ORIGINAL PAPER Substitution effects on the bulk and surface properties of (Li,Ni) Mn 2 O 4 D. Alburquenque 1 & J. C. Denardin 2 & L. Troncoso 3 & J. F. Marco 4 & J. L. Gautier 1 Received: 9 April 2017 /Revised: 9 August 2017 /Accepted: 26 August 2017 # Springer-Verlag GmbH Germany 2017 Abstract Manganese oxides of spinel structure, LiMn 2 O 4 , Li 1-x Ni x Mn 2 O 4 (0.25 ≤ x≤ 0.75), and NiMn 2 O 4 , were studied by EDS, XRD, SEM, magnetic (M-H, M-T), and XPS mea- surements. The samples were synthesized by an ultrasound- assisted sol-gel method. EDS analysis showed good agree- ment with the formulations of the oxides. XRD and Rietveld refinement of X-ray data indicate that all samples crystallize in the Fd3m space group characteristic of the cubic spinel struc- ture. The a-cell parameter ranges from a = 8.2276 Å (x = 0) to a = 8.3980 Å (x = 1). SEM results showed particle agglomer- ates ranging in size from 2.3 μm(x = 0) down to 0.8 μm (x = 1). Hysteresis magnetization vs. applied field curves in the 5–300K range was recorded. ZFC-FC measurements indi- cate the presence of two magnetic paramagnetic-ferrimagnetic transitions. The experimental Curie constant was found to vary from 5 to 7.1 cm 3 K mol -1 for the range of compositions studied (0 ≤ x ≤ 1). XPS studies of these oxides revealed the presence of Ni 2+ , Mn 3+ , and Mn 4+ . The experimental Ni/Mn atomic ratios obtained by XPS were in good agreement with the nominal values. A linear relationship of the average oxi- dation state of Mn with Ni content was observed. The oxide’ s cation distributions as a function of Ni content from x =0 Li + [Mn 3+ Mn 4+ ]O 4 to x = 1 Ni 2þ 0:35 Mn 3þ 0:65 Ni 2þ 0:65 Â Mn 3þ 1:35 Ã O 4 were proposed. Keywords XRD . Spinels . Mixed oxides . XPS . Magnetic properties Introduction Spinel materials based on 3D transition metals, in particular Mn, are commonly studied because of their outstanding semi- conducting properties and their application to multiple fields, which include, among others, temperature sensors, thermis- tors, magnetic field sensors, magneto-resistance devices, chemical catalysts, electrocatalysts, and power source cath- odes. A class within these materials concerns the lithium- based batteries because of their great potential focused on low-cost energy storage, high-voltage cathode, and long life [1–3]. The performance of these batteries depends strongly on the purity of the materials used because these materials are insertion compounds implying the existence of paths for the Li + ions. Besides this, the electrical transport mechanisms are sensitive to the ability of the cations to occupy different sites in the structure, thus modifying the mechanisms of electrical transport. Novel chemical methods for metallic oxide preparation have been used for several years as an alternative to traditional solid-state reaction routes, the latter invariably producing unreactive, inhomogeneous samples with undesirable second- ary phases and large grains. The use of nanostructured mate- rials has opened new opportunities in different areas such as catalysis, energy production, and storage. In this context, syn- thetic methods assisted by high-intensity ultrasound irradia- tion (20 kHz–10 MHz) have been described as promising * J. L. Gautier juan.gautier@usach.cl 1 Departamento de Química de los Materiales, USACH, Av. Libertador Bernardo O’Higgins 3363, 9170022 Santiago, Chile 2 Departamento de Física, USACH, Av. Ecuador 3469, 9170124 Santiago, Chile 3 Instituto de Materiales y Procesos Termomecánicos, UACH, Gral. Lagos 2086, 5111187 Valdivia, Chile 4 Instituto de Química Física BRocasolano^, CSIC, Serrano 119, 28006 Madrid, Spain Ionics DOI 10.1007/s11581-017-2266-8