Maximilian Kai Reimann, Jutta Kösters, Rainer Pöttgen
The ternary auride Ba3Mg4Au4 was synthesized from the elements in a sealed tantalum ampoule. The Ba3Mg4Au4 structure was refined from single-crystal X-ray diffractometer data: Gd3Cu4Ge4 type, space group Immm, a = 447.95(10), b = 843.07(18), c = 1564.2(5) pm, wR2 = 0.0935, 680 F2 values, 23 variables. Ba3Mg4Au4 is a 1:2 intergrowth structure of BaAu2-(AlB2 type) and BaMg2Au-(MgCuAl2 type) related slabs. The two crystallographically independent gold atoms both have tricapped trigonal prismatic coordination, i.e. Au1@Mg6Ba3 and Au2@Mg2Ba6Au. The Au–Mg (284–303 pm) and Ba–Au (331–349 pm) distances cover small ranges that are close to the sums of the covalent radii. The magnesium atoms in the MgCuAl2-related slab show Mg–Mg distances of 320–332 pm. The different coloring variants of the Gd3Cu4Ge4 type are briefly discussed.
{"title":"Ba3Mg4Au4 – a ternary auride composed of BaAu2- and BaMg2Au-related slabs","authors":"Maximilian Kai Reimann, Jutta Kösters, Rainer Pöttgen","doi":"10.1515/znb-2023-0033","DOIUrl":"https://doi.org/10.1515/znb-2023-0033","url":null,"abstract":"The ternary auride Ba<jats:sub>3</jats:sub>Mg<jats:sub>4</jats:sub>Au<jats:sub>4</jats:sub> was synthesized from the elements in a sealed tantalum ampoule. The Ba<jats:sub>3</jats:sub>Mg<jats:sub>4</jats:sub>Au<jats:sub>4</jats:sub> structure was refined from single-crystal X-ray diffractometer data: Gd<jats:sub>3</jats:sub>Cu<jats:sub>4</jats:sub>Ge<jats:sub>4</jats:sub> type, space group <jats:italic>Immm</jats:italic>, <jats:italic>a</jats:italic> = 447.95(10), <jats:italic>b</jats:italic> = 843.07(18), <jats:italic>c</jats:italic> = 1564.2(5) pm, <jats:italic>wR</jats:italic>2 = 0.0935, 680 <jats:italic>F</jats:italic> <jats:sup>2</jats:sup> values, 23 variables. Ba<jats:sub>3</jats:sub>Mg<jats:sub>4</jats:sub>Au<jats:sub>4</jats:sub> is a 1:2 intergrowth structure of BaAu<jats:sub>2</jats:sub>-(AlB<jats:sub>2</jats:sub> type) and BaMg<jats:sub>2</jats:sub>Au-(MgCuAl<jats:sub>2</jats:sub> type) related slabs. The two crystallographically independent gold atoms both have tricapped trigonal prismatic coordination, i.e. Au1@Mg<jats:sub>6</jats:sub>Ba<jats:sub>3</jats:sub> and Au2@Mg<jats:sub>2</jats:sub>Ba<jats:sub>6</jats:sub>Au. The Au–Mg (284–303 pm) and Ba–Au (331–349 pm) distances cover small ranges that are close to the sums of the covalent radii. The magnesium atoms in the MgCuAl<jats:sub>2</jats:sub>-related slab show Mg–Mg distances of 320–332 pm. The different coloring variants of the Gd<jats:sub>3</jats:sub>Cu<jats:sub>4</jats:sub>Ge<jats:sub>4</jats:sub> type are briefly discussed.","PeriodicalId":23831,"journal":{"name":"Zeitschrift für Naturforschung B","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140574028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vahideh Alizadeh, Marco Garofalo, Carsten Urbach, Barbara Kirchner
A GPU-based implementation of the Hybrid Monte Carlo (HMC) algorithm is presented to explore its utility in the chemistry of solidification at the example of liquid to solid argon. We validate our implementation by comparing structural characteristics of argon fluid-like phases from HMC and MD simulations. Examining solidification, both MD and HMC show similar trends. Despite observable differences, MD simulations and HMC agree within the errors during the phase transition. Introducing voids decreases the solidification temperature, aiding in the formation of a well-structured solids. Further, our findings highlight the importance of larger system sizes in simulating solidification processes. Simulations with a temperature dependent potential show ambiguous results for the solidification which may be attributed to the small system sizes. Future work aims to expand HMC capabilities for complex chemical phenomena in phase transitions.
