c-axis-oriented SmBa2Cu3O7（SmBCO） films have been deposited on（100）- LaA1O3（LAO）substrate by metal organic chemical vapor deposition（MOCVD） technique.The effects of deposition temperature（T（dep）） and total...c-axis-oriented SmBa2Cu3O7（SmBCO） films have been deposited on（100）- LaA1O3（LAO）substrate by metal organic chemical vapor deposition（MOCVD） technique.The effects of deposition temperature（T（dep）） and total pressure（P（tot）） on the orientation and microstructure of SmBCO films were investigated.The orientation of SmBCO films transformed from α-axis to c-axis with increasing of T（dep） from 900 to 1 100℃.At T（dep）=1 050℃,SmBCO films had c-axis orientation and tetragon surface.At P（tot）^（dep）=400-800 Pa and T（dep）=1 050 ℃,totally c-axis-oriented SmBCO films were obtained.The R（dep） of SmBCO films increased firstly and then decreased with increasing P（tot）.The surface of SmBCO films exhibited tetragon morphology at 1 050 ℃ and400 Pa.Maximum thickness of SmBCO film deposited was 1.2μm at P（tot）= 600 Pa,and the corresponding R（dep）was 7.2 μm·h^（-1）.展开更多
The homogeneity of the microstructure and composition are critical in determining the properties of rare earthbarium‐cuprate,single grain bulk superconductors[(RE)BCO].The magnitude of the trapped magnetic field achi...The homogeneity of the microstructure and composition are critical in determining the properties of rare earthbarium‐cuprate,single grain bulk superconductors[(RE)BCO].The magnitude of the trapped magnetic field achieveable in these technologically important materials,in particular,is influenced heavily by the size and distribution of(RE)_(2)BaCuO_(x)(RE‐211)flux pinning inclusions in the bulk microstructure,whereas the size and distribution of silver agglomerates present within the bulk superconducting matrix correlate directly with improved mechanical properties.With careful engineering,these materials have significant potential for application in range of devices related to energy storage,medicine,electro‐magnetic machinery and microelectronic technology.Fabrication of(RE)BCO bulk superconductors typically involves heating a powder compact above its peritectic decomposition temperature followed by slow cooling to facilitate the growth of a single grain.Each(RE)BCO composition has a different peritectic temperature and growth rate,which,therefore,necessitates different requirements in the heating profile.The fabrication temperature and growth rate,for example,may have an effect on the RE‐211 and silver distribution,which may,in turn,affect the superconducting properties of the resulting single grain.In this work we compare the distributions of silver and RE‐211 in the single grain microstructures of YBCOAg,GdBCO‐Ag,EuBCO‐Ag and SmBCO‐Ag bulk superconductors using optical microscopy,scanning electron microscopy and energy dispersive X‐ray spectroscopy.We observe that the distributions are very similar along both the a/b‐axis and c‐axis of these materials.This suggests that factors other than the maximum temperature used to achieve peritectic decomposition and the rate of single grain growth are particularly influential in determining the properties of the as‐processed samples in the top seeded melt growth process.This observation demonstrates there is freedom to use(RE)materials interchangeably between different applications as required,for example,for functional or economic reasons.展开更多
基金Funded by National Natural Science Foundation of China(Nos.51102101,51272196,51372188,51521001)the 111 Project(No.B13035)+2 种基金International Science&Technology Cooperation Program of China(No.2014DFA53090)the Natural Science Foundation of Hubei Province,China(No.2014CFB870)the Fundamental Research Funds for the Central Universities,China(No.WUT:2015III023)
文摘c-axis-oriented SmBa2Cu3O7（SmBCO） films have been deposited on（100）- LaA1O3（LAO）substrate by metal organic chemical vapor deposition（MOCVD） technique.The effects of deposition temperature（T（dep）） and total pressure（P（tot）） on the orientation and microstructure of SmBCO films were investigated.The orientation of SmBCO films transformed from α-axis to c-axis with increasing of T（dep） from 900 to 1 100℃.At T（dep）=1 050℃,SmBCO films had c-axis orientation and tetragon surface.At P（tot）^（dep）=400-800 Pa and T（dep）=1 050 ℃,totally c-axis-oriented SmBCO films were obtained.The R（dep） of SmBCO films increased firstly and then decreased with increasing P（tot）.The surface of SmBCO films exhibited tetragon morphology at 1 050 ℃ and400 Pa.Maximum thickness of SmBCO film deposited was 1.2μm at P（tot）= 600 Pa,and the corresponding R（dep）was 7.2 μm·h^（-1）.
基金support from the Engineering and Physical Sciences Research Council(EPSRC)grant EP/T014679/1.
文摘The homogeneity of the microstructure and composition are critical in determining the properties of rare earthbarium‐cuprate,single grain bulk superconductors[(RE)BCO].The magnitude of the trapped magnetic field achieveable in these technologically important materials,in particular,is influenced heavily by the size and distribution of(RE)_(2)BaCuO_(x)(RE‐211)flux pinning inclusions in the bulk microstructure,whereas the size and distribution of silver agglomerates present within the bulk superconducting matrix correlate directly with improved mechanical properties.With careful engineering,these materials have significant potential for application in range of devices related to energy storage,medicine,electro‐magnetic machinery and microelectronic technology.Fabrication of(RE)BCO bulk superconductors typically involves heating a powder compact above its peritectic decomposition temperature followed by slow cooling to facilitate the growth of a single grain.Each(RE)BCO composition has a different peritectic temperature and growth rate,which,therefore,necessitates different requirements in the heating profile.The fabrication temperature and growth rate,for example,may have an effect on the RE‐211 and silver distribution,which may,in turn,affect the superconducting properties of the resulting single grain.In this work we compare the distributions of silver and RE‐211 in the single grain microstructures of YBCOAg,GdBCO‐Ag,EuBCO‐Ag and SmBCO‐Ag bulk superconductors using optical microscopy,scanning electron microscopy and energy dispersive X‐ray spectroscopy.We observe that the distributions are very similar along both the a/b‐axis and c‐axis of these materials.This suggests that factors other than the maximum temperature used to achieve peritectic decomposition and the rate of single grain growth are particularly influential in determining the properties of the as‐processed samples in the top seeded melt growth process.This observation demonstrates there is freedom to use(RE)materials interchangeably between different applications as required,for example,for functional or economic reasons.
