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The document is a contents list for the journal CrystEngComm. It provides information about the articles and papers included in the issue, as well as the authors and their research topics. The journal focuses on the design and understanding of solid-state and crystalline materials. The document also mentions the Royal Society of Chemistry, which is a leading chemistry community that connects the world with the chemical sciences. [Extracted from the article]

The document is a contents list for the journal CrystEngComm, which focuses on the design and understanding of solid-state and crystalline materials. It is published by the Royal Society of Chemistry, a leading chemistry community. The contents list includes various papers and communications on topics such as crystal forms of bilirubin, distribution of basal plane dislocations in SiC single crystals, and synthesis of charge transfer cocrystals. The document also mentions approved training courses offered by the Royal Society of Chemistry. [Extracted from the article]

As a new generation of photoelectric materials, organic-inorganic halide perovskites have been widely used in photodetectors, solar cells and other fields, but most of the current mainstream applications are thin film materials. Compared with polycrystalline thin films, perovskite single crystals have fewer grain boundaries and relatively stable electron and hole transport, and are ideal materials for optoelectronic devices. To realize the controllable growth of CH3NH3PbBr3 (MAPbBr3) crystals, understand their growth mechanism, and reflect the inherent physical and chemical properties of the material, a new type of internal growth temperature control and external circulation cooling growth system was developed in this paper, which can accurately control the temperature change during crystal growth. The size of the grown MAPbBr3 single crystal reaches 62 × 58 × 23 mm³, which is the largest single crystal reported to date. The measured single crystal absorption cut-off edge, optical band gap, and carrier lifetime are superior to the traditional simple inverse temperature crystallization (ITC) method, which will help its deep applications in photovoltaics, optoelectronics, and X-ray imaging. [ABSTRACT FROM AUTHOR]

Viologen is capable of generating radicals in response to an applied stimulus, giving it an abundance of stimuli responsive properties. However, the radical state of viologen is often unstable, which hinders further studies on the radical properties of viologen. In this paper, the salicylhydrazide group was chosen as a donor group to bond with mono-substituted bipyridyl groups to obtain three novel D–A type viologen compounds. The compounds were harvested and characterized by X-ray single crystal diffraction, optical spectroscopy, EPR and DFT calculation, etc. The results show that compounds 1–3 adopt certain free radical states at room temperature under ambient light, which may be attributed to the electron-donating properties of the salicylhydrazide group and the degree of system conjugation. In addition, compound 1 has a hydrochromic property and compounds 2 and 3 have photocurrent effects under UV radiation. [ABSTRACT FROM AUTHOR]

CTGS crystals are widely used in the field of high-temperature piezoelectricity because of their excellent piezoelectric properties. In this paper, the Ca2+ lattice of CTGS crystals is replaced by Sr2+ with a larger radius to improve their piezoelectric properties. (Sr0.2Ca0.8)3TaGa3Si2O14 and Ca3TaGa3Si2O14 single crystals with a diameter of 25 mm were grown using the vertical Bridgman method. The full width at half maximum (FWHM) of X-ray rocking curves of SCTGS and CTGS crystals are 57.6′′ and 22.3′′, respectively. It was found that the thermal properties of SCTGS crystals, such as specific heat, thermal diffusion and thermal conduction, are slightly lower than those of CTGS crystals. At room temperature, the dielectric permittivity ε T11 increased from 18.59 to 18.78, and the piezoelectric coefficient d11 also increased from 4.22 pC N−1 to 4.54 pC N−1. The electrical resistivities of the X-cut plates of SCTGS and CTGS crystals are approximately 3.78 × 107 Ω cm and 2.40 × 107 Ω cm at 800 °C, respectively. Therefore, SCTGS will be a promising candidate piezoelectric material in the field of high-temperature sensing. [ABSTRACT FROM AUTHOR]

This paper focuses on the generation and transformation of defects associated with subsurface damages (SSDs) in seed crystals during the physical vapor transport (PVT) growth of 4H-SiC crystals. SSDs in the 4H-SiC seed crystal were first revealed and labeled through photo-chemical etching. After 30 min of PVT growth on the 4H-SiC seed crystal, we found that ridge-like substances with a height ranging from 0.2 to 1.5 μm were formed in the region above the SSDs in the 4H-SiC seed crystal. Raman spectra analysis indicated that these ridge-like substances were 4H-SiC under tensile strain. We then continued the PVT growth to obtain a 4H-SiC boule and carried out a wafering process to obtain 4H-SiC single-crystal wafers. For the bottom wafer, above the 4H-SiC seed wafer, the full width at a half maximum (FWHM) of the rocking curves of the region above the SSDs of the seed wafer was higher than that in the other regions, indicating that the SSDs degrade the crystalline quality of 4H-SiC single crystal. The average value of the FWHM of the rocking curves of the top wafer became lower than that of the bottom wafer, indicating that the effect of SSDs gradually recovers. Molten-KOH etching indicated that SSDs in the 4H-SiC seed crystal give rise to the formation of low-angular grain boundaries (LAGBs) that consist of a wall of threading edge dislocations (TEDs) in 4H-SiC single crystals. [ABSTRACT FROM AUTHOR]

