KLn(MoO4)2 micro/nanocrystals (Ln = La-Lu, Y): systematic hydrothermal crystallization, structure, and the performance of doped Eu3+ for optical thermometry

Systematic crystallization of KLn(MoO₄)₂ double molybdate micro/nanocrystals was achieved in this work for the family of lanthanide elements (excluding Pm) and Y via hydrothermal reaction under the optimized conditions of pH = 7, Mo/Ln molar ratio R = 5 and 200 °C, with which the intrinsic influence of lanthanide contraction on phase preference, crystallite morphology (size/shape) and crystal structure was clearly revealed. Extended synthesis also produced KLa_1-xEu_x(MoO₄)₂ (KLM:xEu) and KY_1-yEu_y(MoO₄)₂ (KYM:yEu) red phosphors, and detailed spectral analysis found that the layered structure of orthorhombic KYM allows Eu³⁺ to have a high quenching content of ∼70 at% (y = 0.7) and higher quantum efficiency and thermal stability of luminescence. Application also indicated that the KYM:0.7Eu optimal phosphor has the potential for optical temperature sensing with the thermally coupled ⁵D₀ and ⁵D₁ energy levels of Eu³⁺.

NaY(MoO4)2-based nanoparticles: synthesis, luminescence and photocatalytic properties

We report on a novel synthesis method, which produces NaY(MoO₄)₂ nanoparticles having an almost spherical shape and hydrophilic character. The procedure is also suitable for the preparation of NaY(MoO₄)₂-based nanophosphors by doping this host with lanthanide cations (Eu³⁺, Tb³⁺ and Dy³⁺), which, under UV illumination, exhibit intense luminescence whose color is determined by the selected doping cation (red for Eu³⁺, green for Tb³⁺ and yellow for Dy³⁺). The effects of the cations doping level on the luminescent properties are analyzed in terms of emission intensities and luminescent lifetime, to find the optimum phosphors. Finally, the performance of these nanophosphors and that of the undoped system for the photocatalytic degradation of rhodamine B, used as a model compound, is also analyzed.

Temperature-induced isostructural phase transition on NaCe(MoO4)2 system: A Raman scattering study

Temperature-dependent Raman spectroscopic study has been performed on scheelite-type sodium‑cerium molybdate - NaCe(MoO₄)₂ - in the temperature range 113-873 K. This study provides phonon properties of NaCe(MoO₄)₂, which are very important to understand the mechanism governing eventual phase transitions undergone by the structure, since phonons are very sensitive to structural changes. The ambient scheelite phase remains stable in a low-temperature range (113-293 K), and no relevant modification is observed in the Raman spectra. However, the experiments reveal the existence of one reversible phase transition at high-temperature. The vibrational spectra of NaCe(MoO₄)₂ system showed anomalies above 748 K, where overlaps of some bands and the appearance of a band at 458 cm^-1 are observed. These modifications were attributed to an isostructural phase transition and a discussion about the possible mechanism of this transformation is furnished.

Self-assembled hierarchical architecture of tetragonal AgLa(MoO4)2 crystals: hydrothermal synthesis, morphology evolution and luminescence properties

Tetragonal AgLa(MoO₄)₂ microcrystals with novel discal hierarchical architectures were successfully synthesized via a one-step hydrothermal route.

A novel anion doping strategy to enhance upconversion luminescence in NaGd(MoO4)2:Yb3+/Er3+ nanophosphors

A novel and efficient F⁻ anion doping strategy is proposed for enhancing upconversion luminescence in NaGd(MoO₄)₂:Yb³⁺/Er³⁺ nanophosphors.

Up-conversion luminescence of Er2Mo4O15 under 980 and 1550 nm excitation

The luminescence energy transfer or diffusions were limited by the long distances between Er³⁺ ions, which are based on a special structure.

Dual-mode, tunable color, enhanced upconversion luminescence and magnetism of multifunctional BaGdF5:Ln3+ (Ln = Yb/Er/Eu) nanophosphors

BaGdF₅:Yb³⁺,Er³⁺/Eu³⁺ nanophosphors were prepared by a hydrothermal method, and the energy transfer, color-tunable dual-mode emissions and magnetic properties were studied, which could have promising applications in the fields of LEDs, MRI, biolabels, and so on.

Controlled morphology and EDTA-induced pure green upconversion luminescence of Er3+/Ho3+-Yb3+ co-doped NaCe(MoO4)2 phosphor

An innovative route to increase the green UC emission and simultaneously suppress red UC emission in Er³⁺/Ho³⁺-Yb³⁺ co-doped NaCe(MoO₄)₂.

Electronic structure of β-RbSm(MoO4)2 and chemical bonding in molybdates

Microcrystals of orthorhombic rubidium samarium molybdate, β-RbSm(MoO₄)₂, have been fabricated by solid state synthesis at T = 450 °C, 70 h, and at T = 600 °C, 150 h.