Growth and characterization of sodium pentaborate [Na(H4B5O10)] single crystals.
The bulk single crystals of sodium pentaborate [Na(H4B5O10)] were grown by slow evaporation solution growth technique using deionized water as solvent. The grown crystal was confirmed by single crystal X-ray diffraction studies. The structural perfection of the grown crystals has been analyzed by high resolution X-ray diffraction (HRXRD) studies by recording rocking curve. The photoluminescence (PL), UV-vis spectral studies were performed and the optical bandgap of the material was calculated. The presence of the functional groups was identified by FT-IR measurement. The factor group analysis was done on Na(H4B5O10) to reveal the vibrational optical modes. The thermal and mechanical properties of the grown crystal were studied by TG-DTA and Vickers microhardness tester, respectively. The dielectric behavior of Na(H4B5O10) was investigated with different frequencies and temperatures.
Urea doped crystals formed with potassium–sodium pentaborate (K 0.5 Na 0.5 B5)
Abstract Mixed crystal formed with potassium and sodium pentaborates (K0.5Na0.5B5 crystal) is expected to be an interesting material. In order to understand the effect of urea as an impurity on the structural, optical and electrical properties of K0.5Na0.5B5 crystal, pure and urea doped (separately in 3 different concentrations, viz. 0.25, 0.50 and 0.75 wt%)K0.5Na0.5B5 single crystals were grown by the slow solvent evaporation method and characterized. X-ray diffraction (both single crystal and powder) and FTIR and EDX spectral measurements were carried out to characterize chemically and structurally the grown (pure + 3 urea doped) crystals. UV–Vis spectral and second harmonic generation (SHG) efficiency measurements were carried out to characterize the grown crystals optically. Dielectric measurements were carried out at various temperatures in the range of 30–90 °C with different frequencies in the range of 100 Hz–1 MHz. Results obtained indicate that urea doping enhances the optical absorption, window wavelength range and SHG efficiency of the K0.5Na0.5B5 crystal. Also, urea doping leads to significantly tuned electrical properties.
Surface roughness monitoring by singular spectrum analysis of vibration signals
Abstract This study assessed two methods for enhanced surface roughness (Ra) monitoring based on the application of singular spectrum analysis (SSA) to vibrations signals generated in workpiece-cutting tool interaction in CNC finish turning operations i.e., the individual analysis of principal components (I-SSA), and the grouping analysis of correlated principal components (G-SSA). Singular spectrum analysis is a non-parametric technique of time series analysis that decomposes a signal into a set of independent additive time series referred to as principal components. A number of experiments with different cutting conditions were performed to assess surface roughness monitoring using both of these methods. The results show that singular spectrum analysis of vibration signal processing discriminated the frequency ranges effective for predicting surface roughness. Grouping analysis of correlated principal components (G-SSA) proved to be the most efficient method for monitoring surface roughness, with optimum prediction and reliability results at a lower analytical-computational cost. Finally, the results show that singular spectrum analysis is an ideal method for analyzing vibration signals applied to the on-line monitoring of surface roughness.