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The synthesis of group IV transition metals (TMs) such as Ti, Zr, and Hf from their respective oxides (TMO 2) poses significant challenges with current methods. There is an urgent need for an environmentally friendly and versatile approach to establish sustainable, efficient, and adaptable TM synthesis technology from TMO 2. In this study, the LN process (Lee-Nersisyan), a novel and straightforward approach that employs CaMg 2 as the reductant for TMO 2 powders is introduced. This innovative strategy involves the thermal processing of TMO 2 + k CaMg 2 mixtures (with k values ranging from 2 to 5 moles) in an argon atmosphere at temperatures between 800 and 1200 °C. The process yields high-purity TM powder with particle sizes in the range of 5–25 μm and oxygen content of less than 0.2 wt%. We apply density-functional theory (DFT) to elucidate the interaction energies and equilibrium interatomic distances between Ti-Ca, Ti-Mg, Ca-Mg, Mg-Mg, Ca-Ca, and Ti-Ti metallic pairs. Additionally, we discuss the growth behavior of TM particles through molecular dynamics simulation (MD) employing LAMMPS. Our LN process represents a promising solution for efficient and sustainable TM synthesis from TMO 2. • An innovative method for producing TM (Ti, Zr, Hf) powders from oxides is presented. • Utilizing CaMg 2 as reductant results TM particles with 0.2 wt% of oxygen is obtained. • Calciothermic reduction of TMO 2 is found to be the primary driving force of reaction. • The interaction energies and interatomic distances of M-M pairs are calculated by DFT. • TM particles sintering and growth behavior based on MD simulation is highlighted. [ABSTRACT FROM AUTHOR]

Ternary carbides R 2 Ni 5 C 3 (R = La-Nd, Sm, Gd, Tb) are the only representatives of the family of interstitial carbides (i.e., compounds with the composition R x T y C z , where T is a transition metal and 2 ≤ (x + y)/ z ≤ 4). The crystal structures (space group P 4 /mbm) of Sm 2 Ni 5 C 3 [ a = 8.26131(7) Å, c = 3.89090(4) Å, R B = 3.2 %, R p = 1.3 %] and Gd 2 Ni 5 C 3 [ a = 8.24683(4) Å, c = 3.85398(2) Å, R B = 3.9 %, R p = 3.6 %] are refined for the first time. They are considered to be built by distorted [ R 8 ]-cubes incorporating [CNi 6 ]-octahedra condensed with [C 2 R 8 ]-trigonal bi-prisms. The structural units are characteristic of the CaTiO 3 - and AlB 2 -prototypes, respectively. Temperature dependencies of the magnetic susceptibility, specific heat, electrical resistivity, thermal conductivity, and thermopower in the range 1.8 K (2 K) – 300 K are studied. R 2 Ni 5 C 3 with R = Nd, Sm, Gd, order antiferromagnetically at T N = 3.4, 6.6, and 22.2 K, respectively. The nature of magnetic transitions in Ce 2 Ni 5 C 3 at T mag = 2.3 K and Tb 2 Ni 5 C 3 at 29.4 K requires further clarification. No magnetic orderings for La 2 Ni 5 C 3 (Pauli paramagnetic) and Pr 2 Ni 5 C 3 (Curie-Weiss/van Vleck paramagnetic) are detected. Relatively high electrical resistivities and thermal conductivities, together with the small absolute values of Seebeck coefficients, result in poor thermoelectric performance of the R 2 Ni 5 C 3 carbides. The calculated electronic structure for La 2 Ni 5 C 3 indicated a rather low density of states at the Fermi level as well as its extreme sensitivity to any doping. The stabilization of the R 2 Ni 5 C 3 interstitial carbides up to R = Tb is discussed assuming the rigid-band approach as well as the analysis of selected Ni-C interatomic distances. • The only family interstitial carbides R 2 Ni 5 C 3 (R = La-Nd, Sm, Gd, Tb) are atomic-size- and electronically-stabilized systems. • R 2 Ni 5 C 3 with R = Nd, Sm, Gd order antiferromagnetically, R = La is Pauli paramagnetic, R = Pr – Curie-Weiss/Van Vleck paramagnetic; nature of magnetic ordering for R = Ce, Tb is unclear. • R 2 Ni 5 C 3 are metals with high electrical resistivities and thermal conductivities, and low Seebeck coefficients. [ABSTRACT FROM AUTHOR]

