Metal Ion Substitution Research Articles

In situ reconstruction of proton conductive electrolyte from self-assembled perovskite oxide-based nanocomposite for low temperature ceramic fuel cells

In the development of low temperature solid oxide fuel cells (LT-SOFCs), also called ceramic fuel cells, the lack of highly conductive and the high manufacturing cost of dense electrolyte materials severely delay their wide development. In this work, we depart from the classic substitution approach to achieve sufficient ionic conduction (0.01 S cm−2 level at temperature ≥600 °C), a superionic conductive electrolyte material was obtained from a self-assembled hybrid oxide that was derived from the perovskite oxide precursor through alkali metal ion substitution. Moreover, the hybrid oxide was further in-situ reconstructed into a nanocomposite of oxide/carbonate-hydroxide under fuel cell condition. The nanocomposite possesses dominated proton conductivity as verified by the benefited hydration effect, versatile oxygen ionic blocking cell experiment, and concentration cell investigation. Specifically, an outstanding ionic conductivity of 0.185 S cm−1 and an excellent peak power density of 1012 mW cm−2 were demonstrated at 550 °C under an typical H2/air atmosphere. This research offers a rational design strategy to achieve low temperature, high-performance semiconductor-based functional composite electrolytes for efficient and sustainable energy conversion in SOFC technology.

Effect of substituted cobalt–chromium–iron oxides’ dissolution kinetics in oxidizing formulation on decontamination process

Removing radioactive corrosion products from Cr-containing iron oxides require a multi-step and multi-cycle decontamination process. The present article brings out the effect of divalent metal ion substitution on the release rate of chromium in the oxidative pre-treatment step. The non-stoichiometric cobalt chromium ferrites were synthesized, characterized and effect of Zn2+/Ni2+ substitution on the dissolution behavior was probed. The dissolution rates decreased with increasing the degree of inclusion and showed minima at ~ 0.4–0.6 atom% which is explained on the basis of lattice structure. It is concluded that the dissolution kinetics of native nickel–chromium ferrites in reactors increases with metal ion inclusion.

Tackling toxicity and stability using eco-friendly metal-halide ion substituted perovskite nanocrystals for advanced display color conversion

In recent years organic–inorganic hybrid halide perovskites nanocrystals have made a remarkable impact in display color converting layer application. However, lead toxicity and stability issues always pose arduous challenges. In this regard, the incorporation of a suitable metal ion to reduce toxicity and enhance stability is a widely tested method. In this study, we used a simple ligand-assisted reprecipitation (LARP) technique to simultaneously introduce metal ion and halide ion substitution by synthesizing MAPb1-xZnxBr3-2xCl2x nanocrystals (NCs). Being eco-friendly with a smaller ionic radius than lead ion, zinc metal ion was chosen as a substitute. With the variation of Zn2+ concentration, the highest quantum yield of 95 % was recorded with an emission width of 21 nm. Temperature-dependent photoluminescence (PL) studies revealed the higher optical phonon-exciton interaction after Zn2+ incorporation leading to radiative transition in NCs. Variation of PL peak energy with temperature revealed the reduced thermal chromaticity of Zn2+ incorporated NCs making them suitable for display application. Further, these NCs maintained a stable cubic structure and luminescence up to 150 °C, indicating higher thermal stability. The MAPb0.9Zn0.1Br2.8Cl0.2 (x = 0.1 or 10 mol%) NCs embedded in PMMA (poly (methyl methacrylate) polymer matrix coated LED emits narrow width, green light with color coordinate (0.15, 0.79), which is closer to green coordinate (0.17, 0.79) in Rec.2020. This helps to reproduce close to 97 % color gamut of Rec.2020. This research paves the way for finding less toxic and stable green light-emitting materials instead of cadmium-based molecules.

