X-Ray Diffraction Study on Structural Change in Liquid Selenium under High Pressure

Structural transformation yielding an unusual metallic state in liquidAs2S3under high pressure

“…6 Interest in liquid arsenide chalcogenides, such as As 2 S 3 , As 2 Se 3 , and As 2 Te 3 , as well as in elementary liquid Se, S, and Te, is also aroused by the fact that the transition from a semiconductor to a metallic state occurs in these melts at high temperatures and moderate pressures in the supercritical region 7-12 and ͑or͒ under high pressures in the vicinity of the melting curve. [13][14][15][16][17] Similarly, the glassy states of these materials undergo a semiconductor-metal transition under compression at room temperature. 18 The mechanism of the semiconductor-metal transition in these substances has not yet been fully clarified; 7 at any case, it is not the classical Mott-type transition.…”

“…[13][14][15][16] Note that the Se melt, unlike As 2 S 3 and As 2 Se 3 , is not a three-dimensional network but a set of long chains of two-coordinated Se atoms. It is found that near the melting curve, the metallization occurs in a narrow pressure range around 4 GPa and is accompanied by considerable structural changes and a volume contraction by 4-5 %.…”

“…It is found that near the melting curve, the metallization occurs in a narrow pressure range around 4 GPa and is accompanied by considerable structural changes and a volume contraction by 4-5 %. [13][14][15][16] The structural changes involve the break in the chains and the formation of a significant fraction of threecoordinated Se atoms. 14,15 The structure of the Se melt under high pressures becomes similar to that of liquid Te at normal pressure.…”

“…[13][14][15][16] The structural changes involve the break in the chains and the formation of a significant fraction of threecoordinated Se atoms. 14,15 The structure of the Se melt under high pressures becomes similar to that of liquid Te at normal pressure. In doing so, the viscosity of liquid Se drops from moderate values of 0.1-1 Pa s to typical metallic values of 0.005-0.01 Pa s ͑Ref.…”

Chain structure of liquid Se at high temperature and pressure investigated by ab initio molecular dynamics simulations

“…The properties of element selenium have been extensively investigated for the past several years mainly due to the following two reasons [1][2][3][4][5][6]. Firstly, crystalline selenium is one of the elements with the most allotropes next to sulfur and phosphorus, and many allotropes of selenium are of great fascination from the viewpoints of the structure and properties [7].…”