Gadolinium Molybdate Research Articles

Probing the luminescence behavior of Dy3+/Eu3+ co-doped gadolinium molybdate phosphors under the impact of swift heavy ions

Probing the luminescence behavior of Dy3+/Eu3+ co-doped gadolinium molybdate phosphors under the impact of swift heavy ions

A disposable tartrazine sensor fabricated with a synchronously activated nanocomposite comprising gadolinium molybdate nanoflowers anchored on functionalized carbon nanofibers

Preparation and fabrication of a Gd2MoO6/f-CNF nanocomposite for the electro-oxidation of TRZ in food samples.

Facile synthesis of gadolinium molybdate embedded reduced graphene oxide composite for ultrasensitive detection of hazardous metol

Research in rare-earth metal molybdates has received great interest in several applications owing to their specific properties such as various oxidation states, magnetic, and electrical properties. Among them, gadolinium molybdate (GdM) has excellent mechanical, electrical, thermal, and chemical properties. In this study, we synthesized GdM with carbonaceous material–reduced graphene oxide (RGO) due to the properties such as electrical transport properties, large surface area, and mechanical flexibility. Thus, GdM/RGO nanocomposite is used for the electrochemical detection of metol (ML). The synthesized GdM/RGO was characterized by various physicochemical techniques. Then the electrochemical property was examined by CV and DPV technique which gives an excellent electrical property towards highly harmful organic pollutant ML. Additionally, the GdM/RGO sensor has a 3.9 nM low detection limit (LOD) and linear ranges of 0.01 to 1792 µM for ML determination, under optimized experimental conditions. As a further assessment, river water and tap water was used as a real sample for GdMoO4 synthesis, and reasonable recovery results were obtained.

Temperature-driven complex dielectric and polaron-hopping mediated electrical conduction in aurivillius Gd2MoO6

In this work, aurivillius gadolinium molybdate (Gd2MoO6) was synthesized by the conventional solid-state route which was accompanied by cutting-edge characterization i.e., structural, and electrical, to give insight into the material characteristics required for possible high-temperature applications. The single-phase crystalline nature with monoclinic symmetry (C2/c, Space group-15) of Gd2MoO6 was confirmed by the X-ray diffraction (XRD) pattern. The average particle size was obtained to be ∼0.495 µm. The electrical conductivity and dielectric properties of a Gd2MoO6 plate capacitor were investigated in the frequency range between 10 Hz and 1 MHz and temperature from 473 to 773 K. A high dielectric constant (ε') of ∼3272 and low dielectric loss (δ) of ∼200 was observed at the low frequency and high-temperature regions, respectively. The Maxwell–Wagner interfacial polarization was found to be responsible for the decrease of the dielectric constant with increasing frequency. The behavior with the temperature of the frequency exponent (n) from the fitted conductivity spectra by Jonscher power law corresponds to the non-overlapping small polaron tunneling model between 473–673 K and correlated barrier hopping model at/over 673 K. The non-exponential Kohlrausch Williams-Watts function was introduced to fit the imaginary modulus (M′′) spectra and the activation energy was obtained to be 0.81 eV for grain and 0.94 eV for grain boundary conduction. The Nyquist plots(Z′vs.Z′′) differentiate the grain and grain boundary contribution and were fitted with the combinations of resistance (R), capacitance (C), and constant phase element (Q) in an equivalent circuit model(RC)(RCQ). Typical negative temperature coefficient of resistance behaviors of Gd2MoO6 suggest its possible application as thermistors in modern electronics circuits.

New insight into lithium-containing ternary compound based on barium gadolinium molybdate

In this work, a part of BaMoO4-Gd2(MoO4)3–Li2MoO4 ternary system has been investigated. It has been shown that the ternary compounds formed in the system are solid solutions based on BaGd2(MoO4)4 with 0–90% filling of cationic vacancies as the lithium content in the solid solution increases. XRD and Raman studies have been carried out, and the possibilities of growing solid solution single crystals of various compositions have been determined. Neodymium doped solid solution single crystals has been grown and optical absorption spectra has been analysed.

