Synthesis and characterization of NaAlSi_2O_6 jadeite under 3.5 GPa

The high pressure and high temperature (HPHT) method is successfully used to synthesize jadeite in a temperature range of 1000℃-1400℃ under a pressure of 3.5 GPa. The initial raw materials are Na₂SiO₃·9H₂O and Al₂(SiO₃)₃. Through the HPHT method, the amorphous glass material is entirely converted into crystalline jadeite. We can obtain the good-quality jadeite by optimizing the reaction pressure and temperature. The measurements of x-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) and Raman scattering indicate that the properties of synthesized jadeite at 1260℃ under 3.5 GPa are extremely similar to those of the natural jadeite. What is more, the results will be valuable for understanding the formation process of natural jadeite. This work also reveals the mechanism for metamorphism of magma in the earth.