K. Bharathi, K. Chandra Babu Naidu, D. Baba Basha, Madunuri Chandrasekhar, L. Siva Sankara Reddy
{"title":"Dielectric and Thermal Behavior of Al-Doped Cobalt Titanate Nanoparticles","authors":"K. Bharathi, K. Chandra Babu Naidu, D. Baba Basha, Madunuri Chandrasekhar, L. Siva Sankara Reddy","doi":"10.1002/crat.202400183","DOIUrl":"https://doi.org/10.1002/crat.202400183","url":null,"abstract":"<p>The Al<i><sub>x</sub></i>Co<sub>1-</sub><i><sub>x</sub></i>TiO<sub>3+</sub><i><sub>δ</sub></i> (<i>x</i> = 0.2, 0.4, 0.6 & 0.8) (ACTO) nanoparticles are synthesized via hydrothermal method at low operating temperature of 423 K/8 h. The diiffraction patterns confirm the tetragonal phases of ACTO along with the secondary phases (*Co<sub>3</sub>O<sub>4</sub>). The morphology shows the homogeneous distribution of nanoparticles. In addition, for <i>x</i> = 0.2–0.4, <i>a</i> = b & <i>c</i> values are found to be decreasing from 0.3776 to 0.3771 nm & 0.8887–0.8878 nm, respectively, while for <i>x</i> = 0.6–0.8, the same values are found to be decreasing from 0.3780 to 0.3778 nm & 0.8881–0.8879 nm, respectively. The M–H curves provide the pure paramagnetic nature for <i>x</i> = 0.6 & 0.8 while the weak ferromagnetic nature for <i>x</i> = 0.2 & 0.4. At 8 MHz, the <i>ɛ</i>′ value of <i>x</i> = 0.2 (high cobalt content) shows the stabilized <i>ɛ</i>′ of ≈32.5 and the <i>ɛ</i>″ values of ACTO are changing from ≈1.6–10.6. Therefore, the <i>x</i> = 0.2 shows the high <i>ɛ</i>′ & <i>ɛ</i>″ suitable for high frequency dielectric absorber applications. The exponent “n” values determined using power law fit are noted to be increasing from 0.512 to 0.852 for <i>x</i> = 0.2–0.6 while the same is decreased to 0.664 for <i>x</i> = 0.8. All the “n” values are less than one and shows that the polaron hopping is slower than site relaxation. The mass loss, decomposition of various ingredient species, and other transition temperatures are evaluated by thermal study.</p>","PeriodicalId":48935,"journal":{"name":"Crystal Research and Technology","volume":"60 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143612423","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}
{"title":"Crystallization of α and β Polymorphs of Para Aminobenzoic Acid from Mixed Solvents by Slow Evaporation Method","authors":"Ansu Mathew, Madhumitha Madhesh, Srinivasan Karuppannan","doi":"10.1002/crat.202400216","DOIUrl":"https://doi.org/10.1002/crat.202400216","url":null,"abstract":"<p>Para aminobenzoic acid (p-ABA), a well-known pharmaceutical material with a challenging polymorphic nature, is chosen for study in this paper. The material has four reported polymorphs, containing two solution forms (α and β), a vapor form, and a high-pressure form. The solution-grown forms α and β are experimentally grown using mixed solvents of water and isopropyl alcohol with nine different mixing compositions at temperatures of 298, 303, and 308 K. The solubility of the commercially available p-ABA is calculated gravimetrically, and the polymorphic crystals are grown using the slow solvent evaporation method for all the mixing ratios at different temperatures. A ternary diagram constructed on the solubility of p-ABA in mixed solvents gives an insight into the nucleation nature of two polymorphs. To understand the nature of nucleation and growth of two forms of p-ABA, an in situ microscopic study is carried out, and the grown crystals are characterized using powder X-ray diffraction analysis and differential scanning calorimetry. This also confirmed that the grown crystals are two solutions grown polymorphs of para aminobenzoic acid, both belonging to monoclinic systems with P2<sub>1</sub>/n space group.</p>","PeriodicalId":48935,"journal":{"name":"Crystal Research and Technology","volume":"60 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143362922","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}
{"title":"Bulk Growth, Thermal, and Polarized Spectral Characters of Nd3+-Doped Ca3(BO3)2 Single Crystals","authors":"Pingzhang Yu, Hongwei Qi, Yanqing Liu, Fapeng Yu, Zhengping Wang, Yangyang Dang","doi":"10.1002/crat.202400230","DOIUrl":"https://doi.org/10.1002/crat.202400230","url":null,"abstract":"<p>The growth, ion concentrations, powder X-ray diffraction, thermal properties, and optical spectroscopy of Nd<sup>3</sup>⁺-doped Ca₃(BO₃)₂ single crystals are investigated. The Nd<sup>3+</sup>-doped Ca₃(BO₃)₂ single crystals with 1.97 at.