1
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Bredillet K, Riporto F, Guo T, Dhouib A, Multian V, Monnier V, Figueras Llussà P, Beauquis S, Bonacina L, Mugnier Y, Le Dantec R. Dual second harmonic generation and up-conversion photoluminescence emission in highly-optimized LiNbO 3 nanocrystals doped and co-doped with Er 3+ and Yb 3. NANOSCALE 2024. [PMID: 38497193 DOI: 10.1039/d4nr00431k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Preparation from the aqueous alkoxide route of doped and co-doped lithium niobate nanocrystals with Er3+ and Yb3+ ions, and detailed investigations of their optical properties are presented in this comprehensive work. Simultaneous emission under femtosecond laser excitation of second harmonic generation (SHG) and up-conversion photoluminescence (UC-PL) is studied from colloidal suspensions according to the lanthanide ion contents. Special attention has been paid to produce phase pure nanocrystals of constant size (∼20 nm) thus allowing a straightforward comparison and optimization of the Er content for increasing the green UC-PL signals under 800 nm excitation. An optimal molar concentration at about 4 molar% in erbium ions is demonstrated, that is well above the concentration usually achieved in bulk crystals. Similarly, for co-doped LiNbO3 nanocrystals, different lanthanide concentrations and Yb/Er content ratios are tested allowing optimization of the green and red up-conversion excited at 980 nm, and analysis of the underlying mechanisms from excitation spectra. All together, these findings provide valuable insights into the wet-chemical synthesis and potential of doped and co-doped LiNbO3 nanocrystals for advanced applications, combining both SHG and UC-PL emissions from the particle core.
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Affiliation(s)
- K Bredillet
- Université Savoie Mont Blanc, SYMME, F-74000, Annecy, France.
| | - F Riporto
- Université Savoie Mont Blanc, SYMME, F-74000, Annecy, France.
| | - T Guo
- Université Savoie Mont Blanc, SYMME, F-74000, Annecy, France.
| | - A Dhouib
- Université Savoie Mont Blanc, SYMME, F-74000, Annecy, France.
| | - V Multian
- Université Savoie Mont Blanc, SYMME, F-74000, Annecy, France.
| | - V Monnier
- Univ. Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, CNRS, INL, UMR5270, 69130 Ecully, France
| | - P Figueras Llussà
- Department of Applied Physics, Université de Genève, 1211 Genève 4, Switzerland
| | - S Beauquis
- Université Savoie Mont Blanc, SYMME, F-74000, Annecy, France.
| | - L Bonacina
- Department of Applied Physics, Université de Genève, 1211 Genève 4, Switzerland
| | - Y Mugnier
- Université Savoie Mont Blanc, SYMME, F-74000, Annecy, France.
| | - R Le Dantec
- Université Savoie Mont Blanc, SYMME, F-74000, Annecy, France.
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2
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Riporto F, Dhouib A, Gheata A, Beauquis S, Molina E, Guené-Girard S, Galez C, Bornet A, Gautier-Luneau I, Gerber-Lemaire S, Monnier V, Le Dantec R, Mugnier Y. Nonclassical Nucleation and Crystallization of LiNbO 3 Nanoparticles from the Aqueous Solvothermal Alkoxide Route. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023:e2306417. [PMID: 37968253 DOI: 10.1002/smll.202306417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 10/09/2023] [Indexed: 11/17/2023]
Abstract
The exact molecular reaction pathway and crystallization mechanisms of LiNbO3 nanoparticles under solvothermal conditions are derived through extensive time- and temperature-resolved experiments allowing to track all the transient molecular and solid species. Starting with a simple mixing of Li/Nb ethoxides, water addition is used to promote condensation after ligand exchange with different co-solvents including alcohols and glycols of variable carbon-chain length. A nonclassical nucleation scheme is first demonstrated after the identification of new octanuclear complexes with a {Li4 Nb4 O10 } core whose solvophobic interactions mediate their aggregation, thus, resulting in a colloidal gel at room-temperature. Upon heating, a more or less frustrated aggregation-mediated crystallization process is then evidenced leading to LiNbO3 nanocrystals of adjustable mean size between 20 and 100 nm. Such a fine control can be attributed to the variable Nb-OR (R = alkoxy/glycoxy ligand) binding interactions at the surface of crystalline intermediates. Demonstration of such a nonclassical nucleation process and crystallization mechanism for LiNbO3 not only sheds light on the entire growth process of multifunctional nanomaterials with non-perovskite crystalline structures, but also opens new avenues for the identification of novel bimetallic oxoclusters involved in the formation of several mixed oxides from the aqueous alkoxide route.
