The Synthesis And Characterization Of Jadeite Doped With Cr Via HPHT

Jadeite possesses high artistic value.In the ancient times,wearing jadeite was the symbol of the identity and status.At present,it possesses high collection value because the natural jadeite is extremely rare.Jadeite is a kind of silicate rock and its main component is jadeite jade.The collect information shows that these properties of physical and chemical of magmatic liquids could interpret the formation and evolution of magma in the Earth,igneous processes and volcanism.At the same time,it is very important for us to understand the formation and deformation mechanism of silicate rocks.We choose Na₂SiO₃·9H₂O and Al₂?Si O3?3 as the initial raw materials.We study and imitate the formation environment of natural jadeite through the high pressure and high temperature?HPHT?method.The obtained conclusions are as following.1.We make sure the safe and stable synthetic cavity assembly,on the basis of the work experience of pressure transmitting medium,insulation medium,heating device and the constant validation and improvement,ultimately.2.For the initial raw materials,we choose the high purity Al₂?SiO₃?₃ and Na₂SiO₃ powders and then mix them sufficiently in mole ratio of 1:1.Comparing with other methods,it is easy to control the amount of raw material.At the same time,it also can reduce the excessive products.By optimizing the treatment processes with the initial raw material,we get the homogeneous mixture material.The improvement processes embody in the following two aspects.On the one hand,in order to increase the uniformity of raw materials so we mix them again after grinding.On the other hand,after heating the mixture in crucible up to 1200? for four hours by the oven,we bring it down to the room temperature.And then heated the mixture to 1200? again.In order to analyze the composition and crystalline state of the mixture powder,the characterization of X-ray diffraction?XRD?and Scanning electron microscopy?SEM?is carried out and the results show that the glass material is amorphous and the composition is complicated.The composition of glass material has two main kinds of products: the one is the decomposition products of raw material;the other one is synthetic products of decomposition products.We call it the glass material.3.The HPHT method is successfully used to synthesize green jadeite under 4.0-5.0GPa,at 1000-1500? by adding a small amount of Cr2O3 to the raw materials.The characterization of XRD,SEM all demonstrates that the color of the synthetic jadeite samples turn wood green to green with the increase of the synthetic temperature.The temperature of the high quality synthetic jadeite samples turn down when the preparation of pressure reduce.At the same time,can be obtained the scope of the composition of jadeite samples are narrow.4.In order to explore the formation and deformation mechanism of the nature jadeite.The HPHT method is successfully used to synthesize green jadeite under 3.5GPa,at different temperature by adding a small amount of Cr₂O₃ to the raw materials.The characterization of XRD,SEM,fourier-transform infrared?FTIR?and raman scattering and others indicate that the jadeite is successfully synthesized under 3.5GPa,at 1260?by using the HPHT method and the main components of the synthetic jadeite samples is all Na Al?SiO₃?₂.What is more,The characterization of optical imagines,XRD and EDS show that the sample is consistent with those of the natural jadeite in terms of the color,degree of crystallinity.The SEM spectra indicate that the micro-structure of the sample resembles that of the natural jadeite especially,they both have highly ordered and interpenetrating fibrous texture.The Raman spectrum and Infrared spectra shows that the characteristic peaks of the sample quite resemble that of the natural jadeite.In addition,they also can demonstrate that the crystal structure of the sample is quite the same as the natural jadeite's crystal structure.At the same time,the hardness and density of the sample are similar to that of natural jadeite.