Phosphide Compounds Research Articles

First-principles investigation of electronic, structural, and magnetic properties of Si substituted cerium phosphide compounds CeSixP1-x

Cerium compounds have invited enough attention from scientists and researchers with respect to practical and fundamental implications having exotic physical, electronic, and magnetic properties like the kondo effect, anisotropic magnetic order, giant Hall effect and superconductivity. Hereby, we describe the mechanical stability and present the electronic, structural, and magnetic properties of new silicon-doped alloys of Cerium Phosphide with generic formula CeSixP1-x (x=0, 0.25, 0.5, 0.75 and 1.0) by using Wien2k code through DFT formalism. The simulation employs generalized gradient approximation through Perdew Bruke Ernzerhof with spin mode. The computed variables are lattice constants, volume, bulk modulus, pressure derivatives, and energy for structural studies. The partial and total densities of states and electronic energy band structures are calculated for electronic studies of these compounds. The magnetic properties of these compounds are described by computing spin magnetic moments. These doped alloys are predicated on being structurally stable, metallic, and non-magnetic materials.

Low‐Temperature Synthesis of Stable CaZn2P2 Zintl Phosphide Thin Films as Candidate Top Absorbers

AbstractThe development of tandem photovoltaics and photoelectrochemical solar cells requires new absorber materials with bandgaps in the range of ≈1.5–2.3 eV, for use in the top cell paired with a narrower‐gap bottom cell. An outstanding challenge is finding materials with suitable optoelectronic and defect properties, good operational stability, and synthesis conditions that preserve underlying device layers. This study demonstrates the Zintl phosphide compound CaZn2P2 as a compelling candidate semiconductor for these applications. Phase‐pure, ≈500 nm‐thick CaZn2P2 thin films are prepared using a scalable reactive sputter deposition process at growth temperatures as low as 100 °C, which is desirable for device integration. Ultraviolet‐visible spectroscopy shows that CaZn2P2 films exhibit an optical absorptivity of ≈104 cm−1 at ≈1.95 eV direct bandgap. Room‐temperature photoluminescence (PL) measurements show near‐band‐edge optical emission, and time‐resolved microwave conductivity (TRMC) measurements indicate a photoexcited carrier lifetime of ≈30 ns. CaZn2P2 is highly stable in both ambient conditions and moisture, as evidenced by PL and TRMC measurements. Experimental data are supported by first‐principles calculations, which indicate the absence of low‐formation‐energy, deep intrinsic defects. Overall, this study shall motivate future work integrating this potential top cell absorber material into tandem solar cells.

The influence of Gd content on the solidification and microstructure of AlSi7Mg0.3 casting alloy

The effects of Gd content on the solidification path and microstructure of an AlSi7Mg0.3 alloy have been studied. Two different Gd levels, 0.1 and 0.5 mass%, respectively, have been investigated while the material has been solidified at low (0.2 °C s−1) and high (1.3 °C s−1) cooling rates. Computer-aided thermal analysis and metallographic techniques have been used to study the solidification and microstructural evolution of the alloy at different Gd contents and cooling rates. The results show how Gd has no effect on the grain refinement at both cooling rates. The eutectic structure is unaffected at Gd level of 0.1 mass%. A concentration of 0.5 mass% Gd promotes the precipitation of the gadolinium phosphide (GdP) phase instead of aluminium phosphide (AlP) compounds, thus suppressing the eutectic plateau during the solidification and serving as nucleant for the GdAl2Si2 phase. The eutectic Si crystals solidified at low cooling rate are refined at 0.5 mass% Gd content, while the morphology of Si crystals is only partially modified at high cooling rate.

