Structural study of the Eu3+ environments in fluorozirconate glasses: Role of the temperature-induced and the pressure-induced phase transition processes in the development of a rare earth’s local structure model

Obtaining the spectroscopic quality factor through the luminescent thermometry in 50Li2O · 45B2O3 · 5Al2O3 glasses doped with Nd3+ and fluorides

Lithium-boron-aluminum (LBA) glasses doped with N d ³⁺ and fluorides were produced. From the absorption spectra, their Judd-Ofelt intensity parameters, Ω _2,4,6, and spectroscopic quality factors were calculated. Exploiting their near infrared temperature dependent luminescence, we investigated their potential for optical thermometry based on the luminescence intensity ratio (LIR) methodology. Three LIR schemes were proposed, and relative sensitivity values up to 3.57±0.06% K ^-1 were obtained. From the temperature dependent luminescence, we alternatively calculated their corresponding spectroscopic quality factors. The results indicated that N d ³⁺-doped LBA glasses are promising systems for optical thermometry and as gain mediums for solid-state lasers.

Burn Chamber Test of Ex Situ Thermal Impulse Sensors

Recently, we reported on a novel ex situ thermal impulse sensing technique (based on lanthanide-doped oxide precursor nanoparticles) for use in structural fire forensics and demonstrated its functionality in small-scale lab-based tests. As a next step we have now performed a large-scale lab test at the US Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) Fire Research Laboratory using a burn chamber with three sand burners. In this test we demonstrate our technique's ability to determine the average temperature experienced by surfaces during the fire. While we successfully demonstrate our techniques accuracy, we also discover several previously unknown vulnerabilities. Namely, we find that: (1) our current method of embedding sensors in paint results in our sensor particles being difficult to recover (due to a large quantity of debris), (2) the current test panels have poor survivability, (3) debris from the fire tests interferes with excitation of dopant Dy ions (limiting our sensors' functionality), and (4) dispersal in paint results in suppression of the (metastable)tetragonal-to-monoclinic phase transition of ZrO₂. To overcome these vulnerabilities we are evaluating new panel materials, paints, and lanthanide-dopants.

Experimental and theoretical study on the optical properties of LaVO4 crystals under pressure

We report optical absorption and luminescence measurements in pure and trivalent neodymium (Nd³⁺) doped LaVO₄ crystals up to 25 GPa. We also present the theoretical framework to accurately explain the observed experimental results.