Retention of toxic metals/metalloids like arsenic via mineral-water interaction plays a crucial role in the environmental behavior of pollutants. However, the influence of mineral crystallinity on the retention of toxic elements, the evolution of liquid composition, and the interaction mechanism are poorly understood. This study investigated the interaction between As(V) and calcium phosphate (CaP) under oxic conditions with varying crystallinities, particularly amorphous CaP (ACP), across varying As(V) concentrations and pH conditions. Results revealed that the amorphous phase substantially influenced As(V) fate, with the As(V) retention potential of ACP and poorly crystalline hydroxylapatite (HAP) being 13.65 and 12.61 times higher than highly crystalline HAP, respectively. As(V) retention involves the dissolution of ACP and the recrystallization of As(V)-substituted HAP, correlated with three distinct ACP transformation stages during recrystallization. The lower pH (7.5) facilitated ACP dissolution, and the elevated Ca2+ concentration enhanced the volume of CaP recrystallization. Conversely, higher pH levels (8.0, 8.5, and 9.0) promoted a higher degree of recrystallization, evidenced by reduced residual Ca2+ levels after 48 hrs (post-crystallization stage). Meanwhile, As-bearing CaP forms with greater competition between PO43- and AsO43- at higher initial As(V) concentrations than lower ones. Additionally, lattice distortion, increases in species of surface bond groups, and reduced crystallinity were observed in the As(V)-bearing CaP product. Overall, this study underscores the pivotal role of ACP and its poorly crystalline counterparts in arsenic retention through the dissolution-recrystallization mechanism.

Hydroxylapatite (HAp), owing to its excellent biocompatibility, is a promising carrier for lanthanide ions to encourage antibacterial activity. However, hydroxylapatite powder would still require modification to ensure the optimal integration of antibacterial characteristics. In this study, Sm-doped nano-hydroxylapatite (SmHAp) was synthesized by spontaneous mineralization of amorphous SmHAp precursors, which ensures a homogeneous distribution of Sm3+ within bulk SmHAp. Powder X-ray diffraction and its Pawley fitting results for SmHAp indicate the lattice substitution of Ca2+ with Sm3+, resulting in the lattice distortion in SmHAp compared to pure HAp. Meanwhile, polymer-encapsulated Sm-doped nano-hydroxylapatite composite (p_SmHAp) was synthesized by a dual-step polymerization involving UV curing of an outer crust and heat treatment for bulk reaction completion. Irgacure 2959 and a toluene solution of AIBN were used as catalysts for the radical polymerization process. The antibacterial property of p_SmHAp was evaluated by observing the growth of Sporosarcina pasteurii (ATCC 11859) both in the solid and the liquid medium, correlating with the Sm fraction and SmHAp’s crystallinity in p_SmHAp. These bacteriostatic rings' diameters exceed 20 mm, demonstrating that p_SmHAp with a SmHAP/p_SmHAp mass ratio of 0.1 and Sm/(Ca+Sm) molar ratio of 0.05−0.1 effectively releases Sm3+, serving as a strong antibacterial agent.

Traditional 3D perovskites, being remarkably effective in solar cells and light-emitting diodes (LEDs), exhibit poor stability under illumination and moisture, limiting their real-life applications. Recent advancements in perovskite-based devices have utilized combinations of 2D and 3D perovskites to improve stability. However, high ion mobility can lead to the formation of quasi-2D phases at interfaces during fabrication, whose behavior remains unclear. Previous studies indicate that quasi-2D perovskites are less stable and may transform into 3D phases under illumination, but the underlying mechanisms have yet to be investigated. In this work, the light-induced transformation of quasi-2D phenylethylammonium cesium lead bromide PEA2Csn-1PbnBr3 n +1 perovskite is demonstrated to stable 3D CsPbBr3 perovskite. The process is initiated by light excitation, which triggers a reaction with surrounding moisture and oxygen molecules. PbO and Pb(OH)2 species form within the material which passivate defects and significantly enhance the photoluminescence and stability of the 3D phase. The simple synthesis method, followed by UV treatment, provides a direct method to stable and luminescent 3D perovskite, making it promising for solar cell, LEDs and photodetector applications.

