Laser-Induced Synthesis of CaMoO<SUB>4</SUB> Nanocolloidal Suspension and Its Optical Properties

Abstract

Pulsed laser ablation in a liquid phase was employed successfully to synthesize a calcium molybdate (CaMoO 4 ) nanocolloidal suspension. The crystalline phase, particle morphology, particle size distribution, absorbance, optical band-gap and photoluminescence (PL) were examined. Stable colloidal suspensions consisting of well-dispersed CaMoO 4 nanoparticles with a narrow size distribution could be obtained without a surfactant. The optical absorption edge located near 270 nm was blue-shifted by approximately 70 nm compared to that reported for bulk crystals. The estimated optical energy band-gap was 4.7 eV and the PL spectrum was blue-shifted at approximately 430 nm compared to the emission of bulk CaMoO 4 target (525 nm). The observed band-gap widening and blue-shift of PL emission was attributed to the quantum-size effect due to the very small size of the CaMoO 4 nanoparticles prepared by pulsed laser ablation in deionized water.

Energy transfer dynamics and luminescence properties of Eu3+ in CaMoO4 and SrMoO4

“…Such transitions are normally related to the electron-hole recombination process after excitation using the band gap of the O-Mo charge transfer transition in MoO 4 tetrahedra. 48 It is reported that in the case of CaMoO 4 emission peak maxima normally appear to be around 480-510 nm 46,47 but they are blue shifted if the size is in a nano-domain 48 due to the quantum confinement effect.…”

Self-fluorescent antibiotic MoOx–hydroxyapatite: a nano-theranostic platform for bone infection therapies

“…Please refer to the web version of this article for interpretation of the color references.Highest emission of HA was detected at  EM = 310 nm (4.00 eV) after being exited with h EX > 5 eV, figure 5a. The band gap energies increase straight with the structural order46 , so the requirement of excitation energy of about 1.5 eV inferior to the E g implies that behind this effect we should have a transition involving at least one bound state located in the gap, most probably associated with defects. In the previous section, we havedemonstrated that both HA and HA/MoO x specimens presented distortions in their lattice and in their interatomic composition.…”

Killing Bacteria by Faradaic Processes through Nano-Hydroxyapatite/MoOx Platforms

“…In particular, for nano-HA/MoO x (II), experimental data agree with reported literature values observed for the OH vacancy hydroxyapatite cell ( E g ≈ 5.5 eV), so we assume that its structure mostly accords with the latter. The nano-HA/MoO x (III) specimen, conversely, presented an E g of 4.77 ± 0.11 eV, associated with the presence of the powellite phase ( E g ≈ 4.70 eV), displaying multi-phonon and multilevel processes within the band gap interfering with the OH vacancies, V OH . The extent of V OH electronic states was computed from photoluminescence data and provided in Figures S3–S5 in the SI; a clear increase in the peak intensity can be seen for nano-HA/MoO x (II) at the characteristic emission wavelength of V OH (λ EM = 460 nm), which implies an increase in these electron acceptor states.…”