{"title":"A Hybrid Monte Carlo study of argon solidification","authors":"Vahideh Alizadeh, Marco Garofalo, Carsten Urbach, Barbara Kirchner","doi":"10.1515/znb-2023-0107","DOIUrl":"https://doi.org/10.1515/znb-2023-0107","url":null,"abstract":"A GPU-based implementation of the Hybrid Monte Carlo (HMC) algorithm is presented to explore its utility in the chemistry of solidification at the example of liquid to solid argon. We validate our implementation by comparing structural characteristics of argon fluid-like phases from HMC and MD simulations. Examining solidification, both MD and HMC show similar trends. Despite observable differences, MD simulations and HMC agree within the errors during the phase transition. Introducing voids decreases the solidification temperature, aiding in the formation of a well-structured solids. Further, our findings highlight the importance of larger system sizes in simulating solidification processes. Simulations with a temperature dependent potential show ambiguous results for the solidification which may be attributed to the small system sizes. Future work aims to expand HMC capabilities for complex chemical phenomena in phase transitions.","PeriodicalId":23831,"journal":{"name":"Zeitschrift für Naturforschung B","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140591134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anna Jodlbauer, Maria Gombotz, Bernhard Gadermaier, Paul Heitjans, H. Martin R. Wilkening
The compound AgI crystallizes, depending on temperature and pressure, with various crystal structures. While α-AgI is the stable form at elevated temperatures, the β and the γ forms exist at lower temperatures. Variants with stacking sequences different than in pure β-AgI and γ-AgI enrich the complex crystallographic situation for AgI. In the study presented here, we converted a mixture of β-AgI and γ-AgI into nanostructured γ-AgI by mechanical treatment, that is, by high-energy ball milling of such a mixture under ambient conditions. Our work extends an earlier study by Ahmad (Z. Naturforsch. 2015, 70b, 17). We used variable-temperature, potentiostatic conductivity spectroscopy as well as electric modulus measurements to characterize the electric transport parameters. For the case that the sample is heated to temperatures near and above 420 K, preliminary information on the “resistance” of the electric conductivity against healing of defects are also collected. As compared to the unmilled but mixed sample, whose Ag+ ionic transport is dominated by those ions residing in the γ-phase of AgI (0.25 eV vs. 0.46 eV in β-AgI), ball milling only leads to a small increase in overall electric conductivity (by a factor of 3–4) for nanocrystalline γ-AgI (0.25 eV). This observation is perfectly in line with a recent observation for the fast ion conductor Li10GeP2S12 (Hogrefe et al., J. Am. Chem. Soc. 2022, 144, 9597): In materials with already rapid diffusion pathways, nanostructuring and the introduction of defects and distortions do not lead to significantly enhanced ion transport. Here, a careful analysis of data from conductivity and modulus spectroscopy helps identify which dynamic parameters are mainly responsible for the change in the overall conductivity upon mechanical treatment of coarse-grained γ-AgI.
