T:Toxic;
7446-08-4Relevant articles and documents
Study of the system Pr2O3-SeO2-H2O at 100°C and the properties of the compounds obtained
Gospodinov,Stancheva
, p. 95 - 100 (2004)
The solubility of the system Pr2O3-SeO2-H2O at 100°C was studied. The fields of crystallization of Pr2(SeO3)3·H2O, PrH(SeO3)2, Pr(HSeO3/sub
The synthesis and crystal structures of the first rare-earth alkaline-earth selenite chlorides MNd10(SeO3)12Cl8 (M=Ca and Sr)
Berdonosov,Olenev,Dolgikh,Lightfoot
, p. 3019 - 3025 (2007)
Two new alkaline-earth Nd selenite chlorides MNd10(SeO3)12Cl8 (M=Ca, Sr) were obtained using crystal growth from alkaline-earth chloride melts in quartz tubes. These new compounds crystallize in the orthorhombic system in space group C cca (#68). The compounds were studied by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction. It was shown that both compounds adopt the same structure type, constructed by complex [M11(SeO3)12]8+ slabs separated by chloride anion layers perpendicular to the longest cell parameter. The SeO3 groups show a pyramidal shape and may be described as SeO3E tetrahedra. Such SeO3 groups decorate the Nd-O skeletons forming the [M11(SeO3)12]8+ slabs.
Structural and thermal studies on the solid products in the system MnSeO3-SeO2-H2O
Vlaev,Tavlieva, Mariana P.
, p. 385 - 392 (2007)
The solubility of MnSeO3-SeO2-H2O system was studied in the temperature region 25-300°C. The compounds of the three-component system were identified by the Schreinemaker's method. The phase diagram of manganese(II) selenit
Cadmium copper selenite chloride, CdCu2(SeO3)2Cl2, an insulating spin gap system
Berdonosov, Peter S.,Danilovich, Igor L.,Dolgikh, Valery A.,Murtazoev, Alisher F.,Pchelkina, Zlata V.,Tafeenko, Victor A.,Vasiliev, Alexander N.
, (2021)
Novel copper cadmium selenite chloride has been synthesized via vapor transport reaction as well as by solid state process. CdCu2(SeO3)2Cl2 crystallizes in a monoclinic space group I2/a with cell constants a ?= ?7.8057(3) ?, b ?= ?9.6036(4) ?, c ?= ?10.7817(5) ? and β ?= ?102.362(4)°, Z ?= ?4. Its crystal structure can be described as an open channel three-dimensional framework, formed by [CdO2Cl4] and [CuO4Cl2] polyhedra interconnected by pyramidal SeO3 groups. The copper polyhedra form magnetically isolated dimers with a spin gap Δ ?= ?38.7 ?± ?0.8 ?meV, as defined from magnetic susceptibility measurements. The electron band gap estimated by diffuse reflectance method Eg ?= ?2.82 ?± ?0.02 ?eV is in agreement with the yellow-green color of the substance. Density functional theory provides the values of electron (2.4 ?eV) and spin (36.6 ?meV) gaps consistent with experimental observations.
Fuller, M. L.,Siller, C. W.
, p. 416 - 419 (1941)
Synthesis and structural, spectroscopic and magnetic studies of two new polymorphs of Mn(SeO3)·H2O
Larranaga, Aitor,Mesa, Jose L.,Pizarro, Jose L.,Pena,Olazcuaga, Roger,Arriortua, Maria I.,Rojo, Teofilo
, p. 3686 - 3697 (2005)
Two new manganese(II) selenite polymorphs with formula Mn(SeO 3)·H2O have been synthesized by slow evaporation from an aqueous solution. The crystal structure of both compounds (1) and (2) have been solved from X-ray diffraction data. The structure of (1) was determined from single-crystal X-ray diffraction techniques. The compound crystallizes in the Ama2 space group, with a=5.817(1), b=13.449(3), c=4.8765(9)A and Z=4. The structure of (2) has been solved from X-ray powder diffraction data. This phase crystallizes in the P21/n space group with unit-cell parameters of a=4.921(3), b=13.121(7), c=5.816(1)A, β=90.03(2)° and Z=4. Both polymorphs exhibit a layered structure formed by isolated sheets of MnO6 octahedra and (SeO3) 2- trigonal pyramids in the (010) plane. These layers, which contain one manganese and selenium atom crystallographically independent, are formed by octahedra linked between them through the selenite oxoanions. The difference of both compounds consists in the stacking of the layers along the b-axis. The IR spectra show the characteristic bands of the selenite anion. Studies of luminescence performed at 6 K and diffuse reflectance spectroscopy have been carried out for both phases. The Dq and Racah (B and C) parameters, from luminescence and diffuse reflectance spectroscopy, are Dq=705, B=750, C=3325cm-1 for (1) and Dq=720, B=745, C=3350cm-1 for (2). The ESR spectra of both compounds are isotropic with g-values of 1.99(1). Magnetic measurements indicate the presence of antiferromagnetic couplings in both phases. The J-exchange parameters have been estimated by fitting the experimental magnetic data to a model for square-planar lattice. The values obtained are J/k=-0.83, -0.91 K and J′/k=-0.97, -1.20 K, for polymorphs (1) and (2), respectively.
