Yellow Single Crystals Research Articles

Europium(II) oxyiodide.

Yellow single crystals of Eu4OI6 were grown from fluxes in Ta ampoules and structurally characterized by X-ray diffraction. Eu4OI6 crystallizes in a hexagonal system and is isotypic with the corresponding chloride and bromide compounds. The O atom and one Eu atom lie on sites with 3m symmetry; the other Eu atom and the two unique I atoms are at sites with m symmetry. The structure is characterized by O-centered tetrahedra of divalent europium cations [Eu-O = 2.391 (15) and 2.416 (5) A, and mean Eu-Eu = 3.94 A] and hexagonal channels along [001] filled with iodide anions.

Single Crystal Growth and Crystal Structure of Mercurous Diarsenate(V), (Hg2)2(As2O7)

AbstractPolycrystalline mercurous diarsenate(V), (Hg2)2(As2O7), was prepared by a redox‐reaction between stoichiometric amounts of HgO and As2O3. Canary yellow single crystals were obtained by subsequent chemical transport reactions using HgCl2 as transport agent [550 → 500 °C, 5 d, sealed and evacuated silica ampoules]. The crystal structure (orthorhombic, Pnma, Z = 4, a = 9.9803(8), b = 12.2039(10), c = 7.2374(6)Å) is composed of two crystallographically independent Hg dumbbells (d¯(Hg—Hg) = 2.5133Å) with a symmetric oxygen coordination sphere, and a diarsenate group with a staggered conformation and a bent bridging angle As—O—As = 121.0(7)°. The building units are arranged in a layer‐like assembly parallel to (010) and are connected via common oxygen atoms to form a three‐dimensional network.

Study on crystal structure and thermal behavior of Cs(NTO)·H 2O

A new hydro-compound Cs(NTO)·H 2O has been synthesized by reaction of 3-nitro-1,2,4-triazole-5-one(NTO) with Cs 2CO 3 in aqueous solution and Cs(NTO)·H 2O was recrystallized to be lemon yellow single crystal. Its crystal structure has been determined. This crystal belongs to monoclinic system and crystal structure data: space group P2 1/ n, a=0.6329(1) nm, b=0.8439(1) nm, c=1.3394(2) nm β=96.05°(1). Density (calculated), D c =2.614 g cm −3, V=0.7113(2) nm 3 Z=4, μ=5.0185 mm −1, F(000)=520, R=0.022, wR=0.0501. Cs atom is coordinated with eight oxygen atom of water and nitrogen of NTO. Layer structure is formed by hydrogen bonds. The thermal behavior of this compound is discussed.

Synthese und Kristallstruktur von CsAu(SO4)2Professor Joachim Strähle zum 65. Geburtstag gewidmet

Synthesis and Crystal Structure of CsAu(SO4)2 Light yellow single crystals of CsAu(SO4)2 were obtained upon evaporation of a solution of Au(OH)3 and Cs2SO4 in sulfuric acid (96 % H2SO4). In the crystal structure (monoclinic, P21/c, Z = 4, a = 1029.7(2), b = 893.4(2), c = 901.0(1) pm, β = 111.08(1)°) Au3+ is in square planar coordination of oxygen atoms which belong to four SO4— ions. According to [Au(SO4)4/2]— puckered layers are formed which are connected by the Cs+ ions. The latter are surrounded by five chelating and three monodentate sulfate groups leading to a CN of 13.

1, 3, 4, 4'-Tetra(triphenylphosphanimin)-2-iodo-2-butenal-4-carboniumiodid, [O=C(NPPh3)C(I)=C(NPPh3)-C(NPPh3)2]+I-

Pale yellow single crystals of [O=C(NPPh3)C(I)=C(NPPh3)-C(NPPh3)2]+I-·1.5 thf (1·1.5 thf) have been obtained by the reaction of INPPh3 with thallium in thf suspension. They are characterized by IR spectroscopy and by a crystal structure determination. 1·1.5 thf crystallizes in the monoclinic space group P21/n, Z = 4, lattice dimensions at -83?C: a = 1101.7(1), b = 3449.0(2), c = 2000.4(1) pm, β = 104.88(1)?, R1 = 0.0382. 1 can be understood as a cationic variation of (Z)-2-butenale in which all H atoms are substituted by triphenylphosphoraneimine residues and by a iodine atom, respectively.

