Search

Sm17(Co1−xCux)83 and Er17(Co1−xCux)83 (at. %, x = 0–1) alloy thin films are prepared on Cr(100) single-crystal underlayers at 500 °C by molecular beam epitaxy. The effect of Cu/Co composition on the ordered phase formation is investigated. Sm17(Co1−xCux)83(11 2 ¯ 0) films with hexagonal Sm(Co,Cu)5 (D2d) ordered phase grow epitaxially on the underlayers for all the compositional range of x = 0–1. On the contrary, the structure of Er17(Co1−xCux)83 film varies depending on Cu composition. Amorphous phase is formed in the Er17Co83 (x = 0) film. Er17(Co1−xCux)83(11 2 ¯ 0) epitaxial films with Er(Co,Cu)5 (D2d) ordered phase are obtained for the compositional range of x = 0.25–0.5. With further increasing the x value, the crystallographic phase varies to a phase other than D2d. Partial substitution of the Co sites in ErCo5 structure with Cu atoms and control of the amount of Cu atom are important to stabilize the Er(Co,Cu)5 phase.

Fe thin films are prepared on MgO substrates of (001), (110), and (111) orientations by ultra-high vacuum magnetron sputtering. The magnetostriction behaviors under rotating magnetic fields are observed by using a cantilever method. The relationship between in-plane magnetic anisotropy and magnetostriction behavior is investigated. An Fe(001)bcc single-crystal film is obtained on MgO(001) substrate. A four-fold symmetry in in-plane magnetic anisotropy is observed for the Fe(001)bcc film, where the easy magnetization directions are parallel to bcc[100] and bcc[010]. An Fe(211)bcc bi-crystalline film is formed on MgO(110) substrate and the film also shows an almost four-fold symmetric magnetic anisotropy. The reason is interpreted to be due to an influence of overlap of magnetic anisotropies of two bcc(211) variants with two effective easy magnetization directions which are obtained by projecting bcc[010] and bcc[001] on the bcc(211) plane. An Fe(110)bcc film is epitaxially grown on MgO(111) substrate with two types of variant with the crystallographic orientation relationships similar to Nishiyama-Wasserman and Kurdjumov-Sachs. The Fe(110) film shows an isotropic in-plane magnetic property due to an influence of the variant structure. Usual sinusoidal waveforms of magnetostriction are observed for the Fe(110) film. On the other hand, waveforms measured for the Fe(001) and the Fe(211) films are deformed from sinusoidal shape under low in-plane rotating magnetic fields and the magnetostriction behaviors are similar between the two films. Rectangular waveforms are observed for the bending parallel to easy magnetization directions, whereas triangular waveforms are recognized for the bending parallel to hard directions. The phenomenon is related to the direction difference between applied magnetic field and magnetization in magnetically unsaturated films with in-plane anisotropies. The magnetostriction behavior is influenced by the symmetry of in-plane magnetic anisotropy.

Fumigation has been the most convenient method in the field of pest control in museums. In this study, as fumigants, ethanol 70%, deltamethrin (commercial pesticide (CP) ) , essential oil (EO) from Pinus regida, and low oxygen microenvironment (0.1%, (LOM) ) were tested individually and jointly against museum fungal strain Alternaria alternata. Three concentrations of each CP and EO were chosen for evaluating the individual effect. In the joint action fumigation process, three lower concentrations of CP and EO were tested in LOM. The rate of mycelial growth inhibition at each fumigation process was determined by two steps: 1) directly after the fumigation process and 2) after 7 d of the inoculation of the fumigated spores in new medium and incubating it in normal condition. The results demonstrated that applying of each chemical (CP or EO) in LOM enhanced its fungicidal activity and that effect of EO improved from fungistatic to fungicidal by jointing with LOM.

