Rajah Serfoji Government College is a government college in Thanjavur, Tamilnadu, India. This college is affiliated to Bharathidasan University, Thiruchiraplli. It is located in the heart of the Thanjavur city.
Zn2V2O7:Sm (1-9 mol %) Nanoparticles (NPs), denoted as ZV:Sm, are synthesized for the first time using a solution combustion method mediated by Menthaspicata leaves extract. The doping of Sm3+ induces a shift in the hkl planes, indicating alignment with the monoclinic crystal structure and the C2/c(2/m) space group characteristic of the ZV host matrix. Additionally, a transition in surface morphology is noted, transitioning from irregularly shaped nanoparticles to hexagonal ones as the dopant concentration varies. The crystallite size, determined via Scherrer's method, concurs closely with transmission electron microscopy analysis. Moreover, analysis of the UV-Visible absorption spectra using Tauc's plot illustrates a modulation of the optical band gap, shifting from 3.03 to 2.94 eV with increasing dopant concentration. Upon excitation at 300 nm, Sm3+-doped ZV NPs exhibit characteristic spectra which arises due to 4G5/2-6H5/2 and 4G5/2-6H7/2 transition. Through experimentation, the optimal doping content is determined to be 3 mol%, which arises due to dipole dipole transition between the dopant ions and host matrix. CIE coordinates fall well within the orange-red region with increasing dopant concentration, while the average color-coordinated temperature of 3131 K suggests a warmer appearance which finds applications in photography, decorative lighting, public spaces, stage lighting, museums, galleries, etc. Electrochemical studies and Galvanostatic Charge-Discharge (GCD) analysis showed super capacitance values between 93.73 to 150.59 F/g at a scan rate of 10 mV/s, with an increasing dopant concentration, underscoring the material's potential for use in energy storage and display technologies.
Terbium-doped zinc gallate (ZnGa2O4) nanoparticles (NPs) with a cubic spinel structure were successfully synthesized via the solution combustion method employing Aloe vera gel extract as an environmentally friendly fuel. The combustion-derived powders were subsequently calcined at 600 degrees C for 3 h to enhance crystallinity. Powder X-ray diffraction (PXRD) confirmed the formation of a single-phase cubic spinel, with systematic peak shifts toward lower diffraction angles upon Tb3+ incorporation, indicating lattice strain and local distortion due to ionic size mismatch. Transmission electron microscopy (TEM) analysis shows agglomerated clusters composed of nearly spherical NPs with an average size of 13.47 nm. The optical energy band gap, estimated from diffuse reflectance spectra, decreased from 3.02 eV (undoped) to 2.94 eV (highest Tb3+ concentration), evidencing band-structure modification. Photoluminescence excitation at 310 nm yielded emission peaks at 437, 513, and 647 nm, corresponding to the 5D4-7F4, 5D4-7F5 and 5D4-7F3 transitions of Tb3+, respectively. The calculated CIE chromaticity coordinates lie within the white-light region, and the average correlated color temperature (CCT) of 8145 K suggests suitability for warm ambient illumination in residential, commercial, and decorative lighting. Electrochemical analyses in a three-electrode configuration revealed enhanced redox activity, improved electrode kinetics, and superior ionic transport with increasing Tb3+ content, achieving specific capacitances between 106.03 and 177.09 F/g at low scan rates. These results demonstrate that ZnGa2O4:Tb3+ nanoparticles possess synergistic optical and electrochemical functionalities, positioning them as promising candidates for integrated applications in solid-state lighting, display devices, and high-performance energy storage systems.
