31052-43-4Relevant articles and documents
RbCu1.2Ag3.8Se3 and Cs2Cu2Sb2Se5: Novel Quaternary Intermetallics Synthesized from Superheated Organic Media
Chen, Zhen,Wang, Ru-Ji,Dilks, Kieran J.,Li, Jing
, p. 132 - 139 (1999)
Reactions in superheated ethylenediamine (en) solutions at 160°C resulted in two novel quaternary intermetallic copper selenides, RbCu1.2Ag3.8Se3(I) and Cs2Cu2Sb2Se5(II). Both I and II are metal rich and represent new layered structure types. Compound I crystallizes in the tetragonal crystal system, space group P4/nbm (No. 125) with a=5.991(1) A, c=10.918(2) A, Z=2, V=391.9(1) A3, R1/wR2=0.0373/0.0458 for all reflections. Compound II belongs to the triclinic crystal system, space group P1 (No. 2), a=7.645(1) A, b=8.768(2) A, c=10.264(1) A, α=91.97(2)°, β=92.07(2)°, γ=103.05(1)°, Z=2, V=669.2(3) A3, R1/wR2=0.0685/0.0740 for all reflections. I consists of 2∞[(Cu1.2Ag3.8Se 3)-] layers and Rb+ counterions located between these layers. There are two types of metal-to-selenium coordination, a square planar (Ag) and a trigonal pyramidal (Cu/Ag). The Se(1) atom displays an unusual eight coordination with Ag and Cu. II contains alternating 2∞[(Cu2Sb2Se5) 2-] anionic and Cs+ cationic layers. Each copper atom has a distorted tetrahedral coordination to four Se atoms, and each antimony atom bonds to three Se atoms to result in a trigonal pyramidal geometry. Both I and II are semiconductors with estimated band gaps of 0.7-0.8 and 1.2-1.3 eV, respectively.
Homologous Alkali Metal Copper Rare-Earth Chalcogenides A2Cu2 nLn4Q7+ n(n = 1, 2, 3)
He, Jiangang,Kanatzidis, Mercouri G.,Laing, Craig C.,Li, Zhi,Quintero, Michael A.,Shen, Jiahong,Weiss, Benjamin E.,Wolverton, Chris,Xia, Yi
, (2022/04/07)
Twenty-seven new members of the A2Cu2nLn4Q7+n (A = Cs, Rb; Ln = La-Nd, Sm, Gd-Yb; Q = S, Se) homologous series were synthesized in one of three structural types (indicated by n = 1, 2, 3). All the compounds contained 3D frameworks with alkali-metal-containing tunnels. For each increment in n, one Cu2Q was added, which was incorporated into the framework as an edge-sharing tetrahedron by replacing a square planar chalcogenide site. High-throughput DFT calculations predicted many of the phases to be thermodynamically stable. These predictions were compared with the synthesis results for the phases formed in each composition space. In the syntheses, heavier lanthanides showed a preference to start forming the n = 3 ACu3Ln2Q5, which is consistent with the predictions. RbCuNd2Se4 and RbCuTb2Se4 were found to be thermally stable under vacuum at temperatures up to 1000 °C. Optical measurements revealed band gaps of 1.55(5) and 1.62(5) eV for CsCuCe2Se4 and RbCuTb2Se4, respectively, and a work function of 4.83(5) eV for CsCuPr2Se4. Additionally, some n = 3 ACu3Ln2Q5 compounds exhibit a negative phonon mode because of a copper atom coordination, which may distort to a trigonal planar geometry at sufficiently low temperatures. The dynamic instabilities and the predicted distortion in the copper tetrahedra for the n = 3 ACu3Ln2Q5 compounds were found to have a linear relationship with the atomic number of the lanthanides and the electronegativity of the lanthanides. The A2Cu2nLn4Q7+n compounds can potentially find application as high-temperature thermoelectric materials and other semiconductors.
Layered and Cubic Semiconductors AGa M′ Q4(A+= K+, Rb+, Cs+, Tl+M′4+= Ge4+, Sn4+Q2-= S2-, Se2-) and High Third-Harmonic Generation
Friedrich, Daniel,Byun, Hye Ryung,Hao, Shiqiang,Patel, Shane,Wolverton, Chris,Jang, Joon Ik,Kanatzidis, Mercouri G.
, p. 17730 - 17742 (2020/11/13)
Eighteen new quaternary chalcogenides AGaM′Q4 (A+ = K+, Rb+, Cs+, Tl+ M′4+ = Ge4+, Sn4+ Q2- = S2-, Se2-) have been prepared by solid-state syntheses and structurally characterized using single-crystal X-ray diffraction techniques. These new phases crystallize in a variety of layered structure types. The tin analogues also adopt an extended three-dimensional network structure as polymorphs. The polymorphism and phase-stability in these cases were studied by thermal analysis and high-temperature in situ X-ray powder diffraction. All compounds are semiconductors with the colored selenides absorbing light in the infrared-green region (1.8 eV a large band gap and shows stability under ambient conditions with no significant irradiation damage.
Helical polymer 1/∞[P2Se62-]: Strong second harmonic generation response and phase-change properties of its K and Rb salts
Chung, In,Malliakas, Christos D.,Jang, Joon I.,Canlas, Christian G.,Weliky, David P.,Kanatzidis, Mercouh G.
, p. 14996 - 15006 (2008/04/06)
The selenophosphates A2P2Se6 (A = K, Rb) crystallize in the chiral trigonal space group P3121, with a = 7.2728(9) A, c = 18.872(4) A, and Z = 3 at 298(2) K and a = 14.4916(7) A, c = 18.7999(17) A, and Z = 12 at 173(2) K for K + salt and a = 7.2982(5) A, c = 19.0019(16) A, and Z = 3 at 100(2) K for Rb+ salt. The A2P2Se 6 feature parallel one-dimensional helical chains of 1/∞[P 2Se62-] which depict an oxidative polymerization of the ethane-like [P2Se6]4- anion. On cooling well below room temperature K2P2Se 6 exhibits a displacive phase transition to a crystallographic subgroup and forms a superstructure with a cell doubling along the a- and b-axes. The Rb analogue does not exhibit the phase transition. The compounds are air stable and show reversible glass-crystal phase-change behavior with a band gap red shift of 0.11 and 0.22 eV for K+ and Rb+ salts, respectively. Raman spectroscopy, 31P magic angle spinning solid-state NMR, and pair distribution function (PDF) analysis for crystalline and glassy K2P2Se6 give further understanding of the phase transition and the local structure of the amorphous state. K 2P2Se6 exhibits excellent mid-IR transparency and a strong second harmonic generation (SHG) response. The SHG response is type-I phase-matchable and in the wavelength range of 1000-2000 nm was measured to be 50 times larger than that of the commercially used material AgGaSe 2. Glassy K2P2Se6 also exhibits an SHG response without the application of electric field poling. In connection with the NLO properties the thermal expansion coefficients for K 2P2Se6 are reported.
