The rapid developments of Science and Technology call for individuals to have strong academic knowledge and creativity. Research shows that students acquire creativity after either curricular or extracurricular activities in subject matters. However, there is not much research examining students’ creativity through integrative learning activities, such as STEM activities. In this current study, we examine the potential of STEM clubs in terms of fostering students’ creativity. We used the survey method to assess students’ creativity in engineering design. We collected the data from 244 Vietnamese students, including members and non-members in STEM clubs. The quantitative analysis was performed to examine the differences between members’ creativity and non-members’ creativity. The results show that STEM club members have significantly more creativity than non-members. The results also show that STEM club members have significantly more creativity than non-members. Based on the results, STEM clubs demonstrate a significant impact on students' creativity. Consequently, STEM clubs should be implemented in high school to enhance students’ creativity.

Superconductors application can lead to significant economic benefits, especially in combination with use of liquid hydrogen, which is becoming an important part of the renewable energy economy. While many traditional superconductors cannot operate in liquid hydrogen, new materials, like high-temperature superconductors and MgB2 perfectly suit this purpose. YBa2Cu3Ox is one of the most used high-temperature superconductors. It can operate even in liquid nitrogen, at the temperature of 77.3 K, but has a strong advantage of enhanced critical current density at the boiling temperature of liquid hydrogen of 20 K. A disadvantage of this material is the absence of natural c-axis pinning centers defining its critical current density. A usual way to solve this problem is the introduction of artificial pinning centers in the form of nanoparticles. The nanoparticles, however, reduce the volume of the superconductor and can lead to the formation of high-angle grain boundaries detrimental for the critical current. Here we explore an approach of depositing magnetic nanoparticles on the surface of superconducting films, which neither reduce the volume of the superconductor nor create high-angle grain boundaries. The additional pinning by these nanoparticles is studied by recording magneto-optical images of the films.

We have grown, by Pulsed Laser Deposition (PLD), a large number of YBa2Cu3O7 films with artificial pinning centers, with various impurities, various architectures and thickness, and various techniques of nano-scale pinning engineering: substrate decoration, BaZrO3 (BZO) nano-inclusions, and (quasi) multilayer architecture. Here we will present the results regarding vortex matter, dynamics, and pinning, in some of our best samples. Magnetic relaxation studies with magnetic field perpendicular to the film show that in both cases the splayed defects and/or nanoscale inclusions help reduce the dissipation in certain field-temperature range, by inhibiting the detrimental double vortex-kink formation. The response of the vortex system to AC excitation is rather complex but extremely useful for the characterization of the vortex dynamics. We have measured AC susceptibility in various DC fields, with various AC fields and frequencies and found that the effective vortex activation energy [Formula: see text] has a logarithmic dependence on the AC-field-induced current density [Formula: see text]. Synergetic pinning centers assured a low anisotropy of the critical current for various field orientations, a property desired in coil/solenoid applications.

We report an unusual effect of channeled magnetic flux motion in YBa2Cu3O7−δ/PrBa2Cu3O7−δ superlattices grown by pulsed laser deposition. Magneto-optical imaging reveals that flux moves along a set of parallel and perpendicular lines, while optical microscopy does not show any features on the surface that may cause this effect. In contrast, scanning electron microscopy registers sub-micron fractures in the superlattices, corresponding to the flux lines, but the magnetic flux channels are much wider than the width of these fractures. To further clarify the origin of flux channels, electrical transport measurements on the superlattices have been performed. Their current-voltage characteristics reveal the presence of distinctive branches related to the flux motion along the selective channels, following which magnetic flux can cross the sample in a shortest and least resistive way. The application of very large current overheated the superlattice along these channels evaporating superconducting material and exposing wider than in the superconductor fractures in the substrate. It is concluded that motion of flux in the channels is controlled not only by the presence of nano-fractures in YBa2Cu3O7−δ/PrBa2Cu3O7−δ, but also stresses developed in the superconducting material appearing due to the fracturing of the substrate.

The colloidal silver solution was synthesized by reducing silver nitrate () using sodium borohydride () and starch as a stabilizer agent. The size and optical properties of synthesized AgNPs were characterized by UV-Vis spectroscopy, Fourier transform-infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The effects of several parameters on AgNPs were also investigated. The results have shown that the size of synthesized spherical silver nanoparticles was and disperse in water. The synthesized AgNPs of his study exhibited a strong antibacterial activity against Gram-negative bacteria Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus). The average zones of inhibition of AgNPs were of 7.7 mm for bacteria E. coli and 7.0 mm for S. aureus. In this study, the zone of inhibition of AgNPs was also compared to the reference antibiotics drug.

