Evidence of competition in the incorporation of Co²⁺ and Mn²⁺ ions into the structure of ZnTe nanocrystals

Abstract

Glass-embedded Zn_1−x−yMn_xCo_yTe nanocrystals (with x = 0.01 and y varying from 0.000 to 0.800) were successfully synthesized using a protocol based on the melting–nucleation synthesis route and herein investigated by several experimental techniques. Optical absorption (OA) provides evidence of the incorporation of substitutional Co²⁺ ions in the semiconducting Zn_1−x−yMn_xCo_yTe lattice and shows that with increasing Co concentration these ions may also be dispersed into the glass matrix, causing structural disorder. Atomic force microscopy (AFM) images reveal the size of the nanocrystals and magnetic force microscopy (MFM) gives evidence of the paramagnetic behavior of the doped samples. X-ray diffraction (XRD) and Raman scattering reveal that high Co concentrations increase the structural disorder in the host glass matrix. Electron paramagnetic resonance (EPR) spectroscopy reveals the presence of Mn²⁺ ions inside and at (or near) the surface of the ZnTe nanocrystals, and also that the increase of Co doping concentration reduces the incorporation of Mn²⁺ ions into the ZnTe structure, simultaneously increasing their dispersion into the glass matrix.

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1. Introduction

The most extensively studied semimagnetic semiconductors, also known as diluted magnetic semiconductors (DMS),^1–3 are alloys based on II–VI semiconductor compounds in which a fraction of cations has been randomly replaced by transition metals, typically Mn, Fe and Co.⁴ The main characteristic of these DMS is the possibility of an exchange interaction between electrons of the sp energy sublevel of the host semiconductor and the partially filled d sublevel, of the magnetic atom, introduced intentionally into the structure. Incorporating transition metal ions into DMS creates intermediate energy states between the valence and conduction bands of the host semiconductor and allows manipulation of the magnetic properties, promoting novel applications of the doped DMS structure, such as in the area of spintronics.^5–7

When a semiconductor is doped with two or more transition metal ions, simultaneous exchange interactions between electrons of the sp sublevel of the host semiconductor and the d sublevel of each transition metal ion (Mn²⁺ and Co²⁺, for instance), can occur. This doping can give rise to a competition in the substitutional incorporation of the transition metal cations into the crystalline lattice of the host semiconductor. This competitive incorporation, introducing additional carriers,^8,9 into the nanocrystals (NCs), can alter their structural, optical, vibrational, and magnetic properties. In this context, this work reports probably for the first time the effects of the concentration of Co-doping, varying from 0.00 to 0.80, on the physical properties of Zn_1−x−yMn_xCo_yTe NCs, with nominal Mn-doping x = 0.01, grown by the fusion method in the P₂O₅–ZnO–Al₂O₃–BaO–PbO glass system (referred to as PZABP matrix).

2. Experimental

Mn²⁺- and Co²⁺-doped ZnTe NCs (Zn_1−x−yMn_xCo_yTe samples) were grown by fusion in a glass matrix with a nominal composition of 65P₂O₅·14ZnO·1Al₂O₃·10BaO·10PbO (mol%) adding 2Te (wt%), Mn at doping x = 1 (wt%) (or x = 0.010) content, and Co at doping y content varying from 0 to 80 (wt%) with Zn content. Even though the effective Mn and Co concentrations in our nanoparticle samples have not been evaluated, they are expected to be slightly lower than the nominal concentrations (x = 0.010 and y varying from 0.000 to 0.800), since the final amounts of Mn²⁺ and Co²⁺ ions present in the glass matrix are proportional to their nominal concentrations. Thus, the highest (lowest) nominal concentration is related to the greatest (smallest) final amount of Mn²⁺ and Co²⁺ in the glass template. After the fusion process in alumina crucibles at 1300 °C for 30 minutes and fast cooling to room temperature, the PZABP glass samples were thermally annealed at 500 °C for 10 hours to enhance the diffusion of Zn²⁺, Mn²⁺, Co²⁺, and Te²⁻ ions throughout the host matrix and induce the growth of Zn_1−x−yMn_xCo_yTe NCs. Further details on the growth of NCs in glass synthesized by glass-melting nucleation are given in the ref. 10–15.

