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This study describes the synthesis and characterization of the lead-free organic ferroelectric perovskite N-methyl-N'-diazabicyclo [2.2.2]octonium)-ammonium trichloride (MDABCO-NH4Cl3). The electrospinning technique was employed to obtain nanofibers embedded with this perovskite in a PVC polymer for hybrid fiber production. The dielectric, piezoelectric, and pyroelectric properties of these fibers were carefully examined. Based on measurements of the dielectric permittivity temperature and frequency dependence, together with the pyroelectric results, a transition from a high temperature paraelectric to a ferroelectric phase that persisted at room temperature was found to occur at 438 K. The measured pyroelectric coefficient yielded values as high as 290 μC K−1 m−2, which is in between the values reported for MDABCO-NH4I3 and the semiorganic ferroelectric triglycine sulfate (TGS). The hybrid nanofibers exhibited good morphological characteristics and demonstrated very good piezoelectric properties. Specifically, a piezoelectric coefficient of 42 pC/N was obtained when applying a periodical force of 3 N and a piezoelectric voltage coefficient of geff = 0.65 V mN−1. The performance of these fibers is on par with that of materials discussed in the existing literature for the fabrication of nano energy-harvesting generators. Importantly, the perovskite nanocrystals within the fibers are protected from degradation by the surrounding polymer, making them a promising environmentally friendly platform for flexible mechanical energy harvesting. [ABSTRACT FROM AUTHOR]

Metal-halide perovskites have garnered considerable research attention as highly efficient light emitters in recent years due to their outstanding optoelectronic properties with remarkable tunability and excellent solution processabilities. Substantial advancements have been achieved in the development of novel halide perovskites, and the exploitations of these materials in light-emitting devices. This review comprehensively outlines recent breakthroughs in metal-halide perovskites, encompassing the rational design of perovskite materials with tunable light emission properties, the controllable growth of single crystal for a deeper understanding of their structure–property relationships, as well as the fundamental insights into the photophysics and carrier dynamics in perovskite systems. Additionally, it provides an overview of recent applications of perovskite materials in high-performance light-emitting diodes (LEDs) and lasers. [ABSTRACT FROM AUTHOR]

The impact of halide perovskites on photonics, optoelectronics and energy science is indisputable. The pursuit of perovskite nanomaterials has open roads for explorations where large surface-to-volume ratios are paramount. While the solution-phase synthesis of most nanoparticles is relatively easy, the cleaning steps for obtaining populations of high-quality nanocrystals in good yields tend to present some challenges. As an extensive number of reports show, the quality of photoluminescent nanoparticles usually correlates with increased optical-emission quantum yields. Herein, we examine the products from the cleaning steps, involving centrifugation and resuspension washes, of an established procedure for preparing cesium plumbobromide nanocrystals. The photoluminescence quantum yields of the collected nanocrystals drops by about 10% to 30% after each wash. At the same time, the average exciton lifetime increases by about a factor of four, which reflects a decrease in the radiative-decay rates by about factor of five, while the non-radiative ones increase by less than a factor of two. Further analysis indicates that decreasing the particles size, along with changing their morphology, alters some of the exciton traps, or “quenching” sites, on them. This size decrease, along with changes that accompany it, shorten the exciton lifetimes while enhancing the limited spatial overlap between the holes and the electrons of the excitons and considerably increasing the radiative rates of deactivation. These findings do not suggest that good quality nanoparticles should not necessarily manifest high emission quantum yields. Rather, they point to the complexity of nanomaterials, due to their inherent heterogeneity, that warrants multimodal analysis for understanding the exciton dynamics, while correlating it to observed structural characteristics.

The formation of intermetallic secondary phases, such as Pt3Pb, has been observed experimentally at PbTiO3/Pt and Pb(Zr,Ti)O3/Pt, or PZT/Pt, interfaces. Density functional theory calculations are used here to calculate the work of adhesion of these interfacial systems with and without the secondary intermetallic phase. The charge density maps of the interfaces reveal the electronic interactions at the interface and the impact of the secondary phase. In addition, Bader charge analysis provides a quantitative assessment of electron transfer from the perovskites to the Pt. Analysis of the band diagrams indicates an increase of the potential barrier associated with electron transfer due to the formation of the Pt3Pb at PZT/Pt interfaces. [ABSTRACT FROM AUTHOR]

Perovskite oxides and their heterostructures have demonstrated considerable potential for devices that require high carrier densities. These oxides are typically grown on ceramic substrates that suffer from low thermal conductivity, which limits performance under high currents, and from the limited size of substrates, which precludes large scale integration and processing. We address both of these hurdles by integrating oxide heterostructures with high carrier density 2D electron gases (2DEGs) directly on (001) Si. 2DEGs grown on Si show significant improvement of the high current performance over those grown on oxide substrates, a consequence of the higher thermal conductivity of the substrate. Hall analysis, transmission line measurements, and the conductance technique are employed for a detailed analysis of the carrier density, contact resistance, mobility, and electron drift velocities. Current densities of 10 A/cm are observed at room temperature with 2.9 × 1014 electrons/cm2 at a drift velocity exceeding 3.5 × 105 cm/s. These results highlight the promise of oxide 2DEGs integration on Si as channels for high electron density devices. [ABSTRACT FROM AUTHOR]

The 4d transition metal perovskites Can+1RunO3n+1 have attracted interest for their strongly interacting electronic phases showing pronounced sensitivity to controllable stimuli like strain, temperature, and even electrical current. Through multi-messenger low-temperature nano-imaging, we reveal a spontaneous striped texture of coexisting insulating and metallic domains in single crystals of the bilayer ruthenate Ca3(TixRu1-x)2O7 across its first-order Mott transition at T ≈ 95 K. We image on-demand anisotropic nucleation and growth of these domains under in situ applied uniaxial strain rationalized through control of a spontaneous Jahn-Teller distortion. Our scanning nano-susceptibility imaging resolves the detailed susceptibility of coexisting phases to strain and temperature at the transition threshold. Comparing these nano-imaging results to bulk-sensitive elastoresistance measurements, we uncover an emergent "domain susceptibility" sensitive to both the volumetric phase fractions and elasticity of the self-organized domain lattice. Our combined susceptibility probes afford nano-scale insights into strain-mediated control over the insulator-metal transition in 4d transition metal oxides. [ABSTRACT FROM AUTHOR]

