Congruent Melting Compound Research Articles

Ag3Ga3SiSe8: a new infrared nonlinear optical material with a chalcopyrite structure

An infrared (IR) nonlinear optical (NLO) material, Ag3Ga3SiSe8, has been synthesized for the first time. It crystallizes in the tetragonal chalcopyrite AgGaSe2 structure type and the substitution of Ga3+ with Si4+ generates an equal amount of vacancies at the Ag+ position. Ag3Ga3SiSe8 is a congruent melting compound with a melting temperature of 784 °C. The second-harmonic generation (SHG) effect of Ag3Ga3SiSe8 is similar to that of AgGaSe2, as confirmed by the first-principles studies. Moreover, the diffuse reflectance spectra reveal that the energy band gap of Ag3Ga3SiSe is 2.30 eV, 0.44 eV larger compared with AgGaSe2 (1.86 eV). The birefringence of Ag3Ga3SiSe8 is predicted to be above 0.1 at the wavelength of 1 μm, significantly larger than that of AgGaSe2 (Δn ~ 0.02). Our results indicate that Ag3Ga3SiSe8 may possess improved optical properties compared with AgGaSe2 and has a promising application as a good IR NLO material.

Synthesis, Crystal Structure, and Characterization of a ­Congruent Melting Compound Magnesium Strontium Diborate MgSrB2O5

Abstract A congruent melting compound MgSrB2O5 was synthesized by high temperature solution method from the MgO‐SrO‐B2O3 system, and the structure was determined by single‐crystal X‐ray diffraction methods. The compound crystallizes in the monoclinic system, with space group P21/c. The crystal structure is composed of isolated B2O5 units and MgO6 octahedra that are connected to form two‐dimensional [Mg2B4O10] layers stacking along the c axis. The layers are bridged by the Sr2+ cations to form a three‐dimensional framework. The IR spectrum and the thermal properties of MgSrB2O5 were also reported. Additionally, detailed structure comparisons between MgSrB2O5 and other borates, such as Mg2B2O5, Sr2B2O5 and SrCdB2O5 are carried out and the first‐principle theoretical studies are performed to aid the understanding of electronic structures and linear optical properties.

Floating zone crystal growth of Lu2PdSi3 silicide

Lu2PdSi3 crystals have been grown by the floating zone method with optical heating. The congruently melting compound is a non-magnetic member of the class of R2PdSi3 intermetallics (R: rare earths) with hexagonal AlB2-type crystallographic structure. The grown crystals are slightly Pd-depleted with respect to the nominal stoichiometry and contain a minor fraction of LuSi binary phase precipitates. Lu2PdSi3 exhibits normal metallic behavior, but its electrical resistivity is highly anisotropic and deviates from the Bloch–Grüneisen law.

A new technique to grow incongruent melting Ga:YIG crystals: the edge-defined film-fed growth method

Crystalline yttrium iron garnet (YIG) is an important magneto-optical material. However, this crystal is an incongruent melting compound. As is well known, compared to the crystal growth of a congruent melting compound by using the Czochralski method, the crystal growth of an incongruent melting compound is more difficult. In this work, a system for growing Ga:YIG single crystals by the edge-defined film-fed growth (EFG) method was designed and constructed, and the mechanism of crystal growth was also preliminarily studied. The Ga3+dopant concentration, the Curie temperature and the transmission spectra of as-grown crystals were investigated to evaluate their potential application in magneto-optical devices. The success of growing Ga:YIG crystals by the EFG method provides a new way to grow other incongruent melting compounds.

ChemInform Abstract: Synthesis, Crystal Structure and Properties of a New Congruently Melting Compound, K3ZnB5O10.

AbstractThe new title compound is synthesized by solid state reaction of a stoichiometric mixture of ZnO, K2CO3, and H3BO3 (Pt crucible, 600 °C, 48 h).

Phase relations in the aluminothermic reduction of ZrO2

This paper presents thermodynamic evaluation of reactions between ZrO2 and aluminum, which indicates that the aluminothermic reduction of zirconium oxides at temperatures above 600°C is only possible when AlxZry intermetallic compounds form in the metallic phase. Thermodynamic analysis results are supported by experimental data, which demonstrate that, at ZrO2: Al ratios in the range 0.4–1.4, the aluminothermic reduction of ZrO2 leads predominantly to the formation of the congruently melting compounds Al2Zr and Al3Zr. The phase formation in the slag yields various forms of calcium aluminates and calcium zirconates and leads to a gradual reduction in the oxidation state of the zirconium.

