Inorganics

Research

12 pages, 8374 KiB

Open AccessArticle

Fabrication and Luminescent Properties of Er-Doped Sr₅(PO₄)₃F Ceramics

by Dmitry Permin, Marsel Nazmutdinov, Sergey Kurashkin, Stanislav Balabanov, Alexander Belyaev, Anastasia Novikova and Vitaliy Koshkin

Inorganics 2023, 11(2), 57; https://doi.org/10.3390/inorganics11020057 - 25 Jan 2023

Cited by 3 | Viewed by 1082

Abstract

Nanopowders of strontium fluoroapatite Sr₅(PO₄)₃F (SFAP) were synthesized using a co-precipitation method with different starting strontium compounds. Based on the data of XRD, BET and SEM measurements, the nitrate-derived powders were chosen as the least agglomerated. The [...] Read more.

Nanopowders of strontium fluoroapatite Sr₅(PO₄)₃F (SFAP) were synthesized using a co-precipitation method with different starting strontium compounds. Based on the data of XRD, BET and SEM measurements, the nitrate-derived powders were chosen as the least agglomerated. The SFAP powders were hot pressed at 1000 °C to ceramic samples with a transmittance up to 82% in a mid-IR region. The designed approach was adopted to prepare 2 mol % of Er-doped SFAP powders and ceramics. It was established that Er:SFAP ceramics have luminescence in the range of 1.5–1.7 μm, the intensity of which increases with the calcination temperature of the initial powders. Full article

(This article belongs to the Special Issue Oxide Optical Ceramics and Precursor Powders Preparation for Luminescence and Laser Applications)

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12 pages, 10310 KiB

Open AccessArticle

Experience of Using DLS to Study the Particle Sizes of Active Component in the Catalysts Based on the Oxide and Non-Oxide Supports

by Yurii V. Larichev

Inorganics 2022, 10(12), 248; https://doi.org/10.3390/inorganics10120248 - 8 Dec 2022

Cited by 1 | Viewed by 2162

Abstract

The present study reports the use of the dynamic light scattering (DLS) method to analyze metal nanoparticle sizes in supported catalysts (as a model system for different metal-oxide nanocomposites, ceramics, etc.). The selective dissolution of matrices has been used to transform solids to [...] Read more.

The present study reports the use of the dynamic light scattering (DLS) method to analyze metal nanoparticle sizes in supported catalysts (as a model system for different metal-oxide nanocomposites, ceramics, etc.). The selective dissolution of matrices has been used to transform solids to sols for DLS analysis. DLS/STS (from solid to sol) technique was tested on a wide number of different sets of supported metal catalysts (Pt, Pd, Ru metals and Al₂O₃, SiO₂, TiO₂, C₃N₄, carbon and polymers as supports). The transmission electron microscopy and X-ray diffraction (TEM/XRD) results for the initial supported catalysts and the DLS results for the sols prepared from them showed good agreement with each other. Moreover, it has been shown that this approach can identify the minor contamination of catalysts by large particles or aggregates which are difficult to detect by TEM/XRD. Full article

(This article belongs to the Special Issue Oxide Optical Ceramics and Precursor Powders Preparation for Luminescence and Laser Applications)

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12 pages, 2818 KiB

Open AccessArticle

The Electrophoretic Deposition of Nanopowders Based on Yttrium Oxide for Bulk Ceramics Fabrication

by Elena Kalinina and Maxim Ivanov

Inorganics 2022, 10(12), 243; https://doi.org/10.3390/inorganics10120243 - 6 Dec 2022

Cited by 2 | Viewed by 1232

Abstract

In the present work, a study was carried out to investigate the key factors that determine the uniformity, mass, thickness, and density of compacts obtained from nanopowders of solid solutions of yttrium and lanthanum oxides ((La_xY_1−x)₂O₃ [...] Read more.

In the present work, a study was carried out to investigate the key factors that determine the uniformity, mass, thickness, and density of compacts obtained from nanopowders of solid solutions of yttrium and lanthanum oxides ((La_xY_1−x)₂O₃) with the help of the electrophoretic deposition (EPD). Nanopowders were obtained by laser ablation of a mixture of powders of yttrium oxide and lanthanum oxide in air. The implemented mechanisms of the EPD and factors of stability of alcohol suspensions are analyzed. It has been shown that acetylacetone with a concentration of 1 mg/m² can be used as a dispersant for stabilization of isopropanol suspensions of the nanoparticles during the EPD. It was shown that the maximum density of dry compacts with a thickness of 2.4 mm reaches 37% of theoretical when EPD is performed in vertical direction from a suspension of nanopowders with addition of acetylacetone. Full article

