Synthesis and characterizations of AgI nanoparticles via mechanochemical reaction

• Published in: Journal of alloys and compounds Vol. 509; no. 5; pp. 2001 - 2006
• Main Authors: Hawari, Nor Liza, Johan, Mohd Rafie
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 03.02.2011; Elsevier
• Subjects: Activation energy; Alloys; Chemical synthesis methods; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Distilled water; Exact sciences and technology; Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties; Materials science; Mechanochemical technique; Methods of nanofabrication; Morphology; Nanoparticles; Nanopowders; Nanoscale materials and structures: fabrication and characterization; Particle size; Phase transition; Physics; Potassium iodides; Solvents; Superionic phase; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Transmission electron microscopy; Particle size; Superionic phase; Activation energy; Mechanochemical technique; Phase transition; Beta phase; Electrical conductivity; Growth rate; Nitrates; XRD; Mechanical alloying; Phase transitions; Nanoparticles; Time dependence; Gamma phase; Mechanochemical synthesis; Nanomaterial synthesis; Transition temperature; Ball mill; Phase composition; Iodides; Ionic conductivity; Mechanical activation; Superionic conductors; Silver; Transmission electron microscopy; Morphology; Solid state reaction; Growth mechanism; Microstructure; Nanostructured materials
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2010.10.116

▶ The AgI nanoparticles were prepared using a simple mechanochemical route and then sintered at 500 °C for growth study. ▶ It was found that the size of AgI nanoparticles decreases as a function of the milling time. The AgI nanoparticles become homogeneous during mechanical milling. ▶ The morphological changes are followed by structural changes. Most of the XRD peaks at a large angle were disappeared after milling even though they still consist a mixture of two phases β-AgI and γ-AgI. ▶ The DSC study shows that the phase transition temperature (γ → α) slightly decreases after milling. ▶ Ionic conductivity study shows a thermal dependence conductivity which satisfied the Arrhenius profile. ▶ The conductivity is due to the grain boundaries and dislocations. ▶ In addition, we proposed that there would be two different mechanisms for the grain growth as reflected from two different values of the activation energy. Silver iodide (AgI) nanoparticles were prepared by mechanochemical reaction technique (MCR) using silver nitrate (AgNO 3) and potassium iodide (KI) as reagents and distilled water as solvent. Mechanochemical reaction involves the mechanical activation of solid-state displacement reactions at low temperatures in a ball mill. AgI nanoparticles with well-defined morphology, size and phase compositions were obtained. TEM images show that the particle size of the AgI nanoparticles decreases as a function of milling time. The powder X-ray diffraction patterns show that they are mixture of γ- and β-phases. The superionic phase transition temperature (γ → α) was slightly decreased after milling. The ionic conductivity shows enhancement with temperature for all samples with the unmilled sample has the highest conductivity (4.12 × 10 −6 S cm −1) at room temperature. The growth kinetics for AgI nanoparticles were investigated. Two different values of activation energy were obtained indicated that there were two kind of mechanisms for the growth of AgI nanoparticles.