% Nd<sup>3</sup>⁺ are successfully grown using the Czochralski (Cz) technique. To address the chemical valence imbalance between Nd<sup>3</sup>⁺ and Ca<sup>2</sup>⁺ in the Ca₃(BO₃)₂ crystals, the Na⁺ ions are introduced. The concentrations of Nd<sup>3</sup>⁺ and Na⁺ ions in the as-grown crystals are measured using inductively coupled plasma atomic emission spectroscopy (ICP-AES), yielding concentrations of 1.97 at% (N<sub>0</sub> = 1.55 × 10<sup>20</sup> cm<sup>−3</sup>), 1.94 at% (N<sub>0</sub> = 1.52 × 10<sup>20</sup> cm<sup>−3</sup>), respectively. The thermal behavior of the Nd<sup>3</sup>⁺-doped Ca<sub>3</sub>(BO<sub>3</sub>)<sub>2</sub> crystals, including thermal expansion coefficients, specific heat, and thermogravimetric and differential thermal analysis (TG-DTA), is systematically investigated. At room temperature, the polarized absorption spectra, polarized fluorescence spectra, and fluorescence decay lifetimes are measured. Spectral parameters, including polarized absorption and stimulated emission cross-sections, intensity parameters, transition probabilities, radiative lifetime, and branching ratios are determined using the Judd-Ofelt (J-O) theory. The results indicate that Nd<sup>3+</sup>-doped Ca<sub>3</sub>(BO<sub>3</sub>)<sub>2</sub> crystals are promising materials for near-infrared lasers, offering advantages such as rapid growth, large size, high specific heat, strong emission, and environmental stability.</p>","PeriodicalId":48935,"journal":{"name":"Crystal Research and Technology","volume":"60 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143362920","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}
{"title":"Effect of Voltage on Two-Step Micro-Arc Oxide Film of Mg-13Gd-4Y-2Zn-0.5Zr Alloy","authors":"Dalong Li, Wei Chen, ChangWei Li, Xin Jing, Kun Sun, Jiaqing Fan, Huagui Huang","doi":"10.1002/crat.202400214","DOIUrl":"https://doi.org/10.1002/crat.202400214","url":null,"abstract":"<p>Rare earth alloying is one of the effective ways to improve the performance of magnesium alloys, but strong galvanic corrosion occurs when rare earth magnesium alloys meet corrosive substances. To improve the corrosion resistance of rare earth magnesium alloys, this article takes Mg-13Gd-4Y-2Zn-0.5Zr rare earth magnesium alloy as the research object. First, a one-step micro arc oxidation process is used to obtain the film layer. The experiment shows that when the chemical composition and concentration of the electrolyte are constant, changing the voltage parameter of the one-step micro arc oxidation alone cannot prepare a thick, dense, and corrosion-resistant micro arc oxidation film layer, which cannot meet the practical application needs of rare earth magnesium alloys. Then, the one-step micro arc oxidation film layer is used as the substrate sample. By changing the voltage parameters, the sample is subjected to a second micro arc oxidation treatment to prepare a two-step micro arc oxidation film layer. In the study, it is found that the two-step microarc oxidation process increased the thickness of the film layer, which has good densification and corrosion resistance at a voltage of 452.5 V, improving the corrosion resistance of the film layer.</p>","PeriodicalId":48935,"journal":{"name":"Crystal Research and Technology","volume":"60 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143363018","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}
M. Suganya, P. Vijayakumar, V. Sivasubramanian, K. Ganesan, R.M. Sarguna, Amirdha Sher Gill, S. Ganesamoorthy
{"title":"Growth and Inelastic Light Scattering Studies on Sr2Nb2O7 Single Crystal","authors":"M. Suganya, P. Vijayakumar, V. Sivasubramanian, K. Ganesan, R.M. Sarguna, Amirdha Sher Gill, S. Ganesamoorthy","doi":"10.1002/crat.202400010","DOIUrl":"https://doi.org/10.1002/crat.202400010","url":null,"abstract":"<p>A crack-free and high structural quality Sr<sub>2</sub>Nb<sub>2</sub>O<sub>7</sub> single crystals are grown by the optical float zone method using optimized growth parameters. The Laue pattern confirms the single crystalline nature of the grown crystal. Temperature-dependent Raman and Brillouin light scattering studies reveal a significant shift in phonon modes across normal to incommensurate phase transition (T<sub>n-in</sub>) which occurs ≈488 K. In the temperature range from 900 down to 500 K, two optical phonon modes ≈63 (B1 mode) and 54 cm<sup>−1</sup> (A1 mode) are observed. The frequency of A1 mode strongly decreases with an increase in temperature above the T<sub>n-in</sub> while the frequency of this mode almost remains constant below the T<sub>n-in</sub>. In contrast, the frequency of B1 phonon mode is found to increase with temperature in the range of 500–900 K but it does not display a significant shift below the phase transition temperature. In addition, in the in-commensurate phase (T< 488 K), a new optical phonon mode (M1) at ≈35 cm<sup>−1</sup> also begins to appear and exhibits strong stiffening behavior with an increase in temperature in the range of 300–488 K. Moreover, the anomalous behavior of the acoustic phonon across T<sub>n-in</sub> are further probed using Brilliouin scattering. Longitudinal acoustic phonon mode at 41 GHz exhibits a strong change in slope near T<sub>n-in.