Pub Date : 2023-12-08DOI: 10.13036/17533562.63.2.20
A. Ihyadn, A. Lahmar, I. Luk’yanchuk, D. Mezzane, L. Bih, A. Alimoussa, M. Amjoud, M. El Marssi
A series of (1−x)[(2BaO–0·5Na2O)–1P2O5] –xNb2O5 (BNPN, x=0·41, 0·43, 0·45, 0·48) glass-ceramics based on phosphate glasses have been prepared via a controlled-crystallisation route. The structure, dielectric properties, interfacial polarisation and energy storage properties were systematically investigated. The x-ray diffraction results showed the simultaneous presence of Ba2NaNb5O15 tungsten bronze structure (TTB) and the NaNbO3 perovskite. A stable dielectric constant over a temperature range from 25–200°C, low dielectric losses less than 0·03 and excellent frequency stability at room temperature were obtained. The decrease of niobium content promoted the TTB crystallisation with improvement of the high dielectric properties of the system. The optimum of the dielectric constant and recoverable energy storage density were obtained for BNP41 crystallised at 1000°C. Analyses of the complex impedance indicated that the niobium content and crystallisation temperature affect the interfacial polarisation.
{"title":"Structural, dielectric and energy storage properties of BaO–Na2O–Nb2O5–P2O5 glass-ceramics","authors":"A. Ihyadn, A. Lahmar, I. Luk’yanchuk, D. Mezzane, L. Bih, A. Alimoussa, M. Amjoud, M. El Marssi","doi":"10.13036/17533562.63.2.20","DOIUrl":"https://doi.org/10.13036/17533562.63.2.20","url":null,"abstract":"A series of (1−x)[(2BaO–0·5Na2O)–1P2O5] –xNb2O5 (BNPN, x=0·41, 0·43, 0·45, 0·48) glass-ceramics based on phosphate glasses have been prepared via a controlled-crystallisation route. The structure, dielectric properties, interfacial polarisation and energy storage properties were systematically investigated. The x-ray diffraction results showed the simultaneous presence of Ba2NaNb5O15 tungsten bronze structure (TTB) and the NaNbO3 perovskite. A stable dielectric constant over a temperature range from 25–200°C, low dielectric losses less than 0·03 and excellent frequency stability at room temperature were obtained. The decrease of niobium content promoted the TTB crystallisation with improvement of the high dielectric properties of the system. The optimum of the dielectric constant and recoverable energy storage density were obtained for BNP41 crystallised at 1000°C. Analyses of the complex impedance indicated that the niobium content and crystallisation temperature affect the interfacial polarisation.","PeriodicalId":49696,"journal":{"name":"Physics and Chemistry of Glasses-European Journal of Glass Science and Technology Part B","volume":"25 6 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78432798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2023-04-01DOI: 10.13036/17533562.64.2.22
S. Sander, F. Syrowatka, D. Enke, H. Roggendorf
Sodium borosilicate glasses are processed to porous glasses as well as to Vycor™ type glasses via phase separation and selective leaching. Both materials consist mainly of SiO2. Thermal treatment inducing phase separation is crucial for microstructure development. Sodium borosilicate glasses with molar compositions of 8Na2O.21B2O3.71SiO2 and 8Na2O.28B2O3.64 SiO2 were melted, rapidly cooled and investigated by thermal analysis and scanning electron microscopy. The glasses were thermally treated for 120 h at 630 to 730°C, and then leached, first for 72 h in 0·1 M HCl at 60°C, and subsequently for 4 h in 0·5 M NaOH at 30°C. X-ray fluorescence was applied to characterise the chemical compositions. Microstructure development was first analysed by differential thermal analysis and dilatometry, and the pore structure was characterised by Hg porosimetry and N2 adsorption. Heat treated glasses were then analysed by low voltage scanning electron microscopy, combined in one case with chemical analysis by energy dispersive x-ray analysis. The results are discussed with respect to phase relations. After long term heat treatment, at least three phases exist in two independent metastable two-phase equilibria on different size and time scales.