The properties of as-grown Zn_1−x−yMn_xCo_yTe NCs were investigated by optical absorption (OA), atomic/magnetic force microscopy (AFM/MFM), X-ray diffraction (XRD), Raman spectroscopy and electron paramagnetic resonance (EPR) spectroscopy. Room temperature OA spectra show optical transition peaks in the UV-VIS-NIR range from 250 to 2500 nm. These peaks were recorded with a model UV-3600 Shimadzu UV-VIS-NIR spectrometer operating in the range from 190 to 3300 nm, with a resolution of 1 nm. A Shimadzu Scanning Probe Microscope (SPM-9600) was used to obtain AFM/MFM images in which the resolution in the vertical z-direction for topographic images was 0.01 nm. The tapping-mode was used to study the sample surface topography (AFM) and the lift-mode, to study the magnetic phase (MFM). In the lift-mode, the tip–sample distance varied from tens to hundreds of nanometers. High-quality MFM images exhibiting a regular distribution of NCs on the flat surface of the host glass matrix were obtained, after a meticulous polishing procedure to ensure that irregularities in the glass surface were smaller than the average size of the nanostructures. XRD patterns were recorded using a XRD-6000 Shimadzu diffractometer equipped with monochromatic Cu-K_α1 radiation (λ = 1.54056 Å) and set to a resolution of 0.02°. Raman spectra were obtained with a JY-T64000 micro-Raman spectrometer exciting the samples with the 514.5 nm line of an argon laser. The EPR spectra were obtained at Q-band (∼34 GHz) microwave frequency using a Bruker Elexis spectrometer with swept static magnetic field and the usual modulation and phase sensitive detection techniques. All measurements were performed at a room temperature of 300 K.

3. Result and discussion

Fig. 1 shows the OA spectra in the range from 250 to 750 nm [Fig. 1(A)], and from 750 to 2500 nm [Fig. 1(B)], for pure PZABP glass matrix sample and samples containing Zn_1−x−yMn_xCo_yTe NCs doped with Mn nominal concentration x = 0.010 and Co nominal y-concentrations varying from 0.000 to 0.800. For comparison, the inset in Fig. 1(A) shows the OA spectra of the glass sample containing Zn_1−x−yMn_xCo_yTe NCs (with x = 0.01 and y = 0.050) and the sample doped only with Co (PZABP:0.05Co sample). The inset in Fig. 1(B) shows the spin transitions of Co²⁺ (3d⁷) detailed energy levels in tetrahedral symmetry. The photographs to the right of Fig. 1(B) show the glass samples where the PZABP matrix is transparent and the samples doped with Zn_1−x−yMn_xCo_yTe gradually change color with increasing concentration. The OA spectra demonstrate that the glass matrix is transparent in the near UV range, the spectral range where the ZnTe and Zn_1−x−yMn_xCo_yTe NCs exhibit optical absorption. Accordingly, the glass matrix is essential to verify the successful growth of both ZnTe and Zn_1−x−yMn_xCo_yTe NCs via the OA spectra. For x = 0.010 and y = 0.000, a good fitting of the OA spectrum is obtained by considering three electronic transitions, represented in this figure by three dashed Gaussian peaks. As it has been reported,^10,12,13,15 the absorption bands centered at approximately 3.10 eV (400 nm) and 2.33 eV (535 nm) are attributed, respectively, to Zn_1−xMn_xTe nanocrystals in quantum confinement regime (QDs) and with bulk-like properties (i.e. without quantum confinement). The third peak, at lower wavelength (lower than 280 nm (E_g = 4.43 eV)) is related to the glass optical gap.

Fig. 1 OA spectra of the PZABP template and of Zn_1−x−yMn_xCo_yTe NC samples embedded in this template at Mn-doping content x = 0.010 and different Co-doping contents: y varying from 0.000 to 0.800, in the range of 250 to 750 nm (A) and in the range of 750 to 2500 nm (B). Photographs of the glass samples are shown to the right of (B).

