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7790-75-2

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7790-75-2 Usage

Chemical Properties

-325 mesh, 10μm or less 99.9% pure; occurs in nature as mineral scheelite; white tetr powder(s), a=0.524 nm, c=1.138 nm; can be prepared by heating tungstic acid and CaO or CaCO3; used in tumor treatment and in luminous paint [KIR83] [STR93] [MER06]

Uses

Different sources of media describe the Uses of 7790-75-2 differently. You can refer to the following data:
1. Calcium tungsten oxide is used as a luminophore.
2. Calcium tungstate can be ued for preparing screens for x-ray observations and photographs; in luminous paints; in scintillation counters.

General Description

Calcium tungstate (CaWO4) is an optical material, which can be used as a laser host material for a variety of electronic applications. It has a scheelite structure with luminescence, and thermo-luminescence properties.

Flammability and Explosibility

Notclassified

Check Digit Verification of cas no

The CAS Registry Mumber 7790-75-2 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 7,7,9 and 0 respectively; the second part has 2 digits, 7 and 5 respectively.
Calculate Digit Verification of CAS Registry Number 7790-75:
(6*7)+(5*7)+(4*9)+(3*0)+(2*7)+(1*5)=132
132 % 10 = 2
So 7790-75-2 is a valid CAS Registry Number.
InChI:InChI=1/Ca.4O.W/q+2;;;2*-1;/rCa.O4W/c;1-5(2,3)4/q+2;-2

7790-75-2 Well-known Company Product Price

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  • Alfa Aesar

  • (13051)  Calcium tungsten oxide, 98%   

  • 7790-75-2

  • 25g

  • 359.0CNY

  • Detail
  • Alfa Aesar

  • (13051)  Calcium tungsten oxide, 98%   

  • 7790-75-2

  • 100g

  • 643.0CNY

  • Detail
  • Alfa Aesar

  • (13051)  Calcium tungsten oxide, 98%   

  • 7790-75-2

  • 500g

  • 2605.0CNY

  • Detail
  • Alfa Aesar

  • (35669)  Calcium tungsten oxide, 99.78% (metals basis)   

  • 7790-75-2

  • 50g

  • 1110.0CNY

  • Detail
  • Alfa Aesar

  • (35669)  Calcium tungsten oxide, 99.78% (metals basis)   

  • 7790-75-2

  • 250g

  • 4719.0CNY

  • Detail
  • Aldrich

  • (248665)  Calciumtungstate  powder

  • 7790-75-2

  • 248665-100G

  • 1,627.47CNY

  • Detail
  • Aldrich

  • (248665)  Calciumtungstate  powder

  • 7790-75-2

  • 248665-500G

  • 5,798.52CNY

  • Detail

7790-75-2SDS

SAFETY DATA SHEETS

According to Globally Harmonized System of Classification and Labelling of Chemicals (GHS) - Sixth revised edition

Version: 1.0

Creation Date: Aug 17, 2017

Revision Date: Aug 17, 2017

1.Identification

1.1 GHS Product identifier

Product name Calcium tungsten oxid

1.2 Other means of identification

Product number -
Other names Calcium tungstate

1.3 Recommended use of the chemical and restrictions on use

Identified uses For industry use only.
Uses advised against no data available

1.4 Supplier's details

1.5 Emergency phone number

Emergency phone number -
Service hours Monday to Friday, 9am-5pm (Standard time zone: UTC/GMT +8 hours).

More Details:7790-75-2 SDS

7790-75-2Downstream Products

7790-75-2Relevant articles and documents

Synthesis of Tungstate Thin Films and Their Optical Properties

Saito, Nobuhiro,Kudo, Akihiko,Sakata, Tadayoshi

, p. 1241 - 1245 (1996)

A simple and new synthetic method of tungstate thin films (CaWO4, MgWO4, PbWO4, ZnWO4) was developed. The absorption and luminescence spectra of tungstate thin films synthesized on quartz substrates were measured; the optical properties were also studied. It was found that CaWO4 has Eg = 5.4 eV of a direct transition nature. Tungstate thin films were strongly luminescent when irradiated with UV-light. Excitation at around 290 nm was interpreted as a singlet-triplet transition.