Barium zirconium trisulfide (BZS) is a three-dimensional (3D) perovskite with optoelectronic properties suitable for photovoltaic (PV) and light-emitting diode (LED) applications that is conventionally reported in the orthorhombic Pnma (62) symmetry. Synchrotron X-ray diffraction, thermal analysis, and Raman and absorption spectroscopy revealed three high-temperature polymorphs that appear when BZS is heated in air prior to complete oxidation (BaZrS3 + 5O(2) -> BaSO4 + ZrO2 + 2SO(2)up arrow) at 700 degrees C with the approximate stability ranges: BaZrS3 IV Pnma (62) T < 400 degrees C BaZrS3 III Cmcm (63) 400 degrees C <= T <= 500 degrees C BaZrS3 II 14/mcm (140) 500 degrees C <= T <= 700 degrees C Differential scanning calorimetry (DSC) revealed exothermic features accompanying the IV -> III and III -> II phase changes. Furthermore, the direct band gap varied inversely with temperature with distinct energies for each polymorph (1.84 eV <= IV <= 1.65 eV; 1.65 eV <= III <= 1.54 eV; 1.54 eV <= II <= 1.52 eV). Raman spectroscopy found that polymorphic changes up to 600 degrees C were reversible with bands characteristic of BaZrS3 IV entirely restored upon cooling to room temperature (RT). This more complete understanding of BSZ polymorphism provides a basis for producing crystallochemical variants with enhanced optoelectronic properties under ambient conditions.

The formation of As(V) substituted hydroxylapatite (HAP) has a vital influence on the fate of As(V) in the environment. However, despite growing evidence showing that HAP crystallizes in vivo and in vitro with amorphous calcium phosphate (ACP) as a precursor, a knowledge gap exists concerning the transformation from arsenate-bearing ACP (AsACP) to arsenate-bearing HAP (AsHAP). Here we synthesized AsACP nano-particles with varied As contents and investigated the arsenic incorporation during their phase evolution. The phase evolution results showed that the transformation process of AsACP to AsHAP could be divided into three Stages. A higher As(V) loading significantly delayed the transformation of AsACP, increased the distortion degree, and decreased the crystallinity of AsHAP. NMR result showed that the PO43- tetrahedral is geometrically preserved when PO43- is substituted by AsO43-. From AsACP to AsHAP, the As-substitution led to the transformation inhibition and As(V) immobilization.

A mixed passivation strategy is deployed to produce monodisperse and pure CsPbBr3 nanocrystals under ambient condition via post treatment using ZnBr2 in mixed organic solvents. This room temperature synthesis route provides precise size and shape control, and colloidal nanocubes or nanospheres can be obtained depending on the choice of organic solvents. Any secondary phases’ nucleation was inhibited. The ZnBr2 can reduce the Br− vacancies at the surface termination layers, thus enhancing their properties. This approach can potentially offer a cheap and viable route for perovskite nanocrystals in optical and electrical devices.

The renewed interest in shape memory and toughened ceramics for small‐scale applications makes the relationship between the chemistry of the ceramics and martensitic transformation temperatures (forward and reverse temperatures M s and A s) of paramount importance. Dependence of transformation temperatures of the ceramics with shape memory effect and/or martensitic phase change on valence electron ratio (VER), number of valence electrons (e v), and average atomic number of the ceramics (Z) is investigated. Depending on chemical composition, the ceramics have average numbers of valence electrons (4.571 ≤ e v ≤ 5.667), Z = 13–29.333, and VER in the range of (0.17–0.44). A clear correlation of transformation temperatures to VER for most ceramics is found. M s and A s both decrease with increasing VER. Aliovalent doping alters e v and makes it influential in controlling the transformation temperatures. The influence of VER, e v, Z, and the suppressive effect of oversized solutes on M s is addressed.