The Gold Sulfates MAu(S04)2 (M = Na, K, Rb)

Abstract The evaporation of a solution of Au(OH)3 and Na2So4 in conc. sulfuric acid led to yellow single crystals of NaAu(SO4)2 (monoclinic, P21/n, Z = 2, a = 469.1, b = 845.9, c = 831.2 pm, β = 95.7°). Analogous procedures with K2SO4 or Rb2SO4 instead of Na2SO4 yielded single crystals of KAu(SO4)2 (monoclinic, C2/c, Z = 4, a = 1109.8, b = 724.2, c = 941.1 pm, β = 118.4°) and RbAu(S04)2, respectively, (triclinic, P1̄, Z = 1, a = 423.6, b = 497.5, c = 889.0 pm, a = 76.4°, β = 88.4°, γ = 73.5°). Although the crystal structures of the three sulfates are not isotypic they show similar structural features: The gold atoms are coordinated by four oxygen atoms in a square planar manner. These oxygen atoms belong to four SO4 2- ions which link the [AUO4] units to infinite chains according to 1 ∞[Au(SO4)4/ 2]- . These chains are connected via the monovalent cations which show coordination numbers of 6 (Na+), 10 (K+) and 12 (Rb+), respectively.

Cu1,45Er0,85S2: Ein Kupfer(I)-Erbium(III)-Sulfid mit kationendefekter CaAl2Si2-Struktur

Cu1.45Er0.85S2: A Copper(I) Erbium(III) Sulfide with Cation-Deficient CaAl2Si2-Type Structure Attempts to synthesize single-phase CuYS2-type copper(I) erbium(III) disulfide (CuErS2) from 1 : 1 : 2-molar mixtures of the elements (Cu, Er and S) after seven days at 900 °C in sealed evacuated silica tubes failed with equimolar amounts of CsCl working as flux and reagent. In these cases, quaternary CsCu3Er2S5 (orthorhombic, Cmcm; a = 394.82(4), b = 1410.9(1), c = 1667.2(2) pm, Z = 4) and ternary Cu1.45Er0.85S2 (trigonal, P3m1; a = 389.51(4), c = 627.14(6) pm, Z = 1) become the unexpected by-products. Both emerge even as yellow single crystals (lath-shaped fibres and platelets, respectively, with triangular cross-section) and both crystal structures contain condensed [CuS4] and [ErS6] units as dominating building blocks. The ternary sulfide Cu1.45Er0.85S2 exhibits CdI2-analogous layers {[(Er3+)(S2–)6/3]–} of edge-shared [ErS6] octahedra (d(Er–S) = 272 pm, 6 × ) which are piled up parallel (001) and interconnected by interstitial Cu+ cations in tetrahedral S2– coordination (d(Cu–S) = 236 pm, 1 × ; 240 pm, 3 × ). The latter thereby form anionic layers {([(Cu+)(S2–)4/4]–)2} as well, consisting of [CuS4] tetrahedra which share three cis-oriented edges. When the S2– anions arrange hexagonally closest-packed and the corresponding layers are symbolized with capital Roman letters, the Er3+ cations (small Roman) and the Cu+ cations (small Greek letters) reside layerwise alternatingly within half of the octahedral (Er3+) and tetrahedral (Cu+) voids according to … AcB αβ AcB αβ A … . Since both kinds of cations occupy only a certain percentage (Cu+: 72.6%, Er3+: 85.1%) of their regular positions, the crystal structure of Cu1.45Er0.85S2 can be addressed as a double cation-deficient CaAl2Si2-type arrangement according to (Er0.85□0.15)(Cu1.45□0.55)S2. The partial occupation could be established by both released site occupation factors in the course of the crystal structure refinement and electron beam X-ray microanalysis (EDX).

Trigonal prismatic vs octahedral coordination geometry: syntheses and structural characterization of hexakis(arylthiolato) zirconate complexes.

