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Self‐Driving Fluidic Micro‐Processors In article number 2200017, Milad Abolhasani and co‐workers present a self‐driving lab using artificial intelligence‐guided fluidic blocks for accelerated fundamental and applied studies of emerging clean energy materials. Autonomous doping of metal halide perovskite quantum dots is demonstrated as a material testbed of this self‐driving lab.

In this paper, we report on the influence of Li doping on the structural, morphological, electrical, optical and magnetic properties of Zn0.96-xMn0.04LixO (for x = 0.02, 0.03, 0.04) nanocrystals synthesized by a simple low-temperature co-precipitation method. Rietveld refinement of the XRD patterns confirmed single phase Wurtzite type hexagonal structure of the nanoparticles and expansion in the lattice cell volume with increasing content of Li. TEM images reveal formation of hexagon shaped nano-crystals and also show a good agreement with the crystallite size estimated from the XRD analysis. The I-V characteristics show that resistivity of the samples decreases with increasing Li concentration. The UV-Vis-NIR absorption studies show a reduction in optical energy band gap than that reported for pure ZnO which decreases gradually with increasing Li concentration, showing a qualitative agreement with the I-V characteristic results. Magnetization measurements show clear evidence of weak ferromagnetic ordering at room temperature, which increases with Li content. The observed ferromagnetism seems to show close correlation with the oxygen vacancy defects induced by Li doping.

Synthesis of nanostructured powders of tetragonal Cu2ZnSnS4 (CZTS) nanocrystals was carried out based on the hot-injection process. High-quality CZTS thin films were prepared by spin coating method onto the Corning 1737 glass substrates. CZTS nanoparticles were characterized using X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM) and high resolution TEM. It is observed that a good quality CZTS film can be obtained by spin deposition at room temperature. The optical properties of the film were studied using UV-visible spectra between 300 and 1000 nm wavelength range. The direct optical band gap of the film evolved as 1.49 eV. This value is close to the ideal band gap for highest theoretical conversion efficiency of solar cell. The optical absorption coefficients of the film between 300 and 1000 nm are found to be about 2 and 7.6 × 104 cm-1, respectively. The optical dispersion parameters of the film were also determined by Wemple-DiDomenico single oscillator model.

Defect-related luminescence, with advantages such as emission color tunability, low cost and low toxicity compared to ions activated luminescence, is a captivating route to develop luminescent materials. Herein, we synthesized KY^sub 3^F^sub 10^ phosphors by hydrothermal technique with citric acid as the chelator. SEM images indicate that the phosphors are of nanoscale and excess CA addition results in particle agglomeration. The undoped nanocrystals exhibit UV-blue band emission centered at 360 nm originated from the defects under 300 nm excitation. And the most efficient luminescence with internal quantum efficiency as high as 23.73 % has been obtained from the sample whose chelator consumption in the preparation procedure is half that of rare earth. This indicates that the lanthanide-free KY^sub 3^F^sub 10^ nanocrystals are highly efficient UV-blue-emitting phosphors. And just by doping with 3 mol% Sm^sup 3+^, the emission color could be tuned to white as a combinative effect of blue band emission from defects and line emission from Sm^sup 3+^.

The Zn(1-x)TixAl2O4 (x = 0.00, 0.05, 0.15 & 0.25) nanocrystals thin films were prepared by sol-gel method. The properties of Zn(1-x)TixAl2O4 were investigated by X-ray diffraction (XRD), Atomic Force Microscope (AFM), Fourier transform infrared spectra (FTIR) and (UV-Vis). By indexing the XRD patterns, we identified three structural types which is ZnAl2O4, anatase and rutile. The addition of TiO2 increased the crystallite size from 14.65 to 25.25 nm. The direct band gap was found to be around 3.35 to 3.84 eV. The addition of TiO2 increased the crystallite size, surface roughness, and lattice parameters of the resultant films, evidently affecting their density and dielectric constant (). The thin films were characterized in the certain frequency to determine the using LCR spectrometer. The and density value of the Zn(1-x)TixAl2O4 films increase linearly from 8.56 to 13.48 and 4.60 to 4.70 g/cm3 with the increasing of x value, respectively. Based on the material analysis and microwave antenna theory, GPS patch antennas were fabricated using the Zn(1-x)TixAl2O4 material. The fabricated GPS antenna with the highest (13.48) material exhibits the smallest size of antenna which is 7.45 cm2. The performances and the operating frequencies were measured using a PNA series network analyzer. The result showed that all patch antennas operate at frequency of 1.570 GHz. The GPS patch antenna fabricated from Zn0.25Ti0.75Al2O4 showed an excellent combination of return loss (-29.6 dB), smallest size (7.85 cm2), and wide bandwidth (195 MHz). All fabricated antennas are meets the requirements of GPS applications.

