Perovskite La0.6Sr0.4Fe1−xCuxO3−δ (x = 0, 0.05, 0.1, and 0.2) polycrystalline samples have been synthesized in air and investigated by X‐Ray diffraction, scanning electron microscope, magnetization, and mechanical spectroscopy. An antiferromagnetic transition is observed around 300 K, while no corresponding anomaly is observed in the mechanical spectrum, indicating the absence of conventional magnetoelastic coupling. For La0.6Sr0.4FeO3, an internal friction peak (P1) presents around 140 K and shifts to lower temperatures with increasing Cu‐doping content. Meanwhile, a magnetic anomaly is also observed around P1 peak temperature. As explained, the P1 peak is related to the freezing of the ferroelastic domain walls, and the mechanical energy dissipation is induced by the lagging variation of the octahedral tilting under the alternating stress. This work suggests a peculiar magnetic property of the octahedra within ferroelastic domain walls.
我们在空气中合成了透辉石 La0.6Sr0.4Fe1-xCuxO3-δ（x = 0、0.05、0.1 和 0.2）多晶样品，并通过 X 射线衍射、扫描电子显微镜、磁化和机械光谱进行了研究。在 300 K 附近观察到了反铁磁性转变，而在机械光谱中没有观察到相应的异常，这表明不存在传统的磁弹性耦合。对于 La0.6Sr0.4FeO3，一个内摩擦峰（P1）出现在 140 K 左右，并随着铜掺杂含量的增加而向更低的温度移动。同时，在 P1 峰温度附近还观察到磁异常。据解释，P1 峰与铁弹性域壁的冻结有关，而机械能耗散则是由交变应力下八面体倾斜的滞后变化引起的。这项研究表明，铁弹性畴壁内的八面体具有奇特的磁性。
{"title":"Anelastic and Magnetic Properties of Polycrystalline La0.6Sr0.4Fe1−xCuxO3−δ","authors":"Boren Xue, Xuenong Ying, Xiaomei Lu","doi":"10.1002/pssb.202400218","DOIUrl":"https://doi.org/10.1002/pssb.202400218","url":null,"abstract":"Perovskite La<jats:sub>0.6</jats:sub>Sr<jats:sub>0.4</jats:sub>Fe<jats:sub>1−<jats:italic>x</jats:italic></jats:sub>Cu<jats:sub><jats:italic>x</jats:italic></jats:sub>O<jats:sub>3−<jats:italic>δ</jats:italic></jats:sub> (<jats:italic>x</jats:italic> = 0, 0.05, 0.1, and 0.2) polycrystalline samples have been synthesized in air and investigated by X‐Ray diffraction, scanning electron microscope, magnetization, and mechanical spectroscopy. An antiferromagnetic transition is observed around 300 K, while no corresponding anomaly is observed in the mechanical spectrum, indicating the absence of conventional magnetoelastic coupling. For La<jats:sub>0.6</jats:sub>Sr<jats:sub>0.4</jats:sub>FeO<jats:sub>3</jats:sub>, an internal friction peak (P1) presents around 140 K and shifts to lower temperatures with increasing Cu‐doping content. Meanwhile, a magnetic anomaly is also observed around P1 peak temperature. As explained, the P1 peak is related to the freezing of the ferroelastic domain walls, and the mechanical energy dissipation is induced by the lagging variation of the octahedral tilting under the alternating stress. This work suggests a peculiar magnetic property of the octahedra within ferroelastic domain walls.","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"46 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141780220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This comprehensive study relates to the most radiation‐sensitive peaks (450 and 550 K) of high‐temperature (300–775 K) thermally stimulated luminescence (TSL) of MgO:Mn2+ crystals, with impurity content of 77, 155, and 285 ppm, irradiated with fast electrons. For a more complete and clearer picture of the nonmonotonic (polymodal) radiation processes stimulated in doped crystals, the results of a study of a group of nominally pure crystals irradiated under the same experimental conditions are also considered. Based on the correlation of the dose dependences of the studied characteristics, the mechanisms of TSL peaks formation are established. Despite a much lower concentration than divalent manganese ions, ferric ions cause significant changes in thermoluminescence and its quenching in irradiated MgO:Mn2+ crystals.
