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Journal of Applied Crystallography最新文献

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The effects of low boron incorporation on the structural and optical properties of BxGa1−xN/SiC epitaxial layers 低硼掺杂对BxGa1−xN/SiC外延层结构和光学性能的影响
IF 5.2 3区 材料科学
Journal of Applied Crystallography Pub Date : 2024-11-04 DOI: 10.1107/S1600576724009579
Cosmin Romanitan, Juras Mickevičius, Florin Comanescu, Raluca Gavrila, Marius Stoian, Pericle Varasteanu, Arunas Kadys, Tadas Malinauskas, Emil-Mihai Pavelescu
{"title":"The effects of low boron incorporation on the structural and optical properties of BxGa1−xN/SiC epitaxial layers","authors":"Cosmin Romanitan,&nbsp;Juras Mickevičius,&nbsp;Florin Comanescu,&nbsp;Raluca Gavrila,&nbsp;Marius Stoian,&nbsp;Pericle Varasteanu,&nbsp;Arunas Kadys,&nbsp;Tadas Malinauskas,&nbsp;Emil-Mihai Pavelescu","doi":"10.1107/S1600576724009579","DOIUrl":"https://doi.org/10.1107/S1600576724009579","url":null,"abstract":"<p>BGaN epilayers with boron contents up to 5.6% were grown on SiC substrates by metal–organic chemical vapor deposition. The effects of boron incorporation on the structural and optical properties were studied by high-resolution X-ray diffraction (XRD), atomic force microscopy (AFM), Raman spectroscopy and photoluminescence (PL) spectroscopy. XRD reciprocal-space maps around the symmetric 0002 and asymmetric reflections allowed evaluation of the lattice constants and lattice mismatch with respect to the underlying substrate. XRD rocking curves and AFM measurements indicated the mosaic microstructure of the epilayer. The impact of boron content on crystallite size, tilt and twist is evaluated and the correlation with threading dislocation density is discussed. The deterioration of optical properties with increasing boron content was assessed by Raman and PL spectroscopy.</p>","PeriodicalId":48737,"journal":{"name":"Journal of Applied Crystallography","volume":"57 6","pages":"1815-1822"},"PeriodicalIF":5.2,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142764347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
IF 5.2 3区 材料科学
Journal of Applied Crystallography Pub Date : 2024-11-04
{"title":"","authors":"","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":48737,"journal":{"name":"Journal of Applied Crystallography","volume":"57 6","pages":"1984-1995"},"PeriodicalIF":5.2,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142764349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Grazing-incidence small-angle neutron scattering at high pressure (HP-GISANS): a soft matter feasibility study on grafted brush films 高压掠入射小角中子散射（HP-GISANS）：接枝电刷膜软物质可行性研究
IF 5.2 3区 材料科学
Journal of Applied Crystallography Pub Date : 2024-11-04 DOI: 10.1107/S1600576724009130
Apostolos Vagias, Theodore Manouras, Andreas Buchner, Philipp Gutfreund, Lionel Porcar, Mark Jacques, Leonardo Chiappisi, David P. Kosbahn, Marcell Wolf, Laura Guasco, Reiner Dahint, Maria Vamvakaki, Peter Müller-Buschbaum
{"title":"Grazing-incidence small-angle neutron scattering at high pressure (HP-GISANS): a soft matter feasibility study on grafted brush films","authors":"Apostolos Vagias,&nbsp;Theodore Manouras,&nbsp;Andreas Buchner,&nbsp;Philipp Gutfreund,&nbsp;Lionel Porcar,&nbsp;Mark Jacques,&nbsp;Leonardo Chiappisi,&nbsp;David P. Kosbahn,&nbsp;Marcell Wolf,&nbsp;Laura Guasco,&nbsp;Reiner Dahint,&nbsp;Maria Vamvakaki,&nbsp;Peter Müller-Buschbaum","doi":"10.1107/S1600576724009130","DOIUrl":"https://doi.org/10.1107/S1600576724009130","url":null,"abstract":"<p>Grazing-incidence small-angle neutron scattering (GISANS) under pressure (HP-GISANS) at the solid (Si)–liquid (D<sub>2</sub>O) interface is demonstrated for the pressure-induced lateral morphological characterization of the nanostructure in thin (&lt;100 nm) soft matter films. We demonstrate feasibility by investigating a hydrophobic {poly[(2,2,3,3,4,4,5,5-octafluoro)pentyl methacrylate]} (POFPMA)–hydrophilic {poly[2-(dimethylamino)ethyl methacrylate]} (PDMAEMA) brush mixture of strong incompatibility between the homopolymers, anchored on Si, at <i>T</i> = 45°C for two pressures, <i>P</i> = 1 bar and <i>P</i> = 800 bar. Our GISANS results reveal nanostructural rearrangements with increasing <i>P</i>, underlining <i>P</i>-induced effects in tethered polymer brush layers swollen with bulk solvent.</p>","PeriodicalId":48737,"journal":{"name":"Journal of Applied Crystallography","volume":"57 6","pages":"1978-1983"},"PeriodicalIF":5.2,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142764348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The smearing function for a multi-slit very small angle neutron scattering instrument 多缝极小角中子散射仪的涂抹函数