We report unusual effect of channeled magnetic flux motion in YBa 2 Cu 3 O 7-δ /PrBa 2 Cu 3 O 7-δ superlattices grown by pulsed laser deposition. Magneto-optical imaging reveals that flux moves along a set of parallel and perpendicular lines, while optical microscopy does not show any features on the surface that may be linked to this effect. In contrast, scanning electron microscopy registers sub-micron fractures in the superlattices corresponding to these flux lines, but the magnetic flux channels are much wider than the width of these fractures. To further clarify the origin of flux channels, electrical transport measurements on the superlattices have been performed. Their current-voltage characteristics reveal the presence of distinctive branches related to the flux motion along the selective channels, following which magnetic flux crosses sample in a shortest and least resistive way. The application of very large current overheated the superlattice along these channels, evaporating superconducting material and exposing, wider than in the superconductor, fractures in the substrate. It is concluded that motion of flux in the channels is controlled not only by the presence of nano-fractures in YBa 2 Cu 3 O 7-δ /PrBa 2 Cu 3 O 7-δ , but also by stress developed in the superconducting material due to the fracturing of the substrate.

We report on the enhancement of critical current density (J(c)) and the unusual behaviour of its dependence on field orientation in YBa2Cu3O7-x (YBCO) nanostructured films by a combination of substrate decoration with Ag nano-dots, of the incorporation of BaZrO3 (BZO) nano-particles and nano-rods, and of multilayer architecture (a thin SrTiO3 layer separating two 1.5 mu m-thick YBCO layers). SrTiO3 insulating layers were 15, 30 or 45 nm thick. The highest improvement of J(c) in applied magnetic fields along the c-axis and smaller than 1 T occurs in the bi-layer with 30 nm-thick STO, but the influence of STO thickness is small. Our thick nanostructured films show significant improvement of J(c) in the magnetic field along the ab-plane direction. The presence of BZO nano-rods, ab-plane defects and nano particles of BZO and Y2O3 was observed in transmission electron microscopy (TEM) images of the film. The peculiarities of artificial pinning centres revealed in the TEM images of the nanostructured films are used to explain an unusual split of the peak in the J(c) dependence on the magnetic field along the ab-plane of YBCO. Effective pinning potentials in high magnetic fields have rather high values for such thick films.

For practical applications of superconducting materials in applied magnetic fields, artificial pinning centres in addition to natural ones are required to oppose the Lorentz force. These pinning centres are actually various types of defects in the superconductor matrix. The pinning centres can be categorised on their dimension (volume, surface or point) and on their character (normal cores or Δκ cores). Different samples have been produced by Pulsed Laser Deposition, with various thicknesses, temperatures and nanostructured additions to the superconducting matrix. They have been characterized by SQUID Magnetic Properties Measurement System and Physical Properties Measurement System, as well as by Transmission Electron Microscopy (TEM). Correlations between pinning architecture, TEM images, and critical currents at various fields and field orientations will be shown for a large number of YBa2Cu3Ox films with various types and architectures of artificial pinning centres.

A new titanium precursor, [Ti(OPri)2(deacam)2] (deacam = N,N‐diethylacetoacetamide), was developed by the reaction of the parent Ti alkoxide with the β‐ketoamide. The compound, obtained as a monomeric six‐coordinated complex, was used in metal organic chemical vapor deposition (MOCVD) of TiO2 both as a single source precursor (SSP) and in the presence of oxygen. The high thermal stability of [Ti(OPri)2(deacam)2] enabled the fabrication of TiO2 films over a wide temperature range, with steady growth rates between 500 and 800 °C. The microstructure of the obtained systems was analyzed by X‐ray diffraction (XRD) and Raman spectroscopy, whereas atomic force microscopy (AFM) and field emission‐scanning electron microscopy (FE‐SEM) measurements were performed to investigate the surface morphology and nanoorganization. Film composition was investigated by complementary techniques like Rutherford backscattering spectrometry (RBS), nuclear reaction analysis (NRA), X‐ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS). The electrical properties of the layers were investigated by performing capacitance voltage (C–V) and leakage current measurements.

