3:00 PM - 3:15 PM
[SIT22-05] Ultrahigh-pressure synthesis of transparent nano-ceramics and their applications to Earth and planetary sciences
Keywords:transparent nano-ceramics, ultrahigh-pressure synthesis, nano-polycrystalline diamond
Ceramics are polycrystalline materials made of silicates, oxides, nitrides, etc., which are generally opaque due to the presence of inter-crystalline pores and impurities. Ceramics have low thermal/electric conductivities and are used for various industrial and home applications. Recent advancements of sintering techniques have made it possible to produce virtually pore-free and highly transparent ceramics (“transparent ceramics”), which have been commercially applied to some optical devices, including lenses, laser materials, scintillators, etc. These ceramics are made of crystals with cubic crystallographic symmetries, but those of crystals with non-cubic symmetries would also become highly transparent if the grain sizes are in the nano-regime (< 100 nm), being far smaller than the wave-length of visible light. However, it is difficult to synthesize such nano-ceramics without pores using conventional sintering techniques.
We succeeded to synthesize nano-ceramics, such as nano-polycrystalline diamond (NPD; “Hime-diamond”) and garnet, under ultrahigh pressures using multi-anvil apparatus. These nano-ceramics exhibit high optical transparency, and are harder than the corresponding single crystals. Some of them even show high toughness and thermal durability, and are expected to be useful in some industrial applications. In fact, NPD has been successfully commercialized and also used for various scientific applications, particularly in high-pressure sciences. Other such nano-ceramics have been used for specimens for Brillouin scattering measurements and shock-compression experiments. I will review aspects of synthesis and features of these “transparent-nano ceramics”, and showcase some examples of their applications in Earth and planetary sciences.
We succeeded to synthesize nano-ceramics, such as nano-polycrystalline diamond (NPD; “Hime-diamond”) and garnet, under ultrahigh pressures using multi-anvil apparatus. These nano-ceramics exhibit high optical transparency, and are harder than the corresponding single crystals. Some of them even show high toughness and thermal durability, and are expected to be useful in some industrial applications. In fact, NPD has been successfully commercialized and also used for various scientific applications, particularly in high-pressure sciences. Other such nano-ceramics have been used for specimens for Brillouin scattering measurements and shock-compression experiments. I will review aspects of synthesis and features of these “transparent-nano ceramics”, and showcase some examples of their applications in Earth and planetary sciences.