Pub Date : 2024-10-07DOI: 10.1016/j.jnoncrysol.2024.123255
The influence of the gradual replacement of Al2O3 with Y2O3 in alkali-containing silica glass sealants is studied with a detailed discussion of crystallization kinetics. Such substitution has a complex effect on Tg, Tsphere, THS, and Tflowing which might be connected with the role of yttrium in the glass network. An increase in the Y2O3 content is found to intensify crystallization, causing the growth of the crystalline phase fraction. At the same time, intense crystallization appears to have no pronounced effect on the coefficient of thermal expansion: its average increment after 1000 h of exposure at 850 °C in air atmosphere is <1‧10−6K−1. The only crystalline phase observed in samples with Y2O3 content greater than 2 wt % is suggested to be Na0.8Ca0.3Y0.4Zr0.22Si2.13O6 which is the Ca2+- and Zr4+-substituted isomorph of NaYSi2O6.
{"title":"Thermal behavior and crystallization of alkali aluminosilicate sealants for SOFC: Effect of Al2O3 to Y2O3 substitution","authors":"","doi":"10.1016/j.jnoncrysol.2024.123255","DOIUrl":"10.1016/j.jnoncrysol.2024.123255","url":null,"abstract":"<div><div>The influence of the gradual replacement of Al<sub>2</sub>O<sub>3</sub> with Y<sub>2</sub>O<sub>3</sub> in alkali-containing silica glass sealants is studied with a detailed discussion of crystallization kinetics. Such substitution has a complex effect on <em>T</em><sub>g</sub>, <em>T</em><sub>sphere</sub>, <em>T</em><sub>HS</sub>, and <em>T</em><sub>flowing</sub> which might be connected with the role of yttrium in the glass network. An increase in the Y<sub>2</sub>O<sub>3</sub> content is found to intensify crystallization, causing the growth of the crystalline phase fraction. At the same time, intense crystallization appears to have no pronounced effect on the coefficient of thermal expansion: its average increment after 1000 h of exposure at 850 °C in air atmosphere is <1‧10<sup>−6</sup> <em>K</em><sup>−1</sup>. The only crystalline phase observed in samples with Y<sub>2</sub>O<sub>3</sub> content greater than 2 wt % is suggested to be Na<sub>0.8</sub>Ca<sub>0.3</sub>Y<sub>0.4</sub>Zr<sub>0.22</sub>Si<sub>2.13</sub>O<sub>6</sub> which is the Ca<sup>2</sup><sup>+</sup>- and Zr<sup>4+</sup>-substituted isomorph of NaYSi<sub>2</sub>O<sub>6</sub>.</div></div>","PeriodicalId":16461,"journal":{"name":"Journal of Non-crystalline Solids","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-05DOI: 10.1016/j.jnoncrysol.2024.123247
We synthesized BaO-Bi2O3-P2O5 glass samples with different Nd concentrations by the melt-quenching technique. The concentrations were 1.0, 5.0, 10, 15, and 20 %. We obtained transparent and homogeneous samples for 1.0–10 % Nd concentrations. The 15 % Nd-doped sample was inhomogeneous, and the 20 % Nd-doped sample contained a crystalline phase. The photoluminescence (PL) and scintillation properties of the 1.0–10 % Nd-doped samples were investigated. The samples showed PL and scintillation peaks in the near-infrared region, which were due to 4f–4f transitions of Nd3+. We tested the X-ray dose rate response functions of the samples. The 10 % Nd-doped samples showed the most intensive response among the examined samples, and the lower detection limit of dose rate was 0.06 Gy/h with our setup.