Thin films of Y2O3 are deposited on Si(100) and Al2O3 (0001) substrates via metal‐organic (MO)CVD for the first time using two closely related yttrium tris‐amidinate compounds as precursors in the presence of oxygen in the temperature range 400–700 °C. The structural, morphological, and compositional features of the films are investigated in detail. At deposition temperatures of 500 °C and higher both the precursors yield polycrystalline Y2O3 thin films in the cubic phase. The compositional analysis revealed the formation of nearly stoichiometric Y2O3. The optical band gaps are estimated using UV‐Vis spectroscopy. Preliminary electrical measurements are performed in the form of a metal oxide semiconductor (MOS) structure of Al/Y2O3/p‐Si/Ag. Leakage currents and dielectric constants are also determined.

Metalorganic chemical vapor deposition (MOCVD) of nanostructured Er2O3 thin films was performed using the Er-tris-guanidinate precursor [Er(DPDMG)3] (DPDMG = diisopropyl-2-dimethylamidoguanidinato) as the Er source and oxygen. Film deposition was carried out on Si(100) and quartz glass substrates and the process parameters namely temperature, pressure and oxygen flow rate were varied. The resulting thin films were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) for investigating the crystallinity and morphology, respectively. The chemical composition of the film was investigated by X-ray photoelectron spectroscopy (XPS) measurements. Transmittance and absorption spectra of the 600 degrees C film grown on glass substrates were performed by UV-vis measurements revealing more than 80% transmittance. The potential of Er2O3 thin films as gate dielectrics was verified by carrying out capacitance-voltage (C-V) and current-voltage (I-V) measurements. Dielectric constants estimated from the accumulation capacitance were found to be in the range of 10-12 in AC frequencies of 1 MHz down to 10 kHz and the leakage current of the order of 2 x 10(-8) A/cm2 at the applied field of 1 MV cm(-1) was measured for films deposited under optimised process conditions. The low leakage current and high dielectric constant implies good quality of the Er2O3 layers relevant for high-k applications. These layers were found to be paramagnetic with a slightly reduced magnetic moment of the Er3+ ions.

Metal‐organic (MO)CVD of ZrO 2 thin films is performed using the precursor [Zr(NMe 2 ) 2 (guan) 2 ] (guan = η 2 ‐( i PrN) 2 CNMe 2 ) as the Zr source, together with oxygen. Film deposition is carried out on both Si(100) and glass substrates at various deposition temperatures. The resulting films are characterized by X‐ray diffraction (XRD) and atomic force microscopy (AFM) for investigating the crystallinity and morphology, respectively. Optical properties are measured by ellipsometry and UV‐vis on Si substrates and glass substrates, respectively, showing a high average refractive index of 2.14 and transmittance of more than 80% in visible light for the film deposited at 500°C. The potential of ZrO 2 thin films as gate dielectrics is verified by carrying out capacitance‐voltage ( C ‐ V ) and current‐voltage ( I ‐ V ) measurements. Dielectric constants are estimated from the accumulation capacitance, and found to be in the range 12 ‐ 19 at an AC frequency of 1 MHz, and a leakage current of the order of 10 −6 A cm −2 at the applied field of 1 to 2 MV cm −1 is measured for the films deposited at temperatures from 500 to 700°C. The low leakage current and high dielectric constant implies the good quality of the film, relevant for high‐ k applications. The hardness of the film ranges from 4.2 to 6.3 GPa for the 400 nm thick film, as determined by nano‐indentation measurements. The optimum dielectric and hardness is found for the film deposited at 600°C, while the highest refractive index is found to be 2.14 for the film deposited at 500°C, due to higher density of the layers.

We report on the electrical and optical characterisation of the high‐permittivity (high‐κ) TiO2 thin films grown by plasma enhanced atomic layer deposition on Si (100) and glass substrates, respectively. TiO2 films were incorporated in metal‐oxide semiconductor (MOS) capacitor structures with an Al metal gate electrode. The as‐deposited films were amorphous; however upon annealing in the temperature range 500–900 °C, crystalline TiO2 in the anatase phase was formed. This was further confirmed by performing Raman measurements where the characteristic features corresponding to the anatase phase were observed. Transmittance and absorption spectra of the as‐deposited and annealed films were performed by UV–Vis measurements showing more than 70% of transmittance. The formation of stoichiometric TiO2 was revealed by X‐ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectroscopy (RBS) analysis performed on annealed samples (500–900 °C). The dielectric constants were calculated from capacitance–voltage (C–V) curves of the MOS structure on the as‐deposited film and annealed films revealing a significant improvement of the dielectric constants from 10 to 75 at AC frequencies of 100 kHz for the 700 °C annealed TiO2 thin films. The increase in the dielectric constant for annealed films could be attributed to the transformation of film structure from amorphous to polycrystalline (anatase). However, the transformation of amorphous to crystalline phase, leads to an increase in the leakage current which was also found best fitted with Schottky emission mechanism at moderated electric fields.

