The structural stability and physical properties of NdSrNi1 − x Co x O4 ± δ (0.1 ≤ x ≤ 0.9) mixed oxides, elaborated by conventional sol–gel process, have been investigated and obtained results show that substitution of nickel by cobalt at x = 0.5 enhances conductivity at room temperature; σ = 17.24 Ω−1 cm−1 coinciding with minimum activation energy (E a = 0.05 eV). Rietveld refinements of X-ray powder diffraction patterns at room temperature indicate that all compositions crystallize in a tetragonal system with I4/mmm space group and exhibit K2NiF4-type structure. Variations of a and c parameters display various behavior with increasing cobalt content. Changes in cell parameters are discussed in terms of crystal field theory. In addition, transition metal oxidation state is investigated on the basis of the Brown bond valence calculation. The deduced Global Instability Index (GII) value decreases when cobalt substance increases, indicating that the structure becomes more stable once cobalt is introduced. Oxygen stoichiometry of these compounds was determined from thermogravimetric analyses (TGA) followed by reduction in 5% H2 in N2 gas. Conductivity of NdSrNi1 − x Co x O4 ± δ (0.1 ≤ x ≤ 0.9) oxides was measured by an ac four-probe method. Oxygen vacancies are the possible ionic charge carriers. Specimens exhibit a semiconducting behavior in the whole range of temperature. The electrical transport mechanism agrees with an adiabatic small polaron hopping (ASPH) model.
Ionics – Springer Journals
Published: Jun 15, 2017
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera