Photoelasticity of a MgO single crystal from polarized Brillouin scattering spectroscopy.

MgO is a crystalline solid with significant practical and theoretical value in many fields. Brillouin scattering has long been regarded as a reliable method for accurately measuring the elasticity and photoelasticity of crystals; however, its practical application in photoelasticity has been stagnant. In this paper, three independent photoelastic constants of MgO have been measured for the first time by polarized Brillouin scattering spectroscopy and we have defined a scattering factor containing three photoelastic constants to connect with the Brillouin peak intensity.

Threefold coordinated germanium in a GeO melt.

The local structure around germanium is a fundamental issue in material science and geochemistry. In the prevailing viewpoint, germanium in GeO melt is coordinated by at least four oxygen atoms. However, the viewpoint has been debated for decades due to several unexplained bands present in the GeO melt Raman spectra.

Quantitative Studies on Local Structure of Molten Binary Potassium Germanates.

high temperature Raman spectra of KO-(100-)GeO, samples containing 0, 5, 11.11, 20, 25, 33.3, 40, and 50 %mol KO, were measured.

Temperature-Dependent Raman Spectroscopic Study of the Double Molybdate KBi(MoO).

In situ high-temperature Raman spectra of polycrystalline KBi(MoO) were recorded from room temperature to 1073 K. Thermal stability of the monoclinic KBi(MoO) was examined by temperature-dependent XRD. The monoclinic phase transformed into the scheelite tetragonal structure at 833 K, and then to the monoclinic phase at 773 K.

Mechanism of the Microstructural Evolution of 18Cr2Ni4WA Steel during Vacuum Low-Pressure Carburizing Heat Treatment and Its Effect on Case Hardness.

In this study, vacuum low-pressure carburizing heat treatments were carried out on 18Cr2Ni4WA case-carburized alloy steel. The evolution and phase transformation mechanism of the microstructure of the carburized layer during low-temperature tempering and its effect on the surface hardness were studied. The results showed that the carburized layer of the 18Cr2Ni4WA steel was composed of a large quantity of martensite and retained austenite.

Adsorptive removal of trace thallium(I) from wastewater: A review and new perspectives.

Thallium is an emerging pollutant reported in wastewater along with the increasing mining and smelting of thallium-containing ores in recent years. The complete removal of Tl(I) from wastewater is of significant emergency due to its high toxicity and mobility, however, Tl(I) removal is always confronted with numerous technical difficulties because of the extremely low Tl(I) concentration in wastewater and the disturbances of many accompanying impurity ions. Adsorption is currently the most widely used method for Tl(I) removal on industrial scale and varied kinds of adsorbents such as Prussian blue analogues, biosorbents, and metal oxides have been developed.

Alkali carbonates promote CO capture by sodium orthosilicate.

Sodium orthosilicate was synthesized by a wet chemical method with further calcination at 600 °C. Mixtures of NaSiO and alkali (Li/Na/K) carbonates were prepared by a mechanical mixing method. The CO capture performance of the samples was characterized by dynamic thermogravimetric analyses and in situ XRD and Raman spectroscopy in 80 vol% CO mixed with 20 vol% N.

In Situ Raman Spectroscopy and DFT Studies of the LiGeO Melt Structure.

Knowledge of the molecular-level structure of the LiGeO melt is essential to understand its basic physicochemical properties. In this work, in situ Raman spectroscopy, factor group analysis, and density functional theory (DFT) calculations were applied to investigate the LiGeO crystal Raman spectrum and its transformation during the crystal melting process. Finally, the LiGeO melt structure was determined.

Temperature Dependent Micro-Structure of KAlF₄ from Solid to Molten States.

In situ high temperature X-ray diffraction and Raman spectroscopy were used to investigate the temperature dependent micro-structure of KAlF₄. Density functional theory was applied to simulate the structure of crystalline KAlF₄ while a quantum chemistry ab initio simulation was performed to explore the structure of molten KAlF₄. Two crystal polymorphs demonstrated to be present in solid KAlF₄.

Quantitative Studies on the Structure of Molten Binary Potassium Molybdates by in Situ Raman Spectroscopy and Quantum Chemistry ab Initio Calculations.

The quantitative distribution of different species ( Q and H ) in binary potassium molybdate melts has been investigated by in situ high temperature Raman spectroscopy in conjunction with quantum chemistry (QC) ab initio calculations. The symmetric stretching vibrational wavenumbers of molybdenum nonbridging oxygen bonds in high wavenumber range and their respectively corresponding Raman scattering cross sections were determined and analyzed. Deconvolution of the stretching bands of molybdenum nonbridging oxygen bonds of molten Raman spectra by using the Voigt function was carried out.

Raman and Density Functional Theory Studies of LiMoO Structures in Crystalline and Molten States.

The LiMoO melt structure and its Raman spectral characteristics are the key for establishing the composition-structure relationship of lithium molybdate melts. In this work, Raman spectroscopy, factor group analysis, and density functional theory (DFT) were applied to investigate the structural and spectral details of the H-LiMoO crystal and a LiMoO melt. Factor group analysis shows that the crystal has 171 vibrational modes (84A + 87A), including three acoustic modes (3A), six librational modes (2A + 4A), 21 translational modes (7A + 14A), and 141 internal modes (75A + 66A).

Impacts of Modification of Alloying Method on Inclusion Evolution in RH Refining of Silicon Steel.

This study explores the effect of introducing additional alloy elements not only in a different order but also at different stages of the Ruhrstahl-Heraeus (RH) process of low-carbon silicon steel production. A more economical method, described as "pre-alloying", has been introduced. The evolution of MnO-FeO inclusions produced by pre-alloying was investigated.

In-Situ Studies of Structure Transformation and Al Coordination of KAl(MoO₄)₂ during Heating by High Temperature Raman and Al NMR Spectroscopies.

Recent interest in optimizing composition and synthesis conditions of functional crystals, and the further exploration of new possible candidates for tunable solid-state lasers, has led to significant research on compounds in this family MM(MO₄)₂ (M = alkali metal, M = Al, In, Sc, Fe, Bi, lanthanide; M = Mo, W). The vibrational modes, structure transformation, and Al coordination of crystalline, glassy, and molten states of KAl(MoO₄)₂ have been investigated by in-situ high temperature Raman scattering and Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, together with first principles density functional simulation of room temperature Raman spectrum. The results showed that, under the present fast quenching conditions, Al is present predominantly in [AlO₆] octahedra in both KAl(MoO₄)₂ glass and melt, with the tetrahedrally coordinated Al being minor at approximately 2.

In-situ studies on the micro-structure evolution of AWO (A=Li, Na, K) during melting by high temperature Raman spectroscopy and density functional theory.

In-situ high temperature Raman spectroscopic (HTRS) technique in combination with density functional theory (DFT) analysis has been adopted to investigate the micro-structure of solid and molten AWO (A=Li, Na, K). The [WO] octahedra were found to be connected to each other by corner and edge sharing in the crystalline LiWO and KWO compounds. In the crystal lattice of NaWO, on the other hand, the [WO] tetrahedra and [WO] octahedra were found to coexist and paired by corner sharing.

Investigation on the Structure of a LiBO-LiMoO High-Temperature Solution for Understanding the LiMoO Flux Behavior.

LiBO is the most widely used nonlinear optical crystal. LiMoO (a nominal composition) is a typical flux used to produce large-sized and high-quality LiBO crystals. The structure of the LiBO-LiMoO high-temperature solution is essential to understanding the flux behavior of LiMoO but still remains unclear.

Raman Spectral and Density Functional Theory Analyses of the CsB3O5 Melt Structure.

Melt structures are essential to understand a variety of crystal growth phenomena of alkali-metal triborates, but have not been fully explored. In this work, Raman spectroscopy, coupled with the density functional theory (DFT) method, has been used to solve the CsB3O5 (CBO) melt structure. When the CBO crystal melts, the extra-ring B4-Ø bonds (the B-Ø bonds of BØ4 groups, Ø = bridging oxygen atom) that connect two B3O3Ø4 rings (the basic boron-oxygen unit in the CBO crystal structure) break.

[Study on microstructure of jadeite melt and its glass].