Er17(Co1− x Cu x )83 (at. %, $x = 0-1$ ) alloy thin films are prepared at 500 °C by employing Cr(211) underlayers hetero-epitaxially grown on MgO(110) substrates. Crystallographic phase formation is influenced by the Cu/Co composition. Amorphous film is formed for $x = 0$ , whereas epitaxial films are obtained for $x = 0.25-1$ . Cu atom addition into Er–Co film promotes crystallization. The films with $x = 0.25-0.5$ consist of a mixture of Er(Co,Cu)5 $(1\bar {1}00)$ and Er(Co,Cu)5(0001) crystals. The crystallographic orientation relationships are Er(Co,Cu)5 $(1\bar {1}00)[\bar {1}\bar {1}20]~\vert \vert $ Cr(211) $[\bar {1}11], (211)[1\bar {1}\bar {1}]$ and Er(Co,Cu)5 $(0001)[\bar {1}\bar {1}20]~\vert \vert ~\text {Cr}(211)[\bar {1}11], (211)[1\bar {1}\bar {1}]$ . However, with further increasing $x$ value, the crystallographic phase changes to a phase different from Er(Co,Cu)5. Control of the amount of Cu atom is important to stabilize the Er(Co,Cu)5 phase.

FePt alloy films of 2 to 10 nm thicknesses are prepared on (001) single-crystal underlayers of MgO, VN, and VC by employing a two-step method consisting of low-temperature deposition at 200 °C followed by high-temperature annealing at 600 °C. MgO, VN, and VC crystals are selected as underlayer materials, since the crystals have the same NaCl-type crystal structure and similar lattice constants of about 0.42 nm but different surface energies. The single-crystal underlayers are prepared by RF sputtering on the single-crystal substrates of MgO and SrTiO3 at 600 °C. The influences of underlayer material and FePt film thickness on the $L1_{0}$ ordering degree, the magnetic properties, and the surface morphology are systematically investigated. Epitaxial films involving $L1_{0}$ (001) crystal structure with the $c$ -axis normal to the substrate surface are formed on all the underlayers. As the film thickness decreases, the ratio of out-of-plane to in-plane lattice constant $c/a$ decreases and the ordering degree $S$ increases. Stronger perpendicular magnetic anisotropy is observed for an FePt film with a higher $S$ value. The film thickness trends of $c/a$ , $S$ , and magnetic properties are similar to those for FePt films thicker than 5 nm formed on MgO underlayers. However, when the thickness is decreased to 2 nm, de-wetting of deposited atoms occurs on MgO underlayers during annealing at 600 °C. The surfaces of 2-nm-thick films formed on MgO underlayers are composed of isolated islands. On the contrary, continuous surfaces are realized for the investigated film thickness range of 2–10 nm in the cases of VC and VN underlayers. The surface roughness of FePt film formed on VN underlayer ( $R_{a}$ : 0.1–0.2 nm) is lower than that of film formed on VC underlayer ( $R_{a}$ : 0.1–0.4 nm). This paper shows that the employment of a VN underlayer is effective in the preparation of $L1_{0}$ ordered FePt ultra-thin film with flat surface.

Sm17Co83 (at%) films are prepared on bcc-Cr(211), bcc-Fe(211), bcc-Fe65Co35(211), and hcp-Co(1 1 ( _ ) 00) underlayers hetero-epitaxially grown on MgO(110) substrates at 500 °C by using a UHV-MBE system. The growth behavior and the structures are investigated by in-situ reflection high-energy electron diffraction and X-ray diffraction. Sm-Co(1 1 ( _ ) 00) single-crystal films of RT5 ordered structure with the c-axis lying in the film plane grow epitaxially on the underlayers. Small volumes of amorphous phases are interpreted to be involved in the films deposited on these underlayers. The crystal lattice of RT5 magnetic film is slightly deformed from the bulk hexagonal structure, which is caused possibly by the lattice mismatch with the underlayer. The order degree of film deposited on Cr underlayer is higher (S=0.77) than those prepared on Fe, Fe65Co35, and Co underlayers (S: 0.67–0.71). The films show in-plane uniaxial magnetic anisotropies reflecting the magnetocrystalline anisotropy of SmCo5 crystal.