{"title":"Ionic conductivity of nanocrystalline γ-AgI prepared by high-energy ball milling","authors":"Anna Jodlbauer, Maria Gombotz, Bernhard Gadermaier, Paul Heitjans, H. Martin R. Wilkening","doi":"10.1515/znb-2023-0081","DOIUrl":"https://doi.org/10.1515/znb-2023-0081","url":null,"abstract":"The compound AgI crystallizes, depending on temperature and pressure, with various crystal structures. While <jats:italic>α</jats:italic>-AgI is the stable form at elevated temperatures, the <jats:italic>β</jats:italic> and the <jats:italic>γ</jats:italic> forms exist at lower temperatures. Variants with stacking sequences different than in pure <jats:italic>β</jats:italic>-AgI and <jats:italic>γ</jats:italic>-AgI enrich the complex crystallographic situation for AgI. In the study presented here, we converted a mixture of <jats:italic>β</jats:italic>-AgI and <jats:italic>γ</jats:italic>-AgI into nanostructured <jats:italic>γ</jats:italic>-AgI by mechanical treatment, that is, by high-energy ball milling of such a mixture under ambient conditions. Our work extends an earlier study by Ahmad (Z. Naturforsch. 2015, 70b, 17). We used variable-temperature, potentiostatic conductivity spectroscopy as well as electric modulus measurements to characterize the electric transport parameters. For the case that the sample is heated to temperatures near and above 420 K, preliminary information on the “resistance” of the electric conductivity against healing of defects are also collected. As compared to the unmilled but mixed sample, whose Ag<jats:sup>+</jats:sup> ionic transport is dominated by those ions residing in the <jats:italic>γ</jats:italic>-phase of AgI (0.25 eV vs. 0.46 eV in <jats:italic>β</jats:italic>-AgI), ball milling only leads to a small increase in overall electric conductivity (by a factor of 3–4) for nanocrystalline <jats:italic>γ</jats:italic>-AgI (0.25 eV). This observation is perfectly in line with a recent observation for the fast ion conductor Li<jats:sub>10</jats:sub>GeP<jats:sub>2</jats:sub>S<jats:sub>12</jats:sub> (Hogrefe et al., J. Am. Chem. Soc. 2022, 144, 9597): In materials with already rapid diffusion pathways, nanostructuring and the introduction of defects and distortions do not lead to significantly enhanced ion transport. Here, a careful analysis of data from conductivity and modulus spectroscopy helps identify which dynamic parameters are mainly responsible for the change in the overall conductivity upon mechanical treatment of coarse-grained <jats:italic>γ</jats:italic>-AgI.","PeriodicalId":23831,"journal":{"name":"Zeitschrift für Naturforschung B","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140573863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work presents a periodic extension of the GFN-FF force field for molecular crystals named mcGFN-FF. Non-covalent interactions in the force field are adjusted to reduce the systematic overbinding of the original, molecular version for molecular crystals. A diverse set of molecular crystal benchmarks for lattice energies and unit cell volumes is studied. The modified force field shows good results with a mean absolute relative deviation (MARD) of 19.9 % for lattice energies and 10.0 % for unit cell volumes. In many cases, mcGFN-FF approaches the accuracy of the GFN1-xTB quantum chemistry method which has an MARD of 18.7 % for lattice energies and 6.2 % for unit cell volumes. Further, the newly compiled mcVOL22 benchmark set is presented which features r2SCAN-D4/900 eV DFT reference volumes for molecular crystals with phosphorus-, sulfur-, and chlorine-containing compounds of various sizes. Overall, the mcGFN-FF poses an efficient tool for the optimization and energetic screening of molecular crystals containing elements up to radon.