3D walnut-like rare-earth gadolinium molybdate encapsulated with thermo-responsive hydrogel for sensitive electrochemical detection of anticancer drug Niftolide in human urine

Prostate cancer is ranked as the second most common type of cancer in men and has a high mortality rate. Niftolide (NIFT), a non-steroidal antiandrogen drug, has been extensively used in the treatment of prostate cancer; however, its improper and excessive use can lead to unwanted side effects and complications to the body. In this study, we synthesized a novel rare-earth gadolinium molybdate encapsulated with thermo-responsive hydrogel composite (PNIPAM/GdMo) using a simple precipitation technique for electro-catalytic detection of NIFT in human urine samples. Urea (NH2CONH2) and Ethylene glycol (EG; (CH2OH)2) used in the synthesis process exhibited a bifunctional behavior by simultaneously acting as a reducing agent and enhancing the 3D morphological structure. In addition, the encapsulation of the PNIPAM with GdMo particles showed a significant synergic effect and a high surface area. The morphological, structural, chemical components, and electro-catalytic properties of the composite are studied by various analytical and electro-catalytic techniques. The electro-catalytic studies indicated a significant improvement in the current response of the sensor at 40 °C as compared to 20 °C, which makes it a temperature-enabled reversible sensor. The proposed sensor exhibited excellent limit of detection (LOD) of 5 nM, linear range (LR) of 0.01–4, 8 − 400 µM, and sensitivity of 1.1858 µA µM−1 cm−2. Moreover, the anti-interference ability, reproducibility, and stability reinforced the practical applicability of the proposed sensor for the electro-catalytic detection of NIFT quantity in human urine samples. The sensor showed an excellent recovery rate with RSD of less than 3%, which authenticates its potential for real-time applications.

Ultra-trace detection of caffeine and theophylline with high sensitivity and selectivity using Gd2(MoO4)3 nanosheets

In this study, gadolinium molybdate, Gd2(MoO4)3 (Gam) nanosheets have been substantially synthesized using a hydrothermal method with varying reaction temperatures. PXRD, XPS, and HR-TEM confirmed the crystal phase and morphology of Gam nanosheets. According to CV, LSV, and EIS techniques, Gam (synthesized at 150 ℃) modified GCE possesses excellent electrochemical properties and further has been used for caffeine and theophylline detection. The limit of detection of caffeine was found to be 4.1 nM with a linear range of 0.01 – 0.1 μM and 0.2 – 1.6 μM. Limit of detection of theophylline was calculated to be 11.9 nM with a linear range of 0.03 – 1.5 μM and 2.0 – 4.5 μM. Gam modified GCE was applied for caffeine and theophylline detection in green tea leaves (GS-1) and coca (CS-2) samples and interestingly found capable for caffeine detection without spiking. After spiking, recoveries of caffeine and theophylline in GS-1 were achieved 100.6 – 101.7% and 102.57–105.21% respectively. In CS-2 the recoveries for caffeine and theophylline were found to be 98.3 – 101.8% and 97 – 99.33% respectively. The excellent long-term stability, recyclability, and real sample analysis validated the sensor for biological as well as pharmaceutical samples diagnosis.

Observation of cation-specific critical behavior at the improper ferroelectric phase transition in Gd2(MoO4)3

Gadolinium molybdate is a classical example of an improper ferroelectric and ferroelastic material. It is established that the spontaneous polarization arises as a secondary effect, induced by a structural instability in the paraelectric phase, which leads to a unit cell doubling and the formation of a polar axis. However, previous x-ray diffraction (XRD) studies on gadolinium molybdate have been restricted by the limited ability to include a wide $2\ensuremath{\theta}$ range in the analysis, and thus, at atomic scale, much remains to be explored. By applying temperature-dependent XRD, we observe the transition from the paraelectric tetragonal phase to the orthorhombic ferroelectric phase. The ferroelastic strain is calculated based on the thermal evolution of the lattice parameters, and Rietveld refinement of the temperature-dependent data reveals that the displacement of different cations follows different critical behavior, providing insight into the structural changes that drive the improper ferroelectricity in gadolinium molybdate.

New Insight into Lithium-Containing Ternary Compound Based on Barium Gadolinium Molybdate

New Insight into Lithium-Containing Ternary Compound Based on Barium Gadolinium Molybdate

Gadolinium molybdate decorated graphitic carbon nitride composite: highly visualized detection of nitrofurazone in water samples.

