Crystals

Research

9 pages, 1579 KiB

Open AccessArticle

Synthesis of g-C₃N₄ from Various Precursors for Photocatalytic H₂ Evolution under the Visible Light

by Pengfei Xia, Guojing Li, Xiaowei Li, Shuhua Yuan, Kang Wang, Dingwang Huang, Yuanpeng Ji, Yunfa Dong, Xiaoqiang Wu, Linyu Zhu, Weidong He and Liang Qiao

Crystals 2022, 12(12), 1719; https://doi.org/10.3390/cryst12121719 - 26 Nov 2022

Cited by 25 | Viewed by 4274

Abstract

Graphitic carbon nitride (g-C₃N₄) fabricated from different precursors exhibits unique microstructures and photocatalytic performance under visible light. Herein, we synthesized five different microstructures of g-C₃N₄ by the thermal poly condensation method using guanidine hydrochloride, melamine, urea, [...] Read more.

Graphitic carbon nitride (g-C₃N₄) fabricated from different precursors exhibits unique microstructures and photocatalytic performance under visible light. Herein, we synthesized five different microstructures of g-C₃N₄ by the thermal poly condensation method using guanidine hydrochloride, melamine, urea, dicyandiamide and thiourea as the precursors. The results indicated that g-C₃N₄ prepared from urea precursor (UCN) has a nanostructure, porous layered structure, large specific surface area, and high separation efficiency of photo generated hole-electron pairs, which showed the best photocatalytic activity among all of the as-prepared samples. As for the lowest cost among the above five precursors, urea is an ideal candidate material for preparing g-C₃N₄ photocatalyst for a huge potential of wide industrial applications. In addition, Pt or Ni were used as the co-catalyst and loaded onto the g-C₃N₄ surface for photocatalytic hydrogen production. In comparison with noble metal Pt co-catalyst, Ni co-catalyst is inexpensive and has a significant effect o enhancing the photocatalytic activity under visible light. Therefore, Ni exhibits a considerable prospect to replace noble metal co-catalysts in the photocatalytic reactions. Full article

(This article belongs to the Special Issue Advances in Optoelectric Functional Crystalline Materials)

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12 pages, 2881 KiB

Open AccessArticle

Enhanced Photocatalytic Activities for Degradation of Dyes and Drugs by Crystalline Bismuth Ferrite-Modified Graphene Hybrid Aerogel

by Yan Zhao, Minghui Xu, Yuanpeng Ji, Yunfa Dong, Guangjian Xing, Pengfei Xia, Xiaowei Li, Weidong He and Liang Qiao

Crystals 2022, 12(11), 1604; https://doi.org/10.3390/cryst12111604 - 10 Nov 2022

Cited by 8 | Viewed by 2231

Abstract

Industrial wastewater contains diverse toxic dyes and drugs, which pollute the environment and poison creatures. Utilizing photocatalysts has been accepted to be an effective method to degrade water pollutions using solar light. Crystalline bismuth ferrite (Bi₂Fe₄O₉) with [...] Read more.

Industrial wastewater contains diverse toxic dyes and drugs, which pollute the environment and poison creatures. Utilizing photocatalysts has been accepted to be an effective method to degrade water pollutions using solar light. Crystalline bismuth ferrite (Bi₂Fe₄O₉) with a band gap of 1.9–2.0 eV is expected to be one of the most promising candidates for photocatalysts in the visible light region. Amorphous graphene is also a promising candidate as a photocatalyst owing to its excellent electronic and optical properties. Herein, a composite of Bi₂Fe₄O₉/graphene aerogels (GAs) was prepared with a two-step hydrothermal method. The prepared Bi₂Fe₄O₉ powders were confirmed to be successfully doped into GAs and evenly dispersed between graphene sheets. The Bi₂Fe₄O₉/GA composite was utilized to perform photodegradation for organic dyes and antibiotic drugs under visible light irradiation, yielding efficiencies of 90.22%, 92.3%, 71.8% and 78.58% within 330 min for methyl orange, methylene blue, Rhodamine B and tetracycline hydrochloride, respectively. Such distinct photocatalytic activities overwhelmed the pure Bi₂Fe₄O₉ powders of 14.10%, 22.19%, 13.98% and 48.08%, respectively. Additionally, the composite produced a degradation rate constant of 0.00623 min⁻¹ for methylene blue, which is significantly faster than that of 0.00073 min⁻¹ obtained by the pure powder. These results provide an innovative strategy for designing 3D visible-light-responsive photocatalysts combined with graphene aerogel for water purification. Full article

