In this paper, a tetragonal LiY(MoO 4 ) 2 single crystal with a bulk size of 23 × 20 × 18 mm 3 was successfully grown for the first time by a top-seeded solution growth (TSSG) method. The full-width ...at half maximum of the (100) and (001) crystal wafers reached 27 and 43 arcsec, respectively. The transmission spectra show that the LiY(MoO 4 ) 2 crystal possesses a wide transparency window in the range of 0.344 to 5.493 μm. The thermal property studies indicate that the LiY(MoO 4 ) 2 crystal has a relatively large specific heat of 0.735 J/(g K). The thermal conductivity coefficients were determined to be 0.935 W m −1 K −1 and 1.047 W m −1 K −1 along the a and c axes at 30 °C, respectively. It is worth noting that the crystal exhibits a comparatively small thermal expansion anisotropy of 1.35, which indicates a relatively large laser damage threshold.
The rapid development of kilowatt-level lasers is in urgent need of excellent magneto-optical materials for Faraday isolators. In this work, a new component Tb
3
Al
2
Ga
3
O
12
crystal was designed ...to meet applications in high-power lasers. A high-quality single crystal has been successfully obtained by the Czochralski technique. The Tb
3
Al
2
Ga
3
O
12
crystal is verified to have high crystallinity with a small full width at half maximum (FWHM) of 43.2′′ and exhibits excellent uniformity, especially enhanced magneto-optical properties, exceeding ∼7-15% that of the traditional TGG crystal. These excellent attributes suggest that the Tb
3
Al
2
Ga
3
O
12
crystal can be a promising candidate for Faraday isolators.
A new component Tb
3
Al
2
Ga
3
O
12
magneto-optical crystal was obtained successfully for the first time; it exhibits an excellent transmittance of over 80% and a superior magneto-optical effect compared to the traditional TGG crystal.
In this letter, a novel acousto-optical (AO) Q-switch is designed by using <inline-formula> <tex-math notation="LaTeX">\alpha </tex-math></inline-formula>-BaTeMo<inline-formula> <tex-math ...notation="LaTeX">_{\mathbf {2}}~\text{O}_{\mathbf {9}} </tex-math></inline-formula> crystal grown by the flux method. The acousto-optical modulator (AOM) exhibits a high polarization extinction ratio of 65 dB with a rise time of 32.8 ns and insertion loss of 3.66 dB. An actively Q-switched ytterbium doped all fiber laser at 1035 nm is successfully realized by using the prepared AOM. Under a pump power of 404.9 mW, a maximum output power of 1.66 W is obtained with pulse width of 167 ns at the modulation rate of 10 kHz. The results show that the <inline-formula> <tex-math notation="LaTeX">\alpha </tex-math></inline-formula>-BaTeMo<inline-formula> <tex-math notation="LaTeX">_{\mathbf {2}}~\text{O}_{\mathbf {9}} </tex-math></inline-formula> AOM is a potential Q-switch for all fiber lasers.
Germanium phosphide (GeP), a typical 2D group IV–V semiconductor, has attracted significant attention due to the advantages of higher thermodynamic stability than black phosphorus (BP), widely ...tunable bandgap, high carrier mobility, and in‐plane anisotropy. However, its photonic and optoelectronic properties have not been extensively explored so far. Herein, large size and high‐quality GeP single bulk crystal is successfully grown by flux method and stripped into 2D nanosheets with liquid phase exfoliation (LPE) and spin‐coating methods. The broad‐band photonic and optoelectronic properties of 2D GeP nanosheets are systematically investigated. First principles calculations are performed to verify its widely tunable bandgap from 0.43 eV for bulk to 1.58 eV for monolayer. The ultrafast carrier dynamic and non‐linear optical responses are investigated by non‐degenerated pump‐probe and open‐aperture Z‐scan methods, and the results indicate that 2D GeP nanosheets can present excellent broad‐band saturable absorption properties. Furthermore, the 2D GeP nanosheets‐based broad‐band saturable absorbers (SAs) and photodetectors are demonstrated. The results indicate that 2D GeP nanosheets can be used as excellent broad‐band optical modulators and detectors, which will arouse a considerable interest in exploring novel group IV–V 2D materials for broad‐band photonic and optoelectronic applications.