An efficient near infrared photocatalyst of Er3+/Tm3+/Yb3+tridoped (CaWO4at(TiO2/CaF2)) with multi-stage CaF2nanocrystal formation

Huang, Shouqiang,Lou, Ziyang,Shan, Aidang,Zhu, Nanwen,Feng, Kaili,Yuan, Haiping

, p. 16165 - 16174 (2014)

The formation process of CaF2is critical for the improvement of upconversion properties of the CaF2based upconversion photocatalysts, and for this purpose a near-infrared (NIR) photocatalyst of Er3+/Tm3+/Yb3+tridoped (CaWO4at(TiO2/CaF2)) (ETY-CTC) was synthesized. CaF2nanocrystals are converted from CaWO4precursors in a multi-stage process, and the remaining CaWO4microspheres are wrapped in CaF2and TiO2nanocrystals to form the heterostructure of the photocatalyst. CaF2is found to connect with TiO2nanocrystals, instead of being coated by TiO2, resulting in a higher upconversion luminescence efficiency of ETY-CTC than that of pure Er3+/Tm3+/Yb3+tridoped (CaWO4@CaF2). ETY-CTC possesses higher photocatalytic activities compared to Er3+/Tm3+/Yb3+tridoped (CaWO4@TiO2) under NIR and UV-vis-NIR light irradiations, since more OH and O2-radicals, and higher electron-hole separation efficiency are obtained in the ETY-CTC system. The multi-stage formation of luminescence agents can be an attractive method for the synthesis of NIR photocatalysts with enhanced upconversion properties and photocatalytic activities. This journal is

Effect of noble metal element on microstructure and NO2 sensing properties of WO3 nanoplates prepared from a low-grade scheelite concentrate

Li, Tingting,Shen, Yanbai,Zhong, Xiangxi,Zhao, Sikai,Li, Guodong,Cui, Baoyu,Wei, Dezhou,Wei, Kefeng

, (2020)

To break the limitation of raw materials for preparing functional WO3 nanomaterials, a low-grade scheelite concentrate was selected as the tungsten source, and WO3 nanoplates doped with Ag, Pd, Au and Pt were synthesized through three combined processes including NaOH leaching, chemical precipitation and acidification. The microstructure and NO2 sensing properties of pure and noble metal-doped WO3 nanoplates were investigated. The microstructure characterization demonstrated that all WO3 products were composed of interlaced and irregular nanoplates with the thickness of 10–30 nm, and the length and width of these nanoplates were in the range of several hundred nanometers. NO2 sensing properties indicated that WO3 nanoplates doped with noble metal nanoparticles exhibited obviously higher responses and shorter response times than pure WO3 nanoplates. Especially, noble metal-doped WO3 nanoplates exhibited distinct behaviors in terms of the enhancement of sensing properties. Pd-doped WO3 nanoplates exhibited highest response to NO2, and Ag-doped WO3 nanoplates exhibited fastest response speed. Additionally, Ag-, Pd- and Pt-doped WO3 nanoplates exhibited a relatively lower optimal operating temperature. The enhanced NO2 sensing performance can be ascribed to the large specific surface area of WO3 nanoplates, the catalytic activities of noble metal nanoparticles, and the varied work function energies together with the lower activation energies.

Synthesis and characterization of Ag+ and Zn2+ co-doped CaWO4 nanoparticles by a fast and facile sonochemical method

Neto, N.F. Andrade,Dias,Tranquilin,Longo,Li,Bomio,Motta

, (2020)

In this work, Ag+ and Zn2+ co-doped CaWO4 nanoparticles were obtained by fast and facile sonochemical method. The nanoparticles were characterized by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), visible ultraviolet spectroscopy (UV–Vis) and photoluminescence property. The photocatalytic activity was studied against methylene blue (MB) dye under sunlight and CaWO4 powders were tested in 3 reuse cycles. The diffractograms indicate the non-formation of secondary phases and the Rietveld refinement estimated the crystallite sizes, being 27.38, 19.89, 18.70 and 16.39 nm for the pure, Ag, Zn and Ag:Zn samples, respectively. SEM and TEM images showed that the particles are agglomerated and have a mean diameter ranging from 16.76 (Ag:Zn) to 71.76 nm (pure). Defects generated by doping shift the gap band to higher energies and act to prevent electron/hole (e?/h+) pair recombination, reducing photoluminescence and favoring CaWO4 photocatalysis. Scavenger methodology indicated that h+ is the main mechanism acting in photocatalysis, and the reuse tests indicated that the silver-doped sample, even with the better initial response, loses efficiency over the course of the cycle, while the co-doped sample maintains efficiency, and is therefore indicated for reuse photocatalysis applications in methylene blue dye degradation.

