scholarly journals Relationships between the Structural, Vibrational, and Optical Properties of Microporous Cancrinite

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 280
Author(s):  
Roman Shendrik ◽  
Ekaterina Kaneva ◽  
Tatiana Radomskaya ◽  
Igor Sharygin ◽  
Alexander Marfin
Keyword(s):  
Optical Properties ◽  
Structural Features ◽  
Resonance Spectroscopy ◽  
Ir Absorption ◽  
Blue Color ◽  
Fold Axis ◽  
Visible Absorption ◽  
X Ray ◽  
Cell Parameters ◽  
Cation Sites

The crystal-chemical, vibrational, and optical properties of microporous aluminosilicate cancrinite have been investigated by combining electron probe microanalysis, single-crystal X-ray diffraction, infrared (IR) absorption, Raman, UV-Visible absorption, and electron spin resonance spectroscopy. The behavior of the peaks in the IR spectra was also studied during the dehydration of the sample. The analyzed sample has the following unit cell parameters (P63): a = 12.63189(14) Å, c = 5.13601(7) Å. The empirical formula, based on 12(Si + Al), is Na6.47Ca1.23K0.01[Al5.97Si6.03O24] (CO3)1.45(SO4)0.03Cl0.01·2H2O. The Al-Si framework of AB-type is formed by columns of based-shared “cancrinite” (CAN) cages, containing Na and H2O positions located on the 3-fold axis, and channels with CO3 groups, lying in two mutually exclusive and partially occupied positions in the center of the channel, and split Na/Ca cation sites. The revealed characteristics are somewhat different in comparison with the cancrinite structural features previously described in the literature. Studied crystals change color from grayish-pink to blue after X-ray irradiation (104 Gy). The blue color of the irradiated cancrinite is caused by the formation (CO3)−● radicals in the crystals. Combining the results obtained using the selected methods will provide a better understanding of the relationships between the structural, chemical, and optical-physical properties of microporous aluminosilicates.

Syntheses and crystal structures of guanidine hydrochlorides with two Schiff base functions as efficient colorimetric and selective sensors for fluoride

2018 ◽  
Vol 73 (8) ◽  
pp. 601-609 ◽  
Author(s):  
Bei Wang ◽  
Pei-Zhi Zhang ◽  
Xin Chen ◽  
Ai-Quan Jia ◽  
Qian-Feng Zhang
Keyword(s):  
Optical Properties ◽  
Schiff Base ◽  
Molecular Structures ◽  
X Ray Diffraction ◽  
Guanidinium Chloride ◽  
Visible Absorption ◽  
X Ray ◽  
Color Changes ◽  
Base Functions ◽  
Magnetic Resonances

AbstractA series of guanidinium chloride derivatives have been synthesized by condensation of 1,3-diaminoguanidine monohydrochloride with heteroaromatic formaldehydes in good yields. All compounds were characterized by nuclear magnetic resonances and infrared spectroscopies, and the molecular structures of four compounds were determined by single crystal X-ray diffraction. The optical properties of these guanidinium chloride derivatives with fluoride anions were investigated, showing selective color changes from colorless to yellow or orange, red-shifted in the ultraviolet/visible absorption spectra.

scholarly journals Bi3+ and Eu3+ Activated Luminescent Behaviors in Non-Stoichiometric LaO0.65F1.7 Structure

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2326
Author(s):  
Sungjun Yang ◽  
Sangmoon Park
Keyword(s):  
Optical Materials ◽  
Emission Spectra ◽  
Lattice Energy ◽  
Host Lattice ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Diffraction Patterns ◽  
Cation Sites

Optical materials composed of La1-p-qBipEuqO0.65F1.7 (p = 0.001–0.05, q = 0–0.1) were prepared via a solid-state reaction using La(Bi,Eu)2O3 and NH4F precursors at 1050 °C for two hours. X-ray diffraction patterns of the phosphors were obtained permitting the calculation of unit-cell parameters. The two La3+ cation sites were clearly distinguished by exploiting the photoluminescence excitation and emission spectra through Bi3+ and Eu3+ transitions in the non-stoichiometric host lattice. Energy transfer from Bi3+ to Eu3+ upon excitation with 286 nm radiation and its mechanism in the Bi3+- and Eu3+-doped host structures is discussed. The desired Commission Internationale de l’Eclairage values, including emissions in blue-green, white, and red wavelength regions, were obtained from the Bi3+- and Eu3+-doped LaO0.65F1.7 phosphors.

