- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Influence of silicon dioxide medium on the structural and electrical properties of nickel zinc ferrite
摘要： Nickel zinc ferrite [(Ni 0:65 Zn 0:35 Fe 2 O 4)x / (SiO 2)1(cid:0)x where, x = 1.0, 0.85, 0.65, 0.50, 0.35, and 0.15] is synthesized using the glyoxylate precursor method. The synthesis, characterization, and electrical study of nickel zinc ferrites/SiO 2 powder with low dielectric constant, very low conductivity, and loss tangent with low frequency dispersion, suitable for good insulators, is reported here. X-ray diffraction, TGA, and FT-IR studies are employed for identifying crystalline phases and structure. Crystallite size is calculated by the Scherrer formula and Williamson–Hall equation and found to fall in the range of 4.9–25 nm. TEM of the samples shows spherical particles of uniform size distribution and the spotty rings of SAED patterns are analyzed for identifying the crystal planes. The study confirms a simple and efficient way to synthesize single-phase nickel zinc ferrite (NZFO) spherical particles of nano size ( (cid:25) 15 nm at 1000 ? C) with lower particle agglomeration in comparison to any other methods. Electrical studies are carried out using an LCR meter. The observed value of dielectric constant falls in the range of 10–80, loss tangent in the range of 0.05–0.4, and electrical conductivity in the range of 10 (cid:0)4 to 10 (cid:0)7 mho m (cid:0)1 . These values are respectively functions of temperature, frequency, and the ferrite content in ferrite/SiO 2 samples. A proper selection of ferrite concentration in the silica medium enables one to prepare NZFO/SiO 2 material of very low loss tangent with dielectric constant in the range of 10–80.
关键词： tetraethyl orthosilicate,dielectric constant,Nickel zinc ferrite,dielectric conductivity,loss tangent,ethylene glycol
更新于2025-09-23 15:21:21
-
Luminescent-center tuning for Ba6Ca3YAlSi6O24:Ce3+, Na+ orthosilicate phosphors
摘要： Ce3+ ion-doped Ba6Ca3YAlSi6O24 phosphors with a charge-compensating Na+ ion were prepared using a solid-state reaction. Ba6Ca3YAlSi6O24 was structurally characterized using synchrotron X-ray powder diffraction. The emission wavelengths of Ce3+ in different Ba2+ and Ca2+ sites with the distortion index of polyhedrons in the host lattice were calculated. The photoluminescence excitation and emission spectra of the Ce3+-activated phosphors were site-selectively monitored; furthermore, the emission quenching as a function of Ce3+ content in the Ba6-2xCexNaxCa3YAlSi6O24 and Ba6Ca3-2xCexNaxYAlSi6O24 (x = 0.01–0.4) was clearly distinguished at relatively high concentrations of the activator. The Gaussian components of the phosphors were exploited by using the Ce3+ ion sites in the host lattice; in addition, the one and two luminescent centers for the Ba6-2xCexNaxCa3YAlSi6O24 and Ba6Ca3-2xCexNaxYAlSi6O24 phosphors, respectively, were identified. The sites of the luminescent centers for the calculated Ba6Ca3-2xCexNaxYAlSi6O24 composition was selectively tuned as the (BaCa)9-2xCexNaxYAlSi6O24 lattice structure.
关键词： orthosilicate,photoluminescence,X-ray diffraction,luminescent center
更新于2025-09-23 15:21:01
-
Water-dispersed fluorescent silicon nanodots as probes for fluorometric determination of picric acid via energy transfer
摘要： Water-dispersed fluorescent silicon nanodots (SiNDs) were synthesized by a one-pot hydrothermal method starting from tetraethyl orthosilicate (TEOS) as silicon source and trisodium citrate as reducing reagent. The method is simple and convenient. The SiNDs, with excitation/emission peaks at 347/440 nm and with fluorescence quantum yield of 18% are shown to be viable fluorescent probes for picric acid (PA). The SiNDs strongly bind PA, and their blue fluorescence is quenched. The distance between the donor and acceptor (R0 value) is calculated from fluorescence data to be 2.1 nm. A fluorometric method was worked out that has a linear response in the 8 nM to 50 μM PA concentration range and a 0.92 nM limit of detection. The method has a fast response (2 min) and is well selective over other nitroaromatic compounds and metal ions. The average recoveries from spiked lake water samples ranged between 98.4 and 100.8%.
关键词： Nitroaromatic compounds,Picric acid (PA),Fluorometric determination,Tetraethyl orthosilicate (TEOS),Hydrothermal strategy
更新于2025-09-04 15:30:14