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Nowadays, the technical advances call for efficient electromagnetic interference (EMI) shielding of transparent devices which may be subject to data theft. We developed Cu–Ag and Ni–Ag meshes on flexible PET substrate for highly efficiency transparent EMI shielding coating. Cu–Ag and Ni–Ag meshes obtained with galvanic deposition of copper and nickel on thin Ag seed mesh which was made by cracked template method. Coefficients S11, S21 and shielding efficiency (SE) were measured for Cu–Ag and Ni–Ag meshes in X-band (8–12 GHz) and K-band (18–26.5 GHz). 90 s copper deposition increase SE from 23.2 to 43.7 dB at 8 GHz with a transparency of 82.2% and a sheet resistance of 0.25 Ω/sq. The achieved maximum SE was 47.6 dB for Cu–Ag mesh with 67.8% transparency and 41.1 dB for Ni–Ag mesh with 77.8% transparency. Cu–Ag and Ni–Ag meshes have high bending and long-term stability. Minimum bend radius is lower than 100 µm. This effect allows to produce different forms of transparent shielding objects, for example, origami method. Our coatings are the leading among all literary solutions in three-dimensional coordinates: of sheet resistance–optical transmittance–cost of produced.

In the work, sedimentation-stable sols of indium (III) and tin (IV) hydroxides were obtained by the Anion Resin Exchange Precipitation, which consists of the exchange reaction between the OH ions of the anion exchange resin and the anions of metal-containing solutions. The synthesized hydrosols were used to obtain conducting films of indium (III) In2O3 oxide and indium oxide doped with Tin In2O3: Sn, with a surface resistance of 4 kOhm/sq, thicknesses of 200–500 nm and a transparency of more than 85 %. The modes of applying precursors to glass substrates by the modified spray method and centrifugation method are selected. Films were studied using XRD, SEM, optical microscopy and spectrophotometry

The single-walled carbon nanotube-based thin films with a thickness from 11 ± 3 to 157 ± 18 nm have been formed using vacuum filtration. The thermal conductivity of the thin films as a function of thickness and temperature up to 450 K has been studied by the 3ω technique. It has been found that, in the region of 49 nm, the supplied heat from a gold strip started propagating with the high efficiency to the thin film plane. The thermal conductivity of the thin films with a thickness of 49 ± 8 nm was measured using the 3ω technique for bulk samples. It has been found that the thermal conductivity of the single-walled carbon nanotube-based thin films strongly depends on their thickness and temperature. The thermal conductivity sharply (by a factor of ~60) increases with an increase in thickness from 11 ± 3 to 65 ± 4 nm. In addition, it has been observed that the thermal conductivity of the thin film with a thickness of 157 ± 18 nm rapidly decreases from 211 ± 11 to 27.5 ± 1.4 W m–1 K–1 at 300 and 450 K, respectively.

We have synthesized ferromagnetic nanocomposite Co-Al 2 O 3 thin films via a thermite reaction between Al and Co 3 O 4 with layer geometry. The starting Al/Co 3 O 4 bilayers were obtained by the deposition of Al layers onto Co 3 O 4 films at room temperature and were annealed at temperatures between 50 and 700 °C at 50 °C intervals. Above ∼450 °C the Co 3 O 4 partially transformed into the CoO phase. The simultaneous solid-state reactions of Al with Co 3 O 4 and Al with CoO started above the initiation temperature T in ∼500 °C, which did not depend on the bilayer thickness. After annealing at 700 °C about 60% of the Co was reduced by the Al and the rest of the Co was contained in intermediate CoAl 2 O 4 shells, which separated the Co nanoparticles from the Al 2 O 3 matrix. Above 700 °C the reaction was complete and the final products were noninteracting Co nanoparticles with an average size of ∼40 nm enveloped by CoAl 2 O 4 shells, which embedded into a dielectric Al 2 O 3 matrix. The synthesized Co-Al 2 O 3 nanocomposite films possessed soft magnetic behavior and good chemical stability.