硼硅酸钠玻璃通过相分离和选择性浸出加工成多孔玻璃和Vycor™型玻璃。这两种材料主要由SiO2组成。热处理诱导相分离是组织发育的关键。将8Na2O.21B2O3.71SiO2和8Na2O.28B2O3.64 SiO2的硼硅酸钠玻璃熔化，快速冷却，用热分析和扫描电镜对其进行了研究。玻璃在630 ~ 730℃下热处理120 h，然后在60℃下0.1 M HCl中浸出72 h，随后在30℃下0.5 M NaOH中浸出4 h。用x射线荧光测定了化学成分。首先用差热分析和膨胀法分析了微观结构的发育，用汞孔隙度法和氮气吸附法对孔隙结构进行了表征。然后用低压扫描电子显微镜对热处理过的玻璃进行分析，在一个案例中结合了能量色散x射线分析的化学分析。从相关系的角度对结果进行了讨论。经过长期热处理后，在不同尺寸和时间尺度上，至少有三个相存在于两个独立的亚稳态两相平衡中。
{"title":"Phase relations in heat treated sodium borosilicate glasses","authors":"S. Sander, F. Syrowatka, D. Enke, H. Roggendorf","doi":"10.13036/17533562.64.2.22","DOIUrl":"https://doi.org/10.13036/17533562.64.2.22","url":null,"abstract":"Sodium borosilicate glasses are processed to porous glasses as well as to Vycor™ type glasses via phase separation and selective leaching. Both materials consist mainly of SiO2. Thermal treatment inducing phase separation is crucial for microstructure development. Sodium borosilicate glasses with molar compositions of 8Na2O.21B2O3.71SiO2 and 8Na2O.28B2O3.64 SiO2 were melted, rapidly cooled and investigated by thermal analysis and scanning electron microscopy. The glasses were thermally treated for 120 h at 630 to 730°C, and then leached, first for 72 h in 0·1 M HCl at 60°C, and subsequently for 4 h in 0·5 M NaOH at 30°C. X-ray fluorescence was applied to characterise the chemical compositions. Microstructure development was first analysed by differential thermal analysis and dilatometry, and the pore structure was characterised by Hg porosimetry and N2 adsorption. Heat treated glasses were then analysed by low voltage scanning electron microscopy, combined in one case with chemical analysis by energy dispersive x-ray analysis. The results are discussed with respect to phase relations. After long term heat treatment, at least three phases exist in two independent metastable two-phase equilibria on different size and time scales.","PeriodicalId":49696,"journal":{"name":"Physics and Chemistry of Glasses-European Journal of Glass Science and Technology Part B","volume":"4 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74528350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2023-04-01DOI: 10.13036/17533562.64.2.12
B. S. Narayana Devara, Y. C. Ratnakaram, M. Kumar
Neodymium doped fluorophosphate (FP:Nd3+) glasses with different chemical compositions (59NH4H2PO4+15ZnO +15BaF2+10X+1·0NdF3 (X=LiF, NaF, CaF2, SrF2, AlF3)) were prepared by melt quenching. Their structures and spectroscopic properties were studied using x-ray diffraction, FTIR, FT-Raman and 31P, 27Al MAS NMR techniques. Various structural groups were identified using FTIR and FT-Raman spectra. The depolymerisation of metaphosphate chains are described by the decrease of Q2 tetrahedral sites allowing the formation of pyrophosphate groups revealed by 31P MAS NMR spectroscopic studies. Optical properties were studied using absorption and photoluminescence spectroscopy. Judd–Ofelt intensity parameters Ωλ (λ=2, 4 and 6) were estimated from absorption spectra. Radiative parameters such as transition probabilities (A), radiative lifetimes (τR), integrated absorption cross-sections (Σ) and branching ratios (βR) were calculated. Two emission lines at 1060 and 1330 nm were observed for Nd3+ in all the fluorophosphate glasses. From the emission spectra, emission characteristics were studied via optical band gains (σe×τR) and gain bandwidths (σe×Δλeff). Fairly large numerical values for peak emission cross-sections (σe) and branching ratios (β) for 4F3/2Æ4I11/2 transition of Nd3+ ion doped calcium fluorophosphate glass were observed. These results are rosy for NIR laser application at 1060 nm.
