Synthesis and efficient blue-emitting of Eu2+-activated borate fluoride BaAlBO3F2

Eu²⁺-doped borate fluoride BaAlBO₃F₂ was synthesized by the conventional high temperature solid state reaction. The crystal phase formations were confirmed by X-ray powder diffraction (XRD) measurements and the structure refinement. The photoluminescence (PL) excitation and emission spectra, and the decay curves were investigated. Eu²⁺-doped BaAlBO₃F₂ phosphor can be efficiently excited by near-UV light and presents narrow blue luminescence band centered at 450 nm. The maximum absolute quantum efficiency (QE) of BaAlBO₃F₂:0.05Eu²⁺ phosphor was measured to be 76% excited at 398 nm light at 300 K. The thermal stability of the blue luminescence was evaluated by the luminescence decays as a function of temperature. The phosphor shows an excellent thermal stability with high thermal activation-energy on temperature quenching effects because of the rigid crystal lattices.     

Synthesis and crystal structure of tetramethylammonium fluoride octadecasil

Octadecasil, a clathrate-type inclusion compound, has been synthesized hydrothermally at 453 K with a gel having the composition 1.0SiO₂:0.53tetramethylammonium (TMA⁺):0.54fluoride:86H₂O. The crystal structure has been determined based on powder X-ray diffraction data taken at 298 K, and has been refined using Rietveld method. The result confirms the AST-type, all-silica framework model developed by Caullet et al. [P. Caullet, J.L. Guth, J. Hazm, J.M. Lamblin, H. Gies, Eur. J. Solid State Inorg. Chem. 28 (1991) 345]. Furthermore, by using a rigid body model the position and orientation of the occluded TMA⁺ cation in the rhombododecahedral [4⁶6¹²] cage can be determined; F⁻ anion has been located in the hexahedral [4⁶] cage. The unit cell parameters, in the tetragonal space group I4/m, have been refined as: a = b = 9.07 Å, c = 13.44 Å, cell volume = 1104.97 Å³. The refined unit cell composition is |[N(CH₃)₄⁺]_2.0F⁻_1.9|[Si₂₀O₄₀], i.e., both TMA⁺ and F⁻ ions possess near full occupancies, and compensate each other's electronic charges. The crystallization of the AST framework structure is the result of a cooperative structure-directing effect of both ions.     

Synthesis,crystal structure and thermal analysis of a new stilbazolium salt crystal

A new organic crystal of 4-N, N-dimethylamino-4′-N′-methyl-stilbazolium benzene sulfonate (DASBS) was synthesized and characterized for the first time. It is a derivative of 4-N, N-dimethylamino-4′-N′-methyl-stilbazolium tosylate (DAST) with the benzene sulfonate replacing p-toluenesulfonate. Single crystal XRD demonstrated that the crystal structure of DASBS·H₂O was triclinic. The thermal analysis of this new crystal was also conducted, and the melting point was obtained to be 232°C.     

Synthesis, crystal structure and magnetic properties of a new lithium cobalt metaphosphate, LiCo(PO3)3

A new lithium cobalt metaphosphate, LiCo(PO₃)₃, is reported for the first time, which was discovered during the exploratory synthesis in Li-Co-P-O system by solid state reaction. The structure has been refined by powder X-ray Rietveld refinement method (P2₁2₁2₁, a = 8.5398(2) Å, b = 8.6326(2) Å and c = 8.3520(2) Å, Z = 4, R_p = 13.6%, R_wp = 19.4%, R_exp = 17.7%, S = 1.11, χ² = 1.23). It is isostructural with LiM(PO₃)₃ (M = Fe, Cu). It contains (PO₃)¹⁻ chains with the Co atoms localized in the octahedral sites, bridging four neighboring chains. The magnetic susceptibility measurement showed a typical paramagnetic behavior of high spin of Co²⁺, following the Curie-Weiss law in the temperature range of 5-300 K. Unlike the olivine type lithium cobalt phosphate, LiCoPO₄, cyclic voltammetry of LiCo(PO₃)₃ assembled in the coin-type cell showed no electrochemical activity in the voltage region of 1-5 V versus Li/Li⁺.     

Optical properties of BaCaBO3F crystal

The optical transmission spectra of BaCaBO₃F (abbr. BCBF) crystal have been measured at room temperature. The refractive indices have been measured with the minimum deviation method and fitted to the Sellmeier equations. The nonlinear optical coefficient d₂₂ of BCBF crystal determined by the Maker fringe technique is 0.74d₃₆(KDP).     

Single crystal growth,structure and properties of TlHgBr3

High-quality inclusion-free single crystals of ternary thallium mercury bromide, TlHgBr₃, were successfully grown by Bridgman–Stockbarger method. For the pristine surface of the TlHgBr₃ single crystal, X-ray photoelectron core-level and valence-band spectra were measured. The comparison on a common energy scale of the X-ray photoelectron valence-band spectrum of TlHgBr₃ and the X-ray emission Br Kβ₂ band, representing peculiarities of the energy distribution of the Br 4p states revealed that the main contribution of the valence Br p states, occurred in the upper portion of the valence band, with also their significant contributions in other valence band regions. It has been determined that TlHgBr₃ is a semiconductor with the bandgap energy value of E_g = 2.51 eV at 100 K. The E_g value decreased up to 2.44 eV when temperature increased to 300 K.     