Fumigation has been the most convenient method in the field of pest control in museums. In this study, as fumigants, ethanol 70%, deltamethrin (commercial pesticide (CP) ) , essential oil (EO) from Pinus regida, and low oxygen microenvironment (0.1%, (LOM) ) were tested individually and jointly against museum fungal strain Alternaria alternata. Three concentrations of each CP and EO were chosen for evaluating the individual effect. In the joint action fumigation process, three lower concentrations of CP and EO were tested in LOM. The rate of mycelial growth inhibition at each fumigation process was determined by two steps: 1) directly after the fumigation process and 2) after 7 d of the inoculation of the fumigated spores in new medium and incubating it in normal condition. The results demonstrated that applying of each chemical (CP or EO) in LOM enhanced its fungicidal activity and that effect of EO improved from fungistatic to fungicidal by jointing with LOM.

In storage of modern museums, collections are packed and stored with acid-free paper-based materials for keeping safe and stable conditions. Direct contact of fungal contaminated packing and storing materials with the collections is concerned about expanding of infection in storage facilities. In this study, fungicidal effects of UV light irradiation on the materials such as archival board and Japanese tissue paper contaminated with Penicilliun commune and Chaetomium globosum were tested. The analyzed materials were divided into two groups; Group 1 was examined with 20 μl of spore suspensions of fungi (106 cfu/ml) ; and Group 2 was tested on Czapek- Dox agar medium modified without sugar and inoculated with 100 μl of the spore suspensions of fungi (106 cfu/ml) . Six doses of UV irradiation were examined on Group 1 and five doses on Group 2 in addition to control. The assessment was done by using 1) adenosine triphosphate (ATP) bioluminescence assay and double staining to determine the cell viability; 2) observation under light microscope to evaluate morphophysiological change of tested fungi (spores and hyphae) . Because of the thinness and high transparency of tissue paper, UV irradiations were highly efficient to fungicide its fungal contamination compared with archival board. In spite of the high resistance of C. globosum spores, the rate of growth was slow, and with a little amount of perithecia or fruiting bodies and a high amount of ycelium (which damaged rapidly through UV irradiation) . This may be due to a low relative humidity of the incubation environment. Minimum dosage of UV irradiation with fungicidal effectiveness against all fungal contamination was estimated as 118 J/cm2.

Fe50PtxPd50−x (at%, x=0–50) alloy films of 10 nm thickness with and without 2-nm-thick MgO cap-layers are prepared on MgO(001) single-crystal substrates by employing a two-step method consisting of low-temperature deposition at 200 °C followed by high-temperature annealing at 600 °C. The influences of MgO cap-layer on the structure and the magnetic properties are investigated. Fe50PtxPd50−x films epitaxially grow on the substrates at 200 °C. The Fe50Pd50 and the Fe50Pt12.5Pd37.5 films are respectively composed of (001) single-crystals with disordered fcc-based (A1) and bcc-based (A2) structures. The films with x > 25 consist of mixtures of A1 and A2 crystals. The volume ratio of A2 to A1 crystal decreases with increasing the x value from 25 to 50. The in-plane and out-of-plane lattices are respectively expanded and shrunk due to accommodation of lattice mismatch between film and substrate. When the films are annealed at 600 °C, phase transformation to L10 ordered phase takes place. L10 phase transformation of Fe50PtxPd50−x film is promoted for a sample with MgO cap-layer and the order degree is higher than that without cap-layer. Furthermore, L10 ordering with the c-axis perpendicular to the substrate surface is enhanced for the film with cap-layer. The cap-layer is considered to be giving a tension stress to the magnetic film in lateral direction which promotes L10 ordering with the c-axis perpendicular to the substrate. Deposition of cap-layer is shown effective in achieving higher order degree and in enhancing perpendicular magnetic anisotropy with Fe(Pt,Pd) films.

