- Microstructure and microwave dielectric properties of Ba5Nb4O15-BaWO4 composite ceramics
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Microwave dielectric composite ceramics with compositions of (1 - x)Ba5Nb4O15-xBaWO4 (x = 0-1) were prepared by firing the mixture of Ba5Nb4O15 and BaWO4. The sinterin
- Zhuang, Hao,Yue, Zhenxing,Zhao, Fei,Pei, Jing,Li, Longtu
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- Kinetics of formation of barium tungstate in equimolar powder mixture of BaCO3 and WO3: Thermogravimetric and spectroscopic studies
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The formation of Barium monotungstate (BaWO4) particles in equimolar powder mixtures of BaCO3 and WO3 was examined under isothermal and non-isothermal conditions upon heating in air at 25-1200 °C, using thermogravimetry. Concurrence of the observed mass loss (due to the release of CO2) to the occurrence of the formation reaction was evidenced. Accordingly, the extent of reaction (x) was determined as a function of time (t) or temperature (T). The x-t and x-T data thus obtained were processed using well established mathematical apparatus and methods, in order to characterize nature of reaction rate-determining step, and derive isothermal and non-isothermal kinetic parameters. Moreover, the reaction mixture quenched at various temperatures (600-1,000 °C) in the reaction course was analyzed by various spectroscopic and microscopic techniques, for material characterization. The results obtained indicated that the reaction rate may be controlled by unidirectional diffusion of WO3 species across the product layer (BaWO4), which was implied to form on the barium carbonate particles. The isothermally determined activation energy (118-125 kJ/mol) was found to be more credible than that (245 kJ/mol) determined non-isothermally.
- Al-Hajji, Latifa A.,Hasan, Muhammad A.,Zaki, Mohamed I.
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- Low-temperature properties of BaWO4 based on experimental heat capacity in the range 5.7–304u202fK
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The heat capacity of barium tungstate single crystal was measured by the adiabatic method in the range of 5.7–304 K. No anomalies in the heat capacity associated with the phase transition were found. The analysis of the functional behavior of heat capacity near zero revealed a low-frequency peak in the phonon density of states of BaWO4. An approach was proposed to allow quantitative description of the acoustic wing of the phonon density of states. The approximation of experimental data by an analytical expression was done, including the temperature region near 0 K. The Debye temperature at absolute zero has been obtained. The thermodynamic functions were calculated: entropy, enthalpy increment and Gibbs free energy.
- Musikhin,Bespyatov,Shlegel,Safonova
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- Engineering Polar Oxynitrides: Hexagonal Perovskite BaWON2
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Non-centrosymmetric polar compounds have important technological properties. Reported perovskite oxynitrides show centrosymmetric structures, and for some of them high permittivities have been observed and ascribed to local dipoles induced by partial order of nitride and oxide. Reported here is the first hexagonal perovskite oxynitride BaWON2, which shows a polar 6H polytype. Synchrotron X-ray and neutron powder diffraction, and annular bright-field in scanning transmission electron microscopy indicate that it crystalizes in the non-centrosymmetric space group P63mc, with a total order of nitride and oxide at two distinct coordination environments in cubic and hexagonal packed BaX3 layers. A synergetic second-order Jahn–Teller effect, supported by first principle calculations, anion order, and electrostatic repulsions between W6+ cations, induce large distortions at two inequivalent face-sharing octahedra that lead to long-range ordered dipoles and spontaneous polarization along the c axis. The new oxynitride is a semiconductor with a band gap of 1.1 eV and a large permittivity.
- Alemany, Pere,Canadell, Enric,Conejeros, Sergio,Cunquero, Marina,Fina, Ignasi,Fontcuberta, Josep,Frontera, Carlos,Fuertes, Amparo,Gàzquez, Jaume,Loza-Alvarez, Pablo,Oró-Solé, Judith,Ritter, Clemens
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- Low-temperature induced phase transitions in BaWO4:Er3+ microcrystals: A Raman scattering study
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The synthesis of rare-earth-doped barium tungstate has increased in recent decades due to the attractive electrical and optical properties of the material. In this study, erbium-doped barium tungstate was synthesized by the co-precipitation method with three different concentrations: Ba(1-x)ErxWO4 (where x = 0.00, 0.01, and 0.02). The materials were characterized by X-ray diffraction (XRD), Raman and Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Subsequently, the samples were subjected to temperature variations in the range of 123–293 K, and their Raman spectra were collected to observe the structural changes induced by Er doping. We observed that at low temperatures, there was no indication of phase transition for pure tungstate (BaWO4); however, for doped tungstates, changes were observed in the Raman spectra, showing an unexpected structural phase transition.
