Intrinsic ferromagnetic properties in Cr-doped ZnO diluted magnetic semiconductors

The Cr-doped zinc oxide (Zn_1−xCr_xO, 0≤x≤0.08) diluted magnetic semiconductors have been synthesized successfully by the sol-gel method. Investigations on magnetic, optical and structural properties of the produced samples have been done. Energy dispersive spectroscopy (EDS) shows the existence of Cr ion in the Cr-doped ZnO. The results of X-ray diffraction (XRD), the transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) indicate that the Cr ions are at least partially substitutionally incorporated into the crystal lattice of ZnO. The produced samples show good high-T_c (Curie temperature) ferromagnetism (FM) in Cr-doped ZnO nanoparticles with Cr concentration of less than 5 at%. The results of photoluminescence (PL) further testify that FM is an intrinsic property of the Cr-doped ZnO nanoparticles. And the occurrence of FM should mainly contribute to the Cr doping.     

Synthesis and characterization of highly preferred orientation polycrystalline Co-doped ZnO thin films prepared by improved sol–gel method

Highly preferred orientation polycrystalline Zn_1?xCo_xO (x = 0, 0.03, 0.06, 0.09) thin films were prepared by improved sol–gel method on quartz glass substrates. The structural, optical and magnetic properties were investigated. The X-ray diffraction patterns show that all the samples have the same structure with one highly oriented c-axis (002) peak. None of the samples showed any signal of impurity phases. The c-axis lattice constant increased linearly with the increase in Co doping content, indicating that the doping of Co ions into the host lattice did not change the wurtzite structure of ZnO. UV–Vis transmittance spectroscopy showed that the average optical transmittance of the films is about 90 % in visible wavelength range. The optical band gap (Eg) decreased with increasing Co content. Also, the results of vibration sample magnetization ascertained the ferromagnetic behavior of Co-doped ZnO, having a Curie temperature higher than room temperature.     

Spin-glass like behavior in a new ternary uranium cobalt aluminide, U3Co4+xAl12−x with x=0.55(2)

The new compound U₃Co_4+xAl_12−x, where x=0.55(2), was prepared by arc-melting of the elemental components, followed by a prolonged annealing at elevated temperature. Scanning electron microscopy-energy-dispersive spectroscopy and powder X-ray diffraction were used to determine the deviation from the ideal stoichiometry. A small homogeneity range, that extends around the composition U₃Co_4+xAl_12−x with 0.4(1) ?x?0.7(1), could be detected. Single-crystal diffraction experiments revealed that U₃Co_4.55Al_11.45 crystallizes with the Gd₃Ru₄Al₁₂ type-structure, (space group P6₃/mmc, Z=2) in a cell of dimensions at room temperature, a=8.6518(2) Å, c=9.2620(2) Å. The crystal structure can be viewed as an intergrowth of two distinct layers of Co and Al atoms, and U, Al and mixed Al/Co atoms that pile up along the hexagonal axis. The results of the DC magnetization suggest the occurrence of a spin glass state at low temperature (T_f=8 K). The origin of freezing of the magnetic moments may arise from a topological frustration due to the location of the U atoms on the apexes of a distorted Kagomé lattice.     

Crystal structures and magnetic properties of two-dimensional antiferromagnets Co1−xZnxTeMoO6

Crystal structures and magnetic properties of metal telluromolybdates Co_1−xZn_xTeMoO₆ (x=0.0, 0.1,…,0.9) are reported. All the compounds have an orthorhombic structure with space group P2₁2₁2 and a charge configuration of M²⁺Te⁴⁺Mo⁶⁺O₆. In this structure, M ions form a pseudo-two-dimensional lattice in the ab plane. Their magnetic susceptibility measurements have been performed in the temperature range between 1.8 and 300 K. The end member CoTeMoO₆ shows a magnetic transition at 24.4 K. The transition temperature for solid solutions rapidly decreases with increasing x and this transition disappears between x=0.4 and 0.5, which is corresponding to the percolation limit for the square-planer lattice. From the magnetization, specific heat, and powder neutron diffraction measurements, it is found that the magnetic transition observed in the CoTeMoO₆ is a canted antiferromagnetic ordering of Co²⁺ ions. The antiferromagnetic component of the ordered magnetic moment (3.12(3)μ_B at 10 K) is along the b-axis. In addition, there exists a small ferromagnetic component (0.28(3)μ_B) along the a-axis.     