In this work, a graphitic carbon nitride/gadolinium molybdate (g-C3N4/Gd2MoO6) composite manufactured glassy carbon electrode (GCE) was used to detect nitrofurazone (NFZ) at the trace level. A quick and inexpensive electrochemical sensor for NFZ analysis is described in this paper. The material structure and properties were determined by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and transmission electron microscopy. The GCE/g-C3N4/Gd2MoO6 electrode was studied using cyclic voltammetry and amperometry. The electrocatalytic studies of the GCE/g-C3N4/Gd2MoO6 electrode showed significantly improved detection of NFZ. The electrocatalytic studies of the GCE/g-C3N4/Gd2MoO6 electrode was significantly improved for the detection of NFZ than bare GCE, GCE/g-C3N4, and GCE/Gd2MoO6 modified electrodes. The linear response and the detection limit of NFZ were 0.006 μM (S/N = 3) and 0.02-2000 μM, respectively. The electrode sensitivity was identified as 2.057 μA μM-1 cm-2 under ideal experimental conditions. The modified electrode was able to detect NFZ even when there were 500-fold as many interfering ions present. The practical applicability of the electrode was tested in a variety of water samples, with satisfactory results. Overall, the NFZ sensor demonstrated satisfactory repeatability, stability, and reproducibility. Meanwhile, it has proven to be a reliable, stable, and practical platform for the analysis of NFZ in various water samples, with acceptable recoveries.

Dual-emissive Eu3+, Tb3+ co-doped Gd2(MoO4)3 phosphor for optical thermometry application

Ratiometric fluorescent sensing materials based on dual-emissive luminescent centers have been widely researched due to their highly stable self-calibrating monitoring performance. In this work, Eu3+, Tb3+ co-doped gadolinium molybdate [Gd2(MoO4)3] phosphors were successfully prepared through a facile precipitation and a following heat treatment process. Dual-emissive Gd2(MoO4)3: Eu3+, Tb3+ phosphor showed characteristic emission peaks at 592, 617, and 703 nm corresponding to the transitions of 5D0–7F1, 5D0–7F2 and 5D0–7F4 for Eu3+ ions, and the other emissions at 488 and 543 nm were ascribed to 5D4–7F6 and 5D4–7F5 transitions for Tb3+, respectively. The temperature sensitivities of Gd2(MoO4)3: Eu3+, Tb3+ based on a multimode fluorescence intensity ratio (FIR) technique were investigated for monitoring temperature changes in the range of 80–450 K. The maximum relative sensitivities of the four modes of FIR (ITb3+/IEu3+) techniques were successfully achieved with range of 0.37–0.50% K−1. The results also demonstrated the high reversibility of Gd2(MoO4)3: Eu3+, Tb3+ phosphor used as a self-calibrating thermometer for thermal-sensing application.

Intense red and green emissions from Ho3+/Yb3+ co-doped Sodium Gadolinium Molybdate Nano-phosphor: Effect of calcination temperature and Intrinsic optical bistability

We present the structural and luminescent properties of Ho3+/Yb3+ co-doped Gd0.5Na0.5MoO4 nano-phosphor synthesized through the facile co-precipitation method at different calcination temperatures. The X-ray diffraction (XRD) patterns of the samples show the pure tetragonal phase formation. The upconversion (UC) spectra recorded on excitation with 980 nm laser show the intense emission bands at 545 nm (green) and 659 nm (red) in which red emission is more intense than green emission. The intense red is suitable for bio-imaging. Under 452 nm excitation, the intense green downconversion (DC) emission is observed. It is observed that with increasing the calcination temperature, the UC/DC emission intensity increases. One of the interesting features explored is the observation of intrinsic optical bistability (IOB). This material may be applicable in various fields such as biological cell imaging, phototherapy, optical switching, display devices, solar cells, etc.