Approaching the border of the first order transition and second order transition is significant to optimize the giant magnetocaloric materials performance. The influence of vanadium substitution in the Mn 1.2- x V x Fe 0.75 P 0.5 Si 0.5 alloys is investigated for annealing temperatures of 1323, 1373 and 1423 K. By tuning both the annealing temperature and the V substitution simultaneously, the magnetocaloric effect can be enhanced without enlarging the thermal hysteresis near the border of the first to second order transition. Neutron diffraction measurements reveal the changes of site occupation and interatomic distances caused by varying the annealing temperature and V substitution. The properties of the alloy with x = 0.02 annealed at 1323 K is comparable to those found for the MnFe 0.95 P 0.595 Si 0.33 B 0.075 alloy, illustrating that Mn 1.2- x V x Fe 0.75 P 0.5 Si 0.5 alloys are excellent materials for magnetic heat-pumping near room temperature. • Low field performance can be enhanced without enlarging the thermal hysteresis. • V prefers to occupy 3 f site and shortens the intra-atomic distances. • Decreasing effect of V on T C is stronger at lower annealing temperature. • An increased Δ T ad of 2.7 K and a decreased hysteresis of 1.8 K at 1 T are achieved. [ABSTRACT FROM AUTHOR]

Novel ternary intermetallic phase Ce 2 RuGe was synthesized via arc-melting of the constituents and subsequent annealing at 700°С. Its crystal structure was determined from the powder X-ray diffraction data collected at room temperature. The compound crystallizes in the orthorhombic structure of a new type: space group Pmmn (No. 59), lattice parameters: a = 4.38235(5) Å, b = 4.31818(5) Å, c = 9.91496(15) Å, Z = 2, Pearson symbol oP 8. In the fully ordered unit cell of Ce 2 RuGe, there are two crystallographic positions for Ce atoms, single site with Ru atoms, and single site with Ge atoms, each with the multiplicity of two. The crystal structure is built of infinite zigzag-like chains of the Ru and Ge atoms, propagating along the [010] direction. The essential feature is a very short interatomic distance between the Ce1 atoms and the Ru atoms being equal to 2.226(2) Å, while the Ce2–Ru distance is of regular length. This structural property gives rise to distinctive physical behavior of the compound that exhibits the coexistence of valence fluctuations associated with unstable 4 f shell of the Ce1 ions and a long-range magnetic ordering that emerges in the Ce2 ions sublattice. As revealed by means of magnetization, heat capacity and electrical resistivity measurements, Ce 2 RuGe orders antiferromagnetically at T N = 12.0(1) K, and becomes ferromagnetic below T C = 8.5(3) K. • The novel ternary germanide Ce 2 RuGe crystallizes with its own structure type. • Some Ce–Ru distances in the unit cell are unusually short (2.226(2) Å). • The compound exhibits coexistence of magnetic ordering and valence fluctuations. • Ce 2 RuGe orders antiferromagnetically, yet becomes ferromagnetic at lower temperatures. [ABSTRACT FROM AUTHOR]

Abstract In this work, we investigate the stabilities of H, B, C, N, O, and Zr atoms at various interstitial sites in hcp-Zr using a first-principles theoretical approach. The formation energy of each interstitial atom at each site in the hcp crystal was determined, and the difference in the energy at different sites were considered as a static energy barrier to predict energetically favored diffusion pathways. Linear and non-linear prediction models for the interstitial formation energy were developed using readily accessible chemical and structural input parameters. We show that a simple linear model predicts the formation energies of the interstitial atoms with an R2 of 97%. Graphical abstract Image 1 Highlights • Formation energies (E f) of H, B, C, N, O and Zr impurity atoms at various interstitial sites of hcp-Zr were determined. • The most preferable diffusion path for each atom was predicted by considering the difference of E f at different sites. • Simple linear and non-linear prediction models for E f were proposed. • A linear model with four readily accessible input parameters predicts E f with R2 of 97%. • The key input parameters for E f : electronegativity, valence electrons, the interatomic distance, interstitial symmetricity. [ABSTRACT FROM AUTHOR]