{"title":"Near‐infrared scintillation properties of Nd-doped BaO-Bi2O3-P2O5 glasses","authors":"","doi":"10.1016/j.jnoncrysol.2024.123247","DOIUrl":"10.1016/j.jnoncrysol.2024.123247","url":null,"abstract":"<div><div>We synthesized BaO-Bi<sub>2</sub>O<sub>3</sub>-P<sub>2</sub>O<sub>5</sub> glass samples with different Nd concentrations by the melt-quenching technique. The concentrations were 1.0, 5.0, 10, 15, and 20 %. We obtained transparent and homogeneous samples for 1.0–10 % Nd concentrations. The 15 % Nd-doped sample was inhomogeneous, and the 20 % Nd-doped sample contained a crystalline phase. The photoluminescence (PL) and scintillation properties of the 1.0–10 % Nd-doped samples were investigated. The samples showed PL and scintillation peaks in the near-infrared region, which were due to 4f–4f transitions of Nd<sup>3+</sup>. We tested the X-ray dose rate response functions of the samples. The 10 % Nd-doped samples showed the most intensive response among the examined samples, and the lower detection limit of dose rate was 0.06 Gy/h with our setup.</div></div>","PeriodicalId":16461,"journal":{"name":"Journal of Non-crystalline Solids","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-05DOI: 10.1016/j.jnoncrysol.2024.123251
Lithium aluminosilicate (LAS) glass-ceramics are widely utilized in diverse application, owing to their outstanding properties such as high transparency, high fracture toughness and ultra-low thermal expansion. The development of LAS glass-ceramics has traditionally relied on the phase diagram to identify primary crystalline phases. However, this approach is limited by constrained composition ranges and unknown heating treatment parameters, hindering the efficient development of high-performance glass-ceramics. In this study, we establish a comprehensive small-scale database of LAS glass-ceramics, comprising 751 samples characterized by 27 compositions, nucleation temperature, nucleation time, crystallization temperature, crystallization time and 13 crystalline phases. We employ five algorithms, i.e. Random Forest (RF), eXtreme Gradient Boosting (XGBoost), Classification and Regression Trees (CART), K-Nearest Neighbors (K-NN) and Multi-Layer Perceptron (MLP) Classifier to predict the potential crystalline phases. Our results demonstrate that RF achieves the best overall performance, with the highest accuracy of 0.8609, the lowest hamming loss of 0.0142, and the highest micro F1 score of 0.9234. This work advances the understanding and prediction of crystalline phases in LAS glass-ceramics, providing valuable insights for the development and optimization of these materials.
锂铝硅酸盐（LAS）玻璃陶瓷具有高透明度、高断裂韧性和超低热膨胀等优异性能，因此被广泛应用于各种领域。传统上，LAS 玻璃陶瓷的开发主要依靠相图来确定主要晶相。然而，这种方法受限于有限的成分范围和未知的加热处理参数，阻碍了高性能玻璃陶瓷的高效开发。在本研究中，我们建立了一个全面的 LAS 玻璃陶瓷小规模数据库，其中包括 751 个样品，这些样品的特征包括 27 种成分、成核温度、成核时间、结晶温度、结晶时间和 13 种晶相。我们采用了五种算法，即随机森林 (RF)、极梯度提升 (XGBoost)、分类和回归树 (CART)、K-近邻 (K-NN) 和多层感知器 (MLP) 分类器来预测潜在的结晶相。结果表明，RF 的整体性能最佳，准确率最高，为 0.8609；hamming loss 最低，为 0.0142；micro F1 分数最高，为 0.9234。这项工作推进了对 LAS 玻璃陶瓷中晶相的理解和预测，为这些材料的开发和优化提供了宝贵的见解。
{"title":"Advancing the prediction of crystalline phases in glass-ceramics via machine learning","authors":"","doi":"10.1016/j.jnoncrysol.2024.123251","DOIUrl":"10.1016/j.jnoncrysol.2024.123251","url":null,"abstract":"<div><div>Lithium aluminosilicate (LAS) glass-ceramics are widely utilized in diverse application, owing to their outstanding properties such as high transparency, high fracture toughness and ultra-low thermal expansion. The development of LAS glass-ceramics has traditionally relied on the phase diagram to identify primary crystalline phases. However, this approach is limited by constrained composition ranges and unknown heating treatment parameters, hindering the efficient development of high-performance glass-ceramics. In this study, we establish a comprehensive small-scale database of LAS glass-ceramics, comprising 751 samples characterized by 27 compositions, nucleation temperature, nucleation time, crystallization temperature, crystallization time and 13 crystalline phases. We employ five algorithms, i.e. Random Forest (RF), eXtreme Gradient Boosting (XGBoost), Classification and Regression Trees (CART), K-Nearest Neighbors (K-NN) and Multi-Layer Perceptron (MLP) Classifier to predict the potential crystalline phases. Our results demonstrate that RF achieves the best overall performance, with the highest accuracy of 0.8609, the lowest hamming loss of 0.0142, and the highest micro F1 score of 0.9234. This work advances the understanding and prediction of crystalline phases in LAS glass-ceramics, providing valuable insights for the development and optimization of these materials.</div></div>","PeriodicalId":16461,"journal":{"name":"Journal of Non-crystalline Solids","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-05DOI: 10.1016/j.jnoncrysol.2024.123246
In this study, we investigated the effect of different compression routes on the lead metasilicate (PbSiO3) composition. Glass samples were compressed in a Belt press up to 5 GPa at room temperature (cold compression) and high temperatures (hot compression) up to 673 K, both at comparable experimental conditions concerning pressure and temperature gradients and times. The set of densified glasses was analyzed ex-situ by Brillouin, Raman and infrared spectroscopies, providing a multiscale structural probe. The dataset revealed a progressive decrease in the refractive index-weighted longitudinal sound velocities for the cold-compression and a minimum at about 450 K for hot-compression. Raman and infrared analyses indicate increasing depolymerization of the silicate network as an effect of densification, which is more pronounced at higher temperatures. Moreover, distinct mechanical properties are discussed regarding the inherent structural modifications resulting from the compression treatments.