- Carvalho,Sousa,Matos,Moura,Freire,Pinheiro,Luz-Lima
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- Morphology-controlled synthesis of BaWO4 crystals via biominmetic SLM system
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BaWO4 crystals with various morphologies had been synthesized via a biominmetic system of supported liquid membrane in the presence of different additive reagents at room temperature. The X-ray diffraction patterns showed that the obtained BaWO
- Dong, Feng-Qiang,Wu, Qing-Sheng,Ding, Ya-Ping
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- Dielectric and tunable characteristics of Ba0.4Sr 0.6TiO3-BaWO4 composite ceramics for microwave applications
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Phase compositions, microstructure and microwave dielectric properties, of BaWO4 (BW)-Ba0.4Sr0.6TiO3 (BST) composite ceramics, prepared by the traditional solid-state route, were systematically characterized. Meanwhile, mechanism of dielectric tunability of those materials was discussed. Dielectric properties of the BW-BST composites at a DC bias field near the phase transition temperature could be interpreted by using Johnson's phenomenological equation. The sample with x = 0.60 exhibited a tunability of 29.5%, a dielectric permittivity of 192 and a Q value of 231 (at 2.700 GHz), which make it a promising candidate for applications in electrically tunable microwave devices.
- Zhang, Mingwei,Zhai, Jiwei,Shen, Bo,Yao, Xi
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- FORMATION OF A SERIES OF BARIUM TUNGSTEN BRONZES.
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The phases occurring in samples of gross composition Ba//xWO//3(0. 01 less than x less than 0. 33) heated at temperatures between 1073 and 1373 degree K have been determined using X-ray diffraction and electron microscopy. At all temperatures a tetragonal tungsten bronze phase with a narrow homogeneity range of x equals 0. 20-0. 21 was observed to form. In addition, at temperatures up to 1273 degree K, a series of orthorhombic intergrowth bronzes forms within a restricted composition range around x equals 0. 04. The latter phases are unstable at higher temperatures and were not found in preparations made at 1323 degree K. Similarly a new type of bronze phase forms at x equals 0. 14-0. 16 at temperatures up to 1323 degree K, but not at 1373 degree K. The structure of this phase is unknown. Aspects of the crystal chemistry of the barium bronzes and the relationships to other bronze phases are discussed.
- Ekstrom,Tilley
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- Visible light photocatalytic degradation of crystal violet dye and electrochemical detection of ascorbic acid & glucose using BaWO4 nanorods
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Barium tungstate (BaWO?) rod like nanostructures were synthesized by slightly modified hydrothermal technique using sodium tungstate dihydrate (Na2WO?. 2H2O) as tungstate ion source and barium nitrate [Ba(NO?)?] as barium ion source.
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- Low-temperature sintering and microwave dielectric properties of Ba 5Nb4O15-BaWO4 composite ceramics for LTCC applications
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Low-temperature-sintered composite ceramics in Ba5Nb 4O15-BaWO4 system were prepared by cofiring mixtures of Ba5Nb4O15 and BaWO4 powders. Thermo-mechanical analysis indicated that a small amount of B 2O3 addition significantly promoted the densification process and lowered the sintering temperature to ～900°C. X-ray diffraction analysis revealed that Ba5Nb4O15 and BaWO4 coexisted in the sintered ceramics. With increasing B 2O3 content, a secondary phase, BaNb2O 6, appeared which affects the microwave dielectric properties. Microwave dielectric properties of the aforementioned compositions were as follows: dielectric constant of 16.8-19.2, Q × f values of 33 900-50 300 GHz, and a temperature coefficient of the resonant frequency of -3.4 to -8.6 ppm/°C. The chemical compatibility of BNW6502 ceramics with silver during the cofiring process has also been investigated, and no evidence of chemical reaction between Ag and ceramics was observed, indicating that the as-prepared composite ceramics are suitable for low-temperature cofired ceramics applications.