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Affiliation(s)
- Florian Riporto
- Université Savoie Mont Blanc, SYMME, Annecy, F-74000, France
| | - Ameni Dhouib
- Université Savoie Mont Blanc, SYMME, Annecy, F-74000, France
| | - Adrian Gheata
- Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Group for Functionalized Biomaterials, Lausanne, 1015, Switzerland
| | | | - Emilie Molina
- Université Savoie Mont Blanc, SYMME, Annecy, F-74000, France
| | - Simon Guené-Girard
- Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, Grenoble, 38000, France
| | - Christine Galez
- Université Savoie Mont Blanc, SYMME, Annecy, F-74000, France
| | - Aurélien Bornet
- Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Nuclear Magnetic Resonance Platform, EPFL SB ISIC-NMRP, Batochime, Lausanne, 1015, Switzerland
| | | | - Sandrine Gerber-Lemaire
- Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Group for Functionalized Biomaterials, Lausanne, 1015, Switzerland
| | - Virginie Monnier
- Univ Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, CNRS, INL, UMR5270, Ecully, 69130, France
| | - Ronan Le Dantec
- Université Savoie Mont Blanc, SYMME, Annecy, F-74000, France
| | - Yannick Mugnier
- Université Savoie Mont Blanc, SYMME, Annecy, F-74000, France
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Gheata A, Spada A, Wittwer M, Dhouib A, Molina E, Mugnier Y, Gerber-Lemaire S. Modulating the Surface Properties of Lithium Niobate Nanoparticles by Multifunctional Coatings Using Water-in-Oil Microemulsions. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:522. [PMID: 36770484 PMCID: PMC9921616 DOI: 10.3390/nano13030522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/13/2023] [Accepted: 01/26/2023] [Indexed: 06/18/2023]
Abstract
Inorganic nanoparticles (NPs) have emerged as promising tools in biomedical applications, owing to their inherent physicochemical properties and their ease of functionalization. In all potential applications, the surface functionalization strategy is a key step to ensure that NPs are able to overcome the barriers encountered in physiological media, while introducing specific reactive moieties to enable post-functionalization. Silanization appears as a versatile NP-coating strategy, due to the biocompatibility and stability of silica, thus justifying the need for robust and well controlled silanization protocols. Herein, we describe a procedure for the silica coating of harmonic metal oxide NPs (LiNbO3, LNO) using a water-in-oil microemulsion (W/O ME) approach. Through optimized ME conditions, the silanization of LNO NPs was achieved by the condensation of silica precursors (TEOS, APTES derivatives) on the oxide surface, resulting in the formation of coated NPs displaying carboxyl (LNO@COOH) or azide (LNO@N3) reactive moieties. LNO@COOH NPs were further conjugated to an unnatural azido-containing small peptide to obtain silica-coated LNO NPs (LNO@Talys), displaying both azide and carboxyl moieties, which are well suited for biomedical applications due to the orthogonality of their surface functional groups, their colloidal stability in aqueous medium, and their anti-fouling properties.