(This article belongs to the Special Issue Advances in Optoelectric Functional Crystalline Materials)

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10 pages, 3506 KiB

Open AccessArticle

Growth and Spectral Properties of Er³⁺ and Yb³⁺ Co-Doped Bismuth Silicate Single Crystal

by Yan Zhang, Shucheng Hu, Tian Tian, Xuefeng Xiao, Yuanzhi Chen, Yan Zhang and Jiayue Xu

Crystals 2022, 12(11), 1532; https://doi.org/10.3390/cryst12111532 - 27 Oct 2022

Cited by 10 | Viewed by 1843

Abstract

Rare-earth-doped bismuth silicate (Bi₄Si₃O₁₂, BSO) crystal is a multifunctional material for scintillation, LED, and laser applications. In the present study, Er³⁺ and Yb³⁺ ions co-doped bismuth silicate crystals were grown by a modified vertical Bridgman [...] Read more.

Rare-earth-doped bismuth silicate (Bi₄Si₃O₁₂, BSO) crystal is a multifunctional material for scintillation, LED, and laser applications. In the present study, Er³⁺ and Yb³⁺ ions co-doped bismuth silicate crystals were grown by a modified vertical Bridgman method, and their spectral properties were investigated for the first time. Transparent Er/Yb: BSO single crystal up to Φ 25 mm × 30 mm was obtained. The segregation coefficient of the Er/Yb: BSO crystal was measured to be 0.96 for Er³⁺ ions and 0.91 for Yb³⁺ ions. Absorption and fluorescence spectra had been recorded in the range of 200–1700 nm. The absorption cross section was calculated to be 6.96 × 10⁻²⁰ cm² at 976 nm with the full width at half maximum (FWHM) of 8 nm, and the emission cross section was 0.9771 × 10⁻²⁰ cm² at 1543 nm with FWHM of 16 nm. The fluorescence decay curve was measured at 976 nm excitation. By linear fitting, the fluorescence lifetime of the upper ⁴I_13/2 level of Er³⁺ was 8.464 ms at room temperature. Compared with Er³⁺ ion-doped bismuth silicate crystal (Er: BSO), the Er/Yb: BSO crystal has a wider FWHM and larger absorption cross section. The results indicate that the Er/Yb: BSO crystal is a potential lasing crystal. Full article

(This article belongs to the Special Issue Advances in Optoelectric Functional Crystalline Materials)

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11 pages, 1937 KiB

Open AccessArticle

A Promising Crystalline KCl: Electrolyte Material for Studying the Electrochemical Properties of Cerium on Liquid Indium Electrodes

by Minghui Xu, Yan Zhao, Yuanpeng Ji, Yunfa Dong, Huaqian Leng, Xiaowei Li, Weidong He and Liang Qiao

Crystals 2022, 12(11), 1509; https://doi.org/10.3390/cryst12111509 - 25 Oct 2022

Cited by 5 | Viewed by 2205

Abstract

Potassium chloride crystals are good conductors in the UV to mid-infrared broadband and can be widely used as materials for high-power CO₂ lasers. However, the most important use of potassium chloride crystals has been overlooked; their stable chemistry and wide electrochemical window [...] Read more.