- Zhuang, Hao,Yue, Zhenxing,Zhao, Fei,Li, Longtu
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- Luminescent properties under X-ray excitation of Ba(1?x)PbxWO4 disordered solid solution
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A series of polycrystalline barium-lead tungstate Ba1-xPbxWO4 with 0 ≤ x ≤ 1 was synthesized using a classical solid-state method with thermal treatment at 1000 °C. These materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Raman (FT-Raman) spectroscopy. X-ray diffraction profile analyses were performed using Rietveld method. These materials crystallized in the scheelite tetragonal structure and behaved as quasi ideal solid solution. Raman spectroscopy confirmed the formation of the solid solution. Structural distortions were evidenced in X-ray diffraction profiles and in vibration Raman spectra. The scanning electron microscopy experiments showed large and rounded irregular grains. Luminescence experiments were performed under X-ray excitation. The luminescence emission profiles have been interpreted in terms of four Gaussian components, with a major contribution of blue emission. The integrated intensity of luminescence reached a maximum value in the composition range x = 0.3–0.6, in relation with distortions of crystal lattice.
- Bakiz,Hallaoui,Taoufyq,Benlhachemi,Guinneton,Villain,Ezahri,Valmalette,Arab,Gavarri
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- Reactivity of solid BaCe0.9Y0.1O3-δ towards melted WO3
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High-temperature impregnation of solid single-phase Y-doped BaCeO3 with melted WO3 was performed towards the evaluation of the possibility of formation of chemically stable material with relatively high electrical conductivity in this system. Impregnation was performed at 1470 °C as a function of time. Due to the relatively high reactivity in solid BaCe0.9Y0.1O3-δ - liquid WO3 system the reactive and the inner layers were distinguished and analysed. The obtained results clearly indicate the decomposition of Y-doped BaCeO3 in contact with melted WO3. X-ray diffraction method together with SEM observation, EDS analysis and EIS measurements results were applied to discuss the mechanism of this multi-stage process and the influence of the reaction time on materials structure and microstructure. As it was observed, partial incorporation of tungsten into the barium cerate structure can process not only on the surface of the materials but also in the inner layer of the synthesised materials. This donor-type doping of the perovskite structure finds reflection in both, materials electrical properties and chemical stability towards CO2/H2O. The decrease of proton defects concentration was observed together with the significant increase of the materials chemical stability in comparison to un-modified single-phase BaCe0.9Y0.1O3-δ. The calculated values of activation energy of conductivity confirm the change in the conduction mechanism. Also, the presence of an additional phase in the intergranular voids of doped BaCeO3 was postulated.
- Lacz, Agnieszka,Okas, Paulina,Lach, Radoslaw
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- Polymer-directed synthesis of penniform BaWO4 nanostructures in reverse micelles
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Novel penniform superstructures of BaWO4 nanowires have been successfully synthesized in catanionic reverse micelles by using a double-hydrophilic block copolymer as the directing agent. This synthetic method is very simple, mild, and controllable, and it provides a novel method for direct solution-growth of hierarchical nanostructures based on inorganic nanowires. Copyright
- Shi, Hongtao,Qi, Limin,Ma, Jiming,Cheng, Humin
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- Low-temperature sintering and microwave dielectric properties of Ba 3(VO4)2-BaWO4 ceramic composites
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New low-temperature co-fired microwave dielectric composites with compositions of (1-x)Ba3(VO4)2-xBaWO 4 (x=0-1) were prepared by firing mixtures of Ba3(VO 4)2 and BaWO4. Thermal mechanical analysis indicated the ceramic composites had relatively low densification temperatures and could be sintered in the temperature range 925°～950°C. X-ray diffraction patterns showed that Ba3(VO4)2 and BaWO4 coexisted and no secondary phase was detected in the sintered bodies, implying good chemical compatibility between the two phases. Near-zero temperature coefficients of the resonant frequency (τf) could be achieved by changing the relative content of the two phases, due to their positive and negative τf values, respectively. With increasing BaWO4 (x from 0.50 to 0.65), the τf value of the composites decreased from +10.9 to -1.9 ppm/°C, and the quality factor (Q × f value) increased from 66 700 to 79 100 GHz. The best microwave dielectric properties were obtained for x=0.65 samples sintered at 925°C with a dielectric constant of 11.1, a Q × f value of 79 100 GHz, and a τf value of -1.9 ppm/°C. Chemical compatibility experiments showed the ceramics are compatible with silver during cofiring process.