在本研究中，我们研究了不同压缩路径对偏硅酸铅（PbSiO3）成分的影响。在室温（冷压缩）和高达 673 K 的高温（热压缩）条件下，玻璃样品在贝尔特压力机中被压缩至 5 GPa。布里渊光谱、拉曼光谱和红外光谱对这组致密化玻璃进行了原位分析，提供了多尺度结构探测。数据集显示，冷压缩时折射率加权纵向声速逐渐减小，热压缩时在约 450 K 时达到最小值。拉曼和红外分析表明，硅酸盐网络的解聚作用在不断增强，这是致密化的一种效应，在温度较高时更为明显。此外，还讨论了压缩处理导致的固有结构改变所带来的不同机械特性。
{"title":"Cold- and hot-densification of a depolymerized glass: A multiscale vibrational investigation of PbSiO3","authors":"","doi":"10.1016/j.jnoncrysol.2024.123246","DOIUrl":"10.1016/j.jnoncrysol.2024.123246","url":null,"abstract":"<div><div>In this study, we investigated the effect of different compression routes on the lead metasilicate (PbSiO<sub>3</sub>) composition. Glass samples were compressed in a Belt press up to 5 GPa at room temperature (cold compression) and high temperatures (hot compression) up to 673 K, both at comparable experimental conditions concerning pressure and temperature gradients and times. The set of densified glasses was analyzed <em>ex-situ</em> by Brillouin, Raman and infrared spectroscopies, providing a multiscale structural probe. The dataset revealed a progressive decrease in the refractive index-weighted longitudinal sound velocities for the cold-compression and a minimum at about 450 K for hot-compression. Raman and infrared analyses indicate increasing depolymerization of the silicate network as an effect of densification, which is more pronounced at higher temperatures. Moreover, distinct mechanical properties are discussed regarding the inherent structural modifications resulting from the compression treatments.</div></div>","PeriodicalId":16461,"journal":{"name":"Journal of Non-crystalline Solids","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-05DOI: 10.1016/j.jnoncrysol.2024.123250
Effect of single-doping by Ag2O (8 mol.%), Au2O (0.016 mol.%), Rb2O (8 mol.%), Nd2O3 (0.5 mol.%), Er2O3 (0.5 mol.%) on the structure and optical properties of zinc-phosphate (PZ) glasses was studied. Crystal-chemical similarity of local structures of the dopants in these glasses and in the revealed for them reference crystals of corresponding chemical composition was established by XANES/EXAFS. The specifics of this principle for each of the glasses was determined. Combining the obtained parameters of the embedded metal's local structure with TEM, absorption and photoluminescence (PL) data, the presence of color centers (ionic dimers, nanoclusters, nanoparticles (NPs)), their specific type and optical performances were determined. It was shown that Nd, Er are homogeneously distributed in as-prepared PZ glass without clustering, retaining their PL properties. Formation of Ag, Au, Rb color centers and Au NPs in as-prepared single-doped PZ glasses were studied.