Synthesis, crystal structure and properties of a new congruently melting compound, K3ZnB5O10

A new compound, K3ZnB5O10, has been synthesized by solid-state reaction. It crystallizes in the monoclinic system, space group P21/n with unit–cell parameters a = 7.6391(5) Å, b = 19.2304(13) Å, c = 7.6905(5) Å, β = 116.698(4)° and Z = 4. The structure of the compound is solved by the direct methods and refined to R1 = 0.0286 and wR2 = 0.0600. K3ZnB5O10 contains a two-dimensional ZnB5O10 layer, which forms by connecting isolated double ring [B5O10] groups and ZnO4 tetrahedra. The K atoms filling in the interlayer and intralayer link the layers together. Functional groups presented in the sample were identified by FTIR spectrum. UV–vis–NIR diffuse reflectance spectrum exhibits ultraviolet cutoff edge is about 190 nm. The DSC analysis proves that K3ZnB5O10 is a congruently melting compound.

Li5Rb2B7O14: a new congruently melting compound with two kinds of B–O one-dimensional chains and short UV absorption edge

A new non-centrosymmetric polyborate, Li5Rb2B7O14, has been synthesized. The structure of the title compound was solved by single-crystal X-ray diffraction analysis. The infinite three-dimensional structure of Li5Rb2B7O14 is constructed from bridged LiOn (n = 4, 5, 6) and RbO10 polyhedra with two kinds of one-dimensional B–O chain fundamental building blocks through their vertex oxygen atoms. It melts congruently and exhibits a short-wavelength absorption onset at 190 nm. The feature of a short UV cut off edge is favourable in practical applications. The calculated band structure and the density of states of Li5Rb2B7O14 suggest that its indirect energy gap is 4.247 eV. The materials have also been characterized by infrared spectroscopy and thermal analysis.

Thermodynamic properties of potassium nitrate–magnesium nitrate compound [2KNO3·Mg(NO3)2

The Mg(NO3)2–KNO3 binary system phase diagram has a congruent melting compound, 2KNO3·Mg(NO3)2. The thermodynamic properties for this compound are not available in the literature. In this study, the nitrate compound was synthesized and the melting point and heat capacity were determined using differential scanning calorimetry (DSC). Two endothermic peaks were observed at 404.8K and 468.83K corresponding to solid state transition and melting of the compound with the enthalpies of transitions as 2.71kJ/mol and 20.73kJ/mol, respectively. The heat capacity data as function of temperature are fit to polynomial function and thermodynamic properties like enthalpy, entropy and Gibbs energies of the compound as function of temperature are subsequently deduced.

Synthesis, structure characterization and optical properties of a new tripotassium cadmium pentaborate, K 3CdB 5O 10

A new ternary borate oxide, K 3CdB 5O 10, has been synthesized by solid-state reaction at 580 °C. The compound crystallizes in the monoclinic space group P2 1/ n with a=7.6707 (7) Å, b=19.1765 (17) Å, c=7.8784 (6) Å, β=115.6083 (49)°, and Z=4. The crystal structure consists of a two-dimensional infinite [CdB 5O 10] layer, which forms by connecting isolated double ring [B 5O 10] groups and CdO 4 tetrahedra. K atoms filling in the interlayer and intralayer link the layers together and balance charge. The IR spectrum has been studied and confirmed the presence of both BO 3 and BO 4 groups, and the UV–vis-IR diffuse reflectance spectrum exhibits a band gap of about 3.4 eV. The DSC analysis proves that K 3CdB 5O 10 is a congruent melting compound.

Crystal structure and Eu 3+/Tb 3+ doped luminescent properties of a new borate Ba 3BiB 9O 18

Undoped and doped either by Eu 3+ or Tb 3+ bismuth borate Ba 3BiB 9O 18 was structurally characterized and analyzed by fluorescence spectroscopy. Belonging to synthetic borate member of the family Ba 3XB 9O 18, layers of planar triangular B 3O 6 groups connecting with deformed BaO 6 hexagons are interleaved by 9-coordinate Ba atoms, and 6-coordinate Bi atoms. Its crystal structure was determined and refined from powder X-ray diffraction data by the Rietveld method and the results showed that Ba 3BiB 9O 18 belongs to space group P6 3/ m with unit cell dimensions of a = 7.1999(2) Å, c = 17.3567(6) Å, and z = 2. Curves of differential thermal analysis and thermogravimetric analysis showed that Ba 3BiB 9O 18 is a congruent melting compound and chemically stable above 728 °C. Ba 3Bi 1− x Eu x B 9O 18 and Ba 3Bi 1− x Tb x B 9O 18 form a continuous solid solution from x = 0.01 to x = 0.9. The ultraviolet excited photoluminescence intensity increased with both Eu 3+ and Tb 3+ concentration in the matrix of Ba 3BiB 9O 18. There may be an interesting correlation between spectroscopic properties and lattice structural features of doped Ba 3BiB 9O 18.

