Chemistry at high pressures and temperatures: in-situ synthesis and characterization of (beta)-Si(sub 3)N(sub 4) by DAC X-ray/laser-heating studies

摘要

We have developed in-situ XRD technique at high pressures and temperatures by integrating the angle-resolved synchrotron XRD method, laser-heating system, and diamond anvil cell together. Using this technique, we have studied the direct elementary reactions of nitrogen with Si, yielding technologically important (beta)-Si(sub 3)N(sub 4). These reactions do not occur at ambient temperatures at high pressures up to 50 GPa, but proceed exothermically at high temperatures at moderate pressures. It implies that the reaction is kinetically limited by a large activation barrier.