The thin-film solid-state reaction between elemental Ge and Mn across chemically inert Ag layers with thicknesses of (0, 0.3, 1 and 2.2 µm) in Ge/Ag/Mn trilayers was studied for the first time. The initial samples were annealed at temperatures between 50 and 500 °C at 50 °C intervals for 1 h. The initiation temperature of the reaction for Ge/Mn (without a Ag barrier layer) was ~ 120 °C and increased slightly up to ~ 250 °C when the Ag barrier layer thickness increased up to 2.2 µm. In spite of the Ag layer, only the ferromagnetic Mn5Ge3 compound and the Nowotny phase were observed in the initial stage of the reaction after annealing at 500 °C. The cross-sectional studies show that during Mn5Ge3 formation the Ge is the sole diffusing species. The magnetic and cross-sectional transmission electron microscopy (TEM) studies show an almost complete transfer of Ge atoms from the Ge film, via a 2.2 µm Ag barrier layer, into the Mn layer. We attribute the driving force of the long-range transfer to the long-range chemical interactions between reacting Mn and Ge atoms.

Co–ZrO 2 ferromagnetic nanocomposite thin films were successfully synthesized using a new thermite reaction between Zr and Co 3 O 4 in layer geometry. The initial Zr/Co 3 O 4 bilayers were obtained by the deposition of Zr layers onto Co 3 O 4 films at room temperature. The process of mixing at the Zr/Co 3 O 4 interface and synthesis of fine-crystalline Co and amorphous ZrO 2 phases started at a temperature above the initiation temperature T in ∼250 °С which did not depend on the bilayer thickness. For the bilayer thickness more than 300 nm high-temperature fcc-Co and cubic c-ZrO 2 (or tetragonal t-ZrO 2 ) phases were formed. For the bilayer thickness less than ∼50 nm stable low-temperature hexagonal hcp-Co and monoclinic m-ZrO 2 phases were also present in the reaction product. A partial transformation from Co 3 O 4 to CoO occurred after annealing at 300 °С. The secondary reaction between CoO and Zr started soon after Co 3 O 4 had been converted to the CoO phase. After annealing at 500 °С more than 80% of Co was reduced and the final product contained Co nanoparticles above and below the superparamagnetic critical size embedded into a dielectric ZrO 2 matrix. The synthesized Co–ZrO 2 nanocomposite films possessed soft magnetic behavior, high magnetization and good chemical stability.

Fe–ZrO 2 ferromagnetic nanocomposite thin films are successfully synthesized using a thermite reaction between the Zr and Fe 2 O 3 layers. The initial Zr/Fe 2 O 3 bilayers were obtained by the deposition of Zr layers on α-Fe 2 O 3 films at room temperature. The mixing at the Zr/Fe 2 O 3 interface and synthesis of α-Fe and the amorphous ZrO 2 phases start at a temperature above the initiation temperature T in ∼ 250 °C. Together with the formation of α-Fe, partial transformation from Fe 2 O 3 to Fe 3 O 4 occurs after annealing at 300 °C. The secondary reaction between Fe 3 O 4 and Zr starts soon after the Fe 2 O 3 is converted to the Fe 3 O 4 phase. The crystallization of amorphous ZrO 2 and the formation of the ZrO 2 cubic/tetragonal phase occurs above 400 °C. After annealing at 500 °C the reaction products contain (1 1 0) textured α-Fe nanocrystals with a diameter of about 34 nm embedded in an insulating c-ZrO 2 (or t-ZrO 2 ) matrix. The synthesized Fe–ZrO 2 nanocomposite films possess soft magnetic behavior, high magnetization and good chemical stability.

