A transient 2D axisymmetric mathematical model that couples the pulse electromagnetic field with fluid flow and solidification was established by using the COMSOL Multiphysics software. The solidification behavior of Fe–0.2C–6Cu wt.% alloy during direct chill (DC) casting was first comparatively analyzed under conditions with and without the application of a pulsed magnetic field. Particular attention was paid to the evolution of melt flow, heat transfer, and solidification characteristics at various spatial locations. Subsequently, the coupled effects of pulsed electromagnetic parameters—including current intensity, frequency, and duty cycle—on the flow, thermal, solidification behavior, and mechanical response of the alloy were systematically investigated. The results demonstrate that optimized pulsed magnetic field (PMF) and differential-phase pulsed magnetic field (DPMF) conditions significantly enhance the Lorentz force, inducing strong and stable toroidal vortex structures. This in turn intensifies convective heat transfer and accelerates the solidification rate. Among the tested conditions, the combination of a 1200 A current and a frequency of 10 Hz yielded the most favorable electromagnetic response. Mechanical analyses further indicated that enhanced strain compatibility and stress redistribution capabilities were observed at critical interface regions under DPMF conditions, highlighting the potential of DPMF to tailor solidification microstructures and mitigate the development of residual stresses during DC casting.
{"title":"Transient simulation of multi-physical field evolution in Fe–0.2C–6Cu alloy under pulsed and differential-phase magnetic fields","authors":"Chongbo Li, Junting Zhang, Dongxia Kou, Zexiao Han, Kaihui Ma, Yuanji Xu","doi":"10.1016/j.jcrysgro.2025.128446","DOIUrl":"10.1016/j.jcrysgro.2025.128446","url":null,"abstract":"<div><div>A transient 2D axisymmetric mathematical model that couples the pulse electromagnetic field with fluid flow and solidification was established by using the COMSOL Multiphysics software. The solidification behavior of Fe–0.2C–6Cu wt.% alloy during direct chill (DC) casting was first comparatively analyzed under conditions with and without the application of a pulsed magnetic field. Particular attention was paid to the evolution of melt flow, heat transfer, and solidification characteristics at various spatial locations. Subsequently, the coupled effects of pulsed electromagnetic parameters—including current intensity, frequency, and duty cycle—on the flow, thermal, solidification behavior, and mechanical response of the alloy were systematically investigated. The results demonstrate that optimized pulsed magnetic field (PMF) and differential-phase pulsed magnetic field (DPMF) conditions significantly enhance the Lorentz force, inducing strong and stable toroidal vortex structures. This in turn intensifies convective heat transfer and accelerates the solidification rate. Among the tested conditions, the combination of a 1200 A current and a frequency of 10 Hz yielded the most favorable electromagnetic response. Mechanical analyses further indicated that enhanced strain compatibility and stress redistribution capabilities were observed at critical interface regions under DPMF conditions, highlighting the potential of DPMF to tailor solidification microstructures and mitigate the development of residual stresses during DC casting.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"676 ","pages":"Article 128446"},"PeriodicalIF":2.0,"publicationDate":"2025-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145682806","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 : 2025-11-25DOI: 10.1016/j.jcrysgro.2025.128445
Christiane Frank-Rotsch
{"title":"Report from the meetings of the International Organization for Crystal Growth governing bodies held during the ICCGE-21 Conference in Xi’an, China, August 03–08, 2025","authors":"Christiane Frank-Rotsch","doi":"10.1016/j.jcrysgro.2025.128445","DOIUrl":"10.1016/j.jcrysgro.2025.128445","url":null,"abstract":"","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"676 ","pages":"Article 128445"},"PeriodicalIF":2.0,"publicationDate":"2025-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145786843","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 : 2025-11-22DOI: 10.1016/j.jcrysgro.2025.128428
Architha Natarajan, Srinivasan Karuppannan
The crystallization behavior of metacetamol polymorphs from the melt was systematically investigated using a custom-designed Vertical Bridgman (VB) furnace. By varying the ampoule translation rate between 1.5 and 24 cm/min, corresponding to cooling rates of approximately 3.6 to 58.5 °C/min, distinct polymorphic outcomes were observed. Form I emerged predominantly at both low (3.6–7.2 °C/min) and high (13.5–58.5 °C/min) cooling rates, whereas the metastable form II was confined to a narrow intermediate cooling-rate window (7.3–13.4 °C/min). These findings underscore the critical influence of cooling rate on polymorph selection during melt crystallization. Powder X-ray diffraction (PXRD) confirmed the crystal systems and enabled refinement of lattice parameters, while differential scanning calorimetry (DSC) and thermogravimetric-differential thermal analysis (TG-DTA) provided insights into the thermal properties of the polymorphs. This work demonstrates a scalable, solvent-free approach to selectively obtain metacetamol polymorphs, offering valuable implications for controlled pharmaceutical manufacturing.
