Structural transformations in the As–Se system under high pressures and temperatures
摘要:
The high pressure beta- and gamma-phases of As2Se3, which are metastable at normal conditions, were verified and characterized. The beta-phase of As2Se3 is observed after pressure-temperature treatment at 3 < p <5 GPa in the temperature interval 300 < T< 650 degrees C. It is crystallized according to As2Te3 structure type with the parameters a = 13.465 +/- 0.012 angstrom; b = 3.735 +/- 0.003 angstrom; c = 9.471 +/- 0.008 angstrom; C 2/m; Z = 4; D-x = 5.41 g/cm(3). The gamma-phase of As2Se3 was obtained after treatment at p = 7 GPa and T = 950 degrees C in the form of single crystals for the first time. The parameters of its unit cell are: a = 8.113 +/- 0.009 angstrom; c = 21.08 +/- 0.02 angstrom; D-x = 6.37 glcm(3); Z-6; SG R3m (No. 160) or R (3) over barm (No. 166). A new compound AsSe2 is obtained after treatment at p = 7 GPa and T = 1050 degrees C. This compound does not exist at normal conditions and is crystallized in accordance with the structure type of the high-pressure MoSe2 phase (a = 3.2918 angstrom; c = 19.3238 angstrom; R3m; D = 6.387 g/cm(3); Z = 3). The difference in the behaviors of As2S3 and As2Se3 structural analogs under pressure is discussed from the standpoint of crystal chemistry. (C) 2015 Elsevier B.V. All rights reserved.
Structural transformations in the As–Se system under high pressures and temperatures
摘要:
The high pressure beta- and gamma-phases of As2Se3, which are metastable at normal conditions, were verified and characterized. The beta-phase of As2Se3 is observed after pressure-temperature treatment at 3 < p <5 GPa in the temperature interval 300 < T< 650 degrees C. It is crystallized according to As2Te3 structure type with the parameters a = 13.465 +/- 0.012 angstrom; b = 3.735 +/- 0.003 angstrom; c = 9.471 +/- 0.008 angstrom; C 2/m; Z = 4; D-x = 5.41 g/cm(3). The gamma-phase of As2Se3 was obtained after treatment at p = 7 GPa and T = 950 degrees C in the form of single crystals for the first time. The parameters of its unit cell are: a = 8.113 +/- 0.009 angstrom; c = 21.08 +/- 0.02 angstrom; D-x = 6.37 glcm(3); Z-6; SG R3m (No. 160) or R (3) over barm (No. 166). A new compound AsSe2 is obtained after treatment at p = 7 GPa and T = 1050 degrees C. This compound does not exist at normal conditions and is crystallized in accordance with the structure type of the high-pressure MoSe2 phase (a = 3.2918 angstrom; c = 19.3238 angstrom; R3m; D = 6.387 g/cm(3); Z = 3). The difference in the behaviors of As2S3 and As2Se3 structural analogs under pressure is discussed from the standpoint of crystal chemistry. (C) 2015 Elsevier B.V. All rights reserved.
Synthesis and Structure of the Novel Pentaselenidohexaarsenate(I,II) Cluster Anion [As6Se5]2−
作者:Anna Kromm、William S. Sheldrick
DOI:10.1002/zaac.200700527
日期:2008.5
Methanolothermal reaction of [MnCl3(9-ane-N3)] with As2Se3 at 150 °C in the presence of Cs2CO3 affords violet-coloured [Mn(9-ane-N3)2]As6Se5 (1). Its novel tricyclic selenidoarsenate(I,II) anion [As6Se5]2− contains two five-membered [As3As(Se)Se] rings that are symmetry-related by a crystallographic C2 axis passing through the common AsI-AsI bond between their respective first two ring members. The
[MnCl3(9-ane-N3)] 与 As2Se3 在 150 °C 下在 Cs2CO3 存在下的甲醇热反应得到紫色 [Mn(9-ane-N3)2]As6Se5 (1)。其新颖的三环硒代砷酸盐 (I,II) 阴离子 [As6Se5]2- 包含两个五元 [As3As(Se)Se] 环,它们通过晶体学 C2 轴通过它们各自的第一个键之间的共同 AsI-AsI 键对称相关。两个环成员。各个环中相邻的 AsI 原子由第三个 [As4Se] 环的 Se 原子桥接。
The noncentrosymmetric chain compounds, A3M2AsSe11 (A = K, Rb, Cs; M = Nb, Ta)
作者:Junghwan Do、Mercouri G. Kanatzidis
DOI:10.1016/j.jallcom.2004.03.088
日期:2004.11
The noncentrosymmetric niobium and tantalum selenoarsenates, A(3)Nb(2)AsSe(11), (A = K, Rb, Cs) and K3Ta2AsSe11, were synthesized in a polyselenoarsenate flux. All compounds crystallize in the polar monoclinic space group Cc. The structures are comprised of the same type of infinite chain anions, [M2Se2(Se-2)(3)(AsSe3)](3-) (M = Nb, Ta) separated by alkali metal cations. The As3+ centers with nonbonded electron pairs play an important role in stabilizing the noncentrosymmetric structures. UV-Vis spectroscopy, Raman spectroscopy and differential thermal analysis data are reported. The energy gaps of these compounds vary between 1.35 and 1.53 eV. (C) 2004 Elsevier B.V All rights reserved.
Ohtsuki, T.; Ohno, K.; Shiga, K., Physical Review B: Condensed Matter and Materials Physics, p. 1 - 4
作者:Ohtsuki, T.、Ohno, K.、Shiga, K.、Kawazoe, Y.、Yuki, H.
DOI:——
日期:——
Structural transformations in the As–Se system under high pressures and temperatures
The high pressure beta- and gamma-phases of As2Se3, which are metastable at normal conditions, were verified and characterized. The beta-phase of As2Se3 is observed after pressure-temperature treatment at 3 < p <5 GPa in the temperature interval 300 < T< 650 degrees C. It is crystallized according to As2Te3 structure type with the parameters a = 13.465 +/- 0.012 angstrom; b = 3.735 +/- 0.003 angstrom; c = 9.471 +/- 0.008 angstrom; C 2/m; Z = 4; D-x = 5.41 g/cm(3). The gamma-phase of As2Se3 was obtained after treatment at p = 7 GPa and T = 950 degrees C in the form of single crystals for the first time. The parameters of its unit cell are: a = 8.113 +/- 0.009 angstrom; c = 21.08 +/- 0.02 angstrom; D-x = 6.37 glcm(3); Z-6; SG R3m (No. 160) or R (3) over barm (No. 166). A new compound AsSe2 is obtained after treatment at p = 7 GPa and T = 1050 degrees C. This compound does not exist at normal conditions and is crystallized in accordance with the structure type of the high-pressure MoSe2 phase (a = 3.2918 angstrom; c = 19.3238 angstrom; R3m; D = 6.387 g/cm(3); Z = 3). The difference in the behaviors of As2S3 and As2Se3 structural analogs under pressure is discussed from the standpoint of crystal chemistry. (C) 2015 Elsevier B.V. All rights reserved.