{"title":"Influence of Polymodal Radiation Processes on Thermoluminescence and Its Quenching in MgO:Mn2+ Crystals","authors":"Vakhtang Kvatchadze, Guram Dekanozishvili, Meri Abramishvili, Zaira Akhvlediani, Dimitri Driaev, Valery Tavkhelidze","doi":"10.1002/pssb.202400112","DOIUrl":"https://doi.org/10.1002/pssb.202400112","url":null,"abstract":"This comprehensive study relates to the most radiation‐sensitive peaks (450 and 550 K) of high‐temperature (300–775 K) thermally stimulated luminescence (TSL) of MgO:Mn<jats:sup>2+</jats:sup> crystals, with impurity content of 77, 155, and 285 ppm, irradiated with fast electrons. For a more complete and clearer picture of the nonmonotonic (polymodal) radiation processes stimulated in doped crystals, the results of a study of a group of nominally pure crystals irradiated under the same experimental conditions are also considered. Based on the correlation of the dose dependences of the studied characteristics, the mechanisms of TSL peaks formation are established. Despite a much lower concentration than divalent manganese ions, ferric ions cause significant changes in thermoluminescence and its quenching in irradiated MgO:Mn<jats:sup>2+</jats:sup> crystals.","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"40 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141739733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maria A. Cardona, Joseph N. Grima, Ken E. Evans, Ruben Gatt
Materials exhibiting auxetic behavior have garnered significant interest due to their potential applications across various fields, with synthetic auxetic materials being one such group. Theoretical studies have demonstrated the potential for various organic polymeric systems to exhibit auxetic behavior. However, to date, only a few synthesized molecular systems have shown some degree of auxetic behavior. Among the theoretical classes of molecular systems that have attracted attention are calix[4]arene systems in the “egg‐rack” conformation. While the theoretical systems proposed in the literature have been deemed difficult to synthesize, calix[4]arene chemistry has advanced tremendously in recent years. In fact, a number of molecular systems with configurations similar to those predicted to exhibit a negative Poisson's ratio have been synthesized, albeit with different chemical moieties. Consequently, it is deemed valuable to study the potential of these synthesized systems to exhibit a negative Poisson's ratio through force‐field‐based simulations. This study is extended to include theoretical calix[4]arene systems linked by acetylene moieties, which are also potentially synthesizable through known methods. It is suggested that these materials can exhibit auxetic behavior when subjected to on‐axis loading in the [001] direction. A detailed mechanistic study of these systems is also conducted.
{"title":"On the Auxetic Potential of Synthesizable Calix[4]arene Polymers","authors":"Maria A. Cardona, Joseph N. Grima, Ken E. Evans, Ruben Gatt","doi":"10.1002/pssb.202400213","DOIUrl":"https://doi.org/10.1002/pssb.202400213","url":null,"abstract":"Materials exhibiting auxetic behavior have garnered significant interest due to their potential applications across various fields, with synthetic auxetic materials being one such group. Theoretical studies have demonstrated the potential for various organic polymeric systems to exhibit auxetic behavior. However, to date, only a few synthesized molecular systems have shown some degree of auxetic behavior. Among the theoretical classes of molecular systems that have attracted attention are calix[4]arene systems in the “egg‐rack” conformation. While the theoretical systems proposed in the literature have been deemed difficult to synthesize, calix[4]arene chemistry has advanced tremendously in recent years. In fact, a number of molecular systems with configurations similar to those predicted to exhibit a negative Poisson's ratio have been synthesized, albeit with different chemical moieties. Consequently, it is deemed valuable to study the potential of these synthesized systems to exhibit a negative Poisson's ratio through force‐field‐based simulations. This study is extended to include theoretical calix[4]arene systems linked by acetylene moieties, which are also potentially synthesizable through known methods. It is suggested that these materials can exhibit auxetic behavior when subjected to on‐axis loading in the [001] direction. A detailed mechanistic study of these systems is also conducted.","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"41 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141739736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tailoring the electronic and optical properties of nitride‐based alloys for optoelectronic device applications in the ultraviolet and red spectral range has attracted significant attention in recent years. Adding boron nitride (BN) to indium gallium nitride (In,Ga)N alloys can help to control the lattice mismatch between (In,Ga)N and GaN and may