Defects present in ZnO nanocrystals prepared by a wet chemical method have been characterized by photoluminescence (PL) and positron annihilation spectroscopy (PAS) techniques. The as-prepared sample was heat treated at different temperatures to obtain nanocrystals in the size range of 19–39 ... (Read more)

The wide-band-gap zinc oxide-based diluted magnetic semiconductors currently attract considerable attention due to their possible use in spintronic devices. In this work, we studied ZnO nanowire samples synthesized on 10×10 mm² a-plane sapphire substrates by high-pressure... (Read more)

We present the results of an electron paramagnetic resonance study of homogeneous single phase Zn_1−xMn_xO thin films with Mn concentrations varying between x=0.07 and x=0.34. Our results show antiferromagnetic (AF) coupling in the entire... (Read more)

The electronic structure of Zn_1−xCo_xO (x=0.02, 0.06, and 0.10) diluted magnetic semiconductors is investigated using soft x-ray emission spectroscopy and first-principles calculations. X-ray absorption and emission measurements reveal that most Co... (Read more)

Fe-doped ZnO nanocrystals are successfully synthesized and structurally characterized by using x-ray diffraction and transmission electron microscopy. Magnetization measurements on the same system reveal a ferromagnetic to paramagnetic transition temperature above 450 K with a low-temperature... (Read more)

We calculate the fine structure splitting of the near band edge donor-bound excitons in major cubic semiconductors using an approach inspired by an earlier one that consists in replacing the Morse potential by a Kratzer one, in order to account for the repulsion between the donor and the hole. A... (Read more)

Conduction band electrons in colloidal ZnO quantum dots have been prepared photochemically and examined by electron paramagnetic resonance spectroscopy. Nanocrystals of 4.6 nm diameter containing single S-shell conduction band electrons have g^*=1.962 and a room-temperature... (Read more)

The asymmetry doping problem has severely hindered the potential applications of many wideband gap (WBG) materials. Here, we propose a possible approach to overcome this long-standing doping asymmetry problem for WBG semiconductors. Our approach is based on the reduction of the ionization energies... (Read more)

Existing defect models for In₂O₃ and ZnO are inconclusive about the origin of conductivity, nonstoichiometry, and coloration. We apply systematic corrections to first-principles calculated formation energies ΔH, and validate our theoretical defect model against... (Read more)

Photoluminescence spectroscopy has been used to study single crystalline ZnO samples systematically annealed in inert, Zn-rich and O-rich atmospheres. A striking correlation is observed between the choice of annealing ambient and the position of the deep band emission (DBE) often detected in ZnO. In... (Read more)

High purity growth of polar surface dominated ZnO nanodisks was fabricated by introducing In ions in the raw material by thermal evaporation process without a catalyst. The nature of the sharp-contrast lines in the disks was investigated. The results suggested that the existence of sharp-contrast... (Read more)

Li-doped ZnO films were prepared by pulsed laser deposition. The carrier type could be controlled by adjusting the growth conditions. In an ionized oxygen atmosphere, p-type ZnO was achieved, with the hole concentration of 6.04×10¹⁷ cm^–3 at an optimal Li... (Read more)

The authors report the observation of both acceptor- and donorlike defects in ZnO by deep level transient spectroscopy. The observation is facilitated by using a p-n junction allowing the injection of holes and electrons. The junction is realized by implanting a n-conducting ZnO... (Read more)

The influence of spherical nanoindentation on the band edge and deep level emission of single crystal c-axis ZnO has been studied by cathodoluminescence (CL) spectroscopy and monochromatic imaging. Excitonic emission is quenched at the indent site and defect emission in the range of... (Read more)

We investigate photoluminescence from reproducible Li-doped p-type ZnO thin films prepared by dc reactive magnetron sputtering. The Li_Zn acceptor state, with an energy level located at 150 meV above the valence band maximum, is identified from free-to-neutral-acceptor transitions.... (Read more)

Low temperature (10 K) strong anti-Stokes photoluminescence (ASPL) of ZnO microcrystal excited by low power cw 532 nm laser is reported here. Energy upconversion of 1.1 eV is obtained in our experiment with no conventional nonlinear effect. Through the study of the normal photoluminescence and... (Read more)

Fe ions of dose 5×10¹⁶ cm^–2 were implanted at 200 keV into a-plane ZnO epitaxial films. The epitaxial quality of the postannealed samples was verified by x-ray diffraction -rocking curves and scans, whereas x-ray absorption spectroscopy identified the... (Read more)

We derive a simple expression for the average angular orientation distribution of ferromagnetic FePt particles in an applied field in thermal equilibrium. This system is closely related to the Langevin expression for paramagnetic susceptibility, which computes the average orientation of particles in... (Read more)

