Search

Alkali‐metal‐based yttrium fluoride host (AY1‒xF4:xEu3+; A: Li/Na/K) nanophosphors were developed using co‐precipitation method. Phase analysis and emission spectral behavior were established for the said nanophosphors. The highest emission observed for NaYF4 doped with Eu3+ was then optimized to achieve maximum photoluminescence (PL) emission for varied dopant amount. The downconversion and upconversion PL studies revealed pure red emission under n‐ultraviolet and infrared excitations. The CIE coordinates are observed to be lie in the red hue of the CIE diagram. The PL decay curves reported to study lifetime of the emitting state and to identify quantum efficiency using Auzel's model for the said nanophosphor. Thermal stability was also evaluated from temperature‐sensitive luminescent spectra. The studies conducted on AYF4:.05Eu3+ (A: Li/Na/K) nanophosphors contemplates that NaYF4 nanophosphors doped with Eu3+ ions are best suited for biophotonic applications as the later one show relatively high emission. [ABSTRACT FROM AUTHOR]

Let K = ℚ(ϑ) be an algebraic number field with ϑ satisfying a monic irreducible polynomial f (x) of degree n over ℚ. The polynomial f (x) is said to be monogenic if {1,ϑ,..., ϑn-1} is an integral basis of K. Deciding whether or not a monic irreducible polynomial is monogenic is an important problem in algebraic number theory. In an attempt to answer this problem for a certain family of polynomials, Jones ['A brief note on some infinite families of monogenic polynomials', Bull. Aust. Math. Soc. 100 (2019), 239-244] conjectured that if n ≥ 3, 1 ≤ m ≤ n - 1, gcd(n, mB) = 1 and A is a prime number, then the polynomial xn + A(Bx + 1)m ∈ ℤ[x] is monogenic if and only if nn + (-1)n+mBn(n - m)n-mmm A is square-free. We prove that this conjecture is true. [ABSTRACT FROM AUTHOR]

The lithium bismuth alumino borosilicate (LiBiAlBSi) glasses incorporated with different concentrations (0.1 to 2 mol%) of Er3+ ions were formed through the melt quench technique. Studies on optical absorption, photoluminescence, and decay profiles were performed. Detailed analysis of absorption and emission spectra was done by applying Judd- Ofelt (JO) theory. Under an excitation wavelength of 378 nm, the samples show intense green and NIR emission corresponding to transitions 4S3/2 → 4I15/2 (547 nm) and 4I13/2 → 4I15/2 (1538 nm), respectively. Dexter theory was applied to the NIR emission spectra to confirm the dipole–dipole nature of interaction among the Er3+ ions. CIE coordinates for the visible spectra lie in the green region. Various parameters such as stimulated emission cross-section, optical gain, and gain bandwidth for the as-prepared glasses show that these glasses exhibit good luminescence behavior and that the optimized LiBiAlBSiEr10 glass is ideal for laser applications in visible and NIR regions. [ABSTRACT FROM AUTHOR]

The luminescent materials incorporated with rare earth (RE)/transition metal (TM) ions that possess up/down conversion phenomena have found widespread applications in sensing, optical thermometry, photovoltaic/solar cells, biomedical fields and wLEDs. The augmented studies on such materials have been conducted to explore their luminescent properties for the aforementioned applications. However, how to precisely design appropriate luminescent material for certain application, how to evaluate adequacy of synthesized phosphor and finally to accomplish targeted irradiation for its desirable and practical utilization are urgently need to be clarified. In this article, a thorough overview is presented on recently explored phosphors doped with different RE/TM ions to acquire in depth knowledge about such materials and to answer the above-mentioned issues. Herein, desirable light quality for targeted application, frequently-used activators and quantitative verification methods such as cytotoxicity test and good contrast are respectively discussed for drug delivery and bio-imaging applications. The role of thermally and non-thermally coupled levels in phosphors to serve as an excellent material for thermal sensing application is reviewed. Various materials with up/down conversion are studied for improving solar cell efficiency. Different materials used for display devices and wLEDs are discussed to understand the need of developing novel materials for enhancing quantum efficiency of commercial white light emitting devices. Finally, remnant challenges in these emerging fields are addressed, our perspectives for further investigations are presented with hope that this review can pave the way for future researchers to design and study phosphors for these applications. • This review article focuses on different applications of phosphors. • The rare earth/transition metals doped phosphors have down as well as up conversion. • In drug delivery, drugs loaded phosphor materials tested for cytotoxicity. • Bioimaging applications require phosphor materials excited under NIR region. • Thermal sensing application uses FIR method to account potentiality of phosphors. • Up-conversion & downshifted phosphors are useful for solar cell applications. [ABSTRACT FROM AUTHOR]