The sesquioxide Lu2O3 possesses superior physical and chemical properties and emerges as a promising host material for high-power laser applications. However, Lu2O3 has an extremely high melting point, making it difficult to prepare large-size and high-quality crystals. In this paper, we report the growth of a Yb:Lu2O3 crystal with dimensions of Φ50.7 × 43.0 mm3 using the temperature gradient technique (TGT) combined with the directional solidification technique. The full width at half maximum (FWHM) of the high-resolution X-ray rocking curve of the crystal was determined to be 58.76 arcsec. Additionally, the optical homogeneity root mean square (RMS) was 10−5. The thermal properties, spectroscopic characterization, and continuous wave (CW) laser operation of Yb:Lu2O3 crystal were systematically studied. The results demonstrate the efficacy of the TGT as a novel approach for growing large-sized Lu2O3 crystals of exceptional quality. [ABSTRACT FROM AUTHOR]

Rare-earth orthoferrites have attracted intensive attention in the last few years for their abundant physical capabilities. In the present paper, a Nd3+ doped Dy0.9Nd0.1FeO3 (DNFO91) single crystal with high quality was grown by an optical floating zone method, and the magnetic properties have been investigated. We report an intriguing hybrid magnetic configuration Γ4+3 consisting of Γ4(Gx, Ay, Fz) and Γ3(Cx, Fy, Az), and it has a non-zero spontaneous magnetic moment along both the b-axis and c-axis. With lowering the temperature, the DNFO91 crystal experiences two continuous spin reorientation transitions from Γ4+3 to Γ2 at 45 K and finally to Γ1 below 43.8 K; here, Γ2 is an incomplete metastable phase transition induced by a magnetic field and disappears at 5000 Oe. Further research directly distinguished the rare-earth ion contributions for the first time, the magnetization along the b-axis originates from Nd3+ while that along the a-axis comes from Dy3+, and the relative strength can be further manipulated with an applied magnetic field. An exchange bias behavior was also observed in the M–H curves, revealing the exchange interaction between Dy3+/Nd3+ sublattices and Fe3+ sublattices. These features of single-crystal DNFO91 can help understand the influence of rare-earth doping on the magnetic structure and physical phenomenon in RFeO3, and this crystal has great application potential. [ABSTRACT FROM AUTHOR]

A Cd1−xMgxTe crystal is considered an ideal room temperature radiation detector material due to its excellent opto-electrical properties. In this paper, three large Cd0.95Mg0.05Te ingots with a diameter of 30 mm and a length of more than 100 mm were successfully grown by the modified vertical Bridgman method under different excess Te conditions (0.5 at%, 1.0 at% and 1.5 at%). The results showed that the as-grown Cd1−xMgxTe crystals have cubic zinc-blende structures. The band gap of the crystals ranged from 1.43 eV to 1.52 eV, the density of Te inclusions ranged from 2.7 × 103 cm−2 to 1.0 × 105 cm−2, the resistivity ranged from 8.22 × 106 Ω cm to 1.51 × 1010 Ω cm, and the IR transmittance ranged from 33% to 60%. With the increase of excess Te, the band gap, crystal resistivity and infrared (IR) transmittance decreased, and the density of Te inclusions increased. The analysis of the low temperature photoluminescence (PL) and Raman scattering spectra indicated that the crystal quality deteriorated gradually with the increase of excess Te. The crystal grown under 0.5 at% excess Te conditions had the best optical and electrical properties. [ABSTRACT FROM AUTHOR]

The fact that the polymorphic outcome of crystallization is the result of the interplay between the relative thermodynamic stability and nucleation kinetics is well known. This paper presents the synthesis of 2,5-bis(3-bromophenyl)furan (MBPF), for which three polymorphic structures were obtained. The studies included: investigations of three polymorphic structures of this compound using single crystal X-ray diffraction, UV–Vis spectroscopy, circular dichroism spectroscopy, and theoretical approaches. The most important experimental result is the solvent effect on the MBPF conformation stability and in consequence on the crystal growth of the metastable phase. [ABSTRACT FROM AUTHOR]

In this paper, large single crystals of diamond were synthesized in a pure Co–C system at 5.6 GPa and 1450–1470 °C. The diamond morphology, nitrogen content, and Co-related optical centres were investigated in depth. The results show that the diamonds are mostly bicrystalline or polycrystalline, with different surface defects, and the grown single crystals exhibit an octahedral morphology, with primarily {111} faces. The colour of the diamonds is brownish green-yellow and the nitrogen content is up to 980 ppm. The photoluminescence (PL) spectra show the presence of Co–V centres at 623 nm (V3Co2)0 and 843 nm (V1Co1+) in the diamonds. The intensity of Co-related optical centres at 623 nm and 843 nm gradually decreased with increases in the annealing temperature, and finally disappeared. Interestingly, Co–N complex defects appeared at 545 nm and 581 nm after annealing at 1700 °C, and the 524 nm Co–N complexes only appeared when the nitrogen almost completely aggregated after annealing up to 1800–1900 °C, and their intensity gradually increased with increasing annealing temperature. Furthermore, when nitrogen was removed from the growth system, the Co-related optical centres did not appear in the type IIa diamonds before and after annealing, which indicates that nitrogen impurities play an important role in the formation of Co-related optical centres. [ABSTRACT FROM AUTHOR]

