Preparation of nanocrystalline BiFeO<Subscript>3</Subscript> via a simple and novel method and its kinetics of crystallization

The precursor of nanocrystalline BiFeO₃ was obtained by solid-state reaction at low heat using Bi(NO₃)₃·5H₂O, FeSO₄·7H₂O, and Na₂CO₃·10H₂O as raw materials. The nanocrystalline BiFeO₃ was obtained by calcining the precursor. The precursor and its calcined products were characterized by differential scanning calorimetry (DSC), Fourier transform-infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). The data showed that highly crystallization BiFeO₃ with rhombohedral structure (space group R3c (161)) was obtained when the precursor was calcined at 873 K for 2 h. The thermal process of the precursor experienced three steps, which involve the dehydration of adsorption water, hydroxide, and decomposition of carbonates at first, and then crystallization of BiFeO₃, and at last decomposition of BiFeO₃ and formation of orthorhombic Bi₂Fe₄O₉. The mechanism and kinetics of the crystallization process of BiFeO₃ were studied using DSC and XRD techniques, the results show that activation energy of the crystallization process of BiFeO₃ is 126.49 kJ mol⁻¹, and the mechanism of crystallization process of BiFeO₃ is the random nucleation and growth of nuclei reaction.     

Vibrational spectroscopic study of the antimonate mineral bindheimite Pb2Sb2O6(O,OH)

Raman spectroscopy complimented with infrared spectroscopy has been used to characterise the antimonate mineral bindheimite Pb₂Sb₂O₆(O,OH). The mineral is characterised by an intense Raman band at 656 cm⁻¹ assigned to SbO stretching vibrations. Other lower intensity bands at 664, 749 and 814 cm⁻¹ are also assigned to stretching vibrations. This observation suggests the non-equivalence of SbO units in the structure. Low intensity Raman bands at 293, 312 and 328 cm⁻¹ are assigned to the OSbO bending vibrations. Infrared bands at 979, 1008, 1037 and 1058 cm⁻¹ may be assigned to δOH deformation modes of SbOH units. Infrared bands at 1603 and 1640 cm⁻¹ are assigned to water bending vibrations, suggesting that water is involved in the bindheimite structure. Broad infrared bands centred upon 3250 cm⁻¹ supports this concept. Thus the true formula of bindheimite is questioned and probably should be written as Pb₂Sb₂O₆(O,OH,H₂O).     

Synthesis and structural characterization of sol–gel derived titania/poly (vinyl pyrrolidone) nanocomposites

Non hydrolytic sol–gel method was employed to synthesize pure anatase TiO₂ nanocrystals using tetra isopropyl orthotitanate and poly vinylpyrrolidone as precursors. The structural analyses of the prepared samples were carried out using Fourier transform infrared spectroscopy (FT-IR), thermo gravimetric and differential thermal analysis (TG–DTA), X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). The capping of PVP around TiO₂ nanoparticles was confirmed by FT-IR spectroscopy, the interaction being via bridging oxygens of the carbonyl (C=O) and the nanoparticle surface. The XRD, Raman and TEM results indicate that the prepared samples had a pure anatase nano-TiO₂ structure. The particle size analysed by TEM ranged between 7 and 12 nm. The size of the nanocrystals evaluated from the XRD spectra and TEM micrograph is well in agreement. The spacing for the crystal planes was also determined using the ImageJ program applied to the TEM micrographs.     

Synthesis and properties of LiMIIPO4 (MII = Mg,Mn0.5Mg0.5, Co0.5Mg0.5) affected by isodivalent doping and Li-sources