Double perovskite La2-xCaxCoMnO6 (x=0, 0.1, 0.2, 0.5) ceramics samples were synthesized by the standard solid-state reaction method. The crystal structures have been confirmed to be monoclinic perovskite structure with space group of P21/n at room temperature by the powder x-ray diffraction (Cu-Ka). The grains of the samples are relatively dense and distribute in random directions from the scanning electron microscope patterns. Holes are doped into La2CoMnO6 with the substitution of the Ca2+ ions in La-site, and further lead to the valences of Mn ions and Co ions transforming from Mn4+ and Co2+ to Mn3+ and Co3+, respectively. Ferromagnetic coupling of Mn4+-O2--Co2+ and antiferromagnetic coupling of Mn3+-O2--Co3+ are coexistent in La2-xCaxCoMnO6 system, which correspond to two transitions existed in field-cooling magnetization versus temperature curves. Curie temperature of La2-xCaxCoMnO6 system decreases with the increasing of Ca-substitution amount. The coexistence of different magnetic phases leads to the exchange bias effect. [ABSTRACT FROM AUTHOR]

Double perovskite La2-xCaxCoMnO6 (x=0, 0.1, 0.2, 0.5) ceramics samples were synthesized by the standard solid-state reaction method. The crystal structures have been confirmed to be monoclinic perovskite structure with space group of P21/n at room temperature by the powder x-ray diffraction (Cu-Ka). The grains of the samples are relatively dense and distribute in random directions from the scanning electron microscope patterns. Holes are doped into La2CoMnO6 with the substitution of the Ca2+ ions in La-site, and further lead to the valences of Mn ions and Co ions transforming from Mn4+ and Co2+ to Mn3+ and Co3+, respectively. Ferromagnetic coupling of Mn4+-O2--Co2+ and antiferromagnetic coupling of Mn3+-O2--Co3+ are coexistent in La2-xCaxCoMnO6 system, which correspond to two transitions existed in field-cooling magnetization versus temperature curves. Curie temperature of La2-xCaxCoMnO6 system decreases with the increasing of Ca-substitution amount. The coexistence of different magnetic phases leads to the exchange bias effect. [ABSTRACT FROM AUTHOR]

For the first-time we have synthesised perovskite CsPbBr3 quantum dot (QD) superlattices in borosilicate glass, which play a key role in controllable network structure connectivity. The structural and optical properties of the CsPbBr3 QD superlattices embedded in borosilicate glass were investigated. [ABSTRACT FROM AUTHOR]

Metal halide perovskite nanocrystals (NCs) have shown significant potential in light‐emitting applications due to the unique luminous properties, such as high color purity, tunability, and solution processability. However, the large‐scale production of perovskite NCs with high‐quality for meeting the commercial applications is still a challenge. Herein, a facile room‐temperature synthesis of ten‐gram‐scale FAPbX3 (FA+ = HC(NH2)2+, X = Br, or mixed halide system Cl/Br and Br/I) NCs by a high‐power ultrasonic‐assisted strategy and the electroluminescence for light‐emitting diodes (LEDs) is reported. The uniform high‐power radiation avoids the adverse effects caused by heating and stirring unevenness, and no inert gas is needed in the reaction process. Meanwhile, the room temperature reaction reduces the crystallization rate of the NCs, leading to the successful synthesis of ten‐gram‐scale high‐quality FAPbX3 perovskite NCs. The resulting NCs show size‐focus distribution and high photoluminescence quantum yields of 93%, and the adjustable photoluminescence spectra from 453 to 695 nm by manipulating halide compositions. Attributed to the acquired FAPbBr3 NCs, a high‐efficiency green LED with the maximum current efficiency of 61.3 cd A−1 and external quantum efficiency of 14.1% is also obtained. [ABSTRACT FROM AUTHOR]

The preparation of luminescent Cs4PbBr6 perovskite solids with current methods either needs a complex procedure, or needs a variety of ligands, and a combination of good solvents and anti‐solvents. The potential environmental risks are inevitable when they are produced in large scale. Herein, an environmentally friendly route for the mass production of luminescent Cs4PbBr6 perovskite solids using a single solvent under ambient conditions is presented. Gram‐scale Cs4PbBr6 perovskite solids are produced within tens of minutes using a small amount of DMF, specifically, 4 mL DMF solution can produce over 10 g products per batch. Because no ligands and anti‐solvents are utilized in the whole procedures, the ligand‐free Cs4PbBr6 perovskite solids are facilely harvested after the evaporation of solvent. More importantly, the solvent vapor can be recovered and reutilized, which can eliminate the environmental pollution caused by organic solvent. The experimental results revealed that the solvent, reaction time, and PbBr2/CsBr molar ratios are crucial for the formation of Cs4PbBr6 perovskite solids and their luminescent performances. Such Cs4PbBr6 perovskite solids exhibit strong green PL emission, high PL quantum yield and reversible fluorescent response towards heat and light, which enable them to be suitable for applications in optoelectronic devices. [ABSTRACT FROM AUTHOR]

In the present study, a sonochemical‐based method for one‐pot synthesis of entropy‐stabilized perovskite oxide nanoparticle catalysts with high surface area was developed. The high‐entropy perovskite oxides were synthesized as monodispersed, spherical nanoparticles with an average crystallite size of approximately 5.9 nm. Taking advantage of the acoustic cavitation phenomenon in the ultrasonication process, BaSr(ZrHfTi)O3, BaSrBi(ZrHfTiFe)O3 and Ru/BaSrBi(ZrHfTiFe)O3 nanoparticles were crystallized as single‐phase perovskite structures through ultrasonication exposure without calcination. Notably, the entropically‐driven stability of Ru/BaSrBi(ZrHfTiFe)O3 with excellent dispersion of Ru in the perovskite phase bestowed the nanoparticles of Ru/BaSrBi(ZrHfTiFe)O3 with good catalytic activity for CO oxidation. [ABSTRACT FROM AUTHOR]

Mechanochemistry offers a solventless, 'waste free' route to preparing metal oxide catalysts, however, there is limited information on the chemical steps involved. In this work, the perovskite LaMnO3 has been successfully synthesized via mechanochemistry from metal oxide powders, La2O3 and Mn2O3, at room temperature, using a planetary ball mill. Separate ex situ 'time slices' were taken during the milling procedure to provide insights into the underlying chemistry. The crystalline material was assessed using XRD, which identified 100% perovskite phase after 3 h of milling. Conversely, characterization by X-ray absorption spectroscopy (XAS) at both the Mn K-edge and La L3-edge provides a very different picture. The XAS data shows that there are significant structural alterations as early as 30 min of milling, with the La precursor dispersed over Mn2O3. Increasing milling time then allows for mechanical activation of both precursors and the formation of powdered LaMnO3, with no calcination step required. The XAS highlights that there is a significant amount of amorphous, oxygen deficient, content even when XRD has identified 100% perovskite phase. The samples were tested for the decomposition of the environmental pollutant N2O; at a milling time of 3 h, the LaMnO3 catalyst displays a much early onset production of N2 compared to a traditional sol–gel synthesized LaMnO3, resulting from increased oxygen deficiency at the surface, confirmed by XPS and STEM-EELS. This is an encouraging sign that mechanochemical routes can be harnessed to provide a sustainable route to preparing mixed metal oxide catalysts with enhanced catalytic performance. [ABSTRACT FROM AUTHOR]

