Phosphorus Precursor Research Articles

DIP-COATING SENYAWA KALSIUM FOSFAT DARI BATU KAPUR BUKIT TUI DENGAN VARIASI RATIO MOL Ca/P MELALUI METODE SOL-GEL

Preparation of Dip-Coating Calcium Phosphate via sol-gel method using natural limestone Bukit Tui as calcium precursors and diammonium hydrogen phosphate as phosphorus precursors with various Ca/P mol ratio has been investigated. Etanol was used as solvent and DEA (dietanolamine) as stabilizing agent. Powder were prepared by calcinated the sol at 950 o C. The results characterized by Fourier Transform Infra-red, X-Ray diffraction and Scanning Electron Microscopy. FTIR results showed that the vibration form was PO 4 3- , P 2 O 7 4- , O-H and CO 2 . X-Ray Diffraction (XRD) patterns of powder with various Ca/P mol ratio showed that the product of calcium phosphate was Ca 2 P 2 O 7 and also found the hydroxyapatite Ca 10 (PO 4 ) 6 (0H) 2 in Ca/P ratio mol 1,7. Scanning Electron Microscopy (SEM) images of powder calcium phosphate revealed that their morphology were spheric and homogen. The coating process was done at glass substrate with coating speed 20 cm/min by calcinations at 400 o C. . X-Ray Diffraction (XRD) patterns of thin layer showed that the product was Ca 2 P 2 O 7 and Scanning Electron Microscopy (SEM) images of thin layer revealed that their morphology were bulk. Key words; natural limestone, calcium phosphate, hydroxyapatite, sol-gel, dip-coating

Study of Eu3+ and Tm3+ substitution effects in sol–gel fabricated calcium hydroxyapatite

In this study, an aqueous sol–gel chemistry route based on phosphoric acid as the phosphorus precursor, calcium acetate monohydrate and lanthanide (III) oxides as source of calcium and lanthanide ions, respectively, have been used to prepare europium- and thulium-substituted calcium hydroxyapatite (CHAp:Ln3+) powders. The ethylenediaminetetraacetic acid was used as complexing agent in the sol–gel processing. The final products were obtained by calcination of the dry precursor gels for 5 h at 1000 °C. The phase transformations, composition, and structural changes in the polycrystalline samples were studied by infrared spectroscopy, X-ray powder diffraction analysis, scanning electron microscopy and photoluminescence measurements. It was demonstrated, however, that the substitution of calcium by Eu or Tm proceeds in the CHAp at low concentration of lanthanide ion. Excitation and emission of Tm3+ in CHAp:Tm3+ spectra.

Resolving the Chemistry of Zn3P2 Nanocrystal Growth

[EtZnP(SiMe3)2]3 has been identified as a competent intermediate for the growth of stoichiometric α-Zn3P2 nanocrystals from Zn-rich zinc phosphide seeds as determined by powder X-ray diffraction, solid-state nuclear magnetic resonance (NMR) spectroscopy, and transmission electron microscopy analysis. Solution-phase NMR data show that this trimer forms in situ upon reaction of P(SiMe3)3 and ZnEt2 in the presence of Zn(O2CR)2 under zinc carboxylate-limited conditions. [EtZnP(SiMe3)2]3 can also be used to nucleate zinc phosphide; however, in comparison to a previously examined nucleation pathway involving (Et2Zn)P(ZnO2CR)2(SiMe3), a decrease in relative reactivity leads to fewer nuclei and larger, more crystalline particles. These data, in combination with previous literature on the synthesis of zinc phosphide nanocrystals, were then aggregated to propose a set of design principles for the synthesis of zinc phosphide nanocrystals using P(SiMe3)3 as the phosphorus precursor.