{"title":"mcGFN-FF: an accurate force field for optimization and energetic screening of molecular crystals","authors":"Stefan Grimme, Thomas Rose","doi":"10.1515/znb-2023-0088","DOIUrl":"https://doi.org/10.1515/znb-2023-0088","url":null,"abstract":"This work presents a periodic extension of the GFN-FF force field for molecular crystals named mcGFN-FF. Non-covalent interactions in the force field are adjusted to reduce the systematic overbinding of the original, molecular version for molecular crystals. A diverse set of molecular crystal benchmarks for lattice energies and unit cell volumes is studied. The modified force field shows good results with a mean absolute relative deviation (MARD) of 19.9 % for lattice energies and 10.0 % for unit cell volumes. In many cases, mcGFN-FF approaches the accuracy of the GFN1-xTB quantum chemistry method which has an MARD of 18.7 % for lattice energies and 6.2 % for unit cell volumes. Further, the newly compiled mcVOL22 benchmark set is presented which features r<jats:sup>2</jats:sup>SCAN-D4/900 eV DFT reference volumes for molecular crystals with phosphorus-, sulfur-, and chlorine-containing compounds of various sizes. Overall, the mcGFN-FF poses an efficient tool for the optimization and energetic screening of molecular crystals containing elements up to radon.","PeriodicalId":23831,"journal":{"name":"Zeitschrift für Naturforschung B","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140574009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Robert Glaum, Marcos Schöneborn, Felix Reinauer, Halil Shaqiri, Saiful M. Islam
The crystal structures of TiIII4[Si2O(PO4)6] (P3‾$Poverline{3}$, Z = 3, a = 14.733(1), c = 7.363(1) Å, R1 = 0.040, wR2 = 0.098, 7649 ind. refl., 170 variables), FeII0.79TiIII2.42TiIV0.79[Si2O(PO4)6] (P3‾$Poverline{3}$, Z = 3, a = 14.6534(2), c = 7.3829(1) Å, R1 = 0.036, wR2 = 0.088, 4026 ind. refl., 171 variables), and TiIII2TiIV6(PO4)6[Si2O(PO4)6] (R3‾$Roverline{3}$, Z = 1, a = 8.446(2), c = 44.21(2) Å, R1 = 0.047, wR2 = 0.120, 1373 ind. refl., 109 variables) have been refined from single-crystal data. The structures show hexagonal closest packing of phosphate groups with metal cations and [Si2O] groups occupying octahedral voids [□(PO4)6]. The close relationship of these and other silicophosphate structures to the NiAs and β-Fe2(SO4
TiIII 4[Si2O(PO4)6]（P 3 ‾ $Poverline{3}$ , Z = 3, a = 14.733(1), c = 7.363(1) Å, R1 = 0.040, wR2 = 0.098, 7649 ind、170 变量）、FeII 0.79TiIII 2.42TiIV 0.79[Si2O(PO4)6] ( P 3 ‾ $Poverline{3}$ , Z = 3, a = 14.6534(2), c = 7.3829(1) Å, R1 = 0.036, wR2 = 0.088, 4026 ind. refl、171 个变量）和 TiIII 2TiIV 6(PO4)6[Si2O(PO4)6] （R 3 ‾ $Roverline{3}$ , Z = 1, a = 8.446(2), c = 44.21(2) Å, R1 = 0.047, wR2 = 0.120, 1373 ind.这些结构显示，磷酸盐基团与金属阳离子和占据八面体空隙[□(PO4)6]的[Si2O]基团呈六方最密堆积。这些结构和其他磷酸硅结构与 NiAs 和 β-Fe2(SO4)3（另见 NaZr2(PO4)3 "NASICON"）结构类型的密切关系是通过基团/亚基考虑合理化的。这种对称方法表明，硅磷酸盐中很可能存在系统孪晶，从而可能导致晶体结构细化错误。我们的研究有力地表明，文献中报道的硅磷酸盐的正确成分 "M III 3P5SiO19"（M = Cr、V、Fe、Mo）实际上是 M III 4-[Si2O(PO4)6]。通过与 Ti2O3、TiP2O7 和 FeTiO3 比较，将混合价化合物中阳离子位点的氧化态进行了分配。深蓝色 FeII 0.79TiIII 2.42TiIV 0.79[Si2O(PO4)6]的粉末反射光谱在 ν ˜ $widetilde{nu }$ = 17,500 cm-1 处显示了强烈的 IVCT 转变，磁感应强度数据与所提出的氧化态非常吻合。