Perovskite oxides AB O 3 (A = Sr, Ba, B = Ti, Zr, Hf) were prepared at around room temperature using the reaction between alkaline earth hydroxides and metal oxide hydrous gels. The products of the reaction crystallized without any calcination. High-symmetry perovskite oxides, such as cubic perovskite, were obtained at lower temperatures. The Madelung energy of each perovskite oxide was calculated from the crystal structure and the lattice parameter obtained by XRD measurement. The calculated Madelung energy change in the synthesis reaction showed a linear relationship with the synthesis temperature. A rise in the synthesis temperature increased the change of the Madelung energy. The results thus confirmed that the synthesis temperature depended on the symmetry of the perovskite oxide in this study. Drawing from these results, we concluded that the synthesis temperature could be estimated by considering the crystal structure and Madelung energy change in the synthesis reaction. [ABSTRACT FROM AUTHOR]

For successful commercialization of perovskite solar cells, straightforward solutions in terms of environmental impact and economic feasibility are still required. Flash Infrared Annealing (FIRA) is a rapid method to fabricate perovskite solar cells with efficiencies >18% on simple, planar architecture, which allows a film synthesis in only 1.2 s, faster than the previous report based in a meso architecture and all of them without the usage of antisolvent. In this work, through a comparative study with the common lab-scale method, the so-called antisolvent (AS), the main photovoltaic parameters and working mechanisms obtained from impedance spectroscopy (IS) measurements show similar device features as for FIRA. However, from the life cycle assessment (LCA) comparison study, the FIRA method has only 8% of the environmental impact and 2% of the fabrication cost of the perovskite active layer with respect to the AS for the perovskite film synthesis. These results denote that FIRA is a low-impact, cost-effective fabrication approach that can be directly adapted to perovskite planar configuration that is compatible with industrial up-scaling. [ABSTRACT FROM AUTHOR]

A series of perovskite LaFeO3 nanoparticle-decorated TiO2 nanotube arrays (LaFeO3/TiO2 NTAs) was constructed through an electrochemical method. This type of highly ordered TiO2 NTA was first prepared by anodizing Ti sheets. LaFeO3 nanoparticles with a diameter of 10–20 nm were then electrodeposited and well dispersed on the surface of the anatase TiO2 NTAs. The as-prepared LaFeO3 nanoparticle/TiO2 NTA heterostructure showed enhanced activity than individual TiO2 NTAs and LaFeO3 for the visible light degradation of methylene blue (MB) and excellent photochemical stability. The LaFeO3 nanoparticle-modified TiO2 NTAs exhibited broad visible light harvesting and facilitated electron–hole separation, which are responsible for the high photocatalytic degradation rate of MB. This finding demonstrates the importance of promoting charge separation and transfer in heterostructured photocatalysts and also highlights the promising role of inorganic perovskite materials in photocatalytic applications. [ABSTRACT FROM AUTHOR]

We report on the synthesis of perovskite Cs 2 SnI 6 films via the solution–processed approach. The cubic Cs 2 SnI 6 phase (Fm3m group) formed at the annealing temperature of 170 °C for 8 h in air has uniform morphology. The optical characteristics of the compound depended on the annealing temperature and the compound behaved like a direct band gap semiconductor. Based on these findings, we firstly investigated the potential application of Cs 2 SnI 6 to photoelectrochemical (PEC) water splitting using a 0.3 M NaCl electrolyte. The photocurrent density (PCD) and photoconversion efficiency (η) were 0.92 mA cm−2 and 0.54% at −0.8 V, respectively. This might be suitable for fabricating the hybrid PEC device. • Synthesis of perovskite Cs 2 SnI 6 film and high stable phase in air. • Controllable of Cs 2 SnI 6 phase using the annealing approach. • A first study of photoelectrochemical characteristic of Cs 2 SnI 6 /FTO film with NaCl electrolyte. [ABSTRACT FROM AUTHOR]

A low-cost, simple, reproducible, and industry-scalable three-step approach that permits full control over film growth is used to prepare CH 3 NH 3 PbI 3– x Cl x perovskite films and the advantages of the process is demonstrated with the evidence presented for each reaction step. The whole route consists in (1) the chemical solution deposition of PbS thin films on a desired substrate; (2) the transformation of the PbS films to PbI 2 by means of a gas–solid reaction with iodine vapor; and (3) the synthesis of CH 3 NH 3 PbI 3– x Cl x perovskite by exposing the obtained PbI 2 films to a CH 3 NH 3 I/CH 3 NH 3 Cl vapor mix. The materials obtained at each step, them being PbS, PbI 2 , and CH 3 NH 3 PbI 3– x Cl x , were qualitatively evaluated regarding homogeneity and adhesion, and studied by scanning electron microscopy, X-ray photoelectron spectroscopy (including a detailed analysis of the X-ray photoelectron spectra), X-ray diffraction, and ultraviolet–visible spectroscopy. These tests and techniques demonstrate the successful obtainment of the desired material at each step of the presented route and the formation of films with strong adhesion to the glass substrate. Particularly, the inexpensive and simple synthesis of PbI 2 by an industry-compatible sequence is confirmed. Perovskite obtained by this process as an end-product was crystalline and, as confirmed by fluorescence spectroscopy, presented an energy bandgap of 1.61 eV; furthermore, the perovskite film was homogeneous and uniformly coated the substrate surface showing no pinholes. Preliminary results on the application of this perovskite in a photodetector device are also included. Image 105025 • Solution/vapor/vapor three-step approach to prepare CH 3 NH 3 PbI 3– x Cl x perovskite films. • Chemical bath deposition and (2) iodine and (3) methylammonium vapor reactions. • The whole route is simple, low-cost, reproducible, and compatible with the industry. • Obtained perovskite films are compact, homogeneous, strong-adhered, and crystalline. • Preliminary perovskite-based photodetector device is fabricated and evaluated. [ABSTRACT FROM AUTHOR]

Hexamethyldisilazane tunes morphology and enhances stability of the perovskite nanocrystals by surface modification with hydrophobic CH 3 groups. A novel facile room-temperature, hexamethyldisilazane (HMDS)-mediated strategy is demonstrated for the synthesis of all-inorganic perovskite colloidal nanocrystals (NCs). As a unique reaction-triggering and morphology-directing agent, HMDS is introduced for the first time to trigger the room-temperature reaction for generating perovskite NCs with controlled morphology and optical properties. Particularly, the stability of the resulting NCs is greatly enhanced due to the surface modification by hydrophobic -CH 3 groups from HMDS. The typical CsPbBr 3 perovskite NCs films are highly stable without significant decrease in photoluminesence (PL) intensity after being exposed to 60% relative humidity for 720 h. Moreover, no noticeable change of phase and morphology occurs even after 100 days of exposure. The representative CsPbBr 3 NCs are employed in a prototype white-light-emitting diodes (WLEDs) on 365 nm commercial GaN chip. The present strategy provides a facile and versatile route not only to control the morphology and optical properties of perovskites nanomaterials at room temperature but also enhance their stability, which will bring promising potential application for optoelectronics. [ABSTRACT FROM AUTHOR]

