Solid-solid Method Research Articles

Effects of doping by copper on electrical properties of LaCrO3 based perovskite

The use of nickel-yttria-stabilized zirconia (Ni/YSZ) as anode material for solid oxide fuel cell (SOFC) applications, presents some limitations such as poor stability in reduction/oxidation cycling, and poor sulphur tolerance which results in carbon deposition when utilizing hydrocarbon fuels. Even though lanthanum chromite (LaCrO3 noted LCO) is an excellent alternative to Ni/YSZ, it is rarely used in SOFC applications due to its poor conductivity. In order to further progress in developing LCO materials, this work was conducted to improve the conductivity of LCO by copper doping. In particular, LaCr1-xCuxO3 compounds with x = 0, 0.1, and 0.3 were synthesized via a solid-solid method. The followed preparation process allows obtaining a cubic structure with Pm-3m space group. The substitution of Cr with Cu resulted in a slight increase in lattice parameter a, but no change in structure or space group. Whereas, the band gap energy decreased from 3.68 eV for x = 0–3.06 eV for x = 0.3. The crystallite size increases with doping level. With regard to the obtained data from electrical measurements, a thermally activated and frequency depended conductivity was obtained for all samples. Furthermore, the correlated barrier hopping mechanism was proposed as a conduction mechanism, and an electrical transition from semiconductor to metallic behavior was observed. The conductivity increased also monotonously with Cu content and shows a maximum value of 4.5 S/m for x = 0.3. Besides, the tangent loss shows a maximum value of around 104 for x = 0.1. The LaCr0.7Cu0.3O3 compound could be a good candidate for SOFC applications, while LaCr0.9 Cu0.1O3 can be used as a heating element.

Study of the doping of Sr by Ag in manganites La0.57Nd0.1Sr0.33-xAgxMnO3 (0.00–0.15) on assessment structural, magneticand Magnetocaloric at room temperature

We describe in this manuscript the effect of the substitution of a divalent element such as strontium Sr2+ by a monovalent element such as silver Ag+ on the variation of the Mn-Mn distance between two adjacent MnO6 octahedra and also on the evolution of Mn -O -Mn and also on the overlap of manganese d orbitals and oxygen 2p orbitals. then in this study, we synthesized by the solid-solid method the polycrystalline oxides La0.57Nd0.1Sr0.33-xAgxMnO3 (x = 0 and 0.15) LNSAMO.X-ray diffraction study shows that these compounds crystallize in the rhombohedral structure of space group R-3C and exhibit a second Mn3O4 phase of space group I 41 / amd. All the magnetization curves show a high temperature transition from a ferromagnetic state to a paramagnetic state near the Curie temperature (TC) and a second transition associated with the secondary phase Mn3O4. The Curie temperature decreases from 321 K to 307 K as the disorder increases. However, we have noticed that the substitution of strontium which is a magnetic element by non-magnetic silver causes the increase of the magnetization as well as the decrease of the temperature of Curie TC. When an external magnetic field μ0H = 5 T, we find that the values ofmagnetic entropy (ΔSMmax) are equal to 2.68, 4.55 and 5.08 J Kg 1 K 1, respectively, for x = 0.0, 0.1 and 0.15 samples. The relative cooling power (RCP) is around 80.10 J/kg, 137 J/kg,146.74 J/kg of X = 0, X = 0.1 f, X = 0.15 compounds for the 5T magnetic field. By basing the results of this work, we achieve that the controlled Ag doping adapts perfectly to the magnetic and Magnetocaloric characteristic of LNSMO Which perform a significant function in the realization of much potential applying of the compound in the field of approximately-room temperature magnetic refrigeration technology.

