Jyotirmayee Satapathy

Synthesis and characterisation of MgxCu1–xNb2O6 (x = 0, 0·2, 0·4, 0·6, 0·8, 1) for LTCC application

Abstract A series of MgxCu1–xNb2O6 (x = 0, 0·2, 0·4, 0·6, 0·8, 1) columbites has been prepared using sol–gel technique. The samples were sintered at 900°C for 6 h to study the suitability for low temperature co-fired ceramics (LTCC) application. Structural characterisation of the prepared samples has been carried out using the X-ray diffraction method. Lattice parameters and densities have been calculated. Microscopic characterisation is studied using field emission scanning electron microscopy. Microwave dielectric properties like dielectric constant and Qf factor for all the compositions have been measured. Dielectric constant is found to fall between 5 and 10 with a Qf factor of 3000 to 17 000 GHz. Thermal properties like thermal conductivity and thermal coefficient of expansion (TCE) have been measured. While thermal conductivity is found to be of the order of 1–2 W m−1 K−1, TCE is of the order of 5–10×10−6 °C−1. The thermal properties and the application are not reported earlier for these compounds. These properties are found to match the required properties of LTCC.

Monitoring a local extreme weather event with the scope of hyperspectral sounding

Operational space-based hyperspectral Infrared sounders retrieve atmospheric temperature and humidity profiles from the measured radiances. These sounders like Atmospheric InfraRed Sounder, Infrared Atmospheric Sounding Interferometer as well as INSAT-3D sounders on geostationary orbit have proved to be very successful in providing these retrievals on global and regional scales, respectively, with good enough spatio-temporal resolutions and are well competent with that of traditional profiles from radiosondes and models fields. The aim of this work is to show how these new generation hyperspectral Infrared sounders can benefit in real-time weather monitoring. We have considered a regional extreme weather event to demonstrate how the profiles retrieved from these operational sounders are consistent with the environmental conditions which have led to this severe weather event. This work has also made use of data products of Moderate Resolution Imaging Spectroradiometer as well as by radiative transfer simulation of clear and cloudy atmospheric conditions using Numerical Weather Prediction profiles in conjunction with INSAT-3D sounder. Our results indicate the potential use of high-quality hyperspectral atmospheric profiles to aid in delineation of real-time weather prediction.

Anomaly in thermal characterization of CaxMg1-xNb2O6 (x =0,0.4,0.6,1) towards LTCC applications

Abstract Low temperature co-fired ceramics (LTCC), being the most advantageous technology related to the multilayer substrates for various applications, demands an extensive study of raw materials. In the present work, a series of CaxMg1−xNb2O6 (x =0, 0.4, 0.6, 1.0) were prepared using sol-gel synthesis route and sintered at a temperature of 900°C to study its applicability for LTCC technology. The phase formation has been confirmed using X-ray diffraction. Thermal properties like thermal conductivity and thermal expansion, which are very important aspects as the former defines the heat flow to avoid thermal instability in the layers and the latter provides the dimensional congruency of the dielectric material and the conductors, are studied here over high temperature range up to the firing temperature. Although the values are quite satisfactory from the application point view, the results have showed an anomaly over temperature. The anomalous thermal behavior was further analyzed using TG-DTA.

Elastic properties of Ca x Mg 1−x Nb 2 O 6 for LTCC (x=0,0.2,0.4,0.6,0.8,1)

A series of CaxMg1−xNb2O6 (x=0,0.2,0.4,0.6,0.8,1) columbites has been prepared using sol-gel technique. The samples were sintered at 9000C for 6 hours. Structural characterization of the prepared samples has been done using X-ray diffraction (XRD) method. To study their applicability in low temperature cofired ceramic (LTCC) technology, elastic properties have been characterized for mechanical compatibility. Elastic behaviour was investigated at 300 K, employing ultrasonic pulse transmission technique at 1 MHz. The values of elastic moduli and acoustic Debye temperature (μD) were computed from longitudinal and shear velocities. The measured values were corrected to zero porosity using Hasselman and Fulraths formula. The elastic constants of the samples, estimated using Modis heterogeneous metal-mixture rule, were also reported. The variation of elastic moduli was interpreted in terms of strength of interatomic bonding.