Anal Tarafder

Broadband Er 3+ emission in highly nonlinear Bismuth modified Zinc-Borate glasses

Broadband NIR emission from Er3+ in highly nonlinear zinc-bismuth-borate glasses with full width at half maximum reaching up to 106 nm is reported. The glass compositional effects on thermal, structural, optical and spectroscopic properties have been explored in view of all-optical communication applications. The Zero Dispersion Wavelength of these glasses is found to be varying from 1.46 to 2.26μm. The observed enhancement in fluorescence intensity, lifetime and quantum efficiency of 4I13/2 → 4I15/2 transition with bismuth addition is attributed to reduced multiphonon relaxations with decreased host phonon energy. The gain profile covering C and L-bands of communication windows suggests their potentiality in broad-band amplification.

Effects of nucleating agents on crystallization and microstructure of fluorophlogopite mica-containing glass–ceramics

The alteration of crystallization behavior, microstructure, and thermal properties of fluorophlogopite mica-containing glass–ceramics by nucleating agent is systematically studied. TiO2, TiO2xa0+xa0ZrO2, and ZrO2 have been doped as the nucleating agents in the SiO2–MgO–Al2O3–B2O3–K2O–MgF2 (BMAPS) glass system and prepared by the melt-quench technique. The glass without nucleating agent is also prepared to ascertain the influence of nucleating agent. Addition of nucleating agents effectively increases the softening as well as glass transition temperatures. From the DSC study, it is found that the fluorophlogopite mica crystallization exotherm exhibited in the temperature range 800–850xa0°C and the activation energy varies in the range 167–182xa0kJ/mol. The opaque mica glass–ceramics are derived from these BMAPS glasses by a controlled heat treatment process and heat treatment at 1050xa0°C is found to be optimum. The mica crystals were identified as fluorophlogopite for all the four BMAPS glasses by X-ray powder diffraction (XRD) and subsequently confirmed by FTIR spectroscopy. Excellent matching with fluorophlogopite crystal was obtained in Zirconia-containing glass–ceramic as perceived from the XRD and FTIR studies. The microstructure of interlocked card-like mica flake crystals is found to form as seen from scanning electron microscopy, and such microstructure is obtained when ZrO2 has been used as nucleating agent. Glass–ceramic without nucleating agent possesses Vickers hardness value 4.58xa0Gpa and it is increased with addition of the nucleating agent (5.67–6.56xa0GPa), ZrO2-containing glass–ceramic possess lower hardness (5.67xa0GPa) and better machinability. Therefore, ZrO2 is the most efficient nucleating agent to generate fluorophlogopite mica in these glass–ceramics useable for SOFC applications.

Synthesis and properties of ZnTe and Eu3+ ion co-doped glass nanocomposites

In this study, ZnTe (II-VI) semiconductor and Eu+3-ion co-doped borosilicate glass has been prepared in the SiO2-K2O-CaO-BaO-B2O3 glass system followed by controlled heat-treatment to produce glass nanocomposites. Glass transition temperature and crystallization peak temperature have been evaluated using DSC analysis. Dilatometric studies were carried out to evaluate thermal expansion co-efficient, glass transition temperature, and dilatometric softening temperature and found to be 10.7 × 10−6/K, 580°u2009C and 628°u2009C, respectively. TEM micrographs demonstrate formation of nano sized crystallites of less than 50u2009nm. The ZnTe crystal formation also established through selected area electron diffraction (SAED) analysis and high resolution images obtained through TEM studies. With increasing heat treatment time, optical transmission cut-off wavelength (λcut-off) shifted towards higher wavelength. Excitation spectra were recorded by monitoring emission at 613u2009nm corresponding to the 5D0 → 7F2 transition. An inten...

Transparent Nd 3+ -doped bismuth titanate glass-ceramic nanocomposites: Fabrication and properties

Nd3+-doped bismuth titanate, (Bi4Ti3O12) (BiT) containing transparent glass-ceramics has been prepared by the melt-quenching followed by heat-treatment in the SiO2-K2O-Bi2O3-TiO2 (SKBT) system. The structural properties of the heat-treated GC are investigated using XRD, FE-SEM, TEM and FT-IR reflectance spectroscopy. The emission intensity of the 4F3/2→4I11/2 transition at 1065 nm is enhanced by 9-fold due to entering of Nd3+ ions (r = 0.98 A) into the low-phonon crystalline phase (BiT), possibly by replacing Bi3+ ions (r = 1.02 A) of the same valency. An increase of er value (from 18.5 to 32.93) was observed with increase in heat-treatment time.

Compositional dependence of ultrasonic velocities in glasses

This paper analyzes the variation of ultrasonic wave velocities in glasses with change in compositions based on the variation of Poisson’s ratio (ν) and fractal bond connectivity (d) of these glasses. It shows that for the same Poisson’s ratio value, the ratio of ultrasonic shear wave velocity to longitudinal velocity is independent of the composition and varies linearly with the longitudinal velocity. The suggested linear variation of velocity ratio with longitudinal velocity shows a good agreement with the experimental data obtained from the previously published studies.