Synthesis of a new netlike nano zinc borate

A new netlike nano zinc borate ZnO·yB₂O₃·zH₂O (y = 0.3-0.4, z = 1.0-1.4) with amorphous phase was prepared via coordination homogeneous precipitation method in this paper. XRD, FESEM and TG were used to characterize the products. The morphology of the samples was composed of fibers with diameter about 15 nm and length about hundreds of nanometers, some of which entangled each other to form dendritic or interconnected networks. The pilot study revealed that the product had better char formation effect than the commercial ZB2335 when it was introduced into polypropylene (PP) and high-density polyethylene (HDPE) as flame-retardant filler.     

Electronic structure of alkali-metal/alkaline-earth-metal fluorine beryllium borate NaSr3Be3B3O9F4 single crystal: DFT approach

The electronic band structure, total and angular momentum resolved projected density of states for NaSr₃Be₃B₃O₉F₄ are calculated using the all-electron full potential linearized augmented plane wave plus local orbitals (FP-LAPW + lo) method. The calculations are performed within four exchange correlations namely; local density approximation (LDA), general gradient approximation (PBE-GGA), Engel–Vosko generalized gradient approximation (EVGGA) and the recently modified Becke–Johnson potential (mBJ). Calculations suggest that NaSr₃Be₃B₃O₉F₄ is a direct wide band gap semiconductor. The exchange correlations potentials exhibit significant influence on the value of the energy gap being about 4.82 eV (LDA), 5.16 eV (GGA), 6.20 (EVGGA) and 7.20 eV (mBJ). The mBJ approach succeed by large amount in bringing the calculated energy gap closer to the experimental one (7.28 eV). The angular momentum resolved projected density of states shows the existence of a strong hybridization between the various orbitals. In additional we have calculated the electronic charge density distribution in two crystallographic planes namely (1 0 1) and (0 0 −1) to visualized the chemical bonding characters.     

Synthesis,crystal structure and electrochemical properties of the manganese-doped LiNaFe[PO4]F materials

The new compounds LiNaFe_1−xMn_x[PO₄]F (x ≤ 1/4) were synthesized by a solid state reaction route. The crystal structure of LiNaFe_3/4Mn_1/4[PO₄]F was determined from single crystal X-ray diffraction data. LiNaFe_3/4Mn_1/4[PO₄]F crystallizes with the Li₂Ni[PO₄]F-type structure, space group Pnma, a = 10.9719(13), b = 6.3528(7), c = 11.4532(13) Å, V = 798.31(16) Å³, and Z = 8. The structure consists of edge-sharing (Fe_3/4Mn_1/4)O₄F₂ octahedra forming (Fe_3/4Mn_1/4)FO₃ chains running along the b-axis. These chains are interlinked by PO₄ tetrahedra forming a three-dimensional framework with the tunnels and the cavities filled by the well-ordered sodium and lithium atoms, respectively. The manganese-doped phases show poor electrochemical behavior comparing to the iron pure phase LiNaFe[PO₄]F.     

Synthesis of PbZr0.7Ti0.3O3 nanoparticles in a new tetragonal crystal structure with a polymer precursor

Nanoparticles (16- to 25-nm diameter) of PbZr_0.7Ti_0.3O₃, lead zirconate titanate (PZT), are synthesized by a controlled reconstructive thermal decomposition and crystallization from an amorphous polymer precursor with polyvinyl alcohol (PVA) and sucrose at 400 to 700 °C in air. When adding through a mixed acidic solution (with stirring) the ingredients of Pb²⁺ (nitrate) and Zr⁴⁺/Ti⁴⁺ (oxyhydroxides) cations mix-up with PVA-sucrose polymer molecules (dissolved in water) and reorganize in a dispersed structure of precursor. A dispersed structure of the cations through the polymer molecules retain on evaporating (at 50 to 80 °C in air) the excess water in a solid polymer precursor. It is found that a single phase compound of PbZr_0.7Ti_0.3O₃ forms on heating it at 400 to 700 °C temperature in air. It has a new tetragonal crystal structure in comparison to the rhombohedral bulk structure in the Zr-rich or the tetragonal structure in the Ti-rich PZTs. The PbZr_0.7Ti_0.3O₃ nanoparticles calcined under selected conditions in this polymorph are characterized by X-ray diffraction and microstructure in correlation with thermal analysis of the polymer precursor.     