Lattice vibration, optical, and mechanical properties of aluminum phosphide (AlP) compound under the influence of temperature

Lattice vibration, optical, and mechanical properties of aluminum phosphide (AlP) compound under the influence of temperature

CLINICAL PROFILE OF PATIENTS WITH RODENTICIDE POISONING IN A TERTIARY CARE CENTER

Background: Poisoning is one of the leading cause for admission in emergency department and rodenticides are one of the major poisons used. It is highly toxic substance where morbidity and mortality are signicant. After Methods: obtaining informed consent 100 patients admitted with rodenticide poisoning in Department of General Medicine, Siddhartha medical college is enrolled into the study after fullling inclusion and exclusion criteria, data is collected and appropriate treatment is given. Out of 100 Results: patients included in the study, 55patients (55%) consumed zinc phosphide. 27patients(27%) consumed warfarin derivatives. 18patients(18%) consumed yellow phosphorous. Female preponderance(54%) was seen in this study. Poisoning is more common below 29years of age. Total of 77patients(77%) recovered without complications, most common symptom is vomiting and complication is acute hepatitis(23%). Conclusion: This study shows Yellow phosphorous has the worst outcome. Zinc phosphide is the most common poison consumed and low mortality is seen in zinc phosphide and warfarin compounds

Nanoarchitectonics with the amorphous rhenium phosphide compounds for enhanced catalytic activity of hydrogen evolution reaction

Rhenium can be used as a highly active electrocatalyst for the hydrogen evolution reaction (HER) owing to its theoretically large exchange current and optimum binding energy in the Sabatier plot. However, as rhenium metal cannot achieve a high performance owing to few active sites, rhenium must be transmuted to modulate its catalytic activity. In this study, we first fabricated an amorphous rhenium phosphide/carbon composite as an electrocatalyst for the HER using a simple annealing process. The obtained amorphous rhenium phosphide acts as an efficient HER electrocatalyst with an overpotential of 79.1 mV at a current density of 10 mA cm−2 in 0.5 M H2SO4 and the corresponding Tafel slope of 55 mV dec−1, thereby outperforming the crystalline phase with the overpotential and Tafel slope of 109 mV and 67 mV dec−1, respectively. The 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) precursor has a strong ability to chelate metal ions and provides a phosphorus source to prepare rhenium phosphide. The phosphorization of rhenium metal leads to enhanced catalytic activity, providing abundant and efficient active sites for catalysis. These amorphous species might be beneficial for HER because of their disordered atomic arrangement and abundant defect sites, indicating a higher catalytic activity than that of the crystalline phase.

Coincident Nodal Line and Nodal Surface Phonon States in Ternary Phosphide Compound BaLiP

With the continuous development of topological properties in condensed matter systems, the current research focus has been expanded into phononic bosonic states. Compared with the conventional electronic fermions, topological phonons exhibit very distinct features. In this study, based on density functional calculations, we have systematically investigated the topological phonons in the ternary phosphide compound BaLiP. Coincident nodal line and nodal surface states are revealed in the middle part of the phononic spectrum and they are formed by the same two phonon bands. Detailed band structure mechanism and symmetry operation formalism are provided. More importantly, evident surface states are observed from the entire nodal line and they are all well separated from the bulk state projection, very beneficial and preferable for future experimental investigation. Lastly, the mechanical properties are also examined and several important parameters are provided, which can be very useful for the practical application. Considering the multiple advantages of the topological nodal states in this material, the corresponding experimental study can be immediately inspired.

Revealing the structure and physical properties of Ba-based phosphide compounds: A theoretical study

Nitride and phosphide semiconductors AB2X2 (A = Ca, Sr; B = Zn, Cd; X = N, P) are the promising novel materials for optoelectronic applications. A comparative study is performed to reveal the stability, mechanical, electronic, and optical properties of Ba-based phosphide compounds. Our results indicate that it should have three stable structures (α, β, and γ phases) for BaZn2P2, while it only exists a γ phase for BaMg2P2 and BaCd2P2. This finding is reasonable consistent with the experimental results. Moreover, the dynamical, thermal, and mechanical stability of γ-BaZn2P2 and γ-Ba(Zn0.5Cd0.5)2P2 are verified. Three different phases of BaZn2P2 display completely different electronic features. The compound β-BaZn2P2 has a narrower band gap than those of α and γ analogues. An indirect to direct band gap transition is revealed for Ba(Zn/Cd)2P2 alloys. The γ-BaZn2P2 has an indirect band gap of 1.22 eV, while γ-Ba(Zn0.5Cd0.5)2P2 and γ-BaCd2P2 show direct band gaps of 1.27 and 1.40 eV. The optical properties of these compounds are discussed in detail. Our study finds that γ-Ba(Zn0.5Cd0.5)2P2 is a less-toxic, stable, and ductile material, and it also shows excellent optoelectronic properties including suitable direct band gap and strong optical absorption.

