Recently, rare earth activated nanomaterials have gained much attention due to their up-conversion emission-based lighting applications. In this research, we report on the significant increase in red/green emission intensity with Er3+, Yb3+, Cr3+ tridoping than Er3+, Yb3+ codoping in the MgAl2O4 nanocrystals. Four samples with different compositions Mg0.94Er0.01Yb0.05Al2O4, Mg0.9Er0.05Yb0.05Al2O4, Mg0.89Er0.01Yb0.1Al2O4, and Mg0.93Er0.01Yb0.05Cr0.01Al2O4 were synthesized through the solution combustion method. Rietveld refinement confirmed a single-phase cubic spinel structure with the presence of lattice defects and octahedron distortion. Diffuse reflectance spectra showed broad absorption bands ascribed to host defects (such as oxygen vacancies and cation antisite defects), sharp emission peaks characteristic of Er3+ and Yb3+ ions, and broad absorption bands characteristic of Cr3+ ions. Codoped samples exhibited green and red emissions characteristic of Er3+, while 1 mol% Cr3+ incorporation led to enhanced red-green intensities and additional near-infrared emission from Cr3+ overlapping with Er3+ emission. This enhancement suggests the contribution of local lattice distortions in the tridoped sample toward strengthening the Yb3+ → Er3+ energy transfer. Consequently, the strong up-conversion photoluminescence exhibited by Er, Yb, and Cr tridoped MgAl2O4 nanocrystals highlights their potential for application in display technologies and solid-state lighting.

This study reports the synthesis of two-dimensional g-C3N4 integrated with monoclinic ZrO2 nanocomposites with different weight ratios (1: 0.5, 1:1, and 1:2, denoted as CZ1, CZ2, and CZ3) and their electrochemical performance in both three-electrode and two-electrode configurations. The structural and morphological analysis confirms the formation of a hybrid architecture, where ZrO2 nanoparticles are uniformly distributed over g-C3N4 nanosheets, promoting strong interfacial interaction. Among all compositions, CZ2 (1:1 ratio) exhibits the best electrochemical performance, delivering a high specific capacitance of 315.69 F/g and an energy density of 21.48 Wh/kg at 0.5 A/g. The enhanced performance is attributed to the optimal balance between conductivity and pseudocapacitive contribution, along with improved ion transport and increased electrochemically active surface area. Furthermore, a symmetric device based on CZ2 demonstrates a specific capacitance of 134.88 F/g and a maximum energy density of 49.13 Wh/kg at a power density of 600 W/kg. The device also shows good cycling stability, retaining 62.87% of its initial capacitance after 20,000 cycles. These results highlight the importance of composition optimization and interfacial engineering in g-C3N4/ZrO2 nanocomposites for advanced energy storage applications.

LiGa5-x(YbRCr)(x)O-8 (R = Ho, Er) ceramics were synthesized via the solid-state reaction method. Rietveld fitted X-ray diffraction (XRD) patterns conveyed an increase in the lattice parameters and tensile strain in the co-doped samples. The UV-visible absorption spectra revealed decreased band gap energy and additional near-infrared (NIR) absorption in the Yb co-doped samples. Down-conversion photoluminescence (PL) spectroscopy, with 275 nm excitation, showed strong red emission characteristics. The up-conversion PL, under 980 nm excitation, showed prominent green and red emissions for Yb-3(+)/Ho-3(+) and Yb-3(+)/Er-3(+) co-doping combinations, respectively. The mechanism of up-conversion PL was explained by energy transfer processes among Cr-3(+), Yb-3(+), Er-3(+), and Ho-3(+) ions. Colorimetric analysis showed a red emission in co-doped samples. These results highlight the potential of LiGa5O8-based phosphors for photonic and energy conversion technologies.

Er 3+ –Yb 3+ –Cr 3+ tridoped MgAl 2 O 4 nanocrystals exhibit defect-engineered lattice distortion and enhanced up-conversion emission, enabling efficient color tuning from the white to near red region under near-infrared excitation.