{"title":"Melt crystallization of metacetamol polymorphs using vertical Bridgman method","authors":"Architha Natarajan, Srinivasan Karuppannan","doi":"10.1016/j.jcrysgro.2025.128428","DOIUrl":"10.1016/j.jcrysgro.2025.128428","url":null,"abstract":"<div><div>The crystallization behavior of metacetamol polymorphs from the melt was systematically investigated using a custom-designed Vertical Bridgman (VB) furnace. By varying the ampoule translation rate between 1.5 and 24 cm/min, corresponding to cooling rates of approximately 3.6 to 58.5 °C/min, distinct polymorphic outcomes were observed. Form I emerged predominantly at both low (3.6–7.2 °C/min) and high (13.5–58.5 °C/min) cooling rates, whereas the metastable form II was confined to a narrow intermediate cooling-rate window (7.3–13.4 °C/min). These findings underscore the critical influence of cooling rate on polymorph selection during melt crystallization. Powder X-ray diffraction (PXRD) confirmed the crystal systems and enabled refinement of lattice parameters, while differential scanning calorimetry (DSC) and thermogravimetric-differential thermal analysis (TG-DTA) provided insights into the thermal properties of the polymorphs. This work demonstrates a scalable, solvent-free approach to selectively obtain metacetamol polymorphs, offering valuable implications for controlled pharmaceutical manufacturing.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"676 ","pages":"Article 128428"},"PeriodicalIF":2.0,"publicationDate":"2025-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145682804","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 : 2025-11-22DOI: 10.1016/j.jcrysgro.2025.128427
Ziyu Yang , Zihua Ma , Jianghai He , Chufeng Hou , Qi Liu , Shihao Xia , Kongli Ran , Qiang Wang , Yuefei Zhang , Fei Chen
This study utilizes Atomic Layer Deposition (ALD) technology, employing Trimethylgallium (TMG) and Ozone (O3) as precursors to fabricate Ga2O3 thin films. To enhance the crystallinity of the films, the effects of seed layers and annealing processes on the Ga2O3 thin films were investigated. High-quality β-Ga2O3 thin films were successfully grown on sapphire substrates. Experimental results indicate that directly depositing Ga2O3 on sapphire substrates did not yield satisfactory β-Ga2O3 films. To improve the crystallinity, a Ga2O3 seed layer was prepared on the sapphire substrate, and high-temperature annealing was employed to promote crystallization of the Ga2O3 seed layer, providing artificial nucleation sites for subsequent thin film deposition. The influence of the annealing temperature and seed layer thickness on the quality of the secondary Ga2O3 films was also studied. It was found that a seed layer with a thickness of 16.5 nm, followed by annealing at 1000 °C, resulted in Ga2O3 films with optimal crystallinity. After the deposition of the thin film, post-deposition annealing was performed to investigate the effects of annealing temperature on the structural and optical properties of the Ga2O3 films. The results show that with increasing annealing temperature, the optical band gap of the films enlarged, the proportion of high-valence gallium increased, and the crystallinity improved. Thus, it can be concluded that optimized annealing conditions lead to higher quality Ga2O3 films. The optical band gap of the Ga2O3 film treated with 30 min of annealing reached its maximum value of approximately 5.24 eV. Under a 5 V bias, the photocurrent was 1.9 × 10−4 A, the dark current was 4.9 × 10−7 A, and the photo-dark ratio was 388, which showed significant improvement compared to the as-deposited sample. At a 10 V bias, the device’s response time (τx) was 0.3 s, and its decay time (τd) was 0.28 s.
