Synthesis, microstructure and phase control of zirconium tungstate with a CO₂laser

Abstract

Zirconium tungstate was successfully synthesized by rapid solidification with a CO2 laser. Scanning electron microscope observation shows that nano-threads/rods grew horizontally on the surface region and vertically in the interior. The nano-threads in the interior are composed of densely packed nano-crystallites. Raman spectroscopic study shows that the samples solidified in an orthorhombic structure when the laser scan speed was ≥2 mm s−1. This is explained by a compressive stress induced during the rapid solidification process due to a sudden drop of temperature from the molten pool to the ambient. The possibilities for tuning the strength of the compressive stress and controlling the production of different phases of ZrW2O8 are proposed. It is analysed and confirmed that the compressive stress can be effectively reduced by lowering laser scan speed. ZrW2O8 samples with cubic structure are produced with laser scan speed <2 mm s−1.

Synthesis of hafnium tungstate by a CO2 laser and its microstructure and Raman spectroscopic study

“…These requirements are much stricter than those for the synthesis of ZrW 2 O 8 because of the higher melting point of HfO 2 than of ZrO 2 . 13 Figure 3(a) shows the Raman spectrum of hafnium tungstate synthesized by a CO 2 laser with 700 W laser power and 1 mm/s scan speed. For comparison, we show in Fig.…”

“…It is the compressive stress that accounts for the orthorhombic structure of HfW 2 O 8 . 13 High-pressure neutron diffraction and Raman spectroscopic studies showed that an irreversible structural transition from cubic to orthorhombic occurs at 0.6-0.9 GPa. 4 -6 By comparison with these results, it is to be deduced that the pressure induced in the solidification process for the synthesis of HfW 2 O 8 is around 0.6 GPa since the sample is dominated by the˛-phase with only minor content of the -phase.…”

“…In a previous study, we have successfully realized the rapid synthesis of ZrW 2 O 8 with a CO 2 laser under controlled synthesis parameters. 13 In this paper, we report on the synthesis of HfW 2 O 8 with a high power CO 2 laser and its microstructure and Raman spectroscopic study. Laser synthesis is a green manufacturing technique and environment friendly.…”

Synthesis and dielectric properties of textured SrBi2Nb2O9 ceramics via laser rapid solidification

“…Recent research found that pure bulk ceramic materials could also be synthesized through rapid solidification using a high power laser as the heat source [21][22][23][24].…”

Rapid synthesis of La0.9Sr0.1Ga0.8Mg0.2O3− electrolyte by a CO2 laser and its electric properties for intermediate temperature solid state oxide full cells

“…The synthesis of pure bulk materials with laser rapid solidification (LRS) is a relatively new technique [21][22][23][24][25]. In this paper, laser rapid solidification was employed to synthesize LSGM electrolyte and the microstructure and electrical properties of the samples synthesized by laser were studied and compared to the samples synthesized by solid state reactions.…”