Amorphous anodic oxide films on InAlP have been grown at high efficiency in sodium tungstate electrolyte. The films are shown to comprise an outer layer containing indium species, an intermediate layer containing indium and aluminium species and an inner layer containing indium, aluminium and phosphorus species_. The layering correlates with the influence on cation migration rates of the energies of In³⁺–O, Al³⁺–O and P⁵⁺–O bonds, which increase in this order. The film surface becomes increasingly rough with increase of the anodizing voltage as pores develop in the film, which appear to be associated with generation of oxygen gas.

 

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Due to unknown effects of the potential exposure of the terrestrial environment to tungsten substances, a series of toxicity studies of sodium tungstate (Na₂WO₄) was conducted. The effect on earthworm (Eisenia fetida) survival and reproduction was examined using Organisation for Economic Co-operation and Development (OECD) Guideline 222. No effect on either endpoint was seen at the highest concentration tested, resulting in a 56-d no-observed-effect concentration (NOEC) of ≥586 mg tungsten/kg dry soil (nominal concentrations). The effect of sodium tungstate on emergence and growth of plant species was examined according to OECD Guideline 208: oat (Avena sativa), radish (Raphanus sativus), and lettuce (Lactuca sativa). No effects on emergence, shoot height, and dry shoot weight were observed in oats exposed to the highest concentration, resulting in a 21-d NOEC of ≥586 mg tungsten/kg dry soil. The NOECs for radish and lettuce were 65 and 21.7 mg tungsten/kg dry soil (nominal concentrations), respectively. Respective 21-d median effective concentration values (EC50) for radish and lettuce were >586 and 313 mg tungsten/kg dry soil (based on shoot height) (confidence level [CL] -8.5-615); EC25 values were 152 (CL 0-331) and 55 (CL 0-114) mg tungsten/kg dry soil. Results are consistent with the few other tungsten substance terrestrial toxicity studies in the literature.

 

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Fluorescence, excitation, and pulsed fluorescence measurements have been made on a single crystal of CaWO₄ over a wide temperature range. The temperature dependences of the integrated fluorescence intensities and lifetimes were obtained for different excitation wavelengths. A sharp increase in the fluorescence lifetimes is observed below about 75°K and zero‐phonon lines can be observed. These results are used to formulate a model for the tungstate luminescent center based on the ion in a crystal field of S ₄ symmetry. Energy migration and impurity trapping effects are also discussed.

 

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The influence of annealing in different atmospheres on absorption and luminescent properties of high-quality undoped CaWO₄ single crystals is presented. The decreasing of green emission intensity after annealing in oxygen and air have been revealed, while two well-defined maxima near 25,000 and 32,000cm^-1 can be observed in the induced absorption spectra. These maxima are attributed to the interstitial oxygen, possibly in the form of the O⁻-centre. The increase of the blue/green luminescence ratio has been revealed after annealing in nitrogen while the crystal transparency remains unaffected. The possible ways to reduce slow green emission component without changing crystal absorption are shown. Structure of colour centres and the models of revealed processes are discussed.

 

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The geff=30/7 isotropic signal in the EPR of high-spin Fe3+ compounds is discussed for both tetragonal rhombic crystal fields by reference to the resonance in calcium tungstate. The Fe3+/CaWO4 EPR signals are shown to arise from Fe3+ in two slightly different interstitial sites in the crystal; the crystal field in both sites is predominantly rhombic. Highly anisotropic signals arising from transitions within the other two Kramers' doublets were positively identified leading to an unambiguous calculation of the spin Hamiltonian parameters. The results are likely to be of great value in analysing similar Fe3+ spectra in crystals of biological importance.

 

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Tungsten tetrachloride is a black needle-like crystals, orthorhombic structure, at 300-500 ℃will cause disproportionation reaction to generate tungsten hexachloride and tungsten dichloride. Tungsten tetrachloride at 475 ℃ and vacuum can produce by aluminum or white phosphorus restore to tungsten hexachloride. Tungsten tetrachloride producing processes are as follows:
1.In an inert gas oven, mixed 5g tungsten hexachloride and polytetrafluoroethylene，  put them into bottom No.6 from the manifold No.4 as is shown in the picture. Then fusion seal manifold No.4. Cooled No.6 with dry ice, and open the cock which made by polytetrafluoroethylene exhaust from manifold No.2.
2.Using the vacuum distillation method introduced refined dehydration tetrachlorethylene from the outside to bottom No.6 reach 30mL. After recovery at room temperature, vacuum and dipped No.6 into transparent oil bath with a 500W light bulbs, at 150 ℃ for 3 days.
3.After the reaction is cooled and upside downs the device, precipitated by a glass filter from manifold No.3.
4.In the oven which filled with inert gas, cut off the bottom No.6, remove product on the glass filter.