采用熔体淬火法制备了不同化学成分(59NH4H2PO4+15ZnO +15BaF2+10X+1·0NdF3 (X=LiF, NaF, CaF2, SrF2, AlF3))的掺钕氟磷酸盐(FP:Nd3+)玻璃。利用x射线衍射、FTIR、FT-Raman和31P, 27Al MAS NMR技术研究了它们的结构和光谱性质。利用FTIR和FT-Raman光谱鉴定了不同的结构基团。偏磷酸链的解聚合是通过Q2四面体位点的减少来描述的，从而形成了31P MAS NMR光谱研究显示的焦磷酸基团。利用吸收光谱和光致发光光谱对其光学性质进行了研究。利用吸收光谱估计Judd-Ofelt强度参数Ωλ (λ= 2,4和6)。计算了辐射参数，如跃迁概率(A)、辐射寿命(τR)、综合吸收截面(Σ)和分支比(βR)。在所有氟磷酸盐玻璃中均观察到Nd3+在1060和1330 nm处的两条发射线。从发射光谱出发，通过光带增益(σe×τR)和增益带宽(σe×Δλeff)研究了发射特性。掺Nd3+离子氟磷酸钙玻璃的4F3/2Æ4I11/2跃迁峰发射截面(σe)和支化比(β)均有较大的数值。这些结果对1060nm近红外激光器的应用具有积极意义。
{"title":"Spectral studies of Nd3+ doped different fluorophosphate glasses for their aptness in laser applications at 1060 nm","authors":"B. S. Narayana Devara, Y. C. Ratnakaram, M. Kumar","doi":"10.13036/17533562.64.2.12","DOIUrl":"https://doi.org/10.13036/17533562.64.2.12","url":null,"abstract":"Neodymium doped fluorophosphate (FP:Nd3+) glasses with different chemical compositions (59NH4H2PO4+15ZnO +15BaF2+10X+1·0NdF3 (X=LiF, NaF, CaF2, SrF2, AlF3)) were prepared by melt quenching. Their structures and spectroscopic properties were studied using x-ray diffraction, FTIR, FT-Raman and 31P, 27Al MAS NMR techniques. Various structural groups were identified using FTIR and FT-Raman spectra. The depolymerisation of metaphosphate chains are described by the decrease of Q2 tetrahedral sites allowing the formation of pyrophosphate groups revealed by 31P MAS NMR spectroscopic studies. Optical properties were studied using absorption and photoluminescence spectroscopy. Judd–Ofelt intensity parameters Ωλ (λ=2, 4 and 6) were estimated from absorption spectra. Radiative parameters such as transition probabilities (A), radiative lifetimes (τR), integrated absorption cross-sections (Σ) and branching ratios (βR) were calculated. Two emission lines at 1060 and 1330 nm were observed for Nd3+ in all the fluorophosphate glasses. From the emission spectra, emission characteristics were studied via optical band gains (σe×τR) and gain bandwidths (σe×Δλeff). Fairly large numerical values for peak emission cross-sections (σe) and branching ratios (β) for 4F3/2Æ4I11/2 transition of Nd3+ ion doped calcium fluorophosphate glass were observed. These results are rosy for NIR laser application at 1060 nm.","PeriodicalId":49696,"journal":{"name":"Physics and Chemistry of Glasses-European Journal of Glass Science and Technology Part B","volume":"56 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85017998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2023-04-01DOI: 10.13036/17533562.64.2.21
G. Marcucci, A. Scherillo, Ron I. Smith, D. Di Martino
We present a completely non-destructive study of the crystalline phases present in the vitreous matrix of ancient mosaic glass tesserae, based on the application of the time-of-flight neutron diffraction (ToF-ND) technique. In contrast, standard phase analysis techniques may involve a sample preparation step, which is not compatible with the requirement of damage prevention of archaeological artefacts. Moreover, superficial or spot investigation by standard methods may not provide a complete description of the samples, especially in the case of inhomogeneous materials such as mosaic glasses, whereas ToF-ND can investigate the whole glass composition at the centimetre scale. The present study aims to obtain a bulk characterization of the glasses in terms of their mineralogical phase composition. Six glass specimens of ancient mosaic glass tesserae, that had been previously analysed with other non-destructive techniques to obtain their chemical and phase composition, were investigated by ToF-ND. These tesserae come from archaeological excavations or mosaics under restoration from different archaeological sites and geographical areas (Italy, Greece, and Syria) and date from the 1st to the 11th century AD. Several crystalline phases based on Ca, Sb, Sn, Cu and Pb minerals were identified, confirming the mineralogical phases identified with Raman spectroscopy in previous analyses. In addition, several other phases were identified for five of the samples. It is concluded that ToF-ND is an extremely important complementary tool for non-destructive bulk investigations of mosaic glass tesserae, which can overcome the heterogeneity of this kind of archaeological material.