Age-induced phase transitions on mechanically alloyed amorphous GaSe
Campos,de Lima,Grandi,Souza,Pizani
, p. 270 - 275 (2007)
After aging it for four years at room temperature, a mechanically alloyed amorphous GaSe powder was transformed to a multi-phase crystalline alloy, where major phase is the trigonal Se one. The structural, thermal and optical properties of this aged amorphous GaSe were investigated through systematic X-ray diffraction, differential scanning calorimetry and Raman scattering measurements. The X-ray diffraction results on the aged GaSe powder suggest the presence of oxides, and X-ray absorption spectroscopy was employed to further investigate it.
Oxidation of polycrystalline zinc selenide with atmospheric oxygen
Khlopochkina,Gaivoronskii,Gavrishchuk,Elliev,Yashina
, p. 1079 - 1081 (2001)
Oxidation of granulated polycrystalline zinc selenide (grain size 0.2-6.5 mm) with atmospheric oxygen at 430-700°C was studied. The optimal conditions for the oxidation were found. An installation for the oxidation of kilogram amounts of zinc selenide was
Polymorphism in mercury(I) selenite(IV): Preparation, crystal structures of α-, β-and γ-Hg2SeO3, and thermal behavior of the α- and β-modification
Weil, Matthias
, p. 35 - 44 (2003)
Mercury(I) selenite(IV) is polymorphic and crystallizes at least in three modifications, named α-, β-and γ-Hg2SeO3. Polycrystalline β-Hg2SeO3 was prepared by precipitation of a concentrated mercurous nitrate solution with selenous acid. Hydrothermal treatment of the colorless β-Hg2SeO3 powder in demineralized water at 250°C (10days) yields light-yellow single crystals of α-Hg2SeO3 which show the highest density of the three modifications. Colorless needle-shaped single crystals of β-Hg2SeO3 and very few single crystals of γ-Hg2SeO3 co-crystallize from strongly diluted Hg2(NO3)2 and H2SeO3 solutions and were grown by a diffusion technique. All crystal structures were solved and refined from single crystal diffractometer data sets and are based on Hg22+ dumbbells and trigonal pyramidal SeO32- anions as the main building units. A common structural feature of all modifications is the formation of open channels extending parallel to the shortest crystallographic axis. The non-bonding orbitals of the SeIV atoms are stereochemically active and protrude into the channels. Upon heating in an open system under N2 atmosphere, both α- and β-Hg2SeO3 decompose in a well-separated three-step mechanism. The first step (T > 250°C) involves disproportionation into elementary mercury and α-HgSeO3 which at ca. 400°C subsequently transforms into β-HgSeO3. The second step between T = 400 and 500°C is accompanied by a loss of Hg and SeO2 and the formation of the basic salt Hg3SeO6. In the third step, at temperatures between T = 500° and 600°C, this material decomposes completely. Upon heating in a closed system (sealed silica capillaries), β-Hg2SeO3 transforms between 320-340°C into the more dense α-Hg2SeO3 which on further heating likewise converts into elementary mercury and β-HgSeO3.