Advanced Glass-Ceramic Nanocomposites for Structural, Photonic, and Optoelectronic Applications

In this chapter, recent developments in the area of glass-ceramic (GC) nanocomposites for structural, photonic, and optoelectronic applications were described. These nanoglass-ceramics, doping with rare-earth (RE 3xa0+ ) ions or without doping, were prepared by adopting the melt-quenching technique followed by their respective heat-treatment protocol. Precursor glasses and the heat-treated nanoglass-ceramics were characterized by differential scanning calorimetry (DSC)/differential thermal analysis (DTA), X-ray diffraction, absorption and photoluminescence spectra, dielectric constant, transmission electron microscopy, selected area electron diffraction (SAED) and field emission scanning electron microscopy, hardness, etc. measurements. β-Quartz solid solution and spinel (MgAl 2 O 4 ) GC nanocomposites were considered for structural applications. For photonic applications yttrium aluminum garnet (YAG, Y 2 Al 5 O 12 ), willemite (Zn 2 SiO 4 ), and oxyhalide GCs were described. Ferroelectric lithium tantalate (LiTaO 3 ), potassium niobate (KNbO 3 ), bismuth titanate (Bi 4 Ti 3 O 12 ), barium bismuth titanate (BaBi 4 Ti 4 O 15 ), and strontium bismuth tantalate (SrBi 2 Ta 2 O 9 ) GC nanocomposites were described for optoelectronic applications. Their thermal, physical, optical, mechanical, and dielectric properties were delineated with evolution of their nanostructuring. Their applications are also described.

Nano Gold (Au0) and Au0-Er3+ Containing Plasmonic K2O-ZnO-SiO2 Glass Nanocomposites: Processing and Properties

ABSTRACT In this paper, nano gold (Au) and nano gold-erbium (Au-Er) co-embedded potassium zinc silicate based monolithic plasmonic glass nanocomposites have been evaluated. These plasmonic glass nanocomposites of Au were prepared by a controlled heat-treatment of the K2O-ZnO-SiO2 glasses obtained by melt-quench technique. Differential scanning calorimeter, dilatometer, ultra violet-visible absorption spectrophotometer, X-ray diffractometer, transmission electron microscope, Fourier transform infrared spectrometer, prism coupler and spectrofluorimeter were used to characterize the glasses and heat-treated glass nanocomposites. A gradual creation of more Au0 nanoparticles with prolongation of heat-treatment time resulted in strong surface plasmon resonance band around 520 nm in the glass nanocomposite samples. Decreased photoluminescence spectral intensities of Er3+ ion around 550 and 1540 nm due to 2H11/2, 4S3/2 → 4I15/2 and 4I13/2 → 4I15/2 emission transitions were observed with increase in heat-treatment time. The decrease in emission intensity was caused due to lower excitation spectral intensity of Er3+ ions and higher absorption intensity of Au0 nanoparticles around 523 nm with increase in heat-treatment time of the samples. GRAPHICAL ABSTRACT

Silver Glass Nanocomposites: Preparation, Properties, and Applications

Abstract In this chapter, several recent findings on silver glass nanocomposites (NCs) are presented. Here, the silver (Ag) containing NCs were prepared by the melt-quenching technique in the silicate, borosilicate, and chloroborosilicate glass systems using antimony oxide (Sb2O3) and tin oxide (SnO) as the reducing agent followed by heat treatment. Effects of heat-treatment time and concentration of silver and reducing agent on the shape, size, and number density of the generated silver nanoparticles were investigated by analyzing the UV-vis and photoluminescence spectra, X-ray diffraction patterns, refractive index, transmission electron microscopic images, and selected area electron diffraction patterns. The results have been interpreted by the existing theories and literature support. Applications of silver glass NCs in various devices and technologies are also described.

Anomalous properties of chloroborosilicate glasses in the K2O–BaO–Al2O3–B2O3–SiO2–BaCl2 system

A series of chloroborosilicate glass having composition (in mol%) (100 −x)(42SiO2–30B2O3–20BaO–4K2O–4Al2O3)–xBaCl2 (where x = 0−30) has been prepared by the melt quench technique yielding transparent monolithic glasses up to x = 22.5. Structural investigation by infrared reflection and UV–vis–NIR absorption revealed the bridging action of Cl atom and decrease in non-bridging oxygens with the increase in BaCl2 content. Thermal properties (Tg, Td and Ts) were measured by the dilatometry and softening point measurement. Viscosity was calculated using the Vogel–Fulcher–Tammann equation. Elastic constants were measured by the ultrasonic method. Other mechanical properties like hardness, fracture toughness were also measured. All of the thermal and mechanical properties exhibited a similar trend of anomalous variation as a function of the BaCl2 content, showing maxima at 10 mol% and a sharp increase at 25 mol% BaCl2 content. The anomaly has been explained by the structural point of view with the help of the aforementioned spectroscopic data.