Sm 17 Co 83 /Fe 65 Co 35 (at. %) multilayer films are prepared on MgO(110) substrates at 500 °C by ultra-high vacuum molecular beam epitaxy. The film crystallographic properties during formation are investigated by in-situ reflection high-energy electron diffraction. The 1st Fe–Co layer epitaxially grows on the substrate with two variants whose orientations are rotated around the film normal by 180° each other. The 1st Sm–Co layer formed on the 1st Fe–Co layer involves a small volume of amorphous phase in addition to epitaxial (11¯00)) crystal of RT 5 structure with the c -axis lying in the film plane. The crystallographic quality of 2nd Fe–Co layer is inferior to that of 1st Fe–Co layer. The 2nd Sm–Co layer is composed of polycrystal and amorphous phases. The crystallographic properties of Sm–Co and Fe–Co layers are delicately influenced by those of lower layers. The Sm–Co/Fe–Co multilayer films involving Sm–Co(11¯00) RT 5 epitaxial crystal show in-plane uniaxial magnetic anisotropies reflecting the magnetocrystalline anisotropy of SmCo 5 crystal. The coercivity increases with increasing the volume of Sm–Co(11¯00) RT 5 crystal.

Magnetic force microscope (MFM) tips are prepared by coating silicon tips of 4 nm radius with 20-nm-thick metallic magnetic films with and without 2-nm-thick oxidation protection layers. Iron (Fe) is used as the magnetic material, whereas carbon (C), silicon nitride (Si-N), or silicon carbide (Si-C) is employed as the protection layer. The MFM tips are exposed in an environment of high temperature of 70 °C and high relative humidity of nearly 100%. The effect of protection layer on the spatial resolution is investigated as a function of period of exposure to the environment. The resolution of MFM tip without protection layer deteriorates from 7.2 to 21.2 nm in 10 days. The deterioration is attributed to an increase in the tip radius and a loss of the detection sensitivity caused by oxidation of coated Fe material. In contrast, the resolutions of tips with C, Si-N, and Si-C layers are kept almost constant at 12.1 ± 0.5, 12.1 ± 0.5, and 14.8 ± 2.1 nm for a time span of 10 days, respectively. The coating of a very thin protection layer has been shown effective in keeping the MFM tip performance for a long period of time by preventing the oxidation of coated metallic magnetic material.

Resinous materials are considered the most important embalming agent, which help in the preservation of ancient Egyptians bodies over time. They differ in type and amount from one mummy to another based on the period, embalmer and the social position of the deceased. With the aim of evaluating the role of resinous materials in the preservation of the wrapping textiles of mummies in the present study, three wrapping textile fragments (Anc. 1, Anc. 2 and Anc. 3) were collected from three mummies dating back to the ancient Egyptian Late Period (525-343 BC). These fragments differ in their amounts of adherent resin. The three fragments were soaked in a mixture of dichloromethane and methanol (DCM: MeOH, 1:1 v/v) in order to extract resinous materials from the fibers of the linen textiles. Fourier Transform Infrared Spectroscopy (FTIR) analysis of the extracts proved that the Anc. 2 and Anc. 3 samples included resinous materials; while, the Anc. 1 sample did not contain any adherent resinous materials. Linen fibers from the three tested fragments were investigated by stereomicroscope, microbiological investigation, scanning electron microscope (SEM) and FTIR. The results showed that resinous materials have an important role in protecting the linen wrappings from microbial damage. They also preserved the fibers’ morphological structure from deterioration caused by weathering. The FTIR results proved increasing oxidation of the Anc. 1 sample and the decreasing of its crystallinity index more than the other samples as a result of its direct contact with environmental deterioration factors.