Halide perovskites are among the most attractive research hotspots in optoelectronic applications due to their excellent luminescence properties. In this paper, Li+ was successfully incorporated into a one-dimensional perovskite CsCu2I3 host and constructed as a novel neutron/gamma detection scintillator via the Bridgman method. XRD and ICP-MS were carried out, and the results were discussed. The Li-doped CsCu2I3 crystal exhibits a main emission peak at 575 nm originating from strongly localized 1D exciton emission and a high photoluminescence quantum efficiency of 18.7%. The CsCu2I3:Li crystal has a light yield of 10 900 photons per MeV and an energy resolution of 11.5% under 137Cs irradiation. The figure-of-merit (FoM) of the CsCu2I3:Li crystal has been estimated (about 0.8) under 252Cf radiation source. The crystal has a potential application for dual gamma–neutron detection. [ABSTRACT FROM AUTHOR]

This paper presents a novel methodology for obtaining the free energy profiles and the self-diffusivity of gases in crystalline microporous materials. The proposed approach is based on X-ray diffraction performed in situ on powder rather than single crystal samples. As proof of concept, we derive the self-diffusion properties of CO2 and CH4 in a metal–organic framework, CAU-10-H. The free energy profiles and self-diffusivity values acquired experimentally using the proposed methodology match those obtained through molecular simulations. This XRD-based methodology can be used for the design of MOFs for membrane gas separation. [ABSTRACT FROM AUTHOR]

Recently, one of the uranium-based heavy fermion systems, UTe2, has attracted enormous attention because of its potential spin triplet superconductivity, whose superconducting properties are closely related to their compositions and states of crystallization. In this work, the crystal growth of UTe2 crystals was systematically studied by the CVT method. Various growth parameters, including growth temperature, the ratio of uranium to tellurium, and the type and amount of transport agents, were investigated. A lower growth temperature (710 °C) results in a smaller size of the UTe2 crystals, and too high of a growth temperature (1060 °C) makes the nucleation rate go out of control. The ingredients with higher tellurium content (U : Te = 2 : 5) lead to larger single crystals, while a shortage of tellurium (U : Te = 2 : 3) tends to form polycrystals with smaller sizes. Among the three types of transport agents we used, iodine forms larger crystal sizes than AgBr and TeBr4. When the amount of iodine is excess (2.45 mg cm−3), the crystal surface becomes rough, while not enough iodine makes the crystal thin and even bent. We have found that centimetre-sized high quality UTe2 single crystals can be grown by using an appropriate amount of iodine as the transport agent at 860 °C. The nucleation rate of UTe2 crystals is mainly determined by temperature and iodine partial pressure, while the growth rate is more sensitive to the tellurium partial pressure. The oxidation process of UTe2 crystals was observed and is also discussed in this paper. [ABSTRACT FROM AUTHOR]

Ascorbic acid (AA), which plays a crucial role in human biological systems, was fluorometrically detected by a 3D Cd(II)-containing metal--organic framework (MOF) sensor, named IITG-6 (IITG = Indian Institute of Technology Guwahati). Single crystals of IITG-6 were solvothermally synthesized using a 2-((pyridin-4ylmethyl)amino)terephthalic acid (H2BDC-NH-CH2-Py) linker. The MOF is thermally stable up to 320 °C and stable in aqueous medium. The guest free form of IITG-6 MOF (named IITG-6a) can detect AA turn-off fluorescence response in water. The sensor exhibited a short response time (<1 min) and nanomolar detection limit (31 nM). The AA sensing capability of IITG-6a was demonstrated in different fruit and vegetable samples like tomato, orange, Indian gooseberry and lemon. The MOF also showed its selective sensing ability towards AA in a human urine sample. Moreover, test paper strips containing the MOF powder were fabricated which are suitable for onsite AA detection. By combining DFT calculations with experimental techniques, the AA sensing mechanism has been investigated. [ABSTRACT FROM AUTHOR]

CrystEngCommrsc. li/ crystengcomm ISSN 1466- 8033 Volume 26 Number 17 7 May 2024 Pages 2221– 2334 PAPER Lingyan Xu et al. Pure organic TPB single crystal for direct X- ray detection [Extracted from the article]

