Axial vibration control (AVC) technique is powerful tool for melt activation by low-frequency oscillation of inert baffle submerged into melt [1]. It was demonstrated that AVC grown crystals strongly differs in many properties comparing with the crystals grown by conventional directional solidification methods both Bridgman [2] and Czochralski [3] techniques.

Single crystals of LiNO₃-NaNO₃ solid solutions were grown by AVC-CZ technique [3] using 0.3 mm amplitude and 0-25 Hz frequency oscillations of an inert aluminum disk in the melt. The crystal diameter was 30-35 mm with 30-35 mm length of every part grown at fixed AVC parameters. To analyze impurities distributions in crystals we cut them along. then cut a slice perpendicular to the growth axis [006], and then cut into small pieces 3x3x2 mm. Every piece was dissolved and analyzed using ICP-MS technique (NexION 300 D, Perkin Elmer). Thus, we got a distribution of all impurities in the crystal.

The problem of different molecular weight impuirities distribution at crystal growth is very important for homogeneous doping. AVC technique produces vibrational flows in the melt could strongly change the impurity distribution pattern. We observed that various impurities acted differently at AVC application. Light molecular weight impurities (presented by Li) demonstrated significant leveling of concentration inside the crystal volume simultaneously with an increase of segregation coefficients (fig.1a). The similar leveling was observed for middle molecular weight impurities (presented by K) but their segregation coefficients changed insufficient (fig.1b). In case of heavy molecular weight impurities (presented by Ba) we also observed their concentration leveling (fig.1c) but segregation coefficients were nearly the same as for the conventional CZ grown crystals.

Effect of vibrational intensity (I=A×f²) on vibrone and optical characteristics, microhardness, dislocation density of AVC-CZ LiNO₃-NaNO₃single crystals was studied. In case of AVC-CZ crystals we observed a decrease of dislocation density up to single values, an increase of microhardness up to 10 rel.% (fig.2), an increase of optical transmission up to 10 rel.% (fig. 3).

Fig.2 Microhardness  vs vibrational intensity of AVC-CZ grown (LiNO₃)_0,01 (NaNO₃)_0,99 crystals

Fig. 3. Transmission of AVC-CZ  (LiNO₃)_0,01(NaNO₃)_0,99 crystals grown at different frequencies and 0.3 mm amplitude

We also observed an oscillation leveling of different vibron modes analyzed from Raman spectra, which indicated on a decrease of structure defects in crystal.

Fig.4. Ratio of FWHM_2/FWHM₁ of different vibron modes vs vibrational intensity of AVC-CZ grown (LiNO₃)_0,01(NaNO₃)_0,99 crystals

The research was financially supported by Ministry of Education and Science of Russia by grant N 16.552.11.7046

[1] E.V. Zharikov In Crystal Growth Technology. Semiconductors and Dielectrics
(eds P. Capper and P. Rudolph), Wiley-VCH Verlag, Weinheim, 2010, 41-64
[2] Avetisov I. Kh., Mel’kov A. Yu., Zinov’ev A. Yu., Zharikov E. V. Crystallography Reports. 2005. V. 50. Suppl. 1. P. 124-129.
[3] I. Ch. Avetissov, A.P. Sadovskiy, E.A. Sukhanova, G.Yu. Orlova, I.A. Belogorokhov, E.V. Zharikov J. Cryst. Growth, 2012, 360, 167

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/28772 must be provided.

1. Сrystal growth of scheelite-like double tungstates and molybdates
2. Synthesis of the promising laser material Cr⁴⁺ doped LiGaSiO₄ nano-glass-ceramics
3. Czochralski grown large diameter Li₂MoO₄ single crystals
4. Influence of the prolonged oxidizing annealing onto the spectroscopic properties of Cr:Mg₂SiO₄ crystals
5. Energy efficiency and adaptability of the AVC technique
6. Optimization of vibrating baffle configuration at AVC-CZ crystal growth
7. Impurity Influence On Polytype Generation At SiC Vapor Growth
8. Nonstoichiometry and optical properties of ZnSe crystal grown from melt and vapor
9. Organic luminophor metal complex in inorganic glass matrix – a new hybrid material
10. VGF Growth of CdTe Crystal Assisted by Axial Vibration Control  Technique Under Controlled Cadmium Pressure
11. Nonstoichiometry of ZnTe and CdTe vapor grown crystals