• Facile synthesis of perovskite type SrTiO 3 nanocubes decorated reduced graphene oxide. • The nanocomposite was successfully characterized by XRD, SEM, TEM and elemental mapping. • The SrTiO 3 @RGO electrode has been fabricated for electrochemical determination of tryptophan with the detection limit of 7.15 nM and high sensitivity 9.11 µA µM−1 cm2. • The proposed sensor was successfully applied for tryptophan determination in biological samples. In this paper, perovskite-type SrTiO 3 nanocubes decorated reduced graphene oxide is synthesized by sonochemical method. The as-synthesized SrTiO 3 @RGO nanocomposite was confirmed by XRD, TEM, SEM, elemental mapping and electrochemical technique. Furthermore, surface morphological and X-ray diffraction studies revealed the formation and high loading of SrTiO 3 nanocubes on reduced graphene oxide matrix. The SrTiO 3 @RGO nanocomposite modified electrode shows an excellent electrochemical detection towards of amino acid (tryptophan). The developed sensor was showed a wide linear range from 30 nM to 917.3 µM and detection limit is 7.15 nM. Furthermore, the sensitivity was calculated to be 9.11 µA µM−1 cm2. In addition, the proposed modified sensor is exhibited good selectivity, stability, reproducibility and repeatability. The SrTiO 3 @RGO catalyst modified electrode was successfully applied to tryptophan analysis in biological samples. [ABSTRACT FROM AUTHOR]

Single-crystalline perovskite CaTiO3 tetragonal microrods with vertical V-type holes along the [010] direction have been successfully synthesized by employing layered K2Ti6O13 nanofibers as titanate sources via a conventional hydrothermal route. The as-prepared CaTiO3 tetragonal microrods with vertical V-type holes were characterized by means of X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM and selected area electron diffraction. In order to understand the formation mechanism of the CaTiO3 tetragonal microrods with vertical V-type holes, a series of KOH concentration- and time-dependent experiments were carried out. Generally, low KOH concentrations lead to slow formation of calcium titanate species and a subsequent mild crystallization to CaTiO3 perovskite. Moreover, the dehydration and condensation of the K2Ti6O13 nanofibers and Ca(OH)2 precipitates for the calcium titanate species lead to a Ca2+ ion substitution for K+ ions in the lattice of the layered K2Ti6O13 nanofibers. In consequence, some K2Ti6O13 nanofibers are embedded in the originally formed CaTiO3 tetragonal particles and the single-crystalline perovskite CaTiO3 tetragonal microrods with vertical V-type holes along the [010] direction are derived by the dissolution of the embedded K2Ti6O13 nanofibers at a moderately low KOH concentration of ca. 1.0 mol L−1. [ABSTRACT FROM AUTHOR]

Herein a newly discovered non‐polar solvent based synthesis of MAPbX3 hybrid perovskite nanoparticles (NPs) is presented, where MA=Methylammonium and X=I, Br and Cl, as well as their mixed halide counterparts. The methodology proposed is simple and uses low‐cost commercial precursors. The conventional method of hybrid perovskite preparation requires methylammonium halide precursors and highly polar solvents. Mandatory use of polar solvents and a particular perovskite precursor makes an intermediate compound which then requires a non‐polar solvent to recover the NPs. In contrast here, a whole range of mixed halide perovskite NPs is fabricated without using a methylammonium halide precursor and a polar solvent. In this method, a non‐polar solvent is used, which provides a better platform for the particle recovery. Organic cations on the nanoparticle surface prevent degradation from water, due to their hydrophobic nature, and hence offer a stable colloidal suspension in toluene for more than three months. Ab‐initio calculations within density functional theory (DFT) predict lower formation energies compared to previously reported values, confirming better chemical stability for this synthesis pathway. Through the halide compositional tuning, these NPs exhibit a variety of emission and absorption starting from ultraviolet to near infrared (IR). The absorption spectra of various halide perovskite show a sharp band edge over the visible wavelength with high absorption coefficient. High oscillator strengths due to high excitonic binding energies combined with the simulated finite dipole transition probabilities point towards the observed high absorption. The emission spectra of mixed halide perovskites vary from 400 to 750 nm, which covers the whole range of visible spectra with sharp full‐width at half maxima. Different halide perovskite exhibit average recombination lifetime from 5 to 227 ns. Ambient synthesis, chemical robustness and tunability of emission with varying halide compositions make MAPbX3 (X=I, Br and Cl) NPs appealing for the optoelectronic applications. [ABSTRACT FROM AUTHOR]

Nanocrystalline Gd 0.9 Bi 0.1 FeO 3 porous structure perovskite has been successfully synthesized by hydrothermal route. The detailed structural and morphological information were carried out through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM). The composition of the perovskite and oxidation states were established with the use of energy-dispersive X-ray spectroscopy (EDX) and X-Ray photoelectron spectroscopy (XPS), respectively. The Brunauer Emmett-Teller (BET) isotherm of the synthesized materials gave the pore size distribution and surface area of the particles. The optical property of the material was established with the use of UV–Visible spectrometer. The magnetic properties of the samples were measured using vibrating sample magnetometer (VSM) under applied magnetic field of 1.5 TT and room temperature electron paramagnetic resonance (EPR) spectra. The perovskite exhibits paramagnetic behaviour since the magnetization increases linearly with increasing magnetic field. The exchange interaction between different magnetic sub-lattices due to coupling interaction between dopant (Bi3+ ions) which is weakly ferromagnetic with the Fe sub-lattice and (anti-ferromagnetic) Gd sub-lattice thereby enhanced the magnetic property of the synthesized new material. The photoluminescence (PL) property was carried out using spectrofluorometer with the analysis range between 400 and 800 nm. The fluorescence spectral lines are observed in the visible range which attributed due to characteristic f–f transition lines of Bi3+ ions. Image 1 • Nanocrystalline Gd 0.9 Bi 0.1 FeO 3 perovskite with porous structure has been successfully prepared. • The microscopy images showed the perovskite was highly crystalline and porous nature. • Enhanced photoluminescence observed with respect to the dopant and temperature. • Ferromagnetic magnetic signal detected for GdFeO 3 perovskite by doping the Bi ion. [ABSTRACT FROM AUTHOR]