Enzyme mimics of spinel-type CoxNi1−xFe2O4 magnetic nanomaterial for eletroctrocatalytic oxidation of hydrogen peroxide

A series of spinel-type Co_xNi_1−xFe₂O₄ (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, 1.0) magnetic nanomaterials were solvothermally synthesized as enzyme mimics for the eletroctrocatalytic oxidation of H₂O₂. X-ray diffraction and scanning electron microscope were employed to characterize the composition, structure and morphology of the material. The electrochemical properties of spinel-type Co_xNi_1−xFe₂O₄ with different (Co/Ni) molar ratio toward H₂O₂ oxidation were investigated, and the results demonstrated that Co_0.5Ni_0.5Fe₂O₄ modified carbon paste electrode (Co_0.5Ni_0.5Fe₂O₄/CPE) possessed the best electrocatalytic activity for H₂O₂ oxidation. Under optimum conditions, the calibration curve for H₂O₂ determination on Co_0.5Ni_0.5Fe₂O₄/CPE was linear in a wide range of 1.0 × 10⁻⁸–1.0 × 10⁻³ M with low detection limit of 3.0 × 10⁻⁹ M (S/N = 3). The proposed Co_0.5Ni_0.5Fe₂O₄/CPE was also applied to the determination of H₂O₂ in commercial toothpastes with satisfactory results, indicating that Co_xNi_1−xFe₂O₄ is a promising hydrogen peroxidase mimics for the detection of H₂O₂.     

Consequence of doping mediated strain and the activation energy on the structural and optical properties of ZnO:Cr nanoparticles

We report on the sol-gel synthesis of Zn_1−xCr_xO (x=0.0, 0.05, 0.10, 0.15 and 0.20) nanoparticles. These nanoparticles were characterized by using thermogravimetry/differential scanning calorimetry (TG/DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman and Photoluminescence (PL). Electronegativity of Cr ions (Cr³⁺) reduces the final decomposition temperature by 40 °C and activation energy of the reaction when Cr is doped into ZnO. Doping of higher Cr concentration (x≥0.10) into ZnO shows formation of secondary spinel (ZnCr₂O₄) phase along with the hexagonal (ZnO) and is revealed by XRD. Formation of secondary phase changes the activation energy of the reaction and thus the strain in ZnO lattice. In Raman spectra, additional Raman modes have been observed for Zn_1−xCr_xO nanoparticles, which can be assigned to the modes generated due to Cr doping. The Cr doping into ZnO is also supported by PL, in which vacancies are formed with Cr ion incorporation and emission band shifts towards higher wavelength.     

Crystal chemistry of Co-doped Zn7Sb2O12

Zn₇Sb₂O₁₂ forms a full range of Co-containing α solid solutions, Zn_7−xCo_xSb₂O₁₂, with an inverse-spinel structure at high temperature. At low temperatures for x<2, the solid solutions transform into the low temperature β-polymorph. For x=0, the β→α transition occurs at 1225±25 °C; the transition temperature decreases with increasing x. At high x and low temperatures, α solid solutions are formed but are non-stoichiometric; the (Zn+Co):Sb ratio is >7:2 and the compensation for the deficiency in Sb is attributed to the partial oxidation of Co²⁺ to Co³⁺. From Rietveld refinements using ND data, Co occupies both octahedral and tetrahedral sites at intermediate values of x, but an octahedral preference attributed to crystal field stabilisation, causes the lattice parameter plot to deviate negatively from the Vegard's law. Sub-solidus compatibility relations in the ternary system ZnO-Sb₂O₅-CoO have been determined at 1100 °C for the compositions containing ?50% Sb₂O₅.     