In addition to the bands attributed to Zn_1−xMn_xTe QDs and bulk NCs properties, Fig. 1 also presents four characteristic bands in the 500–700 nm region and three characteristic bands in the 1200–2000 nm region, for all doped samples with Mn (x = 0.010) and Co (y ≠ 0.000), whose intensity of these additional bands is enhanced with the increasing cobalt y-content. The four bands in the visible region of the electromagnetic spectrum (Fig. 1(A)) were also observed in Zn_1−xCo_xO NCs synthesized by the sol–gel method,¹⁶ and in thin films of Zn_1−xCo_xS grown by pulsed laser deposition (PLD).¹⁷ They are due to the spin-allowed transition: ⁴A₂(F) → ⁴T₁(P) (582 nm); and spin-forbidden transitions: ⁴A₂(F) → ⁴A₁(G) (538 nm), ⁴A₂(F) → ⁴T₁(G) (620 nm) and ⁴A₂(F) → ²E(G) (650 nm), in the Co²⁺-ion ligand-field region.¹⁷ These absorption edges are correlated with the d–d transitions of the tetrahedrally coordinated Co²⁺-ions.¹⁷ All samples containing Zn_1−x−yMn_xCo_yTe NCs (with x = 0.010 and y ≠ 0.000) exhibit extremely intense absorption in the visible and near-infrared (NIR) region that increases at higher concentrations of Co²⁺ and that is due to greater numbers of Co²⁺ ions located in the tetrahedral sites of Zn_1−xMn_xTe:Co²⁺ NCs.

The NIR broad absorption band centered at 1538 nm (0.81 eV) is attributed to the spin and electric-dipole allowed A₂(⁴F) → ⁴T₁(⁴F) transition. This spin-allowed transition can be explained by the spin–orbit coupling interaction that splits the ⁴T₁(⁴F) excited state into three sub-states: Γ₆, Γ₈ and Γ₈ + Γ₇. Fig. 1(B) shows the optical absorption energy involved in these splitting states: E₂₁, E₂₂ and E₂₃.^18–20 This result is in agreement with results observed in other materials^18,19 and indicates the substitution of Co²⁺-ions at tetrahedral Zn²⁺-ion sites in positions that are characteristic of this site.¹⁷

It must be inferred that, at high Co concentrations, dispersion of Co²⁺ ions throughout the PZABP glass matrix may occur, causing some structural distortions. This would explain the electronic transitions related to the absorption of Co²⁺ ions visible in the OA spectrum of the PZABP:0.05Co sample, but with lower intensity than in the vitreous samples containing Zn_1−x−yMn_xCo_yTe NCs (x = 0.01 and y = 0.050). This difference in sample OA spectra intensity (with the same Co concentration) results from strong exchange interactions between the electrons in the 3d sublevel of Mn²⁺ and Co²⁺ ions and electrons in the sp sublevel of the host semiconductor (ZnTe); this does not occur in the glass doped only with Co (PZABP:0.05Co). Thus, it can be concluded that at high Co concentrations, Co²⁺ ions are both incorporated into Zn_1−xMn_xTe NCs (forming Zn_1−x−yMn_xCo_yTe NCs) at sites with tetrahedral coordination, and dispersed throughout the PZABP glass matrix, probably at some highly distorted sites.

Fig. 2 shows AFM/MFM images from the sample of PZABP matrix containing non-doped ZnTe NCs (x = 0.000 and y = 0.000) [Fig. 2(A)], and from samples of Zn_1−x−yMn_xCo_yTe (with x = 0.010 and y = 0.000) [Fig. 2(B)], Zn_1−x−yMn_xCo_yTe (with x = 0.010 and y = 0.050) [Fig. 2(C)] and Zn_1−x−yMn_xCo_yTe (with x = 0.010 and y = 0.800) [Fig. 2(D)].

Fig. 2 (A)–(D) Room temperature AFM/MFM images of ZnTe and Zn_1−x−yMn_xCo_yTe NCs with x-content equal to 0.010 and different y-content (as indicated). Left side of each panel: topographic image (AFM) with the height distribution (top of each panel) for NCs (QDs and bulk). Right side of each panel: corresponding phase image (MFM) where the contrast between the north (N) and south (S) magnetic poles identifies the orientation of the total magnetic moment of the DMS NCs.

