Self-luminescent Tungstate/Molybdate Film Materials

CaWO₄, PbWO4, NaBi(WO₄)₂ and CaMoO₄ crystals with scheelite structure (ABO₄) are better scintillators or X-ray emitters. The results show that the molybdate and tungstate with scheelite structure belong to tetragonal system, and their grains are tetragonal, biconical or plate-like. They are important photoelectric functional materials, scintillating materials and fluorescent materials.

Previous studies have shown that uncrystallized or inadequately crystallized scheelite films do not have luminescent properties, and the defects in the films will greatly affect the luminescent properties of scheelite structure films. In traditional preparation methods, such as radio frequency sputtering or chemical vapor deposition, a heat treatment process is often needed to crystallize the films. The volatility of WO₃ and MoO₃ results in defects in the prepared tungstate or molybdate films, which results in the degradation of the luminescent properties of tungstate and molybdate films. Therefore, the preparation of high quality tungstate and molybdate thin films at lower temperatures has become a key technology.

In order to overcome the shortcomings of tungstate and molybdate thin films prepared by traditional thin film preparation technology, researchers used the principle of galvanic cell to prepare crystalline scheelite structured luminescent film materials directly in aqueous solution without heating, thus achieving high quality tungstate and molybdate thin films at lower temperatures.

The process is to connect the metal substrate of scheelite luminescent film with platinum sheet by wire and put it into alkaline solution containing corresponding metal cations Ca, Ba, Sr, Pb, Cd or NaBi to form a primary battery system. The metal substrate is tungsten sheet or molybdenum sheet as cathode, platinum sheet as anode, and on the cathode. Tungstate or molybdate films were grown. The defects in the crystallization process of the films prepared by traditional methods are avoided without heating. The films show a single scheelite structure and crystalline state. The luminescent properties of CaMoO₄, SrMoO₄, CaWO₄ and SrWO₄ films are observed at room temperature.

• < Prev
• Next >