Preparation and Characterization of Solid-State Electrolyte Material for Energy Storage Applications

Abstract

Seven Boro-phosphate samples with composition (70 - x) B2O3 – 30 Na2O3 – xP2O5 where x=0.5%, 1%, 1.5%, 2% and 3, 5, 10 mole% and 0.02 g Er2O3 in extra were prepared using melt quenching method. From the results of X-ray Diffraction (XRD), it was confirmed that the structure of the samples was amorphous. Amorphous materials have open structure, so they can facilitate in the conduction. Samples were characterized by UV-Visible near Infrared (UV-Vis-NIR) spectroscopy. The spectroscopy was performed with wavelength ranging from 400 nm to 1600 nm to obtain the absorption peaks of the samples. Five absorption peaks were observed because of the transition from the ground state 4I15/2 to the different excited states. From the results, direct and indirect energy band gaps were calculated. Direct energy band gaps were in the range 3.59 eV - 4.18 eV. Indirect band gaps were in the range 2.92 eV - 3.95 eV. Refractive index was also calculated which was in the range 2.19 - 2.42. Photoluminescence was performed between 200 nm to 800 nm to observe the emission peaks of the samples. Two broad peaks were observed centred at 540 nm to 565 nm. These peaks were due to the transition from 2H11/2 → 4S3/2 and 4S3/2 → 4I15/2 respectively. Then Raman spectroscopy was performed on the samples between 200 cm-1 to 1600 cm-1. Under an excitation wavelength of 488 nm, characteristic Raman peaks of borate and phosphate were observed. Shifts and appearance of new bands were due to the replacement of borate with phosphate contents.