{"title":"Local atomic structure and optical properties of zinc-phosphate glasses single-doped with Ag, Au, Rb, Nd and Er","authors":"","doi":"10.1016/j.jnoncrysol.2024.123250","DOIUrl":"10.1016/j.jnoncrysol.2024.123250","url":null,"abstract":"<div><div>Effect of single-doping by Ag<sub>2</sub>O (8 mol.%), Au<sub>2</sub>O (0.016 mol.%), Rb<sub>2</sub>O (8 mol.%), Nd<sub>2</sub>O<sub>3</sub> (0.5 mol.%), Er<sub>2</sub>O<sub>3</sub> (0.5 mol.%) on the structure and optical properties of zinc-phosphate (PZ) glasses was studied. Crystal-chemical similarity of local structures of the dopants in these glasses and in the revealed for them reference crystals of corresponding chemical composition was established by XANES/EXAFS. The specifics of this principle for each of the glasses was determined. Combining the obtained parameters of the embedded metal's local structure with TEM, absorption and photoluminescence (PL) data, the presence of color centers (ionic dimers, nanoclusters, nanoparticles (NPs)), their specific type and optical performances were determined. It was shown that Nd, Er are homogeneously distributed in as-prepared PZ glass without clustering, retaining their PL properties. Formation of Ag, Au, Rb color centers and Au NPs in as-prepared single-doped PZ glasses were studied.</div></div>","PeriodicalId":16461,"journal":{"name":"Journal of Non-crystalline Solids","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-04DOI: 10.1016/j.jnoncrysol.2024.123249
A series of Fe-based amorphous alloy wires with good formation ability, good flexibility, and a large specific surface area were prepared by the melt quenching method, which can be directly used as a self-supporting electrode for the oxygen evolution reaction (OER) of water electrolysis. By controlling the content of Mo, (Fe0.8Ni0.2)71Mo5P12C10B2 (Mo5), (Fe0.8Ni0.2)71Mo10P12C5B2 (Mo10) and (Fe0.8Ni0.2)71Mo15P10C2B2 (Mo15) alloy wires were prepared. It was found that Mo5 and Mo10 alloys still exhibit a fully amorphous structure, while the main body of Mo15 alloy comprises B2Fe3Ni3 and Mo6Ni6C phases. The electrochemical results showed that Mo15 alloy had the best intrinsic catalytic activity. The OER electrocatalytic performance of Mo15 was further improved by 1 h chemical etching after soaking in 0.5 M HNO3, which showed the overpotential was 239 mV and the Tafel slope was 40.6 mV/dec in 1 M KOH with a current density of 10 mA/cm2.
采用熔体淬火法制备了一系列具有良好形成能力、柔韧性和较大比表面积的铁基非晶合金丝，可直接用作水电解氧进化反应（OER）的自支撑电极。通过控制 Mo 的含量，制备了 (Fe0.8Ni0.2)71Mo5P12C10B2 (Mo5)、(Fe0.8Ni0.2)71Mo10P12C5B2 (Mo10) 和 (Fe0.8Ni0.2)71Mo15P10C2B2 (Mo15) 合金丝。研究发现，Mo5 和 Mo10 合金仍然呈现完全非晶结构，而 Mo15 合金的主体则由 B2Fe3Ni3 和 Mo6Ni6C 相组成。电化学结果表明，Mo15 合金具有最佳的内在催化活性。在 0.5 M HNO3 中浸泡 1 小时后进行化学蚀刻，Mo15 的 OER 电催化性能进一步提高，在 1 M KOH 中的过电位为 239 mV，Tafel 斜坡为 40.6 mV/dec，电流密度为 10 mA/cm2。
{"title":"Catalytic properties of Fe-based amorphous alloys with different Mo content after acid corrosion","authors":"","doi":"10.1016/j.jnoncrysol.2024.123249","DOIUrl":"10.1016/j.jnoncrysol.2024.123249","url":null,"abstract":"<div><div>A series of Fe-based amorphous alloy wires with good formation ability, good flexibility, and a large specific surface area were prepared by the melt quenching method, which can be directly used as a self-supporting electrode for the oxygen evolution reaction (OER) of water electrolysis. By controlling the content of Mo, (Fe<sub>0.8</sub>Ni<sub>0.2</sub>)<sub>71</sub>Mo<sub>5</sub>P<sub>12</sub>C<sub>10</sub>B<sub>2</sub> (Mo5), (Fe<sub>0.8</sub>Ni<sub>0.2</sub>)<sub>71</sub>Mo<sub>10</sub>P<sub>12</sub>C<sub>5</sub>B<sub>2</sub> (Mo10) and (Fe<sub>0.8</sub>Ni<sub>0.2</sub>)<sub>71</sub>Mo<sub>15</sub>P<sub>10</sub>C<sub>2</sub>B<sub>2</sub> (Mo15) alloy wires were prepared. It was found that Mo5 and Mo10 alloys still exhibit a fully amorphous structure, while the main body of Mo15 alloy comprises B<sub>2</sub>Fe<sub>3</sub>Ni<sub>3</sub> and Mo<sub>6</sub>Ni<sub>6</sub>C phases. The electrochemical results showed that Mo15 alloy had the best intrinsic catalytic activity. The OER electrocatalytic performance of Mo15 was further improved by 1 h chemical etching after soaking in 0.5 M HNO<sub>3</sub>, which showed the overpotential was 239 mV and the Tafel slope was 40.6 mV/dec in 1 M KOH with a current density of 10 mA/cm<sup>2</sup>.</div></div>","PeriodicalId":16461,"journal":{"name":"Journal of Non-crystalline Solids","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-04DOI: 10.1016/j.jnoncrysol.2024.123242