Potassium substituted double perovskite nanocrystals of the form Cs2KxAg1−xInCl6:Bi (x = 0–1) exhibit improved PLQY behaviour and structural diversity.

Perovskite-related materials show very promising properties in many fields. Pb-free perovskites are particularly interesting, because of the toxicity of Pb. In this study, hybrid double perovskite MA2KBiCl6 (MA = methylammonium cation) was found to have interesting variable temperature behaviours. Both variable temperature single crystal X-ray diffraction, synchrotron powder diffraction, and Raman spectroscopy were conducted to reveal a rhombohedral to cubic phase transition at around 330 K and an order to disorder transition for inorganic cage below 210 K.

The transformation product of amorphous calcium phosphate without inhibitors at room temperature is monoclinic HAp rather than the more common hexagonal HAp.

Methylammonium (MA+) lead halide perovskites (MAPbX3) have been widely investigated for photovoltaic applications, with the addition of Cs improving structural and thermal stability. This study reports the complete A site miscibility of Cs+ and MA+ cations in the lead chloride and lead bromide perovskites with nominal stoichiometric formulae (CsxMA1-x)Pb(Cl/Br)3 (x = 0, 0.13, 0.25, 0.37, 0.50, 0.63, 0.75, 0.87, 1). These suites of materials were synthesized mechanochemically as a simple, cost-effective synthesis technique to produce highly ordered, single phase particles. In contrast to previous studies using conventional synthetic routes that have reported significant solubility gaps, this solvent-free approach induces complete miscibility within the dual cation Cs+/MA+ system, with the resultant structures exhibiting high short-range and long-range atomic ordering across the entire compositional range that are devoid of solvent inclusions and disorder. The subtle structural evolution from cubic to orthorhombic symmetry reflecting PbX6 octahedral tilting was studied using complementary high resolution TEM, powder XRD, multinuclear 133Cs/207Pb/1H MAS NMR, DSC, XPS and UV/vis approaches. The phase purity and exceptional structural order were reflected in the very high resolution HRTEM images presented from particles with crystallite sizes in the ∼80-170 nm range, and the stability and long lifetimes of the Br series (10-20 min) and the Cl series (∼30 s-1 min) under the 200 kV/146 μA e- beam. Rietveld refinements associated with the room temperature PXRD study demonstrated that each system converged towards single phase compositions that were very close to the intended target stoichiometries, thus indicating the complete miscibility within these dual cation Cs+/MA+ solid solution systems. The multinuclear MAS NMR data showed a distinct sensitivity to the changing solid solution compositions across the MAPbX3-CsPbX3 partition. In particular, the 133Cs shifts demonstrated a sensitivity to the cubic-orthorhombic phase transition while the 133Cs T1s exhibited a pronounced sensitivity to the variable Cs+ cation mobility across the compositional range. Variable temperature PXRD studies facilitated the production of phase diagrams mapping the Cs+/MA+ compositional space for the (CsxMA1-x)PbCl3 and (CsxMA1-x)PbBr3 solid solution series, while Tauc plots of the UV/vis data exhibited reducing bandgaps with increasing MA+ incorporation through ranges of cubic phases where octahedral tilting was absent.