IF 5.2 3区 材料科学
Journal of Applied Crystallography Pub Date : 2024-10-29 DOI: 10.1107/S1600576724009014
Zehua Han, Changli Ma, Hong Zhu, Tengfei Cui, Taisen Zuo, He Cheng
{"title":"The smearing function for a multi-slit very small angle neutron scattering instrument","authors":"Zehua Han,&nbsp;Changli Ma,&nbsp;Hong Zhu,&nbsp;Tengfei Cui,&nbsp;Taisen Zuo,&nbsp;He Cheng","doi":"10.1107/S1600576724009014","DOIUrl":"https://doi.org/10.1107/S1600576724009014","url":null,"abstract":"<p>Besides traditional pinhole geometry, the multi-slit very small angle neutron scattering instrument (MS-VSANS) at the China Spallation Neutron Source also utilizes a multi-slit collimation system to focus neutrons. Using the special focusing structures, the minimum scattering vector magnitude (<i>q)</i> can reach 0.00028 Å<sup>−1</sup>. The special structures also lead to a significantly different smearing function. By comparing the results of theoretical calculations with experimental data, we have validated the feasibility of a smearing method based on a mature theory for slit smearing. We use the weight-averaged intensity of neutron wavelength as a representative to evaluate the effect from a broad wavelength distribution, concentrating on the effect from the geometry of the multi-slit structures and the detector. The consistency of the theoretical calculation of the smearing function with experimental VSANS scattering profiles for a series of polystyrene standards of different diameters proves the feasibility of the smearing method. This marks the inaugural use of real experimental data from an instrument employing a multi-slit collimation system.</p>","PeriodicalId":48737,"journal":{"name":"Journal of Applied Crystallography","volume":"57 6","pages":"1772-1779"},"PeriodicalIF":5.2,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142764491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
IF 5.2 3区 材料科学
Journal of Applied Crystallography Pub Date : 2024-10-29
{"title":"","authors":"","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":48737,"journal":{"name":"Journal of Applied Crystallography","volume":"57 6","pages":"1780-1788"},"PeriodicalIF":5.2,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142764492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
IF 5.2 3区 材料科学
Journal of Applied Crystallography Pub Date : 2024-10-29
{"title":"","authors":"","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":48737,"journal":{"name":"Journal of Applied Crystallography","volume":"57 6","pages":"2043-2047"},"PeriodicalIF":5.2,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142763939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
IF 5.2 3区 材料科学
Journal of Applied Crystallography Pub Date : 2024-10-29
{"title":"","authors":"","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":48737,"journal":{"name":"Journal of Applied Crystallography","volume":"57 6","pages":"1789-1799"},"PeriodicalIF":5.2,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142764493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Multi-scale and time-resolved structure analysis of relaxor ferroelectric crystals under an electric field 电场作用下弛豫铁电晶体的多尺度和时间分辨结构分析
IF 5.2 3区 材料科学
Journal of Applied Crystallography Pub Date : 2024-10-29 DOI: 10.1107/S1600576724009440
Shinobu Aoyagi
{"title":"Multi-scale and time-resolved structure analysis of relaxor ferroelectric crystals under an electric field","authors":"Shinobu Aoyagi","doi":"10.1107/S1600576724009440","DOIUrl":"https://doi.org/10.1107/S1600576724009440","url":null,"abstract":"<p>Lead-based relaxor ferroelectrics exhibit giant piezoelectric properties owing to their heterogeneous structures. The average and local structures measured by single-crystal X-ray diffraction under DC and AC electric fields are reviewed in this article. The position-dependent local lattice strain and the distribution of polar nanodomains and nanoregions show strong electric field dependence, which contributes to the giant piezoelectric properties.</p>","PeriodicalId":48737,"journal":{"name":"Journal of Applied Crystallography","volume":"57 6","pages":"1700-1708"},"PeriodicalIF":5.2,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142764473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Understanding secondary order parameters in perovskites with tilted octahedra 了解倾斜八面体钙钛矿的二级参数
IF 5.2 3区 材料科学