Multiphase nanosheet-nanowire cerium oxide and nickel-cobalt phosphide for highly-efficient electrocatalytic overall water splitting

Herein, a hybrid nanowire-nanosheet structure made of the cerium oxide and nickel-cobalt phosphide (CeO2-NiCoPx) compound is in situ engineered on the Ni-Co foam (CeO2-NiCoPx/NCF) for the robust water splitting (HER and OER), and the overpotentials of synthesized CeO2-NiCoPx/NCF are about 39 mV for HER and 260 mV for OER at a current density of 10 mA cm−2 (j10). Meanwhile, the nanostructure of CeO2-NiCoPx is well preserved after a long-term electrocatalytic process (100 h) at a large current density of 100 mA cm−2 (j100). When the CeO2-NiCoPx/NCF simultaneously acts as the HER and OER electrodes, the potential of 1.49 V is obtained for transferring j10 with an excellent durability. Theoretical simulations and in operando Raman spectroscopy reveal that the Co and Ni atoms for CeO2-NiCoPx/NCF catalyst are likely to act as the pivotal reaction centers for HER and OER processes, respectively.

DFT Study of ScP and AlP in B1, B2, and B3 Phases at Ambient Pressure

Structural, electronic, elastic, and dynamic characteristics of scandium phosphide and aluminium phosphide compounds are studied theoretically. The study has been performed for rock salt (B1), CsCl (B2), and zinc blend (B3). We use the density functional theory, which is based on the plane wave basis and the pseudopotential approach, as implemented in the Quantum Espresso Software package. ScP and AlP exhibits metallic behavior in the B1 and B2 phases. The B3 phase of ScP displays a semiconductor characteristic with a broad and straight band gap at X of (1.617). In AlP, the B3 phase exhibits semiconductor characteristics with an indirect band gap at Г-X of (1.60). Both compounds ScP and AlP on B1, B2, and B3 structures report computed ground state parameters. The zinc blend phase is the most stable of the three phases, according to the findings. Our computed results are in good agreement with earlier investigations. The work presented in this article is related to sustainable development goals (SDGs) to transform our world regarding industry, innovation, and infrastructure.

Phase-Selective Synthesis of Ruthenium Phosphide in Hybrid Structure Enables Efficient Hybrid Water Electrolysis Under pH-Universal Conditions.

Hydrazine-assisted hybrid water electrolysis is an energy-saving approach to produce high-purity hydrogen, whereas the development of pH-universal bifunctional catalysts encounters a grand challenge. Herein, a phase-selective synthesis of ruthenium phosphide compounds hybrid with carbon forming pancake-like particles (denoted as Rux P/C-PAN, x= 1 or 2) is presented. The obtained RuP/C-PAN exhibits the highest catalytic activity among the control samples, delivering ultralow cell voltages of 0.03, 0.27, and 0.65V to drive 10mAcm-2 using hybrid water electrolysis corresponding to pH values of 14, 7, and 0, respectively. Theoretical calculation deciphers that the RuP phase displays optimized free energy for hydrogen adsorption and reduced energy barrier for hydrazine dehydrogenation. This work may not only open up a new avenue in exploring universally compatible catalyst to transcend the limitation on the pH value of electrolytes, but also push forward the development of an energy-saving hydrogen generation technique based on emerging hybrid water electrolysis.

