12299-98-8Relevant articles and documents
MAGNETIC ORDERING IN MnSe//2.
Chattopadhyay, T.,Rossat-Mignod, J.,Fjellvaag, H.
, p. 65 - 68 (1987)
Neutron diffraction experiments on polycrystalline samples of MnSe//2 performed in the temperature range 1. 8 to 54K show a first-order magnetic phase transition at T//N equals 49 K. The existence of the third-order harmonics below T//N shows the magnetic structure of MnSe//2 to be of commensurate square-wave type given by the wave vectors k equals left bracket 1/301 right bracket and 3k equals left bracket 010 right bracket .
Selective synthesis and magnetic properties of ?±-MnSe and MnSe2 uniform microcrystals
Peng, Qing,Dong, Yajie,Deng, Zhaoxiang,Kou, Huizhong,Gao, Song,Li, Yadong
, p. 9261 - 9265 (2002)
A facile and selective route based on a precipitate slow-release controlled process was developed to produce both high-quality MnSe2 and ?±-MnSe uniform microcrystals in aqueous solution at low temperatures (100-180 ?°C). The magnetic properties of the two samples were investigated in detail. This synthetic method will have potential applications in material science, especially in fabricating diluted magnetic semiconductors. These uniform microcrystals might be useful in microdevices, seed crystals, and magnetic cells.
Synthesis, crystal structures and properties of the polychalcogenides manganese-tris(1,2-ethanediamine)-triselenide [Mn(en)3]Se3 and manganese-tris(1,2-ethanediamine)-monotellurodiselenide[Mn(en) 3]TeSe2
Wendland, Frank,Na?ther, Christian,Bensch, Wolfgang
, p. 871 - 876 (2000)
The reaction of manganese (II)-chloride-tetrahydrate, caesium triselenide and elemental selenium or tellurium in 1,2-ethanediamine (en) under solvothermal conditions leads to the formation of two new isostructural compounds [Mn(en)3]Se3 (1) and [Mn(en)3]TeSe2 (2). The compounds crystallize in the orthorhombic space group Pbcn with the lattice parameters a = 1149.39(9), b = 1506.83(11), c = 935.96(6) pm for 1 and a = 1184.1(2), b = 1495.3(2), c = 949.8(1) pm for 2. Their crystal structures are built up of [Mn(en)3]2+ cations and Se32- or TeSe22- anions, respectively. Each cation is surrounded by six next neighbouring anions, and vice versa. Between the cations and the anions hydrogen bonding is observed. The thermal behaviour was investigated using differential thermal analysis, thermogravimetry as well as X-ray powder diffraction. Completely different properties were found. Compound 1 decomposes in two distinct endothermic steps, while compound 2 shows only one endothermic peak. The weight loss for 1 corresponds roughly to the emission of all en molecules, whereas the weight loss for 2 is significantly lower. The final products are composed of MnSe2 and elemental Se or Te, respectively, and an unknown crystalline phase which is different for the two samples.
A facile method to the cube-like MnSe2 microcrystallines via a hydrothermal process
Wang, Licheng,Chen, Luyang,Luo, Tao,Bao, Keyan,Qian, Yitai
, p. 72 - 75 (2006)
A convenient hydrothermal process was applied to prepare the cube-like MnSe2 microcrystallines through the reaction of MnSO 4·H2O with Se and NaH2PO 2·H2O in aqueous solution at 160 °C for 12 h. Powder X-ray diffraction (XRD) analysis confirmed that the product was the cubic phase of MnSe2 with cell parameter a=6.440 . The chemical composition of the MnSe2 was determined by XPS. The Raman spectrum of MnSe2 presented the peaks of the Se-Se stretching mode at 232.44 and 266.58 cm-1. The images of scanning electron microscope (SEM) and transmission electron microscope (TEM) showed the cube-like morphology of the product with the edge length ranging from 20 to 30 μm. The formation mechanism of the MnSe2 microcrystallines was discussed as well.
Syntheses and crystal structures of the two new polychalcogenides
Wendland, Frank,N?ther, Christian,Bensch, Wolfgang
, p. 629 - 634 (2004)
The solvothermal reaction of MnCl2·4 H2O, K2Se3 and Se in trans-cyclohexane-1,2-diamine (chxn) at 433 K yields dark blue crystals of [Mn(chxn)3]Se6 (1), and the reaction of MnCl2·4 H2O, K2Se 3 and Te under similar conditions gives dark blue crystals of [Mn(chxn)3]2[H2chxn](TeSe2) 2Se (2). While compound (1) crystallises in the orthorhombic space group Pbcn with the lattice parameters a = 13.7017(9), b = 19.9073(8) and c = 10.8058(5) A?, compound (2) crystallises in the monoclinic space group P21 with the lattice parameters a = 9.4396(6), b = 24.2450(2), c = 12.8170(8) A? and β = 91.6(1)°. In both structures discrete complex cations and polychalcogenide anions are found. In (1) the Se6 2- anions form a pseudo-layer arrangement with nearly rectangular pores. The complex cations are encapsulated by the arrangement of the Seg 2- anions. Some short distances between the amino groups of the ligands and the anions indicate weak hydrogen bonding. In compound (2) two independent [Mn(chxn)3]2+ and one unique H2chxn dications, two unique TeSe22- as well as one Se 2- dianion coexist. The two complex cations exhibit different conformations. One of the two TeSe22- anions has the di-protonated chxn molecule in the neighbourhood and short Se?H separations indicate weak hydrogen bonding. The isolated Se2- ion is located above the ring of the di-protonated trans-cyclohexane-1,2-diamine molecule and again a short Se?H separation may be due to a weak hydrogen bond. Compound (1) decomposes in a single step when heated in an Ar atmosphere. In contrast, the thermal decomposition of compound (2) is complex and at least five different steps can be identified.
Lattice parameters values and phase diagram for the Cu2Zn 1-zMnzGeSe4 alloy system
Caldera,Quintero,Morocoima,Moreno,Quintero,Grima-Gallardo,Bocaranda,Henao,Macías,Brice?o,Mora
, p. 253 - 257 (2014)
The T(z) phase diagram of the Cu2Zn1- zMnzGeSe4 alloy system is obtained from X-ray diffraction and differential thermal analysis DTA. At room temperature, the X-ray diffraction data showed that samples in the ranges 0 1). The α and δ fields are separated by a relative wide three-phase field (α + δ + MnSe2). The DTA thermograms were used to construct the phase diagram of the Cu2Zn1-zMn zGeSe4 alloy system. It was confirmed that the Cu 2ZnGeSe4 and Cu2MnGeSe4 compounds melt incongruently. It was observed that undercooling effects occur for samples in the range 0.725 z 0.925.
FAR-INFRARED REFLECTION SPECTRA, TO- AND LO-PHONON FREQUENCIES, COUPLED AND DECOUPLED PLASMON-PHONON MODES, DIELECTRIC CONSTANTS, AND EFFECTIVE DYNAMICAL CHARGES OF MANGANESE, IRON, AND PLATINUM GROUP PYRITE TYPE COMPOUNDS.
Lutz,Schneider,Kliche
, p. 437 - 443 (2008/10/08)
A study is made of the far-infrared reflection spectra, the phonon frequencies, and the optical and dielectric constants of the pyrites RuS//2, RuSe//2, RuTe//2, OsS//2, OsSe//2, OsTe//2, PtP//2, PtAs//2, and PtSb//2.
