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Understanding the effects of heavy ion irradiation is significant for materials and devices applied in the field of nuclear radiation detection. In this paper, the relationship between heavy ions (20 MeV Cl) and electric performance in CdZnTe crystals has been investigated. A damage layer is introduced 6 μm below the CdZnTe crystal surface and dominated by donor defects according to the SRIM (stopping and range of ions in matter) calculation and Hall effect results. The current–voltage (I–V) is asymmetrical, which is attributed to the n+/n homojunction formed by the damage layer. The barrier height of the homojunction increases from 0.845 to 0.946 eV with radiation fluence. For low irradiation fluences, the I–V curves follow the Schottky emission model at a bias of 0–100 V because of barrier lowering due to the applied field and the image force. When the irradiation fluence is greater than 2.5 × 1012 n cm−2, the increasing leakage current after 40 V voltage conforms to the Poole–Frenkel (PF) effect caused by deep traps. The carrier mobility largely decreases from ∼1100 cm2 V−1 s−1 to 267–658 cm2 V−1 s−1 due to the scattering of ionized impurities. The energy resolving capability of γ-rays deteriorates from ∼8% to 15.3–26.8% by the trapping effect. The photopeak of the γ spectrum could not be recognized when the fluence reached 1.4 × 1013 n cm−2. This work provides important irradiation protection reference data for CdZnTe devices in various high-fluence application fields, such as industrial monitoring and nuclear spectroscopy. [ABSTRACT FROM AUTHOR]

Zn1−xMgxTe crystal is expected to be less harmful, more efficient, and economical as a blue-green LED material. In this study, Zn1−xMgxTe and P:Zn1−xMgxTe crystals with different x (0.06 ≤ x ≤ 0.25) values were prepared by the travelling Te solution method. The required polycrystalline materials for crystal growth were successfully synthesized by an element direct reaction method. The XPS results demonstrate that the Mg element is present in Zn1−xMgxTe polycrystalline as Mg2+. The lattice constants of zinc-blende Zn1−xMgxTe are approximately linearly dependent fitted as α(x) = 6.107 + 0.18x (Å). The Mg content dynamic equilibrium between the source materials, Te solution and crystal was anticipated to be progressively achieved throughout the crystal growth and then the segregation of the Mg in the as-grown crystal is reduced. The ranges of fluctuations in the Mg contents for Zn0.90Mg0.10Te and Zn0.75Mg0.25Te were 0.092–0.104 and 0.212–0.227, respectively, along the radial direction. When compared to the calculated values found in the literature, there is less axial segregation of the Mg component during the crystal growth. The Mg content along the axial direction of the crystal of Zn0.82Mg0.18Te increases at a rate of around 0.0047 cm−1, which is significantly less than that of Zn0.80Mg0.20Te crystal grown by the melting method (0.028 cm−1). As-grown Zn0.90Mg0.10Te and Zn0.75Mg0.25Te crystals have infrared and UV-vis-NIR transmittance values close to 60%, and their bandgaps are between 2.2 eV and 2.4 eV, respectively. The resistivity of intrinsic Zn0.75Mg0.25Te crystals is as high as 1.62 × 108 Ω cm. The lowest resistivity of P:Zn0.92Mg0.08Te crystals with p-type conduction is 28.6 Ω cm, and the greatest hole concentration is 8.02 × 1016 cm−3, according to the results of the Hall test. [ABSTRACT FROM AUTHOR]

Diamond possesses extremely excellent properties, which make it a potentially transformative material in an extensive range of applications. Herein, diamonds were synthesized in a FeNiCo–C system with B2S3 as an additive by a temperature-gradient growth method at high temperature and high pressure (HPHT) conditions. The effects of the B2S3 additive in the FeNiCo–C system on diamond crystallization were characterized using Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements. FTIR result shows the presence of positive-charged N+ in the diamond crystal synthesized with the B2S3 additive, and its concentration was estimated to be around 30 ppm. Moreover, the XPS measurements confirm that N+ can combine with boron to form a B–N bond. Furthermore, the Hall effect result indicates that the resistivity of the diamond crystal synthesized with B2S3 was reduced to 3.89 × 10 Ω cm, whereas, the resistivity of the diamond synthesized with the same weight of B2S3 additive along with Ti/Cu as the nitrogen removal agent dropped sharply to 2.51 × 10−1 Ω cm. [ABSTRACT FROM AUTHOR]

