Journal Article

PUBDB-2024-06361

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Synthesis, nanocrystalline morphology, lattice dynamics and nonlinear optics of mesoporous

Shchur, Y. (Corresponding author) ; Karout, H. E. ; Sahraoui, B. ; Andrushchak, A. ; Beltramo, G. ; Pustovyi, D. ; Vitusevich, S. ; Huber, P.Extern*DESY* ; Kityk, A. V.

2024
Macmillan Publishers Limited, part of Springer Nature [London]

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Please use a persistent id in citations: doi:10.1038/s41598-024-75686-6  doi:10.3204/PUBDB-2024-06361

Abstract: We demonstrate a hybrid nanocomposite combining mesoporous silica, pSiO$_2$, as a host medium and guest lithium niobate LiNbO$_3$ nanocrystals embedded into tubular silica nanochannels by calcination of the precursor mixed solution of lithium and niobium salts. High-resolution transmission electron microscopy, X-ray diffraction and Raman scattering techniques reveal trigonal LiNbO3 nanocrystals within the pSiO$_2$ nanochannels, indicating their random texture morphology. Annealing at high temperatures ( 950◦C) during calcination also leads to partial crystallization of the pSiO$_2$ matrix with the formation of trigonal α-SiO$_2$ nanocrystals. The Raman microscopy analysis of the pSiO$_2$:LiNbO$_3$ nanocomposite reveals three structural crystalline phases, α − SiO$_2$, LiNbO$_3$ and a mixed phase which involves the α-SiO$_2$ phase of host membrane and LiNbO$_3$ nanocrystals embedded into the membrane. The finite size of the LiNbO$_3$ nanocrystals results in specific features of the LO-TO phonon frequency splitting, which are investigated by Raman microscopy. In the transmission geometry, the second harmonic generation emission exhibits no Maker fringes and is characterized by a broad angular diagram of diffusely scattered light. The second harmonic generation response is independent of the polarization direction of the incident pump light, thus indicating a spatial isotropy of the nonlinear optical conversion in the pSiO$_2$:LiNbO$_3$ composite, consistent with the randomly oriented textural morphology of the deposited LiNbO$_3$ nanocrystals. The contribution of the guest LiNbO$_3$ nanocrystals to the second harmonic generation effect was found to be strongly dominant compared to the partially crystallized host pSiO$_2$ matrix. The nanocomposite pSiO$_2$:LiNbO$_3$ membrane, set in the 90◦ nonlinearoptical geometry, shows unusually high diffusely transmitted second harmonic generation light (back-reflected emission), apparently supported by internal light reflection from the tubular nanochannel network. Despite the fundamental interest, the revealed anomalous back-reflected second harmonic generation emission from pSiO$_2$:LiNbO$_3$ nanocomposite membranes expands the prospects for their photonic and nonlinear optical applications.

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Contributing Institute(s):

1. CIMMS-RA Center for integr. Multiscale M (CIMMS)
2. FS-Photon Science (FS-PS)

Research Program(s):

1. 631 - Matter – Dynamics, Mechanisms and Control (POF4-631) (POF4-631)
2. SFB 986 B07 - Polymere in grenzflächenbestimmten Geometrien: Struktur, Dynamik und Funktion an planaren und in porösen Hybridsystemen (B07) (318019437) (318019437)

Experiment(s):

1. No specific instrument

Appears in the scientific report 2024

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