Effects of Temperature on the Morphology and Optical Properties of Spark Discharge Germanium Nanoparticles

• Published in: Materials Vol. 13; no. 19; p. 4431
• Main Authors: Lizunova, Anna, Mazharenko, Anastasia, Masnaviev, Bulat, Khramov, Egor, Efimov, Alexey, Ramanenka, Andrei, Shuklov, Ivan, Ivanov, Viktor
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 05.10.2020; MDPI
• Subjects: Aerosols; Agglomerates; Cellulose; Chemical composition; Crystal structure; Electric sparks; Fourier transforms; Fractals; Germanium; germanium nanoparticles; Germanium oxides; Investigations; Mie scattering; Mie theory; Morphology; Nanoparticles; Optical properties; Particle size; Particle size distribution; Photoluminescence; Silicon; Sintering; spark discharge; Temperature effects; Transmission electron microscopy; Tube furnaces
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma13194431

We report the spark discharge synthesis of aerosol germanium nanoparticles followed by sintering in a tube furnace at different temperatures varying from 25 to 800 °C. The size, structure, chemical composition and optical properties were studied. We have demonstrated a melting mechanism of nanoparticles agglomerates, the growth of the mean primary particle size from 7 to 51 nm and the reduction of the size of agglomerates with a temperature increase. According to transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) data, primary nanoparticles sintered at temperatures from 25 to 475 °C basically have a structure of Ge crystals embedded in a GeOx amorphous matrix, as well as visible photoluminescence (PL) with the maximum at 550 nm. Pure germanium nanoparticles are prepared at temperatures above 625 °C and distinguished by their absence of visible PL. The shape of the experimental UV-vis-NIR extinction spectra significantly depends on the size distribution of the germanium crystals. This fact was confirmed by simulations according to Mie theory for obtained ensembles of germanium nanoparticles.