Advance in ultrasonic spray pyrolysis (USP) for the synthesis of gold nanoparticles

Introduction/purpose: Ultrasonic spray pyrolysis (USP) is usually used for the preparation of submicronic and nanosized gold powders. This is a simple method for a synthesis from an aerosol containing dissolved metallic salts such as gold chloride, gold nitrate, and gold-acetate, obtained in the ultrasonic field using frequencies ranging from 0.8 to 2.5 MHz. Methods: The USP method combines aerosol formation in an ultrasonic field, transport of an aerosol with a carrier gas to the reactor and final reduction of HAuCl4 with a used gas such as hydrogen and carbon monoxide. The thermal decomposition of gold acetate takes place in a neutral atmosphere such as nitrogen and argon at elevated temperatures. The chemical reduction of HAuCl4 takes place in the aqueous phase using sodium citrate and sodium boride after heating water solution. Results: Powders of gold were obtained at room temperature using hydrogen reduction in an ultrasonic field at room temperature from HAuCl4 using a frequency of 0.8 MHz. The obtained gold particles were analysed using scanning electron microscopy (SEM) and energy disperse spectroscopy (EDS). The formed particles are round and agglomerated. An increase in temperature to 260°C and 500°C leads to the formation of spherical and cylindrical gold particles. Conclusion: New improved equipment for an ultrasonic spray pyrolysis synthesis of gold powder from HAuCl4 with hydrogen reduction was offered by PRIZMA, Kragujevac, Serbia, enabling a controlled reduction process with better prevention of piezo transducers in an ultrasonic field and increased aerosol production and its transport to the reaction furnace.

Direct chemical synthesis of L10-FePtAu nanoparticles with high coercivity

We report a facile synthesis of hard magnetic L10-FePtAu nanoparticles by coreduction of Fe(acac)3, Pt(acac)2 (acac = acetylacetonate) and gold acetate in oleylamine.

Ligand Properties of Tri(2-thienyl)- and Tri(2-furyl)phosphine and -arsine (2-C4H3E)3P/As (E = O, S) in Gold(I) Complexes

Tri(2-thienyl)- and tri(2-furyl)phosphine and -arsine (L) have been introduced as ligands to gold(I) chloride and acetate (AuX). Structural studies have shown that in the 1:1 complexes of the type L-Au-X the gold atoms are bound exclusively to the phosphorus/arsenic centers without any intraor intermolecular approach of the donor atoms of the three heterocycles towards the metal atoms. Intermolecular aurophilic bonding is found in the crystals of the [tri(thienyl)phosphine]gold acetate complex, but is absent in crystals of the chloride complexes. The phosphines L have been quaternized with methyl iodide and the resulting phosphonium salts [LMe]I structurally characterized to provide reference data as to the preferred configurational and conformational motifs. The mass spectra of the gold complexes indicate a high stability of the dinuclear cationic species [(LAu)2X]+ with X = Cl, OAc for all ligands L.