Treating [Li(tmeda)]2[Zr(CH3)6] with aryl thiols, HSC6H4-4-R, in a 1:6 stoichiometry in diethyl ether affords excellent yields of [Li(tmeda)]2[Zr(SC6H4-4-R)6], where R = CH3 (1(2-)) or OCH3 (2(2-)) and tmeda denotes N,N,N',N'-tetramethylethylenediamine. These complexes are air-sensitive canary-yellow solids, soluble in hexane, diethyl ether, THF, and acetonitrile, that form yellow single crystals of [Li(tmeda)](2)1 (diethyl ether solution) or [Li(THF)3](2)2 (THF solution) from saturated solutions at -20 degrees C. Both complexes were characterized by X-ray crystallography and consist of a zirconium atom coordinated solely by the sulfur atoms of six aryl thiolate ligands in a nonoctahedral geometry. In each structure the lithium cation coordinates to the three sulfur atoms on the triangular faces of the S6 pseudotrigonal prism. These lithium-sulfur interactions appear to play a role in determining the coordination geometry about the metal center by orienting the sulfur lone pairs of electrons slightly out of the plane defined by the S3 triangular face and tilted away from the zirconium atoms. A likely consequence is the positioning of the sulfur lone pairs of electrons away from orthogonality with the zirconium-sulfur vector, and hence, they are poorly arranged to pi-interact with zirconium. Complex 1(2-) with a twist angle of ca. 9.18 degrees (trigonal prism, 0 degree; octahedron, 60 degrees) agrees with the interpretations of computational studies on d degree complexes, which suggest that a nearly trigonal prismatic geometry is favored when the interaction between metal and ligand is primarily through sigma-bonds. The intrinsically weak pi-donor thiolate ligand is probably converted to a primarily sigma-bonding system by the lithium-sulfur interaction. On the other hand complex 2(2-) with a twist angle of ca. 30.38 degrees is trigonally twisted to the midpoint of the trigonal prismatic-to-octahedral reaction coordinate. In complex 2(2-) the 4-OCH3 group is an electron donor by resonance effects that possibly may lead to the movement away from the expected trigonal prismatic geometry due to either pi-interactions or electrostatics repulsion.

Dimers [Al2N6]12- and Chains 1 ∞[AlN4/2 3-] in the Crystal Structures of Ca6[Al2N6] and Ba3[Al2N4

Pale yellow transparent single crystals of Ca6[Al2N6] (P21/c, No. 14, a = 693.7(3), b = 614.9(3), c = 987.1(5) pm, ß = 94.01(5)°; Z = 4) and colourless transparent single crystals of Ba3[Al2N4] (Pnna, No. 52, a = 617.9(2), b = 1005.2(4), c = 1023.0(4) pm; Z = 4) were obtained from reactions of mixtures of the representative metals with nitrogen at Tmax = 1000 °C. The crystal structure of Ca6[Al2N6] contains isolated units [Al2N6]12- built of two edge-sharing tetrahedra. Ba3[Al2N4] is an isotype of Sr3[Al2N4]. The crystal structure contains infinite chains 1 ∞ [AlN4/2 3-] of trans edge-sharing tetrahedra.

Yb3OBr4{N(SiMe3)2}3 (THF)3], ein Amido‐Komplex des Ytterbiums mit clusterähnlichem Aufbau

[Yb3OBr4{N(SiMe3)2}3(THF)3], an Amido Complex of Ytterbium with a Clusterlike StructureThe title compound has been prepared from YbBr3 and NaN(SiMe3)2 in THF suspension, forming yellow single crystals from hexane solutions which were characterized by a crystal structure determination. Space group P1, Z = 2, lattice dimensions at −100°C: a = 1085.4(1), b = 1410.2(1), c = 1912.0(1) pm; α = 78.62(1)°, β = 80.61(1)°, γ = 73.45(1)°, R = 0.025.In the molecular structure of [Yb3OBr4{N(SiMe3)2}3(THF)3] the three ytterbium atoms together with the μ3‐oxygen atom and a μ3‐bromine atom form a distorted trigonal bipyramid. In addition, three μ2‐Br atoms coordinate the Yb atoms in the equatorial plane, whereas the THF molecules and the N(SiMe3)2− ligands are terminally coordinated, thus forming a distorted octahedrally surrounding of the Yb atoms.

