Effect Of Ho Doping Research Articles

Investigation on doping behavior of Ho ions in Lu2SiO5 lattice by XRD Rietveld refinement and first-principles calculations

The effect of Ho doping on Lu2SiO5 lattice parameters and its occupation preference were investigated by experimentally and theoretically. A series of (Lu1-xHox)2SiO5 precursors were synthesized by a Sol-gel processing, the phase evolution behaviors were explored by XRD characterization after being calcined under temperatures ranging from 975 °C to 1300 °C. It was discovered that the crystallization temperature of synthetic precursors from amorphous to X1-(Lu1-xHox)2SiO5 phase was about 975 °C, and the temperatures of phase transformation from X1-(Lu1-xHox)2SiO5 to X2-(Lu1-xHox)2SiO5 varied from 1100–1300 °C. The defect formation energies of Ho substituted in X2- Lu2SiO5 were obtained by first-principles calculations, which indicated that the Ho3+ was prone to occupy the coordination polyhedral of [LuO7]. Furthermore, it was found that the introduction of Ho into X2- Lu2SiO5 caused the increasing of lattice parameters and the distortion of [LuO7] coordination polyhedron, which contributed to regulate and control the physical and chemical properties.

The effect of Ho-doping on the synthesis, structure and magnetic characteristics of ZnFe2O4-based nanopowders

The successful production of nanopowders consisting of Ho-doped zinc ferrite (ZnFe2-xHoxO4, with x values ranging from 0 to 0.08) has been accomplished using the glycine-nitrate combustion (GNC) method, followed by calcination in air. Various analytical techniques, such as EDXS, DTA-TG, SEM, PXRD, Raman spectroscopy, and vibrating sample magnetometry (VSM), were employed to examine the resulting samples. The outcomes of our investigation indicated that an excess of fuel during the GNC process yields X-ray amorphous foamy products, which subsequently crystallize after being held at a temperature of 550 °C for a duration of 4 h. PXRD data analysis showed that the obtained samples consist of single-phase Ho-doped zinc ferrite with a spinel structure. The incorporation of holmium into the ferrite spinel structure was established to occur when the calcination temperature is elevated to 700 °C. Rietveld refinement revealed that the degree of inversion varies from 0.078 to 0.309 as the level of Ho-doping increases from x = 0 to x = 0.08. Furthermore, the incorporation of Ho leads to a more than twofold reduction in the crystallite size of ZnFe2-xHoxO4, decreasing from 61.7 to 27.3 nm. The magnetic properties of the nanopowders are shown to be systematically altered by changes in the degree of inversion and the crystallite size of zinc ferrite, which are interrelated with the holmium content. For instance, the saturation magnetization (Ms) increases by 20% and attains a value of 54.9 kOe at x = 0.08. This finding suggests that the magnetic behavior of ZnFe2–xHoxO4 nanoparticles can be deliberately adjusted, making them a promising candidate for functional materials in the field of magnetic hyperthermia. In summary, this research provides valuable insights into the synthesis, structure, and magnetic properties of Ho-doped zinc ferrite nanopowders, underscoring their potential applications in the realm of magnetic hyperthermia.

The Effect of Ho-Doping on the Synthesis, Structure and Magnetic Characteristics of Znfe2o4-Based Nanopowders

The Effect of Ho-Doping on the Synthesis, Structure and Magnetic Characteristics of Znfe2o4-Based Nanopowders

Effect of Ho doping on the crystal structure, surface morphology and magnetic property of BiFeO3 thin films prepared via the sol-gel technology

Multiferroic material bismuth ferrite (BiFeO3 = BFO) and Ho-substitution (Bi1-xHoxFeO3, x = 0.05, 0.10, 0.15, 0.20) thin films were successfully fabricated on silicon (110) substrates by the sol-gel approach. The doping-Ho effects on crystal structure, surface morphology and magnetic property were investigated. The X-ray diffraction (XRD) revealed that the Ho-substitution thin films underwent a phase transition from the rhombohedral to the orthorhombic structure. The changes in Ho-substitution and pure BFO surface appearance were analyzed using the Field Emission Scanning Electron Microscopy (SEM). Meanwhile, the saturation magnetization (Ms) of Ho-substitution samples obtained remarkable augment with the increase in Ho-doping due to the enhancement of superexchange interactions between Fe-O-Fe and spatial modulation for helical structure destruction. The heightening of superexchange interactions is attributed to the reduction of oxygen vacancies because of Ho3+ ions in a stable status.