This study presents a comprehensive analysis of the novel composition of Ho (0.1-1 mol%) and Yb (0.5-20 mol%) co-doped MgO-Y2O3 nanocomposites for upconversion (UC) and downconversion (DC) luminescence applications. The nanocomposites were synthesized using a cost-efficient combustion method. X-ray diffraction (XRD) confirmed stable MgO and Y2O3 phases, with peak shifts and unit cell parameter variations correlating with increased dopant (Ho, Yb) concentrations. Transmission electron microscopy (TEM) revealed particle agglomeration along with clear lattice fringes, while selected area electron diffraction (SAED) confirmed well-defined ring patterns characteristic of MgO and Y2O3 crystals. Photoluminescence (PL) spectroscopy revealed strong green, red, and near-infrared (NIR) emissions under both 448 nm (downconversion; DC) and 980 nm (upconversion; DC) excitations. Power-dependent PL studies indicated three-photon absorption for green and two-photon absorption for red/NIR emissions. Notably, the intensity of the green emission saturates rapidly at 5 mol% Yb3+, while red emission saturation occurs at 15 mol%, indicating efficient energy transfer between Ho3+ and Yb3+ ions. Power-dependent PL studies unveiled a three-photon absorption mechanism for green emissions and two-photon absorption for red and NIR emissions. Temperature-dependent UC was examined over a range of 298 K to 683 K, demonstrating promising optical temperature sensing capabilities, with maximum sensitivity recorded at 51.3 x 10(-4) K-1 at 298 K. Moreover, the nanocomposites exhibited excellent stability under prolonged laser exposure, underscoring their potential for practical applications. Power-dependent tunable colorimetric parameters further highlighted their suitability for warm and cool LED technologies. Finally, the successful demonstration of these nanophosphors as security inks for anticounterfeiting applications opens new possibilities for advanced security solutions.

The present study aims to evaluate the influence of different separators on the electrochemical performance of a 2D g-C3N4 decorated Co3O4 symmetric supercapacitor. Exfoliated graphitic carbon nitride (ECN) was combined with Co3O4 to create nanocomposites in weight ratios of 1:0.01, 1:0.05, and 1:0.1 (COCN1, COCN2, COCN3). XRD analysis revealed that the ECN possesses a hexagonal structure, while Co3O4 exhibits a cubic spinel structure. COCN nanocomposites have been successfully synthesized, as confirmed by analyses using XRD and FTIR techniques. HR-TEM and SAED indicated that the CO3O4 adhered to the g-C3N4 matrix. The BET analysis revealed that the ECN and COCN2 show specific surface areas of 25 m2/g and 35 m2/g, respectively. The COCN2 nanocomposites attain a specific capacitance of 667.8 F/g at 1 A/g in 1.0 M KOH electrolyte, which is eight times more than ECN, due to the combined effects of the nitrogen content and cobalt oxidation states. The COCN2 exhibits an energy density of 45.45 Wh/kg at 218.75 W/kg power density, with 99.5 % capacitive retention. To explore the influence of different separators in symmetric devices, COCN2 was employed within the Swagelok assembly, featuring two separate types of separators: Whatman paper (COCN2/W/COCN2) and PVA-KOH gel electrolyte (COCN2/GE/COCN2). The COCN2/W/COCN2 device achieved a specific capacitance of 197.25 F/g at a current density of 1.0 A/g. Furthermore, it attained an energy density of 140.27 Wh/kg at a power density of 1600 W/kg, while retaining 94.23 % of its initial capacitance. In contrast, the COCN2/GE/COCN2 device showed a specific capacitance of 69.25 F/g and an energy density of 24.62 Wh/kg at 1600 W/kg, maintaining 95.4 % of its capacitance after 1000 cycles. The synergistic combination of Co3O4 and g-C3N4 offers a promising strategy for enhancing energy.

MgO:Ce and MgO:CeLi nanocrystals have been prepared using the solution combustion method and investigated for structural, electronic structure, photoluminescence, and thermoluminescence properties. X-ray diffraction (XRD) analysis revealed the single-phase formation of MgO:Ce amd MgO:CeLi compounds up to 0.1 mol% of Ce doping. The formation of CeO2 phase has been observed at 2 mol% Ce doping in MgO. Low energy shift in the Mg K-edge X-ray absorption near edge structure (XANES) spectra conveys favorable tetrahedral site occupancy of Mg2+ ions in MgO:Ce nanocrystals. The enhanced intensity of the O K-edge XANES feature, in MgO:Ce samples, reveals a more, p-projected, unoccupied density of states and significant hybridization of Ce 4f and O 2p states. Ce L3 edge XANES spectra confirmed the coexistence of Ce4+ and Ce3+ ions in the samples. Photoluminescence (PL) experiments, conducted with UV LED excitation at 275 nm and 310 nm, showed emissions in two regions; a blue region centered at 430 nm and a red region at 670 nm in pure MgO. Additionally, distinct emission bands corresponding to Ce 5d-4f transitions were observed and the Li co-doping could enhance the PL intensity. Thermoluminescence (TL) studies of the samples were conducted after being exposed to the different doses (100 Gy, 500 Gy, 1 kGy) of gamma radiation. The deconvolution of TL peaks has confirmed the presence of multiple traps. Kinetic parameters of TL glow peaks revealed re-trapping and closely spaced traps within the forbidden band gap. The stability and linear behavior of TL peaks demonstrated the excellent dosimetry characteristics of prepared MgO: CeLi nano phosphors.

