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.
Third order nonlinear optical properties and optical limiting behaviour of sodium penta borate
Studies on third order optical nonlinearity of solution grown inorganic single crystal of sodium penta borate (NaB5) was carried out by z-scan technique with Nd:YAG laser (532 nm, 50 mW). The closed aperture z-scan measurement results peak valley pattern in normalized transmittance indicates the negative nonlinear refractive index due to self-defocusing nature and the nonlinear absorption is regarded as saturable absorption due to maximum transmittance lies near the focus in open aperture curve. The third order nonlinear optical parameters refractive index, nonlinear absorption coefficient and nonlinear susceptibility were found to be −1.28 × 10− 10 cm2/W, −7.91 × 10− 6 cm/W and 2.07 × 10− 7 esu. The optical constants (refractive index (n), reflectance (R), extinction coefficient (K), optical and electrical conductivity) of NaB5 crystals were determined by theoretical calculations from UV–Visible studies. The optical limiting property also studied for grown crystal and the limiting threshold values was found to be 35 mW.
Vibrational studies of molybdates, tungstates and related compounds—II: New Raman data and assignments for the scheelite-type compounds
Abstract New experimental data on pure compounds, isotopic species and solid solutions lead to more detailed and, in some cases, to revised assignments for the Raman spectrum of scheelite-type molybdates and tungstates. The 92Mo-100Mo isotopic shifts allow a more reliable assignment of the 2 types of internal bending modes, namely v4 and v2; it is found that v4 ⪢ v2; this is the reverse of the i.r. active modes, for which isotopic data show that v2 ⪢ v4. Thus, such assignments cannot be made by comparison. Likewise, the investigation of isotopic species and solid solutions leads to an easy discrimination between the rotational and the translational modes. Moreover, it appears that, for the lighter cations Ca and Sr at least, the 2 lowest-lying translational modes are essentially related to Mo-Mo (or W-W) motions, whereas the 2 highest-lying frequencies are related to a cation-cation (Ca-Ca or Sr-Sr) translation. This separation of the translations has only a practical significance, since it is not imposed by symmetry considerations; it is no longer really significant for the compounds of the heavy cations Ba and Pb. Some aspects of the relations between the internal frequencies and the nature of the cations are also discussed.