Synthesis, structure, growth and physical properties of a novel organic NLO crystal: 1,3-Dimethylurea dimethylammonium picrate

A novel noncentrosymmetric crystal was prepared from 1,3-dimethylurea dimethylammonium picrate, C₁₁H₁₈N₆O₈ (DMUP), which was designed for second harmonic generation. DMUP crystals exist in noncentro symmetric space group Cmc2₁ with unit cell dimensions a = 14.288(4) Å, b = 17.023(5) Å, c = 6.8268(13) Å, α = β = γ = 90° and volume = 1660.5(8) Å³. The crystal structure of DMUP has been determined using single crystal X-ray diffraction studies. The single crystals of DMUP were successfully grown by the slow evaporation method with dimensions 10 mm × 4 mm × 3 mm using dimethylformamide as solvent. The structural perfection of the grown crystals has been analysed by High-resolution X-ray diffraction (HRXRD) rocking curve measurements. Powder test with Neodymium-doped Yttrium aluminum garnet (Nd:YAG) laser radiation shows a high second harmonic generation (SHG). The laser induced surface damage threshold for the grown crystal was measured using Nd:YAG laser.     

Synthesis and crystal structure of InP3

Higher indium phosphide InP₃ is obtained under high pressure of 3 GPa at 1200°C. The crystal structure was analyzed to be isomorphous with SnP₃, and GeP₃ having lattice parameters of $\text{a}\text{= 7.449}\text{A}\text{?}$ and $\text{c}\text{= 9.885}\text{A}\text{?}$. InP₃ is a metallic conductor although it is less in the amount of valence electrons than its isomorphous MP₃ of Ge and of Sn.     

Synthesis,characterization and electrical properties of a lead sodium vanadate apatite

The lacunary lead sodium vanadate apatite Pb₈Na₂(VO₄)₆ was synthesized by the solid-state reaction method. The compound was characterized by X-ray powder diffraction, infrared (IR) absorption spectroscopy and Raman scattering spectroscopy.By comparing the effect of vanadate and phosphate ions on electrical properties, it was concluded that Pb₈Na₂(VO₄)₆ apatite is better conductor than Pb₈Na₂(PO₄)₆ apatite.     

一种新型防老剂的合成、表征及性能研究

以中间体(N,N,N’,N’-四丙酸甲酯-1,4-苯二胺)、1,2,2,6,6-五甲基哌啶醇为原料,在四异丙基钛酸酯为催化剂的条件下,通过酯交换反应合成了一种未见文献报道的高度对称的树枝状结构的化合物—新型防老剂(N,N,N’N’-[1,4苯二胺]-丙酸[1,2,2,6,6]-五甲基]哌啶醇酯)。产物的结构通过红外(FT-IR)、液相色谱-质谱(LC-MS)、元素分析及核磁(1 HNMR)等确定。为了研究新型防老剂的性能,实验将合成的新型防老剂、防老剂D(N-苯基-β-萘胺)、光稳定剂GW-622分别添加到天然橡胶中制成胶片,对其进行抗热氧老化性能和耐紫外光老化性能测试。结果表明合成的新型防老剂具有良好的抗热氧老化性能和耐紫外光老化性能。     

Synthesis,crystal structure,thermal analysis and dielectric properties of two mixed trichlorocadmiates (II)

K_0.57(NH₄) _0.43CdCl₃ and K_0.25(NH₄) _0.75CdCl₃ are orthorhombic, space group Pnma, Z = 4, with a = 8.8760(4) Å, b = 3.9941(2) Å, c = 14.7004(7) Å, and Z = 4, a = 8.9567(9) Å, b = 3.9957(4) Å, c = 14.855 (2) Å, respectively. Final R values are 0.01 and 0.02 for 608 and 834 reflections, respectively. In both the materials, the crystal structure has been determined by X-ray single crystal analysis at room temperature (293 K). The compound structures consist of K⁺ (or NH\(_{{4}}^{{+}})\) cations and double chains of CdCl₆ octahedra sharing one edge extending along b-axis. The mixture of K⁺/NH\(_{{4}}^{{+}}\) cations are located between the double chains ensuring the stability of the structure by ionic and hydrogen bonding contacts N/K–H …Cl. Spectroscopic, dielectric and differential scanning calorimetry (DSC) measurements were performed to discuss the mechanism of the phase transition. These studies show that these materials, K_0.57(NH₄)_0.43CdCl₃and K_0.25(NH₄)_0.75CdCl₃, undergo a phase transition at 438 and 454 K, respectively.     

Synthesis, crystal and molecular structure, and spectral properties of guanidinium salt of complex uranyl 2-methoxybenzoate

A crystalline uranyl 2-methoxybenzoate, [C(NH₂)₃][UO₂L₃]·H₂O, was synthesized. Its structure was determined by single crystal X-ray diffraction, and the electronic and IR spectra were recorded. The coordination number of the U atom is 8, with methoxyl O atom not involved in coordination bonding with uranyl. The structure contains a system of hydrogen bonds with water molecule of crystallization and guanidinium cation acting as proton donors. The electronic absorption spectrum of the crystalline complex has a pronounced vibronic structure, whereas in the solution spectrum all the lines are strongly broadened. This may be due to dissociation of the complex anion in solution, which leads to superposition of several spectra. In the IR spectrum, there is a set of band characteristic of guanidinium cations. The uranyl group in [C(NH₂)₃][UO₂L₃]·H₂O has almost symmetrical structure. Therefore, only the band of its antisymmetric vibrations is observed in the IR spectrum.