- Zhuang, Hao,Yue, Zhenxing,Meng, Siqin,Zhao, Fei,Li, Longtu
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- General, room-temperature method for the synthesis of isolated as well as arrays of single-crystalline ABO4-type nanorods
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Single-crystalline BaWO4 and BaCrO4 nanorods of reproducible shape and of varying sizes have been controllably prepared using a simple, room-temperature approach, based on the use of porous alumina template membranes. Aligned BaWO4 and BaCrO4 nanorod arrays can be obtained by dissolving the template. Our facile technique, which is analogous to biomineralization, offers a promising and generalized methodology to prepare other types of free-standing ABO4 nanorods and their corresponding nanorod arrays. Extensive characterization of these samples has been performed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS), selected area electron diffraction (SAED), Raman spectroscopy, FT-infrared spectroscopy (FT-IR), and X-ray diffraction (XRD).
- Mao, Yuanbing,Wong, Stanislaus S.
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- Cyclic microwave synthesis and photoluminescence of barium tungstate particles assisted by a solid-state metathetic reaction
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Barium tungstate (BaWO4) particles were synthesized successfully using a solid-state metathetic route assisted by a cyclic microwave irradiation. Well-crystallized BaWO4 particles were formed at 400-600 °C for 3 h, showing fine and homogeneous morphologies with particle sizes of 1-2 μm. The synthesized BaWO4 particles were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. The optical properties were investigated by photoluminescence emission and Raman spectroscopy.
- Lim, Chang Sung
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- Serendipitous discovery of super adsorbent properties of sonochemically synthesized nano BaWO4
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The superior adsorbent properties of BaWO4 nanostructures have been reported for the first time. Flower shaped aggregates (～250 nm) of BaWO4 nanoparticles, having an average size of ～10-15 nm with a high surface area of ～148.0 ± 0.2 m2 g-1, have been synthesized sonochemically and used for the adsorption of various cationic dyes from aqueous solutions. The sonochemically synthesized BaWO4 have been characterized by scanning electron microscopy (SEM), selected area electron diffraction (SAED), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectra (FTIR). The adsorbent capacity of this tungstate is much higher than that reported for other nanomaterials like Fe2O3, MnO2, WO3, etc. Complete removal of dyes like rhodamine B and methylene blue was possible within a short time span of 10-15 minutes. The adsorption process was followed using UV-Visible spectroscopy, while the material before and after adsorption has been characterized using physicochemical and spectroscopic techniques. Various isotherms have been used to fit the data, and kinetic parameters were evaluated. Moreover, the adsorbed dyes could be desorbed completely from nanoparticle surfaces by annealing at moderate temperature and were found to be efficient for multicyclic use. Thus this sonochemically synthesized nano BaWO4 has great significance in treatment of dye industry effluents as a promising adsorbent for cationic dyes from aqueous solution. The Royal Society of Chemistry 2013.
- Singh, Anamika,Dutta, Dimple P.,Ramkumar, Jayshree,Bhattacharya, Kaustav,Tyagi, Avesh Kumar,Fulekar
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- Structure and calorimetric study of complex oxides based on lanthanum, tungsten, and alkaline earth elements MeLa2WO7 (Me = Mg, Ca, Sr, Ba)
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As a result of citrate synthesis by the “sol–gel” method, we obtained samples of the compounds of ternary oxides with lanthanum, tungsten, and alkaline earth elements with the general formula MeLa2WO7 (Me = Mg, Ca, Sr, Ba). The structure of the samples obtained was studied by the X-ray diffraction, electron probe, and X-ray spectral microanalysis; the infrared and Raman spectra of the compounds were obtained. The results of indexing for SrLa2WO7 and BaLa2WO7 are in good agreement with the previously published crystallographic data. The heat capacity of the samples was measured by using of adiabatic calorimetry and their thermodynamic functions were calculated.
- Bissengaliyeva, Mira R.,Zhakupov, Ramazan M.,Knyazev, Alexander V.,Gogol, Daniil B.,Taimassova, Shynar T.,Balbekova, Bakhyt K.,Bekturganov, Nuraly S.