{"title":"Time-of-flight neutron diffraction applied to the identification of crystalline phases in historical mosaic glasses","authors":"G. Marcucci, A. Scherillo, Ron I. Smith, D. Di Martino","doi":"10.13036/17533562.64.2.21","DOIUrl":"https://doi.org/10.13036/17533562.64.2.21","url":null,"abstract":"We present a completely non-destructive study of the crystalline phases present in the vitreous matrix of ancient mosaic glass tesserae, based on the application of the time-of-flight neutron diffraction (ToF-ND) technique. In contrast, standard phase analysis techniques may involve a sample preparation step, which is not compatible with the requirement of damage prevention of archaeological artefacts. Moreover, superficial or spot investigation by standard methods may not provide a complete description of the samples, especially in the case of inhomogeneous materials such as mosaic glasses, whereas ToF-ND can investigate the whole glass composition at the centimetre scale. The present study aims to obtain a bulk characterization of the glasses in terms of their mineralogical phase composition. Six glass specimens of ancient mosaic glass tesserae, that had been previously analysed with other non-destructive techniques to obtain their chemical and phase composition, were investigated by ToF-ND. These tesserae come from archaeological excavations or mosaics under restoration from different archaeological sites and geographical areas (Italy, Greece, and Syria) and date from the 1st to the 11th century AD. Several crystalline phases based on Ca, Sb, Sn, Cu and Pb minerals were identified, confirming the mineralogical phases identified with Raman spectroscopy in previous analyses. In addition, several other phases were identified for five of the samples. It is concluded that ToF-ND is an extremely important complementary tool for non-destructive bulk investigations of mosaic glass tesserae, which can overcome the heterogeneity of this kind of archaeological material.","PeriodicalId":49696,"journal":{"name":"Physics and Chemistry of Glasses-European Journal of Glass Science and Technology Part B","volume":"80 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88998673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2023-04-01DOI: 10.13036/17533562.64.2.20
M. Prashant Kumar, A. Banagar, N. Nagaraja
A new series of (X) Na2O.(0·5−x)Fe2O3.(0·5)B2O3 of sodium and iron oxides doped borate glasses were synthesised by melt quenching. The bulk density, structural and temperature dependent electrical properties of these glasses have been investigated. The density decreased with increase in Na2O content up to Na2O=0·2 and increased thereafter. The FTIR studies indicated the presence of BO3 and BO4 groups in the network and also has shown presence of minimum NBOs at x=0·2. These results are attributed to the significant structural modifications taking place in the glass network at Na2O=0·20. The dc electrical conductivity decreased with increase in Na2O content up to Na2O=0·20 and increased for further addition of Na2O. The activation energy has increased up to 0·2 mol% of Na2O and decreased thereafter. Based on these results, it is established that at x=0·20, a changeover of dc conduction mechanism predominantly from polaronic to ionic is taking place. Mott’s SPH, Mott’s VRH and Greave’s VRH models have been used to explain the high and low temperature conductivities.