Monolayer Doping of Silicon through Grafting a Tailored Molecular Phosphorus Precursor onto Oxide-Passivated Silicon Surfaces

Monolayer doping (MLD) of silicon substrates at the nanoscale is a powerful method to provide controlled doses of dopants and defect-free materials. However, this approach requires the deposition of a thick SiO2 cap layer to limit dopant evaporation during annealing. Here, we describe the controlled surface doping of thin oxide-passivated silicon wafers through a two-step process involving the grafting of a molecular phosphorus precursor containing a polyhedral oligomeric silsesquioxane (POSS) scaffold with silica-like architecture and thermal annealing. We show that the POSS scaffold favors the controlled formation of dopant-containing surface species with up to ∼8 × 1013 P atoms cm–2 and efficiently avoids phosphorus evaporation during annealing for temperatures up to 800 °C. Silicon doping is demonstrated, in particular, by grafting the POSS phosphorus triester on SiO2/Si wafers with optimized surface preparation (thin SiO2 layer of 0.7 nm) and annealing temperature (1000 °C), which provides phosphorus...

Sol–gel synthesis, phase composition, morphological and structural characterization of Ca10(PO4)6(OH)2: XRD, FTIR, SEM, 3D SEM and solid-state NMR studies

Aqueous sol–gel chemistry route based on ammonium–hydrogen phosphate as the phosphorus precursor, calcium acetate monohydrate as source of calcium ions, and 1,2-ethylendiaminetetraacetic acid (EDTA), or 1,2-diaminocyclohexanetetracetic acid (DCTA), or tartaric acid (TA), or ethylene glycol (EG), or glycerol (GL) as complexing agents have been used to prepare calcium hydroxyapatite (Ca10(PO4)6(OH)2, CHAp). The phase transformations, composition, and structural changes in the polycrystalline samples were studied by infrared spectroscopy (FTIR), X-ray powder diffraction analysis (XRD), and scanning electron microscopy (SEM). The local short-range (nano- and mezo-) scale effects in CHAp were studied using solid-state NMR spectroscopy. The spatial 3D data from the SEM images of CHAp samples obtained by TA, EG and GL sol–gel routes were recovered for the first time to our knowledge.

Halide-Amine Co-Passivated Indium Phosphide Colloidal Quantum Dots in Tetrahedral Shape.

Wet chemical synthesis of covalent III-V colloidal quantum dots (CQDs) has been challenging because of uncontrolled surfaces and a poor understanding of surface-ligand interactions. We report a simple acid-free approach to synthesize highly crystalline indium phosphide CQDs in the unique tetrahedral shape by using tris(dimethylamino) phosphine and indium trichloride as the phosphorus and indium precursors, dissolved in oleylamine. Our chemical analyses indicate that both the oleylamine and chloride ligands participate in the stabilization of tetrahedral-shaped InP CQDs covered with cation-rich (111) facets. Based on density functional theory calculations, we propose that fractional dangling electrons of the In-rich (111) surface could be completely passivated by three halide and one primary amine ligands per the (2×2) surface unit, satisfying the 8-electron rule. This halide-amine co-passivation strategy will benefit the synthesis of stable III-V CQDs with controlled surfaces.

Halide–Amine Co‐Passivated Indium Phosphide Colloidal Quantum Dots in Tetrahedral Shape

AbstractWet chemical synthesis of covalent III‐V colloidal quantum dots (CQDs) has been challenging because of uncontrolled surfaces and a poor understanding of surface–ligand interactions. We report a simple acid‐free approach to synthesize highly crystalline indium phosphide CQDs in the unique tetrahedral shape by using tris(dimethylamino) phosphine and indium trichloride as the phosphorus and indium precursors, dissolved in oleylamine. Our chemical analyses indicate that both the oleylamine and chloride ligands participate in the stabilization of tetrahedral‐shaped InP CQDs covered with cation‐rich (111) facets. Based on density functional theory calculations, we propose that fractional dangling electrons of the In‐rich (111) surface could be completely passivated by three halide and one primary amine ligands per the (2×2) surface unit, satisfying the 8‐electron rule. This halide–amine co‐passivation strategy will benefit the synthesis of stable III‐V CQDs with controlled surfaces.