Pt-modified β -NiAl is an alloy of special interest for bond coatings in the hot sections of the engines. Nevertheless, the site occupancy of Pt is still an open issue. In this work, we have constructed a Ni-Al-Pt interatomic potential and carried out the molecular dynamics simulations to reveal the atomic structures and displacement behaviours of Pt in B 2-NiAl. The results of the simulations not only show that the Pt atoms have a strong preference for the Ni site in B 2-NiAl but also suggest that an increasing Pt concentration leads to a more pronounced displacement of the Al atoms. Moreover, the simulations predict the occurrence of phase separation in B 2-NiAl when the Pt concentration reaches 20%, which is confirmed in the subsequent experiments by the formation of a β -NiAl+Al 2 Pt dual-phase structure. The present findings promote the understanding of the atomic structures in B 2-NiAl, which in turn may provide useful guidance for the fabrication of high-quality β -NiAl bond coatings. [ABSTRACT FROM AUTHOR]

Based on the experimental data and first-principle calculations, the newly constructed long-range empirical potential was first developed for the Ni-Hf-Mo system. Taking the realistic interatomic potential as the starting point, the atomic-level structure and its correlation with the shear deformation process of the Ni-Hf-Mo metallic glasses were investigated and characterized by atomic simulations and various analysis methods. Interestingly, the appropriate amount of Mo addition to Ni-Hf alloys could enhance the intrinsic strength, while reducing the plasticity. By monitoring atomic-scale structure during the shear deformation, local shear behaviors are closely correlated with the structural and mechanical response. In addition, the connectivity degree of the spatial network could have a considerable effect on the structure and performance of metallic glasses. [ABSTRACT FROM AUTHOR]

The temperature-dependent atomic structural evolution of a Zr 64.13 Cu 15.75 Ni 10.12 Al 10 metallic glass is studied by in-situ high-energy X-ray diffraction in the temperature range of 79–553 K. The interatomic distance in the first nearest neighbor shell increases with decreasing temperature, while the interatomic distance in other atomic shells decreases. This decrease in the interatomic distances causes volume shrinkage and an increase in the strength of the metallic glass. The volume shrinkage can be quantitatively described by the Varshni function. The structural information is helpful for deeply understanding of the origin of the rejuvenation of metallic glasses at the cryogenic temperatures. [ABSTRACT FROM AUTHOR]

High refractive glasses in the La 2 O 3 –Nb 2 O 5 –B 2 O 3 (LNB) system were synthesized by the melt-quenching technique and correlations between their compositions and structural features were clarified. It was found that the refraction index of the LNB glasses is tunable from 1.71 to 1.98 by the variation of the Nb 2 O 5 fraction from 5 to 30 mol%. The infrared spectroscopy analysis implies on the presence of three and four coordinated borate units, as well as six coordinated niobium atoms. The X-ray absorption (La L 3 -edge and Nb K-edge XANES and EXAFS) spectroscopy and total X-ray scattering results show that niobium atoms maintain octahedral oxygen coordination despite the wide variation of the Nb 2 O 5 content, while average lanthanum coordination number is versatile and changes from ~8 to ~10. The interatomic distance values testify that the niobium octahedra in the glass network are connected only "by corners". The stability of niobium local atomic structure implies that the main source of the changes in the optical properties of studied glasses is the variation of the Nb 2 O 5 content. The deeper understanding of the local atomic structure of the high refractive index LNB glasses paves ways for the development of new glass wafers for cutting-edge augmented reality devices. [Display omitted] • High refractive index Nb 2 O 5 –La 2 O 3 –B 2 O 3 glasses derived by the melt-quenched technique. • Local atomic structure of Nb and La studied by the X-ray synchrotron techniques. • Nb atomic structure weakly depends on the concentration of Nb 2 O 5. • Nb octahedra connected "by corners" in the glass network. • Local atomic structure of La is sensitive to the concentration of Nb 2 O 5. [ABSTRACT FROM AUTHOR]

For the first time by X-ray method two phases of the solid solutions LaCo x Ga 1−1.2 x Mg 0.2 x O 3− δ and LaCo x Ga 1−1.5 x Mg 0.5 x O 3− δ ( x = 0.01–0.10) with different structure were found – rhombohedral and orthorhombic phases. On the basis of the data on evaporation of the components a synthetic procedure was advanced allowing the losses of cobalt to be minimized. The study of magnetic characteristics of obtained solid solutions showed the formation of high nuclearity clusters containing cobalt atoms, and also magnesium and associated vacancies even in diluted solid solutions. Clusters are characterized by a competition between ferro- and antiferromagnetic exchange interactions, whereas the long order exchange is antiferromagnetic. [ABSTRACT FROM AUTHOR]