Comparison study on regeneration of spent ternary materials by molten salt solid-liquid method and traditional solid-solid method

Lithium-ion batteries (LIBs) contain a variety of toxic inorganic and organic compounds, and the spent cathode materials are high quality resources of Ni, Co, Mn, and Li elements. In this case, how to efficiently deal with spent materials has become an urgent problem. In this work, the regeneration of spent ternary materials via molten salt solid-liquid method and traditional solid-solid method are studied comparatively. Ordered and uniform crystals in MS-NCM are successfully grown in liquid medium of molten salts. The regenerated TS-NCM by traditional sintering method still presents inhomogeneous larger and smaller crystals. Moreover, only regeneration by molten salt method effectively removes F-contained impurity on the surface of spent materials, and the Ni3+ and Mn3+ on the crystal surface of MS-NCM are close to the values in commercial sample (Com-NCM). After 100 cycles at 0.2 C rate, MS-NCM and TS-NCM respectively deliver 149.1 mA h g−1 and 123.2 mA h g−1, maintaining 98.1% and 84.4% of their initial capacity. MS-NCM presenting better electrochemical performance than TS-NCM is attributed to the efficient regeneration of the spent cathode material in liquid medium of molten salts.

Thermally stable black metal oxide-based modified pigment mix for solar selective absorbers

PurposeA mixed metal oxide-based spinel ceramic pigment has been successfully synthesized incorporating inorganic, high-temperature stable furnace cement as an inbuilt binder. Step by step synthesis was done for the spinel and cement mix formulations.Design/methodology/approachThe pigment mix was synthesized by a solid-solid method where the inorganic binder was incorporated in the mix. The results suggested that CoCuMn-based spinel ceramic pigment with cement mix could be obtained at an annealing temperature of 1,100ºC for 1 h and the size, morphology and crystallinity of spinel mix were greatly influenced by the calcination temperature.FindingsThe pigment mix synthesized was applied as a coating to different substrates such as aluminum, glass and Mild steel. The results revealed that spectral selectivity of TSSS paint coatings based on the CoMnCu spinel ceramic mix was much better than that of solvent-based coatings for high-temperature applications. The presence of cement as an inorganic binder makes the functioning and application of paint easy as it becomes that of a waterborne type.Originality/valueEase of application, stability at high temperatures, best absorptivity at the solar selective spectrum and excellent adhesion properties for the selected surface are the key features of the designed pigment system. The applied pigment mix was studied as a coating to get the results for solar selective system.

PEMBUATAN DAN KARAKTERISASI KOMPOSIT LiBOB/MgCl2 DENGAN METODE SOLID STATE REACTION

The manufacture and characterization of the lithium bus Composite (oxalate) borate with the addition of magnesium chloride (LiBOB/MgCl2). Electrolytes as a media transfer ion battery, plays an important role in the charge-discharge process of lithium ion batteries. The basic ingredients used in the study are lithium hydroxide (LIOH), Borid acid (H3BO3), Our acid dehydrate (H2C2O4 • 2H2O) and magnesium chloride hexahydrate (MgCl2 • 6H2O). The method used in this research is solid state reaction or known as solid-solid method. Based on the results of the XRD characterization, shows the peaks of LiBOB experiencing a shift after being added with 2.5%; 5% and 7.5% MgCl2 • 6H2O, in addition it also raises new peaks of magnesium. While the spread of the material is blown the sample appears evenly with the SEM-EDX test, however there are some elements that are experiencing clotting. And the FTIR test showed a change in the frequency of each mass increase of MgCl2 • 6H2O, but did not cause peak changes in each sample. In the EIS test results, obtaining a low electrical conductivity value, due to agglomeration of the material after the addition of elemental magnesium that is ionic. Thus also causes the diffusion of ions to lower.