Phase formation, crystal structures and magnetic properties of perovskite-type phases in the system La2Co1+z(MgxTi1−x)1−zO6

Perovskite-type cobaltates in the system La₂Co_1+z(Mg_xTi_1−x)_1−zO₆ were studied for z=0≤x≤0.6 and 0≤x<0.9, using X-ray and neutron powder diffraction, electron diffraction (ED), magnetic susceptibility measurements and X-ray absorption near-edge structure (XANES) spectroscopy. The samples were synthesised using the citrate route in air at 1350 °C. The space group symmetry of the structure changes from P2₁/n via Pbnm to R3¯c with both increasing Mg content and increasing Co content. The La₂Co(Mg_xTi_1−x)O₆ (z=0) compounds show anti-ferromagnetic couplings of the magnetic moments for the Co below 15 K for x=0, 0.1 and 0.2. XANES spectra show for the compositions 0≤x≤0.5 a linear decrease in the L₃/(L₃+L₂) Co-L_2,3 edge branching ratio with x, in agreement with a decrease of the average Co ion spin-state, from a high-spin to a lower-spin-state, with decreasing nominal Co²⁺ ion content.     

Magnetostructural correlations in the antiferromagnetic Co2−x Cux(OH)AsO4 (x=0 and 0.3) phases

The Co_2−xCu_x(OH)AsO₄ (x=0 and 0.3) compounds have been synthesized under mild hydrothermal conditions and characterized by X-ray single-crystal diffraction and spectroscopic data. The hydroxi-arsenate phases crystallize in the Pnnm orthorhombic space group with Z=4 and the unit-cell parameters are a=8.277(2) Å, b=8.559(2) Å, c=6.039(1) Å and a=8.316(1) Å, b=8.523(2) Å, c=6.047(1) Å for x=0 and 0.3, respectively. The crystal structure consists of a three-dimensional framework in which M(1)O₅-trigonal bipyramid dimers and M(2)O₆-octahedral chains (M=Co and Cu) are present. Co₂(OH)AsO₄ shows an anomalous three-dimensional antiferromagnetic ordering influenced by the magnetic field below 21 K within the presence of a ferromagnetic component below the ordering temperature. When Co²⁺ is partially substituted by Cu²⁺ions, Co_1.7Cu_0.3(OH)AsO₄, the ferromagnetic component observed in Co₂(OH)AsO₄ disappears and the antiferromagnetic order is maintained in the entire temperature range. Heat capacity measurements show an unusual magnetic field dependence of the antiferromagnetic transitions. This λ-type anomaly associated to the three-dimensional antiferromagnetic ordering grows with the magnetic field and becomes better defined as observed in the non-substituted phase. These results are attributed to the presence of the unpaired electron in the dx²−y² orbital and the absence of overlap between neighbour ions.     

Electron doping effect on structural and magnetic phase transitions in Sr2−xNdxFeMoO6 double perovskites

Polycrystalline Sr_2−xNd_xFeMoO₆ (x=0.0, 0.1, 0.2, 0.4) materials have been synthesized by a citrate co-precipitation method and studied by neutron powder diffraction (NPD) and magnetization measurements. Rietveld analysis of the temperature-dependent NPD data shows that the compounds (x=0.0, 0.1, 0.2) crystallize in the tetragonal symmetry in the range 10-400 K and converts to cubic symmetry above 450 K. The unit cell volume increases with increasing Nd³⁺ concentration, which is an electronic effect in order to change the valence state of the B-site cations. Antisite defects at the Fe-Mo sublattice increases with the Nd³⁺ doping. The Curie temperature was increased from 430 K for x=0 to 443 K for x=0.4. The magnetic moment of the Fe-site decreases while the Mo-site moment increases with electron doping. The antiferromagnetic arrangement causes the system to show a net ferrimagnetic moment.     

Structural, magnetic, and electrochemical studies on lithium insertion materials LiNi1−xCoxO2 with 0≤x≤0.25

The structural, magnetic, and electrochemical properties of the LiNi_1−xCo_xO₂ samples with x= 0, 0.05, 0.1, and 0.25 have been investigated by powder X-ray diffraction analyses, magnetic susceptibility (χ) measurements, and electrochemical charge and discharge test in non-aqueous lithium cell. According to the structural analyses using a Rietveld method, the occupancy of the Ni ions in the Li layer was estimated to be below 0.01 for all the samples and was eventually independent of x. The temperature (T) dependence of χ⁻¹ obtained with the magnetic field H=10 kOe indicated that all the samples are a Curie-Weiss paramagnet down to . At low T, all the samples entered into a spin-glass-like phase below T_f. The magnitude of T_f was found to decrease almost linearly with x, as in the case for the x dependences of the lattice parameters of a_h- and c_h-axes, Weiss temperature, and effective magnetic moment. It is, therefore, found that the change of the magnetic properties with x is simply explained by a dilution effect due to the increase of the quantity of Co³⁺ ions. On the other hand, the electrochemical measurements demonstrated that the irreversible capacity at the initial cycle is drastically decreased by the small amount of Co ions. Furthermore, the discharge capacity (Q_dis) for the x=0.05 and 0.1 samples are larger than that for the x=0 sample; namely, Q_dis=180 mAh g⁻¹ for x=0, Q_dis=217 mAh g⁻¹ for x=0.05, and Q_dis=206 mAh g⁻¹ for x=0.1. Comparing with the past results, the amount of Ni ions in the Li layer is found to play a significant role for determining the magnetic and electrochemical properties of LiNi_1−xCo_xO₂.     