{"title":"Electrical transport studies in Na2O and Fe2O3 containing borate glasses","authors":"M. Prashant Kumar, A. Banagar, N. Nagaraja","doi":"10.13036/17533562.64.2.20","DOIUrl":"https://doi.org/10.13036/17533562.64.2.20","url":null,"abstract":"A new series of (X) Na2O.(0·5−x)Fe2O3.(0·5)B2O3 of sodium and iron oxides doped borate glasses were synthesised by melt quenching. The bulk density, structural and temperature dependent electrical properties of these glasses have been investigated. The density decreased with increase in Na2O content up to Na2O=0·2 and increased thereafter. The FTIR studies indicated the presence of BO3 and BO4 groups in the network and also has shown presence of minimum NBOs at x=0·2. These results are attributed to the significant structural modifications taking place in the glass network at Na2O=0·20. The dc electrical conductivity decreased with increase in Na2O content up to Na2O=0·20 and increased for further addition of Na2O. The activation energy has increased up to 0·2 mol% of Na2O and decreased thereafter. Based on these results, it is established that at x=0·20, a changeover of dc conduction mechanism predominantly from polaronic to ionic is taking place. Mott’s SPH, Mott’s VRH and Greave’s VRH models have been used to explain the high and low temperature conductivities.","PeriodicalId":49696,"journal":{"name":"Physics and Chemistry of Glasses-European Journal of Glass Science and Technology Part B","volume":"32 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87913592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2023-02-06DOI: 10.13036/17533562.64.1.26
Sofiane El Barkaoui, Abdelaziz El Abiad, I. Anasser, M. A. Harech, H. Aouad, M. Mesnaoui, T. Labbilta
In this work, manganese was suggested to improve the durability of 50P2O5–33·33K2O–(11·11−x/2) CaO−(5·56−x/2) MgO –xMnO glasses with 0≤x≤ 2 mol%. Indeed, its effect on the glass structure, thermal properties, physicochemical properties, and in particular, dissolution behaviours have been studied. The conventional melt-quenching technique was used to produce glasses at 1000°C and they were characterised by differential thermal analysis, density and molar volume measurements, x-ray diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy. Dissolution behaviours were tracked by measuring weight loss and pH. Molar volume measurements showed that phosphate glasses become more compact by incorporating MnO. Structural characterisation using Raman and infrared spectra proved that the glass network is composed mainly of metaphosphate chains. The dissolution results showed that incorporating manganese was an effective method to change the phosphate glasses’ chemical durability due to their ionic crosslinking between the nonbridging oxygen atoms of the phosphate chains, corresponding to the change in thermal properties (Tg, Tc and Tf).
在本研究中，锰可以提高50P2O5-33·33K2O -(11·11−x/2) CaO -(5·56−x/2) MgO - xmno玻璃的耐久性，其质量分数为0≤x≤2 mol%。事实上，它对玻璃结构、热性能、物理化学性能，特别是溶解行为的影响已经被研究过。采用传统的熔融淬火技术在1000℃下生产玻璃，并通过差热分析、密度和摩尔体积测量、x射线衍射、傅里叶变换红外光谱和拉曼光谱对其进行了表征。通过测量失重和ph值来跟踪溶解行为。摩尔体积测量表明，磷酸盐玻璃在加入MnO后变得更加致密。拉曼光谱和红外光谱的结构表征表明，该玻璃网络主要由偏磷酸盐链组成。溶解结果表明，加入锰是改变磷酸盐玻璃化学耐久性的有效方法，因为磷酸盐链的非桥接氧原子之间的离子交联，对应于热性能(Tg, Tc和Tf)的变化。
{"title":"Impact of MnO on the structural, physicochemical, and dissolution properties of phosphate-based glasses","authors":"Sofiane El Barkaoui, Abdelaziz El Abiad, I. Anasser, M. A. Harech, H. Aouad, M. Mesnaoui, T. Labbilta","doi":"10.13036/17533562.64.1.26","DOIUrl":"https://doi.org/10.13036/17533562.64.1.26","url":null,"abstract":"In this work, manganese was suggested to improve the durability of 50P2O5–33·33K2O–(11·11−x/2) CaO−(5·56−x/2) MgO –xMnO glasses with 0≤x≤ 2 mol%. Indeed, its effect on the glass structure, thermal properties, physicochemical properties, and in particular, dissolution behaviours have been studied. The conventional melt-quenching technique was used to produce glasses at 1000°C and they were characterised by differential thermal analysis, density and molar volume measurements, x-ray diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy. Dissolution behaviours were tracked by measuring weight loss and pH. Molar volume measurements showed that phosphate glasses become more compact by incorporating MnO. Structural characterisation using Raman and infrared spectra proved that the glass network is composed mainly of metaphosphate chains. The dissolution results showed that incorporating manganese was an effective method to change the phosphate glasses’ chemical durability due to their ionic crosslinking between the nonbridging oxygen atoms of the phosphate chains, corresponding to the change in thermal properties (Tg, Tc and Tf).","PeriodicalId":49696,"journal":{"name":"Physics and Chemistry of Glasses-European Journal of Glass Science and Technology Part B","volume":"4 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86181631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2023-02-06DOI: 10.13036/17533562.64.1.01
Arnab Ghosh, S. Ghosh, J. Mukherjee, R. Banerjee
Single walled carbon nanotubes (SWCNT) have been embedded as electrically conductive filler inside a borosilicate glass matrix to fabricate SWCNT–glass composites with enriched dielectric properties. The composite shows significantly increased dielectric constant (ε’) at room temperature which is 103 times higher than that of the base glass. Dielectric loss of the SWCNT–glass composite is also observed to be relatively low especially at higher frequencies. In correlation with the morphology, high dielectric constant of the composite is explained by the formation of microcapacitor networks of the carbon nanotubes and Maxwell–Wagner–Sillars polarization at nanotube/glass interface.
