Effect of Zn Substitution on Magnetic Properties of CuFe_2O_4： a High-Temperature Series Expansions Study

The magnetic properties of spinel ferrites Cu_（1-x）Zn_xFe_2O_4 are studied using high-temperature series expansions combined with the Padé approximates. The exchange interactions, inter and intra-sublattices J_（AA）, J_（BB） and J_（AB） are obtained using a probability distribution law. The critical exponent associated with the magnetic susceptibility is obtained.

Active plane modulation of Bi_(2)O_(3)nanosheets via Zn substitution for efficient electrocatalytic CO_(2)reduction to formic acid

Formic acid is considered one of the most economically viable products for electrocatalytic CO_(2)reduction reaction(CO_(2)RR).However,developing highly active and selective electrocatalysts for effective CO_(2)conversion remains a grand challenge.Herein,we report that structural modulation of the bismuth oxide nanosheet via Zn^(2+)cooperation has a profound positive effect on exposure of the active plane,thereby contributing to high electrocatalytic CO_(2)RR performance.The obtained Zn-Bi_(2)O_(3)catalyst demonstrates superior selectivity towards formate generation in a wide potential range;a high Faradaic efficiency of 95%and a desirable partial current density of around 20 mA·cm^(-2)are obtained at−0.9 V(vs.reversible hydrogen electrode(RHE)).As proposed by density functional theory calculations,Zn substitution is the most energetically feasible for forming and stabilizing the key OCHO*intermediate among the used metal ions.Moreover,the more negative adsorption energy of OCHO*and the relatively low energy barrier for the desorption of HCOOH*are responsible for the enhanced activity and selectivity.

Compensation of Zn substitution and secondary phase controls effective mass and weighted mobility in In and Ga co-doped ZnO material

Conductivity s and thermal conductivity k are directly related to carrier concentration while Seebeck coefficient S is inversely proportional to carrier concentration.Therefore,improving thermoelectric(TE)performance is challenging.Here,the first-time analysis of secondary phase-controlled TE performance in terms of density-of-state effective mass m*d,weighted mobility mw and quality factor B is discussed in ZnO system.The results show that the secondary spinel phase Ga2O_(3)(ZnO)9 not only impacts on k but also on s and S at high temperature,while the effect of carrier concentration seem to be dominant at low temperature.For the high-spinel-segregation sample,a compensation of dopant atoms from the spinel to substitutional sites in the ZnO matrix at high temperature leads to a low decreased rate of temperaturedependent m*d.The compensation process also induces a band sharpening,a small mw reduction,and a large B enhancement.As a result,In and Ga co-doped ZnO bulk with the highest spinel segregation achieves the greatest PF improvement by 112.8%,owing to enhanced Seebeck coefficient by 110%as compared to the good Zn-substitution sample.

Effect of Nonmagnetic Impurity Doped on the Structural and Magnetic Properties of Quasi-one-dimensional Antiferromagnet LiCuVO4

Zn2＋ ions doped quasi-one-dimensional spin-chain materials LiCul-xZnxVO4（x=0, 0.1, 0.2） were prepared by solid-state reaction and the effect of nonmagnetic Zn2＋ ions on the crystal structure, valence state and magnetic proper- ties of them were studied by X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS） and dc magnetization. The elongation of a and b axes and the shrinkage of c axis indicate a reduced effect of the Jahn-Teller distortion after Zn2＋ ions doping, while the valence state of transition metal ions in LiCu1- xZnrVO4 remains unchanged since the equi- valence doping of Zn2＋ ions on the Cu2＋ sites. The corrected Bonner-Fisher equation fitting to the susceptibility indicates that isolated dimers and spins are created along with the departure from infinite spin chains to finite ones.