Well-defined sodium gadolinium molybdate microcrystals with diverse morphologies and dimensions: Controllable synthesis, multicolor emissions, and potential applications

Abstract A series of tetragonal phase sodium gadolinium molybdate [Na0.5Gd0.5MoO4] microcrystals with diverse particle sizes, morphologies, and dimensions have been fabricated via a mild and controllable hydrothermal approach. The synthesis process is performed under aqueous condition without using any surfactant, organic solvent, or template. The particle size and crystal shape of the hydrothermal products can be controlled by simply changing the feeding molar ratio of reactants or reaction temperature and time. Both the excellent down-conversion and up-conversion luminescence can be realized by incorporating appropriate lanthanide activator ions into the as-obtained Na0.5Gd0.5MoO4 host upon UV or NIR excitation. The calcined Na0.5Gd0.5MoO4:Ln3+ phosphors exhibit stronger emission intensity due to the enhanced crystallinity during the annealing process. Moreover, the dependence of luminescence intensity on different morphologies and performing temperatures of Na0.5Gd0.5MoO4:Ln3+ samples has been also investigated. Finally, the LED devices have been prepared by integrating the as-synthesized phosphors into UV or NIR LED chips, which exhibit dazzling characteristic multicolor emissions of Ln3+ ions under an injection current. Due to their high crystallinity, uniform and well-defined morphology, and eminent luminescence properties, the as-obtained Na0.5Gd0.5MoO4:Ln3+ phosphors may be potentially applied in fields of solid state lightening and optoelectronic devices.

Growth, Compositions, and Mechanical Characteristics of Sodium–Gadolinium Molybdate Single Crystals

A concentration series of sodium–gadolinium molybdate single crystals have been grown by the Czochralski method from melts of stoichiometric and some nonstoichiometric compositions in atmospheres with different oxygen contents. The actual compositions, microhardness, and crack resistance of the grown crystals have been investigated. All crystals are characterized by a significant sodium deficit with respect to stoichiometry and a large number of vacancies in the (Na + Gd) sublattice. The range of congruent melting is determined for this compound, and its homogeneity range is estimated to extend (on the scale of atomic concentration ratios Gd/Na) at least from 1.10 to 1.75. It is found that the microhardness of sodium– gadolinium molybdate crystals is significantly anisotropic, whereas the degree of crack resistance anisotropy does not exceed the measurement error. At the same time, neither microhardness nor crack resistance exhibit any significant dependence on the growth charge composition and the synthesis conditions in the investigated range of variation in these parameters.

Synthesis, characterization and anti-cancer applications of ytterbium doped gadolinium molybdate nanophosphor compound

Nanophosphor compounds with both diagnostic and therapeutic functions are potential for cancer diagnosis and treatment. Lanthanide complexes play a crucial role in cancer diagnosis and therapy. Gadolinium-complexes are commonly used as magnetic resonance imaging (MRI) contrast agents for cancer imaging. The role of a lanthanide, Ytterbium (Yb) in cancer treatment is not unknown. The present work focuses on finding the role of Yb when doped into Gadolinium complexes in cancer treatment. Our results demonstrate that Yb doped Gadolinium molybdate coated with biocompatible silica, effectively inhibited the viability of breast cancer cells after 24 and 48 h of treatment in in vitro, and in contrast the nanophosphor compounds did not affect the viability of healthy cells. Yb doped Gadolinium molybdate also up-regulated apoptotic genes in breast cancer cells. Hence we propose that Yb doped Gadolinium molybdate is a promising theranostic compound. To the best of our knowledge, this is the first report showing anti-cancer nature of Ytterbium-doped into Gadolinium nanophosphors.

3D Flower-Like Gadolinium Molybdate Catalyst for Efficient Detection and Degradation of Organophosphate Pesticide (Fenitrothion).

Three-dimensional (3D) nanostructured materials have received enormous attention in energy and environment remediation applications. Herein, we developed a novel 3D flower-like gadolinium molybdate (Gd2MoO6; GdM) and used as a bifunctional catalyst for the electrochemical detection and photocatalytic degradation of organophosphate pesticide fenitrothion (FNT). The flower-like GdM catalyst was prepared via a simple sol-gel technique with the assistance of urea and ethylene glycol. The properties of GdM were confirmed by various spectroscopic and analytical techniques. The GdM catalyst played a significant role in electrochemical reduction of FNT and results in a very low detection limit (5 nM), wide linear ranges (0.02-123; 173-1823 μM), and good sensitivity (1.36 μA μM-1 cm-2). Interestingly, the GdM electrocatalyst had good recoveries to FNT in soil and water sample analysis. In addition to trace level detection, the flower-like GdM was used as the photocatalyst which portrayed an excellent photocatalytic degradation behavior to eliminate the FNT in the aqueous system. The GdM photocatalyst could degrade above 99% of FNT under UV light irradiation with good stability even after five cycles.