Fe50(Pt1–xPdx)50 (at. %, x = 0, 0.25, 0.5, 0.75, 1) alloy thin films are prepared on MgO(001) substrates by using two methods, high-temperature deposition at 600 °C (one-step method) and low-temperature deposition at 200 °C followed by annealing at 600 °C (two-step method). The influence of formation method on the film structure is investigated. L10 crystals epitaxially grow on the substrates when films are deposited at 600 °C. Disordered crystals transform into L10 structure when films are annealed at 600 °C. The films with x > 0.5 consist of L10(001) crystals with the c-axis normal to the substrate surface, whereas the films with x < 0.25 involve small volumes of L10(100) crystals with the c-axis lying in the film plane. Similar final crystallographic orientation is realized for the Fe (Pt,Pd) films prepared by employing the two different methods. The films prepared by one-step method possess island-like surfaces involving side facets, while those prepared by two-step method have very flat surfaces with the arithmetical mean roughness lower than 0.2 nm. The two-step method is effective for preparation of Fe (Pt,Pd) films with flat surfaces.

Ni100− x Fe x ( $x = 0$ , 20 at.%) and Ni100− y Co y ( $y = 0$ , 25, 50, 75, and 100 at.%) alloy single-crystal films of fcc(001) orientation are prepared through heteroepitaxial growth on Cu(001) single-crystal underlayers at 300 °C. The effects of Fe/Ni and Co/Ni compositions on the magnetic anisotropy and the magnetostriction behavior under rotating magnetic fields are investigated. The Ni single-crystal film shows a nearly isotropic in-plane magnetic property. The Ni80Fe20 and Ni100− y Co y ( $y = 25$ –100) single-crystal films show fourfold symmetries in in-plane magnetic anisotropy. The easy magnetization direction is observed along [110] and [ $1\bar {1}0$ ] for the Ni80Fe20 and the Ni100− y Co y ( $y = 50$ –100) films, whereas that is recognized along [100] and [010] for the Ni75Co25 film. The easy magnetization axis varies depending on the Co/Ni composition. The in-plane magnetic anisotropy increases with increasing the Co content. Triangular output waveforms of magnetostriction appear when the Ni80Fe20 and Ni100− y Co y ( $y = 25$ –100) films are measured under low rotating magnetic fields. The magnetostriction behavior is related to the magnetization direction in a magnetically unsaturated film with in-plane magnetic anisotropy. As the rotating magnetic field increases, the magnetization approaches saturation and the waveform gradually changes to a usual sinusoidal shape. As the in-plane anisotropy increases, a higher rotating field is required to obtain a sinusoidal waveform. On the contrary, sinusoidal waveforms are observed for the Ni film, even when the magnetization is not saturated. The waveform of magnetostriction is affected by the symmetry and the strength of in-plane magnetic anisotropy.

L1 0 films formed on (001)-oriented underlayers or substrates may involve (100) crystal with the c-axis lying in the film plane in addition to (001) crystal with the c-axis normal to the film surface. In this paper, FePt, CoPt, and FePd alloy films with L1 0 structure are prepared on MgO(001) single-crystal substrates. The c-axis orientation is accurately controlled to be perpendicular by introducing a thin MgO cap layer on magnetic films with disordered structure prepared by low-temperature deposition at 200 °C and by annealing the bilayer films at 600 °C. The phase transformation preferentially occurs along the perpendicular direction in the MgO/(FePt, CoPt, FePd)/MgO sandwich structures. Furthermore, the cap layer promotes L1 0 ordering. The order degrees of FePt, CoPt, and FePd films with and without cap layers, (S w/ , S w/o ), are (0.82, 0.58), (0.36, 0.30), and (0.72, 0.62), respectively. The FePt film with cap layer shows a strong perpendicular magnetic anisotropy and a very low in-plane coercivity because of which the film does not include L1 0 (100) crystal and possesses a high-order degree.

