis further verified the crystalline nature of the materials through clear lattice fringes and corresponding d-spacing values. FTIR analysis confirmed the presence of functional groups associated with Zn-O and Ti-O bonding. The synthesized materials exhibited optical activity in the ultraviolet region. UV–Vis analysis demonstrated that metal-ion incorporation enhanced visible-light absorption and reduced the optical band gap energy from 3.22 eV for pristine Zn2TiO4 to 2.70 eV for Co-doped Zn2TiO4. Photoluminescence analysis indicated that doping influenced the recombination behavior of photogenerated charge carriers. The photocatalytic activity of the samples was tested using MB dye under UV irradiation. The highest degradation efficiency was 92.23%, and this was achieved for the sample Zn1.85Ni0.15TiO4, confirming that doped Zn2TiO4 is a promising photocatalyst for environmental remediation applications.
An RF-driven Josephson weak link can retain a measurable response maximum after that maximum ceases to identify the first Shapiro-step voltage. We reanalyse archived antenna-coupled YBCO measurements using a branch-paired, continuity-aware framework that separates symmetric voltage detuning from common-mode offset and permits an explicit non-identifiable outcome. The source archive comprises 181 TXT entries; the preserved analysis cohort contains 134 distinct RF-exposed records. At 155 GHz, Device A retains paired errors of 0.467–0.539% from 10 to 50 K, develops a 3.481% paired displacement at nominal 60 K, and yields no defensible first-step assignment in ten standard-frequency records at nominal 70 K despite persistent maxima. Device B remains identifiable at all 15 nominally matched temperature–frequency conditions and in 14/14 available nominal-70 K RF records (0.560% RMS error). Across 20 documented sensitivity settings, the broad condition-level interpretation is maintained, with two isolated false-positive acceptances under stress settings. A constrained overlapping-response reconstruction reproduces the displaced maximum, while fits to native acquired I–V samples also admit a flexible asymmetric single-response description; the microscopic decomposition is not identified. The results establish a practical distinction between detecting a maximum and assigning an identifiable Shapiro-step voltage, while documenting the uncertainty and configuration-comparison limits of the historical measurements.
The present article included organic light photodetectors (OPDs) based on Poly(vinyl alcohol) (PVA) supported with fluorescein (FLOs) and graphene nanosheets (GNs), and FLOs-supported PVA was fabricated and investigated. Two discs, one of FLOs/PVA (W) and the other of FLOs + GNs/PVA (G), each 2 um thick, were prepared by pouring the solution onto a clean Petri dish. Silver electrodes were deposited on them and used as photodetectors. It was found that adding of GNs shortened the rise and recovery times of the fabricated OPDs under visible-light illumination. The optical band gap [ Eg] decreases with FLs + GNs/PVA, ranging from 4.03 eV for FLs /PVA to 3.97 eV for FLs + GNs/PVA. The response was over a wide range of wavelengths (325–700 nm). with a −5V, 0 V and 5 V applied bias and 325–750 nm visible light illumination, the high responses of the W and G OPDs are 75.5 and 228.5, respectively . The quantum efficiency versus the luminous intensity of the two photodetectors indicated that of G OPDs is better than with W OPDs (EQE = 20–28% implies light intensity 25 mW/cm2 under measurement at a forward bias of 5 V). In addition, the other prepared material was used to study their thermometric measurements. FLOs/PVA and FLOs + GNs/PVA discs of 4 um thickness were prepared by the casting method. The thermal measurements of the discs were examined and compared with those of a pure PVA disc. It was observed that adding FLOs dye increased thermal conductivity, whereas adding GNs enhanced it.
In this work, a rigorous comparative first-principles investigation within the framework of density functional theory (DFT) is deployed to systematically quantify the phase-dependent electronic structure, directional optical tensors, and high-energy electron energy-loss profiles of Zirconium Dioxide (ZrO 2 ) polymorphs. Calculations were performed using the generalized gradient approximation parameterized by Perdew-Burke-Ernzerhof (GGA-PBE) as implemented in the CASTEP code, with a scissors operator applied to match experimental electronic baselines. Our quantitative data reveals that the isotropic cubic phase ZrO 2 possesses a direct band gap of 4.83 eV, whereas the symmetry-breaking distortion in the 7-fold coordinated monoclinic phase induces a transition to an indirect band gap of 5.17 eV. Partial density of states (PDOS) analysis indicates that the valence band maximum is dominated by localized O-2p states, while the conduction band minimum is governed by Zr-4d orbitals, confirming that the fundamental interband matrix elements are driven by p to d transitions. This structural symmetry reduction severely polarizes the macroscopic optical responses along the [100], [010], and [001] crystallographic directions. At the static limit (ῳ = 0 eV), the calculated diagonal dielectric tensor components for monoclinic phase diverge significantly (ε xx (0) = 4.63, ε yy (0) = 4.61, and ε zz (0) = 4.32), yielding a prominent static optical birefringence index of Δε = 0.31, contrasting with the degenerate isotropic response (ε = 4.91) of the cubic lattice. In the high-energy ultraviolet (UV) and deep-UV regimes, the frequency-dependent absorption coefficients, refractive indices, and optical conductivities reveal highly directional thresholds residing strictly within the solar-blind window (>4.0 eV). Furthermore, the electron energy loss function (EELS) resolves an intense, collective semi-core plasmon resonance localized at 37–38 eV, driven by deep transitions from the bound Zr-4p states into the conduction band continuum. These precise numerical benchmarks establish a definitive structure–property relationship governed by crystal field splitting and quantitatively validate the deployment of ZrO 2 films in polarization-sensitive optical components, solar-blind photodetectors, and high-energy radiation shielding barrier coatings.
