It is isostructural to the scheelite structure (CaWO 4) and is composed of [MoO 4] 2− tetra­hedra with symmetry and [(Na/Er)O 8] 14− polyhedra. The [(Na/Er)O 8] 14− polyhedron is a distorted tetra­gonal anti­prism, also with symmetry, with statistically mixed Na/Er atoms at its centre. There are two sets of Na/Er—O bond lengths [2 ...

The determination of the Raman spectrum above 13 GPa was hindered by the persistence of the scheelite structure and the darkening of the sample. The Raman spectrum of the high-pressure phase is similar to that of the scheelite phase, except for the appearance of two modes in the gap of the frequency spectrum between the lattice and the internal ...

A number of metal oxides that crystallise in the scheelite structure type are known to be excellent oxide ion conductors. Here we report the synthesis of a series of materials with general formula LaNb1−xMoxO4+0.5x (x = 0, 0.08, 0.12, 0.16, 0.20) and excellent oxide-ionic conductivity for x ≥ 0.16 (7.0 × 10− Recent Open Access Articles

1. a catalyst which has scheelite-type crystal structure of the formula a1-z&z bo4 wherein a represents cations having ionic radii in the range of about 0.9 to about 1.6 *a, some of which are trivalent bismuth, and at least one other is selected from the group consisting of lead, calcium, strontium, barium, zirconium and hafnium; b represents cations having ionic radii in the range of about 0 ...

scheelite structure is much higher than that of the other two[7]. Therefore, the phase structure is an important factor to the photocatalytic performance. In order to confirm the phase structure of as-synthesized samples, the XRD patterns were measured and shown in Fig.1.

The TCF of BiVO 4 with monoclinic scheelite structure is −260 ppm/°C [14,15]. The monoclinic scheelite BiVO 4 is ferroelastic at room temperature and reversibly transforms to paraeleastic BiVO 4 with a standard tetragonal scheelite structure (space group I4 …

Both tetragonal scheelite‐related crystal structures have been established by means of single crystal X‐Ray diffraction. Structural motif of KPr(MoO 4 ) 2 has been established for the first time, while KCe(MoO 4 ) 2 has been reinvestigated and its crystal structure data have been refined.

The isolated tetrahedral anion Scheelite structure has showed the advantage of conducting oxygen interstitials but oxygen vacancies can hardly be introduced into Scheelite …

In this work we report high-pressure (HP) and high-temperature (HT) ex situ and in situ experiments in BaWO 4.Starting from powder samples of BaWO 4, scheelite structure (I 4 1 / a), we reached conditions of 2.5–5.5 GPa and 400–1100 K using a Paris-Edinburgh press.The quenched samples were characterized by x-ray diffraction and Raman measurements at ambient conditions.

Figure 1 (Color online) The zircon-type crystal structure of YVO 4 at ambient conditions [left, space group (SG) No. 141, I41/amd, Z = 4] and the high pressure scheelite-type structure [right, SG no. 88, I41/a, Z = 4].The top part of the figure shows corresponding projections along the c axes. For positional parameters see Table .

Effects of zirconium (Zr) doping into BiVO 4 powder on its structural properties and photocatalytic activity for O 2 evolution were examined. The formation of BiVO 4 powder crystallized in a monoclinic scheelite structure (ms-BiVO 4) was achieved when the sample was doped with a relatively small amount of Zr.The photocatalytic activity of Zr-doped ms-BiVO 4 powder was much higher than that of ...

Scheelite Crystallography: Axial Ratios: a:c = 1:2.1694 : Cell Dimensions: a = 5.242, c = 11.372, Z = 4; V = 312.49 Den(Calc)= 6.12 : Crystal System:

Structural stability of scheelite catalysts in the reduction-oxidation cycle. Chemistry Letters, 1984. Kiyoshi Asakawa. Wataru Ueda. Download PDF. Download Full PDF Package. This paper. A short summary of this paper. 37 Full PDFs related to this paper.

Cite this article: XUE Ya-Li,ZHAO Dan,CUI Xiao-Qi, et al. Crystal Structure of Scheelite-type LiTb(WO 4) 2 and Multi-color Emitting Properties Doped by Eu 3+ [J]. CHINESE JOURNAL OF STRUCTURAL CHEMISTRY, 2020, 39(2): 310-320.

Compared with interstitial defects, vacancy-mediated oxide-ion conduction in tetrahedra-based structures is more difficult and occurs rarely. The isolated tetrahedral anion Scheelite structure has showed the advantage of conducting oxygen interstitials but oxygen vacancies can hardly be introduced into Scheelite to promote the oxide ion migration.

like incommensurately modulated structure (3+1)D KNd[MoO 4] 2. The concept has been applied for the description and derivation of scheelite-like compounds differing widely in chemical composition

instabilities of the scheelite structure. In particular, a possible transformation between two different scheelite polytypes with different setting angles has been recently proposed [8] based on the assumption that the LiF 4 tetrahedra remain undis-torted but rotate under pressure, as suggested by Sen et al. [9].

Design of a solid solution with tunable functionality is an attractive strategy toward realizing novel devices with multi-functionalities. In this work, a series of Ca 1−x Cd x WO 4 solid solutions in the entire range 0 ≤ x ≤ 1 with tetragonal scheelite structure have …

Scheelite is an important ore of tungsten which is a strategically important metal. Scheelite is named for the discoverer of tungsten, K. W. Scheele. Although most of the world wide production of tungsten comes from the mineral wolframite, scheelite is especially abundant in the US and provides the United States with most of its supply.