thus allow to reduce strain‐related defect formation. However, understanding of the impact of BN on the electronic properties of III‐N alloys, in particular the influence of experimentally observed boron atom clustering, is sparse. This work presents first‐principles calculations investigating the electronic properties of highly mismatched (B,In)N alloys with boron contents between 2% and 7%. Special attention is paid to the impact of the alloy microstructure. While the results show that the lattice constants of such alloys largely agree with lattice constants determined from a Vegard approximation, the electronic structure strongly depends on the local boron atom configuration. For instance, if boron atoms are dispersed throughout the structure and are not sharing nitrogen atoms, the band gap of (B,In)N alloys is largely unaffected and stays close to the gap of pristine InN. However, in the case of boron atom clustering, i.e., when boron atoms are sharing nitrogen atoms, the band gap can be strongly reduced, often leading to a metallic state in (B,In)N alloys. These strong band gap reductions are mainly driven by carrier localization effects in the valence band. Our calculations thus show that the electronic structure of (B,In)N alloys strongly depends on the alloy microstructure and that boron atom clustering plays an important role in understanding the electronic and optical properties of these emerging materials.
{"title":"Impact of Boron Atom Clustering on the Electronic Structure of (B,In)N Alloys","authors":"Cara‐Lena Nies, Stefan Schulz","doi":"10.1002/pssb.202400016","DOIUrl":"https://doi.org/10.1002/pssb.202400016","url":null,"abstract":"Tailoring the electronic and optical properties of nitride‐based alloys for optoelectronic device applications in the ultraviolet and red spectral range has attracted significant attention in recent years. Adding boron nitride (BN) to indium gallium nitride (In,Ga)N alloys can help to control the lattice mismatch between (In,Ga)N and GaN and may thus allow to reduce strain‐related defect formation. However, understanding of the impact of BN on the electronic properties of III‐N alloys, in particular the influence of experimentally observed boron atom clustering, is sparse. This work presents first‐principles calculations investigating the electronic properties of highly mismatched (B,In)N alloys with boron contents between 2% and 7%. Special attention is paid to the impact of the alloy microstructure. While the results show that the lattice constants of such alloys largely agree with lattice constants determined from a Vegard approximation, the electronic structure strongly depends on the local boron atom configuration. For instance, if boron atoms are dispersed throughout the structure and are not sharing nitrogen atoms, the band gap of (B,In)N alloys is largely unaffected and stays close to the gap of pristine InN. However, in the case of boron atom clustering, i.e., when boron atoms are sharing nitrogen atoms, the band gap can be strongly reduced, often leading to a metallic state in (B,In)N alloys. These strong band gap reductions are mainly driven by carrier localization effects in the valence band. Our calculations thus show that the electronic structure of (B,In)N alloys strongly depends on the alloy microstructure and that boron atom clustering plays an important role in understanding the electronic and optical properties of these emerging materials.","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"9 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141614188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jiu‐Jiu Chen, Qiu‐Shuang Yang, Shao‐Yong Huo, Chun‐Ming Fu
Topological rainbow trapping, which can separate and trap different frequencies of topological states into different positions, plays a key role in topological acoustic devices. However, few schemes have been proposed to realize multidimensional topological rainbow trapping effects with the hierarchy of edge and corner, which has partly restricted their practical applications in multifunctional integrated acoustic devices. Herein, a tactic to realize a multidimensional topological rainbow trapping of acoustic wave with the hierarchy of edge and corner in the second‐order topological sonic crystals is proposed. Based on the designing of a self‐ordering structure to both induce the topological phases of the bulk and edge states in the rectangular lattice, the edge states and corner states are obtained. Furthermore, the regularity between the located frequency of topological edge and corner states and the geometric parameters are discussed in detail. Finally, the rainbow trapping effects for topological edge states and corner states are investigated, respectively, in which different frequencies of topological acoustic edge and corner states are well separated and trapped in different positions without overlap. This proposal may provide a novel way for multidimensional wave manipulation and the integration of multifunctional acoustic devices.