The broad‐band and strong light–matter interaction, air stability, and ultrafast carrier dynamics process of 2D GeP semiconductor are systematically investigated. Broad‐band optical switch and photodetector based on high‐quality 2D GeP have been successfully fabricated, indicating its potential applications in photonic and optoelectronic devices. This work will impel researchers to explore novel outstanding photonic and photo‐electronic materials in IV–V group semiconductors.
A kind of dislocation occurring on the surface of the β-Ga2O3 (001) substrate and line-shaped defects caused by these dislocations in the epitaxial layer are responsible for the reverse leakage ...current and breakdown of power devices. Therefore, this type of dislocation is very disadvantageous for the performance of power devices, and the β-Ga2O3 (011) plane can effectively reduce or even completely avoid the influence of this defect due to its parallel relationship with this kind of dislocation. However, there is still a lack of systematic evaluation of the performance of this crystal plane. In order to determine whether the (011) plane is a potential substrate orientation, a series of (011)-oriented substrates were processed from β-Ga2O3 bulk crystals grown by the edge-defined film-fed growth (EFG) method to pursue further research. The high quality of the substrate was proved from the full width at half maximum (FWHM) of 66.79 arcsec in the X-ray rocking curve, and the wet etching method was used to study the dislocation distribution. The low-dislocation-density characteristic of the (011) plane was confirmed and the quadrilateral etch pit was observed by atomic force microscopy (AFM), which indicated that these etch pits were caused by other defects. In addition, the photoelectric properties and the element composition of the (011) plane were evaluated through Raman spectroscopy, optical transmittance spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results indicated that the (011) plane not only had a low-dislocation-density characteristic but also showed excellent photoelectric properties. At the same time, benefiting from the absence of the kind of dislocation mentioned above, the β-Ga2O3 (011) plane could be a potential substrate orientation for a high-quality epitaxial layer.
Based on the disadvantages of crystal processing and device fabrications of 3D halide perovskites, there is a need to introduce aromatic ammonium into CH
3
NH
3
PbI
3
to address these concerns. ...Herein, we report the controllable growth of layered perovskite (C
6
H
5
CH
2
CH
2
NH
3
)
2
(CH
3
NH
3
)
n
−1
Pb
n
I
3
n
+1
(
n
= 1-3) single crystals realised by controlling the proper molar ratio of reactants in the ambient atmosphere. Interestingly, two polymorphs of (C
6
H
5
CH
2
CH
2
NH
3
)
2
PbI
4
single crystals coexisted, and their phase transformation were achieved by different strategies. Moreover, the crystal structure determinations, band gap, optical properties, and thermal stability of the (C
6
H
5
CH
2
CH
2
NH
3
)
2
(CH
3
NH
3
)
n
−1
Pb
n
I
3
n
+1
(
n
= 1-3) single crystals were studied in detail. The (C
6
H
5
CH
2
CH
2
NH
3
)
2
(CH
3
NH
3
)
n
−1
Pb
n
I
3
n
+1
(
n
< 3) single crystals with quantum well structures exhibited strong photoluminescent properties. These intriguing features may lay the foundation for optoelectronic applications of the layered perovskite materials.
Phase transformation processes of (C
6
H
5
CH
2
CH
2
NH
3
)
2
PbI
4
single crystals by different strategies were achieved.
The lateral device structure for perovskite solar cells (PSCs) has garnered significant attention, primarily due to its elimination of the need for expensive transparent electrodes. However, the ...performance of lateral devices, which are more sensitive to crystal quality and charge carrier transport bottlenecks, has lagged far behind the predominant vertical PSCs. Herein, by modulating the crystal nucleation and growth processes of thin FA0.75MA0.25PbI3 (FA = formamidinium; and MA = methylammonium) single crystals, crystal quality and carrier transport are improved, resulting in a power conversion efficiency (PCE) of 12.64%, a record for lateral PSCs. Investigation of the device's stability reveals that iodide ion migration is suppressed due to a reduction in the iodide vacancy concentration combined with weak interface iodide ion migration. It is shown that the latter effect is a result of the perpendicular direction of the ion migration and the electric field in the lateral PSCs. Consequently, these lateral single‐crystal PSCs display remarkable operational stability, retaining 100% of their initial PCE after 1200 h of steady‐state output at the maximum power point voltage (Vmpp) under 1 sun illumination. This work highlights the advantages of lateral single‐crystal devices and their potential to address key ion migration issues of PSCs.