Potassium chloride crystals are good conductors in the UV to mid-infrared broadband and can be widely used as materials for high-power CO₂ lasers. However, the most important use of potassium chloride crystals has been overlooked; their stable chemistry and wide electrochemical window allow them to form molten eutectic salts with other chlorides for the dry reprocessing of spent fuel. The aim of this work is to investigate the electrochemical properties of the actinide substitute cerium metal on liquid indium media in order to provide basic data for further realization of lanthanides (Ln)/actinides (An) separation. In this paper, we investigated the electrochemical behavior of 3LiCl-2KCl-CeCl₃ melt at liquid metal media indium (In) electrode using various transient electrochemical analysis methods, such as cyclic voltammetry, square wave voltammetry and open circuit potential technique. The quasi-equilibrium potentials of Ce³⁺ at different temperatures on the liquid metal In electrode were determined. On the redox process, the reaction kinetics of the oxidation–reduction process in the 3LiCl-2KCl-CeCl₃ system is studied. It was determined that the reduction of Ce³⁺ at the liquid metal In electrode is an irreversible single-step process with three electron transfers. The relationship between the diffusion coefficient and the reduction process of Ce³⁺ ions on liquid metal indium electrodes at different temperatures was determined. The expression for the diffusion coefficient and temperature of Ce³⁺ at the liquid metal indium electrode is: lnD = 1.43 − 7974.69/T. Full article

(This article belongs to the Special Issue Advances in Optoelectric Functional Crystalline Materials)

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12 pages, 3030 KiB

Open AccessArticle

Effect of Cr Doping on the Structural, Optical and Dielectric Properties of MoO₃ Microrods Synthesized by Sol-Gel Auto Combustion Method

by Abid Zaman, Neeraj Kumar Shukla, Asad Ali, Aiyeshah Alhodaib, Vineet Tirth, Zahraa Hashim Kareem, Abdullah Hasan Jabbar, Muhammad Mushtaq, Mujahid Abbas, Mona AlHarbi and Mohammed Aljohani

Crystals 2022, 12(9), 1259; https://doi.org/10.3390/cryst12091259 - 5 Sep 2022

Cited by 7 | Viewed by 2618

Abstract

In the present work, pure and Cr-doped MoO₃ microrods were successfully prepared through the sol gel auto combustion method. The phase evaluation and microstructural, dielectric, and optical properties of synthesized samples were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), [...] Read more.

In the present work, pure and Cr-doped MoO₃ microrods were successfully prepared through the sol gel auto combustion method. The phase evaluation and microstructural, dielectric, and optical properties of synthesized samples were investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and an impedance analyzer (1 MHz–3 GHz). All the samples showed hexagonal structure with space group (P63). According to Vegard’s law, lattice parameters increase with the increase in chromium (Cr³⁺) contents. In addition, the Williamson–Hall (W–H) plot was drawn for evaluating the micro-strain (ε_W-H) and crystallite size (D_W-H) parameters. From microstructural analysis it was found that the size of microrods increased along with Cr³⁺ contents. Decreasing band gap energy was observed (from 2.98 to 2.71 eV) with increasing Cr³⁺ contents. The variation of the dielectric constant and tangent loss of MoO₃ microrods with respect to frequency were analyzed. Full article

(This article belongs to the Special Issue Advances in Optoelectric Functional Crystalline Materials)

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10 pages, 6126 KiB

Open AccessArticle

Large-Scale Synthesis h-BN Films on Copper-Nickel Alloy by Atmospheric Pressure Chemical Vapor Deposition

by Yuhan Feng, Yumin Zhang, Jipeng Liu, Ye Zhang and Yongshuai Xie

Crystals 2022, 12(7), 985; https://doi.org/10.3390/cryst12070985 - 15 Jul 2022

Cited by 6 | Viewed by 2386

Abstract

Due to its high thermal and chemical stability, excellent dielectric properties, unique optical properties, corrosion resistance, and oxidation resistance, the two-dimensional hexagonal boron nitride (h-BN) is often used in a thermal conductor protective layer in deep ultraviolet light-emitting detector fields. However, due to [...] Read more.

