naa a22 4500 51080053X CHVBK 20180411083353.0 cr unu---uuuuu 180411e20130101xx s 000 0 eng 10.1007/s11664-012-2303-3 doi (NATIONALLICENCE)springer-10.1007/s11664-012-2303-3 Synthesis of Nanocrystalline CaWO4 as Low-TemperatureCo-fired Ceramic Material: Processing, Structural and Physical Properties [Elektronische Daten] [S. Vidya, Sam Solomon, J.K. Thomas] Nanocrystalline scheelite CaWO4, a promising material for low-temperature co-fired ceramic (LTCC) applications, has been successfully synthesized through a single-step autoignition combustion route. Structural analysis of the sample was performed by powder x-ray diffraction (XRD), Fourier-transform infrared spectroscopy, and Raman spectroscopy. The XRD analysis revealed that the as-prepared sample was single phase with scheelite tetragonal structure. The basic optical properties and optical constants of the CaWO4 nanopowder were studied using ultraviolet (UV)-visible absorption spectroscopy, which showed that the material was a wide-bandgap semiconductor with bandgap of 4.7eV at room temperature. The sample showed poor transmittance in the ultraviolet region but maximum transmission in the visible/near-infrared regions. The photoluminescence spectra recorded at different temperatures showed intense emission in the green region. The particle size estimated from transmission electron microscopy was 23nm. The feasibility of CaWO4 for LTCC applications was studied from its sintering behavior. The sample was sintered at a relatively low temperature of 810°C to high density, without using any sintering aid. The surface morphology of the sintered sample was analyzed by scanning electron microscopy. The dielectric constant and loss factor of the sample measured at 5MHz were found to be 10.50 and 1.56×10−3 at room temperature. The temperature coefficient of the dielectric constant was −88.71ppm/°C. The experimental results obtained in this work demonstrate the potential of nano-CaWO4 as a low-temperature co-fired ceramic as well as an excellent luminescent material. TMS, 2012 CaWO4 nationallicence LTCC nationallicence dielectric nationallicence sintering nationallicence combustion synthesis nationallicence Vidya S. Electronic Materials Research Laboratory, Department of Physics, Mar Ivanios College, 695 015, Thiruvananthapuram, Kerala, India aut Solomon Sam Department of Physics, St. John's College, 691306, Anchal, Kollam, Kerala, India aut Thomas J.K. Electronic Materials Research Laboratory, Department of Physics, Mar Ivanios College, 695 015, Thiruvananthapuram, Kerala, India aut Journal of Electronic Materials Springer US; http://www.springer-ny.com 42/1(2013-01-01), 129-137 0361-5235 42:1<129 2013 42 11664 https://doi.org/10.1007/s11664-012-2303-3 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11664-012-2303-3 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Vidya S. Electronic Materials Research Laboratory, Department of Physics, Mar Ivanios College, 695 015, Thiruvananthapuram, Kerala, India aut NATIONALLICENCE 700 1- Solomon Sam Department of Physics, St. John's College, 691306, Anchal, Kollam, Kerala, India aut NATIONALLICENCE 700 1- Thomas J.K. Electronic Materials Research Laboratory, Department of Physics, Mar Ivanios College, 695 015, Thiruvananthapuram, Kerala, India aut NATIONALLICENCE 773 0- Journal of Electronic Materials Springer US; http://www.springer-ny.com 42/1(2013-01-01), 129-137 0361-5235 42:1<129 2013 42 11664 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer