Holmium Concentration Research Articles

Associations of maternal urinary rare earth elements individually and in mixtures with neonatal size at birth

Prenatal rare earth elements (REEs) exposure is linked to unfavorable health consequences. Epidemiologic research on repeated measurements of REEs during gestation correlated with fetal growth is exiguous. Until now, few studies have characterized exposure characteristics of REEs in pregnant women. We aimed to ascertain the characteristics and predictors of REEs exposure over three trimesters among pregnant women and examine the possible effects of prenatal REEs exposure on size at birth. Urinary REEs concentrations exhibited considerable within-subject variation with intraclass correlation coefficients ranging from 0.16 to 0.58. Maternal age, household income, gestational weight gain, passive smoking during pregnancy, parity, and neonatal gender were associated with maternal urinary REEs concentrations. Elevated maternal urinary holmium and thulium concentrations in the 3rd trimester were significantly related to reductions in birth weight. Weighted quantile sum (WQS) regression model identified that urinary REEs mixture in the 3rd trimester were negatively related to birth weight (WQSREEs β = −26.22; 95% confidence interval [CI]: −47.62, −4.82), with holmium (40%) and thulium (24%) receiving the highest weights. Male infants received the most weight (>50%) related to decreased birth weight. This study revealed a significant association between individual and mixture REE exposure in late pregnancy with a reduction in birth weight.

Biochemical indicators of the lipid metabolism in workers involved in the processing of raw materials and production of rare metal products

Introduction. In recent years, the use of rare earth elements has been expanding in various innovative research and high-tech industries, which leads to an increase in the volume of their extraction and processing and makes it possible to develop a negative impact on the health of workers under conditions of long-term industrial exposure to rare earth elements with the air of the working area.
 The purpose of the work is to study and evaluate the deviations of the biochemical parameters of the lipid spectrum in workers, due to the chemical factors of the technological process of processing raw materials and production of rare metal products.
 Materials and methods. The study and evaluation of the content of rare earth elements in the blood of workers, the study of biochemical parameters, statistical analysis, modelling of cause-and-effect relationships were carried out.
 Results. Workers exposed to rare-earth elements with the air of the working area (100% of workplaces) showed increased concentrations of holmium, dysprosium, yttrium, neodymium, niobium and terbium in the blood from 1.5 to 2.5 times compared to similar indicators in workers who were not associated with technological process. Elevated levels of total cholesterol, VLDL and triglycerides in blood serum, a decrease in the total antioxidant activity of blood plasma in workers relative to the physiological norm and similar indicators in the comparison group were established. A significant relationship of the identified deviations with an increased blood concentration of niobium, dysprosium and holmium has been proven.
 Limitations. The study took into account the aerogenic inhalation effect of rare earth elements on the health of workers involved in the processing of raw materials and production of rare metal products. 
 Conclusion. Long-term inhalation exposure to rare earth elements contained in the air of the working area caused changes in biochemical parameters, reflecting the depletion of antioxidant defense resources, inducing disorders of lipid metabolism. The identified negative effects in workers can lead to pro-atherogenic vascular inflammation under conditions of continuing industrial exposure. The obtained results should be taken into account for the development of recommendations aimed at minimizing the negative consequences of the impact of the studied chemical factors of the labour process on the health of workers.

TL defect center analysis and radiation shielding phenomenon In Ho3+: Pb(YB)2O7 composite glasses

The aim of the ongoing research was to create resources that are mechanically durable, thermally luminous, and radiation-shielding. In this manner, we intended to synthesize lead borate glasses containing functional groups for yttrium and holmium. Ho2O3 doped glasses, which are typically used for luminescent purposes, will also be used to investigate the thermoluminescence characteristics under gamma radiation. XRD, SEM, EDX, and DTA techniques are used to examine the samples’ structure, chemical analysis, and thermal characteristics. To assess the samples’ micro-hardness, the test sample’s ultrasonic velocities are measured. The mass attenuation coefficient and order of radiation protection ability are shown by the radiation shielding characteristics of samples. It should be highlighted that Holmium ions alone are responsible for the variations in the shielding behavior of glasses. The TL characteristics of the samples were examined at gamma irradiation doses of 0, 10, and 25 kGy. Irradiation increases the TL Intensities that have been observed. The findings show that Ho2O3 is the only factor contributing to the TL phenomenon, and test samples exhibit substantial TL activity. Additionally, samples were examined using the DTA technique for changes in thermal stability. This also implies that changes in thermal stability are solely dependent on holmium concentration. Overall, the results showed that YPBH glasses are effective TL materials and strong radiation shielding resources with low thickness values.

Structural, Optical and Dielectric Properties of Holmium-Doped Nickel-Cadmium Ferrite Nanoparticles Synthesized by Sol-Gel Auto-Combustion Method

Nanoparticles where holmium was substituted with nickel-cadmium Ni0.5Cd0.5HoxFe2-xO4 (X = 0, 0.02, and 0.04) ferrites were synthesized through a sol-gel auto-combustion process to reveal their structural and physical properties. The synthesized nanoparticles were characterized using X-ray diffraction (XRD), a scanning electron microscope (SEM), Fourier transform infrared ray (FTIR) spectroscopy, and impedance spectroscopy techniques. XRD revealed the formation of the cubic crystal structure had a preferential orientation along (311). By including holmium, the lattice constant was reduced, while the average crystallite size was increased. SEM analysis revealed that the nanoparticles exhibited regular shapes, and the average grain size increased with the holmium content. FTIR spectroscopy determined that all the organic and inorganic materials had an absorption range of 400 to 4000 cm−1. The dielectric properties were measured between the frequency ranges of 1 kHz and 2 MHz. This shows that the tangent loss and the dielectric constant were raised when the concentration of holmium was increased.

Structural, impedance, and photoluminescence properties of Ho3+ substituted Na0·5Bi0·5TiO3

Complex impedance and photoluminescence properties have been investigated in Na0.5 Bi(1-x) HoxTiO3 x = 0, 0.5, 1, 2 and 3 mol %. The observation of semicircle in the higher temperature regime from the Nyquist plots confirms the Debye type relaxation. Overlapping of normalized Z″ and M″ peaks suggested the long-range relaxation of charge carriers. The grain resistance (Rg) decreased with temperature. The improved insulating character was found for a small concentration (0.5 mol %) of holmium substituted NBT. Additionally, photoluminescence emission peaks associated with the transitions in Ho3+ ions were observed in the visible range. Quenching in photoluminescence intensities was observed in the higher composition (3 mol % Ho3+ substituted NBT) which we surmise as due to the collective impact of concentration quenching and the emergence of higher symmetric orthorhombic phase (Pbnm) within lower symmetric (R3c + Cc) phase.

High efficiency holmium-doped triple-clad fiber laser at 2120 nm

We developed a new holmium-doped triple-clad fiber (Ho-3CF), reducing the clad diameter to improve the overlap between pump and doped-core, and the holmium concentration to reduce the influence of ion clustering on the laser efficiency. We illustrate here the performance of this fiber in a laser oscillator configuration. The laser emission is centered at 2.12&#x00A0;m by a fiber Bragg grating, and the active fiber is pumped in the clad by a 1.94&#x00A0;m thulium-doped fiber laser. The slope efficiency reaches 73&#x00A0;&#x0025; with respect to absorbed power (60&#x0025; considering coupled power), for a maximum signal power of 62&#x00A0;W delivered on a quasi single spatial mode (M<inline-formula><tex-math notation="LaTeX">$^{2}$</tex-math></inline-formula>=1.2). To the best of our knowledge, this slope efficiency is the highest reported for a high power clad-pumped fiber laser emitting at a wavelength higher than 2.1&#x00A0;m. We also analyze experimentally the impact of the pump Numerical Aperture (NA), at the input of the Ho-3CF, on the laser efficiency. Finally, we use our numerical simulation to comment on the best choice of pump wavelength.

Fabrication and luminescent properties of holmium doped Y2Zr2O7 transparent ceramics as new type laser material

Via a vacuum sintering method, highly transparent Ho: Y 2 Zr 2 O 7 ceramics with different holmium doping concentrations were successfully fabricated for the first time. Y 1.99 Ho 0.01 Zr 2 O 7 and Y 1.98 Ho 0.02 Zr 2 O 7 transparent ceramics exhibit the highest in-line transmittance at 72% in the visible (Vis) region and over 75% in the near infrared (NIR) region. The microstructure and crystal structure of Ho: Y 2 Zr 2 O 7 transparent ceramics were fully investigated by SEM and XRD measurements. Photoluminescence spectra demonstrated that Ho: Y 2 Zr 2 O 7 ceramics can be effectively excited at 376 nm and 460 nm. Strong green (centered at 551 nm) and NIR (centered at 1111 nm) emissions were observed in the downshifting (DS) luminescence. Meanwhile, same green emissions have been observed in the upconversion (UC) luminescence. The luminescence decay curves have also been studied, demonstrating that the longest average fluorescence lifetime of Ho: Y 2 Zr 2 O 7 transparent ceramics reaches 48 μs. Combined with the high temperature resistance and good mechanical strength of Y 2 Zr 2 O 7 transparent ceramics, these results suggest that Ho 3+ : Y 2 Zr 2 O 7 transparent ceramics are able to generates both down and up converted fluorescence. (1) Highly transparent Ho: Y 2 Zr 2 O 7 ceramics was fabricated via vacuum sintering method for the first time. (2) Different holmium concentration was studied and fluorescence quenching at 2% mol was observed. (3) High intensity Up/Down-conversion and shorter decay time were investigated, indicating that Ho: Y 2 Zr 2 O 7 generates both down and up converted fluorescence.

Development of an MRI-Guided Approach to Selective Internal Radiation Therapy Using Holmium-166 Microspheres.

Simple SummarySelective internal radiation therapy (SIRT) is a treatment for patients with liver cancer that involves the injection of radioactive microspheres into the liver artery. For a successful treatment, it is important that tumours are adequately covered with these microspheres; however, there is currently no method to assess this intraoperatively. As holmium microspheres are paramagnetic, MRI can be used to visualize the holmium deposition directly after administration, and possibly to adapt the treatment if necessary. In order to exploit this advantage and provide a personally optimized approach to SIRT, the administration could ideally be performed within a clinical MRI scanner. It is, however, unclear whether all materials (catheters, administration device) used during the procedure are safe for use in the MRI suite. Additionally, we explore the capability of MRI to visualize the microspheres in near real-time during injection, which would be a requirement for successful MRI-guided treatment. We further illustrate our findings with an initial patient case.Selective internal radiation therapy (SIRT) is a treatment modality for liver tumours during which radioactive microspheres are injected into the hepatic arterial tree. Holmium-166 (166Ho) microspheres used for SIRT can be visualized and quantified with MRI, potentially allowing for MRI guidance during SIRT. The purpose of this study was to investigate the MRI compatibility of two angiography catheters and a microcatheter typically used for SIRT, and to explore the detectability of 166Ho microspheres in a flow phantom using near real-time MRI. MR safety tests were performed at a 3 T MRI system according to American Society for Testing of Materials standard test methods. To assess the near real-time detectability of 166Ho microspheres, a flow phantom was placed in the MRI bore and perfused using a peristaltic pump, simulating the flow in the hepatic artery. Dynamic MR imaging was performed using a 2D FLASH sequence during injection of different concentrations of 166Ho microspheres. In the safety assessment, no significant heating (ΔTmax 0.7 °C) was found in any catheter, and no magnetic interaction was found in two out of three of the used catheters. Near real-time MRI visualization of 166Ho microsphere administration was feasible and depended on holmium concentration and vascular flow speed. Finally, we demonstrate preliminary imaging examples on the in vivo catheter visibility and near real-time imaging during 166Ho microsphere administration in an initial patient case treated with SIRT in a clinical 3 T MRI. These results support additional research to establish the feasibility and safety of this procedure in vivo and enable the further development of a personalized MRI-guided approach to SIRT.

Investigation on structural and thermoluminescence properties of Ho3+doped SrB4O7 phosphor for dosimetry applications

A series of tissue equivalent novel Sr(1-x)B4O7:Hox (0 ≤ x ≤ 0.5 mol%) phosphors have been synthesized via solid state diffusion to investigate their structural and Thermoluminescence features. The rietveld refinement of XRD data confirms pure phase formation with an orthorhombic crystal structure. FTIR and Raman spectroscopy have been used to examine the vibration characteristics and bonding among each constituent of material. The analysis detected bending vibrations of bridging oxygen's within B-O-B bonds in BO3 trigonals, alongwith stretching vibrations of [BO4] tetrahedral. SEM was used to inquire the surface morphology as well as to record EDX patterns for authentication of the elemental composition in all the samples. The microphosphors possess a dense structure with irregularly shaped grains with an average grain size of 1.36–1.45 µm. The TL glow curves have been recorded to evaluate the dosimetric properties of γ-exposed phosphors i.e. dose response, fading and reproducibility. Doped samples exhibit higher TL sensitivity as compared to pure samples. The critical holmium concentration for TL was found to be 0.5 mol%. Fading was examined and the TL intensity of the predominant dosimetric TL Peak of SB3 sample was determined to be a -12% decline after 15 days. Repetitive analysis demonstrates that SrB4O7 have high reproducibility. The phosphors exhibit a linear dose response and good reproducibility, with a standard deviation of ∼2%. The trapping parameters (viz. E, b and s) have been computed using PS, IR and Ilich methods. The dosimetric attributes of the novel fabricated phosphors acknowledge their adequacy for dosimetry applications.

The Optical Performance of Holmium Oxide Doped Tellurite Glass for Potential Optical Fiber

Borotellurite glass had been widely applied in the field of optical communications and devices. In this work, holmium oxides doped borotellurite glass had been successfully fabricated via conventional melt-quenched technique. The structural properties of holmium doped tellurite glass were found using x-ray diffraction (XRD) method. The nonexistence of sharp peaks in XRD pattern shows that the inclusion of holmium tellurite glass leads to the formation long range of disorderness. The optical properties of the glass system such as refractive index and optical band gap energy are investigated using UV-Vis spectrophotometer. The value of refractive index is found in nonlinear trend along with holmium oxides concentration. It is found that the refractive index is more than 2 at 0.01, 0.03 and 0.04 of holmium concentrations. The optical band gap energy was found in similar trend with refractive index which is in nonlinear pattern.

A novel IR-transparent Ho3+:Y2O3–MgO nanocomposite ceramics for potential laser applications

The work is devoted to obtaining of transparent nanocomposite materials as low loss, highly thermally conductive materials for potential laser applications. We report Ho3+:Y2O3–MgO nanocomposite ceramics with excellent mechanical and optical properties by combining glycine-nitrate process and spark plasma sintering. Morphology, structural-phase state, infrared transmittance and luminescence depending on the holmium concentration (0–12 at.%) were studied for the first time. It was found that optical transmittance reaches 75%@6000 nm for 3 at.% Ho3+:Y2O3–MgO ceramics. The absorption cross-section at 1931 nm and the emission cross-section at 2118 nm were determined to be σabs = 0.51 × 10−20 cm2 and σem = 0.29 × 10−20 cm2, respectively. Based on the testing results of luminescent characteristics it was demonstrated that Ho3+:Y2O3–MgO nanocomposite is a promising material for high-power eye-safe lasers operating in the 2 μm wavelength range.