We adopted TiO2 seed layers for thin-film growth of anatase Ti0.95Co0.05O2−δ, a room-temperature ferromagnetic semiconductor, on rigid and flexible (ultrathin) glass substrates. The Ti0.95Co0.05O2−δ thin films with preferred (101) orientation and large crystallographic domains around 50 μm in lateral size showed clear ferromagnetic hysteresis loops in the magnetization curves at 300 K. In addition, their high electrical conductivity and transparency allowed electrical and optical detection of the ferromagnetic signal via the anomalous Hall effect and magneto-optical effect, respectively. Intriguingly, flatter thin films with larger domains were obtained on flexible glass substrates, which were beneficial to achieve higher conductivity and larger anomalous Hall signals, comparable to those in epitaxial thin films. [ABSTRACT FROM AUTHOR]

Recent discoveries of intrinsic ferromagnetism in low-dimensional ultrathin crystals offer a unique platform for investigating the basics of magnetism and fabricating devices that make use of spins. Here, we report the growth of Cr2.70Se0.60Te3.40 crystals by the chemical-vapour-transport technique. These crystals exhibit ferromagnetism with Curie temperature ∼ 245 K and magnetic moment ∼ 7.15 emu g−1. The nanosheets of Cr2.70Se0.60Te3.40 single crystals possess intrinsic ferromagnetism verified by the anomalous Hall effect, showing the great potential of Cr2.70Se0.60Te3.40 crystals for the fabrication of spintronic, data storage and topological devices. [ABSTRACT FROM AUTHOR]

We synthesized single and polycrystals of iron oxide with an unconventional Fe4O5 stoichiometry under high-pressure high-temperature (HP–HT) conditions. The crystals of Fe4O5 had a CaFe3O5-type structure composed of linear chains of iron with octahedral and trigonal-prismatic oxygen coordinations. We investigated the electronic properties of this mixed-valence oxide using several experimental techniques, including measurements of electrical resistivity, the Hall effect, magnetoresistance, and thermoelectric power (Seebeck coefficient), X-ray absorption near edge spectroscopy (XANES), reflectance and absorption spectroscopy, and single-crystal X-ray diffraction. Under ambient conditions, the single crystals of Fe4O5 demonstrated a semimetal electrical conductivity with nearly equal partial contributions of electrons and holes (σn ≈ σp), in line with the nominal average oxidation state of iron as Fe2.5+. This finding suggests that both the octahedral and trigonal-prismatic iron cations contribute to the electrical conductivity of Fe4O5via an Fe2+/Fe3+ polaron hopping mechanism. A moderate deterioration of crystal quality shifted the dominant electrical conductivity to n-type and considerably worsened the conductivity. Thus, alike magnetite, Fe4O5 with equal numbers of Fe2+ and Fe3+ ions can serve as a prospective model for other mixed-valence transition-metal oxides. In particular, it could help in the understanding of the electronic properties of other recently discovered mixed-valence iron oxides with unconventional stoichiometries, many of which are not recoverable to ambient conditions; it can also help in designing novel more complex mixed-valence iron oxides. [ABSTRACT FROM AUTHOR]

This article is dedicated to synthesizing pure ZnO and Rb-doped ZnO nanoparticles, RbxZn1-xO-NPs (x=0.0, 0.02, 0.04, 0.06 mol), using sol--gel technology. Synthesized samples have been characterized and studied using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and field-emission scanning electron microscopy (FE-SEM) analysis. The X-ray diffraction study confirmed that RbxZn1-xO ONPs have a hexagonal wurtzite polycrystalline structure with the space group C6v4-P63mc. XRD studies showed that increasing the Rb concentration leads to a decrease in the observed intensity of diffraction lines; in addition, these lines are slightly shifted towards lower diffraction angles. The texture coefficient (TC) values, degree of crystallinity values, and crystalline and non-crystalline phase percentages of RbxZn1-xO-NPs were also investigated and discussed analyzing the area under each diffraction peak. The microstructural parameters (crystallite size, D, and average microstrain, <ε>)of Rb--ZnO-NPs were also determined using the Scherrer equation, the Williamson--Hall (W--H) method, and size--strain plots (SSPs) applying the Lorentzian distribution (LD) and Gaussian distribution (GD) to compute the net broadening of diffraction lines. Using the GD and W--H methods, which were the best, it was found that the -values decreased from 50.67 nm to 34.23 nm, while the <ε>-values increased from 1.43 x 10-3 to 3.48 x 10-3 when the Rb content increased from zero to 0.06 mol. The EDX findings demonstrated that the compositional element percentages of the RbxZn1-xO-NP samples are in good agreement with those selected. The particle sizes of these NPs range on average from 60 nm to 700 nm and decrease upon increasing the Rb concentration. Generally, the results confirm that the RbxZn1-xNPs obtained using the sol--gel technique are regular and uniform in shape and have fine and smooth surfaces. [ABSTRACT FROM AUTHOR]