Abstract:

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 light interaction with a solid has been selected in this experience to understand the phosphorescence process in a material. This experience will allow students to understand an amazing phenomena which occurs in our quotidian life as the light emission of fireflies, stickers or fireworks. A teaching strategy has been proposed for undergraduate chemistry students, introducing them to the concepts of phosphorescence as well as different techniques of characterization through a simple laboratory session based in the synthesis of a phosphor material. Nowadays, it is a challenge to encourage students to properly understand chemistry and materials science due to the importance that represents in our society.

Luminescence is a spontaneous light emission coming from excited electronic states after the absorption of UV/visible light. These processes include triboluminescence, fluorescence, phosphorescence, chemiluminescence and bioluminescence. In particular, phosphorescence visible light on slow (minute to hour) time scales after the excitation source has been removed. Lanthanide-doped strontium aluminate (SrAl2O4: Eu, Dy) is one of the most widely used phosphor owing to its green environmental properties and their excellent features, like their long-lasting phosphorescence or their potential applications in optoelectronic devices.

The aim of this work is showing an example to understand this energetic concept from the preparation of a phosphorescent material based on the strontium aluminate structure. A new methodology of synthesis derived of the Pechini’s method has been introduced to the students. The importance of lanthanides ions has also been highlighted. Two common characterization techniques in Solid State Chemistry are presented to the students: X-Ray Diffraction and Electron Microscopy. Finally, phosphorescence properties have been studied in order to bring them closer in the complete preparation of a material. It has allowed them to keep in contact during the whole experiment with the three main concepts of Materials Science: synthesis, structure and properties. This fact makes the work interesting not only from the point of view of students, also for teachers of inorganic chemistry and material science and undergraduate students owing to its pedagogical character employing a Problem Based Learning.

Keywords:

Solid State Chemistry, Inorganic Chemistry, phosphorescence, Materials Science.