{"title":"The effect of annealing process and seed layer control on the crystallization characteristics and optoelectronic properties of β-Ga2O3 films fabricated by ALD","authors":"Ziyu Yang , Zihua Ma , Jianghai He , Chufeng Hou , Qi Liu , Shihao Xia , Kongli Ran , Qiang Wang , Yuefei Zhang , Fei Chen","doi":"10.1016/j.jcrysgro.2025.128427","DOIUrl":"10.1016/j.jcrysgro.2025.128427","url":null,"abstract":"<div><div>This study utilizes Atomic Layer Deposition (ALD) technology, employing Trimethylgallium (TMG) and Ozone (O<sub>3</sub>) as precursors to fabricate Ga<sub>2</sub>O<sub>3</sub> thin films. To enhance the crystallinity of the films, the effects of seed layers and annealing processes on the Ga<sub>2</sub>O<sub>3</sub> thin films were investigated. High-quality β-Ga<sub>2</sub>O<sub>3</sub> thin films were successfully grown on sapphire substrates. Experimental results indicate that directly depositing Ga<sub>2</sub>O<sub>3</sub> on sapphire substrates did not yield satisfactory β-Ga<sub>2</sub>O<sub>3</sub> films. To improve the crystallinity, a Ga<sub>2</sub>O<sub>3</sub> seed layer was prepared on the sapphire substrate, and high-temperature annealing was employed to promote crystallization of the Ga<sub>2</sub>O<sub>3</sub> seed layer, providing artificial nucleation sites for subsequent thin film deposition. The influence of the annealing temperature and seed layer thickness on the quality of the secondary Ga<sub>2</sub>O<sub>3</sub> films was also studied. It was found that a seed layer with a thickness of 16.5 nm, followed by annealing at 1000 °C, resulted in Ga<sub>2</sub>O<sub>3</sub> films with optimal crystallinity. After the deposition of the thin film, post-deposition annealing was performed to investigate the effects of annealing temperature on the structural and optical properties of the Ga<sub>2</sub>O<sub>3</sub> films. The results show that with increasing annealing temperature, the optical band gap of the films enlarged, the proportion of high-valence gallium increased, and the crystallinity improved. Thus, it can be concluded that optimized annealing conditions lead to higher quality Ga<sub>2</sub>O<sub>3</sub> films. The optical band gap of the Ga<sub>2</sub>O<sub>3</sub> film treated with 30 min of annealing reached its maximum value of approximately 5.24 eV. Under a 5 V bias, the photocurrent was 1.9 × 10<sup>−4</sup> A, the dark current was 4.9 × 10<sup>−7</sup> A, and the photo-dark ratio was 388, which showed significant improvement compared to the as-deposited sample. At a 10 V bias, the device’s response time (τ<sub>x</sub>) was 0.3 s, and its decay time (τd) was 0.28 s.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"675 ","pages":"Article 128427"},"PeriodicalIF":2.0,"publicationDate":"2025-11-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145616095","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 : 2025-11-21DOI: 10.1016/j.jcrysgro.2025.128426
Hannah Hall, Sunil Timilsina, Sneha Upadhyay, Tyler Erickson, Cherie D’Mello, David C. Ingram, Arthur R. Smith
Weyl semimetal thin films with excellent crystalline quality are of great interest for antiferromagnetic spintronics. MnSn is one Weyl semimetal with great properties and promise for exciting science and applications. It has proven very challenging, however, to grow MnSn thin films with smooth surfaces, negligible strain, and excellent crystallinity. In this work, we discuss the successful preparation of epitaxial MnSn (0001)-oriented thin films via molecular beam epitaxial growth on -plane wurtzite GaN which was grown by MBE on AlO (0001). We present the reflection high energy electron diffraction analysis along with x-ray diffraction in order to demonstrate the crystalline quality of the film, and we give atomic models to explain the epitaxial orientation relationships between the crystal lattices of the substrate, GaN layer, and MnSn layer. Importantly, we discuss the film lattice parameters as compared to expected values, demonstrating negligible strain both in-plane and out-of-plane. Atomic force microscopy reveals an epitaxial columnar growth mode characterized by flat-top-mesa islands, while scanning tunneling microscopy shows the atomically smooth surfaces of the mesa-top structures. Finally, Rutherford backscattering informs the stoichiometry of the film as well as the layer thicknesses.