High-quality seeding is the key to ensure the preparation of high-quality sapphire single crystals. The strength and direction of the melt flow control the crystal seeding shape and bubble movement and will directly affect the quality of crystal seeding. To improve the crystal seeding quality under complex convection, based on the lattice Boltzmann method, an optimization method of seed crystal rotation was proposed before crystal seeding, and the unsteady melt flow rate, internal temperature of the melt and crystal rotation speed were calculated and analyzed. The coupling relationship between the Grashof number and the Reynolds number is analyzed. The results show that the optimization method of crystal rotation can effectively restrain the convection of the melt and improve the temperature distribution on the surface of the melt. Compared with the multi-frame intercomparison visual inspection detection method and artificial seeding method, the method proposed in this paper is helpful to improve the quality of sapphire seeding. [ABSTRACT FROM AUTHOR]

In this paper, the growth and promotion of 2 inch AlN single crystals are carried out via the homogeneous physical vapor transport (PVT) method on AlN seeds. It is found that the large-size AlN crystal homo-PVT process is distinguished by the growth of prismatic grains in a macroscopic 3-dimensional mode, and overgrowth plays a key role in the merging of grains under a lateral overgrown c-plane surface. To realize efficient overgrowth, we study the control law of growth conditions through a combination of experiments and computational fluid dynamics (CFD) simulations, and clarify that the effect of overgrowth depends on growth rate and its matching relation with temperature and pressure. Our results show that overgrowth can obviously improve the coherence of c-plane orientations and crystal quality, which provides a foundation for quality promotion through iterative homo-PVT growth on large-size AlN seeds. [ABSTRACT FROM AUTHOR]

Advances and limitations in the field of growing large, high optical quality single crystals of AgGaS2 (AGS), AgGaGeS4 (AGGS), ZnGeP2 (ZGP), LiInS2 (LIS), LiGaS2 (LGS), LiInSe2 (LISe), LiGaSe2 (LGSe) and LiGaTe2 (LGT) compounds are considered in this contribution. With attendant good optical quality, all as-grown crystals of these compounds contain always some amount of native defects which adversely affect the optical and electrical properties. With the aim of overcoming this limitation, attention in this review is focused on concepts that provide a better insight into origins of non-stoichiometry and mechanism of native point defect occurrence. Among these concepts, preference is given to effective ways of determining the scale of the non-stoichiometry through the study of T–X and P–T diagrams, to promising techniques characterizing precisely phase purity, spatial chemical inhomogeneity, and amount of microstructural inclusions in grown crystals, and to measuring thermodynamic and thermochemical properties of the compounds. Utility of physicochemical characteristics for optimizing the growing process is considered. A combination of chemical information and physical properties of crystals is obligatory for clarifying the origins of defects. Attention is given to clarifying specificity of growing Li-containing crystals caused by high chemical activity of the Li component. With such content, this review paper presents status of current knowledge of non-stoichiometry and defects of crystals demanded in practice for non-linear optics. [ABSTRACT FROM AUTHOR]

The paper reports new results that compare the group of performance figures of merit of piezo-active 2–2-type composites based on [011]-poled domain-engineered (1 − x)Pb(Zn1/3Nb2/3)O3–xPbTiO3 single crystals, where the main crystallographic axes in the crystal layers are rotated to tailor effective electromechanical properties and related parameters. Examples of the orientation and volume-fraction dependences of the figures of merit are analysed for the first time for the system of 2–2 single crystal/polymer composites and 2–0–2 single crystal/corundum ceramic/polymer composites at x = 0.0475–0.09. The connections between the piezoelectric coefficients , energy-harvesting figures of merit and modified figures of merit (j = 1, 2 and 3) are highlighted during rotation of the main X and Y crystallographic axes around the Z axis of the crystal layers. A similar orientation behaviour of , and and their large anisotropy are studied at specific volume fractions of the single-crystal component and for a variety of microgeometric architectures of a corundum ceramic/polymer layer with 0–3 connectivity. Maxima of the longitudinal parameters , and at x = 0.0475–0.09 and constant volume fraction of the single-crystal component of the 2–2-type composites are observed in a relatively narrow orientation range. A new performance diagram is built to show regions of a large anisotropy of and in a 2–0–2 composite and, as a result of the large piezoelectric coefficients and figures of merit, the composites show significant potential in the field of piezoelectric energy-harvesting and sensor applications. [ABSTRACT FROM AUTHOR]

In this paper, we study the PL spectra of N-rich B-doped diamond single crystals grown in NiMnCo solvent, before and after HPHT (high pressure and high temperature) annealing. The PL peaks are observed under 325 nm, 488 nm and 532 nm excitation, respectively. The effects of boron impurity and HPHT annealing on optical centers in N-rich B-doped diamonds are discussed. Before HPHT annealing, as boron incorporation increases in the N-rich diamond, the intensity of the NV− center (627 nm) presents a trend of rising first and then falling. After HPHT annealing at 2.5 GPa and 2000 °C, PL spectra show complex luminescence systems. A series of lines related to Ni–N and Co–N complexes are observed at 602.2 nm, 729.4 nm, 748.8 nm and 542.7 nm in PL spectra under 532 nm and 488 nm excitation. The paramagnetic NE8 center with a ZPL at 793.6 nm appears in the PL spectrum of the N-rich diamond without a boron additive. In the 325 nm excitation PL spectrum of the N-rich B-doped diamond, we also observed the blue luminescence band known as "band-A". Boron incorporation significantly influences the PL intensity of Ni–N, Co–N and NV− related optical centers in diamonds. [ABSTRACT FROM AUTHOR]

