Dual magnetron sputter deposition of yttria-stabilized zirconia thin films

Driven by the global quest for alternative materials, several initiatives have been started to develop better materials to be applicable not only in research but also in industry. There are two possible ways to obtain these materials. The first comprises the discovery of a new material, while the second involves the understanding of the behavior of an existing material in order to control its characteristics. Due to the strong driving force towards creation of new technologies, up to now more effort has been done in the development of new materials, leaving the understanding to a side. This research focuses on Yttria-stabilized Zirconia (YSZ), which is commonly known as solid electrolytes. These types of electrolytes are electrically conductive materials due to the presence of mobile ions acting as charge carrier. The charge carrier can be a cation (such as H+, Li+, Ag+) or an anion (such as F− and O2−). A vast amount of literature data on these materials is mostly related to bulk materials and thick films. However, there is at present a limited amount of information on the fundamental aspects related to solid state electrolytes on academic level, specially in Flanders. Nevertheless, this fundamental research is needed to support the idea of understanding the material in order to control its properties. In order to discern the relations happening in the solid state electrolyte, it is necessary to reduce its proportions to atomic level. Downscaling the electrolytes to thin films, for example, changes their fundamental aspects due to the occurrence of small scale or nano effects. Essentially, two fundamental questions arise when reducing the film thickness. First, one can question if the results related to the influence of the composition on the ion conductivity as measured for bulk solid state electrolytes can be transferred to thin film materials. The pronounced scatter of the activation energies for the oxygen ion migration and electrical conductivity properties of solid state electrolytes as a function of their composition makes it difficult to answer this question. The second question is related to microstructure and crystallinity. At present, it is not clear how the microstructure of solid state electrolytes affects the properties of the thin films. However, a good understanding of this relationship would open the possibility to manipulate the YSZ properties by controlling the nanocrystalline microstructure of the thin film. Naturally, one must realize that this subdivision based on these two questions is somewhat artificial as the thin film morphology and texture can be related to the composition. Hence, only a multi-axis approach allows a full understanding due to the relationship between composition and microstructure (and texture). Therefore, it is necessary to investigate the morphological and textural characteristics of thin films as function of both composition and deposition conditions. In this way, the three principal axes are i) elemental composition, ii) microstructure and texture and, iii) properties

Development and test of resistive superconducting fault current limiter; acting time and its recovery conditions

Resistive-type of superconducting fault current limiters (RSFCL) have been developed for medium voltage class aiming to operate at 1 MVA power capacity and short time recovery (< 2 s). A RSFCL in form of superconducting modular device was designed and constructed using 50 m-length of YBCO coated conductor tapes for operation under 1 kV / 1 kA and acting time of 0.1 s. In order to increase the acting time the RSFCL was combined with an air-core reactor in parallel to increase the fault limiting time up to 1 s. The tests determined the electrical and thermal characteristics of the combined resistive/ inductive protection unit. The combined fault current limiter reached a limiting current of 583 A, corresponding to a limiting factor of 3.3 times within an acting time of up to 1 s

Modeling and experiment of the current limiting performance of a resistive superconducting fault current limiter in the experimental system

In this paper, a 220-V resistive superconducting fault current limiter (SFCL) prototype is built and tested under different prospective fault currents, which vary from 0.8 to 7.4 kA. A 2D superconductor model is integrated into an experimental circuit model in COMSOL to simulate the performance of the SFCL prototype in the experimental system in fault tests. In the simulation, a new E-J relationship is proposed to enhance the convergence of calculation. Comparison between simulation results and experimental results shows that the proposed model performs well in simulating current limiting performance of SFCL in experimental system in case of fault.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Project and construction of a fault current limiter using YBCO tapes

