New Cr1-xTixSe solid solutions with NiAs-type structure: X-Ray powder diffraction and emission spectroscopy studies

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

Petropolis

Congreso; XV Latin American Seminar of Analysis by X-Ray Techniques (SARX 2016); 2016

SARX

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 NiAs-type phases, solid solutions in this system have not been previously synthesized. Structural characterization was made using X-Ray Powder Diffraction (XRD) data. All samples belong to the P63/mmc space group and share the nickel arsenide (NiAs) structure type. Chromium and titanium are known to have different oxidation states in selenide compounds, both varying between +2 and +4 oxidation states. In the case of study stoichiometry suggests a +2 oxidation state for the metals. However, the NiAs structure presents a very short cation-cation distance that can lead to some degree of bonding, affecting oxidation states. X-ray Emission Spectroscopy (XES) measurements were carried out in order to study the oxidation state of chromium in these new compounds. A high-resolution Kβ spectrum of a common chromium selenide is shown in Figure 1. By calculating the difference between the Kβ5and Kβ1,3 peak positions (DE) and comparing with appropriate standards, oxidation states can be inferred for each sample. All three substituted samples contain chromium in an average +2 oxidation state within experimental error. Additional sample characterization included resistivity measurements, which will also be discussed and complemented by the conclusions of the structural characterization as a whole.