Perovskite LaFeO 3 nanoparticles with a size of less than 50 nm have been synthesized by sol-gel method using citric acid, oxalic acid, and succinic acid as chelating agents. The obtained products were characterized by various techniques like XRD, FT-IR, HRTEM, and SAED. The elemental composition was analyzed by EDX. The magnetic and ferroelectric properties were investigated using VSM and Precision multiferroic tester. Batch experiments were conducted to test the ability of LaFeO 3 samples for removal of cadmium (Cd2+) from the contaminated water. The concentration of heavy metal ion was monitored by AAS technique. Adsorption studies revealed that the LaFeO 3 prepared by succinic acid possess high adsorption capacity. Image 1075 • Perovskite LaFeO 3 nanoparticles of the size (<50 nm) have been synthesized by sol-gel method. • Magnetic, ferroelectric and leakage properties were investigated. • Perovskite LaFeO 3 shown good performance towards removal of cadmium ions. [ABSTRACT FROM AUTHOR]

Highlights • Heterojunction Ag,F co-doped Bi 2 MoO 6 /reduced graphene oxide photocatalysts were synthesized via a solvothermal-calcination method. • The insertion of Ag+ and F− into Bi 2 MoO 6 led to decrease the band gap energy from 2.78 eV to 2.6 eV. • RhB removal by the novel photocatalyst exceeded 99% within 120 min. • The novel photocatalyst remained stable up to 4 consecutive runs. Heterojunction z-scheme based Ag,F co-doped Bi 2 MoO 6 /reduced graphene oxide (Ag,F@BMO/rGO) photocatalysts were synthesized via a facile solvothermal method. The present work describes the improved photocatalytic activity of BMO/rGO nanocomposite by co-doping of F− and Ag+ ions, to remove RhB from aqueous solution. The XRD, N 2 adsorption, SEM, TEM, EDS, UV–Vis DRS, FT-IR, Raman, and PL measurements were employed to characterize the crystallographic, morphological, and optical properties. X-ray diffraction analysis suggests that crystal growth of all the as-prepared nanoparticles with different F− and Ag+ contents has occurred in Aurivillius phase and the crystal structure did not affected by doping. The insertion of Ag+ and F− into Bi 2 MoO 6 led to a red-shift in the absorption edge of nanocomposite and decrease the band gap energy from 2.78 eV to 2.6 eV, due to the synergetic effects of Surface Plasmon Resonance and surface oxygen vacancy induced by Ag+ and F−, respectively. These beneficial properties are explored toward the photodegradation of RhB under visible-light source, resulting in better yields at lesser exposure time. The photocatalytic activity was significantly influenced by rGO in the nanocomposite, which was 2 times higher than that of pure Bi 2 MoO 6 , by effective separation of the charge carriers. The separation behaviors of photogenerated electron-hole were also systematically investigated by the PL. Based on the radical trapping experiments, photogenerated holes and O 2 •− were the main active species in RhB photodegradation and the detailed decolorization pathway has been suggested, using liquid chromatography/mass spectrometry (LC/MS) technique. In addition, the Ag,F@BMO/rGO nanocomposite does not display dramatic reduction of catalytic performance after four recycles, reveals its great prospect and promising application for water purification. [ABSTRACT FROM AUTHOR]

Lead-free inorganic perovskites are promising for optoelectronic applications. Understanding their phase diagram and defect properties is beneficial to predict the stable phase and applications. Here, taking CsSnCl3 as an example, the stability and defect properties are investigated systemically. The results show that the stoichiometric CsSnCl3 can only be grown in a narrow area determined by Sn and Cs chemical potentials. No matter what the Sn condition is, both acceptor defects (Cs- and Sn-vacancies with low charge states) are formed spontaneously with negative formation energies, and the donor defects are difficult to be formed with high formation energies. Interestingly, these charge-state transition levels induced by such stable defects are in the valence band. Meanwhile, no deep acceptor and donor states are formed in the bandgap. In addition, although the Fermi levels can vary in a wide range, the Fermi levels are pinned in the valence band, irrespective of the atmospheric conditions, leading to p-type CsSnCl3 with high hole density and low electron density. Such electronic characters are elucidated in detail by the atomic orbitals and structural deformations. Our studies provide an insight view of the defect properties of CsSnCl3 and provide a valuable guideline for CsSnCl3 fabrication and further modulation. [ABSTRACT FROM AUTHOR]

All inorganic perovskite nanocrystals (AIPNCs) have attracted tremendous research interest due to their fascinating properties in the field of photoelectron. Conventional synthesis of AIPNCs is usually conducted by using batch reactions under gas protection at high temperatures. Herein, an automated microreactor platform consisting of flow-focusing microfluidics is firstly applied to synthesize AIPNCs without gas protection at room temperature. The nucleation and growth is based on the ultrafast mixing and phase separation in low-toxicity solvent. The AIPNCs formed in the microreactor have good crystallinity and narrow size distribution. Meanwhile, the flow-focusing microfluidics also can be used to encapsulate AIPNCs into templated microspheres to improve their stability against temperature, light and water. Furthermore, the as-constructed AIPNC spheres exhibiting linear temperature response represent their promising microthermometer application. It is envisioned that the microfluidic technique provides another alternative to synthesize Ni2+-doped, Ce3+-doped, Yb3+-doped, Bi3+-substituted AIPNCs or organic-inorganic hybrid perovskite nanocrystals and to fabricate templated AIPNC materials and devices. [ABSTRACT FROM AUTHOR]

The dense structure required by mixed-ionic and electronic conducting (MIEC) membrane based on La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) material could be influenced by the particle size of the LSCF, as this densification involves sintering of the particles. The particle size could be determined by using an appropriate synthesis method. The aim of this work is to investigate the effect of synthesis method to the particle size of the resulted powders. In this work, LSCF was successfully synthesized by sol-gel, co-precipitation, and solid-state methods. The coprecipitation is carried out with and without aging treatment after addition of precipitating agent. All LSCFs have a structure similar to the LaCoO3 structure as mother compound. Solid-state and co-precipitation with aging treatment can produce LSCF with high purity. Meanwhile, there were still other phases in LSCFs which were synthesized by sol-gel and co-precipitation methods without aging treatment. Other phases that appear are estimated from the Co3O4 for co-precipitation method without aging treatment and Co3O4 and Fe2O3 for sol-gel method. The solid-state method is capable of producing particles with the highest crystallinity compared to other methods. The TGA results from LSCF with the sol-gel method and co-precipitation (without and with aging time) showed that the perovskite could be formed at temperature 650 °C. Characterization of LSCF particles with Scanning Electron Microscope (SEM) showed that all samples had irregular particle shapes, with uniformly small particle for sol-gel method, and the possibility of formation of large particle for co-precipitation method. However, Particle Size Analysis (PSA) analysis shows that in general, the co-precipitation method could produce smaller particle (particle size 1904.1 nm) than the solid-state method (particle size 2812.4 nm). [ABSTRACT FROM AUTHOR]