Structural, surface morphology, dielectric and magnetic properties of holmium doped BiFeO3 thin films prepared by pulsed laser deposition

In this work, Bi1-xHoxFeO3 (with x = 0, 0.05, 0.10, 0.15 and 0.20) thin films were successfully grown on Si (100) substrates using pulsed laser deposition and the effect of Ho doping on the crystal structure, dielectric and magnetic properties were studied. X-ray diffraction studies on undoped BiFeO3 confirmed the presence of a rhombohedral phase with crystallite sizes in the 14–24 nm range. The surface morphology and microstructure of the thin films were analysed by field emission scanning electron microscopy and atomic force microscopy. The results reveal that the grain size decreases as the Ho doping concentration increases. X-ray photoemission spectroscopy was used to identify the chemical bonding, valance band and core levels of Ho doped BiFeO3 thin films. Dielectric constant and loss in Ho doped samples has been measured using a vector network analyzer and shows good dielectric behaviour compared to undoped BiFeO3. A vibrating sample magnetometer was used to investigate the magnetic properties for Ho doping with concentrations of x ≥ 0.15. In comparison to undoped BiFeO3, the doped films exhibited larger remanence and saturation magnetization. The enhancement of these properties due to Ho doping is discussed along with their relevance in designing multiferroic materials based on Bi1-xHoxFeO3 films for magnetic field sensors, multiple-state memories and spintronic elements.

Effect of Ho-doping on structural, electrical and magnetic properties of La0.7Sr0.3MnO3 ceramics prepared by Plasma-Activated Sintering

Different components of La0.7−x Ho x Sr0.3MnO3 (LHSMO, x = 0, 0.1, 0.2, 0.3) ceramics were fabricated by Plasma-Activated Sintering (PAS), so as to study the correlation between the contents of Ho3+ and the structural, electrical, magnetic properties. XRD and SEM confirmed that LHSMO ceramics prepared by PAS exhibited high-purity phase and dense microstructure. The measurement of electrical resistivity showed that the resistivity of LHSMO ceramics increased, and the metal–insulator transition temperature decreased with the increasing Ho-doping content. The resistivity data were then fitted using various empirical equations, and the conduction mechanism of LHSMO ceramics was found to be in accord with the electron–magnon scattering process in the low-temperature region and the small polaron hopping model in the high-temperature region. Lastly, we calculated the values of magnetoresistance of the LHSMO ceramics, which increased with increasing Ho-doping content, from 3.5% for x = 0 to 14.6% for x = 0.3. Therefore, the doping of Ho3+ into La0.7Sr0.3MnO3 can effectively enhance the low-field magnetoresistance effect.

Effect of Ho3+doping on the electric, dielectric, ferromagnetic properties and TC of BiFeO3 ceramics