Conventional differential scanning calorimeters (DSC) are widely used to study thermal responses in glasses, such as crystallization, relaxation, and glass transition. However, their cooling () and heating () rates are limited, typically ranging from 0.01 to 2 K s−1. Flash-DSC overcomes this limitation by achieving much higher rates (up to ∼104 K s−1), allowing exploration of a wider range of experimental times, which is valuable for studying the glass transition phenomenon relevant to melts and glass industry. In this study, we utilized flash-DSC to investigate the thermal behavior of lithium disilicate (Li2Si2O5) and lead metasilicate (PbSiO3) glasses, employed here as examples of distinct fragility and glass-forming ability. We measured their limiting fictive temperatures (T’f), onset glass transition temperatures (Tg,onset), and the shift factors, which enable the retrieval of viscosity from DSC experiments. Our findings reveal that: i) the shift factor is composition-dependent; ii) when using a fixed heating rate for glass samples made with different cooling rates and the absolute values of , Tg,onset shifts to higher values as decreases, but when , Tg,onset shows no significant variation despite different T’f values due to relaxation on the heating path; iii) Li2Si2O5 glass exhibited non-overlapping heating curves in 8 repeated experiments after being cooled at the lowest rate, 50 K s−1, suggesting partial crystallization during cooling, while PbSiO3 exhibited overlapping heating curves, indicating its superior glass forming ability. Therefore, the critical cooling rate for vitrification of Li2Si2O5 was estimated to be above 50 K s−1. These findings indicate the power of flash-DSC to provide valuable insights into relaxation and crystallization phenomena.
{"title":"Flash-DSC provides valuable insights into glass relaxation and crystallization","authors":"","doi":"10.1016/j.jnoncrysol.2024.123242","DOIUrl":"10.1016/j.jnoncrysol.2024.123242","url":null,"abstract":"<div><div>Conventional differential scanning calorimeters (DSC) are widely used to study thermal responses in glasses, such as crystallization, relaxation, and glass transition. However, their cooling (<span><math><msub><mi>q</mi><mi>c</mi></msub></math></span>) and heating (<span><math><msub><mi>q</mi><mi>h</mi></msub></math></span>) rates are limited, typically ranging from 0.01 to 2 K s<sup>−1</sup>. Flash-DSC overcomes this limitation by achieving much higher rates (up to ∼10<sup>4</sup> K s<sup>−1</sup>), allowing exploration of a wider range of experimental times, which is valuable for studying the glass transition phenomenon relevant to melts and glass industry. In this study, we utilized flash-DSC to investigate the thermal behavior of lithium disilicate (Li<sub>2</sub>Si<sub>2</sub>O<sub>5</sub>) and lead metasilicate (PbSiO<sub>3</sub>) glasses, employed here as examples of distinct fragility and glass-forming ability. We measured their limiting fictive temperatures (<em>T’<sub>f</sub></em>), onset glass transition temperatures (<em>T<sub>g</sub></em><sub>,onset</sub>), and the shift factors, which enable the retrieval of viscosity from DSC experiments. Our findings reveal that: i) the shift factor is composition-dependent; ii) when using a fixed heating rate for glass samples made with different cooling rates and the absolute values of <span><math><mrow><msub><mi>q</mi><mi>h</mi></msub><mo>></mo><msub><mi>q</mi><mi>c</mi></msub></mrow></math></span>, <em>T<sub>g</sub></em><sub>,onset</sub> shifts to higher values as <span><math><msub><mi>q</mi><mi>c</mi></msub></math></span> decreases, but when <span><math><mrow><msub><mi>q</mi><mi>h</mi></msub><mo>≤</mo><msub><mi>q</mi><mi>c</mi></msub></mrow></math></span>, <em>T<sub>g</sub></em><sub>,onset</sub> shows no significant variation despite different <em>T’<sub>f</sub></em> values due to relaxation on the heating path; iii) Li<sub>2</sub>Si<sub>2</sub>O<sub>5</sub> glass exhibited non-overlapping heating curves in 8 repeated experiments after being cooled at the lowest rate, 50 K s<sup>−1</sup>, suggesting partial crystallization during cooling, while PbSiO<sub>3</sub> exhibited overlapping heating curves, indicating its superior glass forming ability. Therefore, the critical cooling rate for vitrification of Li<sub>2</sub>Si<sub>2</sub>O<sub>5</sub> was estimated to be above 50 K s<sup>−1</sup>. These findings indicate the power of flash-DSC to provide valuable insights into relaxation and crystallization phenomena.