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Affiliation(s)
- Adrian Gheata
- Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Group for Functionalized Biomaterials, 1015 Lausanne, Switzerland
| | - Alessandra Spada
- Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Group for Functionalized Biomaterials, 1015 Lausanne, Switzerland
| | - Manon Wittwer
- Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Group for Functionalized Biomaterials, 1015 Lausanne, Switzerland
- Département de Chimie, École Normale Supérieure, PSL University, 75005 Paris, France
| | - Ameni Dhouib
- Université Savoie Mont-Blanc, SYMME, 74000 Annecy, France
| | - Emilie Molina
- Université Savoie Mont-Blanc, SYMME, 74000 Annecy, France
| | | | - Sandrine Gerber-Lemaire
- Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Group for Functionalized Biomaterials, 1015 Lausanne, Switzerland
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4
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Gheata A, Gaulier G, Campargue G, Vuilleumier J, Kaiser S, Gautschi I, Riporto F, Beauquis S, Staedler D, Diviani D, Bonacina L, Gerber-Lemaire S. Photoresponsive Nanocarriers Based on Lithium Niobate Nanoparticles for Harmonic Imaging and On-Demand Release of Anticancer Chemotherapeutics. ACS NANOSCIENCE AU 2022; 2:355-366. [PMID: 35996436 PMCID: PMC9389616 DOI: 10.1021/acsnanoscienceau.1c00044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Nanoparticle-based
drug delivery systems have the potential for
increasing the efficiency of chemotherapeutics by enhancing the drug
accumulation at specific target sites, thereby reducing adverse side
effects and mitigating patient acquired resistance. In particular,
photo-responsive nanomaterials have attracted much interest due to
their ability to release molecular cargos on demand upon light irradiation.
In some settings, they can also provide complementary information
by optical imaging on the (sub)cellular scale. We herein present a
system based on lithium niobate harmonic nanoparticles (LNO HNPs)
for the decoupled multi-harmonic cell imaging and near-infrared light-triggered
delivery of an erlotinib derivative (ELA) for the treatment
of epidermal growth factor receptor (EGFR)-overexpressing carcinomas.
The ELA cargo was covalently conjugated to the surface
of silica-coated LNO HNPs through a coumarinyl photo-cleavable linker,
achieving a surface loading of the active molecule of 27 nmol/mg NPs.
The resulting nanoconjugates (LNO-CM-ELA NPs) were successfully
imaged upon pulsed laser excitation at 1250 nm in EGFR-overexpressing
human prostate cancer cells DU145 by detecting the second harmonic
emission at 625 nm, in the tissue transparency window. Tuning the
laser at 790 nm resulted in the uncaging of the ELA cargo
as a result of the second harmonic emission of the inorganic HNP core
at 395 nm. This protocol induced a significant growth inhibition in
DU145 cells, which was only observed upon specific irradiation at
790 nm, highlighting the promising capabilities of LNO-CM-ELA NPs for theranostic applications.