Each panel in Fig. 2 shows a topographic image (2D), a corresponding magnetic phase image (right panel), and size distribution of QDs and bulk NCs, at the top. From the AFM images (topographical), the mean radius of QDs is R ≈ 2.14 nm, as shown in Fig. 2(A)–(D) by the values: (i) R ≈ 2.11 nm, for ZnTe; (ii) R ≈ 2.15 nm, for x = 0.010 and y = 0.000; (iii) R ≈ 2.12 nm, for x = 0.010 and y = 0.050, and (iv) R ≈ 2.16 nm, for x = 0.010 and y = 0.800. These values agree with those deduced from the OA spectra in ref. 10. The average R estimated from the AFM images of NCs with bulk properties was approximately R ≈ 8.14 nm; above R ≈ 5.39 nm, ZnTe NCs began to exhibit bulk properties.⁷ As in our previous works,^11,13–15 the NC size remained unchanged as the Mn concentration increased. This is expected, given that all samples were synthesized under the same thermodynamic conditions.

The great contrast revealed in the MFM images (magnetic phase) of Fig. 2(B)–(D) is a clear indication of the magnetic property of Zn_1−x−yMn_xCo_yTe NCs. At these dimensions, these contrasts occurs because of force gradients present in the region between the MFM tip and the magnetization of the sample's surface, that is, the samples containing magnetic ions (Mn²⁺ and Co²⁺) respond magnetically when induced by the tip magnetization. According to the literature, the dark (light) contrasts shown in the MFM images [Fig. 2(B)–(D)] indicate that Zn_1−x−yMn_xCo_yTe NCs are magnetic in a direction parallel (antiparallel) to the tip magnetization^{11,13–15,21} as shown by the N/S scale bar on the right side of Fig. 2(A)–(D). In this study, the magnetic phase images (MFM) were achieved after topography measurements (tapping mode), followed by sample surface scanning at the order of hundreds nanometers height (lift mode). Thus, no van der Waals forces were expected to be detected, and any change in the vibration amplitude of the cantilever was proportional to the gradient of magnetic fields perpendicular to the sample surface.²² Then, the results obtained by MFM images are a clear evidence of the substitutional incorporation of Mn²⁺ and Co²⁺ ions in ZnTe NCs (forming Zn_1−x−yMn_xCo_yTe NCs). It is worth noting that no MFM contrast was observed in the samples containing pure ZnTe NCs (Fig. 2(A)). This difference can be attributed to the fact that pure ZnTe NCs do not present any magnetic activity induced by the tip magnetization.

To evaluate the crystallographic characteristics of the as-synthesized Zn_1−x−yMn_xCo_yTe NCs in terms of Co y-content, we recorded XRD patterns of representative samples, namely x = 0.010 and y = 0.000 (Co undoped), 0.005, 0.050, 0.200 and 0.800, displayed in Fig. 3. The XRD diffractogram of the pure PZABP sample is also displayed in Fig. 3. Undoubtedly, the amorphous characteristic of the host glass matrix in which the NCs are embedded hinders observation of the NC XRD diffraction peaks. The XRD pattern of the PZABP glass matrix (black pattern in Fig. 3) shows an amorphous band at around 20 < 2θ < 30 degrees, confirming the glassy characteristics. The amorphous band related to the PZABP glass matrix is also present in the XRD patterns of the Zn_1−x−yMn_xCo_yTe NCs. More specifically, for the Zn_1−x−yMn_xCo_yTe NC samples, where we can observe the typical (1 1 1), (2 2 0), and (3 1 1) diffraction peaks of ZnTe with cubic zinc blende (ZB) structure (JCPDS: 15-0746).^23,24 This strongly indicates that the substitutional incorporation of Co²⁺ ions into Zn_1−x−yMn_xCo_yTe NCs does not change the lattice parameter and therefore the same ZB structure remains unaltered. This result is expected, since the ionic radii of Zn²⁺ (0.68 Å),²¹ Mn²⁺ (0.75 Å)²⁵ and Co²⁺ (0.72 Å)²⁶ are not very different. Furthermore, characteristic peaks of Te in a trigonal structure (JCPDS: 36-1452)²⁷ and TeO₂ in a tetragonal structure (JCPDS: 11-0693)²⁸ are also observed. The crystalline phases (Te and TeO₂) may have formed during the thermal annealing process.

Fig. 3 XRD patterns of pure PZABP glass matrix sample and of samples containing Zn_1−x−yMn_xCo_yTe NCs, with x = 0.010 and y = 0.000, 0.005, 0.050, 0.200 and 0.800. The standard card of zinc blende phase of ZnTe, with trigonal Te and tetragonal TeO₂, is displayed for comparison.

