Local Structures and Decomposed Phases of Laser-Melted ZrSiO4
Behaviors of CO2 and pulsed YAG laser melting of ZrSiO4 have been investigated using infrared (IR) spectroscopy. The laser-melted ZrSiO4 decomposed into binary oxides (ZrO2 and SiO2), while other phases or complex ZrSiO4 tetrahedron networks are also observed. The local structures and the phases of the quenched melts depend strongly on the quenching rate and melting conditions. Monoclinic ZrO2 are found to be the main ZrO2 phase in the samples treated by CO2 laser, although tetragonal ZrO2 was found near boundaries between the untreated and melted regions. High concentrations of tetragonal ZrO2 were detected in the samples treated by pulsed YAG lasers. Observations indicate that the formation of tetragonal ZrO2 is related to relatively high quench rates. Micro-IR data from areas near the boundaries between the quenched melts and untreated zircon show systematic variations of local structures and compositions. A small region with relatively low density between the untreated and melted boundaries was observed, which consists of tetragonal ZrO2 or glassy ZrO2, and SiO2. Broad vibrational bands occur in the wave number region where the characteristic frequencies of zircon are located. This observation could indicate the possible existence of small amounts of glassy ZrSiO4 in the melt state of zircon, although zircon tends to decompose above the melting point.
Wei Pan and Jianghong Gong
W. Y. Wang et al., "Local Structures and Decomposed Phases of Laser-Melted ZrSiO4", Key Engineering Materials, Vols. 368-372, pp. 1552-1554, 2008