{"title":"Multidimensional Rainbow Trapping of Sound in the Second‐Order Topological Sonic Crystals","authors":"Jiu‐Jiu Chen, Qiu‐Shuang Yang, Shao‐Yong Huo, Chun‐Ming Fu","doi":"10.1002/pssb.202400200","DOIUrl":"https://doi.org/10.1002/pssb.202400200","url":null,"abstract":"Topological rainbow trapping, which can separate and trap different frequencies of topological states into different positions, plays a key role in topological acoustic devices. However, few schemes have been proposed to realize multidimensional topological rainbow trapping effects with the hierarchy of edge and corner, which has partly restricted their practical applications in multifunctional integrated acoustic devices. Herein, a tactic to realize a multidimensional topological rainbow trapping of acoustic wave with the hierarchy of edge and corner in the second‐order topological sonic crystals is proposed. Based on the designing of a self‐ordering structure to both induce the topological phases of the bulk and edge states in the rectangular lattice, the edge states and corner states are obtained. Furthermore, the regularity between the located frequency of topological edge and corner states and the geometric parameters are discussed in detail. Finally, the rainbow trapping effects for topological edge states and corner states are investigated, respectively, in which different frequencies of topological acoustic edge and corner states are well separated and trapped in different positions without overlap. This proposal may provide a novel way for multidimensional wave manipulation and the integration of multifunctional acoustic devices.","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"60 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141614189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kwangseuk Kyhm, Jong Su Kim, Heonsu Jeon, Yong‐Hoon Cho
{"title":"Compound Semiconductors","authors":"Kwangseuk Kyhm, Jong Su Kim, Heonsu Jeon, Yong‐Hoon Cho","doi":"10.1002/pssb.202400227","DOIUrl":"https://doi.org/10.1002/pssb.202400227","url":null,"abstract":"","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"191 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141614190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Detecting Strain Effects Due to Nanobubbles in Graphene Mach–Zehnder Interferometers","authors":"Nojoon Myoung, Taegeun Song, Hee Chul Park","doi":"10.1002/pssb.202470014","DOIUrl":"https://doi.org/10.1002/pssb.202470014","url":null,"abstract":"","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"1 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141614037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hezekiah B. Sawa, Melike Babucci, Jan Keller, Charlotte Platzer Björkman, Nuru R. Mlyuka, Margaret E. Samiji
Herein, ultrathin Al2O3 is investigated as a rear interface passivation layer for kesterite solar cells with F:SnO2 (FTO) back contact for potential performance improvement. On the passivation layer, a thin Mo layer is deposited to improve the FTO's ohmicity. Further, NaF is evaporated on the copper zinc tin sulfide (CZTS) precursors to create openings at the passivation layer and achieve Na‐induced benefits in the absorber. The CZTS absorbers deposited directly on the Al2O3‐coated FTO peel off, while those with Mo interlayer do not. For pure sulfide kesterite devices, the Al2O3 layer reduces the short‐circuit current density (JSC), resulting in poor device efficiency. On the other hand, significantly higher JSC is realized for mixed sulfide and selenide kesterite devices with Al2O3 passivation layer, with the current density–voltage curve suggesting a reduced barrier height at the rear interface. As a result, the efficiency is improved from 1.5% for devices without Al2O3 to 4.6% for those with Al2O3. Likewise, improved external quantum efficiency response is observed in the devices with passivation layer for backside and frontside illumination. Therefore, contribution of Al2O3 passivation layer to the performance of kesterite‐based solar cells is evident from the results of this study.
