Electrochemical Approximation to Bronze Age Chronology via Multiple Scan Voltammetry

Abstract

Insert A multiple‐scan voltammetry strategy is described and applied to a set of 107 Bronze Age and later copper/bronze objects, mainly from sites in Central Europe. This methodology allows the study of the compositional and textural properties (compactness, crystallinity, degree of hydration) of the patina to be studied from the accumulated peak current values for the characteristic signals corresponding to the reduction of cuprite and tenorite to metallic copper. A new model for the relationship between peak current and the depth reached in successive scans is presented and used to discriminate samples of different provenance and manufacturing technique, as well as their ascription to different Bronze Age periods

Mott–Schottky Analysis of Historical and Archaeological Copper–based Objects

“…These processes yield signals at À 0.1 and À 0.4 V. [26][27][28][29] However, this second signal is superimposed by some background current associated with the reduction of dissolved oxygen. When the potential scan is subsequently reversed, an anodic peak, often with peak splitting, is recorded at ca.…”

“…When the potential scan is subsequently reversed, an anodic peak, often with peak splitting, is recorded at ca. 0.0 V. [26][27][28][29] This peak corresponds to the oxidative dissolution of the previously formed copper metal deposit to Cu 2 + (aq) ions in the solution phase. In general, tin-localized voltammetric signals were absent, a result of the well-known destannification phenomenon [6][7][8][9][10] Repeated impedance measurements in the same range of potentials at frequencies between 10 5 and 10 2 Hz revealed qualitatively similar characteristics.…”

“…To model impedance measurements, it must be taken into account that the studied sample-modified working electrodes consist of a series of micrometer-sized laminations [27][28][29] deposited on a graphite base. For modeling purposes, EIS experiments were carried out at the OCP.…”

“…The above treatment applies to continuous films of the semiconducting material forming the working electrode. Our systems, however, consist of a series of micrometer-sized laminations [27][28][29] deposited on a graphite base electrode forming a discontinuous deposit. This can be described by the equivalent circuit in Figure 2.…”

“…[27,28] Application of multiple-scan procedures has been recently applied to obtain archaeometric information on copper/bronze artifacts. [27][28][29] Here, we report a study of the application of a novel technique, Mott-Schottky (MÀ S) plots, derived from impedance measurements, to the study of archaeological metal patinas. This method exploits the semiconducting nature of the most common copper corrosion products (and eventually other patina components such as Sn and Zn oxides), cuprite (Cu 2 O) and tenorite (CuO), both of which are p-type semiconductors with direct band gaps of 2.2 and 1.4 eV, respectively.…”