New NiAs-Type solid solutions Cr1-xTixSe (x= 0-0.15): Structural and physical characterization

J. P. BOLLETTA; J. M. DE PAOLI; G. TIRAO; R. D. SANCHEZ; R. E. CARBONIO

Merida

Congreso; II Reunión de la Asociación Latinoamericana de Cristalografía; 2016

LACA

The novel Cr1-xTixSe compounds have been synthesized for x = 0, 0.05, 0.10 and 0.15. Although both CrSe and TiSe are individually reported as nickel arsenide (NiAs) structure type phases [1, 2], solid solutions in this system have not been previously sinthesized. Inspired by a similar system containing vanadium instead of titanium [3], we set to discover new related solid solutions.The mentioned compounds were synthesized by heating stoichiometric mixtures of the pure elements inside evacuated quartz ampoules at different times and temperatures depending on composition. Structural characterization was made using Powder X-Ray Diffraction data. All samples belong to the P63/mmc space group and share a NiAs-type structure, with slight changes on cell parameters for each composition (from a = 3.684 Å and c = 6.024 Å for CrSe to a = 3.668 Å and c = 6.040 Å for Cr0.85Ti0.15Se).Chromium and titanium are known to have different oxidation states in selenide compounds, both varying between +2 and +4. X-ray Emission Spectroscopy (XES) measurements were carried out in order to study the oxidation state of chromium in these new compounds. By comparing peak positions in high-resolution Kβ XES spectra of chromium selenides and the corresponding peaks in appropriate standards, oxidation states can be inferred for each sample [4]. All three substituted samples contain chromium in an average +1.9 ± 0.2 oxidation state.Additional physical characterization includes resistivity measurements carried out between 80 and 300 K. Samples show a metallic behaviour respect to temperature change. The results of these measurements indicate an overall decrease in resistivity with the addition of titanium in comparison with CrSe. These results and its conclusions will be further discussed.In conclusion, we were able to obtain the desired solid solutions. All samples belong to the expected space group and share a structure type. Oxidation states were assessed by XES and resistivity measurements were performed and analysed. Further studies are required to continue probing the properties of these new solid solutions.