Single compound in-situ synthesis of core-shell CaF2 nanoparticles based broad band antireflective coatings for solar energy conversion

Reddy, K. Chandra Sekhar; Chingakham, Ch.; Gupta, Bikesh; Prasad, M. Shiva; Atchuta, S.R.; Sakthivel, S.

doi:10.1016/j.solener.2019.07.083

Cited by 14 publications

(5 citation statements)

References 31 publications

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“…On the other hand, the deconvolution of the peak O1s revealed the presence of signals that correspond to O 2− (532.7 eV) and OH − (535.4 eV) due to the well-known adsorption of H 2 O molecules on the CaF 2 (111) plane ( Figure 4 C) [ 30 , 36 ]. This fact is also reflected in the high-resolution F1s peak ( Figure 4 B) that displays a very prominent peak centered at 684.9 eV, assigned to F-Ca bonding, in addition to a very weak peak centered at 686.9 eV that is due to F − defects at the surface of CaF 2 , most likely originating from water adsorption [ 28 , 30 , 36 ]. Moreover, the Ca2p peak displayed a doublet owing to the spin-orbit splitting typical of Ca(II) assigned to Ca2p 1/2 and Ca2p 3/2 , centered at 351.4 eV and 348.0 eV, respectively, and with 1:2 area ratio ( Figure 4 D) [ 28 , 30 , 36 , 40 , 41 , 42 , 43 ].…”

Section: Resultsmentioning

confidence: 99%

“…This fact is also reflected in the high-resolution F1s peak ( Figure 4 B) that displays a very prominent peak centered at 684.9 eV, assigned to F-Ca bonding, in addition to a very weak peak centered at 686.9 eV that is due to F − defects at the surface of CaF 2 , most likely originating from water adsorption [ 28 , 30 , 36 ]. Moreover, the Ca2p peak displayed a doublet owing to the spin-orbit splitting typical of Ca(II) assigned to Ca2p 1/2 and Ca2p 3/2 , centered at 351.4 eV and 348.0 eV, respectively, and with 1:2 area ratio ( Figure 4 D) [ 28 , 30 , 36 , 40 , 41 , 42 , 43 ]. Finally, the XPS analysis enabled the estimation of the F:Ca atomic ratio to equal 2.04, highlighting the chemical formula of CaF 2 and corroborating the SEM-EDX findings.…”

Section: Resultsmentioning

confidence: 99%

“…Although the optimum size depends on the targeted bioapplications [ 9 ], the part -CaF 2 generated in this study fell within the range of liposomes and polymeric particles used in drug delivery systems and biomedical imaging [ 9 , 10 ]. Moreover, various methods enabled the size control of the CaF 2 particles to fit a specific application [ 16 , 20 , 24 , 28 ]. Additionally, EDX analysis showed the existence of various chemical elements at different concentrations, including calcium and fluorine ( Figure 1 C).…”

Section: Resultsmentioning

confidence: 99%

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Bimodal Ultrasound and X-ray Bioimaging Properties of Particulate Calcium Fluoride Biomaterial

et al. 2021

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Ultrasound (US) and X-ray imaging are diagnostic methods that are commonly used to image internal body structures. Several organic and inorganic imaging contrast agents are commercially available. However, their synthesis and purification remain challenging, in addition to posing safety issues. Here, we report on the promise of widespread, safe, and easy-to-produce particulate calcium fluoride (part-CaF2) as a bimodal US and X-ray contrast agent. Pure and highly crystalline part-CaF2 is obtained using a cheap commercial product. Scanning electron microscopy (SEM) depicts the morphology of these particles, while energy-dispersive X-ray spectroscopy (EDS) confirms their chemical composition. Diffuse reflectance ultraviolet-visible spectroscopy highlights their insulating behavior. The X-ray diffraction (XRD) pattern reveals that part-CaF2 crystallizes in the face-centered cubic cell lattice. Further analyses regarding peak broadening are performed using the Scherrer and Williamson–Hall (W-H) methods, which pinpoint the small crystallite size and the presence of lattice strain. X-ray photoelectron spectroscopy (XPS) solely exhibits specific peaks related to CaF2, confirming the absence of any contamination. Additionally, in vitro cytotoxicity and in vivo maximum tolerated dose (MTD) tests prove the biocompatibility of part-CaF2. Finally, the results of the US and X-ray imaging tests strongly signal that part-CaF2 could be exploited in bimodal bioimaging applications. These findings may shed a new light on calcium fluoride and the opportunities it offers in biomedical engineering.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Bimodal Ultrasound and X-ray Bioimaging Properties of Particulate Calcium Fluoride Biomaterial

et al. 2021

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“…In another report, Reddy et al fabricated core-shell CaF 2 @CaF 2 nanoparticles (8-40 nm in diameter) by hydrothermal synthesis where the core and shell differ in their crystallographic directions of CaF 2 . [84] To prepare an antireflective film on a glass substrate, the glass was dip-coated in a transparent sol containing the CaF 2 @CaF 2 nanoparticles mixed with CTAB, which acted as capping agent. The purpose of the CTAB capping agent was to increase the porosity of the coated film, which increased the tendency for the incident light to undergo multiple reflections thus enhancing light transmittance.…”