Graphical abstract M sp as a function the reduced temperature (T C - T)/ T C for samples with x = 0 (a) and x = 0.02 (b). The red lines are the linear fit of the function M sp (T) = M sp (0)[1 − T / T C ]β to the experimental data. Highlights • La 0.7 Ca 0.3 Mn 1-x Ni x O 3 (x = 0, 0.02) perovskites manganites are synthesized by auto-combustion. • Undoped and doped samples exhibit second-order phase transition. • The Ni-doping decreases the values of the Curie temperature. • Values of the critical exponents are close to those theoretically predicted by mean-field theory. Abstract Nanosized La 0.7 Ca 0.3 Mn 1-x Ni x O 3 (x = 0, 0.02) manganites were synthesized via the auto-combustion method. The critical behavior of these samples was then carefully investigated by analyzing the results of static magnetic measurements near their critical temperatures. The samples exhibited second-order phase transition, and the effect of Ni doping was to lower the critical temperature. The analysis of the experimental data was carried out by means of various techniques, such as modified Arrott plots, the Kouvel-Fisher method, and critical isotherm analysis, which revealed that the values of the critical exponents β, γ, and δ are close to those theoretically predicted by mean-field theory. By using the Widom scaling relation and the universal scaling hypothesis, the dependability of the obtained values of the critical exponents was confirmed. Moreover, the temperature dependence of the spontaneous magnetization was estimated from the analysis of the variation of the magnetic entropy change with the magnetization within the framework of mean-field theory. Interestingly, the spontaneous magnetization determined from the entropy change and that obtained from classical extrapolation of the Arrott curves displayed high concordance. These results strongly suggested that the interactions among spins in the investigated compound are long-range. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) perovskite micro/nanostructures have drawn considerable attention worldwide for their unique optoelectronic properties and promising applications in nanoelectronics and nanophotonics. In this article, syntheses of 2D propylammonium lead halide perovskite microstructures are reported. The iodine-containing perovskite exhibits a flower-like hierarchical morphology with the “petals” consisting of approximately vertical-crossing ribbons. This compound possesses the chemical formula (C3H7NH3)6Pb4I14, with the structure consisting of both corner-sharing and face-sharing PbI6 octahedra to complete the 2D network. The hydrogen-bonding interactions between organic group C3H7NH3+ and bilateral nearest-neighboring perovskite sheets are deemed to be responsible for this structure. By contrast, the lead bromide perovskite displays a plate-like morphology and bears the formula (C3H7NH3)2PbBr4, with its structure containing purely corner-sharing PbBr6 octahedra. Optical measurements indicate that a more evident 2D exciton feature can be observed in (C3H7NH3)2PbBr4 than in (C3H7NH3)6Pb4I14. For (C3H7NH3)2PbBr4, photoluminescence (PL) measurement displays a strong emission peak at 419 nm, stemming from free exciton transition. PL decay analysis of the free exciton in (C3H7NH3)2PbBr4 shows its lifetime of about 16.4 ns. Our successful syntheses and preliminary optical investigations on such 2D perovskite nanostructures offer a new material for research on the fundamental properties of 2D perovskites and their potential applications in optoelectronic devices. [ABSTRACT FROM AUTHOR]

Polycrystalline La0.9Sr0.1Cr1−xCoxO3 (0.0 ≤ x ≤ 0.4) solid solutions were synthesized by a sol-gel method using citric acid as chelating agent. Thermogravimetric and differential thermal analysis, Fourier-transform infrared spectroscopy, and X-ray diffraction (XRD) techniques are used to explore precursor decomposition and to establish adequate calcination temperature for the preparation of the polycrystalline. The samples obtained after calcination at 750 °C were characterized by several techniques. X-ray diffraction analyses reveal that that B-site doping of Co may lead to the transformation of its crystal structure from an orthorhombic to a rhombohedral phase, when Co content x ≥ 0.2. Scanning electron microscopy (SEM) shows that all samples have almost spherical nanoparticles with high crystallization. The increase in the fraction of the doped-Co leads to high agglomeration of particles while the porosity increases. Electrochemical measurements indicate that the catalytic activity toward methanol oxidation in alkaline solution is strongly influenced by cobalt doping. La0.9Sr0.1Cr0.6Co0.4O3-modified electrodes responded extremely well to methanol by giving high anodic current for methanol oxidation (over 46 mA cm−2 at 0.650 V vs Hg/HgO). [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A new 1,8-naphthalimide based fullerene derivative, PC 61 BNI was synthesized. • Molecular structure modification effect on device performance was explored. • Trge mapping by Kelvin probe forhe Inverted device fabricated with PC 61 BNI demonstrated PCE of 10.79%. • The best device with PC 61 BNI showed 44 mV higher Voc compared to the PC 61 BM. Abstract A new fullerene derivative, PC 61 BNI, was designed and synthesized in which [6,6]-phenyl C 61 -butyric acid methyl ester (PC 61 BM) was modified by replacing the methyl group with 1,8-naphthalimide (NI) to investigate the molecular structure modification effect on perovskite solar cell performance. Inverted perovskite solar cells were fabricated employing PC 61 BNI as an electron transport material (ETM) and its performance was compared with that of the device fabricated using PC 61 BM. Optical and electrochemical properties of the PC 61 BNI were characterized, and how NI substitution affects the solar cells performance was investigated. The photoluminescence quenching experiments confirmed efficient electron injection from perovskite film into PC 61 BNI layer. The lowest unoccupied molecular orbital (LUMO) energy level of PC 61 BNI (–3.75 eV) was found to be higher than that of PC 61 BM (–3.91 eV). The device fabricated with PC 61 BNI exhibited a power conversion efficiency (PCE) of 10.79% with photocurrent density (Jsc) of 20.23 mA/cm2, open-circuit voltage (Voc) of 1.078 V and fill factor (FF) of 0.497. [ABSTRACT FROM AUTHOR]

Nanomaterials are playing more and more important roles in modern industry, while the large-scale fabrication and dispersibility still need to be addressed. This report explores the uniform fabrication and morphology control of ultrafine BaTiO3 (BT) nanocrystals using a 'TEG-sol' method. By varying the reactant concentration, the obtained product sols, Ba/Ti ratios, structure and morphology of the nanocrystals are investigated. The results reveal that under low concentrations (0.4-0.8 mol/L), transparent sols with uniform BT nanocrystals are obtained. Increasing the concentration to higher than 1.0 mol/L, BT precipitates with abnormal large crystals are obtained. Moreover, the Ba/Ti ratio variation further reveals that the surface organics are critical to the control of crystal size and morphology. This investigation is potential to be extended to the synthesis of various perovskite nanocrystals. [ABSTRACT FROM AUTHOR]

