In situ synchrotron X-ray diffraction in the laser-heated diamond anvil cell: Melting phenomena and synthesis of new materials

The ability to produce high pressures and temperatures (P-T), and study the physical and chemical properties of solids and melts at these conditions, is possible through the use of the laser-heated diamond anvil cell (LH-DAC). High P-T experiments are commonly performed at synchrotron radiation facilities, where in situ X-ray diffraction (XRD) permits the detection of melting, crystallographic structural analysis, and density measurements at extreme conditions. Here we present an overview of recent experimental advances in the use of high pressure techniques in combination with laser heating and in situ X-ray diffraction. We summarize state-of-the-art capabilities, including recent advancements, in sample preparation, pressure and temperature measurements, and other technical aspects. Two main applications of the LH-DAC are discussed: the study of the melting curves of elements and compounds at high pressures, and materials synthesis at extreme conditions. The melting curves of Fe, Ta, and MgO are used as examples in a discussion of experimental techniques, technical developments, and sources of discrepancies in melting data. High P-T syntheses of light molecular systems, superhard materials, nitrides, oxides, carbon compounds, and geologically important materials are reviewed.