We have successfully synthesized ferromagnetic Fe–In 2 O 3 nanocomposite thin films for the first time using the thermite reaction Fe 2 O 3 + In = In 2 O 3 + Fe. The initial In/Fe 2 O 3 bilayers were obtained by the deposition of In layers on α-Fe 2 O 3 films. The reaction occurs in a self-propagating mode in a homogeneous thermal film plane field at heating rates above 20 K/s and at temperatures above initiation temperature T in ∼ 180 °С. At heating rates lower than 20 K/s the mixing of the In and Fe 2 O 3 layers occurs across the whole In/Fe 2 O 3 interface and the synthesis of the ferromagnetic α-Fe phase starts above the initiation temperature T in = 180 °С. X-ray diffraction, X-ray photoelectron spectroscopy, Mossbauer spectroscopy, transmission electron microscopy and magnetic measurements were used for phase identification and microstructure observation of the synthesized Fe–In 2 O 3 samples. The reaction products contain (1 1 0) textured α-Fe nanocrystals with a diameter around 100 nm and surrounded by an In 2 O 3 matrix. These results enable new efficient low-temperature methods for synthesizing ferromagnetic nanocomposite films containing ferromagnetic nanoclusters embedded in transparent conducting oxides.

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала. Solid-phase transformations at different annealing temperatures in Mn/Bi (Mn on Bi) and Bi/Mn (Bi on Mn) films have been studied using X-ray diffraction, electron microscopy, and magnetic measurements. It has been shown that the synthesis of the α-MnBi phase in polycrystalline Mn/Bi films begins at a temperature of ~120°C and the Mn and Bi layers react completely at 300°C. The resulting α-MnBi(001) samples have a large perpendicular magnetic anisotropy (Ku ≃ 1.5 × 107 erg/cm3) and a coercive force H > HC ~ 3 kOe. In contrast to Mn/Bi, the ferromagnetic α-MnBi phase in Bi/Mn films is not formed even at annealing processes up to 400°C and Mn clusters are formed in a Bi melt. This asymmetry in phase transformations occurs because chemosorbed oxygen existing on the surface of the Mn film in Bi/Mn films suppresses a solid-phase reaction between Mn and Bi. The analysis of the results obtained implies the existence of new low-temperature (~120°C) structural transformation in the Mn–Bi system. Твердофазные превращения в зависимости от температуры отжига в Mn/Bi (Mn на Bi) и Bi/Mn ( Bi на Mn) пленках исследовались с использованием рентгеновской дифракции, электронной микроскопии и магнитных измерений. Показано, что синтез альфа-MnBi фазы в поликристаллических Mn/Bi пленках начинается при при температуре 120 К и при 300 К слои Mn и Bi реагируют полностью. Полученные образцы альфа-MnBi(001) обладали большой перпендикулярной анизотропией и большой коэрцитивной силой H>Hc =3 kЭ. В отличие от Mn/Bi в пленках Bi/Mn даже при отжигах до 400 С ферромагнитная альфа-MnBi фаза не образовывалась, а наблюдалось образование кластеров Mn в расплаве Bi. Данная асиметрия в фазовых превращениях объясняется существованием в пленке Bi/Mn на поверхности Mn хемосорбционного кислорода, который подавляет твердофазную реакцию между Mn и Bi. На основании анализа результатов проведенныъх исследований предполагается существование низкотемпературного (120 С) структурного превращения в Mn-Bi-системе.

The negative magnetoresistance of thin In 2 O 3 films, obtained by an autowave oxidation reaction, was detected within a temperature range of 4.2–80 K. The magnetoresistance was –1.35% at a temperature of 4.2 K and an external magnetic field of 1 T. A weak localization theory was used to explain the negative magnetoresistance and to determine the phase-coherence length in a temperature range of 4.2–80 K. The phase-coherence length was found to oscillate as the temperatures increased to around 30 K. From the maximum and minimum values of the oscillation of the phase-coherence length, it was suggested that the In 2 O 3 film has two structure characteristic parameters. Transmission electron microscopy showed the structure of the thin In 2 O 3 film to have structural features of a «crystal phase – amorphous phase». It was found that the crystalline phase characteristic size was consistent with the maximum phase-coherence length and the amorphous phase characteristic size was consistent with the minimum phase-coherence length. It has been suggested that the temperature measurements of the magnetoresistance and the theory of weak localization can be used to evaluate the structural features of nanocomposite or nanostructured thin films.