The synchrotron radiation X-ray absorption fine structure (XAFS) technique is used to study the local structure of the key atom Ru in a series of Ni-Al-Ru ternary alloys with different Ru contents and heat treatments. All the investigated alloys consist of two phases, γ and γ', and especially Ru exists as an atom coordinated by 12 Ni atoms in the first shell without Ru clusters or intermetallic compounds. In γ phase Ru resides on the Ni lattice site introducing an outward relaxation of the neighboring atoms, while in the γ' phase Ru replaces the Al lattice site causing an inward relaxation. The interatomic distance of Ru–Ni bond and Debye-Waller factor are mainly affected by the composition and increase with the increasing Ru content. While the effect of heat treatment is obvious when the Ru content is higher than 6 at%. The variation of Ru local atomic structure can greatly influence the microstructural evaluation and deformation mechanism by changing the lattice misfit and the vacancy formation energy to control the creep properties of Ni-Ru-Al ternary alloys. [Display omitted] • The local atomic structure of Ru has been studied by synchrotron radiation XAFS. • Ru exists as an atom and no Ru clusters or intermetallic compounds are found. • The local atomic structure of Ru is mainly affected by the composition. [ABSTRACT FROM AUTHOR]

• Ce 2 Fe 17 -based alloys were investigated by experiments and first-principles calculations. • Si/Nd addition increase c / a and d Fe6c-6c values and contributes to an enhanced T C. • Si substitution decreases the E form of 2:17R phase by hybridizing with Fe atoms. • High Δ S M , wide Δ T FWHM and high RCP were obtained for Ce 1.6 Nd 0.4 Fe 17−x Si x magnetocaloric refrigerants. The electronic structures and magnetocaloric properties of Ce 2 Fe 17 -based materials doped with Nd/Si have been investigated by means of experiments and first-principles calculations based on density functional theory (DFT). Ce 1.6 Nd 0.4 Fe 17−x Si x alloys crystallize in a rhombohedral Th 2 Zn 17 -type 2:17R main structure with trace amounts of the α-Fe secondary phase, and Si substitution for Fe contributes to the 2:17R phase. Compared with the parent Ce 2 Fe 17 compound, Nd/Si substitution increases the Curie temperature (T C) to 273 K for Ce 1.6 Nd 0.4 Fe 17 and to 297 K for Ce 1.6 Nd 0.4 Fe 16.67 Si 0.33. DFT calculations reveal that Nd/Si addition increases the c/a values and Fe-Fe interatomic distances at the 6c site, thus leading to an enhanced T C. In addition, Si atoms in Ce 2 Fe 17 -based alloys energetically prefer to occupy the 18h site. The local density of states and charge density difference map for a single Si and its first-nearest-neighbor Fe atoms confirm a strong hybridization between the electronic orbitals of Si and Fe atoms, leading to slight lattice contraction and a decrease in the formation energy of the 2:17R phase. The Ce 1.6 Nd 0.4 Fe 17−x Si x alloys exhibit a maximum isothermal magnetic entropy change ( Δ S M ) of 3.7–4.1 J/kg K, working temperature range (∆ T FWHM) of 90.5–95.5 K, and a relative cooling power (RCP) of 350–371 J/kg at μ 0 ∆ H = 5 T, suggesting that Nd/Si substitution contributes to the optimization of Ce 2 Fe 17 -based alloys as potential room-temperature magnetic refrigerants. [ABSTRACT FROM AUTHOR]

• Solid solution mechanism of Na3LiTi5O12 (NTO) during charging/discharging was confirmed. • Na ions at 8a site in NTO gradually shift to 16c site with increasing SOC. • Topological analysis revealed that Na ions at 8a site stable with one other Na at adjacent 16site. [Display omitted] The reaction mechanism of a spinel-type sodium titanium oxide (Na 3 LiTi 5 O 12) was investigated using in situ XRD during the Na insertion/extraction process. The XRD profiles gradually shifted to lower and higher angles during the sodiation and de-sodiation processes, respectively, while maintaining a spinel-type structure and no new peaks were observed, indicating a solid-solution reaction according to the following reaction; (Na) 3 8 a (Li 1 Ti 5)16 d O 12 192 i + 3Na+ + 3e− ↔ (Na) 6 16 c (Li 1 Ti 5)16d O 12 192 i. The evolution of the XRD profile was confirmed to be highly reversible, which explains the high cycling stability of the NTO electrode. There are two possible sites for Na to occupy: 8 a and 16 c. The Na ion initially occupies only the 8 a site, as confirmed by the 220 peak. The intensity of the 220 peak gradually decreased with increasing SOC and was hardly detected at an SOC of 50%, indicating that all the Na ions at the 8 a sites moved to the 16 c sites. Topological analysis combined with XRD revealed that the Na ion at the 8 a site is stable with one other Na ion at an adjacent 16 c site despite the interatomic distance being too short. [ABSTRACT FROM AUTHOR]