The XRD pattern also shows a broadening of the band in the region around 20 < 2θ < 30 degrees with increasing Co concentration. This is a characteristic of amorphous systems and can be related to the disorder caused by Co²⁺ ions in the host glass matrix.

Raman spectra of the as-grown Zn_1−x−yMn_xCo_yTe NCs revealing transitions at approximately 214, 323 and 428 cm⁻¹, are displayed in Fig. 4. The Raman modes correspond to the normal phonon modes that are typical of the ZnTe phase with cubic ZB structure: (i) first order longitudinal optical (1LO);²⁹ (ii) third order transverse/longitudinal optical coupled to the first order longitudinal acoustic (TO/LO + LA);³⁰ (iii) second order longitudinal optic (2LO).²⁹

Fig. 4 Raman spectra of Zn_1−x−yMn_xCo_yTe NC samples.

The Raman data in Fig. 4 reveal that the relative intensity of the main Raman peaks assigned to the as-grown Zn_1−x−yMn_xCo_yTe NCs (1LO and 2LO) decreases as Co y-content increases. This is a strong indication that the disorder caused in the glass system by high concentrations of Co²⁺ ions (as seen in the XRD patterns), is greater than the nucleation rate for the formation of Zn_1−x−yMn_xCo_yTe NCs, which inhibits the growth of these NCs.

The EPR spectra of pure PZABP matrix sample and of samples containing Zn_1−x−yMn_xCo_yTe NCs with Mn-doping nominal content x = 0.010 and Co-doping nominal content y varying from 0.000 to 0.800, are displayed in Fig. 5. The transitions observed satisfy the selection rules ΔM_S ± 1 and ΔM_I = 0, for both Mn²⁺ (B) and Co²⁺ (C) ions. No EPR signal was detected in the spectrum of the pure PZABP matrix, indicating that the host material used in the present study was free from paramagnetic impurities.

Fig. 5 (A) Room temperature EPR spectra of Zn_1−x−yMn_xCo_yTe NC samples with Mn-doping content x = 0.010 and Co-doping content y varying from 0.000 to 0.800. For both Mn²⁺ (B) and Co²⁺ (C) ions the transitions observed satisfy the selection rules ΔM_S ± 1 and ΔM_I = 0. No resonance signal was observed for pure PZABP glass samples.

The six absorption lines in the spectrum (Fig. 5(A)) of sample containing Zn_1−x−yMn_xCo_yTe NCs (with x = 0.010 and y = 0.000) result from the hyperfine interaction between the electron spin (S = 5/2) and the nuclear spin (I = 5/2) of Mn²⁺ ions. These absorptions are due to transitions between electronic states M_S = ±1/2 obeying the selection rules ΔM_S = ±1 and ΔM_I = 0,³¹ as shown by the energy diagram of Fig. 5(B). This spectrum reveals the presence of paramagnetic Mn²⁺ ions in all samples and is a conclusive evidence of the successful doping of these ions in the ZnTe crystal lattice, as it has been reported in our previous work.¹⁴ Furthermore, the sextet of lines of the samples containing Zn_1−xMn_xTe NCs can be interpreted as the sum of two sextets, as shown in Fig. 5(B). These two sextets, which have different hyperfine interactions and g-factors arise from Mn²⁺ ions incorporated into different sites in the Zn_1−xMn_xTe NCs.¹⁴ This in turn favors strong exchange interactions between electrons of the 3d sublevel of the Mn²⁺ ions and electrons of the sp sublevel of the host semiconductor. As a result of this, the hyperfine interaction parameters and the g-factors are A_I = 90 Oe and g_I = 2.005 for Mn²⁺ ions inside the NC (S_I sign of the simulated spectrum); and A_II = 95 Oe and g_II = 2.010 for Mn²⁺ near the surface of the NC (S_II sign of the simulated spectrum).