NH₄M^IIPO₄·H₂O (M^II = Mg, Mn_0.5Mg_0.5, Co_0.5Mg_0.5) were synthesized by direct-precipitating method. The olivine-like LiM^IIPO₄ were successfully generated through the solid state reaction between the synthesized NH₄M^IIPO₄·H₂O precursors and two different Li-sources (Li₂CO₃ or LiOH·H₂O). The NH₄M^IIPO₄·H₂O and LiM^IIPO₄ compounds were confirmed by TG/DTG/DTA, AAS/AES, FTIR and XRD methods. The structural and morphological properties of LiM^IIPO₄ compounds were studied by XRD and SEM, respectively. The XRD reflection shifts of olivine-like LiM^IIPO₄ from the Li-source of Li₂CO₃ revealed changing toward higher diffraction angles than that of LiM^IIPO₄ from the Li-source of LiOH·H₂O. The XRD shifts of LiM_0.5Mg_0.5PO₄ (M = Mn or Co) compounds confirmed the formation of the single phase of isodivalent doping of Mn²⁺ and Co²⁺ ions according to the change in the lattice parameters and cell volumes. The morphological investigations of the LiM^IIPO₄ obtained from Li₂CO₃ system illustrated the grain-like shape particles having smaller size of about 150–400 nm on account of the sequential transformations of types: deammoniation, dehydration, polycondensation and decarbonization. Conversely, the larger size particles (300–700 nm) of the LiM^IIPO₄ obtained from LiOH·H₂O were observed due to the shorter transformation path through the reactions of types: deammoniation and dehydration without polycondensation and decarbonization.     

Preparation, molecular structure, and thermal analyses of a novel coordination compound [Cd(AZT)4(H2O)2](PA)2 · 4H2O (AZT = 3-azido-1,2,4-triazole, PA = picrate)

Abstract  The crystal structure of 3-azido-1,2,4-triazole (AZT) has been determined. A novel coordination compound [Cd(AZT)₄(H₂O)₂](PA)₂ · 4H₂O has been synthesized by using 3-azido-1,2,4-triazole as ligand, and its structure has been characterized by using X-ray single crystal diffraction, elemental analysis, and FT-IR spectroscopy. Each cadmium (II) center is coordinated with four N atoms of four AZT molecules and two O atoms of two H₂O molecules to form a slightly distorted octahedron. The optimized molecular structure and NBO charges of 3-azido-1,2,4-triazole have been obtained from the density functional theory (DFT) with the B3LYP method employing the 6-311 + G** basis sets. Thermal decomposition mechanism of [Cd(AZT)₄(H₂O)₂](PA)₂ · 4H₂O has been predicted based on DSC, TG-DTG, and FT-IR analyses. The kinetic parameters of the first exothermic process of [Cd(AZT)₄(H₂O)₂](PA)₂ · 4H₂O were studied by applying the Kissinger’s and Ozawa-Doyle’s methods. Index Abstract  A novel coordination compound [Cd(AZT)₄(H₂O)₂](PA)₂ · 4H₂O has been synthesized by using 3-azido-1,2,4-triazole as ligand and its structure has been characterized by using X-ray single crystal diffraction, elemental analysis, and FT-IR spectroscopy. Each cadmium (II) center is coordinated to form a slightly distorted octahedron. Thermal decomposition mechanism of [Cd(AZT)₄(H₂O)₂](PA)₂ · 4H₂O has been predicted based on DSC, TG-DTG, and FT-IR analyses.      

Vibrational spectroscopic characterization of the phosphate mineral series eosphorite–childrenite–(Mn,Fe)Al(PO4)(OH)2·(H2O)

The phosphate mineral series eosphorite–childrenite–(Mn,Fe)Al(PO₄)(OH)₂·(H₂O) has been studied using a combination of electron probe analysis and vibrational spectroscopy. Eosphorite is the manganese rich mineral with lower iron content in comparison with the childrenite which has higher iron and lower manganese content. The determined formulae of the two studied minerals are: (Mn_0.72,Fe_0.13,Ca_0.01)(Al)_1.04(PO₄, OHPO₃)_1.07(OH_1.89,F_0.02)·0.94(H₂O) for SAA-090 and (Fe_0.49,Mn_0.35,Mg_0.06,Ca_0.04)(Al)_1.03(PO₄, OHPO₃)_1.05(OH)_1.90·0.95(H₂O) for SAA-072. Raman spectroscopy enabled the observation of bands at 970 cm⁻¹ and 1011 cm⁻¹ assigned to monohydrogen phosphate, phosphate and dihydrogen phosphate units. Differences are observed in the area of the peaks between the two eosphorite minerals. Raman bands at 562 cm⁻¹, 595 cm⁻¹, and 608 cm⁻¹ are assigned to the ν₄ bending modes of the PO₄, HPO₄ and H₂PO₄ units; Raman bands at 405 cm⁻¹, 427 cm⁻¹ and 466 cm⁻¹ are attributed to the ν₂ modes of these units. Raman bands of the hydroxyl and water stretching modes are observed. Vibrational spectroscopy enabled details of the molecular structure of the eosphorite mineral series to be determined.     

