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With this contribution, we reply to the Comment by Tkach et al. on our publication in J. Mater. Chem. A, 2018, 6, 16101. We provide proper evidence to clarify all these queries either by providing a further explanation or through additional experimental results. From the ferroelectric characteristics and dielectric studies, we demonstrate that the remnant polarization and dielectric constant of BaTiO3 are varied with the aluminum (Al) dopant concentration and also noticed that the BaTiO3 with 2% Al dopant concentration is an optimized sample (compared to the others) to attain a high remnant polarisation and dielectric constant. Besides, the other material data of the samples are further analyzed and the presence of Al dopant content is confirmed in the BaTiO3. [ABSTRACT FROM AUTHOR]

Recently, organic–inorganic hybrid structures have gained significant interest and are considered as an innovative alternative for the development of multifunctional materials. Herein, we report highly reliable and reproducible protein–inorganic hybrid CaMoO4:Eu3+ microstructures as a novel photocatalyst for decontamination of environments using an energy-efficient and cost-effective green synthesis. In this synthesis process, streptavidin (SA) serves as an organic scaffold and builds covalent bonds with the amine groups of the CaMoO4:Eu3+ surface, which leads to the formation of membrane-bound-like structures. Because of the well overlapped absorption bands of tyrosine residues and CaMoO4:Eu3+, SA acts as a sensitizer and transfers more UV energy to the MoO4 moieties of CaMoO4:Eu3+, resulting in an enhanced emission intensity along with a blue shifted absorption spectrum. Compared to the commercial TiO2, the CaMoO4:Eu3+ host and SA modified CaMoO4:Eu3+ microstructures exhibit 145 and 207% higher dye removal efficiencies for methylene blue, signifying their light absorption efficiency and higher number of surface-active sites. After hybridization with SA, the CaMoO4:Eu3+ sample offers more photo-generated electrons to improve the photocatalytic activity along with an enhanced photocurrent density of 0.72 μA cm−2, which is about 1.5 times higher than that of the CaMoO4:Eu3+ host. Moreover, the SA modified CaMoO4:Eu3+ sample displayed excellent photocatalytic stability after 6 reusability cycles. Our synthesis strategy for protein–inorganic hybrid CaMoO4:Eu3+ opens a new avenue for the production of cutting-edge materials for industrial-scale catalysis and solid-state lighting applications. [ABSTRACT FROM AUTHOR]

Enhancing the output performance of nanogenerators using composite films consisting of a piezoelectric material embedded into polymers has gained much attention over the last few years. Such composite films can provide a high surface charge density and dielectric permittivity, which can further efficiently enhance the performance of nanogenerators. We, for the first time, employed aluminum (Al)-doped barium titanate (BaTiO3; ABTO) particles to enhance the performance of nanogenerators. These ABTO particles were synthesized via a solid-state technique, and the effect of Al dopant concentration on their crystallinity and ferroelectric properties was systematically investigated. However, the BTO particles with 2% Al dopant concentration exhibited a high remnant polarization and piezoelectric coefficient, and they were further employed to efficiently enhance the output performance of the hybrid piezo/triboelectric nanogenerators. For this, these ABTO particles were first mixed with polydimethylsiloxane (PDMS) to prepare a composite film. Next, the ABTO/PDMS composite film was employed as a piezoelectric material and triboelectric material of the hybrid nanogenerator (HNG) and exhibited a high output performance owing to their synergetic effects. In addition, the influence of the surface roughness of the composite film on the performance of the HNG was also investigated and optimized. Consequently, the HNG device with the rough surface ABTO/PDMS composite film exhibited maximal open-circuit voltage, short-circuit current, and power density values of ∼945 V, ∼59.8 μA, and ∼42.4 W m−2, respectively. For practical device application, the stable and high electrical power generated from the HNG device was employed to light several light-emitting diodes and power portable electronic devices. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) flower-like bismuth oxyiodide (BiOI) and Eu3+ or Tb3+ ions single-doped BiOI microarchitectures were successfully synthesized by a facile and eco-friendly wet chemical method in an ethylene glycol solvent. The solvent played a significant role in the formation of the 3D flower-like BiOI microarchitectures with respect to temperature and time. The phase formation of the synthesized BiOI samples was examined by X-ray diffraction analysis, which confirmed a characteristic tetragonal crystal structure with the space group of P4/nmm. The growth mechanism was discussed based on the field-emission scanning electron microscope images obtained for the samples at different growth temperatures and growth times. The crystallinity of the BiOI sample was confirmed by field-emission transmission electron microscope images. The photoluminescence (PL) properties were analyzed for the Eu3+ or Tb3+ single-doped BiOI 3D flower-like microarchitectures. The PL emission spectra of BiOI:Eu3+ samples showed intense red emission peak at 616 nm due to the 5D0→7F2 electronic transition of Eu3+ ions under 255 nm excitation. Similarly, under 253 nm (f → d transition) excitation, the PL emission spectra of BiOI:Tb3+ samples exhibited intense green emission peak at 545 nm corresponding to the f → f transitions of Tb3+ ions. Additionally, the temperature-dependent PL emission spectra were studied for the optimized BiOI:0.07Eu3+ and BiOI:0.02Tb3+ samples, indicating good thermal stability. The Commission Internationale de l'Eclairage chromaticity coordinates were calculated for the optimized samples, which showed values close to those of commercial red- and green-emitting phosphors. [ABSTRACT FROM AUTHOR]