This work evaluates the possibility of employing 2-dimensional graphitic carbon nitride (2D g-C3N4) to be utilized in supercapacitor applications as an anode material. Compared to traditional carbon-based materials, gC3N4 (CN) has various benefits, including higher energy-density and rate-capability. Therefore, we investigated the performance of a CN-based supercapacitor synthesized using an efficient and cost-effective thermal polymerization method. X-ray diffraction (XRD) data investigation indicated hexagonal symmetry composed with space group P-6 m2, indicating CN with no discernible presence of any other phases. The XRD pattern was utilised to calculate the average crystallite size, which was around 2.87 nm. In a three-electrode arrangement, electrochemical studies were performed on the CN electrode. The outcomes of this study revealed the specific capacitance (Cs) to be around 35.2 F/g at 5 mV/s when measured using cyclic voltammetry (CV) and was 39.9 F/ g at 1.0 A/g when calculated by galvanostatic charge-discharge (GCD). Finally, the construction of 2D CN based symmetric supercapacitor device was manifested and its electrochemical performance was investigated. Electrochemical studies of the symmetric supercapacitor device demonstrated a highest cell specific capacitance (Ccell) of 149.1 F/g using GCD at 0.5 A/g. The symmetric supercapacitor device exhibited an extraordinary Ecell of 141.8 Wh/kg at a Pcell of 925 W/kg. Overall, this work thoroughly analyzed the electrochemical features of 2D CN and their symmetric supercapacitor devices, and offered insightful information on its prospective use in the energy storage field, which showed that 2D CN has better electrochemical performance than other similar materials.

We demonstrate that doping a modest quantity of Cu impurity into anatase TiO2 enhances its photoinduced electrocatalytic supercapacitance by about 84% and its photocatalytic activity by more than two-fold. X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) spectroscopy analyses validate that the Cu dopant is fully incorporated into the tetragonal crystal structure of the host material and creates Ti3+ and oxygen vacancies. Furthermore, UV-vis spectroscopy and photoluminescence (PL) studies demonstrate that the smallest optical band gap energy (Eb) of 2.85 eV and minimal recombination of photoinduced charge carrier pairs occur at a 3% Cu doping amount. Transmission electron microscopy (TEM) images reveal that pristine TiO2 and Cu-doped TiO2 exhibit nearly identical pebble-like nanoparticle morphologies. This 3% Cu-doped TiO2 demonstrates more than double photodegradation (95.7%; 150 min) of a toxic Rhodamine B dye molecule and a nearly 84% improved supercapacitance (347 F g-1; 0.5 M aq. Na2SO4; pH = 7) compared to that of pristine anatase TiO2. Under suitable testing conditions of other electrolytes, molecular dyes, light intensity, etc., Cu-doped TiO2 with different particle shapes may demonstrate even greater supercapacitive behavior and photodissociation properties, leading to more advantageous applications for photoactive Cu-doped TiO2 materials.