(This article belongs to the Special Issue Oxide Optical Ceramics and Precursor Powders Preparation for Luminescence and Laser Applications)

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9 pages, 3711 KiB

Open AccessArticle

Synthesis of Y₃Al₅O₁₂:Ce Powders for X-ray Luminescent Diamond Composites

by Sergey V. Kuznetsov, Vadim S. Sedov, Artem K. Martyanov, Dmitrii S. Vakalov, Ludmila V. Tarala, Ivan A. Tiazhelov and Kirill N. Boldyrev

Inorganics 2022, 10(12), 240; https://doi.org/10.3390/inorganics10120240 - 5 Dec 2022

Cited by 3 | Viewed by 1099

Abstract

A concentration series of Y₃Al₅O₁₂:Ce solid solutions were prepared, and the composition demonstrating the highest X-ray luminescence intensity of cerium was identified. Based on the best composition, a series of luminescent diamond–Y₃Al₅O₁₂ [...] Read more.

A concentration series of Y₃Al₅O₁₂:Ce solid solutions were prepared, and the composition demonstrating the highest X-ray luminescence intensity of cerium was identified. Based on the best composition, a series of luminescent diamond–Y₃Al₅O₁₂:Ce composite films were synthesized using microwave plasma-assisted chemical vapor deposition (CVD) in methane–hydrogen gas mixtures. Variations in the amounts of the embedded Y₃Al₅O₁₂:Ce powders allowed for the fine-tuning of the luminescence intensity of the composite films. Full article

(This article belongs to the Special Issue Oxide Optical Ceramics and Precursor Powders Preparation for Luminescence and Laser Applications)

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16 pages, 16467 KiB

Open AccessArticle

Cold Sintering Process of Zinc Oxide Ceramics: Powder Preparation and Sintering Conditions Effects on Final Microstructure

by Andrey V. Smirnov, Maxim V. Kornyushin, Anastasia A. Kholodkova, Sergey A. Melnikov, Artem D. Stepanov, Elena V. Fesik and Yurii D. Ivakin

Inorganics 2022, 10(11), 197; https://doi.org/10.3390/inorganics10110197 - 5 Nov 2022

Cited by 5 | Viewed by 1999

Abstract

Although the activating effect of an acetate medium in the cold sintering process of zinc oxide ceramics is well known, some problems need to be solved on the effect of process conditions and the initial powder’s preparation methods on the ceramic’s density and [...] Read more.

Although the activating effect of an acetate medium in the cold sintering process of zinc oxide ceramics is well known, some problems need to be solved on the effect of process conditions and the initial powder’s preparation methods on the ceramic’s density and microstructure. This article describes an effect of the zinc acetate introduction method, its concentration in zinc oxide powder as well as that of the die sealing configuration on the density and microstructure of zinc oxide ceramics obtained by the cold sintering process at 244 °C. The activating additive of zinc acetate was applied in two ways: (1) impregnation in aqueous solution and (2) impregnation with subsequent treatment in water vapor. Zinc oxide powders and ceramics were analyzed using SEM, TGA/DSC/MS and XRD to reveal the effect of powder pre-treatment and sintering conditions on the material microstructure. Cold sintered ZnO ceramics samples with a relative density up to 0.99 and with average grain sizes from 0.28 to 1.71 μm were obtained. The die sealing by two Teflon sealing rings appeared to be the most effective. Full article

(This article belongs to the Special Issue Oxide Optical Ceramics and Precursor Powders Preparation for Luminescence and Laser Applications)

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13 pages, 5792 KiB

Open AccessArticle

Laser Ablation Synthesis and Characterization of Tb₂O₃ Nanoparticles for Magneto-Optical Ceramics

by Roman N. Maksimov, Vladimir V. Osipov, Garegin R. Karagedov, Vyacheslav V. Platonov, Artem S. Yurovskikh, Albert N. Orlov, Alfiya V. Spirina and Vladislav A. Shitov

Inorganics 2022, 10(10), 173; https://doi.org/10.3390/inorganics10100173 - 18 Oct 2022

Cited by 2 | Viewed by 1454

Abstract

In this study, nano-sized individual Tb₂O₃ particles synthesized by the laser ablation method were extensively characterized and assessed as suitable precursors for the fabrication of transparent magneto-optical ceramics without requiring the introduction of grain growth inhibitors and stabilizing additives. The [...] Read more.

