Synthesis and x-ray diffraction study of new nanostructured manganite ferrites NdM 1.5 II MnFeO6 (MII = Mg, Ca, Sr, Ba)

Manganite ferrites NdM _1.5 ^II MnFeO₆ (M^II = Mg, Ca, Sr, Ba) were synthesized from neodymium(III), manganese(III), and iron(III) oxides and alkaline-earth metal carbonates by a ceramic technology. By grinding the obtained compounds in a ball mill, their nanostructured particles were produced, the sizes of which were determined with an electron microscope. X-ray diffraction study established that the nanostructured compounds crystallize in the cubic and tetragonal systems with the following lattice parameters: NdMg_1.5MnFeO₆ (tetragonal): a = 10.955 Å, c = 17.848 Å, V ⁰ = 2141.975 ų, Z = 16, V _e1.cel1 ⁰ = 133.873 ų, ρ_X-ray = 4.80 g/cm³, and ρ_pycn = 4.76 ± 0.05 g/cm³; NdCa_1.5MnFeO₆ (cubic): a= 10.809 Å, V ⁰ = 1262.864 ų, Z = 8, V _e1.cel1 ⁰ = 157.858 ų, ρ_X-ray = 4.32 g/cm³, and ρ_pycn = 4.27 ± 0.03 g/cm³; NdSr_1.5MnFeO₆ (cubic): a = 10.911 Å, V ⁰ = 1298.953 ų, Z = 8, V _e1.cel1 ⁰ = 162.369 ų, ρ_X-ray = 4.93 g/cm³, and ρ_pycn= 4.88 ± 0.05 g/cm³; and NdBa_1.5MnFeO₆ (tetragonal): a = 11.011 Å, c = 18.001 Å, V ₀ = 2182.479 ų, Z = 16, V _e1.cel1 ⁰ = 136.405 ų, ρ_X-ray = 6.78 g/cm³, and ρ_pycn= 6.75 ± 0.07 g/cm³.     

Synthesis and X-ray diffraction study of nanostructured particles of cuprate manganites LaM 2 II CuMnO6 (MII = Mg,Ca, Sr,Ba)

Cuprate manganites of the composition LaM ₂ ^II CuMnO₆ (M^II = Mg, Ca, Sr, Ba) were synthesized from lanthanum, copper(II), and manganese(III) oxides and alkaline-earth metal carbonates by high-temperature solid-phase synthesis. By grinding the produced substances in a ball mill, their nanostructured particles were obtained, the sizes of which were determined with an electron microscope. Indexing the X-ray powder diffraction patterns of the cuprate manganites established that all of them crystallize in the cubic system with the following unit cell parameters: LaMg₂CuMnO₆: a = 15.523 ± 0.033 Å, Z = 6, V ⁰ = 3740.48 ± 0.10 ų, V _el.cell ⁰ = 623.41 ± 0.03ų, ρ_X-ray = 5.81 g/cm³, and ρ_pycn = 5.75 ± 0.06 g/cm³; LaCa₂CuMnO₆: a = 15.422 ± 0.058 Å, Z = 4, V ⁰ = 3667.94 ± 0.174 ų, V _el.cell ⁰ = 916.48 ± 0.04 ų, ρ_X-ray = 3.77 g/cm³, and ρ_pycn = 3.72 ± 0.05 g/cm³; LaSr₂CuMnO₆: a = 15.275 ± 0.049 Å, Z = 4, V ⁰ = 3564.05 ± 0.27 ų, V _el.cell ⁰ = 891.01 ± 0.07 ų, ρ_X-ray = 4.31 g/cm³, and ρ_pycn = 4.25 ± 0.05 g/cm³; and LaBa₂CuMnO₆: a = 15.589 ± 0.029 Å, Z = 4, V ⁰ = 3788.39 ± 0.09 ų, V _el.cell ⁰ = 947.10 ± 0.02 ų, ρ_X-ray = 4.74 g/cm³, and ρ_pycn = 4.70 ± 0.05 g/cm³. The data of an IR spectroscopic study of the cuprate manganites were presented.     