Synthesis and crystal structure of a new copper (II) complex,designed to produce efficient successor of Cu2O,toward synergy of adsorption and photodegradation of MB

A new copper (II) coordination complex formulated as [Cu (dipic)(phen)(2-MePy)]. 2H₂O ( 1 ) where phen = 1, 10-phenanthroline, dipic²⁻ = pyridine-2,6-dicarboxylato and 2-MePy = 2-methyl pyrrole was synthesized through a simple and environment-friendly reaction under ultrasound irradiation. Also, complex 1 was synthesized by hydrothermal process at 120 °C for 3 days. The corresponding structure of complex 1 was characterized by elemental analysis, atomic absorption spectroscopy (AAS), inductively coupled plasma (ICP), conductivity measurement, Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, ultraviolet–visible spectroscopy (UV–Vis), thermal gravimetric analysis (TGA), differential thermal analysis (DTA), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and fluorescence. The crystal structure of the hydrothermally synthesized complex was characterized by single crystal X-ray diffraction (SC-XRD(, which revealed a triclinic structure. In the remainder of this study, the Cu₂O nanoparticles have been prepared via thermal decomposition of hydrothermal and ultrasound complexes and characterized by ICP, FT-IR, powder X-ray diffraction (XRD), SEM and N₂ adsorption/desorption. Adsorption and visible-light-driven photocatalytic capabilities of two synthetic Cu₂O were investigated in the removal of MB from water. The result showed that the synthesized catalysts have good catalytic activity and the photocatalytic degradation is more effective in dye removal of MB compared with the adsorption.     

Hydrothermal conversion of zeolite omega from magadiite with assistance of seed crystals

In this work, we report a rapid and sustainable synthetic strategy of zeolite omega with the addition of omega seeds via the transformation of magadiite with an initial chemical recipe of 0.76 NaOH: SiO₂: 0.01 Al₂O₃: 7–14H₂O, and the crystallization time was shortened to 5 h at 80 °C. The effect of experiment parameters has been discussed in details. In addition, the conversion behavior and the changes of secondary building units were characterized and studied by X-ray diffraction (XRD), scanning electron microscopy, Fourier Transform infrared (FT-IR), and Raman spectroscopy and ²⁷Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy. During the conversion process, omega seeds would be partially destroyed and residual seeds supplied substrate for the growth of zeolite omega, most parts of five-membered rings and six-membered rings in magadiite were remained as building units to promote the formation of zeolite omega, and Al species preferred to enter T2 position which was located in six-membered rings. The toluene adsorption property of final product was also measured.     

Structure and optical properties of [Ba1–xY2x/3](Zr0.25Ti0.75)O3 powders

[Ba_1–xY_2x/3](Zr_0.25Ti_0.75)O₃ powders with different yttrium concentrations (x = 0, 0.025 and 0.05) were prepared by solid state reaction. These powders were analyzed by X-ray diffraction (XRD), Fourier transform Raman scattering (FT-RS), Fourier transform infrared (FT-IR) and X-ray absorption near-edge (XANES) spectroscopies. The optical properties were investigated by means of ultraviolet–visible (UV–vis) absorption spectroscopy and photoluminescence (PL) measurements. Even with the addition of yttrium, the XRD patterns revealed that all powders crystallize in a perovskite-type cubic structure. FT-RS and FT-IR spectra indicated that the presence of [YO₆] clusters is able to change the interaction forces between the O–Ti–O and O–Zr–O bonds. XANES spectra were used to obtain information on the off-center Ti displacements or distortion effects on the [TiO₆] clusters. The different optical band gap values estimated from UV–vis spectra suggested the existence of intermediary energy levels (shallow or deep holes) within the band gap. The PL measurements carried out with a 350 nm wavelength at room temperature showed that all powders present typical broad band emissions in the blue region.     

