Nanostructured HoFeO_(3)powders were obtained by solution combustion method at various glycinenitrate ratios(G/N=0.2,0.4,...,1.4).According to X-ray powder diffractometry data,the presence of two modifications of HoFe...Nanostructured HoFeO_(3)powders were obtained by solution combustion method at various glycinenitrate ratios(G/N=0.2,0.4,...,1.4).According to X-ray powder diffractometry data,the presence of two modifications of HoFeO_(3)in the synthesized samples was established:orthorhombic(Pbnm)and hexagonal(P63/mmc).The crystallite size of the obtained compositions varies from 62±6 to 29±3 nm,depending on the G/N ratio.From magnetic structure studies,it is found that HoFeO_(3)obtained with a stoichiometric amount of glycine in the reaction solution is in the magnetically ordered state and is represented by a sextet with quadrupole splitting(QS)=0 mm/s,isomeric shift(IS)=0.36 mm/s and effective field strength(Heff)=497 kOe.According to the results of vibrational magnetometry,it is found that the orthoferrites obtained have a ferromagnetic structure,the main parameters of which(Ms,Mr and Hc)systematically change with a change in the redox ratio of the reaction mixture and,as a consequence,their phase composition,and reach maximum values at a G/N ratio=0.6.In the samples obtained with a significant excess and lack of glycine(G/N=0.2 and 1.4),despite their amorphous nature,hysteresis loops characteristic of the ferromagnetic state of the substance is observed.It is hopeful to obtain a pure hexagonal modification of HoFeO_(3)via heat treatment on amorphous products of glycine-nitrate combustion.展开更多
文摘Nanostructured HoFeO_(3)powders were obtained by solution combustion method at various glycinenitrate ratios(G/N=0.2,0.4,...,1.4).According to X-ray powder diffractometry data,the presence of two modifications of HoFeO_(3)in the synthesized samples was established:orthorhombic(Pbnm)and hexagonal(P63/mmc).The crystallite size of the obtained compositions varies from 62±6 to 29±3 nm,depending on the G/N ratio.From magnetic structure studies,it is found that HoFeO_(3)obtained with a stoichiometric amount of glycine in the reaction solution is in the magnetically ordered state and is represented by a sextet with quadrupole splitting(QS)=0 mm/s,isomeric shift(IS)=0.36 mm/s and effective field strength(Heff)=497 kOe.According to the results of vibrational magnetometry,it is found that the orthoferrites obtained have a ferromagnetic structure,the main parameters of which(Ms,Mr and Hc)systematically change with a change in the redox ratio of the reaction mixture and,as a consequence,their phase composition,and reach maximum values at a G/N ratio=0.6.In the samples obtained with a significant excess and lack of glycine(G/N=0.2 and 1.4),despite their amorphous nature,hysteresis loops characteristic of the ferromagnetic state of the substance is observed.It is hopeful to obtain a pure hexagonal modification of HoFeO_(3)via heat treatment on amorphous products of glycine-nitrate combustion.
