Hydrofluoric acid

About: Hydrofluoric acid is a research topic. Over the lifetime, 5577 publications have been published within this topic receiving 51599 citations. The topic is also known as: Hydrofluoric acid.

Method for producing purified silicon fine particles

Abstract: The present invention addresses the problem of providing a method for producing purified silicon fine particles which are hardly affected by a trace amount of water. In a method for producing purified silicon fine particles according to the present invention, silicon fine particles obtained by a vapor phase synthesis method are treated with hydrofluoric acid in the presence of an organic solvent having compatibility with water. The silicon fine particles include chlorine in a proportion of 0.1-10.0 mass% and oxygen in a proportion of 0.5-6.0 mass%. The obtained purified silicon fine particles have a specific surface area of at least 10 m2/g, an average crystallite diameter of less than 40 nm, a chlorine concentration of 1-10 mass% with respect to the weight of the fine particles, and a ratio (Co/S) of an oxygen concentration (Co: mass%) to a specific surface area (S: m2/g) of less than 0.025.

Non-destructive testing of subsurface damage for early indication of laser-induced damage threshold in fused silica

Abstract: Subsurface damage (SSD) in optical components is almost unavoidably caused by mechanical forces involved during grinding and polishing and can be a limiting factor, particularly for applications that require high laser powers. In this contribution, non-destructive characterization techniques are evaluated with respect to their capability to determine SSD in fused silica. For this, differently polished surfaces with different SSD levels have been prepared. An initial destructive analysis using etching in hydrofluoric acid in combination with white light interferometry revealed a high amount of SSD in one of the sample types compared to a very low amount of SSD in a second one. It is shown that nondestructive absorption as well as scattering measurements are sensitive towards SSD related differences in the samples. Finally, laser-induced damage tests proved a significant impact of SSD on the laser stability by determining a reduced damage threshold of 31 ± 3 J/cm² for the sample with high amount of SSD compared to 45 ± 5 J/cm² for the high-quality polished sample.

The effect of immersion time on singlemode-tapered multimode-singlemode (STMS) fabrication using a chemical etching method

Abstract: Singlemode-Multimode-Singlemode (SMS) is one of the fiber optic sensor structures that is widely applied for many sensing applications. High sensitivity is the preferred characteristic of SMS fiber structure. In this paper, a tapered structure is introduced to the SMS fiber structure to increase its performance. The tapered structure is made by the etching method by immersing the SMS multimode fiber in hydrofluoric acid (HF) solution. The immersion time was varied 5, 10, 15 and 20 minutes. The diameter of the multimode fiber decreases with the longer immersion time, while the length does not change. The STMS transmission spectrum was measured to investigate its performance. The chemical etching method using HF solution for tapering the SMS fibers has great potential as a simple method to achieve a smaller radius without lengthening multimode fibers.

Электрохимические характеристики анодов литий-ионных аккумуляторов на основе моноокиси кремния: влияние диспропорционирования и обработки в HF

Abstract: Composite SiO/C anodes for lithium-ion batteries (LIB) obtained by carbonization of silicon monoxide with fluorocarbon were investigated. Preliminary modification of the initial silicon monoxide was carried out by disproportionation and subsequent treatment in hydrofluoric acid. The study of the elemental composition of modified SiO and the electrochemical performance of composite anodes made from it showed that the oxygen content in the oxide matrix played a decisive role in changing their behavior. Depletion of its oxygen as a result of treatment in HF had a beneficial effect, leading to higher stability of the electrodes during cycling, an increase in their capacity, coulombic efficiency and rate capability.