Shiv Prakash Singh

Nanometal-Glass Hybrid Nanocomposites: Synthesis, Properties and Applications

In recent past research on nanometal-glass hybrid composites has been the centre of attention across the globe particularly in the area of nanoscience and for the future nanotechnology. In this review, with a short historical background, its preparation by various multi-step techniques, properties and applications are briefly described. In addition, recently developed single-step in situ thermochemical reduction methodology by these authors for synthesis of various nanometal-glass hybrid nanocomposites are described in detail with their significant characteristic properties, relevant theories and applications. Here Au, Ag and Bi metals are considered and the synthesized glasses are mostly based on antimony, bismuth and phosphorus oxides. Some of them are dichroic in nature, that is, they exhibit blue to green colourations in transmitted light and brown to reddish brown colourations in reflected light. The appropriate reasons for their dichroic character are still remained unsolved. Nanometal-antimony oxide glass nanocomposites have been found to enhance the photoluminescence upconversion intensities up to 11 fold when co-doped with rare earth (RE) ions due to the plasmonic induced local field as enhanced by the effects of doped metal nanoparticles. The nanometal-glass hybrid nanocomposites, therefore, seem to be very promising for various nanophotonic applications (such as nanometal enhanced rare earth luminescence, solar cell, light emitting diode, plasmonic integrated circuit, plasmon slot waveguide, etc) that have presently emerged into a major field called ‘plasmonics’.

Photoluminescence enhancement of Eu3+ by energy transfer from Bi2+ to Eu3+ in bismuth glass nanocomposites

Bi2+-enhanced photoluminescence of Eu3+ doped Bi0-bismuth glass nanocomposites are demonstrated here. The generation of bismuth nanoparticles (NPs) and its typical surface plasmon resonance at 460 nm are controlled by the oxidative method instead of the conventional reduction technique during melt-quench processing. TEM images evidence the presence of spherical Bi0 NPs of 10–15 nm sizes and SAED pattern reveals their crystalline rhombohedral phase formation. The enhanced photoluminescence of Eu3+ is found to occur at 613 and 703 nm due to 5D0→7F2 and 5D0→7F4 transitions respectively. We believe that it has happened due to energy transfer from Bi2+ to Eu3+.

Influence of SiO(2) and Al(2)O(3) Fillers on Thermal and Dielectric Properties of Barium Zinc Borate Glass Microcomposites for Barrier Rib of Plasma Display Panels (PDPs)

In a lead-free low temperature sinterable multicomponent barium zinc borate glass system, BaO-ZnO-B2O3-SiO2-Li2O-Na2O (BZBSLN), the influence of SiO2 (amorphous) and Al2O3 (crystalline, α-alumina) ceramic fillers on the softening point (Ts), glass transition temperature (Tg), coefficient of thermal expansion (CTE), and dielectric constant (εr) has been investigated with a view to its use as the barrier ribs of plasma display panels (PDPs). The interaction of fillers with glass which occurred during sintering at 570°C has also been studied by XRD and FTIR spectroscopic analyses. It is observed that the filler has partially dissolved in the glass at the sintering temperature leaving some residual filler which results in ceramic-glass microcomposites. The distribution of fillers in the glass matrix and microstructures of the composites have been analyzed by SEM images. It has been seen that the Ts, Tg, CTE and εr slightly increased with the increase of Al2O3 content. In the case of SiO2 filler, the Ts and Tg gradually increased whereas CTE and εr gradually decreased along with the addition of SiO2. These experimentally measured properties have also been compared with the theoretically predicted values. Both the experimental and theoretical predictions of these properties with added filler contents have been found to be correlated very well. In consideration of the desired properties of barrier rib of PDPs with respect to use on PD200 glass substrates, the addition of Al2O3 filler to BZBSLN glass has been found to be more preferable than SiO2 filler.