{"title":"Crystal structures and crystallographic classification of titanium silicophosphates – with a note on structure and composition of silicophosphates “M 3P5SiO19”","authors":"Robert Glaum, Marcos Schöneborn, Felix Reinauer, Halil Shaqiri, Saiful M. Islam","doi":"10.1515/znb-2023-0099","DOIUrl":"https://doi.org/10.1515/znb-2023-0099","url":null,"abstract":"The crystal structures of Ti<jats:sup>III</jats:sup> <jats:sub>4</jats:sub>[Si<jats:sub>2</jats:sub>O(PO<jats:sub>4</jats:sub>)<jats:sub>6</jats:sub>] (<jats:inline-formula> <jats:alternatives> <m:math xmlns:m=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <m:mrow> <m:mi>P</m:mi> <m:mover accent=\"true\"> <m:mn>3</m:mn> <m:mo>‾</m:mo> </m:mover> </m:mrow> </m:math> <jats:tex-math>$Poverline{3}$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"graphic/j_znb-2023-0099_ineq_001.png\" /> </jats:alternatives> </jats:inline-formula>, <jats:italic>Z</jats:italic> = 3, <jats:italic>a</jats:italic> = 14.733(1), <jats:italic>c</jats:italic> = 7.363(1) Å, <jats:italic>R</jats:italic>1 = 0.040, <jats:italic>wR</jats:italic>2 = 0.098, 7649 ind. refl., 170 variables), Fe<jats:sup>II</jats:sup> <jats:sub>0.79</jats:sub>Ti<jats:sup>III</jats:sup> <jats:sub>2.42</jats:sub>Ti<jats:sup>IV</jats:sup> <jats:sub>0.79</jats:sub>[Si<jats:sub>2</jats:sub>O(PO<jats:sub>4</jats:sub>)<jats:sub>6</jats:sub>] (<jats:inline-formula> <jats:alternatives> <m:math xmlns:m=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <m:mrow> <m:mi>P</m:mi> <m:mover accent=\"true\"> <m:mn>3</m:mn> <m:mo>‾</m:mo> </m:mover> </m:mrow> </m:math> <jats:tex-math>$Poverline{3}$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"graphic/j_znb-2023-0099_ineq_002.png\" /> </jats:alternatives> </jats:inline-formula>, <jats:italic>Z</jats:italic> = 3, <jats:italic>a</jats:italic> = 14.6534(2), <jats:italic>c</jats:italic> = 7.3829(1) Å, <jats:italic>R</jats:italic>1 = 0.036, <jats:italic>wR</jats:italic>2 = 0.088, 4026 ind. refl., 171 variables), and Ti<jats:sup>III</jats:sup> <jats:sub>2</jats:sub>Ti<jats:sup>IV</jats:sup> <jats:sub>6</jats:sub>(PO<jats:sub>4</jats:sub>)<jats:sub>6</jats:sub>[Si<jats:sub>2</jats:sub>O(PO<jats:sub>4</jats:sub>)<jats:sub>6</jats:sub>] (<jats:inline-formula> <jats:alternatives> <m:math xmlns:m=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <m:mrow> <m:mi>R</m:mi> <m:mover accent=\"true\"> <m:mn>3</m:mn> <m:mo>‾</m:mo> </m:mover> </m:mrow> </m:math> <jats:tex-math>$Roverline{3}$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"graphic/j_znb-2023-0099_ineq_003.png\" /> </jats:alternatives> </jats:inline-formula>, <jats:italic>Z</jats:italic> = 1, <jats:italic>a</jats:italic> = 8.446(2), <jats:italic>c</jats:italic> = 44.21(2) Å, <jats:italic>R</jats:italic>1 = 0.047, <jats:italic>wR</jats:italic>2 = 0.120, 1373 ind. refl., 109 variables) have been refined from single-crystal data. The structures show hexagonal closest packing of phosphate groups with metal cations and [Si<jats:sub>2</jats:sub>O] groups occupying octahedral voids [□(PO<jats:sub>4</jats:sub>)<jats:sub>6</jats:sub>]. The close relationship of these and other silicophosphate structures to the NiAs and <jats:italic>β</jats:italic>-Fe<jats:sub>2</jats:sub>(SO<jats:sub>4</jat","PeriodicalId":23831,"journal":{"name":"Zeitschrift für Naturforschung B","volume":"120 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140573865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Juan Diego Samaniego-Rojas, Robin Gaumard, José Alejandre, Tzonka Mineva, Gerald Geudtner, Andreas M. Köster
The implementation of the cyclic cluster model (CCM) for molecular mechanics is presented in the framework of the computational chemistry program deMon2k. Because the CCM is particularly well-suited for the description of periodic systems with defects, it can be used for periodic QM/MM approaches where the non-periodic QM part is treated as a defect in a periodic MM surrounding. To this end, we present here the explicit formulae for the evaluation of the Ewald sum and its first- and second-order derivatives as implemented in deMon2k. The outlined implementation was tested in molecular dynamics (MD) simulations and periodic structure optimization calculations. MD simulations of an argon system were carried out using the Nosé-Hoover chain (NHC) thermostat and the Martyna-Tobias-Klein (MTK) barostat to control the temperature and pressure of the system, respectively. For the validation of CCM structure optimization a set of molecular crystals were optimized using the Ewald method for the evaluation of the electrostatic interactions. Two optimization procedures for the determination of the atomic positions and CCM cell parameters were tested. Our results show that the simultaneous optimization of the atomic positions and cell parameters is most efficient.
{"title":"A molecular mechanics implementation of the cyclic cluster model","authors":"Juan Diego Samaniego-Rojas, Robin Gaumard, José Alejandre, Tzonka Mineva, Gerald Geudtner, Andreas M. Köster","doi":"10.1515/znb-2023-0090","DOIUrl":"https://doi.org/10.1515/znb-2023-0090","url":null,"abstract":"The implementation of the cyclic cluster model (CCM) for molecular mechanics is presented in the framework of the computational chemistry program <jats:sc>deMon</jats:sc>2<jats:sc>k</jats:sc>. Because the CCM is particularly well-suited for the description of periodic systems with defects, it can be used for periodic QM/MM approaches where the non-periodic QM part is treated as a defect in a periodic MM surrounding. To this end, we present here the explicit formulae for the evaluation of the Ewald sum and its first- and second-order derivatives as implemented in <jats:sc>deMon</jats:sc>2<jats:sc>k</jats:sc>. The outlined implementation was tested in molecular dynamics (MD) simulations and periodic structure optimization calculations. MD simulations of an argon system were carried out using the Nosé-Hoover chain (NHC) thermostat and the Martyna-Tobias-Klein (MTK) barostat to control the temperature and pressure of the system, respectively. For the validation of CCM structure optimization a set of molecular crystals were optimized using the Ewald method for the evaluation of the electrostatic interactions. Two optimization procedures for the determination of the atomic positions and CCM cell parameters were tested. Our results show that the simultaneous optimization of the atomic positions and cell parameters is most efficient.","PeriodicalId":23831,"journal":{"name":"Zeitschrift für Naturforschung B","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140574102","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The monoclinic β-polymorph of gallium oxide is a semiconductor with an ultra-wide bandgap. It is becoming increasingly significant for various technological applications. We have investigated the tracer self-diffusion of oxygen in β-Ga2O3 single crystals as a function of the oxygen partial pressure (2, 20 and 200 mbar) at a temperature of 1375 °C. Isotopically enriched 18O2 gas was used as a tracer source and secondary ion mass spectrometry to analyze depth profiles. We observed that, with decreasing oxygen partial pressure, the diffusivities at a given temperature increase significantly. We suggest that this behaviour can be explained by a change in the diffusion mechanism from oxygen interstitials to oxygen vacancies.