{"title":"Epitaxial columnar growth of strain-free antiferromagnetic Weyl semimetal Mn3Sn on wurtzite c-plane GaN/Al2O3(0001)","authors":"Hannah Hall, Sunil Timilsina, Sneha Upadhyay, Tyler Erickson, Cherie D’Mello, David C. Ingram, Arthur R. Smith","doi":"10.1016/j.jcrysgro.2025.128426","DOIUrl":"10.1016/j.jcrysgro.2025.128426","url":null,"abstract":"<div><div>Weyl semimetal thin films with excellent crystalline quality are of great interest for antiferromagnetic spintronics. Mn<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>Sn is one Weyl semimetal with great properties and promise for exciting science and applications. It has proven very challenging, however, to grow Mn<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>Sn thin films with smooth surfaces, negligible strain, and excellent crystallinity. In this work, we discuss the successful preparation of epitaxial Mn<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>Sn (0001)-oriented thin films via molecular beam epitaxial growth on <span><math><mi>c</mi></math></span>-plane wurtzite GaN which was grown by MBE on Al<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span> (0001). We present the reflection high energy electron diffraction analysis along with x-ray diffraction in order to demonstrate the crystalline quality of the film, and we give atomic models to explain the epitaxial orientation relationships between the crystal lattices of the substrate, GaN layer, and Mn<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>Sn layer. Importantly, we discuss the film lattice parameters as compared to expected values, demonstrating negligible strain both <em>in-plane</em> and <em>out-of-plane</em>. Atomic force microscopy reveals an epitaxial columnar growth mode characterized by flat-top-mesa islands, while scanning tunneling microscopy shows the atomically smooth surfaces of the mesa-top structures. Finally, Rutherford backscattering informs the stoichiometry of the film as well as the layer thicknesses.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"676 ","pages":"Article 128426"},"PeriodicalIF":2.0,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145600639","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 : 2025-11-20DOI: 10.1016/j.jcrysgro.2025.128425
Gulnaz Gahramanova , Rasim Jabbarov , Oliver Rettig , Imamaddin Amiraslanov , Irada Mammadova , Ferdinand Scholz
This work investigates the role of directly synthesized multiwalled carbon nanotube (MWCNT) as an intermediate layer for the growth of gallium nitride (GaN) on c-plane sapphire. MWCNTs forests were grown on c-plane sapphire using aerosol-assisted chemical vapor deposition (A-CVD), and the structural and crystalline characteristics of these MWCNT templates were confirmed by Raman spectroscopy and powder X-ray diffraction (PXRD). Subsequently, GaN layers were grown via Metal-Organic Vapor Phase Epitaxy (MOVPE) on both bare c-sapphire and MWCNT/c-sapphire templates.
