Synthesis, sintering and optical properties of CaMoO_4: A promising scheelite LTCC and photoluminescent material

摘要

The synthesis of nanocrystalline calcium molybdate (CaMoO_4) through an autoigniting combustion technique is reported in this paper. The structural characterization of the as-prepared nanocry stallites were done by X-ray diffraction (XRD), Fourier transform Raman, and Fourier transform infrared (IR) spectro-scopy and the morphological studies using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The studies reveal that the as-prepared powder itself was phase pure with tetragonal structure and of particle size 25 run. The sample was sintered at a relatively low temperature of 775 ℃to a high density of ～95% for the first time, without the use of any sintering aid. The optical bandgap energy calculated from the ultraviolet-visible absorption spectrum for the as-prepared and annealed sample was 3.72 and 3.99 eV, respectively. The photoluminescence spectra of the sample showed an intense emission in the green region (528 nm). The dielectric constant and loss factor of the sample at 5 MHz was found to be 11.00 and 6.40 × 10~(-3) at room temperature. The temperature coeficient of dielectric constant was -95.04 pp/℃. These observations reveal that nanostructured CaMoO_4 is a promising scheelite low-temperature co-fired ceramic (LTCC) and also an excellent luminescent material.