Limitadores de corrente supercondutores resistivos (LCSR) são dispositivos com características elétricas próximas ao ideal quando ocorre a transição do estado supercondutor para o estado normal, limitando a corrente de falta através da inserção rápida de uma resistência na rede. A viabilidade técnica e econômica destes limitadores aumentou após o desenvolvimento dos supercondutores de alta temperatura crítica HTS. A primeira geração de fitas HTS (BSCCO) consiste em multifilamentos de material supercondutor embutidos em uma matriz de prata. A densidade de corrente crítica típica é de aproximadamente 140 A/mm2. Contudo, a resistência alcançada pelo LCSR quando atinge o estado normal não é suficiente para limitar a corrente de falta, sendo necessários longos comprimentos de fitas (~5 km) para que a corrente seja limitada. O recente desenvolvimento de fitas supercondutoras de YBCO com filmes finos texturizados e com substrato de alta resistividade superou o desempenho das fitas de BSCCO para esta aplicação. Com uma densidade de corrente crítica de 136 A/mm2, as fitas de YBCO são bem conhecidas pelo seu alto valor de índice n (aproximadamente 30), rápida resposta de transição após falta e alta resistência elétrica no estado normal. Neste trabalho foram analisados o comportamento elétrico e magnético das fitas de BSCCO e YBCO (em amostras curtas de 0,2 m) utilizando diferentes técnicas de caracterização das propriedades das fitas HTS. A partir destes resultados, medidas com pulsos de corrente DC e AC com intensidades de 3 a 7 vezes a corrente crítica do sistema (I=720 A a 1700 A) com duração de 1 a 5 ciclos da rede em 60 Hz (16 a 80 ms) foram realizados de forma a obter as características do tempo de recuperação em um elemento contendo 4 fitas em paralelo (0,4 m). Os resultados permitiram o projeto, construção e medidas em corrente AC de um protótipo LCSR (Ipico = 2 kA) contendo 16 elementos sob condições normais de operação da rede (220 V - 60 Hz).Resistive Superconducting fault current limiter (SFCL) are devices with electrical behavior near the ideal when it changes its state from the superconducting to the normal state, limiting the fault current by the insertion of a fast transition resistance in the grid. The technical and economical feasibility of these limiters arose after the development of the high critical temperature superconductors HTS. First generation HTS tapes (BSCCO) consist of multifilamentary composite tapes embedded in a silver matrix. The typical critical current density is approximately 14 kA/cm2. However, the resistance reached by the SFCL when normal state occurs is not high enough to limit the fault current, making necessary long lengths of tapes (~5 km) for limiting purposes. The recently development of coated conductors composites with high resistivity metal substrate have succeeded the BSCCO tapes which are based on YBCO textured film. Upon carrying a critical current density of 13.6 kA/cm2, YBCO tapes are well known for their high n-index value (approximately 30), fast transition response after fault, and high electrical resistance in the normal state. In this work, we will present the electrical and magnetic performance of BSCCO and YBCO tapes (short samples of 0.2 m) using several techniques to characterize the properties of the HTS tapes. It was also performed analysis with DC and AC currents peaks with strength of 3 to 7 times the critical current (I=720 A to 1700 A) lasting 1 to 5 cycles (16 to 80 ms) in order to verify the recovery characteristics in an element with 4 tapes in a parallel connection. And with those characteristics we designed and constructed and measured in AC current a SFCL prototype (Ipeak = 2 kA) consisting in 16 elements to use in the grid (220 V - 60 Hz) under operational conditions

Project and construction of a fault current limiter using YBCO tapes

Limitadores de corrente supercondutores resistivos (LCSR) são dispositivos com características elétricas próximas ao ideal quando ocorre a transição do estado supercondutor para o estado normal, limitando a corrente de falta através da inserção rápida de uma resistência na rede. A viabilidade técnica e econômica destes limitadores aumentou após o desenvolvimento dos supercondutores de alta temperatura crítica HTS. A primeira geração de fitas HTS (BSCCO) consiste em multifilamentos de material supercondutor embutidos em uma matriz de prata. A densidade de corrente crítica típica é de aproximadamente 140 A/mm2. Contudo, a resistência alcançada pelo LCSR quando atinge o estado normal não é suficiente para limitar a corrente de falta, sendo necessários longos comprimentos de fitas (~5 km) para que a corrente seja limitada. O recente desenvolvimento de fitas supercondutoras de YBCO com filmes finos texturizados e com substrato de alta resistividade superou o desempenho das fitas de BSCCO para esta aplicação. Com uma densidade de corrente crítica de 136 A/mm2, as fitas de YBCO são bem conhecidas pelo seu alto valor de índice n (aproximadamente 30), rápida resposta de transição após falta e alta resistência elétrica no estado normal. Neste trabalho foram analisados o comportamento elétrico e magnético das fitas de BSCCO e YBCO (em amostras curtas de 0,2 m) utilizando diferentes técnicas de caracterização das propriedades das fitas HTS. A partir destes resultados, medidas com pulsos de corrente DC e AC com intensidades de 3 a 7 vezes a corrente crítica do sistema (I=720 A a 1700 A) com duração de 1 a 5 ciclos da rede em 60 Hz (16 a 80 ms) foram realizados de forma a obter as características do tempo de recuperação em um elemento contendo 4 fitas em paralelo (0,4 m). Os resultados permitiram o projeto, construção e medidas em corrente AC de um protótipo LCSR (Ipico = 2 kA) contendo 16 elementos sob condições normais de operação da rede (220 V - 60 Hz).Resistive Superconducting fault current limiter (SFCL) are devices with electrical behavior near the ideal when it changes its state from the superconducting to the normal state, limiting the fault current by the insertion of a fast transition resistance in the grid. The technical and economical feasibility of these limiters arose after the development of the high critical temperature superconductors HTS. First generation HTS tapes (BSCCO) consist of multifilamentary composite tapes embedded in a silver matrix. The typical critical current density is approximately 14 kA/cm2. However, the resistance reached by the SFCL when normal state occurs is not high enough to limit the fault current, making necessary long lengths of tapes (~5 km) for limiting purposes. The recently development of coated conductors composites with high resistivity metal substrate have succeeded the BSCCO tapes which are based on YBCO textured film. Upon carrying a critical current density of 13.6 kA/cm2, YBCO tapes are well known for their high n-index value (approximately 30), fast transition response after fault, and high electrical resistance in the normal state. In this work, we will present the electrical and magnetic performance of BSCCO and YBCO tapes (short samples of 0.2 m) using several techniques to characterize the properties of the HTS tapes. It was also performed analysis with DC and AC currents peaks with strength of 3 to 7 times the critical current (I=720 A to 1700 A) lasting 1 to 5 cycles (16 to 80 ms) in order to verify the recovery characteristics in an element with 4 tapes in a parallel connection. And with those characteristics we designed and constructed and measured in AC current a SFCL prototype (Ipeak = 2 kA) consisting in 16 elements to use in the grid (220 V - 60 Hz) under operational conditions