Comprehensive experimental as well as theoretical methods were applied to investigate the structure evolution of jadeite in the hot-melt process, especially on the variation of aluminium coordination number. In-situ high temperature Raman spectroscopic technique was used to record the characteristic Raman spectra of jadeite and its melt with the increasing temperature, consequently, density function theory and ab initio calculation methods were applied to analyze the related micro-structures and aluminium coordination number and simulate the Raman spectra. Results showed that aluminum in jadeite crystal is all six-fold and would transform into four-fold coordination at 1 293K while jadeite being melting.

[Microstructure study on bismuth triborate crystal and its melt at high temperature by Raman spectroscopy].

Temperature dependent Raman spectra of BiB3 O6 crystal and its melt were recorded and the microstructure of BiB3 O6 melt was predicted. Multiple theoretical methods including quantum chemistry ab initio calculation and DFT (Density Function Theory) methods were applied to simulate the BiB3 O6 crystal and melt structure and Raman spectra. It was demonstrated that B-O triangles and Bi lattice in the crystal reveal little affected in structure while B-O tetrahedra shows severe distortion with increasing temperature, especially B-O tetrahedra disappears after being completely melt.

[Raman spectroscopic quantitative analysis of cluster structure of binary alkali silicate glasses].

A calibration method for Raman spectroscopic quantitative analysis of binary alkaline silicate glasses is proposed. By applying ab initio quantum chemistry simulation, Raman optical activities (ROA) of various cluster units consisting of silicon-oxygen tetrahedra (SiOT) with different number of non-bridging oxygen (NBO) can be obtained. Thus, experimental results could be calibrated in order to reflect and represent directly the true relative density of various silicon-oxygen tetrahedra existing inside the silicate glasses.

[Temperature dependent Raman spectra and micro-structure study of cuspidine in solid and liquid phases].

Cuspidine plays an important role in conventional metallurgical continuous casting mould flux. An UV laser source was used to record its ambient and high temperature Raman spectra (temperature range: 298-1 723 K) combined with a charge coupled device (CCD) detector. Both increasing and decreasing processes as well as characteristic spectra and shifts in wavenumber were observed.

[Quantum chemistry ab initio calculation study on microstructure and raman spectra of phosphosilicates].

Quantum chemistry ab initio calculation was applied to study the hyperfine structure of ternary alkali phosphosilicates. Restricted Hartree-Fock method (RHF) with the basis sets of 6-31G(d) was employed to optimize geometric structure and calculate Raman spectra of a series of phosphosilicates model cluster structural units. Stress index of tetrahedron (SIT) was introduced to describe and classify the microstructure of ternary alkali phosphosilicates in order to investigate the effect of phosphorus-oxygen tetrahedron on the micro-environment of silicon-oxygen tetrahedron.

[High temperature Raman spectra and structure study of stolzite-structured PbWO4 crystals and its melt].

Raman spectra of stolzite-structured PbWO4 crystal were recorded from 298 to 1 473 K. All the appearing vibrational modes were interpreted and assigned. The most intense mode at 902.

[A study of phonon vibration like modes for aggregation structure in silicate melts by high temperature Raman spectrum].

Silicate melts are special fractal dimension system that is metastable state of near-way order and far-way disorder. In this paper, the size of nanometer aggregation structure and the frequences of phonon vibration like mode in the low dimension silicate series (CaO-Al2O3-SiO2 and Na2-Al2O3-SiO2 series) synthesized via high temperature melting and sol gel methods were measured by means of small-angle X-ray scattering (SAXS), low wavenumber Raman spectrum (LWRS) and high temperature Raman spectrum (HTRS in situ measuring). The nanometer self-similarity aggregation structure(it's size is about a few nm to a few tens nm) and phonic phonon vibration like modes of low temperature silicate gel, high temperature silicate melts and it's quenching glasses phases were obtained.

[Hyperfine structure study of binary sodium phosphates by Raman spectroscopy].

Quantum chemistry ab initio calculation was applied to study the hyperfine structure of binary sodium phosphates. A series of phosphate model clusters were designed to simulate the microstructure of phosphates with different components. Closed-shell Hatree-Fock method (RHF) and the basis sets of 6-31G (d, p) were employed to optimize structures and calculate Raman frequencies of these phosphate model clusters.