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p. 2287 - 2301
(2020/01/28)
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- Host composition dependent tuneable morphology and luminescent property of the CaXSrYBa1?X?YWO4:RE3+(RE=Pr, Ho, and Er) phosphors
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Novel Pr3+, Ho3+, and Er3+single-doped CaXSrYBa1?X?YWO4phosphors were successfully prepared via a facile hydrothermal method. The hydrothermal process was conducted in aqueous condition without the use of any organic solvent, surfactant, or catalyst. The effects of doping-host composition and RE3+doping concentration on the emission intensity were investigated to optimize the luminescent properties of CaXSrYBa1?X?YWO4:RE3+phosphors. Experimental results demonstrate that the morphologies of the products vary gradually and regularly with the change of the host composition, in which the anisotropic growth played a key role. Moreover, the down-conversion emissions of Pr3+, Ho3+, and Er3+in CaXSrYBa1?X?YWO4host were successfully realized. After optimizing the luminescent properties, Ca0.4Sr0.6WO4:0.01Pr3+, Ca0.8Sr0.2WO4:0.01Ho3+, and Ca0.6Sr0.4WO4:0.005Er3+exhibited optimal luminescent property, with orange, yellowish-green, and green emissions, respectively.
- Li, Linlin,Wu, Hong-Yue
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p. 106 - 119
(2017/02/05)
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- Raman studies of A2MWO6 tungstate double perovskites
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The Raman spectra of seven A2MWO6 tungstate double perovskites are analysed. Ba2MgWO6 is a cubic double perovskite with Fm3m symmetry and its Raman spectrum contain three modes that can be assigned in a straightforward manner. A fourth mode, the asymmetric stretch of the [WO6]6- octahedron, is too weak to be observed. The symmetry of Ba2CaWO6 is lowered to tetragonal I4/m due to octahedral tilting, but the distortion is sufficiently subtle that the extra bands predicted to appear in the Raman spectrum are not observed. The remaining five compounds have additional octahedral tilts that lower the symmetry to monoclinic P21/n. The further reduction of symmetry leads to the appearance of additional lattice modes involving translations of the A-site cations and librations of the octahedra. Comparing the Raman spectra of fourteen different A2MWO6 tungstate double perovskites shows that the frequency of the symmetric stretch (ν1) of the [WO6]6- octahedron is relatively low for cubic perovskites with tolerance factors greater than one due to underbonding of the tungsten and/or M cation. The frequency of this mode increases rapidly as the tolerance factor drops below one, before decreasing gradually as the octahedral tilting gets larger. The frequency of the oxygen bending mode (ν5) is shown to be dependent on the mass of the A-site cation due to coupling of the internal bending mode with external A-site cation translation modes.
- Andrews,Heyns,Woodward
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p. 10700 - 10707
(2015/06/16)
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- Scheelite-type MWO4 (M = Ca, Sr, and Ba) nanophosphors: Facile synthesis, structural characterization, photoluminescence, and photocatalytic properties
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Scheelite-type MWO4 (M = Ca, Sr, and Ba) nanophosphors were synthesized by the precipitation method. All compounds crystallized in the tetragonal structure with space group I41/a (No. 88). Scherrer's and TEM results revealed that the average crystallite size varies from 32 to 55 nm. FE-SEM illustrate the spherical (CaWO4), bouquet (SrWO4), and fish (BaWO4) like morphologies. PL spectra indicate the broad emission peak maximum at 436 (CaWO4), 440 (SrWO4), and 433 nm (BaWO4) under UV excitation. The calculated CIE color coordinates of MWO4 nanophosphors are close to the commercial BAM and National Television System Committee blue phosphor. The photocatalytic activities of MWO4 were investigated for the degradation of methylene blue dye under UV illumination. At pH 3, BaWO4 nanocatalyst showed 100% dye degradation within 60 min. The photocatalytic activity was in the decreasing order of BaWO4 > CaWO4 > SrWO4 under both neutral and acidic conditions.
- Shivakumara,Saraf, Rohit,Behera, Sukanti,Dhananjaya,Nagabhushana
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p. 422 - 432
(2015/02/19)
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- Dielectric and microstructural study of the SrWO4, BaWO 4, and CaWO4 scheelite ceramics
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MWO4 (M=Ca, Sr and Ba) scheelite ceramics were studied in terms of their syntheses, sintering, solubility in water, and dielectric response after storing them in dry and moist atmospheres. Of the studied scheelites, the CaWO4 possessed the most promising dielectric properties (ε=10.9, Q × f=105 600 GHz), which were stable under the influence of humidity. BaWO4 and SrWO4 exhibited ε=9.0 and Q × f values of 32 200 and 62 600 GHz, respectively. The most detrimental effect of the moisture was observed for SrWO4. A sodium impurity present in the SrCO3 reagent (0.35 wt%), which was used for the synthesis of the SrWO4, was found to lower the sintering temperature, enhance the grain growth, and change the other properties of the ceramics, such as humidity susceptibility and solubility in water. The evident tendency of the ceramics to attract water and the increased dissolution of tungstate were observed for all MWO4 scheelite ceramics, which were sintered with the help of Na2CO3 or Li2CO3 (0.5 wt%) sintering aids. The results of the present study suggest that the physical and chemical properties of the ceramics should be carefully considered in the case of using of alkaline-containing sintering aids.