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Affiliation(s)
- Adrian Gheata
- Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Group for Functionalized Biomaterials, EPFL SB ISIC SCI-SB-SG, Station 6, Lausanne CH-1015, Switzerland
| | - Geoffrey Gaulier
- Department of Applied Physics, Université de Genève, 22 Chemin de Pinchat, Genève CH-1211, Switzerland
| | - Gabriel Campargue
- Department of Applied Physics, Université de Genève, 22 Chemin de Pinchat, Genève CH-1211, Switzerland
| | - Jérémy Vuilleumier
- Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Group for Functionalized Biomaterials, EPFL SB ISIC SCI-SB-SG, Station 6, Lausanne CH-1015, Switzerland
| | - Simon Kaiser
- Department of Biomedical Sciences, Université de Lausanne, 7 Rue du Bugnon, Lausanne CH-1005, Switzerland
| | - Ivan Gautschi
- Department of Biomedical Sciences, Université de Lausanne, 7 Rue du Bugnon, Lausanne CH-1005, Switzerland
| | | | | | - Davide Staedler
- Department of Biomedical Sciences, Université de Lausanne, 7 Rue du Bugnon, Lausanne CH-1005, Switzerland
| | - Dario Diviani
- Department of Biomedical Sciences, Université de Lausanne, 7 Rue du Bugnon, Lausanne CH-1005, Switzerland
| | - Luigi Bonacina
- Department of Applied Physics, Université de Genève, 22 Chemin de Pinchat, Genève CH-1211, Switzerland
| | - Sandrine Gerber-Lemaire
- Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Group for Functionalized Biomaterials, EPFL SB ISIC SCI-SB-SG, Station 6, Lausanne CH-1015, Switzerland
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5
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Chen K, Wu J, Hu Q, Lu Z, Sun X, Wang Z, Tang G, Hu H, Xue D. Omni-functional crystal: Advanced methods to characterize the composition and homogeneity of lithium niobate melts and crystals. EXPLORATION (BEIJING, CHINA) 2022; 2:20220059. [PMID: 37325602 PMCID: PMC10191049 DOI: 10.1002/exp.20220059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 06/16/2022] [Indexed: 06/17/2023]
Abstract
Lithium niobate (LN) is a type of multifunctional dielectric and ferroelectric crystal that is widely used in acoustic, optical, and optoelectronic devices. The performance of pure and doped LN strongly depends on various factors, including its composition, microstructure, defects, domain, and homogeneity. The structure and composition homogeneity can affect both the chemical and physical properties of LN crystals, including their density, Curie temperature, refractive index, and piezoelectric and mechanical properties. In terms of practical demands, both the composition and microstructure characterizations these crystals must range from the nanometer scale up to the millimeter and wafer scales. Therefore, LN crystals require different characterization technologies when verifying their quality for various device applications. Optical, electrical, and acoustic technologies have been developed, including x-ray diffraction, Raman spectroscopy, electron microscopy, and interferometry. To obtain detailed structural information, advanced sub-nanometer technologies are required. For general industrial demands, fast and non-destructive technologies are preferable. This review outlines the advanced methods used to characterize both the composition and homogeneity of LN melts and crystals from the micro- to wafer scale.
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Affiliation(s)
- Kunfeng Chen
- Institute of Novel SemiconductorsState Key Laboratory of Crystal MaterialsShandong UniversityJinanChina
| | - Ji'an Wu
- Institute of Novel SemiconductorsState Key Laboratory of Crystal MaterialsShandong UniversityJinanChina
| | - Qianyu Hu
- Institute of Novel SemiconductorsState Key Laboratory of Crystal MaterialsShandong UniversityJinanChina
| | - Zheng Lu
- Institute of Novel SemiconductorsState Key Laboratory of Crystal MaterialsShandong UniversityJinanChina
| | - Xiangfei Sun
- Institute of Novel SemiconductorsState Key Laboratory of Crystal MaterialsShandong UniversityJinanChina
| | - Zhiqiang Wang
- Institute of Novel SemiconductorsState Key Laboratory of Crystal MaterialsShandong UniversityJinanChina
| | - Gongbin Tang
- Institute of Novel SemiconductorsState Key Laboratory of Crystal MaterialsShandong UniversityJinanChina
| | - Hui Hu
- School of PhysicsState Key Laboratory of Crystal MaterialsShandong UniversityJinanChina
| | - Dongfeng Xue
- Multiscale Crystal Materials Research CenterShenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhenChina
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6
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Dantelle G, Beauquis S, Le Dantec R, Monnier V, Galez C, Mugnier Y. Solution-Based Synthesis Routes for the Preparation of Noncentrosymmetric 0-D Oxide Nanocrystals with Perovskite and Nonperovskite Structures. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2200992. [PMID: 35691941 DOI: 10.1002/smll.202200992] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 05/21/2022] [Indexed: 06/15/2023]
Abstract
With the miniaturization of electronic-based devices, the foreseen potential of new optical nanoprobes and the assessment of eventual size and shape effects, elaboration of multifunctional noncentrosymmetric nanocrystals with ferroelectric, pyroelectric, piezoelectric, and nonlinear optical properties are the subject of an increasing research interest. Here, the recent achievements from the solution-based methods (coprecipitation in homogeneous and nanostructured media, sol-gel processes including various chemistries and hydro/solvothermal techniques) to prepare 0-D perovskite and nonperovskite oxides in the 5-500 nm size range are critically reviewed. To cover a representative list of covalent- and ionic-type materials, BaTiO3 and its derivatives, niobate compounds (i.e., K/Na/LiNbO3 ), multiferroic BiFeO3, and crystals of lower symmetry including KTiOPO4 and some iodate compounds such as Fe(IO3 )3 and La(IO3 )3 are systematically in focus. The resulting size, morphology, and aggregation state are discussed in light of the proposed formation mechanisms. Because of a higher complexity related to their chemical composition and crystalline structures, improving the rational design of these multifunctional oxides in terms of finely-tuned compositions, crystalline hosts and structure-property relationships still need in the future a special attention of the research community to the detailed understanding of the reaction pathways and crystallization mechanisms.
