• Kalarical Janardhanan Sreeram

Articles written in Journal of Chemical Sciences

• Effective synthesis route for red-brown pigments based on Ce - Pr - Fe - O and their potential application for near infrared reflective surface coating

New cerium-based ceramic pigments, displaying Ce2Pr0.2Fe$_x$O$_{4.3+y}$ stoichiometry, were obtained at low temperature using a sol-gel method. The powder precursor dissolved in 80% ethylene glycol was precipitated using ammonia and the obtained gel calcined at 800°C for 2 h to yield homogeneous and crystalline particles with a diameter of around 150 nm. The oxide was composed of cerium in its +4 oxidation state and Pr in its +3 oxidation state. The oxides with varying Fe content had an intense red-brown colour, with bandgap energy of around 2.2 eV at 0.1 mol% Fe doping. The near infra red reflectance from these pigments, a measure of their ability to reflect rather than absorb heat waves from sunlight was found to be 82.7%, even in the absence of a white reflective base. Such high near infra red reflectance from these pigments qualify them for being ideal cool pigments for surface coating applications.

• Frequency upconversion in catechin assisted LaF₃: Yb³⁺-Er³⁺ square nanoplates

Yb ³⁺ -Er³⁺ codoped lanthanum upconverting nanostructures with varying concentration of dopants have been synthesized by catechin method. The prepared upconverting nanostructures were characterized through XRD,TEM,XPS, NIR absorption,TGAandDSCanalysis.TEMstudy confirms the formation of squareshaped nanoplates with size less than 100 nm. XPS peaks around 830–854eV further reveal the formation of LaF ₃ in the prepared samples. Frequency upconversion spectra from the developed nanostructures corresponding to the ²H₁₁/₂, ⁴S₃/₂ → ⁴ I₁₅/₂ and ⁴F₉/₂ → ⁴I₁₅/₂ transitions upon 980nm excitation are reported. Enhancement in the upconversion emission of catechin-based lanthanum nanostructures has been observed when compared with that prepared by ammonium di-n-octadecyldithiophosphate (AODTP) method.

• # Journal of Chemical Sciences

Volume 132, 2019
All articles
Continuous Article Publishing mode

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019