The scheelite crystal structure is characterized by the te-tragonal space group I41 /a or C4h 6 ~listed as No. 88 in the Ref. 7!. In this structure, the primitive unit cell has two ABO4 units ~where A5Ca or Pb and B5Mo or W!. The A and B sites have S4 point symmetry, and the crystal has an

A novel electrolyte based on Gd doped CaMoO 4 with scheelite structure has been investigated. X-ray diffraction results show that the single-phase scheelite structure can be formed at 900 °C.Electrochemical measurement results indicate that the addition of certain quantity Gd 2 O 3 (x = 0.5) can increase the conductivity of CaMoO 4 obviously. The total conductivity of Ca 0.5 Gd 0.5 MoO …

The investigated bismuth vanadate, BiVO4, bismuth vanadomolybdate, Bi0.85V0.55Mo0.45O4, and pure bismuth molybdate, Bi2Mo3O12, oxides prepared by novel spray drying technique having the scheelite structure were found to be monoclinic in the case of BiVO4 and Bi2Mo3O12, whereas Bi0.85V0.55Mo0.45O4 is body-centered tetragonal. The distribution of …

Micro-Pulling-Down Growth And Characterization Of Several Single-Crystal Fibers With Scheelite Structure: Posted on: Degree:Doctor Type:Dissertation Country:China Candidate:J Shu Full Text:PDF GTID:55036 Subject:Condensed matter physics Abstract/Summary:

Design of a solid solution with tunable functionality is an attractive strategy toward realizing novel devices with multi-functionalities. In this work, a series of Ca 1−x Cd x WO 4 solid solutions in the entire range 0 ≤ x ≤ 1 with tetragonal scheelite structure have been successfully prepared for the first time. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and Fourier ...

Structure and electrical conductivity of multicomponent metal oxides having scheelite structure. Download. Related Papers. R.J.Electrochemistry2009.pdf. By Matej Jergel. Study of electrical conductivity and phase transition in Bi2O3–V2O5 system. By Niyazi Al-Areqi.

The phase transformation is irreversible at 300 K, and ZrSiOo (scheelite structure) is quenchable to ambient pressure. X-ray diffraction analysis of ZrSiOo (scheelite structure) yields lattice parameters of a : 0.4726(12) nm and c : 1.0515(44) nm, in excellent agreement with those of ZrSiOo (scheelite structure) formed under simultaneous high-

physical properties, scheelite structure, single crystal, x-ray back-reflection. 1. Introduction A large number of phases having the scheelite struc-ture are known [I].1 The ability of these crystals to accept trivalent ions into solid solution and their opti-cal suitability as laser ion hosts [2] has stimulated

BiVO 4 powder with scheelite structure was obtained by hydrolyzing a nitric acid solution of Bi(NO 3) 3 and Na 3 VO 4 with bases (Na 2 CO 3 and NaHCO 3) at room temperature.Tetragonal BiVO 4 of a high-temperature form was obtained after 4.5 h of preparation time while monoclinic BiVO 4 was done after 46 h. Although the structure and the band gap of tetragonal BiVO 4 with scheelite structure ...

Potassium neodymium molybdenum oxide, KNd(MoO4)2, has been synthesized by the solid-state method. The structure and microstructure have been studied by X-ray powder diffraction and transmission electron microscopy (TEM). TEM revealed that the KNd(MoO4)2 structure is incommensurately modulated. The scheelite-like structure of KNd(MoO4)2 has been refined from X …

The mineral CaWO 4 (scheelite) is well known [ 97] for its optical properties and used in scintillation counters, lasers and optical fibers. The monoclinic ZnWO 4 mineral is known as sanmartinite. Yoon et al. [ 98] reported that the structure changed from wolframite to scheelite with increasing size of …

The scheelite structure of the space group I4{sub 1}/a is adopted for compounds containing large lanthanides Ln=La-Gd. For smaller lanthanides (Ln=Dy-Lu and Y) the wolframite structure with the space group P2/n is observed. In LiTbW{sub 2}O{sub 8}, both structures occur. The phase transition between the two is a slow process making the ...

Tetrahedral units can transport oxide anions via interstitial or vacancy defects owing to their great deformation and rotation flexibility. Compared with interstitial defects, vacancy-mediated oxide-ion conduction in tetrahedra-based structures is more difficult and occurs rarely. The isolated tetrahedral anion Scheelite structure has showed the advantage of conducting oxygen interstitials but ...

Fullprof software was used to analyze XRD data in the Rietveld method which showed a tetragonal scheelite structure in the I4 1 /a space group. The unit cell parameter increases with Ba …

structure (Grasser et al., 1982). The effect on lumines-cence of the addition of small amounts of Mo to scheelite has been investigated by Cannon and Murata (1944), Kroger (1948), Kononov (1967), and Shoji and Sasaki (1978). These studies noted that the fluorescent color of scheelite changes from its characteristic blue to yellow

However, the structure of Pb-BHA complexes adsorbed on the scheelite surface remained unclear. Previous studies have shown that the different molar ratio of Pb/BHA will influence the flotation performance of Pb-BHA complexes collector ( Han et al., 2017a ), indicating the structure of complexes will influence their industrial applications.