An enhanced sol-gel combustion method was used to synthesize different porous Sc 3+ -doped Li 3 V 2-x Sc x (PO 4 ) 3 /C (x = 0.00, 0.05, 0.10 and 0.15) compounds. The substitution of Sc 3+ into the V 3+ sites of Li 3 V 2-x Sc x (PO 4 ) 3 /C expands the lattice volume along with the enlargement of Li + diffusion channel, which is beneficial for Li + transportation and ionic conductivity improvement. Besides, the Sc 3+ doping content exhibits a great impact on the morphology of Li 3 V 2-x Sc x (PO 4 ) 3 /C composite. The pristine Li 3 V 2 (PO 4 ) 3 /C are constituted of porous particles and nanorods , and the ratio of nanorods to particles can be controlled by adjusting the amount of Sc 3+ doping since the ratio of nanorods to particles decreases with increasing Sc 3+ doping content. When Sc 3+ doping content increases to a certain level (x = 0.15, Li 3 V 1.85 Sc 0.15 (PO 4 ) 3 /C), the nanorods are hardly seen. Li 3 V 1.90 Sc 0.10 (PO 4 ) 3 /C with higher tapped density, better reversibility, smaller resistance and larger Li + diffusion coefficient demonstrates outstanding rate performance and cyclic stability, together with high specific discharge capacities of 130.2 and 92.9 mAh g −1 at 0.5 and 20 C, respectively. Furthermore, a superior specific discharge capacity of 85.8 mAh g −1 was retained at 20 C following 1000 cycles. Overall, a novel approach for the preparation of high-performance Li 3 V 2-x Sc x (PO 4 ) 3 /C cathodes with different morphologies for lithium-ion batteries is provided.
Jiadong Hou,Yufeng Liu,Chufei Cheng,Fuhao Cheng,Teng Su,Chao Ma,Yang Miao,Xiaomin Wang
High entropy materials offer optimal conditions for regulating and modifying new material properties due to their vast composition space. Through traditional solid phase sintering , this article successfully synthesized a series of Sr(Ti 0.2 Zr 0.2 Y 0.2 Sn 0.2 Hf 0.2 Sc 0.2x )O 3-σ high entropy perovskite oxides with varying Sc 3+ doping concentrations and comprehensively investigated the microstructure morphology, crystal structure, and electrical conductivity of Sc-doped HEPs as well as their influence on oxygen transfer rate. The results demonstrate the successful incorporation of Sc 3+ into the high entropy lattice, resulting in a transformation of the crystal to a positively cubic structure with enhanced reciprocity. While the lattice vibration of BO 6 octahedron is weakened by the introduction of Sc 3+ , it has no impact on the phase stability of the crystal structure. Moreover, The results of the electrochemical impedance spectroscopy test demonstrate that at a temperature of 750 °C, with a doping amount of Sc 3+ at 0.14, the conductivity (σ) of Sc 3+ is measured to be 5.74 × 10 −3 S/cm, exhibiting an increase of 61.7% compared to non-doped samples. Correspondingly, the activation energy (Ea) is reduced from 0.51 eV to 0.39 eV as well. This doping strategy effectively expands the potential applications of high entropy perovskite oxides in solid oxide fuel cells (SOFCs). These findings serve as a driving force for further investigation into high entropy ceramics of the strontium series that exhibit optimal properties.
Jie Yang,Jiujun Zhu,Laihui Luo,Wei Xie,Weiping Li,Peng Du
To settle the thermal quenching and dissatisfied sensitivity of luminescent materials, a series of Tm 3+ /Yb 3+ /Sc 3+ -tridoped Lu 2 W 3 O 12 upconverting microparticles was synthesized through sol-gel method. In-situ X-ray diffraction results reveal that the resultant samples have good negative thermal expansion (NTE) properties, which can be improved by Sc 3+ doping. Upon 980 nm excitation, the final products can emit brightness upconverison (UC) emissions and their intensities can be enhanced by Yb 3+ and Sc 3+ doping. Moreover, the temperature-dependent UC emission spectra suggest that the designed compounds possess anti-thermal quenching luminescence. Specially, these UC emissions from 1 G 4 , 3 F 2,3 and 3 H 4 levels show different responses to temperature, allowing their feasibilities in optical thermometry. Via utilizing the fluorescence intensity ratio technique to analyze the temperature-associated UC emissions from non-thermally coupled levels (non-TCLs), one knows that maximum absolute and relative sensitivities of developed upconverting microparticles are 0.124 K –1 and 3.105%/K, respectively, while those of the resultant upconverting microparticles are 4.895×10 –5 K –1 and 1.774%/K, respectively, when the TCLs are used. Our findings verify that the utilization of NTE effect is an efficient route to induce the anti-thermal quenching UC luminescence, and the thermometric properties of luminescent materials can also be regulated by selecting proper sensing strategy, spatial mode and doping content.
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