Section: Solar Cellsmentioning

confidence: 99%

Core‐Shell Micro‐ and Nano‐Structures for The Modification of Light‐Surface Interactions

Yeo,

Yu Tan

et al. 2023

Advanced Optical Materials

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Controlling how a material interacts with light is key to optimizing its optical properties to fit a desired function or application. The most straightforward approach is to chemically or physically modify the surface exposed to incident light. An effective method of surface modification is based on the addition of core‐shell structures at the surface. Of particular importance to many technological applications are core‐shell structures with dimensions comparable to the wavelengths of light extending from the UV up to the near‐IR region of the electromagnetic spectrum, which coincides with the major part of the solar spectrum. Surface modification approaches to tailor the optical properties of materials in this range of wavelengths are increasingly relevant in the context of materials and devices used in sustainable energy applications, such as solar cells and heat‐reflective paints. These materials are useful to mitigate the current energy and climate crises by allowing for enhanced energy harvesting and improved thermal management, respectively. Here, recent progress in the fabrication and application of core‐shell micro‐/nano‐structures for the modification of light interaction with surfaces is highlighted. Some limitations and future directions for the design of core‐shell materials are also discussed.

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“…Fluorite-type compounds are technologically promising materials, among which the alkaline-earth fluorides MF 2 (M = Ca and Mg) are of great importance due to their applications in many fields ranging from optics, spectroscopy, and heterogeneous catalysis to chemical and environmental processes. − A variety of synthetic approaches have been used for the preparation of high surface area metal fluorides. − The sol–gel procedure has been proven to be effective for both CaF 2 and MgF 2 , − exhibiting high surface area and distinct acidic properties, allowing them to perform as heterogeneous catalysts on different applications including Lewis acid catalyzed reactions. Therefore, it is vital to understand at a molecular level the physical and chemical properties of their different exposed surfaces. − …”

Section: Introductionmentioning

confidence: 99%

Adsorption of Water Molecule on Calcium Fluoride and Magnesium Fluoride Surfaces: A Combined Theoretical and Experimental Study

et al. 2020

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The adsorption and dissociation of H2O molecule on various surfaces of MgF2 and CaF2 have been investigated theoretically by using a dispersion-corrected density functional theory based method. The calculated adsorption energy of H2O molecule on the low index CaF2(110) and CaF2(111) surfaces ranges from −0.20 to −0.50 eV, smaller than those on the low index MgF2(001) and MgF2(110) with values from −0.80 to −1.06 eV. The modeling shows that the dissociation of water molecule is possible on the high index CaF2(210) surface and the low index MgF2(001) and MgF2(110) surfaces as revealed by the calculations that the dissociated states of H2O are thermodynamically more stable. Furthermore, for MgF2(001) and MgF2(110) surfaces, the dissociation process is almost barrierless, suggesting that the OH groups on the surfaces could be formed easily. These theoretical predictions suggest that MgF2 is superior to CaF2 in terms of water adsorption affinity, and high temperatures may be needed to remove the adsorbed water molecules and the OH groups on the surfaces, which were confirmed by the in situ FT-IR spectra of the synthesized MgF2 and CaF2 samples. The broad peak for CaF2 ranging from 3100 to 3600 cm–1 can be completely removed with a temperature of 573 K, while a higher temperature of 923 K is required for MgF2.

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Single compound in-situ synthesis of core-shell CaF2 nanoparticles based broad band antireflective coatings for solar energy conversion

Cited by 14 publications

References 31 publications

Bimodal Ultrasound and X-ray Bioimaging Properties of Particulate Calcium Fluoride Biomaterial

Bimodal Ultrasound and X-ray Bioimaging Properties of Particulate Calcium Fluoride Biomaterial

Core‐Shell Micro‐ and Nano‐Structures for The Modification of Light‐Surface Interactions

Adsorption of Water Molecule on Calcium Fluoride and Magnesium Fluoride Surfaces: A Combined Theoretical and Experimental Study

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