Multiferroic Bi1−xHoxFeO3 (x=0, 0.05, 0.1, 0.15, 0.2) ceramics have been prepared by rapid liquid phase sintering method. The effect of Ho doping on the structure, electrical, dielectric, ferromagnetism properties and TC of BiFeO3 ceramics is studied. The result shows that all the peaks for Bi1−xHoxFeO3 samples can be indexed according to the crystal structure of pure BiFeO3 by XRD. When x=0.15 and 0.2, the samples consist of two phases including rhombohedral and orthorhombic. Ho doping BiFeO3 enhanced the electrical properties with lower leakage current density. This dielectric behavior of Bi1−xHoxFeO3 ceramics varies with content x and frequency, which might be understood in terms of oxygen vacancy, the displacement of Fe3+ ions and lattice phase transition. The magnetic moment of Bi1−xHoxFeO3 ceramics varies with temperature from 300 to 1000K at 5kOe. It shows that the TN of BiFeO3 changes slightly from 638K to 632K with Ho3+ doping. The magnetic Curie temperature of Bi1−xHoxFeO3 will reduce from 970K to 890K with increasing Ho3+ content, depending mainly on the Fe–O–Fe super-exchange and magnetic structure of relative stability. By measuring the magnetic hysteresis loops, all the samples exhibit weak ferromagnetic behavior under 890K and paramagnetism above 890K. It evidences that the ferromagnetic phase transition of Bi1−xHoxFeO3 samples occurs at 890K.

Effect of Ho Doping on Structure and Ferroelectric Property of Bi<SUB>4-x</SUB>Ho<SUB>x</SUB>Ti<SUB>3</SUB>O<SUB>12</SUB> Ceramics

以Ho为掺杂元素, 采用热压烧结方法制备Bi 4- x Ho x Ti 3 O 12 陶瓷, 重点研究了Ho掺杂量对其物相组成、致密度、微观结构和铁电性能的影响. 首先以Bi 2 O 3 、TiO 2 和Ho 2 O 3 微粉为原料, 利用固相反应在900℃合成出主晶相为Bi 4 Ti 3 O 12 的Bi 4- x Ho x Ti 3 O 12 ( x =0~0.8)粉体; 然后, 将合成粉体在850℃、30 MPa条件下热压烧结, 当Ho掺杂量 x =0~0.4得到了物相单一、整体致密(>99%)的Bi 4- x Ho x Ti 3 O 12 陶瓷. 随Ho掺杂量的增加, Bi 4- x Ho x Ti 3 O 12 陶瓷的剩余极化强度呈现先增大后减小的趋势, 主要与氧空位浓度和不同掺杂浓度引起的掺杂位置的不同有关. 在Ho掺杂量 x =0.4时, 其剩余极化强度最大(2 P r =13.92 μC/cm 2 ), 远大于未掺杂的Bi 4 Ti 3 O 12 陶瓷, 说明适量Ho掺杂能有效改善其铁电性能.

Effect of Ho doping on piezoelectric properties of BCZT ceramics

Lead-free (Ba0.99Ca0.01)(Ti0.98Zr0.02)O3 (BCZT)+xmol% Ho (x=0–0.6) ceramics were prepared using solid-state reaction technique. High piezoelectric coefficient of d33=330 pC/N and planar electromechanical coupling factor of kp=40% were obtained at x=0.2%. Furthermore, greatly enhanced temperature stability of the piezoelectric properties was obtained in the temperature range from 20 to 100°C, in which the Ho doped BCZT ceramics exhibited pure tetragonal phase. With the increase of Ho content, the orthorhombic–tetragonal phase transition shifted towards low temperature, while Curie temperature (Tc) remained at about 120°C. The results indicate that Ho doped BCZT ceramics could be promising candidate as lead-free piezoelectric materials.

Effect of Ho Doping on the High-Temperature Thermoelectric Properties of Ca<sub>3</sub>Co<sub>4</sub>O<sub>9</sub>-Based Oxides

Ca3-xHoxCo4O9 (x=0.0, 0.15, 0.3, 0.45) samples were prepared using solid reaction and the effect of Ho doping on their high thermoelectric properties were investigated. The substitution of Ho for Ca resulted in an increase of both thermopower and electrical resistivity which could be attributed to the decrease of hole concentrations. The Ho-doped samples had lower thermal conductivity than Ca3Co4O9 due to their lower electronic and lattice thermal conductivity. The largest ZT values were attained in Ca2.7Ho0.3Co4O9 sample.

