CdF2 Research Articles

A thorough investigation of HTL layers to develop and simulate AgCdF3-based perovskite solar cells

Perovskite photocells are gaining attention mainly because of their special features. The purpose of this work is to use the SCAPS-1D simulator to model the action of absorbers in perovskite photocells that are based on silver cadmium fluoride. This research investigates how varying HTLs (Cu2O and P3HT) combined with an In2S3 ETL influence the efficiency of these solar cells. The PCEs are 30.33 and 30.02 %, with VOC of 0.91 and 0.90 V, JSC of 42.00 and 41.88 mAcm−2, and FF of 79.45 and 79.59 % for Cu2O and P3HT HTLs, respectively. After optimizing the device (Al/FTO/In2S3/AgCdF3/Cu2O/Ni), this study also looks at how the optimized thickness of ETL and HTL, acceptor density, donor and defect density, temperature, J-V and QE properties, generation and recombination rates, series, and shunt resistance impact performance. This comprehensive simulation research enables scientists to create cost-efficient and highly effective PSCs, furthering advancements in solar technology.

Luminescence properties of CdF2 single crystals co-doped with Er3+ and Y3+ ions.

The luminescence properties of erbium and yttrium co-doped cadmium difluoride with three different concentrations of yttrium were investigated. First, we synthesized single crystal samples with good optical quality using the Bridgman technique. From the optical absorption spectra, recorded at room temperature, both in the ultraviolet-visible and infrared spectral ranges, Judd-Ofelt analysis was performed based on yttrium concentrations to predict the radiative properties of Er3+ luminescent ions. For the 10% optimum concentration of yttrium, a detailed photoluminescence investigation was carried out. We mainly explored green, red, and near-infrared fluorescence under different excitation wavelengths and presented their highlight spectroscopic characteristics. The desired transitions had relatively high emission cross-sections both under visible and near-infrared excitation. Optical gain followed a similar trend. Furthermore, the dynamic fluorescence study showed a significant increase in the measured lifetime under an 800 nm infrared excitation. The upconversion process under an 800 nm excitation produced quantum efficiency greater than 100% due to the contribution of more than one energy transfer mechanism.

Design and simulation of a highly sensitive one-dimensional photonic crystal for different chemical sensing applications

The main goal of this study is to construct a highly sensitive one-dimensional (1D) photonic crystal sensing system for chemical detection. Magnesium fluoride and cadmium fluoride, tantalum pentoxide and silicon dioxide, titanium dioxide and silicon dioxide, and zinc sulphide and silicon dioxide are the four different layer materials that have been taken into consideration. Defect layer width ranges from 3500 nm to 5000 nm. Every combination of layers that was taken into consideration exhibited sensitivity that was greater than 500 nm/RIU, according to the simulation results. In that combination of layers, silicon dioxide and titanium dioxide have shown the highest sensitivity of 675 nm/RIU. Defects wider than 4000 nm can achieve 98 % transmission efficiency. The sensor displayed a Figure of Merit (FoM) of 8437, a limit of detection (LOD) of 7.30 ×10-6 RIU, and a maximum quality factor of 13,687.

Production of acetone by catalytic hydration of acetylene

Among the known processes for the production of acetone, the most promising is the synthesis by hydration of acetylene in the presence of catalysts. The advantage of this method is the possibility of carrying out the process in existing acetaldehyde production plants. On the other hand, the process of simultaneous production of acetaldehyde and acetone under the action of polyfunctional catalysts and the implementation of the process using flexible technology is promising. To study the influence of various factors on the process of obtaining acetone by the catalytic hydration of acetylene and to create a technology for producing acetone. The specific surface area, crushing strength, total pore volume, and ash content of the samples were determined. Acetylene was saturated with water at a temperature of 70-80 ℃ and a ratio of water: and acetylene = (1:3)-(1:5), mol was passed through the catalyst bed at 360 ℃ with a space velocity of 180-200h-1. The gas-vapour mixture leaving the reactor was cooled in a refrigerator. The reaction products were collected with water. The catalyst contains acetaldehyde, acetone, crotonaldehyde, etc. To maintain the degree of acetylene conversion not lower than 80%, the reaction temperature was raised by 10 ℃ every 20 hours. After 96-120 hours, the degree of acetylene conversion decreases to 75-70%. The reactions of catalytic hydration of acetylene to acetaldehyde and acetone were carried out on the selection of polyfunctional mixed catalysts. As a result, a catalyst with cadmium fluoride and chromium(III) oxide dissolved in alumina promoted with aluminium fluoride was chosen to produce acetaldehyde. Acetaldehyde is formed by the interaction of acetylene: water =1:3–1:5 at 360-440 ℃ in the presence of a catalyst based on cadmium fluoride with a composition of 18% CdF2, 2,0% AlF3, 5% Cr2O3, 75% Al2O3. The addition of zinc oxide or fluoride to the cadmium-chromium-aluminium catalyst (Catalysts No.5) ensures the selectivity of the catalyst and directs the acetylene hydration reaction towards the formation of acetone. As the temperature rises above 450 ℃, the yield of acetone formation and the selectivity of the process decrease due to the transformation of the formed acetone into other substances. In the temperature range of 360-500 ℃, the relationship between the reaction yield and temperature is extreme, and at 450 ℃ the yield was considered to be maximum. Based on the obtained results, a technological scheme for the production of acetone by the catalytic hydration of acetylene was proposed.