{"title":"Carbon nanotube–glass composite with high dielectric constant and low dielectric loss for energy storage device applications","authors":"Arnab Ghosh, S. Ghosh, J. Mukherjee, R. Banerjee","doi":"10.13036/17533562.64.1.01","DOIUrl":"https://doi.org/10.13036/17533562.64.1.01","url":null,"abstract":"Single walled carbon nanotubes (SWCNT) have been embedded as electrically conductive filler inside a borosilicate glass matrix to fabricate SWCNT–glass composites with enriched dielectric properties. The composite shows significantly increased dielectric constant (ε’) at room temperature which is 103 times higher than that of the base glass. Dielectric loss of the SWCNT–glass composite is also observed to be relatively low especially at higher frequencies. In correlation with the morphology, high dielectric constant of the composite is explained by the formation of microcapacitor networks of the carbon nanotubes and Maxwell–Wagner–Sillars polarization at nanotube/glass interface.","PeriodicalId":49696,"journal":{"name":"Physics and Chemistry of Glasses-European Journal of Glass Science and Technology Part B","volume":"357 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2023-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80163477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2022-12-11DOI: 10.13036/17533562.63.6.08
A. Wright, N. Vedishcheva
The presence of structural nanoheterogeneity means that sharp structural transitions at a well defined temperature or composition are an anathema to the vitreous state. Hence they should not be expected, but rather an extended transition, whose width is defined by the form and length scale of the relevant nanoheterogeneity. It should also be noted that all of the vitreous state transitions considered here, together with crystallisation at the melting point, are spatially non-uniform. This behaviour should be compared to sharp transitions that occur within the crystalline state, for example the displacive transition between α- and β-quartz, and those from a paramagnetic to a magnetically-ordered state. Such sharp transitions involve simultaneous co-operative movements across a large number identical unit cells, and hence cannot occur in the absence of a periodic structure. As a result, they are sensitive to disorder within individual unit cells, as may be seen from the case of cristobalite, where the presence of disorder reduces the αβ transition temperature, and in extremis inhibits the transition from β- to α-cristobalite.
{"title":"Letter to the Editor: Structural transitions of the vitreous state","authors":"A. Wright, N. Vedishcheva","doi":"10.13036/17533562.63.6.08","DOIUrl":"https://doi.org/10.13036/17533562.63.6.08","url":null,"abstract":"The presence of structural nanoheterogeneity means that sharp structural transitions at a well defined temperature or composition are an anathema to the vitreous state. Hence they should not be expected, but rather an extended transition, whose width is defined by the form and length scale of the relevant nanoheterogeneity. It should also be noted that all of the vitreous state transitions considered here, together with crystallisation at the melting point, are spatially non-uniform. This behaviour should be compared to sharp transitions that occur within the crystalline state, for example the displacive transition between α- and β-quartz, and those from a paramagnetic to a magnetically-ordered state. Such sharp transitions involve simultaneous co-operative movements across a large number identical unit cells, and hence cannot occur in the absence of a periodic structure. As a result, they are sensitive to disorder within individual unit cells, as may be seen from the case of cristobalite, where the presence of disorder reduces the αβ transition temperature, and in extremis inhibits the transition from β- to α-cristobalite.","PeriodicalId":49696,"journal":{"name":"Physics and Chemistry of Glasses-European Journal of Glass Science and Technology Part B","volume":"46 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73863478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2022-12-11DOI: 10.13036/17533562.63.6.13
U. Hoppe
The structural units of two types of conditional glass-forming oxides are irregular polyhedra whose distorted shapes result from intrinsic electronic causes. First example: The d0-transition metal cations Mo6+ form an amount of MoO6 in Ag molybdate glasses with the Mo6+ cation displaced towards an octahedral edge. Reverse Monte-Carlo results and comparisons with crystal structures corroborate the earlier diffraction interpretations of three distinct Mo−O distances in the MoO6 units. The post-transitional main group cation Te4+ forms high fractions of TeO5E units in phosphate glasses, where E denotes the lone-pair corner of the structural group. Instead of the regular TeO5E pyramids known for some related crystals, only irregular units are found in the glasses. The bond valences of their longest Te−O bonds are small, requiring the occurrence of three-fold coordinated oxygens.
