A way to understand the solid-state chemistry for high level education students: the case of a ceramic pigment

Abstract

The design of undergraduate laboratory sessions that provide meaningful research-based experiences enhances undergraduate curricula and prepares future graduate students for research careers. Solid-State Chemistry has attracted the attention of many fields due to its wealthy chemistry as well as the versatility of its applications. Among the wide fields in this area, the study of an inorganic ceramic pigment has been selected in this experience.

A pigment can be defined as a colored organic or inorganic solid (black, white or fluorescent) normally insoluble and practically unaffected neither chemically nor physically by the vehicle or substrate in which it is incorporated. From a structural point of view, a ceramic pigment is formed by a host network where the chromophore component, usually transition ions, generates the color without producing a change in the structure. A suitable host network must have, in addition to a high chemical resistance against oxidation and reduction and a high melting point, energy differences between favorable bands to allow the chromophore to produce colors in the region of the visible spectrum.

A teaching strategy has been proposed for undergraduate chemistry students, introducing them to the solid-solid reaction by the synthesis of a pink ceramic pigment based on chromium-doped ZnAl2O4 with the spinel structure. The as-prepared pigment has been characterized by two different techniques, such as X-Ray Diffraction and UV-Vis spectroscopy, commonly used in Solid-State Chemistry. In this way, students have a first approach to the basic concepts of the Solid-State Chemistry through simple laboratory sessions.

Due to the easy strategy used in this study, students will be able to participate in an active way, fulfilling the pedagogical character demanded by a Problem-Based Learning (PBL).