Infrared, optical absorption, and EPR spectroscopic studies on natural gypsum

The natural gypsum has been investigated by infrared, Raman, X-ray diffraction, optical absorption and electron paramagnetic resonance spectroscopy. The fundamental stretching and bending vibrations observed in the infrared region for SO₄²⁻ and H₂O are compared with the near-infrared overtones and combinations of these vibrations. MIR and Raman spectral features are attributed to sulfate fundamentals and lattice vibrations of H₂O, SO₄²⁻. The charge transfer and ligand field transition bands were observed near 490, 630, and 800–900 nm and were compared to those of iron oxides. The optical absorption spectrum indicates the presence of ferric and ferrous ions in the mineral. The site symmetry of Fe(III) in the sample is tetragonally distorted. EPR results indicate the presence of the ferric ion in a tetragonally distorted state.     

制备条件对Cu2O结构及甲醛乙炔化性能的影响

以Cu（NO₃）₂·3H₂O为铜源,在液相还原过程中,调变沉淀剂NaOH、还原剂L-抗坏血酸钠的加入顺序制备了Cu₂O,借助X射线粉末衍射（XRD）、傅里叶变换红外光谱（FT-IR）、拉曼光谱（Raman）、俄歇电子能谱（XAES）和H₂程序升温还原（H₂-TPR）等手段研究了制备条件对Cu₂O结构及催化甲醛乙炔化性能的影响.结果表明,调变NaOH及L-抗坏血酸钠的添加方式改变了Cu₂O的结晶度与粒径尺寸,从而使Cu₂O表现出不同的炔化性能.先加入NaOH,后加入抗坏血酸钠,Cu₂O结晶度高,粒径大,难以转化为活性物种炔化亚铜;先加入抗坏血酸钠,后加入NaOH,Cu₂O被过度还原为非活性的金属Cu,两者均造成催化剂活性较低.而NaOH和抗坏血酸钠混合后添加的方式制备出表面Cu₂O结晶完整而体相Cu₂O分散度高的样品,这使得Cu₂O高效转化为炔化亚铜活性物种,表现出最优的炔化性能,在适宜的反应条件下,1,4-丁炔二醇收率达到71.7%,经6次循环后,仍保持在56.5%.     

Synthesis and characterization of sol–gel derived bioactive CaO–SiO<Subscript>2</Subscript>–P<Subscript>2</Subscript>O<Subscript>5</Subscript> glasses containing magnetic nanoparticles

Magnetic bioglasses in the system CaO–SiO₂–P₂O₅ were prepared by interaction of acetic acid vapors with iron nitrate dispersed on the surface of sol–gel derived porous silicate network. Upon pyrolysis, the created iron acetate species transform into magnetic iron oxide nanoparticles. X-ray diffraction (XRD), FT-infrared (FT-IR) spectroscopy and surface area measurements (BET) were employed to monitor the evolution of glass structural features during the synthetic pathway as well as the structure and the texture of the resultant glasses. XRD, Raman spectroscopy and vibration magnetic measurements (VSM) revealed the features of magnetic phases, developed in the form of γ-Fe₂O₃ and magnetite. The obtained glasses exhibit in vitro bioactivity, expressed by spontaneous formation of hydroxyapatite on their surface after immersion in SBF at 37 °C, confirmed with μ-Raman and FT-IR spectroscopies.     

Synthesis,crystal structure and magnetic properties of a new tri‐nuclear iron (II,III) complex,a precursor for the preparation of superparamagnetic Fe3O4 nanoparticles applicable in the removal of Cd2+

