IR@CGCRI - Central Glass and Ceramic Research Institute (CSIR)
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Phase determination of ZrB2-B4C ceramic composite material using XRD and rietveld refinement analysis
No full textIn this work, the Spark plasma sintering technique has been used to sinter ZrB2-B4C (20 wt%) composite at 2100 degrees C and 50 MPa uniaxial pressure for 15 min soaking in an argon atmosphere. XRD analysis has been carried out on the sintered sample to analyze the different phases present in the ZrB2-B4C composite. The Rietveld refinement technique has been used to analyze the crystal structure, the unit cell information such as space group, cell position, cell angles and atomic distances of the composite material using FULLPROF software. (C) 2019 Elsevier Ltd. All rights reserved
Development of antibiotic loaded mesoporous bioactive glass and its drug release kinetics
No full textAim of the study was to develop an efficient alternative for bone infections obtained during or after reconstruction surgeries using third generation antibiotic ceftriaxone and sulbactam sodium (CFS)] loaded mesoporous bioactive glass (MBG) nanopowders. MBG nanopowders were prepared using cationic surfactant CTAB by wet chemical process, which gave spherical morphology ( < 125 nm), high surface area (473.2 m(2)/g) and pore volume (0.27 c.c./g). Antibiotic loading to powders was performed through vacuum infiltration followed by freeze drying process and loading efficiency was found to be similar to 40.4% calculated from TGA, verified by CHN analysis (similar to 39%). Other characterizations like XRD, FTIR and EDX also confirmed successful encapsulation of antibiotics into MBG. Antibiotic release kinetics from nanopowders was studied up to7 days in contact with three different buffers (pH 1.2, 4.9 and 7.4) to understand pH dependency of intercalated system. Finally, both the systems have been further studied for antibiotic susceptibility assay by observing `zone of inhibition' against gram positive and gram negative bacteria. We have found that variation in pH environment could slightly control antibiotics release kinetics in terms of clinical applications. We have noticed that CFS-MBG pallets were significantly able to inhibit both pathogens (S. aureus and E. coli) by creating clear `zone of inhibition'. In contrast, visible presence of zone of inhibition was absent in case of bare MBG samples. However elution rate of CFS was initially high followed by sustained release can contribute for treatment of local bone infection and diseases
Influence of gold nanoparticles on the nonlinear optical and photoluminescence properties of Eu2O3 doped alkali borate glasses
No full textAlkali borate glasses activated with trivalent europium ions and rooted with gold (Au) nanoparticles (NPs) were synthesised through a melt quenching process involving a selective thermochemical reduction and their applicability as photonic materials was assessed in detail. Non-linear optical (NLO) measurements were performed using a Z-scan approach in the wavelength range of 700-1000 nm. The open aperture Z-scan signatures for the Eu3+-containing glasses embedded with and without the Au NPs established a reverse saturable absorption (RSA) at all of the studied wavelengths ascribed to the two-photon absorption (2PA). Surprisingly, the nonlinear optical absorption switched to a saturable absorption (SA) with an increase in the concentration of AuCl3. With the incorporation of the Au NPs, the UV excited photoluminescence (PL) intensity of the Eu3+-doped glasses increased first as a consequence of the local field enhancement by the Au NPs, and subsequently decreased at a higher concentration of AuCl3 due to the reverse energy transfer from the Eu3+ ion to the Au-0 NPs. The electronic polarization effect of the host glass enhanced the D-5(0) -> F-7(4) transition intensity on the incorporation of the gold NPs owing to the gold NP-embedded glasses showing a deep-red emission. The NLO and PL studies suggested that the investigated glasses containing a 0.01 mol% of AuCl3 is practically appropriate for photonic applications
Synthesis and characterization of alpha alumina-natural apatite based porous ceramic support for filtration application
No full textThe present study reported the synthesis of low-cost ceramic membrane supports. They were prepared by an extrusion method using alumina/natural apatite blends and further consolidated by heat treatment. The chemical composition, structure and particle size of the starting materials were analyzed. The effect of the natural apatite content, as sintering agent, on the microstructure, porosity, flexural strength and linear shrinkage of the prepared supports were studied as a function of sintering temperature. The microstructure exhibited that the sintering temperature decreased with the increment of the apatite content. The porosity and the pore size were controlled by the sintering temperature and the apatite amount added to the starting mixture. The mechanical strength and the linear shrinkage increased with increasing the apatite and the firing temperature. The sample selected for filtration displayed good porosity (45.38%) and pore size of 1.35 mu m giving a high perme-ability 959.64 h(-1) m(-2) bar(-1)
Novel capacitive humidity sensing properties of cobalt chromite nanoparticles based thick film
No full textNovel and excellent humidity sensing properties of sol-gel prepared spinel cobalt chromite nanoparticles based microporous thick films reported for the first time. Microporous thick film was prepared by sintering a green tape of cobalt chromite prepared by tape casting which was subsequently sandwiched between two parallel silver electrodes to develop a capacitive humidity sensor. Developed sensors demonstrate excellent humidity sensing behavior in the range of 5 to 95% relative Humidity (RH) with an appreciable gain of 3 pF/%RH. Dielectric polarization of moisture molecules absorbed on the CoCr2O4 surface and condensed in the surface pores leads to an appreciable enhancement of dielectric constant hence the sensing properties. Various sophisticated experiments have been carried out to have an insight into its' physicochemical properties that culminates into the excellent moisture sensing abilities of the sensor
Structural, out-gassing and nanomechanical properties of super-hydrophobic transparent silica aerogels developed by ambient pressure drying for space application
No full textTransparent super-hydrophobic monolithic silica aerogels are prepared by the cost-effective ambient pressure drying. The drying of aerogel is performed at various temperatures ranging from 25 to 200 degrees C. Oxidation states of different silica aerogels are investigated by XPS which shows the presence of both SiO and SiO2 phases. Thermal stability of hydrophobic aerogel is found as similar to 320 degrees C investigated by TGA and DSC. The chemical bonds (i.e., -CH3) responsible for the hydrophobic (WCA > 170 degrees) nature of synthesized silica aerogels are identified by FTIR. Further, out-gassing properties of the silica aerogels have been investigated and they are found in limit for the space application. The highest hardness and Young's modulus are measured by the nanoindentation technique for the aerogel dried at 120 degrees C which has higher density, while density decreases for the aerogel dried at 200 degrees C and the corresponding nanomechanical properties are found to be lowest as expected