Due to its high thermal and chemical stability, excellent dielectric properties, unique optical properties, corrosion resistance, and oxidation resistance, the two-dimensional hexagonal boron nitride (h-BN) is often used in a thermal conductor protective layer in deep ultraviolet light-emitting detector fields. However, due to the complicated growth conditions of h-BN, it is often necessary to prepare h-BN by the CVD method in a high vacuum environment, which is limited to a certain extent in terms of film size and production cost. In order to solve this problem, we proposed a method to prepare h-BN thin films by atmospheric CVD (APCVD). This method does not need a vacuum environment, which reduces energy consumption and cost, and makes the operation simpler and the experimental environment safer. The preparation of high-quality h-BN film was carried out using a Cu-Ni alloy as the growth substrate. The growth process of h-BN film was studied, and the influence of growth parameters on the structure of the h-BN film was explored. The morphological features and elemental composition pairs of the samples were characterized and analyzed, which confirmed that the high-quality h-BN film could be successfully grown on the Cu-Ni alloy substrate by APCVD. The UV detection device prepared by using the prepared h-BN film as the photoresponse material had good photoresponse characteristics and performance stability. It provides a new idea for the low-cost preparation of large-scale h-BN. Full article

(This article belongs to the Special Issue Advances in Optoelectric Functional Crystalline Materials)

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15 pages, 4189 KiB

Open AccessArticle

Structural Defect Impact on Changing Optical Response and Raising Unpredicted Ferromagnetic Behaviour in (111) Preferentially Oriented Nanocrystalline NiO Films

by Amira Ben Gouider Trabelsi, Fatemah. H. Alkallas, Aicha Ziouche, Abdelwaheb Boukhachem, Mostefa Ghamnia and Habib Elhouichet

Crystals 2022, 12(5), 692; https://doi.org/10.3390/cryst12050692 - 12 May 2022

Cited by 6 | Viewed by 2718

Abstract

NiO thin films deposed on a glass substrate, “NiO/glass”, are successfully prepared using a spray pyrolysis technique (SPT) at 460 °C and characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray, Atomic force microscopy (AFM), spectroscopic ellipsometry (SE), Photoluminescence (PL) [...] Read more.

NiO thin films deposed on a glass substrate, “NiO/glass”, are successfully prepared using a spray pyrolysis technique (SPT) at 460 °C and characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray, Atomic force microscopy (AFM), spectroscopic ellipsometry (SE), Photoluminescence (PL) and diverse electric and magnetic studies. The structural investigation shows that the synthesized films crystallized in a cubic structure with (111) preferential orientation. The NiO layers exhibit a uniform grain of regular sizes with aggregates randomly distributed across their surface. The optical properties of the NiO thin films evidenced a normal optical dispersion as well as good transparency of the NiO films. An unpredicted ferromagnetic aspect was raised due to the high oxygen presence in the synthetized material. A high thermal dependency of the conductivity, as well as a semiconductor behavior of the grown NiO material, is also demonstrated. Full article

(This article belongs to the Special Issue Advances in Optoelectric Functional Crystalline Materials)

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13 pages, 4991 KiB

Open AccessArticle

Crystallization of Glasses Containing K₂O, PbO, BaO, Al₂O₃, B₂O₃, and TiO₂

by Patricia Ponce-Peña, María Azucena González-Lozano, Miguel Ángel Escobedo-Bretado, Diola Marina Núñez-Ramírez, Alicia Rodríguez-Pulido, Zoe V. Quiñones Jurado, Martha Poisot and Belkis Sulbarán-Rangel

Crystals 2022, 12(5), 574; https://doi.org/10.3390/cryst12050574 - 20 Apr 2022

Cited by 4 | Viewed by 3160

Abstract

The objective of this work was to obtain glass-ceramics from stable glasses, with a composition of barium, lead, and potassium titanate phases, for use as semiconductors. For this purpose, the glass-ceramic technique was used to control crystal growth and obtain a fine-grained microstructure. [...] Read more.