Quantitative dual-energy CT material decomposition of holmium microspheres: local concentration determination evaluated in phantoms and a rabbit tumor model

ObjectivesThe purpose of this study was to assess the feasibility of dual-energy CT-based material decomposition using dual-X-ray spectra information to determine local concentrations of holmium microspheres in phantoms and in an animal model.Materials and methodsA spectral calibration phantom with a solution containing 10 mg/mL holmium and various tube settings was scanned using a third-generation dual-energy CT scanner to depict an energy-dependent and material-dependent enhancement vectors. A serial dilution of holmium (microspheres) was quantified by spectral material decomposition and compared with known holmium concentrations. Subsequently, the feasibility of the spectral material decomposition was demonstrated in situ in three euthanized rabbits with injected (radioactive) holmium microspheres.ResultsThe measured CT values of the holmium solutions scale linearly to all measured concentrations and tube settings (R2 = 1.00). Material decomposition based on CT acquisitions using the tube voltage combinations of 80/150 Sn kV or 100/150 Sn kV allow the most accurate quantifications for concentrations down to 0.125 mg/mL holmium.ConclusionDual-energy CT facilitates image-based material decomposition to detect and quantify holmium microspheres in phantoms and rabbits.Key Points• Quantification of holmium concentrations based on dual-energy CT is obtained with good accuracy.• The optimal tube-voltage pairs for quantifying holmium were 80/150 Sn kV and 100/150 Sn kV using a third-generation dual-source CT system.• Quantification of accumulated holmium facilitates the assessment of local dosimetry for radiation therapies.

Thermophysical Properties of Solid Yttrium–Holmium Solutions in the Temperature Range from Room Temperature to 1400 K

The thermophysical properties (thermal diffusivity, specific heat, and thermal conductivity) and resistance of solid solutions (alloys) of rare-earth metals (yttrium and holmium) have been experimentally studied. It is established that, on the whole, these properties obey the same laws as pure rare-earth metals. Heat transfer in Y–Ho alloys at the considered temperatures is mainly performed by electrons as well. The existing quantitative differences between the properties are due to the different influences of the different mechanisms of carrier (electron) scattering. A procedure to separate the contributions to electron scattering based on the Mott model is considered. The roles of phonon-, magnetic-, and impurity-scattering mechanisms are determined. It is established that the magnetic-scattering intensity monotonically decreases upon heating and with a decrease in the holmium concentration. Nordheim’s rule is valid for impurity scattering, which indicates stability of the energy spectrum structure of collective alloy electrons.

Nanoparticle and Solution Doping for Efficient Holmium Fiber Lasers

Efficient holmium fiber lasers have been studied as attractive laser sources operating around 2.1 μm. We report on holmium-doped silica fibers prepared by the modified chemical vapor deposition in combination with either a solution-doping method or a nanoparticle-doping method. A set of 15 fibers with various compositions was characterized and compared with respect to their fluorescence lifetime, laser slope efficiency and laser threshold. This set of fibers in wide concentration ranges allowed us to assess reliably the influence of material composition and the influence of doping method. The best-performance fibers exhibited slope efficiency 83.1%, laser threshold 155 mW and a record value of upper laser level lifetime of 1.35 ms. These results were achieved in fibers with holmium concentration lower than 800 molar ppm and Al/Ho molar ratio greater than 70. Significant differences between fibers prepared by solution doping and nanoparticle doping were not observed. The behavior of Al2O3 nanoparticles during fiber preparation is discussed in details.