</div></div>","PeriodicalId":16461,"journal":{"name":"Journal of Non-crystalline Solids","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-03DOI: 10.1016/j.jnoncrysol.2024.123245
This work reports on isothermal sintering experiments, conducted with silica aerogel samples in a broad density range (∼0.025–0.277 kg/m3) made by the same process by varying the solvent-to-sol ratio, as well as samples made by different formulations used by several aerogel manufacturers. The latter comparison is deficient in the literature. Low-density (<0.05 kg/m3) aerogels were found to be significantly more resilient to sintering, which is consistent with established sintering theories. Unexpectedly large variability in the susceptibility to sintering was observed in similar density (∼0.1 kg/m3) aerogels made by different formulations and by different producers. All material made by utilizing a CO2 solvent exchange step prior to supercritical drying exhibited effects attributable to residual original solvent in the micropores. This alludes to an incomplete solvent exchange process. The materials were examined in the context of devising a methodology for producing an ultra-pure silica aerogel, a substance free of organic constituents, intended to serve NASA life detection mission needs.
{"title":"Sintering of different silica aerogels","authors":"","doi":"10.1016/j.jnoncrysol.2024.123245","DOIUrl":"10.1016/j.jnoncrysol.2024.123245","url":null,"abstract":"<div><div>This work reports on isothermal sintering experiments, conducted with silica aerogel samples in a broad density range (∼0.025–0.277 kg/m<sup>3</sup>) made by the same process by varying the solvent-to-sol ratio, as well as samples made by different formulations used by several aerogel manufacturers. The latter comparison is deficient in the literature. Low-density (<0.05 kg/m<sup>3</sup>) aerogels were found to be significantly more resilient to sintering, which is consistent with established sintering theories. Unexpectedly large variability in the susceptibility to sintering was observed in similar density (∼0.1 kg/m<sup>3</sup>) aerogels made by different formulations and by different producers. All material made by utilizing a CO<sub>2</sub> solvent exchange step prior to supercritical drying exhibited effects attributable to residual original solvent in the micropores. This alludes to an incomplete solvent exchange process. The materials were examined in the context of devising a methodology for producing an ultra-pure silica aerogel, a substance free of organic constituents, intended to serve NASA life detection mission needs.</div></div>","PeriodicalId":16461,"journal":{"name":"Journal of Non-crystalline Solids","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-02DOI: 10.1016/j.jnoncrysol.2024.123248
A series of fluorophosphate glasses with CdSe and CdSe+ZnSe are successfully synthesized. After heat treatment above the glass transition temperature, CdSe quantum dots with sizes 1.5–5.5 nm are formed. The luminescence spectra of CdSe quantum dots are analyzed at various temperatures, excitation energies and chemical composition of glass. The influence of selenium content on the growth features of quantum dots is shown. The size dependence of luminescence quantum yield on the QDs size is found. The 2.0–2.5 nm-sized QDs demonstrate trap emission in the region of 1.7–1.85 eV with a maximum quantum yield of 60 %. It is found that only a broad band due to the transition from the low state of the conduction band and the shallow donor trap states to the deep accepter trap levels is observed. This broad emission band is observed at any selenium cadmium ratio and zinc introduction.