X-ray diffraction characteristics of new chromitomanganites LaM 3 I CrMnO6 and LaM 3 II CrMnO7.5 (MI = Li, Na; MII = Mg, Ca)

LaM ₃ ^I CrMnO₆ (M^I = Li, Na) and LaM ₃ ^II CrMnO_7.5 (M^II = Mg, Ca) chromitomanganites were synthesized by ceramic technology from lanthanum oxide, chromium(III) oxide, manganese(III) oxide, lithium carbonate, sodium carbonate, magnesium carbonate, and calcium carbonate. X-ray powder diffraction shows that these compounds crystallize in cubic or tetragonal systems with the following unit cell parameters: for LaLi₃CrMnO₆ (cubic): a = 10.98 Å, V ^○ = 1323.75 ų, Z = 8, V _u.c ^○ = 165.47ų, ρ_X = 3.64, ρ_pycn= 3.60 ± 0.04 g/cm³; for LaNa₃CrMnO₆ (tetragonal): a = 10.96 Å, c = 15.73 Å, V ^○ = 1889.51 ų, Z = 16, V _u.c ^○ = 118.09 ų, ρ_X = 5.77 g/cm³, ρ_pycn = 5.70 ± 0.07 g/cm³; LaMg₃CrMnO_7.5 (cubic), a = 10.98 Å, V ^○ = 1322.31 ų, Z = 8, V _u.c ^○ = 165.29 ų, ρ_X = 4.41 g/cm³, ρ_pycn = 4.35 ± 0.07 g/cm³; and for LaCa₃CrMnO_7.5 (cubic): a = 10.97 Å, V ^○ = 1319.78 ų, Z = 8, V _u.c ^pO = 164.97 ų, ρ_X = 4.89 g/cm³, ρ_pycn = 4.85 ± 0.05 g/cm³.     

Synthesis and X-ray diffraction study of Tm M 3 II Fe5O12 (MII = Ca, Sr, Ba) compounds

Double ferrites were synthesized by solid-phase annealing from thulium and iron oxides and alkaline-earth carbonates for the first time. Their symmetry systems and unit cell parameters were determined by X-ray diffraction analysis.     

Estimating the standard thermodynamic functions of rare-earth and alkali-earth manganitoferrites LnMIIMnFeO5.5 (Ln = La, Nd, Gd, Dy, Er; MII = Mg, Ca, Sr, Ba)

The standard enthalpies of formation of LnM^IIMnFeO^5.5 manganitoferrites (Ln is a rare-earth element, and M^II is an alkali-earth metal) were estimated by the developed method of calculation. Their standard entropies were calculated by the method of ionic increments, and their standard Gibbs energies of formation were determined by the Gibbs-Helmholtz equation.     

An IR and Raman study of trigonal triple molybdates M 5 I M 0.5 II Hf1.5(MoO4)6 (MI = K, Tl; MII = Ca, Sr, Ba, Pb)

The vibration spectra of triple molybdates M ₅ ^I M _0.5 ^II Hf_1.5(MoO₄)₆ (M^I = K, Tl; M^II = Ca, Sr, Ba, Pb) were examined. The internal vibration frequencies of molybdate groups were assigned. The double-charged cations affect the symmetric stretching (v₁), bending, and translation vibration frequencies in the Raman spectra. In the IR spectra, the triply degenerate stretching vibration of the MoO₄ group (～890–720 cm^?1) is split, and the splitting increases with an increase in the radius of the double-charged cation.     

X-ray diffraction study of ErMFe2O5.5 (M = Ca, Sr, Ba) double ferrites

Double ferrites ErCaFe₂O_5.5, ErSrFe₂O_5.5, and ErBaFe₂O_5.5 were synthesized by solid-state reactions from erbium and iron(III) oxides and calcium, strontium, and barium carbonates. The compounds were found to crystallize in the orthorhombic system. Their unit cell parameters were determined by X-ray powder diffraction; their densities were measured.     

Thermodynamic properties of ferrites of composition GdMIIFe2O5.5 (MII = Mg, Ca, Sr)

Ferrites with the composition GdM^IIFe₂O_5.5 (M^II = Mg, Ca, Sr) were synthesized from the corresponding oxides by the solid-phase method. The temperature dependence of the specific heat was studied by dynamic calorimetry in the temperature range 298.15 673 K. Equations describing this temperature dependence were derived. The temperature dependences of the thermodynamic functions were calculated.     