</sub> In addition, the transverse acoustic modes at 28.6 and 22.4 GHz also exhibit strong anomalies with minimum frequency near T<sub>n-in</sub>. The inelastic light scattering studies provide valuable information on the phase transition.</p>","PeriodicalId":48935,"journal":{"name":"Crystal Research and Technology","volume":"60 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143113347","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}
{"title":"Issue Information: Crystal Research and Technology 12'2024","authors":"","doi":"10.1002/crat.202470045","DOIUrl":"https://doi.org/10.1002/crat.202470045","url":null,"abstract":"","PeriodicalId":48935,"journal":{"name":"Crystal Research and Technology","volume":"59 12","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/crat.202470045","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142860620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Design and Characterization of Se/Nb2O5 Interfaces as High Infrared- Absorbers and High Frequency Band Filters","authors":"A. F. Qasrawi, Rana B Daragme","doi":"10.1002/crat.202400194","DOIUrl":"https://doi.org/10.1002/crat.202400194","url":null,"abstract":"<p>Herein a new class of optoelectronic devices beneficial for infrared light absorption and high-frequency application in the terahertz frequency domain are designed and fabricated. The devices are formed by coating a highly transparent thin layer of Nb<sub>2</sub>O<sub>5</sub> onto a selenium-thin film to form Se/Nb<sub>2</sub>O<sub>5</sub> (SNO) optical interfaces. Although coating of Nb<sub>2</sub>O<sub>5</sub> nanosheets decreased the crystallite sizes and increased the strain and defect concentration in the hexagonal structured Se films, they successfully increased the light absorption by ≈148% in the infrared range of light. A blueshift in the energy band gap of Se from 2.02 to 2.30 eV is observed. The coating of the Nb<sub>2</sub>O<sub>5</sub> onto Se suppressed the free carrier absorption in Se and Nb<sub>2</sub>O<sub>5</sub>. As dielectric active layers, SNO interfaces showed a major resonance dielectric peak centered at 1.67 eV. The optical conductivity and terahertz cutoff frequency analyses which are handled using the Drude-Lorentz approach revealed the highest drift mobility and free carrier concentration of 17.17 cm<sup>2</sup> Vs<sup>−1</sup> and 5.0 <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>×</mo>\u0000 <mspace></mspace>\u0000 <msup>\u0000 <mn>10</mn>\u0000 <mn>17</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation>$ times {{10}^{17}}$</annotation>\u0000 </semantics></math> cm<sup>−3</sup> when an oscillator of energy of 1.75 eV is activated. In addition, the terahertz cutoff frequency spectra which varied in the range of 4.0–131 THz showed the suitability of the SNO devices for terahertz technology and other optoelectronics.</p>","PeriodicalId":48935,"journal":{"name":"Crystal Research and Technology","volume":"60 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143112243","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}
P.S Sankara Rama Krishnan, Joseph V Vas, Soumya Ranjan Mishra, Xuesong Xu, Karl Peter Davidson, Shakti P. Padhy, Martial Duchamp, R. V Ramanujan
{"title":"In Situ Operando Investigations of the Thermal Instability Mechanisms of a Deformed Ti-48Al Alloy","authors":"P.S Sankara Rama Krishnan, Joseph V Vas, Soumya Ranjan Mishra, Xuesong Xu, Karl Peter Davidson, Shakti P. Padhy, Martial Duchamp, R. V Ramanujan","doi":"10.1002/crat.202400177","DOIUrl":"https://doi.org/10.1002/crat.202400177","url":null,"abstract":"<p>TiAl based alloys are currently deployed in extreme service environments, such as jet engine turbine blades. The microstructure of these alloys is a two-phase lamellar structure, comprising of the majority γ-TiAl and the minority α<sub>2</sub>-Ti<sub>3</sub>Al phases. Understanding the microstructural evolution at high stresses and elevated temperatures is a key requirement to develop the next generation of these alloys. In situ hot stage TEM studies are reported of the mechanisms of lamellar instability and changes in phase fraction of both cold worked and undeformed Ti-48Al alloys. The effect of cold working on the kinetics of this instability has also been determined. Cross-sectional TEM samples are prepared on custom designed MEMS chips and in situ heating studies carried out. These results show that neck formation, break-up of lamellae, and spheroidization are the dominant mechanisms of microstructural instability. An increase in γ-TiAl phase content is also observed. The strain energy present in the α<sub>2</sub> and γ lamellae in cold worked samples results in microstructural instabilities occurring at lower temperatures in cold worked samples. These findings can be used to design new alloys with improved high temperature stability.