Cr2O3/SiO2 composites with varying Cr2O3 content (10 %, 30 %, and 50 %) were synthesized and systematically analyzed for their structural, vibrational, chemical, and magnetic properties. X-ray diffraction (XRD) confirmed the successful incorporation of Cr2O3 into the SiO2 matrix, with a gradual increase in Cr2O3 phase fraction and a minor shrinkage in lattice volume, indicative of strong interparticle interactions. Raman spectra exhibited a systematic redshift and peak broadening in the characteristic Cr2O3 mode, indicative of interfacial strain and phonon confinement, while Raman mapping revealed phase clustering at higher Cr2O3 content. X-ray photoelectron spectroscopy (XPS) identified a higher Cr6+ fraction at increased Cr2O3:SiO2 fractions, indicating enhanced Cr-O-Si interactions. Magnetic measurements at 50 K and 300 K demonstrated dominant antiferromagnetic behavior alongside weak ferromagnetic contributions, attributed to defect-induced bound magnetic polarons (BMPs). BMP density increased with Cr2O3 content, highlighting localized spin interactions at the Cr2O3/SiO2 interface. These findings elucidate the interplay of structural stability, charge transfer, and defectmediated magnetism, offering insights for optimizing Cr2O3/SiO2 composites in spintronic, magneto-optical, and catalytic applications.

A remarkable 35% enhancement in the photocatalytic and electrocatalytic abilities of an ilmenite nickel titanate (NiTiO3) material is reported. This boost in catalytic performance is achieved by simply creating a static distortion in the rhombohedral unit cell by replacing a small proportion of a small-size nondegenerate Ni (69 pm) with a large-size degenerate Cu (73 pm). The materials are synthesized by using a simple sol-gel method. The appropriate doping amount of Cu facilitates the better separation of intrinsic charge carrier pairs by inhibiting their recombination. The photocatalytic and electrochemical activities of durable materials in aqueous MB dye (10 ppm) and KOH (1 molar) electrolyte solutions are found to be directly associated with this improvement in inherent charge carrier transfer characteristics. The enhanced photodissociation of MB dye (42-56%) and specific capacitance (381-450 F g(-1)) in a KOH (1 molar) electrolyte are in full accord with the investigations carried out using crystallographic and optoelectronic analysis, charging-discharging measurements, and electrochemical impedance (EIS) spectroscopy investigations. Same material with high textural surface areas or controllable particle morphologies might show a far better photo/electrocatalytic performance in a variety of practical applications.

The present study is a continuation of our previous work, where we synthesized and characterized t-ZrO2 nanocrystals through the combustion method. Further, t-ZrO2 nanocrystals are annealed at 600, 900, 1200, and 1400 degrees C and characterized through XRD, Raman, FESEM, XPS, photoluminescence (PL), and thermoluminescence (TL) techniques. XRD and Raman patterns reveal that the as-synthesized ZrO2 nanocrystals exhibit a tetragonal phase, and annealing at different temperatures induces phase transformations. Annealing at 600 degrees C restores the metastable nature of the tetragonal phase, although monoclinic nucleation is visualized through Raman spectroscopy. Annealing at higher temperatures leads to a complete transformation into the monoclinic phase. FESEM micrographs reveal extensive crystal growth and consolidation upon annealing. XPS analysis shows a reduction in the binding energies of the Zr 3d doublet due to the removal of lattice oxygen and the formation of oxygen vacancies upon annealing. The annealing of the synthesized material at 1400 degrees C induced a transformation to ferromagnetic behaviour at 300 K, with increased saturation magnetization (Ms) and coercivity (Hc), reflecting the stabilization of magnetic ordering and residual defects in the grain boundary. PL responses confirm the formation of luminescent defects in the crystal lattice. The TL response varies with the crystalline phase, annealing temperature, and radiation dose, suggesting defect creation, migration, and localization in the lattice. Overall, the study provides valuable insights into the structural and optical properties of ZrO2 nanoparticles annealed at different temperatures.

Mg1-xO:Bi-x (x = 0.01-0.5 mol%) nanophosphors have been prepared using the solution combustion method and subsequent annealing at 1173 K in air. Rietveld refinement on X-ray diffraction (XRD) data confirmed the rock-salt phase formation in pure and Bi3+ doped MgO (space group; Fm3m). Lower Bi3+ ion concentrations in Mg1-xO:Bi-x (x = 0.01 and 0.05 mol%) lead to tensile strain and increased lattice parameters of MgO. Higher doping concentrations of Bi3+ ions (x = 0.1-0.5 mol%) lead to a decrease in the lattice strain, unit cell parameters, and Mg-O bond length. Transmission electron microscopy (TEM) images along with selected area electron diffraction (SAED) patterns confirmed the crystalline nature of Mg1-xO:Bix samples with an average particle size of similar to 37.5 nm. X-ray absorption spectroscopy (XAS) results at the Mg K-edge and Bi L-edge confirmed the Mg2+ ions and Bi3+ ions in Mg1-xO:Bi-x samples throughout the Bi doping range. O-K edge XAS conveys the hybridization of the frontier orbitals of O and Bi atoms. UV-visible absorption spectroscopy measurements convey the defect-induced absorption peak shifting in Mg1-xO:Bi-x compounds. Dopant and host defect-assisted PL emission is observed, with prominent emission in the blue region owing to the transition between P-3(1) to S-1(0) and P-3(0) to S-1(0) of Bi3+. The quenching effect on PL properties has been observed beyond 0.05 mol% doping of Bi3+ ions. The presence of various defect states and their stability with re-trapping and charge transfer behaviour have been analyzed by thermoluminescence studies of gamma-irradiated samples, which enable the Mg1-xO:Bi-x samples for potential applications in display device dosimetry.