Synthesis, thermal, spectroscopic and magnetic studies of the Mn(SeO3)·2H2O and Fe2(SeO3)3·3H2O selenites
Larranaga, Aitor,Mesa, Jose L.,Pizarro, Jose L.,Lezama, Luis,Arriortua, Maria I.,Rojo, Teofilo
, p. 1020 - 1026 (2008)
Mn(SeO3)·2H2O (1) and Fe2(SeO3)3·3H2O (2) have been synthesized by slow evaporation from an aqueous solution in the case of (1) and using mild hydrothermal conditions for (2). The crystal structures of both phases have been refined by the Rietveld method. The compounds crystallize in different spatial groups, the P21/n monoclinic one with parameters a = 6.649(1) A, b = 6.542(1) A, c = 10.890(1) A and β = 103.85(1)° being Z = 4 for (1) and the R3c trigonal space group with parameters a = 9.361(1) A, c = 20.276(1) A and Z = 6 for (2). The crystal structure of compound (1) consists of a three-dimensional framework formed by MnO6 octahedra and (SeO3)2- oxoanions with trigonal pyramidal geometry, which gives rise to Mn2O10 dimers of edge-sharing octahedra. The crystal structure of phase (2) can be described as a three-dimensional framework formed by MnO6 octahedra and (SeO3)2- oxoanions with trigonal pyramidal geometry. In this phase the octahedral entities are linked along the three crystallographic axes through the selenite anions. Diffuse reflectance spectrum and luminescent measurements for (1) indicate the existence of Mn2+ cations in a slightly distorted octahedral environment. Diffuse reflectance spectrum and Moessbauer spectroscopy, in the paramagnetic region, for (2) show the existence of Fe3+ cations in slightly distorted octahedral symmetry. ESR spectra of both compounds are isotropic with a g-value of 1.99(1) and 2.00(1), respectively. Magnetic measurements of both phases indicate an antiferromagnetic behavior. For phase (2), both, the ESR and magnetic measurements suggest a spin change from Fe3+ (S = 5/2) to Fe2+ (S = 2) at low temperatures.
Thermodynamic properties and rare-earth spectroscopy of Cu3Nd(SeO3)2O2X (X = Cl, Br)
Markina, Maria M.,Zakharov, Konstantin V.,Berdonosov, Peter S.,Dolgikh, Valery A.,Kuznetsova, Elena S.,Klimin, Sergei A.,Yumashev, Oleg B.,Vasiliev, Alexander N.
, (2019)
The kagome lattice of copper ions in francisite-type compounds is quite sensitive to external stimuli, being easily affected by temperature and magnetic field. The rare-earth ions inserted between buckled layers of transition metal add new dimension to ma
Synthesis and powder X-ray diffraction analysis of new mixed rare-earth and selenium oxychlorides with composition LnSeO3Cl
Shabalin,Berdonosov,Dolgikh,Oppermann,Schmidt,Popovkin
, p. 98 - 102 (2003)
A series of new mixed rare-earth and selenium oxychlorides with composition LnSeO3Cl (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, or Y) were prepared by annealing together LnOCl and SeO2 in sealed silica tubes. The resulting compounds were characterized by powder X-ray diffraction. The unit cell parameters of the phases were determined. Lanthanum - europium oxychlorides crystallized in the tetragonal system to give the Sillen phases analogously to tellurium compounds with the similar formula, whereas Tb-Yb and Y oxychlorides crystallized in the orthorhombic system. It is likely that the latter oxychlorides are not layered compounds.
Synthesis and structure of cyclic selenium oxide SeVISe2IVO7
Touzin,Kilian,Zak
, p. 1617 - 1622 (1996)
Nitromethane is the only presently known organic solvent for highly reactive selenium trioxide (SeO3)4. The stability of the solutions is limited and the beginning of the reaction between both components depends significantly on conc
Strontium nickel and barium nickel selenites: Synthesis and X-ray diffraction parameters
Berdonosov,Batunin,Olenev,Dolgikh
, p. 6 - 12 (2010)
A new strontium nickel selenite, Sr2Ni(SeO3) 3, was prepared and structurally characterized. The compound crystallizes in triclinic system (space group P1?, a = 7.2860(10) ?, b = 7.581(2) ?, c = 8.722(2) ?, α = 103.02(2)°, β = 105.580(10)°, γ = 95.260(10)°, Z = 2) and is isostructural to cobalt and copper analogues. The structure of Sr2Ni(SeO 3)3 is a three-dimensional framework built of eight-vertex polyhedra [SrO8] and distorted octahedra [NiO6] sharing edges and vertices. The framework channels accommodate selenium atoms bonded to the framework oxygen atoms. The selenite groups SeO3 are pyramidal, which is indicative of high stereochemical activity of the Se(IV) lone pair. The possibility of replacement of some Ni atoms by Cu in Sr2Ni(SeO 3)3 was studied. The search for analogous barium phases did not reveal such compounds, but BaM(SeO3)2 phases were found, where M = Co, Ni, or Cu. The unit cell parameters of the new selenite BaM(SeO3)2 were determined: space group Pnma, a = 14.989(5) ?, b = 5.439(2) ?, c = 7.161(3) ?, Z = 4.
