Precursor synthesis and properties of iron and lithium co-doped cadmium oxide

Lithium and iron co-doped cadmium oxide Cd0.9(Li1-xFex)0.1O (x = 0.1, 0.3, 0.5, 0.7) with NaCl structure has been synthesized using formate of the composition Cd0.9(Li1-xFex)0.1(HCOO)2·2H2O as a precursor. The NMR spectroscopy results demonstrate that the structure of lithium-doped cadmium oxide appears to have impurity centers only of one type. All the synthesized samples show a metal-like conductivity as indicated by the growth of their electrical resistance with temperature increasing in the interval 78–330 K. The study of the magnetic properties of the Cd0.9(Li1-xFex)0.1O samples at 5 and 300 K revealed that they are ferromagnets, whose saturation magnetization increases with the iron concentration both at low and room temperature reaching the maximal values in the samples with a Li and Fe concentration of 3 and 7 at.%, respectively. An enhancement of the iron concentration in Cd0.9(Li1-xFex)0.1O from x = 0.5 to x = 0.7 leads to an abrupt growth of the magnetization from 0.30 to 1.94 emu/g at 5 K and from 0.16 to 1.03 emu/g at 300 K. Iron doping with a simultaneous reduction of the lithium concentration also results in an increase of the band gap. The properties of these compounds are explained on the basis of first-principles calculations of their band structure.The research was carried out within the state assignment of the Ministry of Education and Science of the Russian Federation (theme “Spin”, No. AAAA-A18-118020290104-2), supported in part by “Electrical Engineering” Shanghai class 2 Plateau Discipline, the Government of the Russian Federation (Decree No. 211, Contract No. 02.A03.21.0006), “Electrical Engineering” Shanghai class 2 Plateau Discipline and the National Natural Science Foundation of China (NSFC, Nos. 12074242, 51862032). Absorption spectra were obtained using the equipment at the Center for Joint Use "Spectroscopy and Analysis of Organic Compounds" at the Postovsky Institute of Organic Synthesis, UB RAS. The optical measurements were carried out in accordance with the scientific and research plans and state assignment of the Institute of Solid State Chemistry, UB RAS (Grant No. AAAA-A19-119031890025-9). E.V.C. acknowledges funding by Saint Petersburg State University project for scientific investigations (ID No. 73028629). TPeer reviewe

Synthesis and characterisation of new MO(OH)2 (M = Zr, Hf) oxyhydroxides and related Li2MO3 salts

Two new solid MO(OH)2 (M = Zr, Hf) oxyhydroxides have been synthesised by an ion-exchange reaction from Li2MO3 (M = Zr, Hf) precursors obtained by a citrate combustion technique. The crystal structure of the oxyhydroxides has been solved by direct methods and refined using Rietveld full profile fitting based on X-ray powder diffraction data. Both oxyhydroxides crystallize in a P21/c monoclinic unit cell and have a structure resembling that of the related salts. Detailed characterisation of the fine-structure features and chemical bonding in precursors and oxyhydroxide powders has been performed using vibrational spectroscopy, nuclear magnetic resonance spectroscopy, scanning electron microscopy, pair distribution function analysis and quantum-chemical modelling

Zinc glycolate Zn(OCH2CH2O): Synthesis and structure, spectral and optical properties, electronic structure and chemical bonding

This article presents new findings obtained from the study of formation conditions, crystal structure, thermal, spectral, optical properties and electronic band structure of zinc glycolate Zn(OCH2CH2O). This compound was synthesized by heating the solutions of zinc formate Zn(HCOO)2·2H2O in ethylene glycol (A) or in a mixture of ethylene glycol and distilled water (B). The crystal structure of Zn(OCH2CH2O) has been studied using the X-ray powder diffraction method. It is shown that the crystal structure is built via zigzag joining of [Zn4O12C8H16] tetracycles with the tetrahedrally coordinated zinc (ZnO4). Zinc atoms inside the tetracycles and the tetracycles themselves are interconnected with oxygen bridges. Complex anions OCH2CH2O2- are bonded to zinc atoms by chelation. The unit cell parameters of Zn(OCH2CH2O) are as follows: the tetragonal structure, space group I41/a (88−2), Z = 16, a = b = 11.08673(9) Å, c = 11.5902(1) Å, V = 1424.62(2) Å3. The IR and Raman spectra of Zn(OCH2CH2O) correlate fully with the results of structural analysis. Under UV excitation, the luminescence spectra of Zn(OCH2CH2O) samples synthesized following the methods (A) and (B) are characterized by emission maxima at 460 nm (blue luminescence) and 540 nm (yellow-green luminescence), respectively. Yellow-green luminescence is due to the presence of an admixture of zinc oxide nanoparticles of size 10 nm in the sample. The electron density functional method is employed to study the electronic band structure and chemical bonding in Zn(OCH2CH2O). It is shown that the 3dZn orbitals are covalently bonded to 2pO orbitals so that an octagon is formed, where the zinc atoms of four neighboring ZnO4 tetrahedrons are linked through their vertices. The feasibility of synthesizing a layered structure of Zn(OCH2CH2O) is analyzed on the basis of ab initio calculations and Voigt-Reuss-Hill theory.The X-ray study was carried out at the Multiple-Access Center for X-ray Structure Analysis at the Institute of Solid State Chemistry, UB RAS. The UV-Vis spectra were recorded using the equipment of the Multiple-Access Center for Spectroscopy and Analysis of Organic Compounds at the Postovsky Institute of Organic Synthesis, UB RAS. This work was carried out in accordance with the scientific and research plans and as defined in the state assignment for the Institute of Solid State Chemistry, UB RAS (grant No. AAAA-A19–119031890025-9). The electronic structure calculations were performed with the URAN cluster in the Institute of Mathematics and Mechanics, UB RAS. E.V.C. acknowledges support from Saint Petersburg State University (grant No. ID 90383050).Peer reviewe