Synthesis and study of compounds of the general formula MIITh(VO4)2 (MII = Mn, Cd, Ca, Sr, Pb, or Ba)

Double vanadates of thorium and bivalent metals with r(M^II) ?? 0.96 ? were prepared by high-temperature solid-phase reactions. Manganese and barium derivatives were obtained for the first time. The compounds crystallize in three structural types: zircon for manganese, cadmium, calcium, strontium, and lead derivatives; scheelite for the lead phase; and monazite for the compounds containing lead and barium. Thus, two morphotropic transitions are observed in the series of the compounds studied; and for double thorium vanadates of lead, strontium, and barium, phase transitions are observed. The bands in the IR spectra were assigned. The incongruent melting points of the compounds were determined by differential scanning calorimetry. Compounds ??-PbTh(VO₄)₂ and BaTh(VO₄)₂ were studied by high-temperature X-ray diffraction.     

碱土金属钛酸盐-TiO2异质结型复合光催化活性研究

采用溶胶-凝胶法制备碱土金属钛酸盐MTiO3(M=Mg,Ca,Sr,Ba),并进一步与TiO2固相法复合制备MTiO3-TiO2异质结型复合光催化剂.以光催化降解亚甲基蓝(MB)为探针,评价了MTiO3和MTiO3-TiO2光催化剂的活性变化.结果表明,紫外光条件下碱土金属钛酸盐MTiO3的光催化活性顺序为:CaTiO3>BaTiO3>SrTiO3>MgTiO3,钙钛矿化合物的容忍因子、电负性以及催化剂的吸附性能都影响催化剂的降解效率.MTiO3与TiO2复合后形成的异质结复合光催化剂的催化活性得到显著的提高,催化剂浓度1.0g/L时,光催化反应1h后,MB(25mg/L)的降解率分别为82.6%,99.8%,93.7%,97.3%,异质结复合光催化剂活性顺序与MTiO3一致.光催化活性的提高与异质结界面形成电荷定向流动,促进光生电子、空穴的分离有关.     

Ce~（3＋）在钙钛矿型KMF_3（M＝Mg、Ca、Sr、Ba）基质中的发光特性

采用高温固相反应法，在Ａｒ气氛中合成了ＫＭＦ３（Ｍ＝Ｍｇ、Ｃａ、Ｓｒ、Ｂａ）基质化合物和掺杂Ｃｅ３＋的磷光体。经Ｘ射线衍射分析确定，ＫＭｇＦ３和ＫＣａＦ３属于立方晶系、钙钛矿型结构，ＫＳｒＦ３和ＫＢａＦ３具有类似的结构。测定了ＫＭＦ３∶Ｃｅ３＋的发光光谱，观察到与其结构对应的分为二种不同的光谱结构，讨论了Ｃｅ３＋的取代格位     

MIITiO(C2O4)2·4H2O (MII=Mg,Ca, Sr OR Ba) as precursors in the formation of MIITiO3 powders

A synthesis route is described for the preparation of the alkaline earth metal titanyl oxalates M^IITiO(C₂O₄)₂·4H₂O (M^II=Mg, Ca, Sr or Ba). The thermal decompositions of these compounds were studied by means of DTA and TG in comparison with X-ray measurements. The final products M^IITiO₃ were characterized morphologically.

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Zusammenfassung Ein Syntheseweg für die Darstellung der Erdalkalimetalltitanyloxalate M^IITiO(C₂O₄),·4H₂O (M ^II=Mg, Ca, Sr, Ba) wird beschrieben. Die thermische Zersetzung dieser Verbindungen wurde mittels DTA und TG sowie Röntgenbeugungsmethoden untersucht. Die entstehenden Titanate M^IITiO₃ wurden hinsichtlich ihrer morphologischen Eigenschaften charakterisiert.

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- MⁱⁱTiO(C₂O₄)₂ · 4₂, ⁱⁱ = , , . , . ⁱⁱiO₃, .

     

New ferrites of the composition TbM3 IIFe5O12 (MII = Ca, Sr, or Ba) and their XRD properties

For the first time double ferrites from terbium oxide, iron carbonates, and alkaline earth metals were synthesized using a solid phase procedure. Symmetry and unit cell parameters of the synthesized compounds were determined by X-ray diffraction method.     