A Novel Nonlinear Optical Crystal Bi2ZnOB2O6

Sizable single crystals of a nonlinear optical (NLO) material, Bi2ZnOB2O6, were grown by the Kyropoulos method from stoichiometric ratio compound melt. It is a congruent melting compound and crystallizes in the orthorhombic system, space group Pba2. The morphologies and habits of Bi2ZnOB2O6 crystals grown using [100], [010], and [001] seeds were studied. The SHG efficiency of Bi2ZnOB2O6 is 3−4 times that of KDP (KH2PO4). Its birefringence is pretty large (0.085−0.106). The experiments prove that Bi2ZnOB2O6 crystal is nonhygroscopic and excellently deliquescence resistant.

Melting in the Fe–C system to 70 GPa

We determined high-pressure melting curves for Fe 3C, Fe 7C 3 and the Fe–Fe 3C eutectic using laser-heated diamond anvil cell techniques. The principal criterion for melting is the observation of plateaus in the temperature vs. laser power function, which is an expected behavior at isobaric invariant points (e.g. congruent, eutectic, or peritectic melting) as increased power provides the latent heat of melting. We verified this technique by reproducing the melting curves of well-studied congruently melting compounds at high pressure (Fe, Pt, FeS, Pb), and by comparison with melting determinations made using thermocouple-based large-volume press techniques. The incongruent melting curve of Fe 3C measured to 70 GPa has an apparent change in slope at ~ 8 GPa, which we attribute to stabilization of Fe 7C 3 at the solidus and the creation of a P– T invariant point. We observe that Fe 7C 3 melts at higher temperatures than Fe 3C between 14 and 52 GPa and has a steep P– T slope, and on this basis predicts an expanding field of Fe 7C 3 + liquid with pressure. The Fe–Fe 3C eutectic melting curve measured to 70 GPa agrees closely with multi-anvil data and thermodynamic calculations. We also measured the eutectic composition as a function of pressure using an in situ X-radiographic imaging technique, and find a rapid drop in carbon in the eutectic composition above about 20 GPa, generally consistent with previous thermodynamic calculations, and predict that the eutectic lies close to pure iron by ~ 50 GPa. We use these observations to extrapolate phase relations to core-relevant pressures. Convergence of the Fe 3C and Fe–Fe 3C eutectic melting curves indicate that Fe 3C is replaced at the solidus by Fe 7C 3 at ~ 120 GPa, forming another P– T invariant point and a new eutectic between Fe and Fe 7C 3. Thus, Fe 3C is unlikely to be an important crystallizing phase at core conditions, whereas Fe 7C 3 could become an important crystallizing phase.

Join Si-ZnAs2 of the ternary system Zn-Si-As

The quasi-binary join Si-ZnAs2 of the system Zn-Si-As was studied by physicochemical methods. The congruently melting compound ZnSiAs2 and eutectics Si + ZnSiAs2 and ZnSiAs2 + ZnAs2 are formed along this join. The composition of the eutectic Si + ZnSiAs2 is 90 mol % ZnAs2 and 10 mol % Si; T m = 630°C. The composition of the eutectic ZnSiAs2 + Si is 55 mol % Si and 45 mol % ZnAs2. The component solubilities in ZnSiAs2 do not exceed 1 mol %.

A new promising scintillator Ba 3InB 9O 18

We report on the synthesis, crystal structure and scintillation property of a new compound Ba 3InB 9O 18. This compound crystallizes in space group P6 3/ m with unit cell of dimensions a=7.1359(3) Å, c=16.6151(8) Å and V=732.697 Å 3 with two Ba 3InB 9O 18 molecular formula. Its crystal structure is made up of planar B 3O 6 groups parallel to each other along the 〈0001〉 direction, regular InO 6 octahedra, irregular BaO 6 hexagons and BaO 9 polyhedra to form an analog structure of Ba 3YB 9O 18. DTA and TGA curves for Ba 3InB 9O 18 show that it is a chemically stable and congruent melting compound. Its X-ray excited luminescence spectra show an intense emission band in the range of 360–500 nm with a maximum at 400 nm. Light yield for Ba 3InB 9O 18 is about 75% as large as that for BGO under the same measurement conditions. There may exist a correlation between the scintillation properties and the crystal structural features of Ba 3InB 9O 18.