Redistribution of cations and enhancement in magnetic properties of sol–gel synthesized Cu0.7?xCoxZn0.3Fe2O4 (0?≤?x?≤?0.5)

Cu_{0.7− x} Co _x Zn_0.3Fe₂O₄ (0 ≤ x ≤ 0.5) nanoparticles are prepared by sol–gel auto combustion method, using copper nitrate, zinc nitrate, ferric nitrate, cobalt nitrate, and citric acid as the starting materials. The process takes only a few minutes to obtain as-received Co-substituted Cu–Zn ferrite powders. X-ray diffraction (XRD), vibrational sample magnetometer and thermo gravimetric analysis are utilized in order to study the effect of variation in the Co substitution and its impact on particle size, lattice constant, density, cation distribution and magnetic properties like magnetization, coercivity, remanent magnetization, ferritization temperature and associated water content. Lattice parameter found to increase with increasing Co content, whereas X-ray density, bulk density, particle size showed decreasing trend with the Co content. Cation distribution indicates that the Co and Cu ion show preference towards octahedral [B] site, Zn occupy tetrahedral (A) site whereas Fe occupy both tetrahedral (A) and octahedral [B] site. Redistribution of cations takes place for x > 0.3. Saturation magnetization (Ms) increases from 52.99 to 79.62 emu/g (x ≤ 0.3), for x > 0.3 Ms decreases with increase in Co content x. However, coercivity, magnetocrystalline anisotropy and remanent magnetization increases with the Co²⁺ substitution.     

Doping studies of the magnetic cobaltocuprate CoSr2Y2−xCexCu2O9±δ

A structural, magnetic and electronic study of the cobaltocuprate CoSr₂Y_2−xCe_xCu₂O_9±δ (x=0.5-0.8) has been performed. All materials crystallise in the orthorhombic Cmcm symmetry space group in which chains of corner linked CoO₄ tetrahedra run parallel to the 1 1 0 direction. An antiferromagnetic transition is observed for x=0.5-0.8; T_M increases with x. A change in the dimensionality of the magnetic order occurs at x=0.8 as the interchain distance increases to a critical value. There is charge transfer between the cuprate planes and cobaltate layer as Ce doping increases, so that Co³⁺ is partially oxidised to Co⁴⁺ with a concomitant reduction in the valence of Cu. Superconductivity is not observed in any of the samples and a crossover from Mott to Efros and Shklovskii variable range hopping behaviour is evidenced as x increases from 0.5 to 0.8.     

Crystal structure, microstructure and reducibility of LaNixCo1−xO3 and LaFexCo1−xO3 Perovskites (0<x≤0.5)

Nickel and iron substituted LaCoO₃ with rhombohedrally distorted perovskite structure were obtained in the temperature range of 600-900 °C by thermal decomposition of freeze-dried citrates and by the Pechini method. The crystal structure, morphology and defective structure of LaCo_1−xNi_xO₃ and LaCo_1−xFe_xO₃ were characterized by X-ray diffraction and neutron powder diffraction, TEM and SEM analyses and electron paramagnetic resonance spectroscopy. The reducibility was tested by temperature programmed reduction with hydrogen. The products of the partial and complete reduction were determined by ex-situ XRD experiments. The replacement of Co by Ni and Fe led to lattice expansion of the perovskite structure. For perovskites annealed at 900 °C, there was a random Ni, Fe and Co distribution. The morphology of the perovskites does not depend on the Ni and Fe content, nor does it depend on the type of the precursor used. LaCo_1−xNi_xO₃ perovskites (x>0.1) annealed at 900 °C are reduced to Co/Ni transition metal and La₂O₃ via the formation of oxygen deficient Brownmillerite-type compositions. For LaCo_1−xNi_xO₃ annealed at 600 °C, Co/Ni metal, in addition to oxygen-deficient perovskites, was formed as an intermediate product at the initial stage of the reduction. The interaction of LaCo_1−xFe_xO₃ with H₂ occurs by reduction of Co³⁺ to Co²⁺ prior to the Fe³⁺ ions. The reducibility of Fe-substituted perovskites is less sensitive towards the synthesis procedure in comparison with that of Ni substituted perovskites.     