Design and Optical Properties of Rare Earth-Based Mixed-Anions (O, S, F) Compounds

2002 ◽  
Vol 755 ◽  
Author(s):  
Damien Pauwels ◽  
Alain Demourgues ◽  
Alain Tressaud
Keyword(s):  
Optical Properties ◽  
Rare Earth ◽  
Solid State ◽  
Visible Absorption ◽  
X Ray ◽  
Solid State Route ◽  
Earth Environment ◽  
Fluorite Type ◽  
Uv Visible ◽  
Single Crystal Analysis

ABSTRACTRare earth-based mixed-anions (O, S, F) compounds have been prepared by solid state route. The structures have been determined on the basis of powder diffraction (X-ray/neutrons) refinement and/or single crystal analysis. They have been described as a stacking of [Sx] 2x- layers and fluorite type blocks. The evaluation of the rare earth environment (bondlength, number of neighbors) can be directly related to the bandgap and to the UV-visible absorption in the La-based compounds.

scholarly journals Lead-antimony sulfosalts from Tuscany (Italy). XVIII. New data on the crystal-chemistry of boscardinite

2017 ◽  
Vol 81 (1) ◽  
pp. 47-60 ◽  
Author(s):  
Cristian Biagioni ◽  
Yves Moëlo
Keyword(s):  
Single Crystal ◽  
Diffraction Study ◽  
Type Specimen ◽  
Structural Features ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Mineral Associations ◽  
Crystal Chemical Data ◽  
New Findings

AbstractBoscardinite, ideally TlPb4(Sb7As2)∑9S18, has been described recently as a new homeotypic derivative of baumhauerite, found at Monte Arsiccio mine, Apuan Alps, Tuscany, Italy. New findings of boscardinite in different mineral associations of this deposit have allowed the collection of new crystal-chemical data. Electron-microprobe analysis of the crystal used for the single-crystal X-ray diffraction study gave (in wt.%): Ag 1.81(5), Tl 12.60(21), Pb 17.99(12), Hg 0.14(5), As 9.36(12), Sb 33.60(27), S 23.41(30),Cl 0.06(1), total 98.97(100). On the basis of ∑Me= 14 apfu, it corresponds to Ag0.42Tl1.52Pb2.14Hg0.02(Sb6.82As3.08)∑9.90S18.04Cl0.04. With respect to the type specimen, these new findings are characterized by a strong Pb depletion, coupled with higher Tl contents, and a significant As enrichment. The single-crystal X-ray diffraction study of this (Tl,As)-enriched boscardinite confirms the structural features described for the type sample. The unit-cell parameters area= 8.1017(4),b= 8.6597(4),c= 22.5574(10) Å, α = 90.666(2), β = 97.242(2), γ = 90.850(2)°,V= 1569.63(12) Å3, space groupP̄1. The crystal structure was refined down toR1= 0.0285 on the basis of 6582 reflections withFo> 4σ(Fo). Arsenic is dominant in threeMeS3sites, compared to one in type boscardinite. The main As-enrichment is observed in the sartorite-type sub-layer. Owing to this chemical peculiarity, (Tl, As)-rich boscardinite shows alternation, alongb, of Sb-rich sites and As-rich sites; this feature represents the main factor controlling the 8 Å superstructure. The chemical variability of boscardinite is discussed; the Ag increase observed here gets closer to stoichiometric AgTl3Pb4(Sb14As6)∑20S36(Z= 1), against possible extension up to AgTl2Pb6(Sb15As4)∑19S36for type boscardinite.

Ag2S/ZnS nanocomposites: Synthesis, structure and optical properties

2020 ◽  
pp. 2150033
Author(s):  
M. A. Ramazanov ◽  
S. G. Nuriyeva ◽  
H. A. Shirinova ◽  
A. H. Karimova ◽  
M. A. Nuriyev
Keyword(s):  
Optical Properties ◽  
Structural Investigation ◽  
Emission Spectra ◽  
Structural Features ◽  
Core Shell ◽  
Zns Nanoparticles ◽  
Sem Images ◽  
X Ray ◽  
The Core ◽  
Novel Method

Ag2S/ZnS nanocomposites were synthesized using a novel method, and their structural features and optical properties were also investigated. For the structural investigation of the core/shell-like nanocomposites, X-ray powder diffraction technique (XRD) and scanning electron microscopy (SEM) were used. Optical features of Ag2S/ZnS nanocomposites were studied by UV-Vis absorption and photoluminescence spectroscopy (PL). According to the SEM images, the sizes of the Ag2S, ZnS nanoparticles and Ag2S/ZnS core/shell-like nanocomposites are in the region of the 10–15; 25–50 and 15–80 nm, respectively. Furthermore, the absorption spectroscopy indicates that the bandgap of Ag2S/ZnS nanocomposites is approximately 2.4 eV. By comparison of the intensities of the emission spectra, it was clear that the intensity of Ag2S/ZnS is much lower than that of ZnS.