INVESTIGATION OF ADSORPTION OF BENTONITE SAMPLES WITH IONOGENIC OLIGOMER BY PHYSICO-CHEMICAL METHODS

The adsorption process of natural and modified Co+2-, Ni+2-bentonite samples taken from Dash-Salahli field with ionogenic oligomer modifiers was carried out and studied by x-ray and infrared spectral analysis methods. Important components that ensure the stability of bentonite suspensions are polymers, ions and surfactants. The main goal of the work is to obtain an organic mineral sorbent using an ionogenic oligomer modifier to stabilize polymer-dispersed systems. The most suitable surfactants are substances with a hydrophilic and hydrophobic statistical distribution in the molecule. The prepared sorbent has both cationic and anionic properties and can adsorb various harmful organic substances. As a result of the research, certain changes were observed in the structure of the sorbents. Depending on the ionic radii of substituted metal ions in natural bentonite, weak, medium. strong intensities are observed

Doping Effects on the Multiferroic Properties of KNbO3 Nanoparticles

The magnetization, polarization, and band-gap energy in pure and ion-doped KNbO3 (KNO) bulk and nanoparticles (NPs) are investigated theoretically using a microscopic model and Green’s function theory. It is shown that KNO NPs are multiferroic. The size dependence of M and P is studied. The magnetization M increases with decreasing NP size, whereas the polarization P decreases slightly. The properties of KNO can be tuned by ion doping, for example, through the substitution of transition metal ions at the Nb site or Na ions at the K site. By ion doping, depending on the relation between the doping and host ion radii, different strains appear. They lead to changes in the exchange interaction constants, which are inversely proportional to the lattice parameters. So, we studied the macroscopic properties on a microscopic level. By doping with transition metal ions (Co, Mn, Cr) at the Nb site, M increases, whereas P decreases. Doped KNO NPs exhibit the same behavior as doped bulk KNO, but the values of the magnetization and polarization in KNO NPs are somewhat enhanced or reduced due to the size effects compared to the doped bulk KNO. In order to increase P, we substituted the K ions with Na ions. The polarization increases with increasing magnetic field, which is evidence of the multiferroic behavior of doped KNO bulk and NPs. The behavior of the band-gap energy Eg also depends on the dopants. Eg decreases with increasing Co, Mn, and Cr ion doping, whereas it increases with Zn doping. The results are compared with existing experimental data, showing good qualitative agreement.

Hollow AMn2O4-δ (A = Co, Zn, Ni) nanotube for direct photo-oxidation of methane to C1 and C2 alcohols at atmospheric pressure and room temperature

Methane (CH4) conversion is brought into research hotspot in the field of environment, and direct photo-oxidation of methane into C1 and C2 alcohols under moderate conditions remains a huge challenge. Herein, we report a series of hollow AMn2O4-δ (A = Co, Zn, Ni) spinel nanotubes (HNTs) for the direct photo-oxidation of methane (DPOM) reaction. The results of catalytic performance demonstrated that the CH4 conversion and the yields of high value-added liquid products arrange in order of ZnMn2O4-δ HNTs > CoMn2O4-δ HNTs > NiMn2O4-δ HNTs. The ZnMn2O4-δ HNTs exhibited a superior CH4 conversion of 53.9 %, a liquid product yield of 241.7 μmol g−1h−1 (CH3OH 40.1 μmol g−1h−1, CH3CH2OH 200.9 μmol g−1h−1) and a selectivity of 100 % under light irradiation at atmospheric pressure and room temperature conditions. Xray photoelectron spectroscopy (XPS) and low-temperature electron paramagnetic resonance (EPR) analysis showed that the substitution of Zn ion at the A-site of manganate spinel significantly improved surface chemisorbed oxygen (Oα) and oxygen vacancy activity, which were beneficial to the formation of •CH3. Multi-technology photocatalytic activity characterizations results showed that ZnMn2O4-δ HNTs possessed a narrower band gap and greatly favored the separation of photogenerated carriers. Moreover, the DPOM reaction mechanism involving the formation and dehydrogenation of alkyl and alkoxy intermediates was proposed over AMn2O4-δ (A = Zn, Co, Ni) HNTs, which was investigated through temperature-programmed desorption of CH4 (CH4-TPD), in situ EPR, in situ Fourier transform infrared spectroscopy (FT-IR) and density functional theoretical (DFT) calculations. It emphasized that CH3OH was formed via the combination of •CH3 and •OH. And it was more inclined to generate CH3CH2OH through the intermediates *CH2CH3/*CH3O. This study could broaden the avenue toward the application of manganese-based spinel in the direct photo-oxidation of methane into alcohols and offer a disparate perspective on the role of the substitution of metal ion at the A-site in enhancing the photocatalytic performance.

Impact of Ligand Substitution and Metal Node Exchange in the Electronic Properties of Scandium Terephthalate Frameworks.