Flux growth of a new cobalt-zinc-tin ternary phase Co7+xZn3−xSn8 and its relationship to CoSn

The intermetallic compound Co_7+xZn_3−xSn₈ (−0.2<x<0.2) forms from the reaction of cobalt in zinc/tin eutectic flux. This phase has a new structure type in orthorhombic space group Cmcm, with unit cell parameters a=4.138(1) Å, b=12.593(4) Å, and c=11.639(4) Å (Z=2; R₁=0.0301). Varying the amount of cobalt in the synthesis leads to formation of a superstructure in space group Pnma, with lattice parameters a=12.5908(2) Å, b=11.6298(3) Å, and c=8.2704(2) Å (Z=4; R₁=0.0347). A Co/Zn mixed site and a partially occupied Co site in the Cmcm structure order to form the Pnma supercell. TGA/DSC studies indicate that the binary phase CoSn initially forms in the flux at 1173 K, and then reacts with the zinc in the cooling solution to form the ternary structure at 823 K. This phase exhibits Pauli paramagnetic behavior.     

Neutron diffraction study and superparamagnetic behavior of ZnFe2O4 nanoparticles obtained with different conditions

Spinel-type (S.G.= Fd3?m) ZnFe₂O₄ fine particles with sizes from 4 to 19 nm prepared by solvothermal and microwave-assisted solvothermal methods have been studied by neutron powder diffraction at room temperature. The cation distribution corresponding to mixed spinel structure (Zn²⁺_1−xFe³⁺_x)[Fe³⁺_2−xZn²⁺_x]O₄ along with the unit cell parameter has been estimated after Rietveld refinement of the obtained neutron diffraction data for all the samples. It has been found that the inversion degree parameter (x) takes values between 0.11 and 0.20 depending not only on the particle size but also on the synthesis conditions as well. All the samples behave as superparamagnetic with an effective magnetic moment per particle (μ_SP) from 7.0×10² to 7.7×10³ μ_B. The sample obtained by microwave assistance displays a different magnetic behavior as the ZFC and FC magnetic susceptibility and the magnetization versus applied field hysteresis loop measured at 5 K suggest. This is related with the dipole interactions that are a consequence of the higher inversion degree and μ_SP.     

Phase diagram, crystal chemistry and thermoelectric properties of compounds in the Ca-Co-Zn-O system

In the Ca-Co-Zn-O system, we have determined the tie-line relationships and the thermoelectric properties, solid solution limits, and structures of two low-dimensional cobaltite series, Ca₃(Co, Zn)₄O_9−z and Ca₃(Co,Zn)₂O_6−z at 885 °C in air. In Ca₃(Co,Zn)₄O_9−z, which has a misfit layered structure, Zn was found to substitute in the Co site to a limit of Ca₃(Co_3.8Zn_0.2)O_9−z. The compound Ca₃(Co,Zn)₂O_6−z (n=1 member of the homologous series, Ca_n+2(Co,Z_n)_n(Co,Zn)′O_3n+3−z) consists of one-dimensional parallel (Co,Zn)₂O₆⁶⁻ chains that are built from successive alternating face-sharing (Co,Zn)O₆ trigonal prisms and ‘n’ units of (Co,Zn)O₆ octahedra along the hexagonal c-axis. Zn substitutes in the Co site of Ca₃Co₂O₆ to a small amount of approximately Ca₃(Co_1.95Zn_0.05)O_6−z. In the ZnO-CoO_z system, Zn substitutes in the tetrahedral Co site of Co₃O₄ to the maximum amount of (Co_2.49Zn_0.51)O_4−z and Co substitutes in the Zn site of ZnO to (Zn_0.94Co_0.06)O. The crystal structures of (Co_2.7Zn_0.3)O_4−z, (Zn_0.94Co_0.06)O, and Ca₃(Co_1.95 Zn_0.05)O_6−z are described. Despite the Ca₃(Co, Zn)₂O_6−z series having reasonably high Seebeck coefficients and relatively low thermal conductivity, the electrical resistivity values of its members are too high to achieve high figure of merit, ZT.     