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Tungsten tetrachloride is a dark brown solid, its physical characteristics are as follows: formula WCl4, molecular weight 325.65, density: 4.62g/ml. Tungsten tetrachloride’s hygroscopicity is not strong than tungsten pentachloride, but in the water it hydrolysis immediately. Even heating is not melting and sublimation, but if in a vacuum can be broken down when heated to reach the melting point. Tungsten tetrachloride synthesis processes are as follows:
1. Putting 20-25g tungsten hexachloride (making tungsten hexachloride excess 1-2g) and the calculated amount of an aluminum foil into boron silicate glass tube having a diameter of 30mm.
2. Then vacuum the reaction tube and closed. reaction tube at 475 ℃ heat preservation, containing tungsten hexachloride is maintained at 225 ℃.
3. After 48 hours reaction, the resulting tungsten tetrachloride can spread to the low temperature of the tube, setting out the rough crystal deposits.
4. During the reaction generated  excess tungsten hexachloride and aluminum chloride, which should be removed by heating the tube containing crystalline powder at 225 ℃, holding the other end of tube remain the room temperature. Then, open the reaction tube in a dry box to remove the tungsten tetrachloride.

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Tungsten hexachloride is an important raw material for new applications in many industries have been widely. For example, it is used as catalytic in the chemical industry, machinery industry’s production and repair, coating the surface of the glass industry and car glass industries. Its producing process is as follows:
1. Putting 100g tungsten trioxide (WO3) and 1L tungsten hexachloride into 2L round-bottomed flask, equipped with a reflux condenser with drying tube. After sufficiently stirring then heated until the tungsten trioxide reaction and completely dissolved which will need about 4h.
2. After cooling produce black crystals, in a dry box use a glass filter crystals, washed by dried carbon tetrachloride. Then use a vacuum pump with a trap to remove all organic solvent for 1 hour.
3. Putting metal tungsten powder into a quartz reaction tube as well as pumped in chlorine gas and reaction at 1000 ℃, then tungsten hexachloride sublimation and separate out at reaction tube cold area.
Before and after the reaction, the reaction tube and receiver inside’s air and chlorine should replace by inert gas completely. Because during the reaction if there has oxygen or moisture will easy to produce tungsten oxychlorine WCl2O2 and WOCl4. If there are above-described tungsten oxychlorine during the reaction, can be removed by heating, it is because they have larger volatile than tungsten hexachloride.

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The results of in situ temperature-resolved powder diffraction studies of CaWO₄ scheelite using both synchrotron radiation and neutron scattering are reported. The studies performed over a broad temperature range of 5-1773 K confirm the scheelite type of structure for calcium tungstate over the whole temperature range. The anisotropy of thermal expansion in calcium tungstate as well as the rigidity of WO₄ complexes have been analysed in terms of bond distances, interatomic angles and anisotropic displacement parameters. The WO₄^2- complex anions showed a remarkable robustness in the whole studied temperature range, thus pointing out that the layered structure formed by two-dimensional CsCl-type arrangements of Ca cations and WO₄ complexes is the primary reason for the anisotropy of thermal expansion in calcium tungstate.

 

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Tungsten hexachloride is a dark blue-purple crystal, and it is mainly used for plated tungsten by vapor deposition method and single crystal tungsten wire producing. Besides it also widely use in glass surface conductive layer, used as an olefin polymerization catalyst or organic synthesis and purification of tungsten.  Tungsten hexachloride is an important raw material for new applications, have been widely used in many industries. For example, it is widely used in chemical catalytic, mechanical industry production and repair and glass industry surface coating especially in car windows producing. Its physical characteristics are as follows: density: 3.52, melting point 275 ℃, boiling point 346 ℃, soluble in carbon disulfide, ether, ethanol, benzene, carbon tetrachloride, and easily decompose by water.
Tungsten hexachloride has some toxicity in the operation should pay attention to wear protective clothing if it exposed to the skin and eyes may result in irritation. What’s more it will caused serious pollution of water, so even a small amount of the tungsten hexachloride can not reach ground water, water course or sewage system, without government permission cannot released it to the environment.

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