{"title":"Effects of Al2O3 Rear Interface Passivation on the Performance of Bifacial Kesterite‐Based Solar Cells with Fluorine‐Doped Tin Dioxide Back Contact","authors":"Hezekiah B. Sawa, Melike Babucci, Jan Keller, Charlotte Platzer Björkman, Nuru R. Mlyuka, Margaret E. Samiji","doi":"10.1002/pssb.202400080","DOIUrl":"https://doi.org/10.1002/pssb.202400080","url":null,"abstract":"Herein, ultrathin Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> is investigated as a rear interface passivation layer for kesterite solar cells with F:SnO<jats:sub>2</jats:sub> (FTO) back contact for potential performance improvement. On the passivation layer, a thin Mo layer is deposited to improve the FTO's ohmicity. Further, NaF is evaporated on the copper zinc tin sulfide (CZTS) precursors to create openings at the passivation layer and achieve Na‐induced benefits in the absorber. The CZTS absorbers deposited directly on the Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>‐coated FTO peel off, while those with Mo interlayer do not. For pure sulfide kesterite devices, the Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> layer reduces the short‐circuit current density (<jats:italic>J</jats:italic><jats:sub>SC</jats:sub>), resulting in poor device efficiency. On the other hand, significantly higher <jats:italic>J</jats:italic><jats:sub>SC</jats:sub> is realized for mixed sulfide and selenide kesterite devices with Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> passivation layer, with the current density–voltage curve suggesting a reduced barrier height at the rear interface. As a result, the efficiency is improved from 1.5% for devices without Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> to 4.6% for those with Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>. Likewise, improved external quantum efficiency response is observed in the devices with passivation layer for backside and frontside illumination. Therefore, contribution of Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> passivation layer to the performance of kesterite‐based solar cells is evident from the results of this study.","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"31 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141586964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
CoxMn3−xO4 (1 ≤ x ≤ 2) spinel nanoparticles synthesized through conventional coprecipitation technique exhibit the coexistence of tetragonal and cubic phases in the range of 1 ≤ x ≤ 1.5, while a pure cubic phase is observed for 1.75 ≤ x ≤ 2 at room temperature. Reduction in tetragonal phase fraction from 92 % for x = 1 to 47% for x = 1.5 is attributed to diminution of Jahn–Teller (J–T) active Mn3+ ions occupying the octahedral site of spinel lattice. X‐ray photoelectron spectroscopy confirms both +2 and +3 oxidation states for Co and Mn. Surprisingly, cubic and tetragonal phases exhibit magnetic transition, Tc1 and Tc2, corresponding to a paramagnetic to a high and low temperature ferrimagnetic state, respectively. Tetragonal phase induces high spontaneous (HSEB) and conventional (HCEB) exchange bias with unusually high vertical magnetization shift (VMS) than that of the pure cubic phase, shows maximum HCEB of 4.062 kOe for x = 1.5 and a VMS of 2.5 emu g−1 for x = 1. Such dependence of VMS and exchange bias on tetragonal to cubic phase ratio in CoxMn3−xO4 is demonstrated for the first time and interpreted based on the interaction between different arrangement of spins in tetrahedral and octahedral sublattice.