For the hybrid organic–inorganic perovskites with the general formula of A2MIIX4 (A = methylammonium; MII = Mn, Cu and Co; X = Cl), the arrangement of metal ions and organic ligands leads to a delicate balance of space, spin and charge, which results in diverse properties. In this paper, we reported a group of hybrid organic–inorganic perovskite single crystals of (CH3NH3)2MnCl4, (CH3NH3)2CuCl4 and (CH3NH3)2CoCl4 grown by a simple solution evaporation method. Magnetic measurements show that all the single crystals display magnetic ordering at low temperature. Our results reveal a novel group of hybrid organic–inorganic magnetic perovskites. [ABSTRACT FROM AUTHOR]

The novel single component molecular ferroelectric single crystal of 1,3,5-trimethylnitrobenzene (TMNB) has been investigated in terms of its temperature dependent polar properties. Three phases have been found in the solid state of TMNB: phase I above 161 K, phase II (incommensurate) between 161 and 152 K and phase III below 152 K. The TMNB crystal structures were determined at 100 K (phase III, sp. gr. Pca21) and at 250 K (phase I, sp. gr. Pnma). Ferroelectricity of phase III along the c-axis has been confirmed by the pyroelectric measurements and observations of the hysteresis loops, revealing spontaneous polarization as small as ∼2 × 10−6 C m−2. The crystal is the first example of an origin of spontaneous polarization related to flexibility of the C–H⋯π hydrogen bonds (molecular joints). The TMNB molecules in the dimer can change the mutual orientation of the dipole moments without breaking the C–H⋯π bonds. In this paper, the mechanism of the phase transitions will be discussed, which is governed by the dynamics of the NO2 groups and the flexibility of the C–H⋯π dimer. [ABSTRACT FROM AUTHOR]

Studying the influence of oxygen on the growth and properties of diamond has research significance. In this paper, we created an oxygen-rich environment by adding Ni2O3 to the Fe–Ni–C system. Large single crystals of oxygen-containing diamond were successfully synthesized using the temperature gradient method (TGM) in a China-type large volume cubic high-pressure apparatus (CHPA) at 5.5–6.0 GPa and 1360–1600 °C. The results show that with the increase of the Ni2O3 content in the Fe–Ni–C system, the rate of diamond growth decreased while the conditions for diamond growth were enhanced. The morphology of the diamonds changed from {111}, {110} and {113} mixed faces to {111} dominant face. The IR results show that the presence of Ni2O3 increased the nitrogen content in diamonds from 237 ppm to 543 ppm. When 3.5 wt% Ni2O3 was added, A-centre nitrogen began to appear in the diamonds. The XPS results confirmed that oxygen successfully entered the diamond lattice in the form of C–O, C＝O, O–C＝O and N–O with a high concentration of Ni2O3 additives. Meanwhile, there were no obvious impurity inclusions and cracks in the diamond crystals. In addition, the Raman peak position of the diamond appeared to red shift, and the FWHM increased from 4.93 cm−1 to 5.52 cm−1. [ABSTRACT FROM AUTHOR]

A new benzothiadiazole-based MOF {[Zn(BIBT)(oba)]·DMA}n (JXUST-3, BIBT = 4,7-bi(1H-imidazol-1-yl)benzo-[2,1,3]thiadiazole and H2oba = 4,4′-oxybisbenzoate) has been solvothermally synthesized and characterized by single crystal X-ray diffraction, IR spectroscopy and TGA. The fluorescence studies suggest that JXUST-3 could simultaneously selectively sense trivalent metal ions including Al3+, Cr3+ and Fe3+ by a turn-off effect, and the detection limits are 0.055, 0.049 and 0.056 μM, respectively. Moreover, JXUST-3 exhibits relatively good thermal and chemical stabilities and reusability. The fluorescent test paper also displayed an obvious turn-off effect, indicating that JXUST-3 can be used as a potential multi-response fluorescent probe. The possible quenching mechanisms of JXUST-3 for Al3+ and Fe3+ were competitive energy absorption, and for Cr3+ ions, they were competitive energy absorption and weak interactions between Cr3+ and the framework. Therefore, JXUST-3 could be viewed as a transition metal MOF fluorescence sensor for Al3+, Cr3+ and Fe3+ by the turn-off effect, simultaneously. [ABSTRACT FROM AUTHOR]