Perovskite Distortion Inverted: Crystal Structures of (A3N)As (A = Mg,Ca, Sr,Ba)

Powder samples of the compounds (A₃N)As (A = Mg, Ca, Sr, Ba) were prepared by reacting the respective alkaline earth metal nitrides and arsenic in nickel ampoules. (Mg₃N)As crystallizes in a cubic unit cell (space group Pm3 m, no. 221) with inverse perovskite structure. The analogous compounds of calcium, strontium, and barium crystallize in an orthorhombic unit cell (space group Pnma, no. 62) as distorted inverse perovskites in the GdFeO₃ structure type. The degree of distortion was quantified based on a newly developed vectorial comparison of the atomic sites of coordination polyhedra with the ideal positions (PolyDis). Based on this analysis, the distortion increases with the size of the alkaline earth metal cation.     

Sonochemical Synthesis and Photocatalytic Properties of Metal Hydroxide and Carbonate (M:Mg, Ca, Sr or Ba) Nanoparticles

In this work Mg(OH)₂, Ca(OH)₂, CaCO₃, SrCO₃ and BaCO₃ nanoparticles were synthesized via a simple sonochemical reaction at room temperature. Nanoparticles were synthesized via a surfactant-free reaction solvent water. Nanostructures materials were characterized by scanning electron microscopy, X-ray diffraction and fourier transform infrared spectroscopy. The photocatalytic behavior of nanoparticles was evaluated using the degradation of a methyl orange aqueous solution under ultraviolet light irradiation. The results show that metal hydroxide and metal carbonate nanoparticles are promising materials with excellent performance in photocatalytic applications.     

Mass distribution of cluster ions produced from laser ablation of metal-composite-oxides Y-M-Cu-O (M=Ba,Sr, Ca,Mg)

Laser ablation of YMCuO metal-composite-oxides (M=Ba, Sr, Ca, Mg) in high vacuum produced cluster ions with various sizes and compositions. Mass spectra of the cluster ions were recorded by a home-built time-of-flight (TOF) mass spectrometer and the mass distributions were analyzed by a statistical model. For YBa₂Cu₃O_7?x (YBCO) high-Tc superconducting samples, six series of cluster ions were observed. Replacement of barium in the metal-composite-oxide sample with other alkaline earth metal, such as strontium, calcium, or magnesium, not only removed the superconductivity, but also changed the compositions and distributions of the laser generated cluster ions. For instance, copper was only found in the compositions of cluster ions generated from YBCO sample. From comparison of the experimental results, interactions among components of the metal-composite-oxides and the function of alkaline earth metal in superconducting material were discussed.     

A kinetic stability study of MN (MBe,Mg, Ca,Sr, and Ba)

This work describes a structure and kinetic stability study of some complexes with the general formula MN, where M are the alkaline earth metal atoms, Be, Mg, Ca, Sr, and Ba. A complex (A) with two points of attachment to the N₅ ring is the most energetically favored for all metals considered here. Except for Be, structure (B) containing a mono‐coordinated metal atom is a transition state corresponding to the metal atom transfer around the N₅ ring. Pyramidal structure (C) is kinetically unstable with the low isomerization barrier height, ranging from 0.9 to 6.7 kcal/mol. The dissociation barrier heights for the lowest energy isomers (A) are predicted to be 1.2–18.7 kcal/mol (Be to Ba), indicating that kinetic stability increases from lighter to heavier metal atoms. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004     

Über Neue Hexafluororhodate(IV): AIIRhIVF6 (AII = Ba,Sr, Ca,Mg, Zn,Cd, Hg,Ni sowie Cu)

On Novel Hexafluoro Rhodates(IV): A^IIRh^IVF₆. (A^II = Ba, Sr, Ca, Mg, Zn, Cd, Hg, Ni, Cu) We obtained hithertoo unknown BaRhF₆ and SrRhF₆ (both lemon yellow) of (hexag.) BaSiF₆?Type [a = 7.37₉, c = 7.21₁Å bzw. a = 7.15₇, c = 6.94₈ Å] as well as CaRhF₆ (light yellow) [a = 5.26₇, c = 14.61₂ Å], MgRhF₆ (light yellow) [a = 5.02₇, c 13.51₁Å], ZnRhF₅ (light yellow) [a = 4.99₆, c = 13.68₃ Å], CdRhF₆ (light yellow) [a = 5.,12₈ c = 14.44₇ Å], HgRhF₆ (orange) [a = 5.13₃, c = 14.67₆ Å], NiRhF₆ (light brown) [a = 4.96₀, c = 13.51₄ Å] all of (hexag.) LiSbF₆?type. The strukture of CuRhF₆ (light brown) is yet unknown.