In this study, nano-sized individual Tb₂O₃ particles synthesized by the laser ablation method were extensively characterized and assessed as suitable precursors for the fabrication of transparent magneto-optical ceramics without requiring the introduction of grain growth inhibitors and stabilizing additives. The as-produced powder comprised 13 nm particles with a spherical shape and monoclinic crystal structure, whose full transformation into cubic phase was achieved after heating at 950 °C and 700 °C under vacuum and Ar gas, respectively. After subjecting the nanopowder compact to pre-sintering at 1350 °C, the microstructural features were investigated along with their correlation to the optical transmittance of Tb₂O₃ ceramic hot isostatically pressed (HIPed) for 2 h at 1450 °C under 200 MPa. The as-HIPed sample had a brownish color, with an optical transmittance of 65.3% at a wavelength of 1060 nm and an average grain size of 14 μm. The Verdet constant measured at wavelengths of 633 nm and 1060 nm was 471 rad T⁻¹ m⁻¹ and 142 rad T⁻¹ m⁻¹ to confirm a very high content of magneto-active Tb³⁺ ions. The obtained results indicate that laser ablation synthesis of nanoparticles followed by pre-sintering and HIP is a promising approach for the manufacture of magneto-optical Tb₂O₃ ceramics without specific sintering aids. Full article

(This article belongs to the Special Issue Oxide Optical Ceramics and Precursor Powders Preparation for Luminescence and Laser Applications)

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8 pages, 1667 KiB

Open AccessArticle

Judd-Ofelt Analysis of High Erbium Content Yttrium-Aluminum and Yttrium-Scandium-Aluminum Garnet Ceramics

by Vadim Zhmykhov, Elena Dobretsova, Vladimir S. Tsvetkov, Marina Nikova, Irina Chikulina, Dmitry Vakalov, Vitaly Tarala, Yurii Pyrkov, Sergey Kuznetsov and Vladimir Tsvetkov

Inorganics 2022, 10(10), 170; https://doi.org/10.3390/inorganics10100170 - 11 Oct 2022

Cited by 2 | Viewed by 1485

Abstract

The Er_1.5Y_1.5Al₅O₁₂ (Er:YAG) and (Er_1.43Y_1.43Sc_0.14)(Sc_0.24Al_1.76)Al₃O₁₂ (Er:YSAG) ceramics have been characterized using the Judd-Ofelt (JO) theory. The line strengths and oscillator strengths of several [...] Read more.

The Er_1.5Y_1.5Al₅O₁₂ (Er:YAG) and (Er_1.43Y_1.43Sc_0.14)(Sc_0.24Al_1.76)Al₃O₁₂ (Er:YSAG) ceramics have been characterized using the Judd-Ofelt (JO) theory. The line strengths and oscillator strengths of several transitions from the ground state ⁴I_15/2 to excited state manifolds have been evaluated from transmittance spectra measured at room temperature (300 K). The JO parameters have been calculated, and the values of the radiative decays rate and the radiative lifetimes for the ⁴I_13/2 excited state, and the luminescence cross-section of ⁴I_15/2 → ⁴I_13/2 in Er-doped ceramic samples have been established. We have traced the influence of Sc³⁺ inclusion on spectroscopic properties and crystal quality and estimate prospects of application in laser systems. Full article

(This article belongs to the Special Issue Oxide Optical Ceramics and Precursor Powders Preparation for Luminescence and Laser Applications)

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10 pages, 1782 KiB

Open AccessArticle

Structural and Luminescent Peculiarities of Spark Plasma Sintered Transparent MgAl₂O₄ Spinel Ceramics Doped with Cerium Ions

by Damir Valiev, Sergey Stepanov, Vladimir Paygin, Oleg Khasanov, Edgar Dvilis and Lin Chaolu

Inorganics 2022, 10(10), 153; https://doi.org/10.3390/inorganics10100153 - 26 Sep 2022

Cited by 3 | Viewed by 1472

Abstract

In the present study, the concentration series of MgAl₂O₄:Ce³⁺ ceramics have been fabricated by the Spark Plasma Sintering (SPS) method. Cerium-doping concentration was varied within a range of 0.1–5 wt.%. The prepared ceramics have been tested using the [...] Read more.