Structural and optical analyses (SEM, HRXRD, and low-temperature PL) reveal that GaN grown on MWCNTs is polycrystalline and exhibits reduced crystalline quality compared to GaN/sapphire, confirming a fundamentally different growth mode. Despite this, the hybrid GaN/MWCNT architecture exhibits significantly enhanced electrical conductivity. At 3 MHz, the AC conductivity of GaN/MWCNT/sapphire reaches ∼7 × 103 µS, compared to ∼4.5 × 102 µS for GaN/sapphire. Under DC bias, the current at 20 V increases from ∼10−8 A (GaN/sapphire) to the milliamp range (10−3 A) for GaN/MWCNT/sapphire. These results demonstrate that MWCNT forests do not serve as a replacement for high-quality epitaxial GaN but instead enable a non-conventional GaN growth platform—porous, conductive, and weakly bonded to the substrate—opening pathways for GaN architectures relevant to sensing, catalytic interfaces, UV detection, and future transferable/lift-off GaN films.
{"title":"Role of directly grown multiwalled carbon nanotube as intermediate layers for GaN on c-plane sapphire","authors":"Gulnaz Gahramanova , Rasim Jabbarov , Oliver Rettig , Imamaddin Amiraslanov , Irada Mammadova , Ferdinand Scholz","doi":"10.1016/j.jcrysgro.2025.128425","DOIUrl":"10.1016/j.jcrysgro.2025.128425","url":null,"abstract":"<div><div>This work investigates the role of directly synthesized multiwalled carbon nanotube (MWCNT) as an intermediate layer for the growth of gallium nitride (GaN) on c-plane sapphire. MWCNTs forests were grown on c-plane sapphire using aerosol-assisted chemical vapor deposition (A-CVD), and the structural and crystalline characteristics of these MWCNT templates were confirmed by Raman spectroscopy and powder X-ray diffraction (PXRD). Subsequently, GaN layers were grown via Metal-Organic Vapor Phase Epitaxy (MOVPE) on both bare c-sapphire and MWCNT/c-sapphire templates.</div><div>Structural and optical analyses (SEM, HRXRD, and low-temperature PL) reveal that GaN grown on MWCNTs is polycrystalline and exhibits reduced crystalline quality compared to GaN/sapphire, confirming a fundamentally different growth mode. Despite this, the hybrid GaN/MWCNT architecture exhibits significantly enhanced electrical conductivity. At 3 MHz, the AC conductivity of GaN/MWCNT/sapphire reaches ∼7 × 10<sup>3</sup> µS, compared to ∼4.5 × 10<sup>2</sup> µS for GaN/sapphire. Under DC bias, the current at 20 V increases from ∼10<sup>−8</sup> A (GaN/sapphire) to the milliamp range (10<sup>−3</sup> A) for GaN/MWCNT/sapphire. These results demonstrate that MWCNT forests do not serve as a replacement for high-quality epitaxial GaN but instead enable a non-conventional GaN growth platform—porous, conductive, and weakly bonded to the substrate—opening pathways for GaN architectures relevant to sensing, catalytic interfaces, UV detection, and future transferable/lift-off GaN films.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"675 ","pages":"Article 128425"},"PeriodicalIF":2.0,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145570926","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}
Gallium Antimonide (GaSb) proves to be a suitable substrate material in mid-infrared optoelectronic, spintronic and high speed electronic devices due to its lattice compatibility with the other compound semiconductors. Bandgap tuning, magnetic behaviour as well as tailoring the defects that directly impact the carrier mobility and conductivity can be done with doping transition metals. The present work involves growth of Fe doped GaSb by customized in-house horizontal “Thermo-Vertical Directional Solidification” (TVDS) apparatus. This compound semiconductor processing apparatus facilitates both the synthesis of the melt and the crystal growth process under precise thermal control of 1⁰C/min accuracy. Phase formation was confirmed by room temperature X-ray Diffraction (XRD) pattern which shows little lattice expansion with Fe doping at Ga site. Morphological study using Scanning Electron Microscopy (SEM) images reported average etch pit density of 2.1 × 105 cm−2 on the surface. The crystallite size from XRD and sub-grain size from SEM are nearly similar in dimension. Hall effect measurement results showed increase in mobility and carrier concentration while the resistivity value decreases. Similar changes in electrical parameters were further confirmed by the Dielectric Spectroscopy that give insights to different kinds of polarization mechanisms due to dopant-induced additional p-type carriers.