The objective of this work was to obtain glass-ceramics from stable glasses, with a composition of barium, lead, and potassium titanate phases, for use as semiconductors. For this purpose, the glass-ceramic technique was used to control crystal growth and obtain a fine-grained microstructure. Various glasses containing K₂O, PbO, BaO, Al₂O₃, B₂O₃, and TiO₂ were prepared using a melt-quenching method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) showed a single amorphous phase of all samples. Infrared spectra confirmed the presence of B-O bonds stretching vibrations of (B₃O₆)³⁻ boroxol rings and BO₃ triangles, as well as Ti-O stretching vibrations of (TiO_6/2) and (AlO_6/2) octahedral units. Thermal analyses confirmed the presence of one or more crystallization peaks in the range of 700 to 744 °C. On this base, they were heat-treated to promote crystal growth. XRD and SEM detected Ba₄Ti₁₂O₂₇, Ti₇O_13, and BaTiO₃ phases, homogeneously distributed throughout the material with fine crystallite size. In addition, crystallized glasses’ (glass-ceramics) properties were determined; the density values were 2.8–3.55 g/cm³; the chemical resistance to acidic and basic media was low; and the band-gap values were in the range of 2.88 to 3.05 eV. These results suggest that crystallized glasses may have application in photocatalysis. Full article

(This article belongs to the Special Issue Advances in Optoelectric Functional Crystalline Materials)

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9 pages, 18267 KiB

Open AccessCommunication

Studies on the Crystal Growth and Characterization of Large Size Sr:LCB Single Crystals

by Xuliang Zhang, Yue Li, Fangli Jing, Zhanggui Hu and Yicheng Wu

Crystals 2022, 12(4), 442; https://doi.org/10.3390/cryst12040442 - 22 Mar 2022

Cited by 2 | Viewed by 2203

Abstract

Extending the shortest second harmonic generation output wavelength of nonlinear optical crystals into the deep ultraviolet (UV) range is important for their application as frequency conversion devices for an advanced laser. The doping of ions with a large atomic number is believed to [...] Read more.

Extending the shortest second harmonic generation output wavelength of nonlinear optical crystals into the deep ultraviolet (UV) range is important for their application as frequency conversion devices for an advanced laser. The doping of ions with a large atomic number is believed to be an effective way to realize a shorter SHG output wavelength. In this work, large-sized Sr²⁺-doped La₂CaB₁₀O₁₉ (Sr:LCB) crystals with nominal ratios of 10%, 15% and 30% were grown by the top-seeded solution growth method. The measured lattice parameters of the grown Sr:LCB are nearly the same as that of the LCB crystal, and the rocking curves reveal that the grown Sr:LCB crystals are of high quality. Sr: LCB crystals have a UV cut-off edge of 168 nm. The refractive index of the Sr:LCB crystals was measured, based on which the Sellmeier equations of the Sr:LCB crystals were fitted. The calculated shortest SHG output wavelength for Type I phase matching is 270.5 nm, which is 17.5 nm shorter than that of LCB crystals (288 nm). The characterization results demonstrate that Sr:LCB is a potential nonlinear optical crystal for the deep UV range. Full article

(This article belongs to the Special Issue Advances in Optoelectric Functional Crystalline Materials)

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10 pages, 3260 KiB

Open AccessCommunication

Preparation of NbAs Single Crystal by the Seed Growth Process

by Yinchang Sun, Bojin Zhao, Zongju Huo, Hongjun Liu, Yongkuan Xu, Zhanggui Hu and Hailong Qiu

Crystals 2022, 12(2), 249; https://doi.org/10.3390/cryst12020249 - 11 Feb 2022

Cited by 2 | Viewed by 2578

Abstract

A Weyl semimetal is a novel crystal with low-energy electronic excitations that behave as Weyl fermions. It has received worldwide interest and was believed to have introduced the next era of condensed matter physics after graphene and three-dimensional topological insulators. However, it is [...] Read more.