Study on the kinetics of isothermal decomposition of selenites from IVB group of the periodic system
Vlaev,Gospodinov,Genieva
, p. 13 - 17 (2004)
The thermal stability and kinetics of isothermal decomposition of the selenites of germanium, tin and lead was studied. A dependence between the process activation energy and the radius and electron polarizability of the cations was observed. It was explained with the different degree of the effect of counterpolarization of the selenite anion. The negative value of the change of entropy of activation showed that the active complex is more complicated formation than the reagent. The higher absolute value of the change of entropy measured for the formation of the active complex Ge(SeO3)2 compared to that for Sn(SeO3)2 shows that the degree of rearrangement (necessary changes) of the initial crystalline structure increases with the decrease of cation radius. The isothermal decomposition of the selenites from IVB group of the periodic system was considered to be 'slow' reaction due to the significantly lower than unity values of the steric factor.
Two new octahedral/pyramidal frameworks containing both cation channels and lone-pair channels: Syntheses and structures of Ba2Mn IIMn2III(SeO3)6 and PbFe2(SeO3)4
Johnston, Magnus G.,Harrison, William T.A.
, p. 4680 - 4686 (2004)
The hydrothermal syntheses, single crystal structures, and some properties of Ba2MnIIMn2III(SeO 3)6 and PbFe2(SeO3)4 are reported. These related phases contain three-dimensional frameworks of vertex (FeO6) and vertex/edge linked (MnO6) octahedra and SeO3 pyramids. In each case, the MO6/SeO3 framework encloses two types of 8 ring channels, one of which encapsulates the extra-framework cations and one of which provides space for the SeIV lone pairs. Crystal data: Ba2Mn3(SeO3) 6, Mr=1201.22, monoclinic, P21/c (No. 14), a=5.4717 (3) A, b=9.0636 (4) A, c=17.6586 (9) A, β=94.519 (1)°, V=873.03 (8) A3, Z=2, R(F)=0.031, wR(F 2)=0.070; PbFe2(SeO3)4, M r=826.73, triclinic, P1- (No. 2), a=5.2318 (5) A, b=6.7925 (6) A, c=7.6445 (7) A, α=94.300 (2)°, β=90.613 (2)°, γ=95.224 (2)°, V=269.73 (4) A3, Z=1, R(F)=0.051, wR(F2)=0.131. Polyhedral view of the structure of the mixed valence barium manganese selenite Ba 2Mn3(SeO3)6 projected onto (100).
Greaves, J. C.,Linnett, J. W.
, p. 1323 - 1330 (1958)
Synthesis, structure, and properties of V2O3(XO 4)2 (X = S, Se)
Tyutyunnik,Krasil'Nikov,Zubkov,Perelyaeva,Baklanova
, p. 501 - 507 (2010)
Compounds described as V2O3(XO4) 2, where X = S or Se, were prepared from vanadium(V) oxide mixtures with concentrated sulfuric and selenic acids. The physicochemical properties of the products were studied; for V2O3(SeO4) 2, the crystal structure was determined by powder X-ray diffraction and neutron diffraction, and its key differences from the structure of V 2O3(SO4)2 were identified. V 2O3(SeO4)2 crystallizes in the monoclinic system with the unit cell parameters a = 15.3831(2)?, b = 5.54096(5)?, c = 9.71644(7)?, β = 111.886(1)°, V = 768.51?3, space group C2/c (no. 15).
Bi6(SeO3)3O5Br2: A new bismuth oxo-selenite bromide
Berdonosov, Peter S.,Kirsanova, Maria A.,Dolgikh, Valery A.,Olenev, Andrei V.,Lebed, Julia B.
, p. 232 - 237,6 (2012)
A new bismuth oxo-selenite bromide Bi6(SeO3) 3O5Br2 was synthesized and structurally characterized. The crystal structure belongs to the triclinic system (space group P1, Z=2, a=7.1253(7) A, b=10.972(1) A, c=12.117(1) A, α=67.765(7)°, β=82.188(8)°, γ=78.445(7)°) and is unrelated to those of other known oxo-selenite halides. It can be considered as an open framework composed of BiOx or BiOyBrz polyhedrons forming channels running along [1 0 0] direction which contain the selenium atoms in pyramidal shape oxygen coordination (SeO3E). The spectroscopic properties and thermal stability were studied. The new compound is stable up to 400 °C.
Formation and thermal stability of selenites and hydrogen selenites of samarium
Gospodinov,Stancheva
, p. 1057 - 1063 (2004)
The solubility isotherm of the Sm2O3-SeO 2-H2O system was studied at 100°C. The two compounds obtained in the three-component system were identified by the Schreinemakers' method as well as by chemical, thermoan