A specific number of structures described in this paper with adamantane and memantine fragments have been synthesised and characterised. Their single crystals have been grown and their crystal structures have been determined. XPac analysis has shown that there are four sets of isostructural crystals based on adamantane/memantine-specific hydrogen bond patterns and packing of bulky substituents. The use of packing density analysis, QTAIMC and Hirshfeld surface analyses has allowed the elucidation of the influence of the nature and position of functional groups and molecular arrangement on the strength of non-covalent interactions in crystals and overall packing efficiency. The nature and size of a fragment in the para-position of the phenyl ring have been found to have the highest influence on the packing architecture. [ABSTRACT FROM AUTHOR]

It is difficult to control the stability of the 4H polytype in the growth of SiC single crystals by the PVT method. When the crucible was immovable, it was found that the temperature and the temperature gradient of the growth interface gradually increased and were almost unchanged with the crystal growth by the simulation. This resulted in the segregation of the gas composition and a variable Si/C ratio of the growth interface, due to which polytype inclusions and defects were easily formed. In this paper, we proposed a new method for stabilizing the 4H polytype of the SiC crystals by controlling the temperature field of the growth interface and gradually moving up the graphite crucible during crystal growth. The simulation results showed that the method could simultaneously reduce the range of the temperature rise and drop the temperature gradient at the growth interface. Thus, the gas phase composition was stable during the growth process, which will be useful for the stability of the 4H polytype. Finally, 4 inch SiC single crystals with 4H polytype stability and low defects were successfully obtained though this new method. Also, the quality of the as-grown SiC crystals was characterized by X-ray diffraction, Raman spectroscopy and Candela optical surface analysis. The results show that the method of slowly moving up the crucible during crystal growth is very effective in controlling the 4H polytype and improving the quality of SiC single crystals. [ABSTRACT FROM AUTHOR]

In this paper, a series of D–π–A type benzo[e]indolium salts with highly efficient nonlinear optical performance has been synthesized. Out of the three new benzo[e]indolium salts, (E)-2-(2-hydroxy-3-methoxystyryl)-1,1,3-trimethyl-1H-benzo[e]indol-3-ium iodide (HMTB-1) and (E)-2-(2-hydroxy-4-methoxystyryl)-1,1,3-trimethyl-1H-benzo[e]indol-3-ium iodide (HMTB-2) possess SHG properties, and their maximum powder second harmonic generation (SHG) efficiency is around 0.6 times that of DAST (4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate) at a non-resonant wavelength of λ = 1570 nm. Single crystals of the two noncentrosymmetric salts were successfully grown by using a slow cooling method, and we were able to obtain very large bulk single crystals, about 17 mm × 9 mm × 3 mm, of HMTB-2. X-ray crystallographic analysis indicated that both of the new salts belong to the monoclinic space group Cc (point group m, Z = 4). HMTB-1 forms a noncentrosymmetric phase with methanol through hydrogen bonding. [ABSTRACT FROM AUTHOR]

A model was proposed for modeling the non-equilibrium crystal growth of single crystals (Y. D. Shu, Y. Li, Y. Zhang, J. J. Liu and X. Z. Wang, CrystEngComm, 2018, 20, 5143–5153). It describes mathematically and digitally the non-equilibrium growth behavior of single crystals using multi-component transfer rate models, as well as considering multi-component phase equilibria, adsorption, orientation and crystallization of individual molecules on crystal faces. In this paper, the model for single crystal growth is extended to modeling a population of crystals in a crystallizer by incorporating it into morphological population balance equations. The resulting modeling approach, i.e. the multi-stage multi-component transfer rate morphological population balance equation (M3PBE) model, is able to predict the spatial and temporal distribution of multi-components inside crystals during the course of crystallization as well as the multi-component composition of the product crystals. The new modeling approach is introduced by reference to a case study of NaNO3 batch cooling crystallization in water. [ABSTRACT FROM AUTHOR]

First principles calculations of the α-quartz phase of Si1−xSnxO2 predict great benefits of the substitution of Si by Sn with the d11 piezoelectric constant (5.72 pC N−1) for Si0.8Sn0.2O2, which is predicted to be twice that of quartz (2.85 pC N−1). Furthermore, the value of the d11 piezoelectric constant increases four times in the case of substitution with tin in comparison with that for germanium. The first Sn-substituted α-quartz single crystals have been grown under hydrothermal conditions, but the degree of substitution is still very low (xmax = 0.001). The analyses of additional compounds recovered after growth runs indicate that Sn crystallizes in a six-fold coordination with silicon by forming a mixed Si/Sn oxide in the autoclave, which may explain the low degree of substitution in the α-quartz single crystals. A new compound with the formula Na2Si4SnO9(OH)4 is identified, and the structure is determined. This paper predicts high performance of the Sn-substituted single quartz crystals. Crystal growth experiments show that Sn substitution is possible in the structure of quartz-type by using a crystal growth process favoring the formation of four-fold coordinated Sn species [SnO4] in the solution for obtaining a high Sn ratio in the quartz-crystals. [ABSTRACT FROM AUTHOR]