Nanocrystalline Ni0.6Zn0.4Fe2O4: A novel semiconducting material for ethanol detection

The structure and crystal phase of the nanocrystalline powders of Ni_1−xZn_xFe₂O₄ (0 ≤ x ≤ 0.5) mixed ferrite, synthesized by ethylene glycol mediated citrate sol-gel method, were characterized by X-ray diffraction and microstructure by transmission electron microscopy. Further studies by Fourier transform infrared spectroscopy were also conducted. Moreover, DC electrical properties of the prepared nanoparticles were studied by DC conductivity measurements. The response of prepared Ni_1−xZn_xFe₂O₄ mixed ferrites to different reducing gases (ethanol, hydrogen sulfide, ammonia, hydrogen and liquefied petroleum gas) was investigated. In particular, Ni_0.6Zn_0.4Fe₂O₄ composition exhibited high response to 100 ppm ethanol gas at 300 °C. Incorporation of palladium further improved the response, selectivity and response time of Ni_0.6Zn_0.4Fe₂O₄ to ethanol gas with the blue shift in the operating temperature by 25 °C.     

Crystal structure and electronic properties of the new compounds U3Co12−xX4 with X=Si, Ge

The new compounds U₃Co_12−xX₄ with X=Si, Ge were prepared by direct solidification of the corresponding liquid phase, followed by subsequent annealing at 1173 K. Single crystal X-ray diffraction carried out at room temperature showed that they crystallize with the hexagonal space group P6₃/mmc (no.194) and the unit-cell parameters a=8.130(5), c=8.537(5) Å and a=8.256(1), c=8.608(1) Å for the silicide and germanide, respectively. Their crystal structure derives from the EuMg_5.2 structure type, and is closely related to the Sc₃Ni₁₁Si₄ and Gd₃Ru_4−xAl_12+x types. For the present compounds, no substitution mechanisms have been observed, the partial occupancy of one Co site results from the presence of vacancies, only. The homogeneity ranges, evaluated by energy dispersive spectroscopy analysis, extend from x=0.0(2) to 0.3(2) and from x=0.0(2) to 1.0(2) for U₃Co_12−xSi₄ and U₃Co_12−xGe₄, respectively. The electronic properties of both compounds were investigated by means of DC magnetic susceptibility and DC electrical resistivity measurements. The U₃Co_12−xX₄ compounds are both Pauli paramagnets with their electrical resistivity best described as poor metallic or dirty metallic behavior.     

Synthesis of layered cathode material Li[CoxMn1−x]O2 from layered double hydroxides precursors

Cathode materials Li[Co_xMn_1−x]O₂ for lithium secondary batteries have been prepared by a new route—precursor method of layered double hydroxides (LDHs). In situ high-temperature X-ray diffraction (HT-XRD) and thermogravimetric analysis coupled with mass spectrometry (TG-MS) were used to monitor the structural transformation during the reaction of CoMn LDHs and LiOH·H₂O: firstly the layered structure of LDHs transformed to an intermediate phase with spinel structure; then the distortion of the structure occurred with the intercalation of Li⁺ into the lattice, resulting in the formation of layered Li[Co_xMn_1−x]O₂ with α-NaFeO₂ structure. Extended X-ray absorption fine structure (EXAFS) data showed that the Co-O bonding length and the coordination number of Co were close to those of Mn in Li[Co_xMn_1−x]O₂, which indicates that the local environments of the transitional metals are rather similar. X-ray photoelectron spectroscopy (XPS) was used to measure the oxidation state of Co and Mn. The influences of Co/Mn ratio on both the structure and electrochemical property of Li[Co_xMn_1−x]O₂ have been investigated by XRD and electrochemical tests. It has been found that the products synthesized by the precursor method demonstrated a rather stable cycling behavior, with a reversible capacity of 122.5 mAh g⁻¹ for the layered material Li[Co_0.80Mn_0.20]O₂.