DEVELOPMENT AND INVESTIGATION OF PROPERTIES OF MIXED CATALYSTS FOR VAPOR-PHASE HYDRATION OF ACETYLENE

In order to develop new catalysts for the synthesis of acetaldehyde by vapor-phase hydration of acetylene, new mono- and bifunctional catalysts based on cadmium, zinc, chromium, and iron compounds on supports were developed and their most important textural characteristics were studied. It was shown that zinc oxide and cadmium fluoride are bifunctional catalysts, in the presence of which acetaldehyde was synthesized with a yield of 69.0 — 70.0%. It has been established that the stability of their operation before regeneration exceeds more than 100 hours, i.e. 1.3 times more than industrial cadmium-calcium phosphate catalyst.

Interactions of Cadmium Fluoride with Other Fluorides

Interactions of Cadmium Fluoride with Other Fluorides

Structural Disorder and Heat Capacity of a Solid Solution between Cadmium and Strontium Fluorides

The heat capacity Cp(T) of cadmium fluoride, strontium fluoride, and the Cd0.5Sr0.5F2 solid solution has been studied experimentally (2–300 K). We have detected deviations ΔCp(T) of the Cp(T) data from additivity. The low-temperature (2–50 K), positive deviations ΔCp(T) have been tentatively attributed to the effect of two-level systems associated with the glasslike character of the low-temperature thermal properties of the solution due to disorder in the Cd–Sr sublattice. The high-temperature (100–300 K), negative deviations ΔCp(T) are caused by the effect of anharmonicity of lattice vibrations, whose increasing role is also associated with the disordered arrangement of atoms in the crystal lattice upon formation of the solution. The Cp(T) data for the solution of the system studied have been analyzed in the Debye–Einstein model. We have determined model parameters: characteristic temperatures Θi and the fractions of different contributions, ai, to total thermal characteristics of the substances studied.

Photodegradation of Rhodamine B using Cd-Al/C double layered hydroxide catalyst

This paper presents the degradation of Rhodamine B using cadmium aluminium carbon (Cd-Al/C) catalyst under visible light. The layered double hydroxide was successfully prepared from cadmium fluoride (CdF2), aluminium chloride (AlCl3), and rice husks activated carbon, and then characterized by X-ray Diffaraction (XRD) Scaning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) methods. The peaks at 2Ө 23.4 and 35.5 in the XRD result confirmed the presences of LDH. The effect of contact time, catalyst dosage, pH and initial concentration, on the photo degradiation of Rhodamine B were investigated. The experimental results showed that after 100min visible light irradiation, the percentage degradation using 200mg Cd-Al/C, pH 7 and 3ppm Rhodamine B concentration reached to 76.22%. For kinetics studies the data obtained were analysed using pseudo first order and pseudo second order kinetic models. From the linear regression coefficient values the data were found to be best fitted to pseudo second order kinetics. The results revealed that the Cd-Al/C show good catalytic activity.
 Key words: Layered Double Hydroxide (LDH) Cadnium fluoride, Aluminium Chloride and Rhodamine B.

Composite vibrational spectroscopy of the group 12 difluorides: ZnF2, CdF2, and HgF2.

The vibrational spectra of group 12 difluorides, MF2 (M = Zn, Cd, Hg), were investigated via coupled cluster singles, doubles, and perturbative triples, CCSD(T), including core correlation, with a series of correlation consistent basis sets ranging in size from triple-zeta through quintuple-zeta quality, which were then extrapolated to the complete basis set (CBS) limit using a variety of extrapolation procedures. The explicitly correlated coupled cluster method, CCSD(T)-F12b, was employed as well. Although exhibiting quite different convergence behavior, the F12b method yielded the CBS limit estimates closely matching more computationally expensive conventional CBS extrapolations. The convergence with respect to basis set size was examined for the contributions entering into composite vibrational spectroscopy, including those from higher-order correlation accounted for through the CCSDT(Q) level of theory, second-order spin-orbit coupling effects assessed within four-component and two-component relativistic formalisms, and vibrational anharmonicity evaluated via a perturbative treatment. Overall, the composite results are in excellent agreement with available experimental values, except for the CdF2 bond-stretching frequencies compared to spectral assignments proposed in a matrix isolation infrared and Raman study of cadmium difluoride vapor species [Loewenschuss et al., J. Chem. Phys. 50, 2502 (1969); Givan and Loewenschuss, J. Chem. Phys. 72, 3809 (1980)]. These assignments are called into question in the light of the composite results.