Journal of Applied Crystallography Pub Date : 2024-10-16 DOI: 10.1107/S1600576724009397
Ekaterina G. Trotsenko, Mikhail V. Talanov
{"title":"Understanding secondary order parameters in perovskites with tilted octahedra","authors":"Ekaterina G. Trotsenko,&nbsp;Mikhail V. Talanov","doi":"10.1107/S1600576724009397","DOIUrl":"https://doi.org/10.1107/S1600576724009397","url":null,"abstract":"<p>In the family of perovskite materials, the tilts of <i>BX</i><sub>6</sub> octahedra are the most common type of structural distortion. Conventionally, the formation of low-symmetry perovskite phases with tilted octahedra is analyzed by considering only primary order parameters. However, octahedral tilting also gives rise to secondary order parameters which contribute to additional atomic displacements, ordering and lattice distortions. Our study highlights the significant impact of secondary order parameters on the structural formation and emergent physical properties of perovskites. Through group-theoretical and crystallographic analyses, we have identified all secondary order parameters within Glazer-type tilt systems and clarified their physical manifestations. We explore the fundamental symmetry relationships among various structural degrees of freedom in perovskites, including tilt-induced ferroelasticity, correlations between displacements and ordering of atoms occupying different positions, and the potential for rigid unit rotations and unconventional octahedral tilts. Particular emphasis is placed on the emergence of secondary order parameters and their coupling with primary order parameters, as well as their symmetry-based hierarchy, illustrated through a modified Bärnighausen tree. We applied our theoretical insights to elucidate phase transitions in well known perovskites such as CaTiO<sub>3</sub> and <i>R</i>MnO<sub>3</sub> (where <i>R</i> = La and lanthanide ions), thereby demonstrating the significant influence of secondary order parameters on crystal structure formation. Our results serve as a symmetry-based guide for the design, identification and structural characterization of perovskites with tilted octahedra, and for understanding tilt-induced physical properties.</p>","PeriodicalId":48737,"journal":{"name":"Journal of Applied Crystallography","volume":"57 6","pages":"1747-1763"},"PeriodicalIF":5.2,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142764446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Optimizing crucible geometry to improve the quality of AlN crystals by the physical vapor transport method 优化坩埚几何形状，利用物理蒸汽输运法提高AlN晶体质量
IF 5.2 3区 材料科学
Journal of Applied Crystallography Pub Date : 2024-10-16 DOI: 10.1107/S1600576724009087
Wenhao Cao, Shouzhi Wang, Ruixian Yu, Qiubo Li, Guodong Wang, Yajun Zhu, Yuzhu Wu, Lingshuang Lv, Jingliang Liu, Xiangang Xu, Lei Zhang
{"title":"Optimizing crucible geometry to improve the quality of AlN crystals by the physical vapor transport method","authors":"Wenhao Cao,&nbsp;Shouzhi Wang,&nbsp;Ruixian Yu,&nbsp;Qiubo Li,&nbsp;Guodong Wang,&nbsp;Yajun Zhu,&nbsp;Yuzhu Wu,&nbsp;Lingshuang Lv,&nbsp;Jingliang Liu,&nbsp;Xiangang Xu,&nbsp;Lei Zhang","doi":"10.1107/S1600576724009087","DOIUrl":"https://doi.org/10.1107/S1600576724009087","url":null,"abstract":"<p>In the conventional crucible structure for AlN crystal growth by physical vapor transport, owing to the long molecular transport path of Al vapor and the disruption of the gas flow by the presence of a deflector, the Al vapor easily forms polycrystals in the growth domain. The result is increased internal stress in the crystals and increased difficulty in growing large-sized crystals. On this basis, with the help of finite element simulations, a novel crucible structure is designed. This crucible not only optimizes the gas transport but also increases the radial gradient of the AlN crystal surface, making the enhanced growth rate in the central region more obvious. The thermal stresses between the deflector and the crystal are also reduced. High-quality AlN crystals with an FWHM of 79 arcsec were successfully grown with this structure, verifying the accuracy of finite element simulation of the growth of AlN crystals. Our work has important guiding significance for the growth of high-quality AlN crystals.</p>","PeriodicalId":48737,"journal":{"name":"Journal of Applied Crystallography","volume":"57 6","pages":"1764-1771"},"PeriodicalIF":5.2,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142764447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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