Structural, dielectric, ferroelectric, and electrocaloric properties of 2% Gd2O3 doping (Na0.5Bi0.5)0.94Ba0.06TiO3 ceramics

Structural, dielectric, and ferroelectric properties, and electrocaloric effects of pure and Gd doped (Na0.5Bi0.5)0.94Ba0.06TiO3 ceramics prepared by the conventional solid-solid method have been carried out. The X-ray diffraction analysis confirms a pure perovskite structure with the coexistence of tetragonal and rhombohedra structures in both powders. The thermal and frequency dependences of the dielectric constants of both ceramics revealed relaxor behavior. The two compounds exhibited two phase transitions: ferroelectric/antiferroelectric (FE/AFE) transition followed by an antiferroelectric/paraelectric (AFE/PE) transition at higher temperatures. Remarkably, we noticed that the small amount of Gd doping (2%) highly enhanced the dielectric properties of the parent compound by about 71%. The phase diagram was as well influenced by the Gd doping, where the FE/AFE transition temperature rose from 90 in the parent compound to 115 °C in the doped one whereas the AFE/PE transition temperature was decreased from 320 to 270 °C, respectively. The direct electrocaloric measurements performed on both compounds showed that the ferroelectric/antiferroelectric phase transition was accompanied by a significant electrocaloric effect. The Gd3+ doping improved the electrocaloric properties of the parent compound, where a remarkable temperature variation of 1.4 K was obtained in the doped ceramic. The results of the direct electrocaloric measurements will be compared and discussed with those derived from the indirect method.

Effect of Elaborating Method on Magnetic and Magnetocaloric Properties of La0.65Ca0.35−xKxMn03(0 ≤ x ≤ 0.2) Manganites

A comparative study of the structural, magnetic, and magnetocaloric properties of La0.65Ca0.35−xKxMn03 powder samples elaborated by solid-solid and sol-gel methods is given. The X-ray diffraction patterns at room temperature show that all our synthesized samples elaborated by both methods are single phase. Samples elaborated by solid-solid method crystallize in the orthorhombic structure (Pbnm space group) for x ≤ 0.1 and in the rhombohedral one (R-3C space group) for x= 0.2, while for x = 0.15, the system begins to exhibit both phases with different proportions. The structural transition from Pbnm space group to R-3C one occurs for x > 0.15 for samples elaborated by sol-gel method. Magnetization measurements versus temperature in a magnetic applied field of 50 mT indicate that all our studied samples display a paramagnetic ferromagnetic transition with decreasing temperature. Curie temperature TC increases with increasing K content. It increases from 248 K for x = 0 to 310 K for x = 0.2 for samples elaborated by solid-solid method and from 275 K for x = 0 to 320 K for x = 0.2 for samples elaborated by sol-gel route. The maximum of the magnetic entropy change ${\mathrm {\Delta } S}_{M}^{\text {Max}}$ under Δμ0H= 5 T is obtained for x = 0.2 sample elaborated by both methods. ${\mathrm {\Delta } \mathrm {S}}_{\mathrm {M}}^{\text {Max}}$ is found to be 5.78 J/kg/K at 305 K and 7.5 J/kg/K at 325 K for sample elaborated by solid-solid and sol gel, respectively. The relative cooling power RCP exhibits a maximum value of 313 J/kg at Δμ0H= 5 T for x = 0.05 elaborated by solid-solid method and 300 J/kg at Δμ0H= 5 T for x = 0.2 elaborated by sol-gel method.

Study of the physical properties of La2 − xErxTi2O7(0 ≤ x ≤ 0.075) compounds

New complex magnetic frustrated materials La 2 − x Er x Ti 2 O 7 (0 ≤ x ≤ 0.075) have been synthesized by solid-solid method. The crystallographic and magnetic properties were studied as a function of substitution of the La 3+ ion by the Er 3+ one. All samples are found to be single phase and crystallize in the monoclinic structure with P 21 space group. Magnetic measurements have revealed the presence of dominant antiferromagnetic interactions and the absence of magnetic ordering until a temperature of 2 K. The magnetic study suggests that the Curie-Weiss temperature ( θ CW ) is negative, as expected in the frustrated lanthanide sublattice in the Ln 2 – x Ln’ x M 2 O 7 structure. From the frustration index f = - θ CW / T N , we have deduced the presence of a strong frustration phenomenon. The critical properties of the antiferromagnetic behavior, for x = 0.025, 0.05 and 0.075 samples, have been investigated. It was found that the 2D-self-avoiding walk (SAW) model is the best one to describe the critical phenomena.