This study investigates the nonlinear optical (NLO) properties of YCrO4 (YC), YCrO4:Zn (9 mol%) (YCZ), YCrO4:Ni (9 mol%) (YCN), YCrO4:Eu (9 mol%) (YCE), and YCrO4:Tb (9 mol%) (YCT) NPs. These NPs are synthesized by Aloe vera gel extract mediated solution combustion method. The X-ray diffraction patterns of YCrO4 confirm the formation of tetragonal phase with the space group I 141/amd. No other impurity related peaks were observed even after doping with transition/rare earth metal ions except the variation in intensity. Lattice distortion in the host lattice due to the addition of dopants leads to slight shifting of Bragg peaks towards lower angle side. The direct optical band gap of YC, YCZ, YCN, YCE and YCT were tuned to 3.08, 3.05, 2.96, 2.86 and 2.75 eV respectively. The nonlinear absorption coefficient and optical limiting behavior were analyzed using the Z-scan technique under high-intensity laser irradiation. The results reveal significant variations in the nonlinear absorption coefficient among the samples, indicating the influence of dopants on the material's NLO performance. Among them, YCN exhibited the highest nonlinear absorption coefficient (14 m/W), demonstrating its strong reverse saturable absorption (RSA) characteristics. The optical limiting thresholds were also evaluated, showing that YCN had the lowest threshold (2.02 W/m2), making it a promising candidate for laser protection applications. These findings suggest that doping YCrO4 with specific elements such as Ni2+ enhances its nonlinear optical response, making it suitable for advanced photonic and optoelectronic applications.
In the present communication, Bi2O3/Al2O3 nanocomposites (NCs) are synthesized by Aloe vera gel extract mediated combustion method. Bragg reflections confirms the formation of both monoclinic Bi2O3 and orthorhombic Al2O3 nanoparticles. No other impurity related peaks were observed. The surface morphology consists small irregular shaped Bi2O3 NCs and flake like structured Al2O3 NCs. The optical energy band gap was tuned to 3.02 eV. The photoluminescence emission spectra was recorded at two excitation wavelengths 220 and 250 nm. The emission spectra recorded at Tex = 220 nm consists peaks in blue and red region whereas at Tex = 250 nm peaks located in blue, green and red region. As the excitation wavelength changes from 220 nm to 250 nm, the chromaticity coordinates shift slightly from the blue-green region to a more prominent blue region. The color correlated temperature was found to be more than 5000 K. Thus, the synthesized nanophosphor might exhibit cooler appearance and finds an application in street lights, display etc. The electrochemical performance of Bi2O3/Al2O3 nanocomposites was evaluated for supercapacitor applications. Cyclic voltammetry (CV) over 0-1000 mV at scan rates of 10-50 mV/s exhibited quasi-rectangular curves, indicating a primarily capacitive charge storage mechanism. The specific capacitance ranged from 17.49 F/g at 10 mV/s to 13.66 F/g at 50 mV/s, reflecting the diffusion-controlled ion transport. Electrochemical impedance spectroscopy (EIS) revealed low charge transfer resistance (small semicircle diameter) and diffusion-dominated behavior, while GCD curves confirmed stable, reversible charge storage. These results highlight the material's potential for energy storage, balancing energy and power density, with scope for optimization.
YCrO4:Fe (1-9 mol%) nanoparticles (NPs) were synthesized using Aloe vera gel via a solution combustion method and calcined at 600 degrees C for 3 h. X-ray diffraction confirmed a tetragonal crystal structure with no impurities. Surface morphology consists irregular sized NPs along with hollows and pores. Crystallite size and optical band gap decrease with higher dopant concentration, as determined by Scherrer's method and Wood and Tauc's plot, respectively. The photoluminescence emission spectra recorded at lambda ex= 310 nm show blue emissions at 418, 456, and 482 nm, and a green emission at 525 nm. The blue emissions are attributed to tetrahedrally coordinated Fe3+ ions. PL emission of Fe3+ for tetrahedral coordination is attributed to the transition6Al(e2,t32) <- 4Tl(e3, t22) transition. The remaining vibronic side band that appeared at 525 nm can be attributed to the local modes of vibration of a FeO4 center rather than lattice modes. The CIE coordinates lie well within the light blue region with an average CCT value of 57196 K. The synthesized sample might be suitable for applications in indoor and outdoor lighting, task lighting, healthcare, security lighting, etc. Electrochemical investigations revealed that the super capacitance values of YCrO4 nanoparticles doped with Fe3+ varied significantly, ranging from 71.79 to 110.92 F/g, when measured at a scan rate of 10 mV/s. This variation in capacitance was directly influenced by the concentration of Fe3+ ions, which was adjusted between 1 and 9 mol%. The observed trend suggests that higher dopant concentrations enhance charge storage capacity, possibly due to increased active sites and improved ion diffusion pathways within the electrode material. These findings highlight the potential of Fe-doped YCrO4 nanoparticles for advanced energy storage systems, such as supercapacitors, and indicate their suitability for integration into display technologies that require efficient energy storage solutions.
