Effects of HCl concentration on the growth and negative thermal expansion property of the ZrW 2O 8 nanorods

Abstract

A kind of negative thermal expansion ZrW 2O 8 nanorods were synthesized using a hydrothermal method, followed with a post-annealing at 570 °C for 2 h. Effects of HCl concentration on the microstructure, morphology and negative thermal expansion property in resulting ZrW 2O 8 powders were investigated by X-ray diffraction (XRD) and transmission electron microscope (TEM). Results indicate that the formation of the precursor ZrW 2O 7(OH) 2(H 2O) 2 significantly depends on the HCl concentration, and the precursors ZrW 2O 7(OH) 2(H 2O) 2 can form in the 2–8 mol/L HCl solution. With increasing the concentration of the HCl solutions from 2 to 8 mol/L, the rod-like ZrW 2O 8 particles become more homogeneous, and the average dimension change from 10 μm × 0.5 μm to 700 nm × 50 nm. All the ZrW 2O 8 powders obtained in different conditions exhibit negative thermal expansion property, and the average negative thermal expansion coefficients from 15 °C to 600 °C decrease gradually with the increasing HCl concentration.