The search for sustainable alternatives to established materials is a sensitive topic in materials science. Due to their unique structural and physical characteristics, the composition of metal-organic frameworks (MOFs) can be tuned by the exchange of metal nodes and the functionalization of organic ligands, giving rise to a large configurational space. Considering the case of scandium terephthalate MOFs and adopting an automatized computational framework based on density-functional theory, we explore the impact of metal substitution with the earth-abundant isoelectronic elements Al and Y, and ligand functionalization of varying electronegativity. We find that structural properties are strongly impacted by metal ion substitution and only moderately by ligand functionalization. In contrast, the energetic stability, the charge density distribution, and the electronic properties, including the size of the band gap, are primarily affected by the termination of the linker molecules. Functional groups such as OH and NH2 lead to particularly stable structures thanks to the formation of hydrogen bonds and affect the electronic structure of the MOFs by introducing midgap states.

Bioinspired phosphorus-free and halogen-free biomass coatings for durable flame retardant modification of regenerated cellulose fibers

Inspired by mussel adhesion and intrinsic flame retardant alginate fibers, a biomass flame retardant (PPCA) containing adhesive catechol and sodium carboxylate structure (-COO−Na+) based on biomass amino acids and protocatechualdehyde was designed to prepare flame retardant Lyocell fibers (Lyocell@PPCA@Na). Furthermore, through the substitution and chelation of metal ions by PPCA in the cellulose molecular chain, flame retardant Lyocell fibers chelating copper and iron ions (Lyocell@PPCA@Cu, Lyocell@PPCA@Fe) were prepared. Compared with the original sample, the peak heat release rate (PHRR) and total heat release (THR) for modified Lyocell fibers were significantly reduced. In addition, the modified sample exhibited a certain flame retardant durability. TG-FTIR analysis showed that the release of flammable gaseous substances was inhibited. The introduction of Schiff bases and aromatic structures in PPCA, as well as the decomposition of carboxylic metal salts were beneficial for the formation of char residue containing metal carbonates and metal oxides to play the condensed phase flame retardant effect. This work develops a new idea for the preparation of eco-friendly flame retardant Lyocell fibers without the traditional flame retardant elements such as P, Cl, and Br.

Montmorillonite-modified stabilizing SA/CMC gel spheres cross-linked by lanthanum for tetracycline hydrochloride removal

In this study, a stable gel sphere was successfully prepared by crosslinking sodium alginate(SA) with sodium carboxymethyl cellulose(CMC) through La and modified by MMT for removing tetracycline hydrochloride (TCH). The obtained materials have been comprehensively characterized using SEM, FTIR, XRD and XPS. The results of batch experiments showed that La@SA/CMC-MMT-0.5 had a high adsorption capacity of TCH, and its maximum adsorption capacity was up to 420.95 mg/g. The adsorption process followed a pseudo-second-order kinetic model and the Freundlich isotherm model. The removal of TCH was a combined process involving both chemisorption and physical adsorption. Hydrogen-bond and complexation played a primary role in removing process, while the role of static electricity was more limited. The MMT modification not only enhanced adsorption capacity of TCH but also improved the thermal stability of the material by creating a temperature barrier and promoting hydrogen-bond. La substitution of metal ions in MMT and electrostatic attraction by MMT-surface negative charges contributed to reducing La-release. In application experiments, the La@SA/CMC-MMT-0.5 showed a high adsorption capacity, strong anti-disturbance performance, and good reusability. Therefore, La@SA/CMC-MMT-0.5 holds great potential for the effective adsorption of TCH in aqueous environments.

Cation-ordered Ni-rich positive electrode material with superior chemical and structural stability enabled by atomic substitution for lithium-ion batteries

Ni-rich layered oxides are considered as the most promising cathode materials for lithium-ion batteries (LIBs) due to their high specific capacity and low cost. However, the disordered Li/Ni mixing greatly affects their structural stability and electrochemical performance, thus hindering their wide application in commercial LIBs. Aiming to inhibit the premature death of Ni-rich layered oxides originated from the disordered Li/Ni mixing, atomic substitution of transition metal ions in LiNi0.83Co0.11Mn0.06O2 with high-valence metal molybdenum ions (denoted as Mo-NCM) is proposed in this work. The structure evolution of the as-prepared Mo-NCM caused by molybdenum substitution and the stability of Mo-NCM cathodes are comprehensively studied. Integrating experimental characterization with calculation results, it is found that the partial substitution of transition metal ions with Mo6+ ions can induce cation ordering and promote Li+ diffusion dynamics. Moreover, Mo6+ cations can act as the pillar to prevent local collapse and structural distortion, thus maintaining structural stability of the material. Furthermore, the formation of strong Mo-O bond between molybdenum and oxygen element can stabilize lattice oxygen and enhance the chemical stability of Ni-rich cathode. In addition, molybdenum modification can effectively reduce the exchange energy of Li+/Ni2+ and increase oxygen vacancy formation energy, further enhancing structural stability and promoting the kinetics of Li+ diffusion, and eventually enhancing the electrochemical performance of Mo-NCM based Li-ion batteries. The capacity retention of LIBs with 1 mol% Mo-NCM cathode can reach 98.67% after 200 cycles at 1C. This study provides a new insight into enhancing the chemical and structural robustness of Ni-rich cathode electrode materials.