Revealing the stability and optoelectronic properties of novel nitride and phosphide semiconductors: A DFT prediction

Nitride semiconductors have attracted considerable attention in recent years. CaZn2N2 and SrZn2N2 are the promising materials for optoelectronic applications. In order to explore more novel semiconductors, a detailed theoretical study has been performed to investigate the structural, electronic, and optical properties of AB2×2 (A = Ca, Sr, Ba; B = Mg, Zn, Cd; X = N, P) and their alloys. The calculated band gaps of nitride compounds with the HSE06 functional are consistent well with the reported experimental values. Most compounds are direct bandgap semiconductors and they show tunable band gaps. Nine compounds show suitable direct band gaps with the values of 1.4–1.8 eV. In addition, the stability of four alloying compounds is confirmed by different theoretical methods. Moreover, these phosphide compounds and their alloys also show good carrier mobility. Importantly, Sr(Zn0.5Cd0.5)2P2 contains less toxic Cd element, and it has an ideal band gap of 1.38 eV and high absorption coefficient, which is the most promising material for optoelectronic applications. The present study has indicated the potential suitability of phosphide semiconductors for solar cell applications.

Simulation of double-junction III-phosphides/silicon solar cells

The characteristics of two-junction solar cells were calculated in this work, in which phosphides of group III are used as the top junction, and Si as the bottom junction. The following ternary phosphide compounds Ga0.52In0.48P (1.85 eV), GaPN0.02 (1.9 eV), and GaPN0.04 (1.7 eV) were considered as the active material of the top junction. The use of GaPN0.04 allowed one to reach the current matching with the bottom Si junction and an efficiency of 30% was achieved. In addition, the influence of the layer thickness, the lifetime of minority charge carriers and the electronic affinity on the efficiency of solar energy conversion were considered.

Interfacial microstructure and strength of brazed copper/porous copper foam towards the effect of porous copper foam pore density and brazing holding time

AbstractThe porous copper foam was sandwiched between two coppers plate and then brazed using copper‐tin (9.7 %)‐nickel (5.7 %)‐phosphorus (7 %) filler foil. Brazing process was conducted to joint copper/porous copper foam by evaluating the effect of porous copper foam pore densities [pore per inch (PPI)] and brazing holding times. The brazed joint interface of copper and porous copper foam was characterised using Field emission scanning electron microscopy and Energy‐dispersive x‐ray spectroscopy for the microstructure and elemental composition analysis, respectively. X‐ray diffraction analysis was carried out on the shear fractured surfaces of brazed copper and porous copper foam for phase determination. The results exhibited distinct phases of copper (Cu), copper phosphide (Cu3P), nickel phosphide (Ni3P), and copper compound with tin (6 : 5) (Cu6Sn5). The filler layer was formed as an island‐shaped that consists of copper phosphide and nickel phosphide. Prolong brazing holding time causes a thinner filler layer in brazing seam. While the non‐uniform thickness of the filler layer was observed at different pore densities of porous copper foam. The shear strength of brazed copper/porous copper foam 15 PPI with a 10 min brazing holding time yield a maximum shear strength of 2.9 MPa.