(OLi 2Ca 4) 3[MN 4] 4 (MMo, W): nitridometalate oxides with close structural relationships to the Th 3P 4 type structure

Molybdenum and tungsten powder react readily with alkali and alkaline earth metal nitrides to form nitridometalates. Transparent yellow single crystals of the title compounds are formed in the presence of traces of oxides under flowing nitrogen at 850 °C/900 °C. The crystal structures were determined by single crystal X-ray analyses (space group l 43d, Z = 4 , (OLi 2Ca 4) 3[MoN 4] 4: a = 13.061(3) A ̊ , (OLi 2Ca 4) 3[WN 4] 4: a = 13.060(2) A ̊ ). Predominant structural features are isolated tetrahedral complex anions [MoN 4] 6− and [WN 4] 6−, which can be described in accordance with the extended Zintl-Klemm concept. The isolated oxygen atoms are surrounded by four Ca and two Li cations in a tetragonal bipyramidal arrangement with Ca forming the tetragonal basis. The centers of tetrahedra and tetragonal bipyramids form a pattern which resembles the motif of the Th 3P 4 type structure.

Die Kristallstruktur von [Mn(CH3CN)6][MnI4

Abstract [Mn(CH3CN)6][MnI4] crystallizes from acetonitrile solutions of Mnl2 as yellow single crystals which were characterized by their IR spectrum and by a crystal-structure analysis. Space group P21/n, Z = 4, structure solution with 3742 observed unique reflections with Fo >5σ(Fo), R = 0.050. Lattice dim ensions at 20°C: a = 1258.0(5), b = 1244.7(2), c = 1753.3(6) pm, β = 92.22(3)°. The compound forms octahedral cations [Mn(CH3CN)6]2+ with site symmetry Ci with average Mn-N bond lengths of 222.3 pm and te­trahedral anions [Mnl4]2- without symmetry with average bond lengths MnI of 271.3 pm.

Synthesis, Properties, and Crystal Structures of Benzene-1,2-dithiolato Complexes of Thallium(I) and -(III).

The syntheses, molecular structures and properties of homoleptic 1,2-S(2)C(6)H(4) complexes of thallium(I) and thallium(III) with four-coordinated metal centers are described. Anaerobic treatment of TlCl, TlNO(3), or Tl(2)CO(3) with solutions of sodium methanolate and 1,2-(HS)(2)C(6)H(4) in methanol gave after metathesis with [NEt(4)]Br yellow solutions of [NEt(4)](2)[{Tl(1,2-(&mgr;-S)(2)C(6)H(4))}(2)] ([NEt(4)](2)1). Yellow single crystals were obtained from saturated acetone solutions at -10 degrees C and the crystal data for [NEt(4)](2)1 are monoclinic, P2(1)/c, with Z = 2, a = 7.440(1) Å, b = 16.373(3) Å, c = 13.201(2) Å, and beta = 97.08(1) degrees. Complex 1(2)(-)(), the first structurally characterized homoleptic ionic thiolate complex of thallium(I), contains rectangular bipyramidal [TlS(4)Tl] cages with the four sulfur atoms defining the equatorial plane and the two thallium atoms in axial positions. The S(2)C(6)H(4) fragments are almost coplanar with the S(4) plane. In the crystal lattice, nearly linear Tl.Tl chains align along the a-axis (offset ca. 3.0 degrees ) with the ligand planes parallel to the bc-plane. Within and between dimers short Tl.Tl distances are observed (Tl.Tl' within a dimeric unit, 3.5116(4) Å; Tl.Tl between dimeric units, 3.9371(3) Å) with the distance between dimeric units being the shortest contact between anions-Tl.S distances between dimeric units are longer than 5.8 Å. Aerobic treatment of TlCl, TlNO(3), or Tl(2)CO(3) with solutions of sodium methanolate and 1,2-(HS)(2)C(6)H(4) in methanol and metathesis with [NEt(4)]Br led to [NEt(4)][Tl(1,2-S(2)C(6)H(4))(2)] ([NEt(4)]2). Yellow single crystals were obtained from saturated acetone solutions at 0 degrees C and the crystal data for [NEt(4)]2 are orthorhombic, Pnn2, with Z = 2, a = 11.449(2) Å, b = 10.060(2) Å, c = 9.950(2) Å. Complex 2(-) is the first homoleptic four-coordinate thiolate of thallium(III) and contains the unusually short Tl-S distance of 2.469(4) Å. In solution, ion pairing results in chemical and magnetic inequivalence of the S(2)C(6)H(4) ligands. Although both preparations employ the reaction of thallium(I) salts with 1,2-(NaS)(2)C(6)H(4) in a 1:2 stoichiometry, complex 1(2)(-) is probably not an intermediate to the formation of 2(-). Exposing anaerobically prepared solutions of 1(2)(-) to air results in a series of color changes in the solution over a 20 min period; however, 2(-) could not be observed by NMR spectroscopy.