Europium ions-activated flower-like Ba3(PO4)2 phosphor samples with assembled nanoplates were prepared by a facile synthesis route. X-ray diffraction patterns confirmed the single crystal structure with a rhombohedral phase. The synthesis mechanism of these hierarchical structures was explained from scanning electron microscope images taken at different growth times. Transmission electron microscopy was performed to further examine their crystallinity and the structural properties were also studied by Fourier transform infrared spectroscopy analysis. The optical properties were investigated by analyzing the photoluminescence (PL) excitation and emission spectra of the samples. The PL emission spectra showed red emission of trivalent europium (Eu3+) ions along with blue emission due to the reduction of Eu3+ to its divalent (i.e., Eu2+) state. The cathodoluminescence spectra of the samples were almost similar with the PL spectra without any acute changes. [ABSTRACT FROM AUTHOR]

The AgLa(PO3)4 phosphors activated with trivalent rare-earth (Eu3+, Tb3+) ions were prepared by a sol-gel synthesis method. The crystal structure of the compound was studied by X-ray diffraction patterns and found to be crystallized in the monoclinic system with a space group P21/c, indicating the calculated lattice parameters of a = 10.08 Å, b = 13.12 Å, and c = 7.314 Å. The Fourier-transform infrared spectrum, photoluminescence excitation/emission spectra, and decay curves were examined to study the optical properties. The analysis of the Eu3+ ions related emission spectrum revealed the presence of highly symmetric sites for the activator ions. The Tb3+ ions related emission spectrum exhibited a 5D3 emission due to the prolonged calcination at high temperatures, which reduces the residual hydroxyl ions. The optical properties show that this host material is suitable for phosphor materials and laser crystals. [ABSTRACT FROM AUTHOR]

The commercially available white-light-emitting diodes (WLEDs) are made with a combination of blue LEDs and yellow phosphors. These types of WLEDs lack certain properties which make them meagerly applicable for general illumination and flat panel displays. The solution for such problem is to use near-ultraviolet (NUV) chips as an excitation source because of their high excitation efficiency and good spectral distribution. Therefore, there is an active search for new phosphor materials which can be effectively excited within the NUV wavelength range (350-420 nm). In this work, novel rare-earth free self-luminescent Ca2KZn2(VO4)3 phosphors were synthesized by a citrate assisted sol-gel method at low calcination temperatures. Optical properties, internal quantum efficiency and thermal stability as well as morphology and crystal structure of Ca2KZn2(VO4)3 phosphors for their application to NUV-based WLEDs were studied. The crystal structure and phase formation were confirmed with XRD patterns and Rietveld refinement. The optical properties of these phosphor materials which can change the NUV excitation into visible yellow-green emissions were studied. The synthesized phosphors were then coated onto the surface of a NUV chip along with a blue phosphor (LiCaPO4:Eu2+) to get brighter WLEDs with a color rendering index of 94.8 and a correlated color temperature of 8549 K. [ABSTRACT FROM AUTHOR]

We synthesized the trivalent europium ions (Eu 3+ ) doped lanthanum aluminate (LaAlO 3 , LAO) nanophosphors by a solvothermal method. Their structural, morphological, and luminescent properties were systematically investigated. The obtained nanoparticles possessed single nanocrystallinity with a rhombohedral structure. For the excitation originating from the charge transfer band (O 2- to Eu 3+ ions) under 320 nm illumination, the featured emissions of Eu 3+ ions were detected in all the compounds. The optimum doping concentration of Eu 3+ ions in LAO was about 9 mol% and the concentration quenching was dominated by dipole-dipole interaction. Furthermore, the Judd-Ofelt (J-O) theory was used to estimate the J-O intensity parameters. Based on the temperature-dependent PL emission spectra, the thermal stability was analyzed and the activation energy was obtained to be 0.234 eV. Meanwhile, the decay time, color coordinate/purity, and cathodoluminescence behaviors of the synthesized nanophosphors were also studied. These characteristics make the Eu 3+ -doped LAO nanoparticles a promising red-emitting phosphor for both ultraviolet-based white light-emitting diodes and field-emission displays. [ABSTRACT FROM AUTHOR]

Eu 3+ ions activated Ca 2 La 8 (SiO 4 ) 6 O 2 (CLSO):Eu 3+ nanophosphor samples were synthesized by a mixed solvothermal and hydrothermal method. The samples were carefully studied using various characterization techniques. The XRD patterns of CLSO:Eu 3+ and CLSO confirmed that the samples were crystallized in hexagonal phase with a space group of P6 3 /m (176). The morphology of the nanoparticles was studied by varying the reaction parameters such as growth, temperature and time. The photoluminescence (PL) excitation and PL emission spectra exhibited the typical Eu 3+ bands in the wavelength range of 200-550 nm and 400-750 nm, respectively. The intensity of the [Formula: see text] electric dipole (ED) transition peak was strong in the PL emission spectrum which imparts the red color when observed under ultraviolet light. The ED transition peak intensity increased when the sample was calcined at an elevated temperature of 700 °C, indicating improved asymmetry ratio and good chromaticity coordinates. The electrical properties of the prepared materials were studied by spin-coating the powder dispersed solutions on the silica substrate. The output current values were also measured for the CLSO nanoparticles prepared under different growth conditions. These results showed the advantages of CLSO nanoparticles for their application in optics and feasibility in nanoelectronic and energy harvesting devices.

The commercially available white-light-emitting diodes (WLEDs) are made with a combination of blue LEDs and yellow phosphors. These types of WLEDs lack certain properties which make them meagerly applicable for general illumination and flat panel displays. The solution for such problem is to use near-ultraviolet (NUV) chips as an excitation source because of their high excitation efficiency and good spectral distribution. Therefore, there is an active search for new phosphor materials which can be effectively excited within the NUV wavelength range (350-420 nm). In this work, novel rare-earth free self-luminescent Ca 2 KZn 2 (VO 4 ) 3 phosphors were synthesized by a citrate assisted sol-gel method at low calcination temperatures. Optical properties, internal quantum efficiency and thermal stability as well as morphology and crystal structure of Ca 2 KZn 2 (VO 4 ) 3 phosphors for their application to NUV-based WLEDs were studied. The crystal structure and phase formation were confirmed with XRD patterns and Rietveld refinement. The optical properties of these phosphor materials which can change the NUV excitation into visible yellow-green emissions were studied. The synthesized phosphors were then coated onto the surface of a NUV chip along with a blue phosphor (LiCaPO 4 :Eu 2+ ) to get brighter WLEDs with a color rendering index of 94.8 and a correlated color temperature of 8549 K., Competing Interests: The authors declare no competing financial interests.