</p>","PeriodicalId":48935,"journal":{"name":"Crystal Research and Technology","volume":"60 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143112533","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}
{"title":"Crystal Structures of Highly Electron-Accepting Naphtho[1,2-c:5,6-c]bis[1,2,5]Chalcogendiazole","authors":"Saki Tanaka, Takumi Matsuo, Shotaro Hayashi","doi":"10.1002/crat.202400204","DOIUrl":"https://doi.org/10.1002/crat.202400204","url":null,"abstract":"<p>Naphtho[1,2-c:5,6-c]bis[1,2,5]chalcogendiazole is an important building block for organic devices due to its highly electron-accepting properties. However, despite being an effective unit of low band gap organic semiconductors, fewer studies have been conducted on analyzing such units to understand their crystal structure. Here the crystal structure analysis of naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazole, naphtho[1,2-c:5,6-c]bis[1,2,5]oxadiazole is reported, and these brominated motifs. Crystal structures of naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazoles and its brominated compound show that the molecules form coplanar structures through N···S contacts, resulting in parallel face-to-face packing and π-π stacking. Double N···S contacts are found as a priority in such compounds. On the other hand, naphtho[1,2-c:5,6-c]bis[1,2,5]oxadiazoles gave N···H─C networks with π-π stacking. These differences will probably induce the difference in the crystal structure of the naphtho[1,2-c:5,6-c]bis[1,2,5]chalcogendiazole-based extended π-systems. Brominated one exhibits polymorphs, which works N···Br contacts or Br···Br contacts based on the interaction of the σ-hole of bromide. These investigations can be applied to the order-made synthesis of self-assembled soft matter and functional molecular crystals.</p>","PeriodicalId":48935,"journal":{"name":"Crystal Research and Technology","volume":"60 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143112244","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}
{"title":"Investigating the Influence of Pore Wall–Water Interactions on Proton Conductivity within Metal-Organic Nanotubes Using Electrochemical Impedance Spectroscopy","authors":"Tiron H.L. Jahinge, Tori Z. Forbes","doi":"10.1002/crat.202400181","DOIUrl":"https://doi.org/10.1002/crat.202400181","url":null,"abstract":"<p>Water-mediated proton conductivity in nanoporous materials is influenced by channel water ordering and the hydrophobicity/hydrophilicity of interior walls, making metal-organic nanotubes (MONTs) useful systems for exploring these relationships due to their high crystallinity and tunable hydrophobicity. In the current study, electrochemical impedance spectroscopy is utilized to explore the proton conductivity on two metal organic nanotubes (UMONT and Cu-LaMONT) with weak hydrophobic behavior that possess extended water networks within the 1-D channels. Measurements performed at 95% RH and 20 °C indicate values of 1.63 × 10<sup>−4</sup> S cm<sup>−1</sup> for UMONT and 3.80 × 10<sup>−4</sup> S cm<sup>−1</sup> for Cu-LaMONT, which is lower than values for walls with acidic, hydrophilic functional groups or nanotubular materials with strictly hydrophobic behavior. Proton conductivity decreases sharply with lower humidity, with Cu-LaMONT being more sensitive to humidity changes. At low temperatures, UMONT outperforms LaMONT due to its well-established hydrogen bonding network and hydrophobic interior. The anisotropic nature of proton conduction is also confirmed through pelletized powder sample analysis, emphasizing that the conductivity occurs through the water networks located within the 1-D MONT channels. These findings emphasize the importance of understanding water–pore interactions and the resulting proton conductivity mechanisms to understand complex systems and design advanced materials.</p>","PeriodicalId":48935,"journal":{"name":"Crystal Research and Technology","volume":"60 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/crat.202400181","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143120531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}