Growth, optical, thermal, dielectric and microhardness characterizations of melaminium bis (trifluoroacetate) trihydrate single crystal

Single crystals of melaminium bis (trifluoroacetate) trihydrate (MTFA) of dimensions (8 x 8 x 4 mm(3)) have been grown successfully by slow evaporation technique. The unit cell dimensions and morphology have been identified from X-ray powder diffraction analysis. The UV absorption edge is found to be 345 nm with a wide optical transmittance window covering the visible region and the direct optical band gap is calculated as 4.59 eV. The various optical properties such as reflectance, extinction coefficient, refractive index, optical conductivity have been calculated and their dependence with incident photon energy has also been discussed. Further, the thermal stability has been investigated by TG/DTA techniques. Microhardness measurements along three different planes show that there exists considerable anisotropy. The dielectric response of the crystal has been analyzed in the frequency range from 50 Hz to 5 MHz at different temperatures and the results are discussed. (C) 2013 Elsevier B.V. All rights reserved.