{"title":"Effect of Fe in structural and electrical properties in GaSb grown by TVDS technique","authors":"Gayatree Tripathy, Diana Pradhan, Sushanta Kumar Kamilla","doi":"10.1016/j.jcrysgro.2025.128423","DOIUrl":"10.1016/j.jcrysgro.2025.128423","url":null,"abstract":"<div><div>Gallium Antimonide (GaSb) proves to be a suitable substrate material in mid-infrared optoelectronic, spintronic and high speed electronic devices due to its lattice compatibility with the other compound semiconductors. Bandgap tuning, magnetic behaviour as well as tailoring the defects that directly impact the carrier mobility and conductivity can be done with doping transition metals. The present work involves growth of Fe doped GaSb by customized in-house horizontal “Thermo-Vertical Directional Solidification” (TVDS) apparatus. This compound semiconductor processing apparatus facilitates both the synthesis of the melt and the crystal growth process under precise thermal control of 1⁰C/min accuracy. Phase formation was confirmed by room temperature X-ray Diffraction (XRD) pattern which shows little lattice expansion with Fe doping at Ga site. Morphological study using Scanning Electron Microscopy (SEM) images reported average etch pit density of 2.1 × 10<sup>5</sup> cm<sup>−2</sup> on the surface. The crystallite size from XRD and sub-grain size from SEM are nearly similar in dimension. Hall effect measurement results showed increase in mobility and carrier concentration while the resistivity value decreases. Similar changes in electrical parameters were further confirmed by the Dielectric Spectroscopy that give insights to different kinds of polarization mechanisms due to dopant-induced additional <em>p</em>-type carriers.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"675 ","pages":"Article 128423"},"PeriodicalIF":2.0,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145570927","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 : 2025-11-19DOI: 10.1016/j.jcrysgro.2025.128422
Umar Bashir , Saud Bin Anooz , Martin Schmidbauer , Lukas M. Eng , Matthias Bickermann , Steffen Ganschow
The compositional homogeneity of nominally LiNb1−xTaxO3 (x = 0.45) single crystals is studied using micro-X-ray fluorescence and high-resolution X-ray diffraction. Highly homogeneous regions are reported with less than 1 % Ta variation over areas as large as 4 × 4 mm2 in z-cut specimens. To our knowledge, this represents the most detailed study of homogeneity in lithium niobate tantalate (LNT) solid solutions to date, establishing a quantitative benchmark for future studies. Spectroscopic ellipsometry shows a decreasing refractive index and blue-shift in optical absorption with increasing Ta content, while the dielectric response remains structurally consistent. These investigations establish a quantitative benchmark for selecting compositionally homogeneous LNT crystals suitable for applications such as second-harmonic generation, Raman spectroscopy, piezoresponse force microscopy, and domain wall conductivity.
{"title":"Structural and optical characterization of highly homogeneous lithium niobate tantalate single-crystal solid solutions","authors":"Umar Bashir , Saud Bin Anooz , Martin Schmidbauer , Lukas M. Eng , Matthias Bickermann , Steffen Ganschow","doi":"10.1016/j.jcrysgro.2025.128422","DOIUrl":"10.1016/j.jcrysgro.2025.128422","url":null,"abstract":"<div><div>The compositional homogeneity of nominally LiNb<sub>1−x</sub>Ta<sub>x</sub>O<sub>3</sub> (x = 0.45) single crystals is studied using micro-X-ray fluorescence and high-resolution X-ray diffraction. Highly homogeneous regions are reported with less than 1 % Ta variation over areas as large as 4 × 4 mm<sup>2</sup> in z-cut specimens. To our knowledge, this represents the most detailed study of homogeneity in lithium niobate tantalate (LNT) solid solutions to date, establishing a quantitative benchmark for future studies. Spectroscopic ellipsometry shows a decreasing refractive index and blue-shift in optical absorption with increasing Ta content, while the dielectric response remains structurally consistent. These investigations establish a quantitative benchmark for selecting compositionally homogeneous LNT crystals suitable for applications such as second-harmonic generation, Raman spectroscopy, piezoresponse force microscopy, and domain wall conductivity.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"676 ","pages":"Article 128422"},"PeriodicalIF":2.0,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145600614","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 : 2025-11-19DOI: 10.1016/j.jcrysgro.2025.128424