This study reports the structural and spectroscopic characterization of a novel metal organic compound formulated as [Fe (bpy)₃] [Fe (dipic)₂]₂.7H₂O ( 1 ) (dipic = pyridine‐2,6‐dicarboxylate and bpy = 2,2^′‐bipyridine). 1 was investigated by elemental analysis, FT‐IR spectroscopy, powder X‐ray diffraction and single crystal X‐ray diffraction (SC‐XRD), which revealed a triclinic structure of expected composition. Thermal degradation of 1 was also investigated. Complex 1 was used as a precursor to prepare superparamagnetic nanoparticles of Fe₃O₄ by thermal analysis. The obtained Fe₃O₄ was characterized by Fourier transformed infrared spectroscopy (FT‐IR), powder X‐ray diffraction (XRD) and scanning electron microscopy (SEM). Fe₃O₄ nanoparticles were used as a nano‐adsorbent to remove Cd²⁺ from water at room temperature. The results showed that this nano‐adsorbent is effective in removing Cd²⁺ from contaminated water sources, and that the maximal effectivity of adsorption occurs at pH = 6. Magnetic measurements of complex 1 and Fe₃O₄ nanoparticles at room temperature revealed paramagnetic and superparamagnetic behavior, respectively.     

Non-isothermal decomposition kinetics of synthetic serrabrancaite (MnPO<Subscript>4</Subscript> · H<Subscript>2</Subscript>O) precursor in N<Subscript>2</Subscript> atmosphere

The thermal decomposition of synthetic serrabrancaite (MnPO₄ · H₂O) was studied in N₂ atmosphere using TG-DTG-DTA. Thermal analysis results indicate that the decomposition occurs in two stages, which are assigned to the dehydration and the reduction processes and the final product is Mn₂P₂O₇. X-ray powder diffraction, FT-IR and FT-Raman techniques were used for identification of the solid decomposition product. The decomposition kinetics analysis of MnPO₄ · H₂O was performed under non-isothermal condition through isoconversional methods of Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS). The dependences of activation energies on the extent of conversions are observed in the dehydration and the reduction reactions, which could be concluded the “multi-step” processes.     

Vibrational spectroscopic study of the arsenate mineral strashimirite Cu8(AsO4)4(OH)4·5H2O—Relationship to other basic copper arsenates

The basic copper arsenate mineral strashimirite Cu₈(AsO₄)₄(OH)₄·5H₂O from two different localities has been studied by Raman spectroscopy and complemented by infrared spectroscopy. Two strashimirite mineral samples were obtained from the Czech (sample A) and Slovak (sample B) Republics. Two Raman bands for sample A are identified at 839 and 856 cm⁻¹ and for sample B at 843 and 891 cm⁻¹ are assigned to the ν₁ (AsO₄³⁻) symmetric and the ν₃ (AsO₄³⁻) antisymmetric stretching modes, respectively. The broad band for sample A centred upon 500 cm⁻¹, resolved into component bands at 467, 497, 526 and 554 cm⁻¹ and for sample B at 507 and 560 cm⁻¹ include bands which are attributable to the ν₄ (AsO₄³⁻) bending mode. In the Raman spectra, two bands (sample A) at 337 and 393 cm⁻¹ and at 343 and 374 cm⁻¹ for sample B are attributed to the ν₂ (AsO₄³⁻) bending mode. The Raman spectrum of strashimirite sample A shows three resolved bands at 3450, 3488 and 3585 cm⁻¹. The first two bands are attributed to water stretching vibrations whereas the band at 3585 cm⁻¹ to OH stretching vibrations of the hydroxyl units. Two bands (3497 and 3444 cm⁻¹) are observed in the Raman spectrum of B. A comparison is made of the Raman spectrum of strashimirite with the Raman spectra of other selected basic copper arsenates including olivenite, cornwallite, cornubite and clinoclase.     

Syntheses, spectral and thermal analyses of heteronuclear aqua(2-methylpyrazine)metal(II) complexes with tetracyanonickelate ion and crystal structure of supramolecular [Cd(H2O)(2mpz)Ni(μ-CN)4]n complex

