In this paper, we identify three possible candidate series of half-metals (HM) from Bi-based double perovskites Bi₂BB′O₆ (BB′ = transition metal ions) through calculations utilizing the density functional theory (DFT) and full-structural optimization, in which the generalized gradient approximation (GGA) and the strong correlation effect (GGA + U) are considered. After observing the candidate materials under four types of magnetic states, i.e., ferromagnetic (FM), ferrimagnetic (FiM), antiferromagnetic (AF), and nonmagnetic (NM), we found eight promising candidates for half-metallic materials. Under the GGA scheme, there are three ferromagnetic-half-metal (FM-HM) materials, Bi₂CrCoO₆, Bi₂CrNiO₆ and Bi₂FeNiO₆, and three FiM-HM materials, Bi₂FeZnO₆, Bi₂CrZnO₆ and Bi₂CoZnO₆. With implementation of the Coulomb interaction correction (GGA + U), we find two stable half-metallic materials: Bi₂CrNiO₆ and Bi₂CrZnO₆. We determine that the stability of some of these materials are tied to the double exchange interaction, an indirect interaction within the higher powers of localized spin interaction among transition metals via oxygen ions. Found in half-metallic materials, and especially those in the ferromagnetic (FM) state, the double exchange interaction is recognized in the FM-HM materials Bi₂CrCoO₆ and Bi₂FeNiO₆.

The glucose concentration in human blood can have a worrisome impact on human health, so the distribution of blood glucose contaminants in the human body is an important indicator that can be used to monitor diabetes. Diabetes affects many parts of the human body, such as neurological impairment, erectile dysfunction, and hardening of the arteries resulting in organ loss. In this study, cyclic voltammetry (CV) was used to process the electrical properties of a solution by preparing electrodes with CuO nanoparticles modified ZnO tetrapod nanostructures deposited on fluorine-doped tin oxide glass (CuO/ZnO/FTO). The measurements were processed in glucose solutions of different concentrations purposing for developing the sensitivity of the sensor. Different immersion times in the precursor copper sulfate solution were also used for preparing the electrode and carried out for electrochemical studies to adjust the electrode capability. The modified electrode, which was immersed in copper sulfate for 30 s, was efficient in detecting glucose molecules in different concentrations at the potential of +0.6 V. The rising slope is strongly and positively correlated with the concentration of glucose. One of the significant results is the indication that glucose concentration is linearly proportional to the current value of CV. After the measurement test with the addition of interference, the sensor can still identify the glucose concentration in the solution without being affected. This result proves that the sensor has considerable potential for developing into a high-performance non-enzymatic glucose sensor.

Pb-based double perovskite compounds with chemical formula Phey have abundant physical properties in the spintronic field. Among all the features, the spin interaction of half-metallic (HM) is regarded as an important performance measure because of its high potential in spintronic devices. In this research study, we calculate density of state (DOS) to investigate possible half-metal candidates by executing structural optimization based on the method of generalized gradient approximation (GGA) and strong correlation effect (GGA + U). Furthermore, following the earlier methods by calculating and comparing energy difference of various compounds with the four initial magnetic states: ferromagnetic, ferrimagnetic, antiferromagnetic and nonmagnetic, we can determine which magnetic state is more stable. Results indicate that there are 13 possible ferrimagnetic HM candidates in these combinations, including Pb₂NbTcO₆, Pb₂TaTcO₆, Pb₂TiRuO₆, Pb₂ZrRuO₆, Pb₂HfRuO₆, Pb₂VRuO₆, Pb₂NbRuO₆, Pb₂TadRuO₆, Pb₂ZrOsO₆, Pb₂HfOsO₆, Pb₂VOsO₆, Pb₂ZrRhO₆ and Pb₂HfRhO₆ under GGA and GGA + U schemes. The stability of analysis by analyzing the energy gap illustrates that all 13 possible candidates are half metals and ferrimagnetic states, so our studies could provide guidelines for scientists to fabricate new double perovskites in future.

The widely discussed result of derivation for the Casimir temperature has been published by the authors of this paper. Recently we noticed that the unsolved problem of Navier–Stokes equation’s existence and the smoothness can be thought by the idea of the globular protein (Einstein’s colloidal particles (1905)) placed in liquid 3He at the Casimir temperature. Although the globular protein is not dissolved in liquid 3He and is as the cusp but it is exactly due to such nature of cusp in liquid 3He, leads to an interesting phenomenon if it is differentiable in the Navier–Stokes equation in a peculiar case, one can understand the existence and the smoothness are established as to a promising candidate answer.

We predict new class of three-dimensional (3D) Z2 topological insulators (TIs) in A2BiAtO6 (A=Ba, Ca and Sr) double perovskites with band gaps due to spin-orbital couplings (SOC). By employing first-principle calculations based on the density functional theory (DFT), we obtain energy gaps of 0.70 , 0.71 and 0.72 eV for A2BiAtO6 with A=Ba, Ca and Sr, respectively. These energy band gaps are among the largest ever found so far and allow for potential room-temperature applications of their topological properties. The proposed materials are not only chemically more inert but also more robust against surface perturbations due to its intrinsic protection layer.