In this paper, systematic halogen doping of CH3NH3PbI3−xBrx and CH3NH3PbBr3−yCly bulk single crystals that were grown in mixed organic solvents via the ITC (inverse temperature crystallization) method was performed. X-ray diffraction measurement results show that the lattice constants of CH3NH3PbI3−xBrx and CH3NH3PbBr3−yCly crystals change linearly with the x(y) values. For the CH3NH3PbI3−xBrx crystals, cubic to tetragonal phase transformation was observed where the iodine content reaches a certain level. The comparison of UV-vis-NIR absorption and PL spectra of CH3NH3PbI3−xBrx and CH3NH3PbBr3−yCly crystals shows that their absorption coefficients are contributed by direct and indirect bandgap transitions. Three kinds of mechanisms were involved in their radiative recombination, including direct emission, indirect emission and direct–indirect coexisting emission. The CH3NH3PbI3−xBrx (x = 1.64, 2.39, 2.81, 2.9) crystals were considered to be indirect band gap materials, since their band edges can be divided into two regions by a turning point. TG analysis shows that the beginning decomposition temperature of CH3NH3PbI3−xBrx and CH3NH3PbBr3−yCly crystals decreases with increasing x(y) values. Research on CH3NH3PbI3−xBrx and CH3NH3PbBr3−yCly single crystals would be helpful to reveal the inherent properties of perovskite materials. [ABSTRACT FROM AUTHOR]

The synthesis of aqueous CdTe/CdS quantum dots (QDs) embedded in potassium dihydrogen phosphate KH2PO4 (KDP) is demonstrated. CdTe/CdS QDs were synthesized in water solution, followed with incorporation into an inorganic salt by the method of slow evaporation of water under ambient conditions. The resulting KDP:CdTe/CdS composites are new types of solid-state conversion materials with emission colors covering green to red spectral regions. In this paper, we report the optical and electrical properties of KDP:CdTe/CdS composites. The composites exhibit anisotropic photoluminescence properties, and due to the protection of the tight matrix, good thermal and chemical stability. [ABSTRACT FROM AUTHOR]

The physical vapor transport growth of aluminium nitride (AlN) layers was performed in one process with the evaporation of silicon carbide (SiC) substrates. In this paper, we show that the rate of SiC evaporation is slow in a narrow process window for AlN growth but increases in the presence of AlN vapor. The properties of the substrates influence the evaporation process; therefore an investigation is done to understand this phenomenon. We first describe the evaporation behavior of a SiC substrate depending on its size, thickness, structure and polarity. Then we demonstrate the surface morphology and structural quality of the AlN layers grown on C-polar SiC. In the case of a step-flow growth, our method allows us to obtain thin freestanding layers with moderate dislocation densities and rocking curve widths comparable to those of bulk crystals. [ABSTRACT FROM AUTHOR]

Ammonium dihydrogen phosphate (NH4HPO4, ADP) crystal can be used to generate second, third and fourth harmonics. In this paper, the growth characteristics of ADP and the differences between the growth solubility and structures of potassium dihydrogen phosphate (KDP) and ADP crystal are discussed in detail. Ex situ atomic force microscopy (AFM) was applied to explore the growth morphology of ADP crystal at different supersaturation values. A series of ADP crystals were grown, and the transmission spectra of ADP crystals across the whole transmission region were measured. Laser-induced damage threshold (LDT) was measured, and was found to be higher than the average value of LDT of KDP and 70% deuterated DKDP crystals. [ABSTRACT FROM AUTHOR]

The effects of crystallization on the formation of geochemical, biological, and synthetic materials have been motivating decades of research into crystal nucleation and growth processes. The development of crystal growth theories and models can deepen the understanding of physicochemical interactions during the crystal growth process, which facilitates the designing of crystallization approaches in material production. The chemical bonding theory of single crystal growth emphasizes the dominant role of dynamic chemical bonding mechanisms at the growing interfaces. In this paper, we highlight the chemical bonding theory of single crystal growth from the chemical reaction viewpoint, by focusing on the atomic level of the growing interface between the liquid and crystal phases. Using ZnO, CeO2, MnO2 and Y3Al5O12 as examples, we review some typical applications of the chemical bonding theory of single crystal growth in calculating crystal habits, evaluating crystal properties, and guiding practical single crystal growth. Microscopically speaking, the essence of crystal growth and design is to create ideal chemical bonding architectures at both the crystal surface and the growing interface via both thermodynamic and kinetic strategies. [ABSTRACT FROM AUTHOR]