One-dimensional YVO^sub 4^:Eu^sup 3+^ nanofibre and nanospindle samples were fabricated by electrospinning and an ultrasonic chemistry method. The average diameter of the YVO^sub 4^:Eu^sup 3+^ nanofibres were 30 nm, and they mainly consisted of nanoparticles arranged in 1-d patterns. The YVO^sub 4^:Eu^sup 3+^ nanospindles, with central diameters and lengths of around 50 and 150 nm, were assembled from nanorods with central diameters and lengths of around 10 and 50 nm. Their luminescent characteristics including excitation and emission spectra, and temperature-dependent fluorescence lifetimes, were studied and compared. The luminescence intensities of Eu^sup 3+^ in YVO^sub 4^:Eu^sup 3+^ nanofibres were slightly higher than those in YVO^sub 4^:Eu^sup 3+^ nanospindles. Both the dependence of fluorescence lifetimes on the temperature of Eu^sup 3+ 5^D^sub 0^ for the YVO^sub 4^:Eu^sup 3+^ nanofibres or nanospindles remained quasi-constant, or indeed constant, over the temperature range studied, respectively; however, the lifetimes of Eu^sup 3+ 5^D^sub 0^ in YVO^sub 4^:Eu^sup 3+^ nanofibres were always shorter than those in YVO^sub 4^:Eu^sup 3+^ nanospindles at the same temperature.

Issue Title: Special Issue: Electronic Materials for Harsh Environments Zn^sub 0.94^Cu^sub 0.04^Cr^sub 0.02^O nanocrystals were synthesized by co-precipitation method and the effects of annealing at 600 °C and 800 °C under two steps on the structural, optical and morphological properties were investigated systematically. X-ray diffraction pattern showed the secondary phases such as CuO and ZnCr^sub 2^O^sub 4^ were found at 600 + 800 °C annealed sample. In addition, I^sub (002)^/I^sub (100)^ ratio became almost equal to 1 at 600 + 800 °C which described the grains with lower surface energy became larger. Chemical composition of the samples was confirmed by energy dispersive X-ray spectra. The variation of absorption peaks between 473 and 556 cm^sup -1^ and the shift of absorption frequency towards the lower side by annealing revealed that Zn-O-Zn network is perturbed by the presence of Cu/Cr in its environment. Absorption intensity and blue shift of energy gap were discussed based on size, defects and secondary phase formation. The broad transmittance spectra noticed around visible region illustrated the presence of oxygen related defects and Cu/Cr interstitials. I^sub green^/I^sub blue^ ratio is increased with increase in annealing temperature. The noticed high value of this ratio at 800 °C confirmed the existence more defect related states.

Synthesis of Ni^sub 0.64^Zn^sub 0.36^Fe^sub 2^O^sub 4^ ferrite nanoparticles via mechanical alloying and subsequent heat treatment was investigated. The pure metal powder of Zn, Fe^sub 2^O3 and NiO were ball milled in three different atmospheres including argon, oxygen and air. The X-ray diffraction results showed that after a long time of 30 h milling a desired ferrite was not produced, but heating the 30 h-activated powders in as low a temperature as 400 °C for 2 h led to the formation of Ni-Zn ferrite nanocrystals with some residual Fe^sub 2^O3 phase. The particle size and lattice parameter of the Ni-Zn ferrite samples were strongly affected by the milling atmospheres. TEM results indicated that the average particle size of the milled samples in the argon atmosphere was the smallest and in the range of 5-67 nm. FT-IR spectra for the Ni-Zn ferrite samples showed two absorption bands associated with tetrahedral and octahedral sites around 600 and 400 cm^sup -1^, which depend on the milling atmosphere; their wave-number positions were different. The VSM results indicated that the magnetic properties i.g. M^sub s^ were not only affected by the milling atmosphere but also by the sintering temperature. Although increasing sintering temperature caused an increase of the M^sub s^ value in all the three atmosphere-milled samples, the milled-sintered samples in the argon atmosphere had the biggest M^sub s^ value about 96 emu/g after sintering at 1000 °C.

Issue Title: Special Issue: Second Symposium of Renewable Energy and Sustainability: Research of Solar Materials in Mexico In this study, we report a rapid and single-step synthesis of Cu^sub 2^ZnSnS^sub 4^(CZTS) nanocrystals using microwave-assisted solution method. The influence of reaction temperature and reaction time on the phase purity, crystallographic structure, morphology and optical property of CZTS particles were investigated using X-ray diffraction, Raman spectroscopy, scanning electronic microscope, transmission electron microscopy and ultraviolet-visible spectrometer. Results revealed that the single kesterite CZTS particles with no secondary phase can be obtained by preparing samples at minimal temperature of 170 °C. The sphere-like particles, each of which contains many nanocrystals, decrease effectively in size when increasing the reaction temperature from 170 to 200 °C. The CZTS nanocrystals have an optical band gap around 1.5 eV, which is optimal for photovoltaic applications. In addition, minimal reaction time of 10 min is also essential for the growth of single kesterite CZTS. Our study demonstrated that appropriate reaction temperature and reaction time are crucial for the synthesis of high-quality CZTS by microwave irradiation method.