The interface iodide ions migration is weak in lateral perovskite solar cells due to the nearly perpendicular direction of electric field and ion migration. Besides, the bulk iodide ions migration can mitigate through optimizing the crystal quality. The combination of mitigated interface and bulk iodide ions migration leads to lateral perovskite solar cells with superior operational stability.
Copper based coordination materials possess the ability to change their physico-chemical properties in response to external stimuli. Recent studies related to Cu(
i
) complexes have revealed the ...external stimuli triggered luminescence variations such as thermochromism, vapochromism, and mechanochromism, during which the underlying mechanism was attributed to the appearance of various polymorphs. However about the structural isomerization between the structural isomers proceeding on a concrete crystal, researchers still lack a deep understanding of the morphology evolution in a stimulus-based isomerization process. In this study, we dug into the structural isomerization process in the representative copper iodide coordination crystals of CuI(py)
n
(py = pyridine) and CuI(py)
4
. Under multiple stimuli such as heat, mechanical force and solvent annealing, the "chain" cluster of CuI(py)
n
was found to convert into the "cubane" cluster of CuI(py)
4
, exhibiting high contrast photoluminescence from blue to yellow. Systematic comparative studies and detailed analysis of the interface evolution during isomerization in single crystals reveal an underlying conversion mechanism of the dissociation-reorganization process. Such a deep understanding of the structural isomerization would facilitate real applications of multi-stimuli responsive Cu(
i
) complexes.
Structural isomerization of copper iodide-pyridine crystals under multiple stimuli was monitored, revealing a three-step dissociation-reorganization mechanism.
A single crystal of LiNa5Mo9O30 of 52 × 44 × 8 mm3 was successfully grown using the top-seed solution growth method. The full width at half maximum of the high-resolution X-ray diffraction rocking ...curve for the (100) plane is 17′′. The LiNa5Mo9O30 single crystal can transmit well from 0.31–5.35 μm. It was easily processed with a moderate hardness of 5.2. The specific heat curve increases slowly without an inflection point. The thermal expansion coefficients were measured to be αc > αa > αb, and the structure–property relationship was discussed in detail. It exhibits good thermal conductivity with κa = 2.67 W m−1 K−1, κb = 3.61 W m−1 K−1, and κc = 3.22 W m−1 K−1, respectively. As a molybdenum crystal, the spontaneous Raman spectra along the a-axis with different Raman configurations were characterized. There is a strong Raman shift at 946.6 cm−1, which can be used for Raman laser applications. Our results show that the LiNa5Mo9O30 single crystal is not only a second order nonlinear optical crystal but also an excellent candidate for stimulated Raman scattering.
Single-crystal-to-single-crystal (SCSC) phase transition is an ideal model to study the structural correlation between the polymorphs at the molecular level. In this regard, a transition process with ...concomitant emission color change is in favor of direct visualization by fluorescence microscope. Here we report an SCSC transition on the luminescent single crystal of large conjugated molecules, which is accompanied by a drastic luminescence color change from red to orange upon heating. The transition process was clearly recorded under both fluorescence and polarized light. Combining with crystallographic analysis, the results indicate that the existence of molecular layers and the oriented motion of the interface between the daughter and the parent phase preserved the integrity of the single crystal, despite of remarkable changes of both conformational and supramolecular structure. Thus, the transition is rationalized to proceed by a nucleation-and-growth mechanism but not a martensitic one. This work on one hand delivers intuitive cognition about the polymorph-dependent optical properties and the mechanism of the phase transition between the polymorphs and, on the other hand, also proved the paramount importance of direct microscopy observation about the actual transition process.