Observation of room temperature ferromagnetism in transition metal ions substituted p-type transparent conducting oxide Cr2O3 thin films

In this report, we have performed comparative studies of the structural, optical, electrical, and magnetic behavior of pristine chromium oxide (PCO) and nickel (NCO), manganese (MCO), and cobalt (CCO) substituted Cr2O3 thin films. All thin films were epitaxially grown using the pulsed laser deposition (PLD) technique. X-ray diffraction (XRD) pattern confirmed the single rhombohedral phase of Cr2O3. XPS analysis confirmed the successful incorporation of Ni, Mn, and Co atoms into the Cr2O3 thin films with mixed valence states. The UV–Vis spectra illustrated the optical transparency of 65–72% in the visible region for all thin films. Electrical measurement confirmed the improvement in electrical conductivity of Cr2O3 thin films with substitution of transition metal (TM) ions. The temperature-dependent magnetization depicted ferromagnetic order. On the other hand, a field-dependent study at 5 K exhibits enhanced magnetization due to the carriers-mediated bound magnetic polarons.

A comparative study on the effect of Cr3+, Fe3+ and Ni2+ substitution on the dielectric, ferroelectric and electrocaloric response of BST ceramics

A comparative study on the influence of different 3d transition metal ions (Cr3+, Fe3+ and Ni2+) on the structural, dielectric, ferroelectric and electrocaloric response of BST ceramics is reported in the present work. Conventional solid-state reaction method was adopted for preparing the samples. A pure perovskite phase with tetragonal structure was confirmed by X-ray diffraction (XRD) analysis. Tetragonality was found to be decreased with the substitution of transition metal ions except in Cr3+ substituted sample. The dielectric behavior was investigated as a function of temperature (30 °C–150 °C) at different frequencies. Dielectric constant (ε) data was fitted with Power Law above Tc and diffused phase behavior was observed in the samples. P-E loops were recorded at different applied electric fields and temperatures. Improvement in ferroelectric properties (Pr = 10.56 μC/cm2, Ec = 2.40 kV/cm and Pr/Pmax = 0.53) was observed for Cr-substituted sample. Indirect method based on Maxwell's entropy-polarization relationship was employed to evaluate the electrocaloric effect (ECE) for all the samples. The value of ΔTmax was found to be maximum for (1.113K) for Cr substituted samples. The results show that Cr substituted BST are suitable for use in capacitor, memory devices and new generation solid-state cooling devices.

Salt-Mediated Coarsening in Conversion-Reaction-Synthesized Nanoporous Metals and Nanocomposites Resolved through In Situ Synchrotron Diffraction Studies

High-energy synchrotron X-rays were used to probe the structural and microstructural evolution in Fe, Co, and Cu nanoporous metals (NPMs) and metal/salt nanocomposites (NCs) produced by recently developed conversion reaction synthesis (CRS) methods. Microstructure analysis of as-synthesized samples via whole pattern fitting showed that the NPMs exhibit domain sizes that increase as Co < Fe < Cu, with both Fe and Co having crystallite sizes below 3.0 nm. The as-synthesized metal/salt NCs had similar metal sizes, and additionally, the salt in the composite had unusually large lattice microstrain whose origin is attributed to chemical substitution of metal ions into the salt (e.g., Li1–3xFexCl for Fe3+). When thermal annealing is used to modify crystallite size, pore collapse often occurs in NPMs but NCs can be effectively tuned without this problem. While the NC coarsening occurs slowly at low temperatures, it was found that there is a drastic acceleration of the reaction rate at a specific onset temperature that results in the crystallite size increasing by an order of magnitude in about a minute. Curiously, there was no evidence in the diffraction data for salt melting at this onset temperature. However, there was a sharp reduction in the salt chemical lattice strain at the onset temperature, indicating that rapid metal coarsening is facilitated by the salt. This behavior indicates an unexpectedly coupled reaction mechanism by which the metal ions needed for grain growth are supplied by the salt in a rate-limiting fashion.

