Nano cristobalite embedded Er3+ doped multi-functional silica phosphate composite glasses for optoelectronic applications

Abstract

Composite silica-based glasses were synthesized with varying concentrations of Er3+ by sol-gel route. The presence of alkali sodium ions reoriented the silica tetrahedra, eventually forming the cristobalite phase in the glasses. The addition of Er3+ reduces the crystallite size from 23.8 nm to 6.9 nm, while retaining the fractional ceramic attribute for effectuating mechanical stability and ductility. Band gap energy increases with Er3+ doping by the principles of the Burstein-Moss shift, increasing transmittance to 90% in the glasses. The density of the glasses increases with erbium content, with a subsequent increase in ionic bonding as validated by the metallization criterion. Judd OFelt (JO) parameters were evaluated from the oscillator strengths of absorption transitions, identifying decreasing covalency in the glass systems. Broad bandwidth and lifetime of 79.9 nm and 6.2 ms respectively were obtained for near-infrared (NIR) transmission at 1.47 μm, suitable for an S-band telecommunication window. The material has potential red lasing performance corresponding to the transition: 4F9/2→4I15/2. Low dielectric constants and decreasing activation energy of the glass material at higher frequencies, as derived from Arrhenius plots, is suggestive of a cost-effective inter-layer dielectric substrate for microwave signal propagation. This could be favorably capitalized for micro-fabrication in integrated electronic industries, employing the Low-Temperature Co-fired Ceramic (LTCC) technology as a strategic alternative to the ceramic substrates devised otherwise using high sintering temperatures.