Direct Observation of Early-Stage Quantum Dot Growth Mechanisms with High-Temperature Ab Initio Molecular Dynamics

Colloidal quantum dots (QDs) exhibit highly desirable size- and shape-dependent properties for applications from electronic devices to imaging. Indium phosphide QDs have emerged as a primary candidate to replace the more toxic CdSe QDs, but production of InP QDs with the desired properties lags behind other QD materials due to a poor understanding of how to tune the growth process. Using high-temperature ab initio molecular dynamics (AIMD) simulations, we report the first direct observation of the early stage intermediates and subsequent formation of an InP cluster from separated indium and phosphorus precursors. In our simulations, indium agglomeration precedes formation of In-P bonds. We observe a predominantly intercomplex pathway in which In-P bonds form between one set of precursor copies while the carboxylate ligand of a second indium precursor in the agglomerated indium abstracts a ligand from the phosphorus precursor. This process produces an indium-rich cluster with structural properties comparable to those in bulk zinc-blende InP crystals. Minimum energy pathway characterization of the AIMD-sampled reaction events confirms these observations and identifies that In-carboxylate dissociation energetics solely determine the barrier along the In-P bond formation pathway, which is lower for intercomplex (13 kcal/mol) than intracomplex (21 kcal/mol) mechanisms. The phosphorus precursor chemistry, on the other hand, controls the thermodynamics of the reaction. Our observations of the differing roles of precursors in controlling QD formation strongly suggests that the challenges thus far encountered in InP QD synthesis optimization may be attributed to an overlooked need for a cooperative tuning strategy that simultaneously addresses the chemistry of both indium and phosphorus precursors.

Improving the ensemble optical properties of InP quantum dots by indium precursor modification

Indium phosphide quantum dots typically exhibit broad and poorly defined ensemble optical properties due to a highly pronounced nucleation period that consumes virtually all phosphorus precursors, leading to subsequent growth by Ostwald ripening and poor final size distributions. Previous attempts to reduce the reactivity of the phosphorus precursor, and thereby limit its consumption during the nucleation phase, have not led to appreciably better optical properties due to an unwanted increase in the duration of nucleation. Here we present an alternative approach to reducing initial precursor consumption using a simple modification of the indium precursor, in which the widely used carboxylate ligand is replaced by a phosphine. The change of ligand leaves residual precursor available for size-focusing growth after nucleation, leading to significantly improved spectral features. Band-edge emission peaks are typically 30% narrower than for the standard method.

Effect of precursor on the catalytic properties of Ni2P/SiO2 in methyl palmitate hydrodeoxygenation

The effect of phosphorus precursor on the physicochemical and catalytic properties of silica-supported nickel phosphide catalysts in the hydrodeoxygenation (HDO) of aliphatic model compound methyl palmitate (C15H31COOCH3) has been considered.

Simple synthesis and characterization of nickel phosphide nanostructures assisted by different inorganic precursors

Nickel phosphide nanostructures were prepared by thermal decomposition method from different inorganic precursors, such as: bis(salicylidene)nickel(II) [Ni(sal)2], bis(salicylate)nickel(II) [Ni(Hsal)2], nickel oxalate [Ni(O4C2)(H2O)4] and nickel-o-phthalate [Ni(pht)(H2O)2]. Nickel(II) acetate tetrahydrate Ni(CH3COO)2·4H2O was used as reference. Nanostructural control of products prepared through the thermolysis of precursors using triphenylphosphine as a surfactant solvent and phosphorus precursor was reported. The SEM and TEM images show the morphology and particle size of the as-synthesized nanostructures. The XRD patterns show mixed-phase hexagonal Ni2P/tetragonal Ni12P5 (represented as NixPy). The FT-IR spectroscopy confirms that the products prepared are NixPy phase, which is in agreement with XRD results.

Synthesis of Co2P/Co nanocomposites using single source precursor by thermal decomposition method

In this article, the synthesis and characterization of Co2P/Co nanocomposites are reported. Three kinds of precursors are studied: bis(salicylidene)cobalt(II) [Co(sal)2], bis(salicylate)cobalt(II) [Co(Hsal)2] and cobalt oxalate [Co(O4C2)·4H2O]. The cobalt(II) acetate tetrahydrate Co(CH3COO)2·4H2O is used as reference. The nanocomposites are prepared by thermal decomposition method using triphenylphosphine as a surfactant solvent and phosphorus precursor. A possible mechanism of the formation of the nanocomposites is put forward to explain the experimental observations. This is the first time that Co2P/Co nanocomposites are synthesized. To study the crystalline structure, composition, size, morphology and magnetic property of the products, characterization techniques including XRD, SEM, TEM, FT-IR and VSM are employed.