Quercetin protects mice kidney collagen against the damage induced by cadmium fluoride

Cadmium fluoride (CdF) is a well known environmental toxin. In the present study protective effect of quercetin against CdF induced changes in renal hydroxyproline (Hyp) fractions and collagen was investigated. Five experimental groups were studied viz., Group 1—normal (control) mice; Group 2—mice administered single intraperitoneal (ip) injection of CdF2 at a dose of 2 mg/kg body weight (bw) and sacrificed after 24 h; Group 3—mice administered single ip injection of CdF at a dose of 2 mg/kg bw but sacrificed after 48 h; Group 4—mice injected with quercetin alone at a dose of 100 mg quercetin/kg bw ip and Group 5—mice injected ip with 100 mg quercetin/kg bw followed by 2 mg CdF2/kg bw after 2 h. Mice in Groups 4 and 5 were sacrificed 24 h after the last treatment. 2 mg/kg bw CdF caused a significant decrease in free and protein bound Hyp fractions after 24 h. However after 48 h, significant decreases were observed in all the renal Hyp fractions viz., free, peptide bound, protein bound and total Hyp fractions. There was also a significant decrease in total renal collagen after 48 h of CdF treatment. Quercetin pretreatment followed by CdF injection restored the altered parameters to near normal levels. The authors conclude that quercetin may protect the kidney collagen against CdF assault.

Protective effects of quercetin on cadmium fluoride induced oxidative stress at different intervals of time in mouse liver.

Quercetin, a member of the flavonoid family is a major antioxidant acquired in humans by food consumption, while Cadmium fluoride (CdF2) is one of the naturally occurring chemicals having adverse effects. The protective effect of quercetin on time dependent oxidative damage induced in mice liver by CdF2 was studied in the following groups of mice consisting of six mice each: (i) control group; (ii) mice treated with single i.p injection of 2 mg/kg bw CdF2 for 24 h; (iii) mice treated with single i.p injection of 2 mg/kg bw CdF2 for 48 h; (iv) mice treated with single i.p injection of quercetin (100 mg/kg bw); (v) mice treated with i.p injection of 100 mg/kg bw of quercetin followed by i.p injection of CdF2 (2 mg/kg bw) for 24 h; and (vi) mice treated with i.p injection of 100mg/kg bw of quercetin followed by CdF2 (2 mg/kg bw) for 48 h. Administration of quercetin two hours before CdF2 significantly reduced the biochemical alterations in reduced glutathione, ascorbic acid, lipid peroxidation, super oxide dismutase, catalase and total protein (p<0.05). Histopathology also showed the protective effect of quercetin. The livers treated with CdF2 were atrophic, markedly nodular, inflamed and necrotic. However, this effect was reduced to a minimum in the mice pre-treated for two hours with quercetin.

Influence of lead and cadmium fluoride variation on white light emission characteristics in oxyfluoride glasses and glass–ceramics

The radiative properties of Dy-doped glasses and glass–ceramic phosphors with varying lead and cadmium fluoride content are investigated in the present study for white light emitting applications. The precipitation of cubic lead fluoride phase of 10–18nm crystallites was determined with the help of x-ray diffraction studies and the nanocrystalline nature was confirmed with scanning electron microscopy studies. The small size of the nanocrystallites enables the fabrication of transparent glass–ceramics which is verified by UV–vis spectroscopic study. The photoluminescence and lifetime measurements indicate towards progressive changes in the Dy3+ ion surroundings and propose enhanced energy transfers taking place post-heat treatments. Finally, CIE chromaticity coordinates are found to lie in the white region proposing the suitability of the present studied materials for color display devices.

New Ways to Obtain Monofocons from Quartz Glass

Amethod of obtaining monofocons from quartz glass based on the interaction of the glass with fluoride melts and solutions, specifically, cadmium fluoride melt and solutions of hydrofluoric acid, has been developed. The theoretical underpinnings for diverse variants of a method of producing monofocons from quartz-glass are examined.

On the influence of lead and cadmium fluoride content on thermal, optical and structural properties of oxyfluoride glass

This study reveals the effect of PbF2 and CdF2 addition on the aluminosilicate oxyfluoride glass network over a wide compositional range. The structure of glasses in SiO2–Al2O3–PbF2 and SiO2–Al2O3–PbF2–CdF2 system matrices was studied by using DTA, XRD, UV–VIS, density, Raman and FTIR spectroscopy. The observed shifts of absorption edge due to band gap variations with heavy metal fluoride (HMF) addition are compared with theoretical model of optical basicity and physical parameters derived from density. The variation in Tg, and stability factor are supported by Raman and FTIR results which show formation of NBOs and other super structural units with addition of HMF in the aluminosilicate network.