在室温下，通过传统共沉淀技术合成的 CoxMn3-xO4 (1 ≤ x ≤ 2) 尖晶石纳米粒子在 1 ≤ x ≤ 1.5 的范围内表现出四方相和立方相共存，而在 1.75 ≤ x ≤ 2 的范围内则表现出纯立方相。四方相的比例从 x = 1 时的 92% 降至 x = 1.5 时的 47%，这是因为占据尖晶石晶格八面体位点的 Jahn-Teller (J-T) 活性 Mn3+ 离子减少了。X 射线光电子能谱证实了 Co 和 Mn 的 +2 和 +3 氧化态。令人惊讶的是，立方相和四方相表现出磁性转变（Tc1 和 Tc2），分别对应于顺磁态到高温和低温铁磁态。与纯立方相相比，四方相诱导高自发（HSEB）和常规（HCEB）交换偏置，具有异常高的垂直磁化偏移（VMS），在 x = 1.5 时显示最大 HCEB 为 4.062 kOe，在 x = 1 时显示 VMS 为 2.5 emu g-1。VMS 和交换偏置对 CoxMn3-xO4 中四方相与立方相比例的这种依赖关系是首次得到证实，并基于四面体和八面体亚晶格中不同排列的自旋之间的相互作用进行了解释。
{"title":"Competition between Cubic and Tetragonal Phase Induced Unusual Vertical Magnetization Shift and Exchange Bias in CoxMn3−xO4 (1 ≤ x ≤ 2) Spinel Nanoparticles","authors":"Sanjna Rajput, Chandana Rath","doi":"10.1002/pssb.202400090","DOIUrl":"https://doi.org/10.1002/pssb.202400090","url":null,"abstract":"Co<jats:sub><jats:italic>x</jats:italic></jats:sub>Mn<jats:sub>3−<jats:italic>x</jats:italic></jats:sub>O<jats:sub>4</jats:sub> (1 ≤ <jats:italic>x</jats:italic> ≤ 2) spinel nanoparticles synthesized through conventional coprecipitation technique exhibit the coexistence of tetragonal and cubic phases in the range of 1 ≤ <jats:italic>x</jats:italic> ≤ 1.5, while a pure cubic phase is observed for 1.75 ≤ <jats:italic>x</jats:italic> ≤ 2 at room temperature. Reduction in tetragonal phase fraction from 92 % for <jats:italic>x</jats:italic> = 1 to 47% for <jats:italic>x</jats:italic> = 1.5 is attributed to diminution of Jahn–Teller (J–T) active Mn<jats:sup>3+</jats:sup> ions occupying the octahedral site of spinel lattice. X‐ray photoelectron spectroscopy confirms both +2 and +3 oxidation states for Co and Mn. Surprisingly, cubic and tetragonal phases exhibit magnetic transition, Tc<jats:sub>1</jats:sub> and Tc<jats:sub>2</jats:sub>, corresponding to a paramagnetic to a high and low temperature ferrimagnetic state, respectively. Tetragonal phase induces high spontaneous (H<jats:sub>SEB</jats:sub>) and conventional (H<jats:sub>CEB</jats:sub>) exchange bias with unusually high vertical magnetization shift (VMS) than that of the pure cubic phase, shows maximum H<jats:sub>CEB</jats:sub> of 4.062 kOe for <jats:italic>x</jats:italic> = 1.5 and a VMS of 2.5 emu g<jats:sup>−1</jats:sup> for <jats:italic>x</jats:italic> = 1. Such dependence of VMS and exchange bias on tetragonal to cubic phase ratio in Co<jats:sub><jats:italic>x</jats:italic></jats:sub>Mn<jats:sub>3−<jats:italic>x</jats:italic></jats:sub>O<jats:sub>4</jats:sub> is demonstrated for the first time and interpreted based on the interaction between different arrangement of spins in tetrahedral and octahedral sublattice.","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"57 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141588571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Crystals of the family of tetragonal, non‐centrosymmetric melilites have attracted interest as nonlinear optical, piezoelectric, and ferroelectric materials. This work presents an ab initio study of the optical properties of europium melilite, Eu2MgSi2O7. The study includes the calculation of refractive and absorption spectra, with respect to the density of states of the system. The obtained results demonstrate the correlation between the electronic structure of europium melilite and its optical characteristics.
{"title":"Nonlinear Optical Effects in Europium Melilite Eu2MgSi2O7","authors":"Kseniya Mikhailovna Tsysar, Dmitry Igorevich Bazhanov, Karine Karlenovna Abgaryan, Nadezhda Nikolaevna Kiselyova","doi":"10.1002/pssb.202400172","DOIUrl":"https://doi.org/10.1002/pssb.202400172","url":null,"abstract":"Crystals of the family of tetragonal, non‐centrosymmetric melilites have attracted interest as nonlinear optical, piezoelectric, and ferroelectric materials. This work presents an ab initio study of the optical properties of europium melilite, Eu<jats:sub>2</jats:sub>MgSi<jats:sub>2</jats:sub>O<jats:sub>7</jats:sub>. The study includes the calculation of refractive and absorption spectra, with respect to the density of states of the system. The obtained results demonstrate the correlation between the electronic structure of europium melilite and its optical characteristics.","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"16 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141570462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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