Formation of nano-scale composite anodic films on aluminium-holmium alloys

This study demonstrates the formation of barrier-type anodic films in a phosphate buffer (pH 8.4) on thermally evaporated aluminium-holmium alloys covering a 2.0–12.0 at.% Ho compositional spread. Scanning x-ray diffraction and scanning electron microscopy reveal that structure and morphology of the parent alloys library drastically change above 6.5 at.% Ho. Anodic films were formed when the as-evaporated alloys were stepwise anodized potentiodynamically to a maximum of 10 V in phosphate buffer regardless of film composition and morphology. Simultaneous in-situ electrochemical impedance spectroscopy discloses a good co-relation between film thickness and formation factor with the composition and morphology of parent alloys, suggesting a strong influence of holmium concentration on the structure, morphology of parent alloys as well as on the dielectric properties of resulting anodic films. Inductively coupled plasma optical emission spectroscopy measurements allowed a quantitative determination of the dissolved species during anodization.

OA085] CT Quantification of holmium distribution for absorbed dose calculation in a context of microbrachytherapy

Purpose Holmium 166 ( 166 Ho) is a potential candidate for internal radiotherapy due to high-energy beta radiation (1.77 and 1.85 MeV) and gamma ray (80.6 keV) adapted to SPECT imaging albeit with poor spatial resolution (cm). The spatial resolution at which activity distribution is determined impacts the absorbed dose calculation algorithm that needs to be implemented: For example, SPECT spatial resolution will often lead to the Local Energy Deposition (LED) approximation. In this study, we investigated the potential of CT for holmium quantification, and compared various absorbed dose calculation algorithms in a context of micro-brachytherapy. Methods For CT calibration, acquisitions were performed on a General Electric BrightSpeed 16 using a CIRS 62 phantom with known holmium concentration in order to get a calibration curve. We then assessed holmium concentration in brain tumours implanted in Yucatan minipigs treated by 166 Ho microbrachytherapy. Acquisition parameters were as follows: voltage = 140 kV; reconstruction filter B31s, matrix size: 512 × 512; pixel size: 0.488 × 0.488 mm 2 ; slice thickness = 0.625 mm. Holmium segmentation was based-on pre and post injection CT image subtraction. From the CT calibration curve, and with a prior knowledge of 166 Ho specific activity, it was possible to get a 3D activity distribution. Different absorbed dose computation approaches were implemented: Local Energy Deposition (LED), superposition/convolution of dose-point kernels assuming homogenous or heterogeneous media, and Monte Carlo modelling (GATE) taken as the reference. Gamma-index criteria (0.1%, 0.5 mm) were used to compare approaches. Results The LED approach was clearly not appropriated due to 166 Ho range vs. CT resolution (0.15% passing rate according to the gamma-index criteria). Homogenous and heterogeneous convolution/superposition approaches provided 78% passing rate in a situation of homogenous soft tissues, compared to GATE. Discrepancies were mainly visible in a situation of heterogeneous densities. Conclusions CT-based holmium quantification can provide relevant density information with good spatial resolution (as compared to SPECT imaging), broadening the possibilities for absorbed dose calculation algorithms. This work was partially sponsored by BPI-France under the scope of the Industrial Strategic Innovation project (projet d’Innovation Strategique Industrielle) “TheraneaM.

Synthesis and characterizations of Ho2O3 modified SrBi2Nb2O9 ceramics

SrBi2-xHoxNb2O9 (0 ≤ x ≤ 0.5) ceramics were prepared through the conventional solid state route. The materials have been characterized by XRD, FTIR and SEM. All compounds were pure and well crystallized. In FTIR spectroscopy, the spectral patterns of the crystal structures of these polyphases are unique and smoothly different from each other. The grains were prone to become spherical with increasing x. Dielectric and electrical properties of these materials as a function of temperature at different frequencies have been carried out. The dielectric constant and dielectric loss were found to decrease with an increase of the holmium concentration at room temperature. Reaching up to x = 0.4 and x = 0.5, the diffusivity increases, leading to the occurrence of relaxor behavior. 20–30 at.% Ho doping on the Bi-site can fill up the oxygen vacancies and decrease the AC conductivity. However, at higher doping levels greater than 40% holmium oxide, the AC conductivity is found to increase.