The spectra in Fig. 5(A) also reveal that as the Co doping concentration increases, the intensity of a broad background resonance line increases simultaneously with the decrease of the hyperfine lines. The linewidth of this broad line extends over the whole Mn²⁺ spectrum and is a result of the collapse of the hyperfine lines. As we have shown in other works, this broad line is attributed to interacting Mn²⁺ ions dispersed in the glass matrix.^14,21 This implies, therefore, that the growing concentration of Co²⁺ ions affects the incorporation of Mn²⁺ ions into the ZnTe NCs, increasing their dispersion throughout the glass matrix. This conclusion is supported by reports in the literature revealing that practically the same energy is necessary to incorporate Co and Mn atoms into the structure of ZnTe NCs, replacing Zn atoms, and also that this energy decreases with the concentration of the transition ion doping.^32,33

The EPR spectra of Fig. 5(A), in addition to the hyperfine lines and the broad background line due to the Mn²⁺ ions, also display an intense central line. This central line has factor g = 2.012 and is attributed to Co²⁺ ions dispersed throughout the glass matrix, not incorporated within the NCs.^34,35 It is also observed when the matrix is doped only with Co²⁺ ions, as can be seen in Fig. 5(C) by comparing the spectra of PZABP:0.05Co and Zn_1−x−yMn_xCo_yTe NCs (with x = 0.010 and y = 0.050) samples. This result is in good agreement with those given by OA, XRD and Raman scattering of samples doped with Co²⁺ ions.

The intense central line can be related to the spin–spin interactions between electrons of neighboring Co²⁺ ions.^34,35 It is indeed the result of the collapse of the eight hyperfine lines attributed to the allowed transitions between the M_S = ±1/2 electronic states, and due to the interaction between the electron spin (S = 3/2) and the nuclear spin (I = 7/2) of Co²⁺ ions (3d⁷). Strong evidence of this is given by the linewidth of about 120 Oe of the resonance line of PZABP:0.05Co sample displayed in Fig. 5(C) in agreement with known values of Oe of Co²⁺ hyperfine constant.^34,36,37 Reports in the literature reveal that the paramagnetic hyperfine lines of isolated Co²⁺ ions can be observed only at low temperatures.^34–37 At liquid helium temperatures, spectra of Co²⁺ doped ZnO structures displaying eight symmetrical resonance lines give a hyperfine constant of about 3.0 Oe.^34,38 However, asymmetrical hyperfine lines superposed to a very broad background line (exhibiting a linewidth of about 800 Oe) have also been observed for Cd_1−xCo_xS quantum dots,³⁵ reflecting clearly the high distortions of the sites occupied by the Co²⁺ ions.

4. Conclusions

Co²⁺ and Mn²⁺ doped ZnTe nanocrystals were successfully grown in a PZABP glass matrix that had been synthesized by the melting method after appropriate heat treatment. The physical properties of these NCs were studied by OA, AFM/MFM, XRD, Raman scattering and EPR spectroscopy. OA spectra give evidence of substitutional incorporation of Co²⁺ ions in tetrahedral sites of the semiconductor nanocrystals; at high concentrations Co²⁺ ions are also dispersed into the glass matrix, causing structural disorder. AFM images reveal the nanocrystals size and MFM shows that the samples doped with paramagnetic ions are magnetically responsive to the magnetization of the probe. This result is further proof of substitutional incorporation of Co²⁺ and/or Mn²⁺ ions in ZnTe nanocrystals. XRD patterns reveal that the Co concentration contributed to increase the structural disorder of the host glass matrix; this result is in good agreement with the OA, Raman scattering and EPR spectroscopy. The EPR spectra, in particular, reveal the overlapping of the hyperfine lines due to Mn²⁺ ions inside and at the surface of the ZnTe nanocrystals, a broad background line due to Mn²⁺ dispersed into the glass matrix, and an intense central line with g = 2.012 attributed to interacting Co²⁺ ions also dispersed into the glass matrix. Moreover, the EPR spectra reveal that the increase of Co doping reduces the incorporation of Mn²⁺ into the ZnTe nanocrystals, suggesting that there is a kind of competition between Co²⁺ and Mn²⁺ ions to substitute Zn²⁺ ions. This competition is controlled by the Co concentration.

Acknowledgements

We gratefully acknowledge financial support from the Brazilian Agencies: Conselho Nacional de Desenvolvimento Científico e Tecnológico-CNPq, Fundação de Amparo à Pesquisa do Estado de Minas Gerais-FAPEMIG, and Programa Nacional de Pós Doutorado da Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (PNPD CAPES) – Instituto de Física (INFIS), Universidade Federal de Uberlândia (UFU). We are also grateful for use of the AFM/MFM Shimadzu device at INFIS – UFU.

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