{"title":"Controlling the luminescence of CdSe quantum dots in the fluorinephosphate glass","authors":"","doi":"10.1016/j.jnoncrysol.2024.123248","DOIUrl":"10.1016/j.jnoncrysol.2024.123248","url":null,"abstract":"<div><div>A series of fluorophosphate glasses with CdSe and CdSe+ZnSe are successfully synthesized. After heat treatment above the glass transition temperature, CdSe quantum dots with sizes 1.5–5.5 nm are formed. The luminescence spectra of CdSe quantum dots are analyzed at various temperatures, excitation energies and chemical composition of glass. The influence of selenium content on the growth features of quantum dots is shown. The size dependence of luminescence quantum yield on the QDs size is found. The 2.0–2.5 nm-sized QDs demonstrate trap emission in the region of 1.7–1.85 eV with a maximum quantum yield of 60 %. It is found that only a broad band due to the transition from the low state of the conduction band and the shallow donor trap states to the deep accepter trap levels is observed. This broad emission band is observed at any selenium cadmium ratio and zinc introduction.</div></div>","PeriodicalId":16461,"journal":{"name":"Journal of Non-crystalline Solids","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-01DOI: 10.1016/j.jnoncrysol.2024.123234
Structure of borosilicate glasses with varying Li2O contents were investigated using Magic Angle Spinning (MAS) Nuclear Magnetic Resonance (NMR), employing 6Li, 11B, 23Na, 27Al and 29Si nuclei. 11B MAS NMR revealed that increasing Li2O contents result in formation of [BO4]− sites at the expense of BO3. 11B{6Li} and 27Al{6Li} dipolar heteronuclear multiple quantum correlation (D-HMQC) NMR revealed Li as a charge compensator for anionic tetrahedral sites with increased Li. 11B{6Li} J-coupling mediated HMQC NMR suggested the possible association of Li with non-bridging oxygens on Q2 and Q3 sites, indicating its dual role in the glass network. 29Si and 23Na MAS NMR spectra showed depolymerisation of the silicate network and shortening of Na-O bond lengths with increased Li. NMR results are supported by Raman spectroscopy and thermal analysis that indicate depolymerisation of the silicate network and a reduction in glass transition temperature at higher Li content.
{"title":"Effect of lithium concentration on the network connectivity of nuclear waste glasses","authors":"","doi":"10.1016/j.jnoncrysol.2024.123234","DOIUrl":"10.1016/j.jnoncrysol.2024.123234","url":null,"abstract":"<div><div>Structure of borosilicate glasses with varying Li<sub>2</sub>O contents were investigated using Magic Angle Spinning (MAS) Nuclear Magnetic Resonance (NMR), employing <sup>6</sup>Li, <sup>11</sup>B, <sup>23</sup>Na, <sup>27</sup>Al and <sup>29</sup>Si nuclei. <sup>11</sup>B MAS NMR revealed that increasing Li<sub>2</sub>O contents result in formation of [BO<sub>4</sub>]<sup>−</sup> sites at the expense of BO<sub>3</sub>. <sup>11</sup>B{<sup>6</sup>Li} and <sup>27</sup>Al{<sup>6</sup>Li} dipolar heteronuclear multiple quantum correlation (D-HMQC) NMR revealed Li as a charge compensator for anionic tetrahedral sites with increased Li. <sup>11</sup>B{<sup>6</sup>Li} J-coupling mediated HMQC NMR suggested the possible association of Li with non-bridging oxygens on Q<sup>2</sup> and Q<sup>3</sup> sites, indicating its dual role in the glass network. <sup>29</sup>Si and <sup>23</sup>Na MAS NMR spectra showed depolymerisation of the silicate network and shortening of Na-O bond lengths with increased Li. NMR results are supported by Raman spectroscopy and thermal analysis that indicate depolymerisation of the silicate network and a reduction in glass transition temperature at higher Li content.</div></div>","PeriodicalId":16461,"journal":{"name":"Journal of Non-crystalline Solids","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142358066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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