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Affiliation(s)
- Géraldine Dantelle
- Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, Grenoble, 38000, France
| | | | - Ronan Le Dantec
- Université Savoie Mont Blanc, SYMME, Annecy, F-74000, France
| | - Virginie Monnier
- Univ Lyon, Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, CNRS, INL, UMR5270, Ecully, 69130, France
| | - Christine Galez
- Université Savoie Mont Blanc, SYMME, Annecy, F-74000, France
| | - Yannick Mugnier
- Université Savoie Mont Blanc, SYMME, Annecy, F-74000, France
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7
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Chikhaoui R, Hebboul Z, Fadla MA, Bredillet K, Liang A, Errandonea D, Beauquis S, Benghia A, Marty JC, Le Dantec R, Mugnier Y, Bandiello E. Synthesis and Characterization of Novel Nanoparticles of Lithium Aluminum Iodate LiAl(IO 3) 4, and DFT Calculations of the Crystal Structure and Physical Properties. NANOMATERIALS 2021; 11:nano11123289. [PMID: 34947638 PMCID: PMC8704596 DOI: 10.3390/nano11123289] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/26/2021] [Accepted: 11/29/2021] [Indexed: 01/02/2023]
Abstract
Here we report on the non-hydrothermal aqueous synthesis and characterization of nanocrystalline lithium aluminum iodate, LiAl(IO3)4. Morphological and compositional analyses were carried out by using scanning electron microscopy (SEM) and energy-dispersive X-ray measurements (EDX). The optical and vibrational properties of LiAl(IO3)4 have been studied by UV-Vis and IR spectroscopy. LiAl(IO3)4 is found to crystallize in the non-centrosymmetric, monoclinic P21 space group, contrary to what was reported previously. Theoretical simulations and Rietveld refinements of crystal structure support this finding, together with the relatively high Second Harmonic Generation (SGH) response that was observed. Electronic band structure calculations show that LiAl(IO3)4 crystal has an indirect band gap Egap=3.68 eV, in agreement with the experimental optical band gap Egap=3.433 eV. The complex relative permittivity and the refraction index of LiAl(IO3)4 have also been calculated as a function of energy, as well as its elastic constants and mechanical parameters. LiAl(IO3)4 is found to be a very compressible and ductile material. Our findings imply that LiAl(IO3)4 is a promising material for optoelectronic and non -linear optical applications.