Atomic Layer Deposition of Lithium Phosphorus Oxynitride

An atomic layer deposition (ALD) process is successfully developed for fabricating high-quality lithium phosphorus oxynitride (LiPON) thin films for a potential use as a conformal solid-state electrolyte coating in 3D Li-ion microbattery technology. In our ALD process the challenge of simultaneously incorporating phosphorus and nitrogen in the films is overcome by using a novel nitrogen-containing phosphorus precursor, diethyl phosphoramidate, together with lithium hexamethyldisilazide as the lithium precursor. A temperature window is found around 270–310 °C, where homogeneous films are realized and the film growth is controlled in a digital manner by the number of ALD cycles at a rate of ∼0.7 Å/cycle. The process allows for a high N-to-P ratio in the films, which is beneficial for achieving the required high ionic conductivity. For a film deposited at 330 °C with a composition of Li0.95PO3.00N0.60 according to RBS/NRA analysis, an ionic conductivity value as high as 6.6 × 10–7 S cm–1 is measured at 25 °C.

Formation of six-coordinated silicon in calcium phosphosilicate xerogels assisted by polyols at low temperature and pressure

Abstract Silicon is usually found to be four-coordinated when neighbored with oxygen. Six-coordinated silicon is only seen in samples at very specific composition or made at high temperature/pressure. In this study, we managed to synthesize calcium phosphosilicate xerogels containing six-coordinated silicon with the help of polyols by sol–gel method, without the need of treatment at high temperature or high pressure. Both phosphorus precursors and polyols were found to be essential for the formation of six-coordinated silicon species; in the absence of either species, only normal four-coordinated silicon was observed under otherwise identical conditions. Samples containing six-coordinated silicon sites were found to release silicon species faster than those without six-coordinated silicon sites upon dissolved in water, suggesting that six-coordinated silicon species have higher reactivity toward hydrolysis.

Vapor–Solid growth of InP and Ga2O3 based composite nanowires

InP/Ga 2 O 3 core-shell nanowires were grown on Si substrate at 400 oC in the hydrazine (N 2 H 4 ) vapor diluted with 3 mol. % H 2 O. The crystalline InP and solid Ga served as source materials for the growth of nanowires. According to TEM and EDX data the nanowires consisted of wurtzite InP core with an amorphous Ga 2 O 3 shell. The minimum diameter of NWs was 14 nm, while the maximum lengths reached several micrometers. The twinned planes appeared in WZ InP core at increased nanowire diameters. Based on the obtained results and possible chemical reactions, the following mechanism was proposed for the growth of core-shell nanowires: pyrolytic decomposition of hydrazine caused the appearance of intermediate NH 2 , NH and H species in the vapor. At elevated temperatures the crystalline InP source was also dissociated to In droplets and phosphorus precursors. At source temperatures close to 600 oC, due to the interaction of In and Ga sources with water molecules and hydrazine decomposition products the volatile Ga 2 O and In 2 O were formed. These molecules reached the Si substrate which was heated to 400oC. The final chemical reaction involved Ga 2 O 3 , I 2 O 3 and phosphorus precursors. As a result of a spontaneous reaction the Ga 2 O 3 and InP phases were produced and segregated. The InP crystallized as a core while Ga 2 O 3 created the amorphous shell, because the growth temperature was insufficient for its crystallization.

Synthesis of Li3V2(PO4)3/C with enhanced rate performance by a two-step technique

The nano-particles, Li3V2(PO4)3 embedded in carbon matrix, are synthesized by a novel two-step procedure based on a sol–gel method. In the two-step process, the carbon-encapsulated trivalent vanadium phosphorus precursors are obtained without adding lithium compound in the first step. Because of carbon matrix, small particle size of Li3V2(PO4)3/C composite is obtained in the second step, which involves lithiation and heating to 800 °C in argon. The electronic conductivity of Li3V2(PO4)3/C composite is 2.88 × 10−3 S cm−1, increased by five orders of magnitude compared with the pristine Li3V2(PO4)3 (2.3 × 10−8 S cm−1). The prepared Li3V2(PO4)3/C shows high discharge capacity 132 mAh g−1 (3.0–4.3 V), which is up to 99.2 % of the theoretical value, and good high-rate specific discharge capacity, which is greater than 100 mAh g−1 at a rate of 10 C. Even after cycling at 15 C, the charge–discharge performance of the prepared Li3V2(PO4)3/C cathode hardly deteriorates at 1 C indicating that the structure of Li3V2(PO4)3 is not destroyed irreversibly at high rate. The improved electrochemical properties of the Li3V2(PO4)3/C cathode electrodes are also verified by electrochemical impedance spectroscopy.