In the present study, the concentration series of MgAl₂O₄:Ce³⁺ ceramics have been fabricated by the Spark Plasma Sintering (SPS) method. Cerium-doping concentration was varied within a range of 0.1–5 wt.%. The prepared ceramics have been tested using the various experimental techniques: X-ray diffraction (XRD), scanning electron microscopy, as well as optical and cathodoluminescence spectroscopy. According to XRD, all synthesized samples are biphasic with structural impurities. The cerium ion concentration effect on the cathodoluminescent characteristics of MgAl₂O₄:Ce³⁺ ceramics has been studied in terms of emission intensity and decay time. Before annealing the concentration, quenching is observed. The optimal doping Ce³⁺ concentration was determined to be 5 wt.% after temperature annealing at 1300 °C. The successfully prepared spinel ceramics could be potentially applying for high-energy electrons detection. Full article

(This article belongs to the Special Issue Oxide Optical Ceramics and Precursor Powders Preparation for Luminescence and Laser Applications)

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13 pages, 3604 KiB

Open AccessArticle

Effect of the Synthesis Conditions on the Morphology, Luminescence and Scintillation Properties of a New Light Scintillation Material Li₂CaSiO₄:Eu²⁺ for Neutron and Charged Particle Detection

by Ilia Komendo, Vitaly Mechinsky, Andrei Fedorov, Georgy Dosovitskiy, Victor Schukin, Daria Kuznetsova, Marina Zykova, Yury Velikodny and Mikhail Korjik

Inorganics 2022, 10(9), 127; https://doi.org/10.3390/inorganics10090127 - 30 Aug 2022

Cited by 2 | Viewed by 1589

Abstract

In the present article, the influence of the activator concentration and impurity content of raw materials on the luminescence and scintillation properties of Li₂CaSiO₄ was studied. Polycrystalline powder material was obtained by the sol–gel method. It was shown that europium [...] Read more.

In the present article, the influence of the activator concentration and impurity content of raw materials on the luminescence and scintillation properties of Li₂CaSiO₄ was studied. Polycrystalline powder material was obtained by the sol–gel method. It was shown that europium had limited solubility in the host lattice with a limiting concentration proximate to 0.014 formula units. The maximum intensity of photoluminescence was observed with a divalent europium concentration of 0.002 formula units; the light yield under alpha-particle excitation was measured to be 21,600 photons/MeV for ~200 μm of coating, and under neutron excitation, it was calculated to be 103,800 photons/n, the scintillation kinetics was characterized by an effective decay time of 157 ns. These properties and the transparency in the visible spectrum make it possible to produce scintillation screens with a coating of Li₂CaSiO₄ for detecting neutrons, alpha particles and low-energy beta radiation. The low Z_eff (~15) of this compound makes it less sensitive to gamma rays. The 480 nm blue emission peak makes this material compatible with most commercial PMT photocathodes, CCD cameras and silicon photomultipliers, which have a maximum quantum efficiency in the blue–green spectral region. Full article

(This article belongs to the Special Issue Oxide Optical Ceramics and Precursor Powders Preparation for Luminescence and Laser Applications)

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8 pages, 1153 KiB

Open AccessArticle

Thermal Conductivity of Yttria-Gadolinia Solid Solution Optical Ceramics in the Temperature Range 50–300 K

by Stanislav Balabanov, Timofey Evstropov, Dmitry Permin, Olga Postnikova, Alexander Praded and Pavel Popov

Inorganics 2022, 10(6), 78; https://doi.org/10.3390/inorganics10060078 - 6 Jun 2022

Cited by 2 | Viewed by 1688

Abstract

This study looked at the thermal conductivity of translucent (Y_1−xGd_x)₂O₃ (where 0 ≤ x ≤ 1) solid solution ceramics in the temperature range from 50 K to 300 K. The samples were obtained by hot [...] Read more.

This study looked at the thermal conductivity of translucent (Y_1−xGd_x)₂O₃ (where 0 ≤ x ≤ 1) solid solution ceramics in the temperature range from 50 K to 300 K. The samples were obtained by hot pressing from high-purity nanopowders at 1600 °C, no sintering additives were used. Compositions with cubic syngony (x ≤ 0.7) and a monoclinic one (x ≥ 0.9) were investigated. Furthermore, a dense sample of cubic Gd₂O₃ with a LiF sintering additive was obtained and its thermal conductivity was determined (k = 11.7 W/(m K) at 300 K). It was shown that in the range of solid solution ceramic compositions 0.2 ≤ x ≤ 0.7, the thermal conductivity was practically unchanged and close to the value k ≈ 5 W/(m K) at 300 K. Full article

(This article belongs to the Special Issue Oxide Optical Ceramics and Precursor Powders Preparation for Luminescence and Laser Applications)

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