Disruption of zinc (II) binding and dimeric protein structure of the XIAP-RING domain by copper (I) ions.

Modulation of metalloprotein structure and function via metal ion substitution may constitute a molecular basis for metal ion toxicity and/or metal-mediated functional control. The X-linked Inhibitor of Apoptosis Protein (XIAP) is a metalloprotein that requires zinc for proper structure and function. In addition to its role as a modulator of apoptosis, XIAP has been implicated in copper homeostasis. Given the similar coordination preferences of copper and zinc, investigation of XIAP structure and function upon interaction with copper is relevant. The Really Interesting New Gene (RING) domain of XIAP is representative of a class of zinc finger proteins that utilize a bi-nuclear zinc-binding motif to maintain proper structure and ubiquitin ligase function. Herein, we report the characterization of copper (I) binding to the Zn2-RING domain of XIAP. Electronic absorption studies that monitor copper-thiolate interactions demonstrate that the RING domain of XIAP binds 5-6 Cu(I) ions and that copper is thermodynamically preferred relative to zinc. Repetition of the experiments in the presence of the Zn(II)-specific dye Mag-Fura2 shows that Cu(I) addition results in Zn(II) ejection from the protein, even in the presence of glutathione. Loss of dimeric structure of the RING domain, which is a requirement for its ubiquitin ligase activity, upon copper substitution at the zinc-binding sites, was readily observed via size exclusion chromatography. These results provide a molecular basis for the modulation of RING function by copper and add to the growing body of literature that describe the impact of Cu(I) on zinc metalloprotein structure and function.

Metal Ion Substitution in a Pentanuclear Scaffold Provides an Efficient Catalyst for a HCOOH/CO2 Cycle

Here, we report that metal ion substitution in a pentanuclear scaffold provides an efficient catalyst for a photocatalytic HCOOH/CO2 cycle. A pentanuclear copper complex (Cu5) served as a catalyst that drives both photochemical formic acid production and formic acid dehydrogenation under ambient conditions with high activity and selectivity.

Structural and Biochemical Analyses of the Butanol Dehydrogenase from Fusobacterium nucleatum.

Butanol dehydrogenase (BDH) plays a significant role in the biosynthesis of butanol in bacteria by catalyzing butanal conversion to butanol at the expense of the NAD(P)H cofactor. BDH is an attractive enzyme for industrial application in butanol production; however, its molecular function remains largely uncharacterized. In this study, we found that Fusobacterium nucleatum YqdH (FnYqdH) converts aldehyde into alcohol by utilizing NAD(P)H, with broad substrate specificity toward aldehydes but not alcohols. An in vitro metal ion substitution experiment showed that FnYqdH has higher enzyme activity in the presence of Co2+. Crystal structures of FnYqdH, in its apo and complexed forms (with NAD and Co2+), were determined at 1.98 and 2.72 Å resolution, respectively. The crystal structure of apo- and cofactor-binding states of FnYqdH showed an open conformation between the nucleotide binding and catalytic domain. Key residues involved in the catalytic and cofactor-binding sites of FnYqdH were identified by mutagenesis and microscale thermophoresis assays. The structural conformation and preferred optimal metal ion of FnYqdH differed from that of TmBDH (homolog protein of FnYqdH). Overall, we proposed an alternative model for putative proton relay in FnYqdH, thereby providing better insight into the molecular function of BDH.

Comparative study of Nd3+, Cr3+-doped Mg-Zn nanoferrites

The present manuscript portrays, the structural, magnetic, and electrical properties of pristine, Neodymium (Nd3+), and Chromium (Cr3+) doped Mg-Zn nanoparticles [Mg0.9 Zn0.1MxFe2-xO4 NPs, where M = 0, Nd3+, and Cr3+] synthesized by autocombustion method. Structural characterization revealed face-centred cubic crystallinity of all the compositions with space group Fd3¯m. Even though Nd and Cr are members of the rare earth and transition metal families, the differences in their ionic radii cause variations in structural properties of Mg-Mn. The dielectric properties showed that AC conductivity increases with increasing frequency for all the compositions but was maximum for Nd3+ doped sample as compared to pristine and Cr3+ doped Mg-Zn nanoparticles. Magnetic hysteresis loop displayed superparagmagnetic behavior with negligible coercivity and retentivity but the value of saturation magnetization was maximum for Nd3+ doped Mg-Mn nanoparticles, and started decreasing with introduction of Cr3+ ions in the host Mg-Mn ferrites lattice framework, depicting improved magnetic properties due to doping of rare earth ions as compared to transition metal ion substitution. Changes in crystallite size of the host Mg-Zn crystal network, by doping rare earth ions as compared to transition metal ion induces an increment in electrical conductivity, and magnetic properties.