The effect of Li doping on the structural and luminescence properties of MgO were investigated in the present work. Decrease in Lattice parameter and generation of vacancies, and interstitial defects were analysed by XRD and rietveld refinement. Shift in edge energy of Mg K-edge indicates unsaturated cations which affects the PL spectra on excitation wavelength of 275 nm and 405 nm. Thermoluminescence were carried out on gamma-irradiated samples to study the defects present in the host. Li+ ions creates stable radiative favourable traps at 437 K with dose increment. The constant TL peaks with dose demonstrates the stability of the glow curves, indicates performance for dosimetry applications.

Pure, singly doped (Sm), and co -doped (Sm, Li) MgO nanoparticles have been prepared using the solution combustion method. X-ray diffraction (XRD) analysis has revealed the development of microstrain, alteration in the unit -cell parameters, and dislocation/defect densities in the MgO lattice as a function of Sm and Sm +Li doping. Transmission electron microscopy (TEM) images and selected area electron diffraction (SAED) patterns illustrate the formation of polycrystalline samples ranging from 45 nm to 65 nm in size. X-ray absorption nearedge structure (XANES) spectroscopy at Sm L -edge confirms the presence of the +3 valance state of Sm dopants. Mg K -edge XANES features convey the lesser coordination of Mg 2 + ions upon increasing the Sm 3 + ions. O K -edge XANES convey the formation of O 2- vacancies or F centers upon Sm 3 + doping. Two excitation wavelengths, lambda excitation = 275 nm, and lambda excitation = 405 nm, have shown significant emission at blue and yellow -red regions, respectively. Additionally, utilizing XANES as a methodological tool for examining defects and incorporating PL and TL findings provides a comprehensive understanding that is relatively infrequent in previous research. Thermoluminescence (TL) studies, conducted over a temperature range of 340 K to 675 K with three irradiation doses of gamma-rays (100 Gy, 500 Gy, and 1000 Gy) are convincing the formation of multiple levels of radiative traps, enhancing peak intensity at 437 K and radiation doses independent of peak intensity at 437 K.

Highly pure red phosphors LiM(PO3)(3):Eu3+ (M = Sr, Ca) doped with Eu3+ (1 mol%) were synthesized via solution combustion method and their crystal structure and luminescence dynamics were studied to explore its suitability in white light emitting diodes. The Rietveld refinement analysis of the powder X-ray diffraction patterns reveals that the phosphors belong to the pure triclinic phase of LiSr(PO3)(3) and LiCa(PO3) with space group P-1 (2). The scanning electron microscopy images showed the agglomerated morphology. The photoluminescence emission spectra under 393 nm show an orange band at 594 nm and a red band at 613 nm ascribed to D-5(0) -> F-7(1), D-5(0) -> F-7(2) transitions of Eu3+ ion in both the phosphors. Moreover, the spectroscopic properties such as luminescence behaviour, and Stark splitting were used to examine the symmetry of Eu3+ ions in LiM(PO3)(3):Eu3+ (M = Sr, Ca) phosphors in terms of distortion induced upon doping. The Stark splitting shows that the actual site symmetry for Eu3+ ion was estimated to be D-2 type for both phosphors. The photometric properties of LiCa(PO3)(3):Eu3+ such as Commission International de l'Eclairage coordinates (x = 0.64, y = 0.36) near to the standard one (red), high color purity (95%) and higher brightness reveal that the phosphor has the capability of acting as a red component in n-UV white light emitting diodes. (c) 2023 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights are reserved, including thosefor text and data mining, AI training, and similar technologies