Crystal structure and luminescence properties of a novel promising phosphor Ba3ScB9O18

A novel borate compound Ba3ScB9O18 has been synthesized by solid-state reaction and its structure has been determined and refined from powder X-ray diffraction data. This compound crystallizes in a hexagonal cell (space group P63/m) with lattice parameters a=7.1360(4) Å and c=16.5420(9) Å, and each unit cell contains two formulas. Its crystal structure is made up of planar B3O6 groups parallel to each other along the [001] direction, regular ScO6 octahedra, irregular BaO6 hexagons, and BaO9 polyhedra to form an analogue structure of Ba3YB9O18. DTA and TGA curves for Ba3ScB9O18 show that it is a chemically stable and congruent melting compound. Luminescence properties for Ba3ScB9O18 were investigated using fluorescence spectroscopy and X-ray excited luminescence measurements. Its emission spectrum upon UV excitation (330 nm) has exhibited a prominent blue-green emission band at about 490 nm, and its XEL spectra show an intense emission band in the range of 360 to 500 nm with peak center at 400 nm. The light yield of Ba3ScB9O18 powders is about 23% as large as that of BGO powders under the same measurement conditions. There seems to be a certain relationship between the scintillation properties and the structural features of Ba3ScB9O18.

Thermodynamic study of the BiCl3-MCl (M = Li, Na, K, Cs) systems in the ideal associated solution model

The thermal stability of the congruently melting compounds LiCl · BiCl3, LiCl · 4BiCl3, NaCl · BiCl3, 3KCl · BiCl3, and 3CsCl · BiCl3 is assessed from the curvature of the liquidus at their melting points, and the applicability of the ideal associated solution model to the BiCl3-LiCl, BiCl3-NaCl, BiCl3-KCl, and BiCl3-CsCl systems is analyzed.

Thermodynamic Functions of Congruently Melting Compounds Formed in the CeBr3−KBr Binary System

The heat capacity of the congruently melting compounds K2CeBr5 and K3CeBr6 was measured by differential scanning calorimetry in the temperature range from 400 K up to 1100 K. A linear heat capacity dependence on temperature was used to fit the experimental data. Through combination of these results with the entropy at 298.15 K, and enthalpies of phase transitions, the thermodynamic functions of K2CeBr5 and K3CeBr6 were calculated up to T = 1100 K.

Solubility and solid phases in the systems zinc nitrate-dimethylcarbamide-water and cadmium nitrate-dimethylcarbamide-water at 25°C

Solubility isotherms have been studied in the systems Zn(NO3)2-(CH3)2NCONH2-H2O and Cd(NO3)2-(CH3)2NCONH2-H2O at 25°C. Crystallization fields have been determined for the congruent-melting compounds Zn(NO3)2 · 4(CH3)2NCONH2 · 2H2O (I) and Cd(NO3)2NCONH2 (II). The compounds have been characterized by chemical analysis, differential thermal analysis, powder X-ray diffraction, and IR spectroscopy.

Experimental (solid + liquid) phase equilibria of (alkan-1-ol + benzonitrile), (amine + benzonitrile) binary mixtures, and (decan-1-ol + decylamine + benzonitrile) ternary mixtures

(Solid + liquid) phase diagrams, SLE have been determined for (octan-1-ol, or nonan-1-ol, or decan-1-ol, or undecan-1-ol + benzonitrile) and for (hexylamine, or octylamine, or decylamine, or 1,3-diaminopropane + benzonitrile) using a cryometric dynamic method at atmospheric pressure. Simple eutectic systems with complete immiscibility in the solid phase and complete miscibility on the liquid phase have been observed. The solubility decreases with an increase of the number of carbon atoms in the alkan-1-ol, or amine chain. The temperature of the eutectic points increases and shifts to lower alkan-1-ol, or amine mole fractions as the alkyl chain length of the alkan-1-ol, or amine increases. The higher intermolecular interaction was observed for the (alkan-1-ol + benzonitrile) systems. The experimental solubility results are compared with values calculated by means of the NRTL equation utilizing parameters derived from the SLE results. The existence of a solid–solid first order phase transition in undecan-1-ol has been taken into consideration in the calculations. The correlation of the solubility data has been obtained with the average root-mean-square deviation σ < 1.0 K. (Solid–liquid) equilibria, for the ternary system (decylamine + decan-1-ol + benzonitrile) have been determined at three temperatures 273.15, 278.15 and 283.15 K using the same cryometric dynamic method at atmospheric pressure. The experimental results show the existence of a solid addition compound with the empirical formulae: C 10H 23N·C 10H 21OH. This compound is congruently melting compound. The addition of benzonitrile to the binary system causes a lowering of the melting temperature of the congruently melting compound.