Isolation of cubic Si3P4 in the form of nanocrystals

This article describes an approach for synthesizing silicon phosphide nanoparticles with a defective zinc blende structure under mild conditions through thermal annealing of hydrogenated silicon nanoparticles with red phosphorus. The synthesized Si3P4 nanoparticles were analyzed using FTIR, XRD, electron diffraction, EDX, TEM, Raman spectroscopy, X-ray fluorescence spectrometry, and UV–vis spectrophotometry. For the isolated cubic Si3P4 phase, a cell parameter of a = 5.04 Å was determined, and the bandgap was estimated to be equal to 1.25 eV. Because of the nanoscale dimensions of the obtained Si3P4 nanoparticles, the product may exhibit several exceptional properties as a precursor for diffusion doping of wafers and as anode material for Li-ion batteries. A similar method with a hydrogenation step offers the possibility to obtain other compounds, such as silicon selenides, arsenides, and sulfides

Powder Synthesized from Aqueous Solution of Calcium Nitrate and Mixed-Anionic Solution of Orthophosphate and Silicate Anions for Bioceramics Production

Synthesis from mixed-anionic aqueous solutions is a novel approach to obtain active powders for bioceramics production in the CaO-SiO2-P2O5-Na2O system. In this work, powders were prepared using precipitation from aqueous solutions of the following precursors: Ca(NO3)2 and Na2HPO4 (CaP); Ca(NO3)2 and Na2SiO3 (CaSi); and Ca(NO3)2, Na2HPO4 and Na2SiO3 (CaPSi). Phase composition of the CaP powder included brushite CaHPO4‧2H2O and the CaSi powder included calcium silicate hydrate. Phase composition of the CaPSi powder consisted of the amorphous phase (presumably containing hydrated quasi-amorphous calcium phosphate and calcium silicate phase). All synthesized powders contained NaNO3 as a by-product. The total weight loss after heating up to 1000 °C for the CaP sample—28.3%, for the CaSi sample—38.8% and for the CaPSi sample was 29%. Phase composition of the ceramic samples after the heat treatment at 1000 °C based on the CaP powder contained β-NaCaPO4 and β-Ca2P2O7, the ceramic samples based on the CaSi powder contained α-CaSiO3 and Na2Ca2Si2O7, while the ceramics obtained from the CaPSi powder contained sodium rhenanite β-NaCaPO4, wollastonite α-CaSiO3 and Na3Ca6(PO4)5. The densest ceramic sample was obtained in CaO-SiO2-P2O5-Na2O system at 900 °C from the CaP powder (ρ = 2.53 g/cm3), while the other samples had densities of 0.93 g/cm3 (CaSi) and 1.22 (CaPSi) at the same temperature. The ceramics prepared in this system contain biocompatible and bioresorbable phases, and can be recommended for use in medicine for bone-defect treatment

Powder Synthesized from Aqueous Solution of Calcium Nitrate and Mixed-Anionic Solution of Orthophosphate and Silicate Anions for Bioceramics Production

Synthesis from mixed-anionic aqueous solutions is a novel approach to obtain active powders for bioceramics production in the CaO-SiO2-P2O5-Na2O system. In this work, powders were prepared using precipitation from aqueous solutions of the following precursors: Ca(NO3)2 and Na2HPO4 (CaP); Ca(NO3)2 and Na2SiO3 (CaSi); and Ca(NO3)2, Na2HPO4 and Na2SiO3 (CaPSi). Phase composition of the CaP powder included brushite CaHPO4‧2H2O and the CaSi powder included calcium silicate hydrate. Phase composition of the CaPSi powder consisted of the amorphous phase (presumably containing hydrated quasi-amorphous calcium phosphate and calcium silicate phase). All synthesized powders contained NaNO3 as a by-product. The total weight loss after heating up to 1000 °C for the CaP sample—28.3%, for the CaSi sample—38.8% and for the CaPSi sample was 29%. Phase composition of the ceramic samples after the heat treatment at 1000 °C based on the CaP powder contained β-NaCaPO4 and β-Ca2P2O7, the ceramic samples based on the CaSi powder contained α-CaSiO3 and Na2Ca2Si2O7, while the ceramics obtained from the CaPSi powder contained sodium rhenanite β-NaCaPO4, wollastonite α-CaSiO3 and Na3Ca6(PO4)5. The densest ceramic sample was obtained in CaO-SiO2-P2O5-Na2O system at 900 °C from the CaP powder (ρ = 2.53 g/cm3), while the other samples had densities of 0.93 g/cm3 (CaSi) and 1.22 (CaPSi) at the same temperature. The ceramics prepared in this system contain biocompatible and bioresorbable phases, and can be recommended for use in medicine for bone-defect treatment

NESTOR: A status report

NESTOR is an underwater neutrino astrophysics laboratory to be located in the international waters of the southwest of Greece. The first phase of this experiment is the construction and deployment of one hexagonal tower consisting of 168 optical modules, with effective are of 20000m2 for E ⩾ TeV neutrinos. Over the past few years detailed studies of the site have been carried out while many tests have been performed. The current status of the preparation of the experiment and the future plans will be presented