氧化镓的单斜β多晶体是一种具有超宽带隙的半导体。它在各种技术应用中的重要性与日俱增。我们研究了在 1375 °C 温度下，β-Ga2O3 单晶中氧的示踪自扩散与氧分压（2、20 和 200 毫巴）的函数关系。使用同位素富集的 18O2 气体作为示踪源，并使用二次离子质谱分析深度剖面。我们观察到，随着氧分压的降低，特定温度下的扩散率显著增加。我们认为，这种行为可以用从氧间隙到氧空位的扩散机制变化来解释。
{"title":"Oxygen diffusion in β-Ga2O3 single crystals under different oxygen partial pressures at 1375 °C","authors":"Johanna Uhlendorf, Harald Schmidt","doi":"10.1515/znb-2023-0091","DOIUrl":"https://doi.org/10.1515/znb-2023-0091","url":null,"abstract":"The monoclinic <jats:italic>β</jats:italic>-polymorph of gallium oxide is a semiconductor with an ultra-wide bandgap. It is becoming increasingly significant for various technological applications. We have investigated the tracer self-diffusion of oxygen in <jats:italic>β</jats:italic>-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> single crystals as a function of the oxygen partial pressure (2, 20 and 200 mbar) at a temperature of 1375 °C. Isotopically enriched <jats:sup>18</jats:sup>O<jats:sub>2</jats:sub> gas was used as a tracer source and secondary ion mass spectrometry to analyze depth profiles. We observed that, with decreasing oxygen partial pressure, the diffusivities at a given temperature increase significantly. We suggest that this behaviour can be explained by a change in the diffusion mechanism from oxygen interstitials to oxygen vacancies.","PeriodicalId":23831,"journal":{"name":"Zeitschrift für Naturforschung B","volume":"92 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140573864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A new member of the A2B5C5X16 family of compounds – the first one containing Se – has been synthesized. Following a one-step mechanochemical synthesis route, starting from the binary selenides and Mg metal, Cu2Mg5Sn5Se16 has been obtained. Structural evaluation was carried out using X-ray diffraction with subsequent Rietveld refinement. Cu2Mg5Sn5Se16 adopts the spinel type with space group Fd3‾$overline{3}$m and exhibits a statistical distribution of Cu, Mg, and Sn on Wyckoff position 16d whereas Wyckoff position 8a is only occupied by Mg. Despite the fact that structures containing MgSe4 tetrahedra are rare in the literature, it appeared to be the most plausible way of distributing the cations in this compound.
我们合成了 A2B5C5X16 化合物家族的一个新成员--第一个含 Se 的化合物。从二元硒化物和金属镁开始，通过一步机械化学合成路线，获得了 Cu2Mg5Sn5Se16。利用 X 射线衍射和随后的里特维尔德精炼进行了结构评估。Cu2Mg5Sn5Se16 采用空间群为 Fd 3 ‾ $overline{3}$ m 的尖晶石类型，并显示出铜、镁和锡在 Wyckoff 位置 16d 上的统计分布，而 Wyckoff 位置 8a 仅被镁占据。尽管含有 MgSe4 四面体的结构在文献中并不多见，但这似乎是该化合物中阳离子分布的最合理方式。
{"title":"Cu2Mg5Sn5Se16 – the first selenospinel of the A2B5C5X16 type","authors":"Kevin D. Profita, Eva M. Heppke","doi":"10.1515/znb-2023-0098","DOIUrl":"https://doi.org/10.1515/znb-2023-0098","url":null,"abstract":"A new member of the A<jats:sub>2</jats:sub>B<jats:sub>5</jats:sub>C<jats:sub>5</jats:sub>X<jats:sub>16</jats:sub> family of compounds – the first one containing Se – has been synthesized. Following a one-step mechanochemical synthesis route, starting from the binary selenides and Mg metal, Cu<jats:sub>2</jats:sub>Mg<jats:sub>5</jats:sub>Sn<jats:sub>5</jats:sub>Se<jats:sub>16</jats:sub> has been obtained. Structural evaluation was carried out using X-ray diffraction with subsequent Rietveld