Luminescence of Cadmium Fluoride Doped with Rare-earth Ions

Absorption, excitation and emission spectra of cadmium fluoride crystals doped with rare-earth ions were investigated. In contrast to alkaline-earth fluorides the absorption spectra due to 4f - 5d transitions of Ce$^{3+}$, Pr$^{3+}$ and Tb$^{3+}$ ions are broadened. No 5d-4f emissions were observed. These prove that 5d(e$_g$) levels of rare earth ions lie in conduction band of CdF$_2$ crystal. Emission spectra of Tb$^{3+}$ show the group of 4f-4f $^5$D$_4$-$^7$F$_j$ lines in contrast to other alkaline-earth fluorides where emission due to $^5$D$_3$-$^7$F$_j$ transitions is also observed. The absence of the emission is due to position of $^5$D$_3$ level within condution band. Among the all measured crystals doped with impurity ions (Pr, Nd, Eu, Ho, Tb, Tm, Yb, Ga, In or Mn), the CdF$_2$ doped with Pr$^{3+}$, Tb$^{3+}$, or Mn$^{2+}$ ions have the highest light outputs under x-ray excitation.

Synthesis and crystal structures of novel LaOAgS-type alkaline earth – Zinc, manganese, and cadmium fluoride pnictides

Systematic studies of the LaOAgS-type compounds among alkaline earth – Zn/Cd/Mn fluoride pnictides revealed the existence of new representatives SrFMnP, SrFMnAs, SrFMnSb, SrFZnAs, SrFZnSb, BaFZnAs, BaFCdP, and BaFCdAs. Similar to rare-earth oxide compounds and contrary to isolobal chalcogenides of Cu/Ag, not all possible compositions could be realized. No compound of the structure type is formed for calcium; strontium forms fluoride pnictides only with zinc and manganese, while for barium, new representatives are also formed with cadmium. This trend, which possibly has a geometrical origin, is corroborated by quantum chemical calculations. Formation of NdOZnP-type compounds also was not observed suggesting the structure to be characteristic only for rare earth – zinc oxide phosphides.

Electronic and optical properties of cadmium fluoride: The role of many-body effects

Electronic excitations and optical spectra of CdF${}_{2}$ are calculated up to ultraviolet employing state-of-the-art techniques based on density functional theory and many-body perturbation theory. The GW scheme proposed by Hedin has been used for the electronic self-energy to calculate single-particle excitation properties as energy bands and densities of states. For optical properties many-body effects, treated within the Bethe-Salpeter equation framework, turn out to be crucial. A bound exciton located about 1 eV below the quasiparticle gap is predicted. Within the present scheme the optical absorption spectra and other optical functions show an excellent agreement with experimental data. Moreover, we tested different schemes to obtain the best agreement with experimental data. Among the several schemes, we suggest a self-consistent quasiparticle energy scheme.

Semiconductor CdF₂:Ga and CdF₂:In Crystals as Media for Real-Time Holography.

Monocrystalline cadmium fluoride is a dielectric solid that can be converted into a semiconductor by doping with donor impurities and subsequent heating in the reduction atmosphere. For two donor elements, Ga and In, the donor (“shallow”) state is a metastable one separated from the ground (“deep”) state by a barrier. Photoinduced deep-to-shallow state transition underlies the photochromism of CdF2:Ga and CdF2:In. Real-time phase holograms are recorded in these crystals capable of following up optical processes in a wide frequency range. The features of photochromic transformations in CdF2:Ga and CdF2:In crystals as well as holographic characteristics of these media are discussed. Exemplary applications of CdF2-based holographic elements are given.

Phase transition of cadmium fluoride under high pressure

We investigated the high pressure phases of CdF 2 by a joint theoretical and experimental study. The structural and electronic properties of CdF 2 were extensively explored to high pressure by ab initio calculations based on the density functional theory. A structural phase transition from the fluorite-type ( Fm-3m, Z = 4 ) structure to the cotunnite-type ( Pnma, Z = 4 ) structure was estimated below 8 GPa, and this phase transition was examined by the high pressure experiments up to 35 GPa at room temperature. Both high pressure angle dispersive X-ray diffraction and Raman spectroscopy experiments provided convincing evidence to verify the phase transition. Our work makes clear pressure-induced phase transitions and structural information of CdF 2 under high pressure.

Formation kinetics of volume holograms in reversible photochromic media

The specific features of recording a volume hologram in a photochromic reversible medium, which is characterized by simultaneous occurrence of hologram recording and relaxation, have been considered by the example of two ion crystals, i.e., cadmium fluoride with bistable gallium centers and calcium fluoride with color centers.