Simulation of Simple and Complex Gadolinium Molybdates by the Interatomic Potential Method

Crystals of ferroelectric‒ferroelastic gadolinium molybdate Gd2(MoO4)3, calcium molybdate CaMoO4, and double sodium‒gadolinium molybdates of stoichiometric (Na1/2Gd1/2MoO4) and cationdeficient (Na2/7Gd4/7MoO4) compositions, which are used to design solid-state lasers, phosphors, and white LEDs, have been simulated by the interatomic potential method. Their structural, mechanical, and thermodynamic properties are calculated using a unified system of interatomic potentials and effective ion charges, which demonstrated transferability and made it possible not only to describe the existing experimental data but also to predict some important physical and thermodynamic properties of molybdate crystals. The influence of the deviation from stoichiometry and partial ordering of cations on sites in nonstoichiometric crystals on the properties and local structure of sodium‒gadolinium molybdates is discussed.

Single-step synthesis of Er3+ and Yb3+ ions doped molybdate/Gd2O3 core–shell nanoparticles for biomedical imaging

Nanostructures as color-tunable luminescent markers have become major, promising tools for bioimaging and biosensing. In this paper separated molybdate/Gd2O3 doped rare earth ions (erbium, Er3+ and ytterbium, Yb3+) core–shell nanoparticles (NPs), were fabricated by a one-step homogeneous precipitation process. Emission properties were studied by cathodo- and photoluminescence. Scanning electron and transmission electron microscopes were used to visualize and determine the size and shape of the NPs. Spherical NPs were obtained. Their core–shell structures were confirmed by x-ray diffraction and energy-dispersive x-ray spectroscopy measurements. We postulated that the molybdate rich core is formed due to high segregation coefficient of the Mo ion during the precipitation. The calcination process resulted in crystallization of δ/ξ (core/shell) NP doped Er and Yb ions, where δ—gadolinium molybdates and ξ—molybdates or gadolinium oxide. We confirmed two different upconversion mechanisms. In the presence of molybdenum ions, in the core of the NPs, Yb3+– (∣2F7/2, 3T2〉) dimers were formed. As a result of a two 980 nm photon absorption by the dimer, we observed enhanced green luminescence in the upconversion process. However, for the shell formed by the Gd2O3:Er, Yb NPs (without the Mo ions), the typical energy transfer upconversion takes place, which results in red luminescence. We demonstrated that the NPs were transported into cytosol of the HeLa and astrocytes cells by endocytosis. The core–shell NPs are sensitive sensors for the environment prevailing inside (shorter luminescence decay) and outside (longer luminescence decay) of the tested cells. The toxicity of the NPs was examined using MTT assay.

Switching of the polarization of ferroelectric–ferroelastic gadolinium molybdate in a magnetic field

A change in the character of the electric switching of polydomain ferroelectric–ferroelastic gadolinium molybdate in an external magnetic field has been detected. This change has been attributed to a magnetically stimulated increase in the pinning of domain walls. Under certain conditions, the loop of switchable polarization is degenerated into an ellipse characteristic of a linear insulator with leakage current.

Atomistic simulation of ferroelectric–ferroelastic gadolinium molybdate

Gadolinium molybdate Gd2(MoO4)3 orthorhombic ferroelectric ferroelastic (β'-phase) is simulated by the method of interatomic potentials. The simulation is performed using the GULP 4.0.1 code (General Utility Lattice Program), which is based on the minimization of the energy of the crystal structure. Parameters of the gadolinium–oxygen interatomic interaction potentials are determined by fitting to the experimental structural data and elastic constants by a procedure available in the GULP code. Atomistic modeling using the effective atomic charges and the system of interatomic potentials made it possible to obtain reasonable estimates of structural parameters, atomic coordinates, and the most important physical, mechanical, and thermodynamic properties of these crystals. Temperature dependences of the heat capacity and vibrational entropy of the crystal are obtained. The calculated parameters of gadolinium–oxygen interaction potentials can be used to simulate more complex gadolinium-containing compounds.