Optically stimulated luminescence in Cu+ doped lithium orthophosphate

Optically stimulated luminescence (OSL) in Cu+ doped Li3PO4 synthesized by co-precipitation technique using different phosphorus precursors was studied. Changes in the luminescent properties were observed with change in the phosphorus precursors. All the synthesized phosphors showed intense fading but the OSL sensitivity was comparable to that of the commercially available Al2O3:C (Landauer Inc.). In general, BSL (blue stimulated luminescence) decay was very fast but the GSL (green stimulated luminescence) decay was comparable to that of Al2O3:C phosphor. Phosphors with fast decay, good sensitivity and intense fading are suitable for real-time dosimetry. Therefore, Cu-doped Li3PO4 could be developed for real-time dosimetry using a fiber optic based OSL reader system.

Additional doping of phosphorus into polypyrrole functionalized nitrogenous carbon nanotubes as novel metal-free oxygen reduction electrocatalyst in alkaline solution

Novel phosphorus-doped polypyrrole functionalized nitrogenous carbon nanotubes (P/NCNTs) was developed for the first time as metal-free electrocatalyst for enhancing the oxygen reduction reaction (ORR) activity in alkaline medium. The P/NCNTs was successfully synthesized by pyrolyzing PPy and triphenylphosphane (TPP) under N2, using pyrrole as carbon and nitrogen precursors, TPP as phosphorus precursor. Various characterizations such as transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectra, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) reveal that the P/NCNTs material has covalently bound P atoms with carbon framework, which can introduce defect sites and can induce uneven charge distribution. Moreover, the content of pyridine N increased after P-doping, which is of great significance in improving the ORR activity. The electrochemical behavior of the resultant material shows that the P/NCNTs has much enhanced electroactivity and better stability for ORR. Additionally, a direct four-electron pathway occurred efficiently on P/NCNTs modified electrode. These enhanced performances indicate that P/NCNTs catalyst may be an excellent cathode catalyst for ORR.

Densification and Mechanical Behavior of β-Tricalcium Phosphate Bioceramics

Nano-size β-tricalcium phosphate powders with average grain size of 80 nm were prepared by the wet chemical precipitation method with calcium nitrate and di-ammonium hydrogen phosphate as calcium and phosphorus precursors, respectively. The precipitation process employed was also found to be suitable for the production of sub-micrometre β-TCP powder in situ. The sinterability of the nano-size powders, and the microstructure, mechanical strength of the prepared β-TCP bioceramics were investigated. Bioceramic sample characterization was achieved by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), and density measurements. Powders compacted and sintered at 800, 900, 1000 and 1100 °C showed an increase in relative density from 70 % to 93 %. The results revealed that the maximum hardness of 240 H was obtained for β-TCP sintered at 1100 °C.

Densification and Mechanical Behavior of β-Tricalcium Phosphate Bioceramics

Nano-size β-tricalcium phosphate powders with average grain size of 80 nm were prepared by the wet chemical precipitation method with calcium nitrate and di-ammonium hydrogen phosphate as calcium and phosphorus precursors, respectively. The precipitation process employed was also found to be suitable for the production of sub-micrometre β-TCP powder in situ. The sinterability of the nano-size powders, and the microstructure, mechanical strength of the prepared β-TCP bioceramics were investigated. Bioceramic sample characterization was achieved by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), and density measurements. Powders compacted and sintered at 800, 900, 1000 and 1100 °C showed an increase in relative density from 70 % to 93 %. The results revealed that the maximum hardness of 240 H was obtained for β-TCP sintered at 1100 °C.