This investigation has characterised the structure and surface chemistry of CsPbBr3 nanocrystals with controlled diameters between 6.4 to 12.8 nm. The nanocrystals were investigated via a thorough 133Cs solid state NMR and nuclear relaxation study, identifying and mapping radially-increasing nanoscale disorder. This work has formalised 133Cs NMR as a highly sensitive probe of nanocrystal size, which can conveniently analyse nanocrystals in solid forms, as they would be utilised in optoelectronic devices. A combined multinuclear solid state NMR and XPS approach, including 133Cs-1H heteronuclear correlation 2D (HETCOR) NMR, was utilised to study the nanocrystal surface and ligands, demonstrating that the surface is Cs-Br rich with vacancies passivated by didodecyldimethylammonium bromide (DDAB) ligands. Furthermore, it is shown that a negligible amount of phosphonate ligands remain on the powder nanocrystal surface, despite the key role of octylphosphonic acid (OPA) in controlling the colloidal nanocrystal growth. The CsPbBr3 NCs were shown to be structurally stable under ambient conditions for up to 6 months, albeit with some particle agglomeration.

Two-dimensional (2D) phenylethyl ammonium (PEA(+))-methyl ammonium (MA(+)) lead iodide ((PEA)(2)(MA)[Pb2I7]) hybrid perovskite exists as temperature-dependent dimorphs exhibiting an ill-defined phase transition occurring over the 150-200 K range. Raman scattering, photoluminescence, optical absorbance and solid state MAS NMR spectroscopic methods are employed to investigate the structural complexity, disorder and structure/function of this system. The Raman and H-1 MAS NMR data indicate that the lower bounds of the phase transition at similar to 150 K are characterised by attenuated rotational modes and slower motional dynamics throughout the disordered MA(+) organic sublattice, inducing a strengthening of the MA(+)MIDLINE HORIZONTAL ELLIPSISI hydrogen bonds and a 5 meV increase in the excitonic and photoluminescence energies. It is evident that different recombination mechanisms are dominant for the room temperature and low temperature phases reflecting the importance of MA(+) dynamics in the optical properties of the material. Single crystal X-ray studies are unable to position the organic cations within the Pb2I7 framework; however, H-1/C-13 MAS NMR measurements describe elements of local structural disorder based on conformational isomerism within the PEA(+) sublattice. Concomitant I- and Pb2+ migration and [Pb2I7](3-) framework defects create stacking disorder, dislocations and dispersed octahedral tilting leading to additional disorder and distributed MA(+) and PEA(+) cation dynamics.

Hybrid organic-inorganic lead halide perovskite nanoparticles are promising candidates for optoelectronic applications. This investigation describes the structural and optical properties of MA x Cs1-x PbBr3 mixed cation colloidal nanoparticles spanning the complete compositional range of Cs substitution. A monotonic progression in the cubic lattice parameter (a) with changes in the Cs+ content confirmed the formation of mixed cation materials. More importantly, time-resolved photoluminescence (TRPL) revealed the optimized 13 mol% Cs nanoparticle composition exhibits the longest charge carrier lifetime and enhancement in radiative pathways. This sample also showed the highest photoluminescence quantum yield (PLQY) of ∼88% and displays ∼100% improvement in the PLQY of pure MAPbBr3 and CsPbBr3. Prototype LEDs fabricated from MA0.87Cs0.13PbBr3 were demonstrated.

While metal-organic frameworks (MOFs) exhibit excellent potential in extensive catalytic reactions, predictably synthesizing MOF nanoparticles (NPs) with desired and uniform sizes remains a great challenge. Here, a mild and efficient ultrasound-assisted synthetic method has been developed to prepare ZIF-8, ZIF-67, and Co/ZIF-8 with well-designed particle size and morphology. By adjusting the cobalt content doped into a heterometallic ZIF-8 structure, tunable particle sizes ranging from 35 nm to over 300 nm have been achieved, resulting from the differences in nucleation and growth rates of zinc and cobalt ZIFs. Impressively, this as-obtained bimetallic Zn/Co-ZIF shows hierarchical porous structure with modified physicochemical properties, leading to a change of nitrogen adsorption-desorption characteristics. In addition, when used as a heterogenous catalyst, the bimetallic Co-doped ZIF-8 is demonstrated to have both enhanced catalytic performance for the activation of peroxymonosulfate (PMS) in organic dye degradation compared to pure ZIF-8, as well as superior structural stability, when compared to monometallic ZIF-67. This work provides a novel strategy for the predictable design and controlled fabrication of bimetallic MOF nanostructures with desired structures and compositions.