A new heteroleptic titanium precursor with a mixed oxygen/nitrogen coordination sphere [Ti(dmap)2(NMe2)2] (Hdmap = 1–dimethylamino–2–propanol) is synthesized by a simple elimination reaction on tetrakis–dimethylaminotitanium(IV) [Ti(NMe2)4]. The compound shows encouraging results in terms of chemical and thermal stability compared to the parent alkyl amide [Ti(NMe2)4], and is therefore more suitable for MOCVD applications. TiO2 thin films are grown on Si(100) and ITO‐coated borosilicate glass substrates via MOCVD in the temperature range 500–800°C. The deposition temperature has a significant effect on the phase and microstructure of the TiO2 films obtained, which influences the functional properties. The optical bandgaps of the films are in the range 2.92–3.36 eV. The best photocurrent response (1.5 mA cm−2 under AM 1.5G conditions) in aqueous electrolytes is observed for films grown at 700°C having improved crystallinity and porous columnar structure.

The Bose glass theory for the vortex matter in superconductors with correlated disorder predicts the depinning of vortices due to the renormalization of the vortex pinning barriers by thermal fluctuations. For YB2Cu3O7 (YBCO) in external magnetic fields H oriented along the columnar pins generated by various techniques theoretical estimates give a depinning temperature T dp very close to the critical temperature T c (T dp∼0.95T c), whereas the results of standard magnetization relaxation experiments are repeatedly interpreted in terms of a much lower T dp (∼0.5T c). We investigated the temperature T variation of the normalized magnetization relaxation rate S for YBCO thin films containing BaZrO3 (BZO) nanorods preferentially oriented along the c axis, with H along the nanorods. The nonmonotonous S(T) variation below the matching field observed up to close to T c does not support a low T dp. The often considered S(T) maximum occurring at relatively low T (which was connected to a disappointing T dp) is related to the occurrence of thermomagnetic instabilities. We show that the accommodation of vortices to the columnar pins in the presence of the T dependent macroscopic currents induced in the sample is signaled by a pronounced S(T) deep located at high T, in agreement with a T dp close to T c. By increasing the film thickness and using the substrate decoration the BZO nanorods splay out, leading to the inhibition of (detrimental) vortex excitations involving double vortex kink or superkink formation, characteristic for high-quality thin films and single crystals with columnar pins along the c axis.

The second-generation coated tapes of high temperature superconductors (HTS) deposited on textured metal substrates strongly rely on the introduction of extended nano-defects in order to enhance their critical current. A proven effective way to introduce such defects is growing BaZrO3 (BZO) nano-rods and an alternative way is to generate HTS columnar growth using nanoparticles of noble metals. Here we report the combination of these methods. It allows achieving controlled pinning and high critical current in YBa2Cu3Ox films deposited on single crystal substrates and significantly improves critical current in coated conductors deposited on rolling-assisted biaxially-textured metal substrates (RABiTS). The superconducting properties of thick (up to 5 micron) conductors are analysed using DC-magnetisation, AC-susceptibility and angle-dependent transport measurements. TEM imaging is used to confirm the presence of extended defects in the tapes.

We report on an original technique for nanoengineered pinning centers that combine three previously reported approaches: substrate decoration, quasi-multilayers and targets with secondary phase nanoinclusions. We have used a 4% BZO-doped YBCO target, and Ag nanodots, all grown by PLD. Such an approach gave interesting results in terms of pinning landscape, as proved by TEM studies. Angle-dependent measurements of critical current I-c showed that, for smaller fields, the absolute maximum in I-c occur for fields perpendicular to the a-b planes, while at larger fields the absolute maximum in I-c occurs for fields parallel to the a-b planes, in both cases with a clear second, local maxima. Measurements also showed a smooth change in the character of pinning with magnetic field, from the out-of-plane to in-plane-dominant pinning. For the out-of-plane magnetic field, the highest Ic-w (critical current per cm width) obtained so far, at 77.3 K, occurred in a 5.8 mu m Ag nanodots / BZO-doped YBCO trilayer: 782 A/cm-w in self-field, 167 A/cm-w in 1 T and 18 A/cm-w in 3 T.