Novel Evaporation Process for Deposition of Kesterite Thin Films Synthesized by Solvothermal Method

Kesterite, a quaternary compound of Cu2ZnSnS4, is a promising option as a material absorber to reduce the cost of photovoltaic solar cells. The solvothermal method is a way to synthesize nanoparticles of this material. In this work, once synthesized, particles were deposited on a substrate through evaporation, and their morphological, structural, and optical properties were studied. Results show that changes of precursor ratios during solvothermal synthesis result in a modification of particle morphology but not on its size. The deposition of already synthesized kesterite through evaporation preserves kesterite structure and permits the formation of a homogenous film on a substrate. Optical reflectance and transmittance measurements allowed estimating the band-gap energy between 1.41 and 1.46 eV for representative samples, which is near the optimum for the absorber material

Sintering in a graphite powder bed of alumina-toughened zirconia/carbon nanotube composites: a novel way to delay hydrothermal degradation

Zirconia-based ceramics have been introduced in biomedical applications, for example, in hip implants. Certain zirconia composites are prone to spontaneously transform from the tetragonal phase to the monoclinic phase during long-term storage in the presence of moisture at low temperatures. This phenomenon is time-dependent and can be accelerated by water or water vapour. Herein, we report strong experimental evidence of a delayed t → m ZrO2 phase transformation in alumina-toughened zirconia (ATZ) and ATZ/multi-walled carbon nanotube (MWCNT) composites when pressureless sintered in air in a graphite powder bed. The m-ZrO2 phase in ATZ and ATZ/MWCNT composites sintered in a graphite powder bed after hydrothermal ageing for 20 h at 134 °C decreased by 81% and 87%, respectively, compared to an ATZ sample sintered in an alumina powder bed. The enhanced hydrothermal stability could be attributed to the formation of a thin continuous alumina protective layer covering the surface of the ceramic composites.publisher: Elsevier articletitle: Sintering in a graphite powder bed of alumina-toughened zirconia/carbon nanotube composites: a novel way to delay hydrothermal degradation journaltitle: Ceramics International articlelink: http://dx.doi.org/10.1016/j.ceramint.2014.11.155 content_type: article copyright: Copyright © 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.status: publishe