{"title":"Network-forming oxides with non-centrosymmetric structural groups – diffraction results on molybdate and tellurite glasses","authors":"U. Hoppe","doi":"10.13036/17533562.63.6.13","DOIUrl":"https://doi.org/10.13036/17533562.63.6.13","url":null,"abstract":"The structural units of two types of conditional glass-forming oxides are irregular polyhedra whose distorted shapes result from intrinsic electronic causes. First example: The d0-transition metal cations Mo6+ form an amount of MoO6 in Ag molybdate glasses with the Mo6+ cation displaced towards an octahedral edge. Reverse Monte-Carlo results and comparisons with crystal structures corroborate the earlier diffraction interpretations of three distinct Mo−O distances in the MoO6 units. The post-transitional main group cation Te4+ forms high fractions of TeO5E units in phosphate glasses, where E denotes the lone-pair corner of the structural group. Instead of the regular TeO5E pyramids known for some related crystals, only irregular units are found in the glasses. The bond valences of their longest Te−O bonds are small, requiring the occurrence of three-fold coordinated oxygens.","PeriodicalId":49696,"journal":{"name":"Physics and Chemistry of Glasses-European Journal of Glass Science and Technology Part B","volume":"10 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78512749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 : 2022-08-29DOI: 10.13036/17533562.64.1.18
C. Ugwumadu, K. Nepal, R. Thapa, David Alan Drabold
This paper focuses on the structural, electronic, and vibrational features of amorphous graphite [R. Thapa et al, Phys. Rev. Lett., 2022, 128, 236402]. The structural order in amorphous graphite is discussed and compared with graphite and amorphous carbon. The electronic density of states and localization in these phases were analyzed. Spatial projection of charge densities in the π bands showed a high charge concentration on participating atoms in connecting hexagons. A vibrational density of states was computed and is potentially an experimentally testable fingerprint of the material. An analysis of the vibrational modes was carried out using the phase quotient, and the mode stretching character. The average thermal conductivity calculated for aG was 0·85 and 0·96 W/cmK at room temperature and 1000 K, respectively.
{"title":"Atomistic nature of amorphous graphite","authors":"C. Ugwumadu, K. Nepal, R. Thapa, David Alan Drabold","doi":"10.13036/17533562.64.1.18","DOIUrl":"https://doi.org/10.13036/17533562.64.1.18","url":null,"abstract":"This paper focuses on the structural, electronic, and vibrational features of amorphous graphite [R. Thapa et al, Phys. Rev. Lett., 2022, 128, 236402]. The structural order in amorphous graphite is discussed and compared with graphite and amorphous carbon. The electronic density of states and localization in these phases were analyzed. Spatial projection of charge densities in the π bands showed a high charge concentration on participating atoms in connecting hexagons. A vibrational density of states was computed and is potentially an experimentally testable fingerprint of the material. An analysis of the vibrational modes was carried out using the phase quotient, and the mode stretching character. The average thermal conductivity calculated for aG was 0·85 and 0·96 W/cmK at room temperature and 1000 K, respectively.","PeriodicalId":49696,"journal":{"name":"Physics and Chemistry of Glasses-European Journal of Glass Science and Technology Part B","volume":"13 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88444315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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