- Krzmanc, Marjeta MacEk,Logar, Manca,Budic, Bojan,Suvorov, Danilo
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p. 2464 - 2472
(2011/12/22)
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- Barium molybdate and barium tungstate nanocrystals synthesized by a cyclic microwave irradiation
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BaMoO4 and BaWO4 nanocrystals were synthesized from Ba(NO3)2 and Na2MeO4 (Me=Mo and W) solutions using 50% of 600 W microwave irradiation for 20 min. The products were characterized using X
- Phuruangrat, Anukorn,Thongtem, Titipun,Thongtem, Somchai
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p. 955 - 959
(2009/10/17)
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- Structure-dependent photocatalytic activities of MWO4 (M = Ca, Sr, Ba)
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The photocatalytic activities of the isostructural photocatalysts MWO4 (M = Ca, Sr, Ba) for decomposing methyl orange, which were synthesized by a solid state reaction, were investigated. In the experiments, the photocatalytic activity is in th
- Shan, Zhichao,Wang, Yaoming,Ding, Hanming,Huang, Fuqiang
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- Synthesis and characterization of metal tungstates by novel solid-state metathetic approach
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Novel solid state metathetic approach (SSM) (ACl2 + Na2WO4 → AWO4 + 2NaCl, A = Ca, Sr, Ba, Zn, Mn, Ni) assisted by microwave energy has been successfully applied to the synthesis of tungstates of scheelite- and wolframite-type that are of technological importance. Well crystalline phases of scheelite-type tungstates, MWO4 (M = Ca, Sr, Ba) have been synthesized where the characteristics of SSM reaction and the formation of high lattice energy by-product NaCl drives the reaction toward completion. Among wolframite-type tungstates, single-phase ZnWO4 is synthesized by SSM reactions at ambient conditions and MWO4 (M = Ni, Mn) are synthesized after subjecting the amorphous product to moderate temperature of heating (around 500 °C for 6 h). This alternative method of synthesis where the metathesis reactions proceed in solid state has features like: simple method of synthesis, cost-effectiveness, high yield, easy scale up, and thus has advantages over already known methods of synthesis.
- Parhi, Purnendu,Karthik,Manivannan
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p. 380 - 386
(2009/02/07)
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- TiO2 controlling photoluminescence of AWO4 (A=Ca, Sr, Ba) nanofilms
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AWO4 (A=Ca,Sr,Ba) nanofilms are prepared by a self-inventive technique using collodion to disperse nanoparticles and form film, and their photoluminescence (PL) properties are controlled by a nano-TiO2 doping method. This cannot only reach the results of uniform film and PL enhancement, but also realize a PL increase/decrease shift effect. The PL behaviors of AWO4 nanofilms doped by TiO2 are in good agreement with Gaussion function relation. In addition, there is a positive correlation between the critical concentrations of TiO2 in AWO 4-TiO2 nanofilm series and A's ionic potential.
- Jia, Runping,Zhang, Guoxin,Wu, Qingsheng,Ding, Yaping
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- Synthesis of alkaline-earth metal tungstates in melts of [NaNO 3-M(NO3)2]eut-Na2WO 4 (M = Ca, Sr, Ba) systems
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Alkaline-earth metal tungstates are synthesized in NaNO 3-M(NO3)2 (M = Ca, Sr, Ba) eutectic melts. The synthesis is based on the exchange reaction of calcium, strontium, or barium nitrate with sodium tungstate. Pleiades Pu
- Shurdumov,Shurdumova,Cherkesov,Karmokov
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p. 531 - 532
(2008/10/09)
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- Enthalpies of formation from the component oxides of MgWO4, CaWO4 (scheelite), SrWO4, and BaWO4, determined by high-temperature direct synthesis calorimetry
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The enthalpies of formation, from the constituent oxides, of tungstates of alkaline earth metals, MeWO4(Me is Mg, Ca, Sr, Ba), have been determined by direct synthesis calorimetry at 1473 ± 2 K. The following values of ΔHf at 298 K (
- Guo, Qiti,Kleppa, Ole Jakob
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