Polymeric tetracyanonickelate complexes of the type [M(H₂O)(2mpz)Ni(μ-CN)₄] _n (2mpz = 2-methylpyrazine, M = Mn(II) (1) or Cd(II) (2)) have been prepared and characterized by FT-IR, Raman spectroscopy, thermal, and elemental analyses. The crystal structure of supramolecular [Cd(H₂O)(2mpz)Ni(CN)₄] _n complex has been determined by X-ray single crystal diffraction. It crystallizes in the orthorhombic system, space group Pnma. The structure consists of corrugated and cyanide-bridged polymeric two-dimensional networks. In the Hofmann-type complexes, the coordination environment of the M(II) ions can be described as distorted octahedral geometry, whereas around the Ni(II) center has square planar geometry. The spectral features suggest that the 2mpz is coordinated to metal ions of the adjacent layers of [M-Ni(CN)₄] _n as monodentate ligand. The thermal decomposition of these complexes takes place in three stages: (i) dehydration, (ii) decomposition of the 2-methylpyrazine ligands, and (iii) release of the CN groups and burning of organic residue.     

多孔纳米Ce-M-O(M=Pr,La)粉末的微波诱导燃烧合成及其表征

使用Ce(NO₃)₃•6H₂O, Pr(NO₃)₃•6H₂O, La(NO₃)₃•6H₂O, 尿素为原料, 利用微波引诱燃烧法合成了多孔纳米Ce-M-O (M＝Pr, La)固溶体. 使用XRD, X光电子能谱仪(XPS), Raman光谱仪, 红外光谱仪(FT-IR), 透射电镜(TEM), 场发射扫描电镜(FE-SEM)等仪器对纳米粉体进行了表征. XRD分析显示Ce-M-O粉体的粒径在20～50 nm之间, 且所有样品均具有萤石结构. XPS证明在Ce-Pr-O固溶体中Pr以＋3和＋4两种形式存在. Raman光谱表明随着M^3＋的掺杂, 在CeO₂晶格中产生氧缺陷, 且缺陷浓度随掺杂量增加不断提高. 红外光谱证明Ce—O键的吸收峰在1400 cm^－1左右, 且由于M^3＋的掺杂在2346 cm^－1的吸收峰消失. TEM照片说明样品具有类盘状的网络纳米微晶结构. 扫描图像说明产物具有多孔的外貌特征, 且孔径分布在2～40 nm之间.     

Synthesis and characterization of NiO nanoclusters via thermal decomposition

Thermal decomposition process has been developed to synthesize nickel oxide (NiO) nanoclusters via the reaction between a new precursor, nickel oxalate [Ni(O₄C₂)(H₂O)₄] and oleylamine (C₁₈H₃₇N). The combination of triphenylphosphine (C₁₈H₁₅P) and C₁₈H₃₇N were added as surfactants to control the particle size. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and ultraviolet–visible (UV–Vis) spectroscopy. The synthesized NiO nanoclusters have a cubic structure with average size 2–10 nm.     

Some thermodynamic functions and kinetics of thermal decomposition of NH<Subscript>4</Subscript>MnPO<Subscript>4</Subscript> · H<Subscript>2</Subscript>O in nitrogen atmosphere

The ammonium manganese phosphate monohydrate (NH₄MnPO₄ · H₂O) was found to decompose in three steps in the sequence of: deammination, dehydration and polycondensation. At the end of each step, the consecutive one started before the previous step was finished. The thermal final product was found to be Mn₂P₂O₇ according to the characterization by X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy. Vibrational frequencies of breaking bonds in three stages were estimated from the isokinetic parameters and found to agree with the observed FTIR spectra. The kinetics of thermal decomposition of this compound under non-isothermal conditions was studied by Kissinger method. The calculated activation energies E_a are 110.77, 180.77 and 201.95 kJ mol⁻¹ for the deammination, dehydration and polycondensation steps, respectively. Thermodynamic parameters for this compound were calculated through the kinetic parameters for the first time.     

Raman spectroscopic study of the antimonate mineral roméite

Raman spectroscopy has been sued to study the antimony containing mineral roméite Ca₂Sb₂O₆(OH,F,O) from three different origins. Roméite is a calcium antimonate mineral of the pyrochlore group. An intense Raman band at ～518 cm^?1 for roméite is assigned to the SbO ν₁ symmetric stretching mode and the band at 466 cm^?1 to the SbO ν₃ antisymmetric stretching mode. The Raman band at 303 cm^?1 is attributed to the OSbO bending mode. Some variation in band positions is observed and is attributed to the variation in composition between the three mineral samples.