Optical and Physical Investigations of Lanthanum Bismuth Borate glasses doped with Ho2O3

Holmium doped 10La2O3-15Bi2O3-(75-x) B2O3 (Ho3+: LBB) glasses have been prepared by melt quench technique and the impact of holmium ions concentration on optical and physical properties of present glasses have been examined. Ho3+ dependent density, molar volume, refractive index, rare earth ion concentration, polaron radius, inter ionic distance, field strength and energy band gap are calculated and tabulated. Amorphous nature of the all glasses has been confirmed by XRD patterns. The room temperature (RT) Uv-Vis absorption spectrum doped with 1 mol% of Ho2O3 exhibit eight prominent bands centred at 895, 641, 537, 486, 472, 467, 451 and 416 due to transition between ground state to various excited states. The results show that, the density is increases and molar volume of the glasses is decreases with an increase in Ho2O3 concentration and consequently generate more non-bridging oxygen (NBOs) in the glass matrix. The Urbach energy is increases with holmium concentration which exemplifies the degree of disorder present in the LBB glasses. The considerable increase in field strength observed in present glasses is attributed to occurrence of strong bridge between Ho3+ and B- ions and this strong bridge is possibly due to the displacement between Ho3+ and oxygen atoms which are generated from the conversion BO3–BO4 units.

Microstructure, lattice strain, magnetic and magnetostriction properties of holmium substituted cobalt ferrites obtained by co-precipitation method

The CoHoxFe2-xO4 (x = 0.00, 0.05, 0.1, 0.15, 0.2) samples were synthesized by chemical co-precipitation technique. The structural properties were studied using X-ray diffraction (XRD). XRD data reveal formation of single cubic spinel phase for the samples having lower concentration of holmium substitution namely x = 0.0, 0.05 and 0.10, However, at higher concentrations, x = 0.15 and 0.2 few extra diffraction lines belonging to HoFeO3 were observed indicating solubility limit of holmium in the CoFe2O4 lattice. Williamson – Hall plot was used to determine strain in the samples. Microstructural studies carried out using Scanning Electron Microscopy (SEM) depict significant changes in microstructure with increase in holmium concentration. Microstructure of un-substituted cobalt ferrite sample was found to be very compact and grain growth was further found to be restricted with increase in holmium concentration. DC magnetization recorded using Vibrating Sample Magnetometer (VSM) at room temperature indicates decrease in saturation magnetization with increase in Holmium concentration, which is correlated with the weakening of A-B exchange interactions. Comparatively high values of coercivity and retentivity are obtained for holmium concentration with x = 0.15. Magnetostriction measurements were carried out for two different orientations of strain gauge fixed on plane surface of sample with parallel and perpendicular orientation with respect to direction of external magnetic field. For un-substituted cobalt ferrite sample, maximum value of magnetostriction was found to be −228 ppm at 3.5 kG magnetic field. This suggests its application in actuator. Further, effect of holmium substitution on magnetic and magnetostrictive properties has been analyzed.

Structural and optical properties of α-Fe2O3 nanoparticles, influence by holmium ions

α-Fe2O3 and α-Fe2O3 doped with different concentration of holmium ions were synthesized by a simple sol-gel method. The XRD data confirmed the hexagonal structure of α-Fe2O3 for un-doped and holmium doped samples. The crystallite size was found to be decreasing with increasing holmium concentration. The amount of holmium was quantified using an EDS, which shows an increase in holmium quantity as concentration increases. The UV–Vis measurement shows an absorption edge around 570nm. The band gap was estimated using the Kubelka-Munk relation and it was found to be fluctuating between 1.94eV and 2.04eV. The PL spectra confirmed the effect of holmium ions on luminescence properties of α-Fe2O3 which showed a maximum intensity at 0.1mol% Holmium, and quenching as the concentration is increased from 0.3mol% to 0.9mol%.