Lead halide perovskite materials have shown strong promise in energy harvesting and generation over the past five years. However, their poor ambient stability and lead toxicity issues hinder optoelectronic applications. In the quest for alternatives, metal halide perovskites with lower toxicity and more stable metals have recently emerged. The divalent Pb2+ could be replaced with isoelectronic Sn2+, but Sn2+ tends to oxidize rapidly in presence of air to Sn4+, forming a defect in the structure. However, Sn2+‐based perovskites have been stabilized in 2D structures. Recently Sn4+ based halide perovskites nanocrystals with have been reported with poor luminescence. The replacement of Pb2+ with isoelectronic trivalent elements (Sb3+, Bi3+) results in A3B2X9 type defect‐order perovskite structure, which shows promises for optoelectronic applications. The perovskite nanocrystals of Sb, Bi have been reported in the form of dimers and layered structures. In addition to these, double perovskites, where two divalent Pb2+ are replaced with a monovalent and a trivalent cation have been reported very recently. In this Focus Review, we give a brief summary of different non‐lead perovskite nanocrystals starting from synthesis, characterization, stability, properties to applications, along with potential future directions. No Pb: The extraordinary performances of metal halide perovskites in light harvesting and generation have fueled research into lead‐free alternatives to reduce lead toxicity and improve perovskite stability. This Minireview gives a brief overview of the synthesis, characterization, applications, and future directions of recently reported non‐lead perovskites. [ABSTRACT FROM AUTHOR]

Manganite perovskite oxides exhibit a wide range of properties relevant for catalysis, energy conversion and spintronics. Such behaviors can be deeply modified at the nanoscale where confinement and surface effects may prevail. Interesting properties could then emerge from manganite perovskite nanocrystals, although their synthesis remains a challenge. The present study reports a versatile synthesis of manganite perovskite nanocrystals by using molten salts as high temperature liquids in the 600–750 °C range. Through X‐ray diffraction, X‐ray photoelectron spectroscopy, scanning and transmission electron microscopies, we show that many substitutions on the A perovskite site are within reach by applying the approach to La2/3Sr1/3MnO3, La2/3Ca1/3MnO3 and La1/3Pr1/3Ca1/3MnO3 cubic‐shape nanocrystals with diameter of 20, 22 and 38 nm, respectively. The magnetic properties of these nanocrystals are then investigated at 5 K, highlighting the coexistence of a ferromagnetic phase typical of the bulk, with disordered and non‐magnetic domains, which presumably arise from the nanoscale and surface effects. Manganese oxide perovskites are obtained for the first time as highly crystalline, well‐faceted nanocrystals. High temperature liquid‐phase syntheses in molten salts thus offer a nice playground to assess the impact of the nanoscale on the properties of these materials, as exemplified by the magnetic properties of three different manganites. [ABSTRACT FROM AUTHOR]

An array of hybrid lead halide CH3NH3Pb(Br/I)3 colloidal perovskites have been successfully synthesized by 532 nm laser irradiation of either pure lead halide CH3NH3PbX3 (X=Br−, I−) or mixed‐halide CH3NH3PbBr3‐xIx bulks, by using 2‐adamantylammonium iodide and/or 2‐adamantylammonium bromide as the source for varying the perovskite halide content as well as for confining the material to the nanoscale. Double agent: An array of hybrid lead bromide perovskite nanoparticles (emission from 528–730 nm) were successfully prepared by laser ablation of pure and mixed‐halide bulks in the presence of adamantylammonium halide with a dual role as confinement agent and halide source. [ABSTRACT FROM AUTHOR]

Nowadays, organo-lead halide is one of the most interesting materials for perovskite solar cells. This is because of its ease of fabrication, long absorption wavelength region, and long diffusion length. In this study, we investigated the bandgap tuning of hybrid mixed-halide perovskite films. The films were prepared by sequential two-step deposition technique, using 5-ammonium valeric acid iodide (5-AVAI), PbI2, and a mixture of CH3NH3I and CH3NH3Br as precursor solutions. The results confirmed the formation of 2D perovskites in the presence of 5-AVAI. The obtained films had higher moisture resistance, better surface coverage, and smaller grain size, compared to the films without 5-AVAI. With the introduction of Br− ions, the change in the lattice parameter was observed. The bandgap was also found to increase with increasing Br− content. [ABSTRACT FROM AUTHOR]

Abstract We have investigated the spin and orbital moments of Ir-based double perovskites with 5 d n (n = 3, 4, 5) states by local spin-density approximation with spin-orbital coupling and Hubbard correlation (LSDA+SOC+U). Our calculations reveal that the ratio of orbital to spin momentum L z / S z approaches to certain values for the double perovskites with different 5d n (n = 3, 4, 5) shell fillings. Based on d orbits, a spin-orbital coupling model with exchange splitting is proposed and it can well describe the ratio of angular momentums for the compounds. Our model calculations reveal that L z / S z is determined by the exchange splitting, spin-orbital coupling as well as the state of shell filling. Our model is well corroborated by the experiments and density-functional calculations. Highlights • Spin and angular momentums of the series of Ir-based double perovskites have been studied by LDA+U+SOC method. • Our calculations reveal that the L z / S z values approach to certain values for the 5 d n cations of Ir. • A d -orbit-based model was proposed to explain the results of density-functional calculations and the experiments. [ABSTRACT FROM AUTHOR]

In this paper we report about the particle size controlling factors on various perovskite metal oxide, XTiO3 (X = Ca, Sr, Ba, Pb), nanoparticles by hydrothermal synthesis in supercritical water of 400 °C and 30 MPa. Experiments were performed the developed flow reaction system. Characteristics of the product were performed by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy equipped with energy dispersive X-ray spectrometry (SEM-EDS) and nitrogen adsorption. The behavior of particle growth of perovskite metal oxides depended on A-site metal ions and the order of the particle size was Sr < Ca < Ba < Pb. The particle growth of perovskite metal oxide in supercritical water could be affected by solubility of A site ions. [ABSTRACT FROM AUTHOR]

Perovskite solar cells exhibiting ~ 14-15% efficiency were experimentally measured using current-voltage (I-V) and capacitance-voltage (C-V) techniques in order to extract material and device properties, and understand the action of photovoltaic (PV) operation. Deep analyses were carried out on dark- and illuminated I-V curves, and dark C-V curves. Results were compared with those of graded bandgap solar cells fabricated on inorganic n-type window layers. These analyses according to a physicist's point of view lead to understand the perovskite solar cell as a graded bandgap solar cell built on a p-type window layer. I-V and C-V results show very similar behaviour and the principle of PV action is identical. Once the stability issues with perovskites are solved, these devices have very high potential of producing next generation solar cells reaching at least mid-20% efficiency values. [ABSTRACT FROM AUTHOR]