A Weyl semimetal is a novel crystal with low-energy electronic excitations that behave as Weyl fermions. It has received worldwide interest and was believed to have introduced the next era of condensed matter physics after graphene and three-dimensional topological insulators. However, it is not easy to obtain a single large-sized crystal because there are many nucleations in the preparation process. A bottom-seed CVT growth method is proposed in this paper, and we acquired the large-sized, high-quality NbAs single crystals up to 4 × 3 × 3 mm³ finally. X-ray diffraction and STEM confirmed that they are tetragonal NbAs, which the key is to using the seed crystal in a vertical growth furnace. Notably, the photoelectric properties of the crystal are obtained under the existing conditions, which paves the way for follow-up work. Full article

(This article belongs to the Special Issue Advances in Optoelectric Functional Crystalline Materials)

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Review

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20 pages, 5682 KiB

Open AccessEditor’s ChoiceReview

Angular Quasi-Phase-Matching in Periodically Poled Uniaxial and Biaxial Crystals

by Yannick Petit, Alexandra Peña, Simon Joly, Dazhi Lu, Patricia Segonds and Benoît Boulanger

Crystals 2022, 12(7), 979; https://doi.org/10.3390/cryst12070979 - 13 Jul 2022

Cited by 1 | Viewed by 2705

Abstract

This article deals with a general description of Angular Quasi-Phase-Matching (AQPM) in uniaxial and biaxial crystals for second-order nonlinear optical interactions. Such an exhaustive and generalized angular-dependent approach of AQPM reveals new directions of propagation with efficient parametric frequency conversion. These AQPM solutions [...] Read more.

This article deals with a general description of Angular Quasi-Phase-Matching (AQPM) in uniaxial and biaxial crystals for second-order nonlinear optical interactions. Such an exhaustive and generalized angular-dependent approach of AQPM reveals new directions of propagation with efficient parametric frequency conversion. These AQPM solutions are studied by depicting the corresponding topologies and associated symmetries. The theoretical overview is fully validated and illustrated by measurements. We clearly demonstrate the benefits of such a generalized approach, both in the case of two emblematic periodically poled (PP) crystals: 5%MgO-doped PPLiNbO₃ (5%MgO:PPLN) and Rb-doped PPKTiOPO₄ (PPRKTP). These developments should stimulate new potential applications in nonlinear frequency conversion. Full article

(This article belongs to the Special Issue Advances in Optoelectric Functional Crystalline Materials)

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16 pages, 3263 KiB

Open AccessReview

Recent Trends in Elpasolite Single Crystal Scintillators for Radiation Detection

by Taiguang Jin, Shuwei Hao, Yunfei Shang, Zuotao Lei and Chunhui Yang

Crystals 2022, 12(7), 887; https://doi.org/10.3390/cryst12070887 - 22 Jun 2022

Cited by 13 | Viewed by 3688

Abstract

Scintillation detection has attracted great interest in nuclear medicine, nuclear radiation detection, high-energy physics, and non-destructive inspection. The elpasolite crystals with Ce³⁺ dopants are promising for these endeavors due to their modest light yield and extremely good proportionality when excited by the [...] Read more.

Scintillation detection has attracted great interest in nuclear medicine, nuclear radiation detection, high-energy physics, and non-destructive inspection. The elpasolite crystals with Ce³⁺ dopants are promising for these endeavors due to their modest light yield and extremely good proportionality when excited by the gamma ray. Moreover, the ⁶Li and ³⁵Cl isotopes in elpasolite crystals endow them with excellent neutron detection capability. These features allow not only a high energy resolution but also a high detection sensitivity. The elpasolite scintillators also enable the precisely dual detection of gamma/neutron signals through pulse height discrimination (PHD) or pulse shape discrimination (PSD). In this work, we review recent investigations on using the typical elpasolite scintillators, including Ce³⁺-doped Cs₂LiYCl₆ (CLYC), Cs₂LiLaCl₆ (CLLC), and Cs₂LiLaBr₆ (CLLB), for the monitoring of gamma rays and neutrons. The scintillation properties, detection mechanism, and elpasolite crystal structure are also discussed with the aim of improving high-energy ray detection ability. Full article