Synthesis, properties and crystal structures of benzene-1,2-dithiolato complexes of antimony-(III) and -(V)

Anaerobic treatment of SbCl3 with 1,2-(LiS)2C6H4 provided a reliable route to [Sb(1,2-S2C6H4)2]– which in turn produced [Sb(1,2-S2C6H4)3]– on reaction with 1,2-(HS)2C6H4 and O2 in very good yields ([NEt4]+ salt, ca. 82%). Tetraalkylammonium salts of [Sb(1,2-S2C6H4)2]– were isolated after metathesis with either [NEt4]Br ([NEt4]+ salt, ca. 72%) or [NBun4]l ([NBun4]+ salt, ca. 90%). Slowly cooling hot MeCN solutions of [Net4][Sb(1,2-S2C6H4)2] gave yellow single crystals. This compound is the first structurally characterized anionic thiolate complex of SbIII. In its structure the stereochemical influence of the lone pair of electrons leads to a distorted Ψ-trigonal-bipyramidal environment [Sax–Sb–Sax 158.95(3), Seq–Sb–Seq 105.08(3)°], however, the degree of distortion is less severe than expected for a complex with a normalized bite (b) of 1.31. Dark purple single crystals of [NEt4][Sb(1,2-S2C6H4)3] were obtained by slowly cooling hot MeCN–MeOH solutions. The co-ordination geometry about Sb is slightly distorted from octahedral with a twist angle of 49.22(3)° and most structural parameters are within 10% of octahedral values.

Synthesis and structure of a potassium nitridoditungstenate (K 6W 2N 4O 3), a potassium digermanate (K 6Ge 2O 7) and a rubidium digermanate (Rb 6Ge 2O 7)

Light yellow single crystals of potassium nitridoditungstate (K 6W 2N 4O 3) and pale single crystals of potassium digermanate (K 6Ge 2O 7) were obtained by the reaction of the metal oxides WO 3 (molar ratio, 1 : 15.7) or GeO 2 (molar ratio, 1 : 2) in alkali metal amide melts in an autoclave at 530–600 °C for 6–8 days. Colourless single crystals of rubidium digermanate (Rb 6Ge 2O 7) were prepared by the reaction of GeO 2 with rubidium amide (molar ratio, 1 : 2) in ammonia at 350 °C in a high-pressure autoclave (H. Jacobs and D. Schmidt, in E. Kaldis (ed.), High-pressure Ammonolysis in Solid State Chemistry, Current Topics in Materials Science, Vol. 8, North Holland, Amsterdam, 1981, p. 379) ( p( NH 3) = 5.5 kbar) for 10 days. In all three cases other nitrogen-containing products were present. The structures of the title compounds were determined on the basis of single-crystal data. They are isotypic or structurally closely related to each other: K 6W 2N 4O 3: P2 1/ n, a = 6.720(2) A ̊ , b = 9.473(1) A ̊ , c = 9.581(2) A ̊ , β = 91.99(2)°, Z = 2, R/ R w = 0.040/0.048, N( I) > 3 σ( I) ⩾ 2057, N(Var.) = 71. K 6Ge 2O 7: Pn, a = 6.529(2) A ̊ , b = 9.079(4) A ̊ , c = 9.162(6) A ̊ , β = 91.85(4)°, Z = 2, R/ R w = 0.022/0.024, N( I) ⩾ 3 σ( I) = 1486, N(Var.) = 135. Rb 6Ge 2O 7: P2 1/ n, a = 6.839(4) A ̊ , b = 9.437(6) A ̊ , c = 9.460(6) A ̊ , β = 91.53(5)°, Z = 2, R/ R w = 0.061/0.074, N( I) ⩾ 3 σ( I) = 1055, N(Var.) = 71.