Mirza Nusrat Sweety , Shariful Islam
A novel crystallographic study has been conducted on a simplified synthesis of anatase TiO2 nanocrystals derived from a sol–gel process, utilizing TTIP as the precursor at a pH of 2, assisted by ultrasonic means. The Reitveld refinement analysis performed using whole powder pattern fitting (WPPF) confirmed the complete formation of the TiO2 anatase, verifying its tetragonal structure [α = β = γ = 90.0°; a = b = 3.7877 Å, c = 9.5090 Å]. Peak profiling indicated that the highest preferred orientation occurred along the (1 0 1) plane at 2θ = 25.357°, with a d-spacing of 0.35096 nm and an intensity of 6913 cps. The computed unit cell volume was 136.424 Å3, and additional measurements indicated a dislocation density of 0.00615 nm−2, lattice strain of 0.58 %, microstrain of 0.00815, crystallinity of 63.279 %, and a crystallinity index of 1.37, all suggesting lattice expansion and a significant capacity for defect tolerance, crucial for applications in electronics and catalysis. According to the Scherrer equation, the average crystallite size was determined to be 12.75 nm; using the Monshi-Scherrer model, it was calculated at 12.17 nm; the Williamson-Hall model yielded 27.57 nm; the LSLM of the Scherrer equation resulted in 13.57 nm; the Size-Strain plot model estimated it to be 6.48 nm; and the Halder-Wagner model provided a size of 7.20 nm. Energy dispersive spectroscopy (EDS) analysis confirmed the elemental purity, showing 34.89 % Ti and 65.11 % O, while scanning electron microscopy (SEM) revealed a uniform distribution of non-clumped nanoparticles. The UV study show cased that a blue-shifted intense absorption peak of TA (3.31 eV) compared to the bulk material reported in the literature (3.2 eV). The maximum photo-degradation efficiency under the dosage 30 mg, initial dye concentration 10 ppm, degradation time 60 min were found to be 98.8 %. By integrating a straightforward synthesis approach with comprehensive refinement, this detailed analysis of structural, optical and surface morphology along with photo-catalytic activity provides a reliable foundation for the production of pure anatase phase TiO2 nanocrystals.
{"title":"A reitveld refinement in WPPF analysis for crystallographic behavior study of nanocrystal anatase TiO2 synthesized by ultrasonic-assisted sol–gel method and its photocatalytic activity","authors":"Mirza Nusrat Sweety , Shariful Islam","doi":"10.1016/j.jcrysgro.2025.128424","DOIUrl":"10.1016/j.jcrysgro.2025.128424","url":null,"abstract":"<div><div>A novel crystallographic study has been conducted on a simplified synthesis of anatase TiO<sub>2</sub> nanocrystals derived from a sol–gel process, utilizing TTIP as the precursor at a pH of 2, assisted by ultrasonic means. The Reitveld refinement analysis performed using whole powder pattern fitting (WPPF) confirmed the complete formation of the TiO<sub>2</sub> anatase, verifying its tetragonal structure [α = β = γ = 90.0°; a = b = 3.7877 Å, c = 9.5090 Å]. Peak profiling indicated that the highest preferred orientation occurred along the (1<!--> <!-->0<!--> <!-->1) plane at 2θ = 25.357°, with a d-spacing of 0.35096 nm and an intensity of 6913 cps. The computed unit cell volume was 136.424 Å<sup>3</sup>, and additional measurements indicated a dislocation density of 0.00615 nm<sup>−2</sup>, lattice strain of 0.58 %, microstrain of 0.00815, crystallinity of 63.279 %, and a crystallinity index of 1.37, all suggesting lattice expansion and a significant capacity for defect tolerance, crucial for applications in electronics and catalysis. According to the Scherrer equation, the average crystallite size was determined to be 12.75 nm; using the Monshi-Scherrer model, it was calculated at 12.17 nm; the Williamson-Hall model yielded 27.57 nm; the LSLM of the Scherrer equation resulted in 13.57 nm; the Size-Strain plot model estimated it to be 6.48 nm; and the Halder-Wagner model provided a size of 7.20 nm. Energy