• Multitemperature X-ray study revealed a structural phase transition in HT-Ce 2 Rh 2 Ga. • Phase transition is accompanied by non-merohedral twinning. • Phase transition is reversible with a small hysteresis. • Interatomic distances abnormally increase when the sample is cooled below 145 K. • A strong NTE in the 85–112 K range with α = −2.588 10−4 deg−1 is found. A recently investigated HT-Ce 2 Rh 2 Ga was found to exhibit a magnetic phase transition at 128.5 K. A comprehensive multi-temperature investigation in the 85–400 K temperature range showed that the compound undergoes a structural phase transition as well. Upon cooling below 123.2 K its crystal symmetry changes from Cmce to C 2/ m being accompanied by non-merohedral twinning. Both structural transformations are reversible with a small hysteresis furthermore. The temperature of the structural phase transition was detected by anomalies in temperature dependences of unit cell dimensions, interatomic distances, and atomic displacement parameters. Negative thermal expansion along the c -axis was revealed in the range 92.7–170 K. When cooled to 200 K, Ce and Rh atoms converge to a distance sufficient for structural changes to become qualitative. Upon further cooling to 145 K, this interaction affects positions of all the atoms in the structure, leading to anisotropy of earlier equivalent interatomic distances and a sharp anomalous increase in atomic displacement parameters, the dynamics of which deviates more and more from the theoretical dependences in the Einstein and Debye approximations. [ABSTRACT FROM AUTHOR]

The structure and basic properties of a hexagonal polymorph of GdAlO 3 aluminate (GAH) were studied using a set of experimental methods (XRD, FTIR, Raman spectroscopy, diffuse reflectance spectroscopy, luminescence spectroscopy, magnetic susceptibility, and TEM). The GAH crystallized at 900 °C from an amorphous precursor and decomposed into perovskite GdAlO 3 (GAP) at 1000 °C. XRD pattern of polycrystalline GAH could be indexed in P 6 3 /mmc space group with unit cell parameters a = 0.3734 nm, c = 1.0535 nm, following literature data. The electron diffraction revealed, however, the presence of well-defined superstructure reflections due to defects ordering. Contrary to a recent report suggesting the presence of CO 3 groups in the structure of similar hexagonal YAlO 3 , we did not observe such groups in the FTIR spectra of GAH. On the other hand, the stoichiometry of GAH differs from ideal GdAlO 3 , with Al/Gd atomic ratio close to 1.2, similar to reported for hexagonal YAlO 3. GAH exhibits paramagnetic behavior over 1.8–300 K temperature range, with the effective Gd magnetic moment μ eff = 7.90 μ B , close to the theoretical value for free Gd3+ ion. No paramagnetic – antiferromagnetic phase transition at ~4 K, characteristic for perovskite-type GdAlO 3, was observed. The reason is probably a less "dense" structure of GAH, with longer Gd-Gd and Gd-O-Gd interatomic distances. Emission spectra of Dy doped (~1 at%) GAH and GAP revealed dramatic differences in Dy3+ emission bands, despite similar mean crystallite size of the host material. An almost structureless 4F 9/2 →6H 13/2 and 4F 9/2 →6H 15/2 emission bands, observed for GAH, indicate, following TEM data, that Dy ions occupy numerous nonequivalent sites due to the presence of a large concentration of crystal defects. ga1 • Hexagonal polymorph of GdAlO 3 (GAH) was synthesized and characterized. • Electron diffraction revealed superstructure reflections in GAH due to defects ordering. • GAH transforms into perovskite GdAlO3 (GAP) at 1000 °C. • Contrary to GAP, GAH does not show magnetic ordering at low temperature. • TEM and Dy luminescence indicate strong structure disorder in GAH. [ABSTRACT FROM AUTHOR]