Double Double to Double Perovskite Transformations in Quaternary Manganese Oxides

Ji, Kunlang,Alharbi, Khalid N.,Solana-Madruga, Elena,Moyo, Gessica T.,Ritter, Clemens,Attfield, J. Paul

, p. 22248 - 22252 (2021)

Control of cation ordering in ABX3 perovskites is important to structural, physical and chemical properties. Here we show that thermal transformations of AA′BB′O6 double double perovskites, where both A and B sites have 1:1 cation order, to (A0.5A′0.5)2BB′O6 double perovskites with fully disordered A/A′ cations can be achieved under pressure in CaMnMnWO6 and SmMnMnTaO6, enabling both polymorphs of each material to be recovered. This leads to a dramatic switch of magnetic properties from ferrimagnetic order in double double perovskite CaMnMnWO6 to spin glass behaviour in the highly frustrated double perovskite polymorph. Comparison of double double and double perovskite polymorphs of other materials will enable effects of cation order and disorder on other properties such as ferroelectricity and conductivity to be explored.

Luminescence properties of europium-terbium double activated calcium tungstate phosphor

Nazarov,Jeon,Kang,Popovici,Muresan,Zamoryanskaya,Tsukerblat

, p. 307 - 311 (2004)

Double incorporation of Eu3+ and Tb3+ ions into a CaWO4 crystalline lattice modifies the luminescence spectrum due to the formation of new emission centers. Depending on the activators concentration and nature, as well as on the interaction between the activators themselves, the luminescence color can be varied within the entire range of the visible spectrum. Variable luminescence was obtained when CaWO4:Eu,Tb phosphors with 0-5mol% activator ions were exposed to relatively low excitation energies as UV (365 and 254 nm). Under high energy excitation such as VUV (147 nm) radiation or electron beam, white light has been observed. This material with controlled properties seems to be promising for the applications in fluorescent lamps, colored lightning for advertisement industries, and other optoelectronic devices.

Electronic structure, optical and sonophotocatalytic properties of spindle-like CaWO4 microcrystals synthesized by the sonochemical method

Cavalcante, L. S.,Gouveia, A. F.,Longo, E.,Nogueira, I. C.,San-Miguel, M. A.,Sczancoski, J. C.,de Sousa, P. B.

, (2021)

In this letter, the electronic structure, optical, and sonophotocatalytic properties of calcium tungstate (CaWO4) microcrystals synthesized by the sonochemical method are reported. Structural and morphological characterization techniques revealed that CaWO4 has a tetragonal structure and composed of several spindle-like microcrystals. The ultraviolet–visible spectroscopy showed an optical band gap energy Egap(exp) of 4.69 eV. The theoretical calculations were performed to describe the electronic band structure, the density of states, and Infrared/Raman vibrational modes. The theoretical models were based on optimized and defect-based structures. The theoretical optical band gap energy (Egap) confirmed the existence of direct electronic transitions (Γ?Γ points in Brillouin zone). The optimized structure exhibited an Egap(theo) value of 5.70 eV due to the participation of energy levels arising from O and Ca atoms in the valence band as well as W and O atoms in the conduction band. A decrease from 5.70 to 4.29 eV was observed for the defect-based structure. The sonophotocatalytic properties of CaWO4 microcrystals were investigated for the first time with respect to degradation of Rhodamine B dye and they revealed a degradation capacity of approximately 96% after 200 min. Finally, our electron density maps indicate that the presence of structural defects induces a polarization phenomenon and inhomogeneous distribution of electron charge between the [CaO8]–[WO4] clusters.

Inagaki, M.,Kotera, Y.,Sekine, T.

, p. 1303 - 1310 (1983)

Tungstates: Novel heterogeneous catalysts for the synthesis of 5-substituted 1H-tetrazoles

He, Jinghui,Li, Baojun,Chen, Fasheng,Xu, Zheng,Yin, Gui

, p. 135 - 138 (2009)

Most heterogeneous catalysts utilized for the formation of 5-substituted 1H-tetrazoles contain zinc as the metal core at the catalytically active site. In this paper, we report that the tungstate MWO4 (M = Ba, Ca, Zn, Cd, Cu, Na, H) can catalyz

Red-emitting enhancement by inducing lower crystal field symmetry of Eu3+ site in CaWO4:Eu3+ phosphor for n-UV w-LEDs

Xia, Minfang,Ju, Zhenghua,Yang, Huan,Wang, Zhenbin,Gao, Xiuping,Pan, Fuxing,Liu, Weisheng

, p. 439 - 446 (2018)

A series of enhanced red-emitting phosphors Ca1-x-yMgxSryWO4:zEu3+ (x = 0.00–0.30, y = 0.00–0.12, z = 0.00–0.16) were successfully synthesized via a high temperature solid-state reaction method. The phase structure, photoluminescence properties and thermal stability were investigated detailedly. All as-prepared samples, especially Ca0.65Mg0.20Sr0.05WO4:0.10Eu3+ phosphors exhibit an extremely enhanced red emission peaking at 616 nm originating from 5D0―7F2 transition of Eu3+ under the 392 nm n-UV excitation. Mg2+ and Sr2+ were introduced into CaWO4:0.10Eu3+ to induce crystallographic parameters and crystal symmetry changes of Eu3+ ions in CaWO4 host. Enhanced red emission, broadband excitation spectra (from 200 to 600 nm), strong ultraviolet absorption matched well with n-UV LEDs chips (350–420 nm) and high color purity (the R/O value is up to 7.52) indicate that as-prepared Ca0.65Mg0.20Sr0.05WO4:0.10Eu3+ sample can be a potential candidate red phosphor for n-UV white light-emitting diodes.

The interface transport of V2O5 and WO3 into CaMo(W)O4 stimulated by an electric field

Guseva,Neiman,Konisheva,Trifonova,Gorbunova

, p. 140 - 145 (2002)

An electric field applied to the CaWO4/V2O5, CaMoO4/V2O5 and CaMoO4/WO3 systems causes grain boundary and surface transports of oxides having a low surface energy (V2O5 and WO3) and their segregation on the grain surface. It was found that V2O5 penetrates to the inner surface of CaWO4 much more intensively when the V2O5 briquette bears a negative potential: (-)V2O5|CaWO4(+). The penetration of V2O5 and WO3 to the inner surface of the CaMoO4 ceramic is accompanied by a chemical interaction.

Spectroscopic properties and intense red-light emission of (Ca, Eu, M)WO4 (M = Mg, Zn, Li)

Shi, Shikao,Liu, Xingren,Gao, Jing,Zhou, Ji

, p. 396 - 399 (2008)

The red-emitting phosphors of (Ca, Eu, M)WO4 (M = Mg, Zn, Li) were prepared through solid-state reactions, and their spectroscopic properties were studied. After the addition of a small amount of Mg2+, Zn2+ or Li+ in (Ca, Eu)WO4, the red-light emission intensity of Eu3+ increases obviously. In the luminescence spectra of the phosphors, the predominant transition emission is 5D0 → 7F2 (616 nm), whereas the other emissions are very weak. The excitation spectra are composed of interweaved ligand-to-metal charge-transfer bands (CTB) of W6+-O2- and Eu3+-O2-, and a few 4f excitation transitions of Eu3+. Among the 4f excitation transitions of Eu3+, there are three strong excitation lines corresponding to 7F0 → 5L6, 7F0 → 5D2 and 7F0 → 5D1 transitions, whose relative excitation intensity ratio is seriously affected when Li+ doped in the host. The new phosphors may be applied as red-emitting phosphors for white light emitting diodes.

Controlled synthesis and room-temperature ferromagnetism of CaWO4 nanostructures

Sun,Jia,Wu,Chen

, p. 95 - 99 (2015)

CaWO4 nanostructures (nanospheres, nanorods and nanoplates) were synthesized by a hydrothermal process. The morphology, size and composition of these nanostructures were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray energy dispersive spectroscopy (EDS). Based on the electron microscope observations, the growth of such nanostructures has been proposed as an Ostwald ripening process followed by self-assembly. Furthermore, magnetic measurement of these CaWO4 nanostructures indicates as-prepared CaWO4 nanostructures possess obvious room-temperature ferromagnetism, suggesting the potential of CaWO4 nanostructures in applications.

Microstructure and optical properties of nanocrystalline CaWO4 thin films deposited by pulsed laser ablation in room temperature

Ryu, Jeong Ho,Bang, Sin Young,Kim, Woo Sik,Park, Gyeong Seon,Kim, Kang Min,Yoon, Jong-Won,Shim, Kwang Bo,Koshizaki, Naoto

, p. 146 - 151 (2007)

Nanocrystalline CaWO4 films were successfully deposited by pulsed laser ablation at various background Ar gas pressures (10-100 Pa) without substrate heating or after annealing treatment. The effects of Ar pressure on microstructure, surface morphology, chemical composition and optical properties were investigated by XRD, HR-TEM, FE-SEM, XPS, UV-vis and PL analyses. The crystallite size of CaWO4 films increased with increasing Ar pressure, which was associated with a change of surface morphology. Reduced tungsten states [W5+] or [W4+] caused by oxygen vacancies were observed at 10 Pa. However, over 50 Pa, the atomic concentration of all the constituent elements was almost constant, especially [Ca]/[W] ratio, which was nearly unity. The optical energy band-gap of CaWO4 films was strongly dependent on the Ar pressure, i.e., decreased from 4.9 to 4.5 eV with the increase of Ar pressure from 50 to 100 Pa. The photoluminescence (PL) spectra was positioned in a blue-shifted region around 378 nm compared with emission at 420 nm of bulk CaWO4 target, which clearly demonstrates the optical band-gap widening phenomena induced by quantum-size effect.

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