Chromium doped NH2(CH3)2Ga(SO4)2 × 6H2O crystal – representative of a new family of magnetoelectric materials

The paper is devoted to the detailed study of electric and magnetic properties and magnetoelectric interactions in NH2(CH3)2Ga(SO4)2 × 6H2O crystals doped with chromium—DMAGaS:Cr. The temperature dependence of the specific heat revealed clear evidence of a series of phase transitions related to the electric dipoles ordering. The different types of the DMA cation ordering in the structure of DMAGaS:Cr were evidenced in the temperature evolution of the EPR spectra. In addition, a considerable magnetoelectric coupling was demonstrated within the paramagnetic and ferroelectric phase of DMAGaS:Cr crystal. In the narrow temperature range in the vicinity of the Curie point, this crystal was found to possess the largest values of the coefficient of ME interaction as well as the largest magnetodielectric effect within the family of ferroics with organic cation. The model describing the ME effect was proposed. The magnetic field through the magnetostriction effect changes the level of the local lattice deformations caused by metal ion substitution. The applied magnetic field changes Cr-Cr distances and modifies the hydrogen bonds and process of DMA group ordering, affecting spontaneous polarization.

Regioselectivity Inversion of an O‐Methyltransferase via Semi‐rational Mutagenesis Combined with Metal Ion Substitution

AbstractS‐adenosyl‐L‐methionine (SAM)‐dependent O‐methyltransferases (O‐MTs) are a class of valuable and attractive biocatalysts for alkylation of catechols. In this work, an O‐methyltransferase (GeOMT) from the plant Galanthus elwesii was identified and characterised. GeOMT methylated a series of catechols with excellent regioselectivity. Moreover, a strategy was developed that combines structure‐directed protein engineering and metal ion substitution for regioselective inversion of GeOMT. The resultant W50M/A53N/Y186K triple variant preferentially coordinated Ni2+ instead of Mg2+ and displayed almost complete inversion in regioselectivity from 1 : 99 to 94 : 6 (para/meta) for 4‐nitrocatechol, the para‐methylated product of which is a vital plant growth regulator. This represents a promising strategy for regioselectivity improvement of O‐MTs.

Adjusting the luminescence properties by the substitution of alkali metal ions in MGd9(SiO4)6O2:Dy3+: Preparation, DFT calculation and optical properties

A series of Dy3+-doped MGd9(SiO4)6O2:Dy3+ (M = Li, Na, K) phosphors that generated white emission were prepared using the high temperature solid-state technique. Simultaneously, the phase composition, crystal structure, electronic structure, as well as the luminescence properties of the as-prepared phosphors were investigated in detail. The structural refinement showed that the MGd9(SiO4)6O2 crystallized with the hexagonal apatite-type structure. The unit cell parameters increased gradually and the main peaks of the samples in XRD patterns shifted towards high angles with the substitution of alkali-metal ions (from Li+ to K+). Under the excitation of 350 nm, the as-obtained MGd9(SiO4)6O2:Dy3+ phosphors gave bright white emission with the major emission peaks centering at 454, 477 and 573 nm. And the Ry/b, CIE chromaticity coordinate and the corrected color temperature (CCT) of the phosphors were adjusted from 0.96, (0.3256, 0.3625) and 4602 K to 1.13, (0.3369, 0.3582) and 4201 K attributing to the substitution in the crystal structure. The thermoluminescence study of MGd8.90(SiO4)6O2:0.10Dy3+ (M = Li, Na, K) showed good stability and the decay lifetimes of the samples were estimated to be about 470 μs. All the results suggested that the luminescence properties could be modified by the substitution of alkali metal ions, and the MGd9(SiO4)6O2:Dy3+ (M = Li, Na, K) phosphors have potential application as white emission candidate for w-LEDs.