Magnetic cooling is one of the modern eco-friendly technologies, the development of which requires a search for novel functional materials. Gd-based metallic glasses are of promising candidates to be solid-state refrigerants, while their magnetic properties are still far from optimal. Recent studies reveal that the magnetocaloric characteristics of these alloys are correlated with their glass-forming ability (GFA). The partial replacement of the alloy components by elements that are chemically similar but strongly dissimilar in radii seems to be a very perspective way to improve GFA. This study is intended to prove how atomic size misfit influences on glass-formation, structure, and magnetic properties of Gd-based alloys on the example of Gd-Sc-Co-Ni-Al system. By gradually replacing Gd by Sc and Co by Ni, we have fabricated a series of completely glassy alloys and examine their structure, thermal characteristics, magnetic and magnetocaloric properties. We perform ab initio molecular dynamics simulations of the melts, which suggest that GFA of the alloys is mainly due to the high diversity of interatomic bond lengths. On the microscopic level, the main effect of the element substitution is the shortening of interparticle distances between rare-earths and transition metals because of strong chemical interaction. • Novel Gd-Sc-Co-Ni-Al BMGs with exceptional GFA are fabricated. • Arc-melted ingots of 10 mm in diameter exhibit a nearly fully amorphous structure. • The BMGs demonstrate an excellent relative cooling power. • A table-like behavior for magnetocaloric effect is revealed. • Ab initio simulation reveals high GFA is caused by diversity of interatomic distances. [ABSTRACT FROM AUTHOR]

Scanning tunneling microscopy (STM) technique is widely used to study the electronic and structural properties of nano structures. Here we study the atomic structure of a Ni–Nb BMG by means of ultra high vacuum (UHV) STM in local areas of nanometer scale size, and report the direct atomic structure observation supported by ab initio molecular dynamics (MD) and density functional theory (DFT) simulations used to understand the observed structural and electronic features. It was possible to resolve the atomic surface structure of a bulk metallic glassy sample while MD simulation explained relatively large interatomic distances observed using STM. • Bulk metallic glassy sample direct atomic structure observation. • Scanning tunneling microscopy in ultrahigh vacuum conditions. • Surface images observed by STM are reproduced by ab-initio MD. • Partial electron density of states explain the interactions. • Only Ni atoms are visible at the negative bias voltage. [ABSTRACT FROM AUTHOR]

The performance of lithium-ion batteries is very much affected by the temperature under which they are running due to changes in the properties of the battery components. By employing techniques of thermogravimetric analysis (TGA), X-ray diffraction (XRD) followed by Rietveld refinements, infrared spectroscopy and scanning electron microscopy (SEM), we show that the LiCoO 2 cathode material of a lithium-ion battery is specially affected in their composition and structural properties when the entire cathode (cathode material + current collector) was heat-treated from room temperature till 400 °C. After 250 °C, the starting electroactive cathode material, Li 0.94 CoO 2 , decomposes thermally in the Li 1 CoO 2 , Co 3 O 4 and O 2 reaction products, with their relative masses changing with the temperatures of heat treatments. Concomitantly, the treatments promoted changes in the lattice parameters of the pristine and decomposed cobalt oxides, as well as in the Li–O and Co–O interatomic distances, in the angles between the O–Co–O and O–Li–O bonds and in the intensity of infrared absorption of Co–O vibrational modes. Very surprisingly, all these parameters presented minimum or maximum values under the thermal treatment at 350 °C. This effect is believed to be related to the rate of Li 0.94 CoO 2 mass decomposition that reaches its maximum value at 335 °C, close to the temperature of 350 °C. The α, β and γ crystalline phases of the polyvinylidene difluoride (PVDF) binder and the agglomeration states of the cathode particles are as well affected by the thermal treatment performed. • Thermal decomposition of Li 0.94 CoO 2 cathode was followed up to 400 °C. • The crystalline phases Li 0.94 CoO 2 , Li 1 CoO 2 , Co 3 O 4 and carbon coexist. • Li 0.94 CoO 2 and Li 1 CoO 2 presented minima and maxima a and c lattice parameters at 350 °C. • Minima and maxima interatomic distances and angles in the Co–O and Li–O bonds were also observed at 350 °C. • Such structural changes resulted in a maximum infrared absorption at 350 °C for the Co–O bonds. [ABSTRACT FROM AUTHOR]