dispersive spectroscopy (EDS) analysis confirmed the elemental purity, showing 34.89 % Ti and 65.11 % O, while scanning electron microscopy (SEM) revealed a uniform distribution of non-clumped nanoparticles. The UV study show cased that a blue-shifted intense absorption peak of T<sub>A</sub> (3.31 eV) compared to the bulk material reported in the literature (3.2 eV). The maximum photo-degradation efficiency under the dosage 30 mg, initial dye concentration 10 ppm, degradation time 60 min were found to be 98.8 %. By integrating a straightforward synthesis approach with comprehensive refinement, this detailed analysis of structural, optical and surface morphology along with photo-catalytic activity provides a reliable foundation for the production of pure anatase phase TiO<sub>2</sub> nanocrystals.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"675 ","pages":"Article 128424"},"PeriodicalIF":2.0,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145570925","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 : 2025-11-17DOI: 10.1016/j.jcrysgro.2025.128420
C.W. Lan
Step-flow dynamics during SiC solution growth critically shape surface morphology and defect formation, yet conventional models often average step densities or encounter front-tracking singularities, missing transient bunching and debunching. We introduce a quasi-discrete 2D/3D model that couples advection–diffusion transport with Gaussian-regularized Robin boundary conditions, representing macrosteps as localized, integral-matched sinks. Each macrostep is resolved by a few Gaussian-weighted nodes while solute transport is computed on a fine finite-element mesh, ensuring stability and mass conservation. Simulations reveal that parallel flow drives strong bunching, producing wide terraces with amplified supersaturation; bunched steps advance more slowly due to solute depletion, while high-supersaturation pockets accelerate leading steps and trigger debunching. Conversely, anti-parallel flow advects depletion upstream and preserves uniform step spacing, with no bunching across tested conditions. In three dimensions, parallel flow yields stripe coalescence, while anti-parallel flow stabilizes step trains. By quantifying terrace supersaturation’s link to polytype nucleation, this robust, efficient model offers a predictive tool for optimizing step morphology and minimizing defects in high-quality SiC crystal growth.
{"title":"Quasi-discrete modeling of step-flow dynamics: capturing bunching and debunching in sic solution growth","authors":"C.W. Lan","doi":"10.1016/j.jcrysgro.2025.128420","DOIUrl":"10.1016/j.jcrysgro.2025.128420","url":null,"abstract":"<div><div>Step-flow dynamics during SiC solution growth critically shape surface morphology and defect formation, yet conventional models often average step densities or encounter front-tracking singularities, missing transient bunching and debunching. We introduce a quasi-discrete 2D/3D model that couples advection–diffusion transport with Gaussian-regularized Robin boundary conditions, representing macrosteps as localized, integral-matched sinks. Each macrostep is resolved by a few Gaussian-weighted nodes while solute transport is computed on a fine finite-element mesh, ensuring stability and mass conservation. Simulations reveal that parallel flow drives strong bunching, producing wide terraces with amplified supersaturation; bunched steps advance more slowly due to solute depletion, while high-supersaturation pockets accelerate leading steps and trigger debunching. Conversely, anti-parallel flow advects depletion upstream and preserves uniform step spacing, with no bunching across tested conditions. In three dimensions, parallel flow yields stripe coalescence, while anti-parallel flow stabilizes step trains. By quantifying terrace supersaturation’s link to polytype nucleation, this robust, efficient model offers a predictive tool for optimizing step morphology and minimizing defects in high-quality SiC crystal growth.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"675 ","pages":"Article 128420"},"PeriodicalIF":2.0,"publicationDate":"2025-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145532754","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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