Abstract This paper reports combustion synthesis of Gd 2 NiMnO 6 nanostructures (GNMO NSs), for the first time, through reaction between metal nitrates in the presence of different saccharides, as capping and reducing agents. Analysis of XRD, FT-IR, EDS, along with TEM and SEM images and also VSM and DRS spectra were applied to study the NSs. The VSM showed an antiferromagnetic behavior. The DRS spectroscopy ascertained semiconducting behavior of GNMO NSs with E g = 3.05 eV for optimum sample prepared in the presence of glucose at 1000 °C. The CV was used to investigation of electrochemical property of the NSs. For the first time, the photocatalytic behavior of the GNMO NSs was evaluated, using the degradation of organic dyes under UV irradiation. The photodegradation of EDT was almost similar to that of ES, except for initial times of the irradiation. The degradation percentage of EBT and ES in the presence of GNMO NSs was large, whereas that of MV was little in the time range. Graphical abstract Image 1 Highlights • GNMO NSs were synthesized through a simple combustion method, for the first time. • Saccharides were used as capping and reducing agents. • Effect of different saccharides and temperature in this synthesis was investigated. • This work is the first report of photocatalytic study of the GNMO NSs. • Photocatalytic, electrochemical, optical, magnetic properties of NSs were studied. [ABSTRACT FROM AUTHOR]

In this work, two dry and direct routes for LaCoO3 perovskite synthesis are presented: solid-state synthesis and high-energy ball milling. These synthesis routes are clean and do not make use of materials other than the reaction precursors. The following methods for physical characterization have been applied: X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive electron diffraction (EDS). The solid-state synthesised powders are polycrystalline within a single-phase, proving that the preparation method is efficient to produce LaCoO3 perovskites. The high-energy ball-milling method produces finer powders. The heat-treatment of these powders leads to high crystalline quality. Both powders have the same stoichiometry. The developed methods have lower preparation temperatures, simpler synthesis protocols and less expensive precursors, leading to energy and price savings. [ABSTRACT FROM AUTHOR]

Flexible solar cells have drawn wide attention because of their high photoelectric conversion efficiency, convenient preparation, excellent bendability and lower cost advantages. This paper introduces the effect of mesoporous layer on the morphology of CH3NH3PbI3 films. The uniformity and optical transmittance of the different films were also studied in detail. By adjusting the ratio of TiO2 and ZrO2, mesoporous structure of CH3NH3PbI3 perovskite solar cells were prepared by two-step spin coating. The fabricated films were investigated by XRD, SEM and spectrophotometer. The results indicate that perovskite layers have good surface morphology, density and coverage with TiO2 and ZrO2 composition ratio of 1:1. These well-structured thin films lay a good foundation for the preparation of high performance flexible perovskite solar cells. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Solid-state perovskite nanocrystals are promising coherent light sources, as there is optical feedback within the crystal structure. In order to utilize the high performance of perovskites for on-chip applications, or observe new physical phenomena, these crystals must be integrated with pre-fabricated electronic or photonic structures. However, the material's fragility has made the deterministic transfer a great challenge thus far. Here, we report the first deterministic transfer of perovskite nanocrystals with sub-micron accuracy. Cesium lead halide (CsPbI 3) nanocrystals were directly synthesized on flexible polydimethylsiloxane (PDMS) stamps via chemical vapor deposition (CVD) and subsequently transferred onto arbitrary substrates/structures. We demonstrated the transfer of a CsPbI 3 crystalline nanoplate (NP) onto an 8 µm fiber core and achieved single-mode whispering gallery mode lasing. Our method can be extended to a variety of other arbitrary substrates (e.g., electrodes, photonic structures, micromechanical systems), laying the foundations for previously unattainable opportunities in perovskites-based devices. [ABSTRACT FROM AUTHOR]

Abstract X-modified magnetite (XFe 2 O 4 ; X = Cr, Mn, Fe, Co or Ni) was synthesized from goethite reduction, and inserted into the Fe-vacancy of perovskite (BiFeO 3), via microbial Fe3+→Fe2+ reduction by Shewanella (e.g. Shewanella oneidensis MR-1 and Shewanella putrefaciens CN32). We demonstrated that the average adsorption intensities of nine toxic trace metals (Cr3+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pb2+, and Hg2+), in Freundlich mode were 8.29–10.79 multiples higher than that in Langmuir mode, being more competitive than previously reported values. The fluorescence quenching is attributed to the orbital hybridization of molecular oxygen activation and trace metal (M) ions, which weakens the X2+-O-Fe3+-O-(Fe3+) coupling orbital. In addition Shewanella putrefaciens CN32 creates more oxygen vacancies to modify Ni↓-Fe↓-O↑ d*-p hybridized orbitals for enhancing the local spin-orbit coupling with Cd-4d10. This design idea can be extended to other direct biosynthetic magnetite-perovskite as highly efficient toxic trace metal removal agents. [ABSTRACT FROM AUTHOR]

Tin (Sn ^2+ ) and strontium (Sr ^2+ ) are potential replacements to lead (Pb ^2+ ) in perovskite synthesis since Sn is on the same IVA group in the periodic table as Pb while Sr is a promising alternative according to Goldschmidt’s rules and quantum mechanical analysis. The crystal radii of their ions are also nearly identical with Pb ^2+ = 1.33 Å, Sn ^2+ = 1.36 Å, and Sr ^2+ = 1.32 Å. In this study, both Sn and Sr were explored in transforming calcite, a polymorph of calcium carbonate (CaCO _3 ) into a leaving group in the first step of a sequential ion-exchange reaction towards perovskite formation. Instead of forming the intermediate tin carbonate (SnCO _3 ), the reaction resulted in the formation of gypsum or calcium sulfate dihydrate (CaSO _4. 2H _2 O) and Sn in the form of oxides. These oxides, however, are useful especially when these are in the form of tin dioxide-coated CaCO _3 shell-core structures—having demonstrated flame retardant and smoke suppressant properties. On the other hand, calcite was successfully transformed into strontium carbonate (SrCO _3 ) or strontianite through the cation exchange reaction. X-ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS) were used to observe the resulting materials and understand the transformation of both Placuna placenta (or Capiz) shells and single-crystal calcite from the ion-exchange reactions.

Polycrystalline material of double perovskite Dy2NiMnO6 was successfully synthesized by a high-temperature solid-state reaction method. Preliminary X-ray investigation established the formation of compound with monoclinic structure. The material exhibits dielectric relaxation supported by modified Curie-Weiss law and a Vogel-Fulcher law. Impedance spectroscopy of the compound was analyzed by impedance analyzer in the range of frequency (1 kHz-1 MHz) and temperature (25-250 °C) that confirming non-Debye type of relaxation. The presence of different kind of charge carriers along with NTCR behavior of the material was found from the AC conductivity study. It is noticed that oxygen vacancies are the responsible factor for high temperature conduction process and dynamics of polarization of system. From these results, it may be concluded that this compound may have extreme potential applications at different temperatures. [ABSTRACT FROM AUTHOR]