Metal lead halide perovskite nanocrystals have emerged as promising candidates for optoelectronic applications. However, the inclusion of toxic lead is a major concern for the commercial viability of these materials. Herein, we introduce a new family of non-toxic reduced dimension Rb2CuX3 (X = Br, Cl) colloidal nanocrystals with one-dimensional crystal structure consisting [CuX4]3- ribbons isolated by Rb+ cations. These nanocrystals were synthesised using a room-temperature method under ambient conditions, which makes them cost effective and scalable. Phase purity quantification was confirmed by Rietveld refinement of powder X-ray diffraction and corroborated by 87Rb MAS NMR technique. Both samples also exhibited high thermal stability up to 500 °C, which is essential for optoelectronic applications. Rb2CuBr3 and Rb2CuCl3 display PL emission peaks at 387 nm and 400 nm with high PLQYs of ∼100% and ∼49%, respectively. Lastly, the first colloidal synthesis of quantum-confined rubidium copper halide-based nanocrystals opens up a new avenue to exploit their optical properties in lighting technology as well as water sterilisation and air purification.

Inorganic cesium lead halide perovskite nanocrystals are promising materials for optoelectronic applications as they exhibit high thermal stability alongside precise color tunability and high color purity; however, their optical properties are degraded by surface defects. This work demonstrates a room temperature synthesis of CsPbBr3 nanocrystals facilitating in situ surface passivation via the incorporation of Zn2+ cations. The facile incorporation ZnBr2+ into the precursor solution facilitates Zn2+ and Br- substitution into the nanocrystal surface/subsurface layers to induce passivation of existing Pb2+ and Br- vacancies and increase the photoluminescence quantum yield from similar to 48 to 86%. The XPS and solid-state H-1 MAS NMR techniques show that the key modification is a reduction of the octylamine:oleic acid ratio leading to a near-neutral surface charge; this is accompanied by the appearance of larger nanosheets and nanowires observed by quantitative powder XRD and HR-TEM. The suitability of these perovskite nanocrystals for electrically driven applications was confirmed by the fabrication of light-emitting diodes, which demonstrate that the in situ Zn2+ passivation strategy enhanced the external quantum efficiency by similar to 60%.

Novel Cs-containing triple cation perovskite nanocrystals produce high-performance LEDs as a result of improved surface passivation and environmental stability.

Single-phase apatite-type materials containing simulated radioactive liquid waste (Cs, Sr, REE) were synthesized by conventional solid-state reaction at the relatively low temperature of 700 degrees C. The products consisted of columnar crystallites typical of apatite materials. Mass loss stabilized at 700 degrees C with near quantitative retention of Cs confirming that evaporation of this volatile element was negligible.

Inorganic metal halide perovskite nanocrystals (NCs) are promising materials for emission-based applications; however, the inclusion of toxic lead may limit their commercial viability. This paper describes two cesium cupriferous iodides as nontoxic alternatives to lead containing perovskites. These nanocrystals were synthesized with tailored composition and morphology by a hot-injection colloidal route to produce hexagonal nanoplates (NPs) of blue-emitting Cs3Cu2I5 and nanorods (NRs) of yellow-emitting CsCu2I3. Phase purity was confirmed by Rietveld refinement of X-ray powder diffraction patterns and solid state 133Cs MAS NMR with both compounds exhibiting high thermal stability suitable for optoelectronic technologies. Phase mixing allows linear tuning of Commission Internationale de l’Eclairage (CIE) coordinates from (0.145, 0.055) to (0.418, 0.541) such that a 1:8 molar ratio of Cs3Cu2I5 NPs and CsCu2I3 NRs yields white emission, while the 133Cs MAS NMR demonstrates that these photophysical effects are not attributed to any changes in the Cu oxidation state.