Co x Pt 100-x (at. %) alloy epitaxial films with the close-packed plane parallel to the substrate surface are prepared on MgO(111) substrates heated at 300 °C by varying the Co content of x from 0 to 100. The stacking sequence of close-packed plane (the volume ratios of fcc and hcp crystals, V fcc and V hcp ) and the order degree are quantitatively determined. The films with Pt-rich and nearly equiatomic compositions primarily consist of fcc crystals (V fcc >0.9). With increasing the x value beyond 56, the V hcp value drastically increases. The films with Co-rich compositions consist of mixtures of hcp (V hcp ≈0.8) and fcc (V fcc ≈ 0.2) crystals. The films with 31 ≤x≤ 86 involve metastable ordered phases. The order degree of S L11 ,Bh is kept constant around 0.25 in a compositional range of 31 × 75. From the viewpoints of volume ratios of fcc and hcp crystals and order degree, the crystal structure is determined to vary A1 A1 + SFs (SFs: stacking faults) L1 1 + SFs ⇒L1 1 + Bh (+D0 19 ) ⇒A3 + SFs with increasing the x value. The films including ordered phases show strong perpendicular magnetic anisotropies. It is shown that the uniaxial magnetocrystalline anisotropy energy of Co x Pt 100-x film can be kept >10 7 erg/cm 3 while controlling the saturation magnetization from 600 to 1150 emu/cm 3 .

FePd, FePt, and CoPt alloy thin films are deposited on (001) single-crystal substrates of MgO, SrTiO3, and LaAlO3 at 600°C by using an ultra-high vacuum radio-frequency magnetron sputtering system. The c-axis distribution and the order degree are carefully studied. The FePd films deposited on MgO and SrTiO3 substrates consist of L10(001) crystals with the c-axis perpendicular to the film surface. The FePd film deposited on LaAlO3 substrate and the FePt and the CoPt films deposited on all the substrates include L10(100) crystals with the c-axis lying in the film plane. The c-axis distribution is influenced by the combination of film and substrate materials. Higher order degrees are observed for the film material CoPt

Sm17Ni83 (at.%) alloy thin films are prepared on Cu underlayers hetero-epitaxially grown on MgO(111) single-crystal substrates by employing an ultra-high vacuum molecular beam epitaxy system. The substrate temperature is varied from 100 °C to 500 °C. The film growth behavior and the detailed resulting film structure are respectively investigated by in situ reflection high-energy electron diffraction and by a combination of out-of-plane and in-plane X-ray diffractions. With increasing the temperature up to 300 °C, formation of ordered SmNi5 phase is recognized. The films deposited above 400 °C consist of only epitaxial SmNi5 (0001) crystal, whereas the films deposited below the temperature include amorphous phase and/or a hexagonal ordered phase other than SmNi5. When the temperature is increased from 300 °C to 500 °C, the long-range order degree of SmNi5 film increases from 0.60 to 0.97. SmNi5 phase formation is enhanced with increasing the temperature.

FePd, FePt, and CoPt alloy thin films are prepared on MgO(110) single-crystal substrates by using two different methods. One is one-step method consisting of deposition at an elevated substrate temperature of 600°C and the other is two-step method consisting of low-temperature deposition at 200°C followed by annealing at 600°C. The crystal structure, the crystallographic orientation, and the surface morphology are compared. L10 ordered FePd, FePt, and CoPt films epitaxially grow on the substrates with three variants, (110), (101), and (011), when deposited at 600°C. The c-axis of L10(110) variant is lying in the film plane, whereas those of L10(101) and L10(011) variants are 45° canted from the substrate surface. Disordered FePd, FePt, and CoPt single-crystal films of (110) orientation are formed by deposition at 200°C. An A1-L10 phase transformation occurs along A1[001], A1[010], and A1[001] by annealing the disordered films at 600°C. The annealed films thus consist of three L10 variants. Similar final crystal structure and orientation are realized in the FePd, the FePt, and the CoPt films prepared by employing the two different methods. The L10 ordered films prepared by one-step method have island-like surfaces involving facets, whereas those prepared by two-step method have very flat surfaces with the arithmetical mean roughness lower than 0.3 nm. The two-step method is useful for preparation of L10 ordered films with flat surfaces.