The non-centrosymmetric phase of HfO2 with excellent Si compatibility has great importance in integrated photonic circuits, non-volatile memory, and ferroelectric field effect transistors. We report a theoretical study of pressure-induced phase transition from a centrosymmetric m-HfO2 to non-centrosymmetric o-HfO2 with Si doping. The reported phase transition pressures, i.e. 15, 14, 8, and 8 GPa for x = 0, 0.03, 0.06, and 0.09, respectively, for Hf1-xSixO2 are in excellent agreement with available experimental results. With increasing Si concentrations, the transition pressures reduce significantly, which is explained in terms of bond length and charge transfer. The thermal stability of the obtained o-HfO2 phase is examined via ab-initio molecular dynamics up to its synthesis temperature. The negative formation energy also confirms its thermodynamical stability. Density of states indicates the noticeable appearance of Si states in the lower conduction band and an increase in the extent of hybridization between Hf-5d, O-2p, and Si-2p atomic states. The doping changes the nature of band gap from indirect to direct, concurrently reducing the magnitude. The o-HfO2 shows a low value of static dielectric constant, which results in a smaller refractive index (1.82) and lower reflectivity in the infrared and visible regions.

This study delves into an examination of the structural and luminescent properties of zirconium dioxide (ZrO2) synthesized via the solid-state combustion method. Nitrates are harnessed as the oxidizing agent, while glycine serves as the fuel. Two distinct compositions are explored: a stoichiometric 1:1 ratio and a fuel-enriched 1:2 ratio. The structural analysis, employing X-ray diffraction and Raman spectroscopy, predominantly manifests a tetragonal structural phase in both samples; however, a minor monoclinic phase has also been observed in the former sample. The band gap was found to be 4.50 eV and 4.28 eV for ZrO2 synthesized in stoichiometric ratio and a fuel-enriched ratio respectively. The samples also show defects assisted photoluminescence in both the samples. The thermoluminescence of samples were investigated after irradiating the samples with UV and gamma rays for different doses. The TL curves manifest a shift towards lower temperatures at higher doses. . Significantly, the sample prepared with a 1:1 nitrate-fuel ratio exhibits a more pronounced overall TL intensity. In conclusion, our findings imply that the formation of the tetragonal phase may be influenced by strain energy, rather than being solely ascribed to size effects and oxygen vacancies within the lattice.

Herein, we report the structural, magnetic and magnetocaloric properties of Fe 50 Ni 50 alloy prepared through the planetary ball -mill. Rietveld analysis of the X-ray profiles confirmed the cubic crystallographic phase with the Fm -3 m space group. The magnetic characterization demonstrates that Fe 50 Ni 50 alloy exhibits the coexistence of magnetic interaction within the ferromagnetic phase with Curie temperature 762 K. The Arrott plot results confirmed the second -order nature of the alloy. Critical exponents were also determined using the modified Arrott plot, Kouvel-Fisher plot and critical isotherm analysis. Obtained results indicated coexisting magnetic behavior, i.e., long-range ferromagnetism and inhomogeneous magnetic state. This alloy also noted a significant magnetocaloric parameters, i.e., magnetic entropy change (- Delta S M - 2.3 J/kg-K) and relative cooling power (RCP - 230 J/kg) at 30 kOe applied field. Both parameters followed power law dependence of magnetic field, and the exponent value supports the ferromagnetic nature along with the coexisting magnetic state. By normalizing the Delta S M curve with rescaled temperature, a universal master curve is also constructed for this alloy, reiterating the second -order nature of the magnetic transition.

ZnGa2_ x(YbXCrGe)xO4 (X = Ho3+, Er3+) compounds are prepared using the solid -state -reaction method. Alteration in the lattice parameters and strain signifies the substitutional doping of elements at the octahedrally coordinated Ga3+ ions. Down -shifting PL properties are observed at the excitation wavelength of 275 nm. NIR wavelength (980 nm) induced up -conversion PL is observed in the Yb and Ho and/or Er doped samples. The prominent green -colored emission is observed in Yb3+ and Ho3+ doped sample and intense red -colored emission is achieved in the Yb3+ and Er3+ doped sample. The existence of up -conversion photoluminescence is mechanistically discussed by considering the energy transfer processes among the Zn2+, Ga3+, Yb3+, Ge3+, Cr3+, Er3+, and Ho3+ ions.