PREDICTORS OF MORTALITY IN ACUTELY INTOXICATED PATIENTS ADMITTED TO INTENSIVE CARE UNIT IN MENOUFIA UNIVERSITY HOSPITAL

Background: Acute poisoning is a major cause of suicide and public health problem all over the world. Evaluation of the morbidity and outcome of admitted patients can assess the efficacy of treatment, making it possible to take better decisions and to further improve quality of care. Objectives: The present study was aimed to study multiple factors associated with fatal poisoning of the patients admitted to ICU and to assess APACHE II Scoring System in prediction of poisoning outcome. Material and Methods: in this prospective study, from January 2019 to December 2019, critical patients with acute poisoning admitted to ICU, Menoufia University hospitals-Egypt were enrolled into this study. Data including demographic features, clinical and lab findings, Acute Physiology and Chronic Health Evaluation (APACHE II) at admission, mode and route of poisoning, the need for mechanical ventilation or vasoactive agents, duration of mechanical ventilation and ICU stay were documented, collected and analyzed by the relevant statistical methods. All patients were studied till death or discharge from the ICU. Results: During the study period, 152 out of 1745 patients admitted to the Menoufia poisoning control center (MPCC) were admitted to the ICU. Out of them, 54 died and 98 survived. The majority were in age group (20-40) years. Females were (62.5%) of the total cases. Intentional poisoning was predominant. Pesticides were the most commonly employed poison including aluminium phosphide and organophosphorus compounds. Aluminium phosphide was highly toxic. High APACHE II score, mechanical ventilation and inotropic support were associated with high mortality. Conclusion: Some findings were correlated with outcome in acute poisoning and can be used as guidance for risk assessment and treatment planning of the patients. The higher the APACHE II score, the more serious the condition becomes. Proper counseling to counteract the stressful situations to reduce fatalities. In addition, some policy should be applied to control the easy availability of poisons in the society.

Crystal Structure and Properties of Layered Pnictides BaCuSi2Pn3 (Pn = P, As).

Two novel layered compounds BaCuSi2Pn3 (Pn = P, As) adopting new structure types are reported. As revealed by single-crystal X-ray diffraction, both compounds are composed of unique Cu-Si-Pn layers featuring CuPn3 and Si2Pn6 structural motifs found in other archetypal pnictide materials. The stacking of the isostructural Cu-Si-Pn layers is different for phosphide and arsenide compounds. Synthesis from elements aided by in situ synchrotron powder X-ray diffraction resulted in the obtainment of bulk powders with a minimized amount of admixtures. Experimentally measured physical properties of BaCuSi2As3 unexpectedly showed metal-like behavior at temperatures above 15 K, despite the fact that density functional theory calculations predict a small band gap of 0.4 eV. BaCuSi2As3 exhibits ultralow thermal conductivity, which can be explained by the combination of a layered crystal structure with alternating covalent and ionic bonding, which feature rattling of Cu atoms similar to that in tetrahedrites.

Structural and elastic properties, Vickers hardness and Debye temperature of (B1) BP: DFT study

A theoretical study of the structural parameters and elastic constants of boron phosphide (BP) compound with cubic rocksalt structure has been carried out using ab-initio density functional theory (DFT) and density functional perturbation theory (DFPT) calculations based on the plane-wave and pseudopotential (PW-PP) approach. Elastic anisotropy factors, Cauchy pressure, inverted Pugh’s ratio, aggregate mechanical moduli (shear modulus, Young's modulus and Poisson's ratio), Vickers hardness HV, elastic wave velocity as well as the Debye temperature θD and the melting point have been also calculated. Our obtained results are in general in good agreement with other data of the literature. The deviation between our obtained value (4.225 Ã…) of the lattice constant and the theoretical value (4.282 Ã…) of the literature is around 1.33%, while that between our obtained value (169.7 GPa) of the bulk modulus and the theoretical one (171 GPa) is only around 0.77%. The calculated values of HV and θD were found at around 30.5 GPa and 1254 K (1314.4 K), respectively. Â

Porous Ni5P4 as a promising cocatalyst for boosting the photocatalytic hydrogen evolution reaction performance

Nonmetallic cocatalysts have demonstrated unprecedented potential for accelerating photocatalytic hydrogen evolution reaction (HER). In this study, a nickel phosphide compound, namely Ni5P4, with porous carnation-like superstructure has been target-synthesized and then employed as HER cocatalyst to in-situ build a hybrid with protonated g-C3N4 nanosheets via an electrostatic self-assembly method. Owing to the synergistic advantages of the excellent metallic conductivity and porous carnation-like superstructure of Ni5P4, the as-obtained HCN/Ni5P4 Schottky-junction with abundant active sites, low H* atom adsorption energy and efficient charge carrier transport channel, affords the photocatalytic H2 production rate of 1157.5 μmol g−1 h−1 when exposed to visible light (λ > 420 nm). This photocatalytic H2 production rate was much higher than those of the corresponding reference cocatalysts, namely Ni2P and NiS2 (169.1 and 593.1 μmol g−1 h−1, respectively), both of which were derived from the same Ni(OH)2 precursor. This study provides a new idea for the design of highly active noble-metal-free materials for the photocatalytic HER.