(This article belongs to the Special Issue Advances in Optoelectric Functional Crystalline Materials)

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24 pages, 8423 KiB

Open AccessReview

Heterostructured Nanoscale Photocatalysts via Colloidal Chemistry for Pollutant Degradation

by Caomeng Zhang, Shijie Zhong, Qun Li, Yuanpeng Ji, Liwei Dong, Guisheng Zhang, Yuanpeng Liu and Weidong He

Crystals 2022, 12(6), 790; https://doi.org/10.3390/cryst12060790 - 31 May 2022

Viewed by 2332

Abstract

With the further acceleration in the industrialization process, organic pollutants and gas pollution in the environment have posed severe threats to human health. It has been a global challenge regarding achieving an efficient solution to pollutant degradation. In such a context, photocatalysts have [...] Read more.

With the further acceleration in the industrialization process, organic pollutants and gas pollution in the environment have posed severe threats to human health. It has been a global challenge regarding achieving an efficient solution to pollutant degradation. In such a context, photocatalysts have attracted researchers’ attention for their simplicity, efficiency, cleanliness and low cost. However, the single photocatalyst is facing a research bottleneck owing to its narrow light absorption spectrum and high photocarrier recombination rate. Given that heterojunctions can achieve efficient separation of photogenerated carriers in space, constructing heterostructured photocatalysts has become the most perspective method to improve the performance of photocatalysts. Furthermore, nanoparticles prepared through colloidal chemistry have the characteristics of high dispersion, stability and adsorption, further enhancing the degradation efficiency of heterostructured photocatalysts. This article reviews the primary methods for preparing heterostructured photocatalysts through colloidal chemistry, classifies the heterojunction types by transport routes of photogenerated carriers and summarizes the recent progress of heterostructured photocatalysts in pollutant degradation. To implement environmental remediation, it is crucial to explore economical and efficient photocatalysts for practical applications. It is hoped that this review will stimulate further exploration of colloidal heterostructured photocatalysts for pollutant degradation. Full article

(This article belongs to the Special Issue Advances in Optoelectric Functional Crystalline Materials)

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Other

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8 pages, 1296 KiB

Open AccessBrief Report

Real-Time In-Situ Investigation of the Neutron Irradiation Resistance Ability of Nd³⁺-Doped Gd₃Sc₂Al₃O₁₂ Laser Crystal

by Yuxi Gao, Wenpeng Liu, Shoujun Ding, Yuanzhi Chen and Qingli Zhang

Crystals 2023, 13(1), 136; https://doi.org/10.3390/cryst13010136 - 12 Jan 2023

Cited by 1 | Viewed by 1814

Abstract

In optical crystals, photodarkening will occur after they were irradiated with high-energy particles, and such induced optical loss generally results in significant performance degradation whether they are used as passive or active optical elements. In the present study, the effects of neutron irradiation [...] Read more.

In optical crystals, photodarkening will occur after they were irradiated with high-energy particles, and such induced optical loss generally results in significant performance degradation whether they are used as passive or active optical elements. In the present study, the effects of neutron irradiation on the optical response of the Nd³⁺-doped Gd₃Sc₂Al₃O₁₂ (Nd:GSAG) single crystal has been revealed in real-time and in-situ. Transient and permanent transmittance reduction in the crystal induced by neutron radiation has been observed and the reduction mechanisms have been analyzed. The XRD characterization method demonstrated that the crystal structure remained constant both before and after neutron irradiation. Importantly, the X-ray photoelectron peak of the O 1s core level shifts to high binding energy, indicating that oxygen vacancies were produced in the crystal after irradiation with neutrons. Thus, the permanent reduction in the transmittance of the crystal after irradiation with neutrons can be attributed to the generation of oxygen vacancies in the crystal. To the best of our knowledge, it is the first time the damage types in rare earth oxide laser crystals caused by neutron irradiation were revealed. Full article

(This article belongs to the Special Issue Advances in Optoelectric Functional Crystalline Materials)

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