Coiled armrings: an Hiberno-Viking silver arm-ring type

The purpose of this paper is to isolate and discuss a distinctive type of Hiberno-Viking silver armring. Here termed the 'coiled armring', it is dated to the late ninth/early tenth centuries. The methods of manufacture, ornamentation, date and origins of the type are discussed and the objects are assessed against the background of hoard-associated material and related types of silver armrings. A descriptive catalogue of the material is provided.

Controlling alloy formation and optical properties by galvanic replacement of sub-20 nm silver nanoparticles in organic media

Galvanic replacement is a versatile synthetic strategy for the synthesis of alloy and hollow nanostructures. The structural evolution of single crystalline and multiply twinned nanoparticles <20 nm in diameter and capped with oleylamine is systematically studied. Changes in chemical composition are dependent on the size and crystallinity of the parent nanoparticle. The effects of reaction temperature and rate of precursor addition are also investigated. Galvanic replacement of single crystal spherical and truncated cubic nanoparticles follows the same mechanism to form hollow octahedral nanoparticles, a mechanism which is not observed for galvanic replacement of Ag templates in aqueous systems. Multiply twinned nanoparticles can form nanorings or solid alloys by manipulating the reaction conditions. Oleylamine-capped Ag nanoparticles are highly adaptable templates to synthesize a range of hollow and alloy nanostructures with tuneable localised surface plasmon resonance.