Multi-component crystals – salts, co-crystals, or solvates – are usually designed based on the analysis of the complementarity of functional groups and intermolecular interactions of the components. However, no crystal design can do without a practical method of crystal growth. Not all compounds that should be expected to exist based on the “synthon approach” can be prepared in real experiments. This paper aims to illustrate that, in addition to the synthon approach, it is equally important to take into account phase diagrams when searching for practical methods of crystallising multi-component crystals, either as single crystals or as fine particles. Here, we describe the crystallization of a bis(paracetamol) pyridine solvate from a glass-like metastable phase produced by quench-freezing of a paracetamol–pyridine solution with subsequent low-temperature annealing. These procedures must be carried out strictly within the boundaries of the two-phase region “solid solvate + liquor”, which was found only as a result of modelling the phase diagram. The crystal structure was solved by single-crystal X-ray diffraction and compared with co-crystals of paracetamol found in the Cambridge Structural Database. The structure-forming role of the intermolecular interactions and their characteristics were studied by variable-temperature experiments over the range of 100–275 K. This was compared with the structures of pure paracetamol polymorphs and other solvates and co-crystals at ambient and non-ambient conditions. [ABSTRACT FROM AUTHOR]

In this paper, BiCuSeO single crystals are successfully grown by a flux method at different growth temperatures (690 °C, 730 °C and 775 °C). The crystal surface morphology, microstructure, chemical composition and electrical properties are systematically characterized. By changing the growth temperature, the growth mechanism evolution, from dislocation-driven spiral growth mode to two-dimensional layer-by-layer mode, is observed due to the different growth supersaturations. Simultaneously, the temperature-dependent resistance confirms the electrical property changes from semiconductor to metal. Chemical analysis proves that BiCuSeO crystals grown at higher temperatures (730 °C and 775 °C) are slightly non-stoichiometric. The present results demonstrate the possibility of modulating the crystal morphology and electrical properties of BiCuSeO by controlling the supersaturation. This method may be applicable to similar compounds (BiCuOCh (Ch = S, Te)). [ABSTRACT FROM AUTHOR]

This paper reports the preparation and X-ray single crystal structures of five organic-inorganic hybrid compounds with 3D framework, (Cu2.5(bimpy)2(H2O)2][Ln(H2O)3(α-SiW11O39)]⋅ xH 2O [Ln = EuIII and x = 3.5 for (1), Ln = SmIII and x = 2.5 for (2), Ln = HoIII and x =3.5 for(3), Ln = Y and x = 3.5 for (4), Ln = CeIII and x =3 for(5)] (bimpy = 3,5-bis(1-imidazolyl)pyridine). Compounds 1-5 are isostructural, showing a 3D framework featured by {-SiW11-Ln-SiW11-} inorganic chains and {Cu/bimpy} metal-organic ribbons stemmed from Cu ions and bimpy ligands. The adjacent {Cu/bimpy} ribbons are connected by two anti- parallel {-SiW11-Eu-SiW11-} chains to create a 2D layer structure, which is extended to a (3,4,4,4,6)- connected 3D framework with (4.7²)(4.6.7³.8)(4².5³ .7)(4².7².9²)(4².5².67.8³.10) topology through the Cu-O covalent bonds. The magnetic and electrochemical properties of compounds 1 and 2 have been studied. [ABSTRACT FROM AUTHOR]

Six novel Cd(II) complexes, Cd(bpmi)2Cl2 (1), [Cd(bpmi)2(NO3)2(H2O)]n (2), [Cd2(bpmi)2Cl2(N3)2(CH3OH)2]n (3), [Cd(bpmi)Cl2]n (4), [Cd(bpmi)(SCN)2]n (5) and [Cd(bpmi)(N3)2]n (6), are synthesized by the reaction of different Cd(II) salts with an asymmetric multidentate ligand 1-(benzotriazole-1-methyl)-2-propylimidazole (bpmi). X-ray single-crystal analyses reveal that these complexes show rich structural chemistry ranging from mononuclear (1), one-dimensional (2 and 3), two-dimensional (4 and 5) to three-dimensional (6) structures. These complexes share common features such as they all contain inorganic SBUs and have a high degree of dependence on the corresponding counter anions. In this paper, the fine regulation of counter anions has been discussed in detail. Furthermore, these complexes have been investigated by solid-state UV-vis spectra, thermogravimetric analyses and fluorescence spectra. [ABSTRACT FROM AUTHOR]

In this paper, diamond single crystals co-doped with H and B were successfully synthesized under a fixed pressure of 6.0 GPa and temperature ranging from 1560 to 1600 K. In the synthesized diamond, hydrogen was found to be mainly incorporated as sp³ CH2, which had been detected by its characteristic stretching absorptions at 2920 cm-1 and 2850 cm-1 from the Fourier transform infrared spectra. Raman measurements indicated that the diamonds co-doped with B and H had a more compatible lattice structure than B-doped diamond. Hall effect measurements indicated that the co-doped diamonds showed p-type semiconductor behavior. Besides, the Hall mobility was nearly equivalent between B-doped and co-doped diamond crystals, while the concentrations of the carrier and conductivity of the co-doped diamonds were higher than that of the B-doped diamond crystals. [ABSTRACT FROM AUTHOR]

In this paper, hexagonal bipyramids and X- and polycrystal-shaped twins of cholic acid are acquired through the acidic hydrolysis of its ester hydrogel. The growth mechanism is proposed on the basis of the hydrophobic swallowtail-shaped tetramers found in the single-crystal structure. [ABSTRACT FROM AUTHOR]