Crystal chemistry and nomenclature of fillowite-type phosphates

2021 ◽  
Vol 59 (4) ◽  
pp. 781-796
Author(s):  
Frédéric Hatert ◽  
Edward S. Grew ◽  
Pietro Vignola ◽  
Nicola Rotiroti ◽  
Fabrizio Nestola ◽  
...  
Keyword(s):  
Diffraction Data ◽  
Divalent Cations ◽  
Complex Structure ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Cation Sites ◽  
Cation Distributions

ABSTRACT The crystal chemistries of five samples of minerals belonging to the fillowite group were structurally investigated: (A) fillowite from the Buranga pegmatite, Rwanda; (B) fillowite from the Kabira pegmatite, Uganda; (C) johnsomervilleite from Loch Quoich, Scotland; (D) johnsomervilleite from the Malpensata pegmatite, Italy; and (E) chladniite from the Sapucaia pegmatite, Minas Gerais, Brazil. Their crystal structures were refined in space group R (No. 148), using single-crystal X-ray diffraction data, to R1 values of (A) 3.79%, (B) 3.52%, (C) 4.14%, (D) 4.04%, and (E) 5.59%. Unit-cell parameters are: (A) a = 15.122(1), c = 43.258(4) Å; (B) a = 15.125(1), c = 43.198(3) Å; (C) a = 15.036(2), c = 42.972(9) Å; (D) a = 15.090(2), c = 43.050(9) Å; and (E) a = 15.1416(6), c = 43.123(2) Å. The asymmetric unit contains 15 cation sites with coordinations ranging from V to IX, as well as six P sites. The complex structure can be split into three types of chains running parallel to the c axis. These chains are composed of edge- and face-sharing polyhedra. Detailed cation distributions were determined for all five samples, and their comparison allowed us to establish the general formula A3BC11(PO4)9 for fillowite-type phosphates, where A represents the group of sites mainly occupied by Na, B the Ca sites, and C the sites containing the divalent cations Fe2+, Mn, and Mg. This formula was accepted by the CNMNC, and the four valid mineral species occurring in the fillowite group are fillowite (C = Mn), johnsomervilleite (C = Fe2+), chladniite (C = Mg), and galileiite (B and C = Fe2+). Stornesite-(Y) is discredited, since this mineral corresponds to Y-bearing chladniite.

Influence of Organic Polymers as Capping Agent on Structural and Optical Properties of ZnS:Mn2+ and CdS Nanocrystals

2008 ◽  
Vol 8 (1) ◽  
pp. 301-308 ◽  
Author(s):  
Ashish K. Keshari ◽  
M. Kumar ◽  
Prashant K. Singh ◽  
Avinash C. Pandey
Keyword(s):  
Optical Properties ◽  
Photo Luminescence ◽  
Organic Polymers ◽  
Visible Absorption ◽  
Capping Agents ◽  
X Ray ◽  
Cds Nanocrystals ◽  
Uv Visible ◽  
Organic Capping ◽  
Co Precipitation

We have synthesized the luminescent ZnS:Mn2+ and bare CdS nanocrystals by employing polyvinyl alcohol (PVA), citric acid (CA) and biotin as organic capping agents by chemical co-precipitation route. The synthesized materials were characterized by X-ray diffraction, small angle X-ray scattering and transmission electron microscopy for the structural analysis, while UV-Visible spectroscopy and photoluminescence (PL) for optical properties. The results show that all the three organic polymers have the same effect and are capable of controlling the growth of the nanoclusters. From UV-Visible absorption spectra, it was observed that different capping agents do not affect the band gap of ZnS:Mn2+ system as well, while capping effect clearly observed on PL properties of ZnS:Mn2+ system. We have observed a novel result that capping with biotin show excellent photo-luminescence as compared to capping of PVA and CA on ZnS:Mn2+-systems. On the other hand, the annealing of these systems leads to degradation of luminescence intensity.

