Pure YMnO3 Research Articles

Investigations on structural and electrical properties of YMnO3 based mixed valent manganites

In this communication, the effect of doping of divalent cations (Sr, Ca) at Y–site in pure YMnO3 on their structural and electrical properties has been investigated. X–ray diffraction reveals dual phase nature of Ca–doped sample. The dielectric behaviours have been fitted using cole–cole relaxation. Role of secondary phase of 41% hexagonal YMnO3 coexists with 59% orthorhombic Y0.9Ca0.1MnO3 for Ca–doped YMnO3 compound has been discussed where orthorhombic phase provides major contribution for large dielectric constant. The ac conductivity has been explained by correlated barrier hopping mechanism. The current–voltage characteristics have been understood using Simmon’s model.

Skillfully grafted C O functional group to enhance the adsorption/photocatalytic mechanism of YMnO3/MgAl2O4 heterojunction photocatalysts

The YMnO3 with different manganese salts includes MnSO4·H2O, MnCO3 and C4H6MnO4·4H2O and YMnO3/MgAl2O4 heterojunction photocatalysts (YMO/MAO) with different mass percentage of MgAl2O4 were synthesized by a simple wet chemistry method combined with low temperature sintering technology. The effects of manganese salts on the structure, functional groups, morphology, charge states and optical properties of YMnO3 phase were studied in detail. The pure YMnO3 with the uniformity of particles can be obtained when only C4H6MnO4·4H2O is used as manganese source. The results confirmed that the YMO/MAO heterojunction was constructed by one step low-temperature sintering technique. The YMnO3/wt 10 % MgAl2O4 photocatalyst exhibits high optical absorption coefficient and highest adsorption capacity of 122.86 mg/g and degradation percentage of 98.98 % for the degradation of Congo red (CR), 86.16 % for the degradation of tetracycline hydrochloride (TC) and 72.51 % for the degradation of tetrabromo bisphenol A (TBBPA). The hydroxyl and superoxide radicals dominated the photocatalytic reaction process of YMO/MAO for the degradation of CR, TC and TBBPA. The present work pioneers the potential application of YMO/MAO grafted by CO functional group as dyes, antibiotics and persistent organic pollutants (POPS) adsorption / degradation catalyst and further provides technical reference for the synthesis of others heterojunction photocatalysts.

Investigations of structural and transport properties of Ca doped yttrium manganites

ABSTRACTPresently, the effect of divalent Ca ions on the structural and transport properties of YMnO3 is studied. A series of (Y1-xCaxMnO3 x = 0.00, 0.03, 0.05, 0.1, 0.25) samples were synthesized by solid state reaction method. X-ray diffraction shows that pure YMnO3 have hexagonal while Ca doped compounds possess mixed (hexagonal and orthorhombic) phase for all concentrations of Ca. Ferroelectric behavior of all samples was also investigated by PE loop. Furthermore, dielectric constant is found to improve after Ca doping which is understood in terms of electronic phase separation that generally occurs in charge ordered manganites.

Effects of Doping on the Magnetic Properties and Frustration of Hexagonal YMn0.9A0.1O3 (A=Al, Fe, and Cu)

The doping effects on the frustration and the magnetic properties in hexagonal compounds of YMn0.9A0.1O3 (A=Al, Fe and Cu) are investigated. Experimental results indicate that both the non-magnetic and magnetic ion dopants lead to the increase of magnetic moments and the decrease of the absolute value of Curie—Weiss temperature (|θcw|). Compared with pure YMnO3, the geometrical frustration of YMn0.9A0.1O3 is greatly suppressed and the magnetic coupling in that exhibits dopant-dependent. In addition, for the doped YMn0.9A0.1O3, the antiferromagnetic transition temperature (TN) is also suppressed slightly, which shows an abnormal dilution effect and it may be ascribed to the reduction of frustration due to the chemical substitution.

Disorder-driven spin-reorientation in multiferroic h-YMn1−xFexO3

Magnetic structure evolution of multiferroic hexagonal YMn1−xFexO3 (x = 0, 0.05, and 0.1) has been studied by carrying out detailed temperature-dependent neutron diffraction at zero and 5 T fields. Thermodynamic data confirm antiferromagnetic ordering at TN in all the compositions. Our sub-TN neutron diffraction results assign the magnetic structure of pure YMnO3 to Γ1 irreducible representation. Over the perturbative-doping range, magnetic structure changes via Γ1 + Γ2 for YMn0.95Fe0.05O3 on to Γ2 for YMn0.9Fe0.1O3, as the maiden compositional analogue of spin-reorientation; its occurrence in temperature-domain already reported for several manganites. Moreover, while the large thermal isostructural changes observed above TN are subdued in the ordered state, small alterations by the applied 5 T-field are relatively uniform across, confirming strong magneto-elastic nature of the system. Decrease of the ordered magnetic moment (μord) and planar magnetic frustration noted with Fe-doping is enhanced by the applied field, apparently through canting.

Local structural studies of hole doped hexagonal multiferroic Y(Mn,Zn)O3

We examined the local structure of hole-doped hexagonal multiferroic YMn0.9Zn0.1O3 using x-ray absorption fine structure analysis. It was shown that Zn atoms substitute Mn atoms while keeping the bipyramidal oxygen coordination unchanged. Comparative study with pure YMnO3 further showed that the Mn-O bond length splitting is diminished by approximately 0.05 Å, suggesting an enhanced orbital hybridization in the planar Mn-O bonds due to additional Mn3+ → O2− electron transfer near the Zn2+ ions. It is a conclusive experimental evidence that Zn doping indeed introduces hole doping on to the two dimensional Mn sublattice of the hexagonal multiferroic YMnO3.

Deposition of Silver Nanoparticles on Yttrium Manganese Oxide Powders.

ABSTRACTFollowing a novel silver nanoparticles synthesis pathway, pre-synthesized silver nanoparticles (4.4 nm of average diameter) were deposited on a substrate of yttrium manganese oxide. The method takes advantage of the spontaneous reduction of silver 2-ethylhexanoate in dimethyl sulfoxide (DMSO) at 50° C. Sodium citrate was used as capping agent. Silver nanoparticles dispersions mixed with yttrium manganite were kept for several days, at room temperature, in an Erlenmeyer flask wrapped in aluminum foil. Pure yttrium manganese oxide was prepared by solid state reaction of stoichiometric mixtures. The characterization of the samples mainly involved X-ray powder diffractometry and electron microscopy. Magnetic susceptibility was measured using a Quantum Design MPMS-5S SQUID magnetometer. Two samples were prepared: (I) YMnO3/Ag (1×10-3 M) and (II) YMnO3/Ag (5×10-2 M). The Ag nanoparticles deposition of (I) was confirmed by an increase in the surface area and a qualitative elemental analysis for silver. In (II) <10 nm silver nanoparticles were clearly appreciated by XRD and images of High Resolution Transmission Electron Microscopy. The measured value of magnetic susceptibility of (II) is slightly larger than pure YMnO3.