Research In Situ Neutron Diffraction High Pressure Loads

Structure and character of material will appear distinct transformation under high pressure, therefore the development of high pressure experiment technique provides extensive space for investigation field in coacervation matter physics, material science, geochemistry, chemistry, and so on. Requirement of investigation in various subject also accelerate combination between high pressure experiment technique and correlative measurement methods at the same time, these measurement methods continuously develop in order to accommodate requirement of high pressure experiment, higher efficiency of detector and data quality. Neutron diffraction is provided with a lot of advantage, if high pressure combines with high pressure device and come into instruments for in situ high pressure neutron diffraction experiment, it will bring into play the particularly advantage of neutron diffraction in the investigation about structure and character of material. Develop key units of high volume stable high pressure device, gasket design, determination of pressure and in situ high pressure experiment technique have been carried out in these work. The main conclusions are enumerated as following:(1) We prepared complex diamond with excellent performance by changing temperature and pressure conditions. Investigation of complex diamond microstructure versus physic character has been carried out. We obtained optimization sinter technics for complex diamond, and analysed stress distribution with load pressure on the bottom of anvil. The conclusion is that the stress value will be least as bevel is30°. Big size anvils have been developed, the diameter of anvil increased from4mm to8mm, corresponding volume of sample distinct increased(φ>4mm).(2) We choose SiAl, TiZr and amorphization Fe used for gasket, determined ZrTi as zero bakegroud gasket afer measurement intensity and XRD, and designed standard assembly mode. (3) Pressures in cell versus load have been determined by resistance of matter phyas transformation. We carried out pressure experiment used for Bi and ZnTe, obitaned phyas transformation pressure versus load after optimized electrocircuit connection and assembly mode.(4) Negative thermal expansion (NTE) ZrW2O8powders were prepared by solid-state reaction with ZrO2and WO3powders. In situ high-pressure X-ray diffraction measurements for powder ZrW2O8were performed by using diamond anvil cell (DAC) with synchrotron radiation facility. The result shows that powder ZrW2O8is cubic phase with a little WO3. At about0.27GPa and room temperature, the a-ZrW2O8phase transforms into a quenchable orthorhombic structure called the y phase. Upon further compression, the y phase becomes amorphous at the pressure of3.81GPa. The obtained bulk modulus of a-ZrW2O8and y-ZrW2O8are (40±3.8)GPa and (37±3.0)GPa.on all accounts, we primary investigared high volume stable high pressure technique for neutron diffraction, according character of neutron diffraction investigared develop of anvil, gasket design, accurate control of pressure, sample assembly mode and in situ high pressure experiment technique have been carried out in these work.