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Affiliation(s)
- Rihab Chikhaoui
- Laboratoire Physico-Chimie des Matériaux (LPCM), Université Amar Telidji de Laghouat, BP 37G, Laghouat 03000, Algeria; (R.C.); (Z.H.)
| | - Zoulikha Hebboul
- Laboratoire Physico-Chimie des Matériaux (LPCM), Université Amar Telidji de Laghouat, BP 37G, Laghouat 03000, Algeria; (R.C.); (Z.H.)
| | - Mohamed Abdelilah Fadla
- Laboratoire de Physique des Matériaux, Université Amar Telidji de Laghouat, BP 37G, Laghouat 03000, Algeria; (M.A.F.); (A.B.)
| | - Kevin Bredillet
- SYstème et Matériaux pour la MÉcatronique (SYMME), University Savoie Mont Blanc, F-74000 Annecy, France; (K.B.); (S.B.); (J.C.M.); (R.L.D.); (Y.M.)
| | - Akun Liang
- Departamento de Física Aplicada—ICMUV—MALTA Consolider Team, Universitat de València, c/Dr. Moliner 50, 46100 Burjassot, València, Spain; (A.L.); (D.E.)
| | - Daniel Errandonea
- Departamento de Física Aplicada—ICMUV—MALTA Consolider Team, Universitat de València, c/Dr. Moliner 50, 46100 Burjassot, València, Spain; (A.L.); (D.E.)
| | - Sandrine Beauquis
- SYstème et Matériaux pour la MÉcatronique (SYMME), University Savoie Mont Blanc, F-74000 Annecy, France; (K.B.); (S.B.); (J.C.M.); (R.L.D.); (Y.M.)
| | - Ali Benghia
- Laboratoire de Physique des Matériaux, Université Amar Telidji de Laghouat, BP 37G, Laghouat 03000, Algeria; (M.A.F.); (A.B.)
| | - Jean Christophe Marty
- SYstème et Matériaux pour la MÉcatronique (SYMME), University Savoie Mont Blanc, F-74000 Annecy, France; (K.B.); (S.B.); (J.C.M.); (R.L.D.); (Y.M.)
| | - Ronan Le Dantec
- SYstème et Matériaux pour la MÉcatronique (SYMME), University Savoie Mont Blanc, F-74000 Annecy, France; (K.B.); (S.B.); (J.C.M.); (R.L.D.); (Y.M.)
| | - Yannick Mugnier
- SYstème et Matériaux pour la MÉcatronique (SYMME), University Savoie Mont Blanc, F-74000 Annecy, France; (K.B.); (S.B.); (J.C.M.); (R.L.D.); (Y.M.)
| | - Enrico Bandiello
- Departamento de Física Aplicada—ICMUV—MALTA Consolider Team, Universitat de València, c/Dr. Moliner 50, 46100 Burjassot, València, Spain; (A.L.); (D.E.)
- Correspondence:
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8
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Gold-seeded Lithium Niobate Nanoparticles: Influence of Gold Surface Coverage on Second Harmonic Properties. NANOMATERIALS 2021; 11:nano11040950. [PMID: 33917921 PMCID: PMC8068263 DOI: 10.3390/nano11040950] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 03/29/2021] [Accepted: 04/02/2021] [Indexed: 12/19/2022]
Abstract
Hybrid nanoparticles composed of an efficient nonlinear optical core and a gold shell can enhance and tune the nonlinear optical emission thanks to the plasmonic effect. However the influence of an incomplete gold shell, i.e., isolated gold nano-islands, is still not well studied. Here LiNbO3 (LN) core nanoparticles of 45 nm were coated with various densities of gold nano-seeds (AuSeeds). As both LN and AuSeeds bear negative surface charge, a positively-charged polymer was first coated onto LN. The number of polymer chains per LN was evaluated at 1210 by XPS and confirmed by fluorescence titration. Then, the surface coverage percentage of AuSeeds onto LN was estimated to a maximum of 30% using ICP-AES. The addition of AuSeeds was also accompanied with surface charge reversal, the negative charge increasing with the higher amount of AuSeeds. Finally, the first hyperpolarizability decreased with the increase of AuSeeds density while depolarization values for Au-seeded LN were close to the one of bare LN, showing a predominance of the second harmonic volumic contribution.
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