Dynamic luminescent labels, in which a luminescent image changes with time after ultraviolet excitation is turned off, are attractive for anticounterfeiting. A sequence of Gd2O2S:Eu3+/Ti4+ phosphors is presented in which the Ti4+ doping concentration allows the persistent emission lifetime to be varied from 1.17 ± 0.02 to 5.95 ± 0.07 s. While this persistent lifetime is tuned, the photoluminescence quantum yield remains over 46% ± 3%. A broad charge‐transfer band allows these phosphors to be excited with inexpensive and relatively safe 375 nm light‐emitting diodes. By developing patterns with phosphors that have differing persistent lifetimes, dynamic changes in the luminescent image after the excitation source is removed can be observed. For patterns made from phosphor materials that have big differences in persistent lifetimes, these dynamic changes are observable by the eye. By contrast, the dynamic changes in patterns made by phosphors with comparable persistent lifetimes (0.20 s delayed lifetime difference) are difficult to observe by the naked eye but can be easily determined by analysis of a 30‐frames‐per‐second video taken with a smartphone. Thus, these bright phosphors with tunable persistent lifetime allow both overt (observable by eye) and covert (requiring smartphone video analysis) dynamic anticounterfeiting labels to be created.

A multi-ion-beam reactive sputter (MIBERS) deposition technique was devised to grow ferroelectric lead zirconate titanate (PZT) thin films of different compositions (Zr/Ti ratios of 50/50 and 56/44) from individual metal targets of Pb, Zr, and Ti. This technique offers a highly controllable deposition process allowing excellent uniformity in composition and thickness over a large area (7.5 cm diameter) on a reproducible basis. The PZT films were deposited on a variety of unheated substrates and annealed by two different techniques, rapid thermal annealing and conventional furnace annealing. Both techniques induced a perovskite phase with good morphology. The effect of the excess Pb content was observed in terms of the crystallization and morphology. It was seen that the presence of excess Pb tends to enhance perovskite phase formation but degrades the morphology. The effect of the substrates was observed in terms of crystallization and orientation. A low-energy oxygen ion beam was employed to modify the film growth. Secondary-ion bombardment seems to be a promising approach to optimize the film quality as it showed a variety of effects such as enhancing crystallization, inducing preferred orientation, and improving the film morphology. The present MIBERS-grown PZT films showed fairly high dielectric constants, about 850 for PZT (50/50) and about 1150 for PZT (56/44), and low dielectric losses. Ferroelectricity of these films was established with the values of the remnant polarization and the coercive field for PZT (50/50) of 23 μC/cm2 and 80 kV/cm and for PZT (56/44) of 20 μC/cm2 and 60 kV/cm, respectively. The low-energy oxygen ion-beam bombardment during the growth of PZT (50/50) films caused an increase in the dielectric constant to about 1000, reduction in the dissipation factor to 0.02, increase in the remnant polarization to about 26 μC/cm2, and decrease in the coercive field to about 60 kV/cm. The C-V characteristics of PZT (50/50) films in a metal-ferroelectric-metal configuration also indicated a clear dielectric polarization hysteresis.

Cerium doped strontium sulfide nanostructures were synthesized by the solid state diffusion method in the presence of sodium thiosulfate. XRD confirmed the single phase rocksalt structure of the synthesized samples and the average grain size using the Debye–Scherrer relation is calculated to be 55 nm. TEM micrographs reveal the agglomerated whisker-like morphology with a diametre of 55–60 nm and length of several nanometres, which is in close agreement with XRD results. The effect of dopant concentration on photoluminescence (PL) intensity has been studied. PL emission for SrS : Ce (0.5 mol%) is at 481 nm with a shoulder at 530 nm at an excitation wavelength of 430 nm, which is attributed to the transitions from the 5d state to the 4f (2f7/2, 2f5/2) states of Ce3+. Ultraviolet and visible (UV–VIS) spectroscopy shows band-to-band absorption at 273 nm (4.54 eV), which is blue shifted in comparison to the band gap of bulk SrS (4.2 eV), which may be due to quantum confinement. The effect of high energy ball milling on the grain size and PL intensity has also been investigated for the first time in the doped SrS system. The PL emission wavelength is blue shifted by 3 nm but the emission intensity decreases unexpectedly as the milling time increases, although there is a reduction in size which is evident from XRD peak broadening of the milled samples. This may be ascribed to surface defects generated by ball milling which act as killing centres, quenching the PL.

Nanosized bismuth doped calcium sulfide (CaS:Bi) particles have been synthesized by a wet chemical co-precipitation method. The average size of the nanoparticles was found to be about 30 nm. The particles were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), UV–vis spectroscopy and fluorescence spectroscopy. The effect of particle size on the photoluminescence (PL) of CaS:Bi has been studied. The optimum dopant concentration was found to be 0.025 mol% of bismuth for maximum PL emission intensity. A comparative study between bulk CaS:Bi prepared by a reduction method and nanosized CaS:Bi made by the wet co-precipitation method has been carried out. Increase in band gap with decrease in particle size has been explained on the basis of the quantum size effect. The PL intensity of the nanoparticles was found to increase to almost twice that of the bulk particles. The effect of different dopant concentrations on emission intensity has also been studied.

The thermoluminescence (TL) studies of CaS : Bi nanocrystalline phosphors prepared by the wet chemical co-precipitation method and exposed to γ-rays have been discussed. The average grain size of the samples was estimated as 35 nm using Scherrer's equation. The samples exhibit a complex TL glow curve with multiple peaks. Sample exposed to γ-rays showed that the TL intensity increases linearly as the radiation doses increased in the 1.012–40.48 mGy range. The trap parameters namely, activation energy (E), order of kinetics (b) and frequency factor (s) of the main peaks of the CaS : Bi(0.08 mole%) sample have been determined using Chen's method. The effect of different dopant concentrations and different heating rates has also been discussed.