Na4SnSe4 und K4SnSe4, zwei neue Selenostannate mit isolierten Anionen / Na4SnSe4 and K4SnSe4, Two New Selenostannates with Discrete Anions

Abstract Transparent yellow single crystals of Na4SnSe4 and K4SnSe4 were prepared by reacting stoichiometric powdered mixtures of the binary compounds Na2Se or K2Se, Sn and Se at 850 K. Na4SnSe4 is tetragonal, s.g. P4̄21c, with a = 8.165(2) Å, c = 7.268(2) Å, Z = 2. K4SnSe4 is orthorhombic, s.g. Pnma, with a = 14.714(7) Å, b = 10.323(3) Å, c = 8.248(6) Å, Z = 4. The crystal structures were refined to conventional residuals of 0.058 and 0.031, respectively. Both com pounds are characterized as salts with discrete tetrahedral selenostannate anions. Na4SnSe4 is isostructural with Na4SnS4, K4SnSe4 is of a new type. The observed Sn -Se bond lengths range from 2.494 Å to 2.536 Å.

Structure of 1,1'-bis(diphenylphosphinotetramethyl)ferrocene

Fe(C21H22P)2), Mr = 666.61, triclinic, Pi, a = 7.698 (3), b = 8.663 (2), c = 13.724 (4) A, a = 80-25 (2), fl = 83-58 (3), 3/= 75.69 (3) °, V = 871.6 A 3, Z = 1, D,, = 1.270 g cm -3, a(Mo Ka) = 071073/~, /z = 5-490 cm-1, F(000) = 352, T = 296 (1) K, R = 0.047 for 2712 reflections with I > 3.5o.(I). The title complex, a precursor for bi- or polymetallic com- pounds, bears a new bifunctional permethylated ligand which is more electron rich than the known diphenylphosphinecyclopentadienyl moiety. The geometry of the complex is affected little by the substitution of methyl groups for H atoms in the tings. The molecule is centrosymmetric with the Fe atom at the crystallographic inversion centre. Experimental. The compound was synthesized by reaction of FeC12 with CsMe4PPh2Li in THF. Recrystallization from CHC13/pentane afforded yellow single crystals. A specimen (0.08 x 0.08 x 0.15 mm) was mounted on an Enraf-Nonius CAD-4 diffractometer. The unit cell was determined and refined from angle data of 25 randomly seiected reflections in the range 11 < 0 < 19 ° (CAD-4 rou-

ChemInform Abstract: On the KAgO Structure. Reinvestigation of AAgO = A4(Ag4O4) (A: Na‐Rb). With a Note on CsCuO and New Calculations on A4(M4O4) (A: Li‐Rb with M: Cu and A: Cs with M: Ag).

AbstractSlightly yellow single crystals of KAgO are obtained by annealing intimate mixtures of K2O and KMnO4 in a Ag tube (K:Mn = 7.8:1; 7 d, 800 °C; 35 d, 600 °C) as a result of a reaction with the wall.

Fire retardant polycarbonate sheet

Chalcone derivatives are simple chemical scaffold found in natural products and have been extensively used as an effective template in medicinal chemistry for drug discovery. Two new geometrical isomers of 1-(5-bromothiophen-2-yl)-3-(10-chloroanthracen-9-yl)prop-2-en-1-one were synthesized, isolated and characterized by various spectroscopic techniques (FT-IR, NMR, LC-MS and UV-visible). Two different shaped (cis and trans) yellow colored single crystals were obtained by slow evaporation method and the molecular structures were confirmed by X-ray diffraction studies. The cis configuration crystallizes in the monoclinic P21/c space group, whereas, trans configuration crystallizes in the orthorhombic P212121 space group. The conformational changes lead to variations in molecular packing arrangement. In cis, 2-D layer-like architecture is constructed by C-H…O and S…S contacts, whereas, in trans 3-D zig-zag pattern is generated by C-H…O, C-H…Cl and Br…π interactions. The unique supramolecular topology of the isomers established by diverse intra and intermolecular interactions was analysed by Hirshfeld surfaces, 2D fingerprint plots, 3D energy framework and NCI index model. The Frontier molecular orbitals explored HOMO-LUMO energy gap and associated electronic properties were calculated. The molecular electrostatic potential (MEP) was plotted to identify the reactive sites in the molecule.

ChemInform Abstract: “LaTa5O14”, a Derivative of the Tetragonal Tungsten Bronzes. Preparation and Structure.

AbstractPale yellow single crystals of the title compound are obtained for the first time by annealing intimate mixtures of La2O3 and Ta2O5 (1:5, Pt crucible; 1. 1600 °C, 3 d; 2. 1685 °C, 5 d, in the air).