Powder Diffraction Data for ZnGa2S4

1990 ◽  
Vol 5 (4) ◽  
pp. 223-224 ◽  
Author(s):  
Charlotte K. Lowe-Ma
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Tetragonal Unit Cell ◽  
Group I ◽  
Cation Sites

AbstractObserved and calculated X-ray powder diffraction data are reported for ZnGa2S4. After corrections to the observed data, refined tetragonal unit cell parameters ao= 5.2779(2), co= 10.4179(8) Å (λ = 1.54051 Å) were obtained. The powder pattern for ZnGa2S4was calculated in space group Iwith a stoichiometric amount of Zn and Ga randomly distributed amongst the two cation sites.

Structure of Pb-rich chabournéite from Jas Roux, France

2015 ◽  
Vol 71 (1) ◽  
pp. 81-88 ◽  
Author(s):  
Cristian Biagioni ◽  
Yves Moëlo ◽  
Georges Favreau ◽  
Vincent Bourgoin ◽  
Jean-Claude Boulliard
Keyword(s):  
Crystal Structure ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Structural Formula ◽  
Unit Cell ◽  
Single Crystal Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Cation Sites ◽  
Pyramidal Groups

The crystal structure of a specimen of `Pb-rich' chabournéite from Jas Roux, Hautes-Alpes, France, with the chemical formula obtained by electron microprobe analysis of Ag0.04 (1)Tl2.15 (2)Pb0.64 (1)Sb5.12 (1)As5.05 (1)S17.32 (5), has been solved by X-ray single-crystal diffraction on the basis of 36 550 observed reflections (withFo> 4σFo) with a finalR1= 0.074. Pb-rich chabournéite is triclinicP1, with unit-cell parametersa= 8.5197 (4),b= 42.461 (2),c= 16.293 (8) Å, α = 83.351 (2), β = 90.958 (2), γ = 84.275 (2)°,V= 5823 (3) Å3. Its structural formula is close to [Tl2(Pb0.8Tl0.1Sb1.1)](Sb4.1As4.9)S17, withZ= 8. Its crystal structure is formed by the alternation of two pairs of slabs along thebaxis, deriving from the SnS and PbS archetypes, respectively. 104 independent cation sites and 136 S sites occur in the unit cell. Slab interfaces show the alternation, alongc, of Tl sites, ninefold coordinated, with Pb, Sb or mixed/split (Pb,Sb) and (Pb,Tl) sites. Within the slabs, 72 independentM3+sites (M3+= As, Sb) occur. ConsideringM3+—S bond distances shorter than 2.70 Å,MS3triangular pyramidal groups are condensed according to variousMmSnchain fragments (`polymers'). The solution of the crystal structure of chabournéite allows its comparison with the closely related homeotypes protochabournéite and dalnegroite.

Crystal chemistry and binding of NO2, SCN and SeCN to Co in cobalamins

2003 ◽  
Vol 59 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Gianpiero Garau ◽  
Silvano Geremia ◽  
Luigi G. Marzilli ◽  
Giorgio Nardin ◽  
Lucio Randaccio ◽  
...  
Keyword(s):  
Nitro Group ◽  
Crystal Chemistry ◽  
Structural Features ◽  
Close Packing ◽  
Synchrotron Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Coordination Isomers ◽  
Equatorial Ligand

Results of the accurate crystal structure determination of NO2Cbl·2LiCl (1), NO2Cbl·NaCl (2), NCSCbl (3) and NCSeCbl (4), based on synchrotron diffraction data collected at 100 K, are described. The nitro group in (1) was found to be disordered with two orientations that differ by a rotation of ∼60° about the Co—NO2 bond, whereas in (2) the nitro group has only one orientation. The first X-ray structural determination of a cobalamin with a Co—Se bond is reported. Comparison of the axial distances indicates that SeCN has a bond length of 2.384 (3) Å and that the trans influence on the Co—N bond is only slightly greater than that of SCN. The crystals of the thiocyanate cobalamin contain both the S- and N-bonded coordination isomers in a 3:2 ratio. The structural features of the Co—S bond in cobalamins are discussed. The crystal chemistry of cobalamins is discussed in terms of packing of roughly spherical molecules. The unit-cell parameters can be used to group the cobalamins' crystal structures in different arrays intermediate between distorted hexagonal close packing and primitive hexagonal arrangements. The structural features of cobalamins, and of cobaloximes that have the same axial fragment as the cobalamins, are reviewed and discussed in terms of the cis influence of the equatorial ligand.

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