refinement. Cu<jats:sub>2</jats:sub>Mg<jats:sub>5</jats:sub>Sn<jats:sub>5</jats:sub>Se<jats:sub>16</jats:sub> adopts the spinel type with space group <jats:italic>Fd</jats:italic> <jats:inline-formula> <jats:alternatives> <m:math xmlns:m=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <m:mrow> <m:mover accent=\"true\"> <m:mn>3</m:mn> <m:mo>‾</m:mo> </m:mover> </m:mrow> </m:math> <jats:tex-math>$overline{3}$</jats:tex-math> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" xlink:href=\"graphic/j_znb-2023-0098_ineq_001.png\" /> </jats:alternatives> </jats:inline-formula> <jats:italic>m</jats:italic> and exhibits a statistical distribution of Cu, Mg, and Sn on Wyckoff position 16<jats:italic>d</jats:italic> whereas Wyckoff position 8<jats:italic>a</jats:italic> is only occupied by Mg. Despite the fact that structures containing MgSe<jats:sub>4</jats:sub> tetrahedra are rare in the literature, it appeared to be the most plausible way of distributing the cations in this compound.","PeriodicalId":23831,"journal":{"name":"Zeitschrift für Naturforschung B","volume":"149 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140574047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Thomas Bredow zum 60. Geburtstag gewidmet","authors":"M. Wilkening, Lisa Ballmann, M. Lerch","doi":"10.1515/znb-2023-0083","DOIUrl":"https://doi.org/10.1515/znb-2023-0083","url":null,"abstract":"","PeriodicalId":23831,"journal":{"name":"Zeitschrift für Naturforschung B","volume":"39 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140789451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A Ni(II) complex, [Ni2(FDC)2(4,4′-BMIBP)2(H2O)2·3H2O]n (1) (4,4′-BMIBP = 4,4’-bis(2-methyl-imidazolyl)biphenyl, H2FDC = 2,5-furandicarboxylic acid) was hydrothermally synthesized and structurally characterized. Complex 1 possesses a polycatenated architecture based on an undulated (4,4)-sql layer. Complex 1 can be used for the selective detection of nitrofurantoin (NFT) in aqueous solutions. The luminescence quenching mechanism of complex 1 is attributed to the competitive absorption.
{"title":"A polycatenated nickel(II) coordination polymer as a luminescence sensor for nitrofurantoin in aqueous medium","authors":"Liang Zhang, Weiwei Cheng","doi":"10.1515/znb-2023-0111","DOIUrl":"https://doi.org/10.1515/znb-2023-0111","url":null,"abstract":"A Ni(II) complex, [Ni<jats:sub>2</jats:sub>(FDC)<jats:sub>2</jats:sub>(4,4′-BMIBP)<jats:sub>2</jats:sub>(H<jats:sub>2</jats:sub>O)<jats:sub>2</jats:sub>·3H<jats:sub>2</jats:sub>O]<jats:sub> <jats:italic>n</jats:italic> </jats:sub> (1) (4,4′-BMIBP = 4,4’-bis(2-methyl-imidazolyl)biphenyl, H<jats:sub>2</jats:sub>FDC = 2,5-furandicarboxylic acid) was hydrothermally synthesized and structurally characterized. Complex 1 possesses a polycatenated architecture based on an undulated (4,4)-sql layer. Complex 1 can be used for the selective detection of nitrofurantoin (NFT) in aqueous solutions. The luminescence quenching mechanism of complex 1 is attributed to the competitive absorption.","PeriodicalId":23831,"journal":{"name":"Zeitschrift für Naturforschung B","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140147883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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