Brazhkin, V. V.*; Katayama, Yoshinori; Kanzaki, Masami*; Lyapin, A. G.*
Advances in Chemical Physics, Vol.152, p.29 - 50, 2013/04
In recent years, transformations in the melts of elementary substances and oxides have been found under high pressure. These transformations are accompanied by structural changes and variations in physical properties. In this work, structure and viscosity of Se, AsS, AsS, AsS and BO were studied using synchrotron radiation. These substances exhibit changes in bonding in the crystalline state under high pressure. An X-ray diffraction measurements and falling sphere viscosity measurements using an X-ray radiography technique were carried out. Huge change in viscosity which accompanies structural change under compression was observed in each substance.
Brazhkin, V. V.*; Katayama, Yoshinori; Kanzaki, Masami*; Kondrin, M. V.*; Lyapin, A. G.*
JETP Letters, 94(2), p.161 - 170, 2011/09
It is known that a number of compressed melts undergo structural phase transitions. Data on the structural changes at high pressures in chalcogenides (AsS, AsS) and oxide (BO) melts with a network structure have been reviewed. Viscosity is one of the fundamental physical properties of a liquid. For various melts, it varies in a very wide range. Structural transformations in melts induce the corresponding changes in all physical properties, in particular viscosity. The measurements of the viscosity of a number of melts at high pressures and temperatures by the radiographic method have been reported. Changes in the viscosity by several orders of magnitude have been detected when the pressure is varied by several gigapascals. The diffusion mechanism in network structure melts at various pressures has been analyzed.
Brazhkin, V. V.*; Farnan, I.*; Funakoshi, Kenichi*; Kanzaki, Masami*; Katayama, Yoshinori; Lyapin, A. G.*; Saito, Hiroyuki
Physical Review Letters, 105(11), p.115701_1 - 115701_4, 2010/09
Liquid BO represents an archetypical oxide melt with the cation coordination number 3 and unusual structural units - planar boroxol rings. It features super-high viscosity at melting temperature. The results of the X-ray diffraction study and viscosity measurements of the BO liquid under high pressure up to 8 GPa are presented. Additionally, the NMR study of BO glasses quenched from the melt at different pressures has been carried out. The number of the boroxol rings in the melt rapidly decreases with pressure. The viscosity of the BO melt along the melting curve drops by 4 orders of magnitude as the pressure increases up to 5.5 GPa and remains unchanged on further pressure increase.
Brazhkin, V. V.*; Kanzaki, Masami*; Funakoshi, Kenichi*; Katayama, Yoshinori
Physical Review Letters, 102(11), p.115901_1 - 115901_4, 2009/03
As-S liquid undergoes structural transformation form a molecular liquid into a polymerized one, then into a metallic one. We have measured the viscosity of the As-S liquid under high pressures and found large viscosity variations by 4-5 orders of magnitude. The viscosity values of the As-s liquids are moderate in the molecular state, very high in the covalent state, and low in the metallic state. From these results, it is possible to predict the viscosity behavior in other melts under pressure. The possibility of varying the viscosity value of the melts under pressure by many orders of magnitude is of great importance for materials science and earth science.
Brazhkin, V. V.*; Funakoshi, Kenichi*; Kanzaki, Masami*; Katayama, Yoshinori
Physical Review Letters, 99(24), p.245901_1 - 245901_4, 2007/12
Viscosity is one of the fundamental physical properties of liquids; for different melts it varies in an extremely wide range. Selenium is among the first elementary substances to have manifested, at compression, a phase transformation in the liquid state accompanied by melt metallization. Direct measurements by means of a real-time radiography show that the viscosity of liquid Se under pressure drops by 500 times to a very low level of 8 mPa s. This is the first case of viscosity measurements being performed both for a relatively viscous semiconducting state and a low-viscous metallic state of the same liquid substance. The viscosity of the Se melt strongly decreases with pressure along the melting curve in a semiconducting state and experiences a further significant drop at melt metallization. A similar phenomenon is expected to be observed in many chalcohenide, halogenide and oxide melts.
Katsura, Tomoo*; Yamada, Hitoshi*; Shimmei, Toru*; Kubo, Atsushi*; Ono, Shigeaki*; Kanzaki, Masami*; Yoneda, Akira*; Walter, M. J.*; Ito, Eiji*; Urakawa, Satoru*; et al.
Physics of the Earth and Planetary Interiors, 136(1-2), p.11 - 24, 2003/04
no abstracts in English
Ono, Shigeaki*; Katsura, Tomoo*; Ito, Eiji*; Kanzaki, Masami*; Yoneda, Akira*; Walter, M.*; Urakawa, Satoru*; Utsumi, Wataru; Funakoshi, Kenichi*
Geophysical Research Letters, 28(5), p.835 - 838, 2001/03
no abstracts in English