Nano-Structured Transition Metal Phosphides As an Efficient Electrocatalysts for Oxygen Evolution Reaction

Although the catalytic activity of transition metal phosphide compounds, such as dinickel phosphide (Ni2P), have been known for over half a century. they have only recently been investigated for heterogeneous (electro)catalysis. In 1995, it was shown that the performance of electrodeposited amorphous Ni–P electrodes (ca. 3 wt% phosphorous content) toward the HER in alkaline conditions can be orders of magnitude higher than that of Ni electrodes [1]. Detailed structural analysis of these transition metal phosphide materials had not been discussed in such early works. it was only very recently realized that the transition metal phosphides have reemerged as one of the most promising classes of earth-abundant inorganic electrocatalysts.Depending on the P:Ni molar ratio and the reaction temperature, different phases have been reported for Ni-phosphide compounds. Among all NixPy phases, Ni12P5 nanoparticles shows high electrocatalytical activity toward OER due to its unique crystallite structure and the higher concentration of nickel in this phase. which enables the formation of an amorphous NiOOH/Ni(OH)2 shell on a modified multiphase with a disordered phosphide/phosphite core [2]. However, the synthesis of Ni12P5 is quite challenging and a small deviation in the P:Ni molar ratio will result in Ni2P phase.In this study, pure phase of Ni12P5 and Ni0.9Fe0.1P colloidal nanoparticles have been synthesized by the reaction of [Ni(acac)2] with oleylamine (OA) and trioctylphosphine (TOP) reactants. OA is the reducing agent and thus controls the nucleation rate and TOP acts a source of phosphorus and also provides surface stabilization for tuning particles size. This synthesis results in monodisperse nanoparticles of diameter approximately 12nm [3]. These Ni12P5 and Ni0.9Fe0.1P nanoparticles show enhanced electrocatalytical activity toward OER in 0.1M KOH electrolyte, resulting in a current density of 10 mA cm−2 with overpotentials at 0.304 V and 0.20 V respectively.

Bimetallic Ni‒Co phosphide nanosheets self-supported on nickel foam as high-performance electrocatalyst for hydrogen evolution reaction

In this work, bimetallic nickel-cobalt phosphide (Ni-Co-P/NF) self-supported on nickel foam (NF) is synthesized for hydrogen evolution reaction (HER). A two-step method of electrodeposition with subsequently low-temperature phosphatizing is adopted. The physicochemical characterizations of the as-prepared Ni-Co-P/NF show that the surface is covered by metallic phosphide compounds (NiCoP, NiP and Co2P) with unique morphology, consisted of nanosheets randomly dispersed on villiform 3D integrated framework. The electrochemical characterizations demonstrate that Ni-Co-P/NF exhibits the highest performance for HER, in 1.0 M KOH aqueous solution, compared to other as-prepared electrocatalysts. Specifically, it requires very low overpotential values of 85, 210 and 350 mV for delivering large current densities of −10, −500 and −1,500 mA cm−2, respectively, revealing a low Tafel slope of 46 mV dec−1. Besides, Ni-Co-P/NF also displays long-term durability lasting 24 h without obvious deactivation. This work highlights that the NiCoP, NiP and Co2P active phases play a crucial role for the good HER activity. In addition, the unique morphology with self-supported structure provides large electrochemical surface area, allowing the exposure of higher amount of active sites for HER. These self-supported electrocatalysts, without binder, could also improve the electrode's HER activity and stability. This work, therefore, provides a controllable and feasible strategy to synthesize bimetallic phosphides of unique morphology with high HER activity.