Synthesis of Negative Thermal Expansion Sc$lt;inf$gt;2$lt;/inf$gt;W$lt;inf$gt;3$lt;/inf$gt;O$lt;inf$gt;12 $lt;/inf$gt;Thin Film

Abstract

Orthorhombic Sc 2 W 3 O 12 thin films were deposited by pulsed laser deposition method. The microstructure, composition and morphology of the Sc 2 W 3 O 12 ceramic target and thin films were investigated using the X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM). The effects of the substrate temperature and oxygen pressure on the Sc 2 W 3 O 12 thin films were studied. The negative thermal expansion (NTE) properties of the Sc 2 W 3 O 12 ceramic target and thin film were characterized using high temperature XRD and thermal mechanical analysis (TMA). Results indicate that the compact orthorhombic Sc 2 W 3 O 12 ceramic target with excellent NTE can be prepared by sintering at 1000 for 6 ℃ h. The average thermal expansion coefficient of the orthorhombic Sc 2 W 3 O 12 ceramic target is -5.28×10 -6 K -1 from room temperature to 600 . A ℃ ll the as-deposited Sc 2 W 3 O 12 thin films are amorphous. The surface of the as-deposited Sc 2 W 3 O 12 thin film becomes smoother, but it becomes uneven when the substrate temperature increases. The Sc 2 W 3 O 12 thin film with excellent NTE is crystallized after annealing at 1000 for 7 min. The ℃ thermal expansion coefficient of the orthorhombic Sc 2 W 3 O 12 thin film is calculated to be -7.17×10 -6 K -1 in the temperature range from room temperature to 600 . ℃