Effect of Ho-doping on microstructure and magnetostriction of TbDyFe alloys

Tb 0.3Dy 0.7Ho x Fe1.95 ( x=0.00, 0.05, 0.10, 0.15, 0.20, 0.35, 0.50, 0.65) quaternary alloys were prepared by arc-melting and followed by annealing. The phases present and structure of the alloys were determined using a D8-Advance X-ray diffractometer. The magnetostriction of the alloys was studied by standard strain gauge technique. The dependence of Ho content on the structure, magnetostriction and density of the alloys was investigated in detail. The research results showed that Ho-doping did not change MgCu 2-type cubic Laves structure in Tb 0.3Dy 0.7Fe 1.95. When Ho content x≤0.2, rich rare earth phase presented in the alloys increased and magnetostriction of the alloys reduced evidently with increasing x, but for alloys with x>0.2, the content of rich rare earth phase started to reduce and the magnetostriction increased quickly, especially at low magnetic field in the alloy with x=0.65 due to separation of rich rare earth phases on the surface of the alloy.

Effect of Ho-doping on photocatalytic activity of nanosized TiO 2 catalyst

Ho-doped TiO 2 nanoparticles with higher photocatalytic activity were prepared by an acid-catalyzed sol-gel method. The photocatalytic decomposition of methyl orange in aqueous solution was used as a probe reaction to evaluate their photocatalytic activities. The effects of Ho doping on the crystallite sizes, crystal pattern, surface composition, and optical property of the catalysts were investigated by means of techniques such as X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Diffuse Reflectance UV-Vis Spectroscopy (UV-Vis DRS), Fourier Transform Infrared (FT-IR), and Photo-Luminiscence (PL) spectra. Moreover, the modification mechanism of Ho doping was also discussed. The results showed that Ho doping could inhibit phase transformation from anatase to rutile, suppress the growth of TiO 2 grains, cause blue shift of the absorption spectrum edge, accelerate surface hydroxylation, and enhance the separation efficiency of photoinduced electron-hole pairs, which resulted in a significant improvement in the photoreactivity of Ho-doped TiO 2. Among them, the Ho-doped TiO 2 calcined at 500°C achieved the highest photocatalytic activity.

The effect of Ho doping on the microstructure and optical properties of Ba 0.65Sr 0.35TiO 3 thin films

Ba 0.65Sr 0.35TiO 3 (BST) thin films doped with holmium were prepared on silicon and fused quartz substrates by a modified sol–gel technique. The microstructures of BST films were characterized by atomic force microscopy (AFM) and X-ray diffraction (XRD). The results showed that 3 mol% Ho-doped BST has the largest grain size and surface root-mean square roughness. The transmission spectra of Ho-doped BST films were measured by spectrophotometer. The refractive index and thickness of 1 mol% Ho-doped BST film was calculated using envelope method from the transmission spectra. It showed that the refractive index increased from 1.94 to 2.09 as wavelength decreased from 700 nm to 400 nm, which was smaller than pure BST thin films we have reported. The average oscillator strength and wavelength were estimated using a Sellmeir-type dispersion equation. These results show the potential of using Ho-doped BST thin films as an electro-optical novel material.

The effect of Ho-doping and Ho-adding on electronic transport and magnetic properties of La0.67Ca0.33MnO3

The effect of Ho-doping and Ho-adding on the electronic transport and magnetic properties of melt-processed La0.67Ca0.33MnO3 (LCMO) is investigated by resistivity and AC susceptibility measurement. For Ho-addition of 1mol% LCMO sample (Ho-LCM), its magnetic transition temperature Tc and metal–insulator (M–I) transition temperature Tp are enhanced about 70K compared with Ho-free LCMO sample. However, for Ho-doping of 3mol% LCMO sample (Ho-doping LCM), both Tc and Tp are reduced about 35K. We give a reasonable explanation in terms of structural changes (bond distance and bond angle) gained from the XRD refinement. The nanoscale Ho distribution is consistent with the magnetic inhomogeneity induced MR which is verified by the double peaks in AC susceptibility χ″ and the drop of χ′(T) curve below Tc. The mechanism of transport of all the samples is discussed.