The self-diffusion coefficient of zinc in ZnO is derived as a function of the chemical potential and Fermi level from first-principles calculations. Density functional calculations in combination with the climbing image-nudged elastic band method are used in order to determine migration barriers for... (Read more)

Phosphorus-doped ZnO films were grown by molecular-beam epitaxy with a GaP effusion cell as dopant source. Three growth regions were identified to obtain ZnO films with different conduction types. In the oxygen-extremely-rich region, phosphorus-doped ZnO films show n-type conduction with... (Read more)

Donor-acceptor (D-A) pair spectra have been observed in the photoluminescence radiative recombination of selected donor bound exciton complexes in zinc oxide (ZnO) single crystals that have been ion implantation doped with H and Zn atoms and subsequently annealed in a nitrogen (N₂)... (Read more)

Raman spectra of (Mn, Co)-codoped ZnO films were investigated as functions of laser line and temperature. It is shown that the Raman shifts for different phonon modes exhibit redshift with temperature increasing, which can be attributed to the anharmonic effect in the material. Strong resonant Raman... (Read more)

Raman measurements have been performed on ZnO bulk materials implanted with 220 keV Mn⁺ ions with various doses from 10¹⁵ to 10¹⁷ cm². The results reveal two modes at about 230 and 523 cm^–1, respectively, which are not observed in... (Read more)

ZnO single crystals implanted with O⁺ and B⁺ ions were studied by positron annihilation and Raman scattering measurements. Positron annihilation results show that vacancy clusters are generated by implantation. For the B⁺-implanted sample, the vacancy clusters have a... (Read more)

The internal quantum efficiency (_int) of the near-band-edge (NBE) excitonic photoluminescence (PL) in ZnO epilayers was significantly improved by eliminating point defects, as well as by the use of ZnO high-temperature-annealed self-buffer layer (HITAB) on a ScAlMgO₄ substrate... (Read more)

Photoluminescence (PL) spectra of single-crystal ZnO bulk under hydrostatic pressure are studied using the diamond-anvil-cell technique at room temperature. The PL spectrum of ZnO single crystal taken at atmospheric pressure was dominated by a strong near-band-edge exciton emission. The emission... (Read more)

High-quality ZnO thin films have been grown by plasma-enhanced molecular-beam epitaxy on sapphire substrates. Free-exciton absorption and exciton-LO phonon absorption peaks are observed in the films at room temperature, indicating that the exciton states are stable even at room temperature. Three... (Read more)

Photoluminescence and positron annihilation spectroscopy have been used to characterize and identify vacancy-type defects produced in ZnO films grown on sapphire by metal-organic chemical-vapor deposition. The photoluminescence of the samples in the near band edge region has been studied, paying... (Read more)

Luminescence properties of ZnO films, which have been epitaxially grown on c-sapphire (0001) substrates by plasma-assisted molecular beam epitaxy, are investigated by means of different excitation sources and their measurement conditions. With the increase of measurement temperature,... (Read more)

ZnO–Sb2O3–B2O3 glasses containing different concentrations of MnO ranging from 0 to 1.0 mol% were prepared. A number of studies, viz. optical absorption, infrared and ESR spectra and magnetic susceptibility, were carried out as a function of manganese ion concentration. The analysis of... (Read more)

We calculate the exchange interaction parameters of a classical Heisenberg Hamiltonian for Mn-doped ZnO (Mn concentration between 5% and 20%) by an ab initio Korringa-Kohn-Rostoker coherent-potential-approximation method in the framework of density functional theory. A weak antiferromagnetic... (Read more)

Low temperature wavelength-modulated reflectivity measurements of isotopically engineered ZnO samples have yielded the dependence of their A, B, and C excitonic band gaps on the isotopic masses of Zn and O. The observed dependence is analyzed in terms of the band gap renormalization by zero-point... (Read more)

Li is present in hydrothermally grown ZnO at high concentrations and is known to compensate both n- and p-type doping due to its amphoteric nature. However, Li can be manipulated by annealing and ion implantation in ZnO. Fast, 20 ms flash anneals in the 900–1400 °C range... (Read more)

We present a crystal-field theory of transition-metal impurities in semiconductors in a trigonally distorted tetrahedral coordination. We develop a perturbative scheme to treat covalency effects within the weak ligand field case (Coulomb interaction dominates over one-particle splitting) and apply... (Read more)

Experimental studies of Zn_1−xCo_xO as thin films or nanocrystals have found ferromagnetism and Curie temperatures above room temperature and that p- or n-type doping of Zn_1−xCo_xO can change its magnetic... (Read more)

Contradictory results concerning the formation of a ferromagnetic state in Mn doped ZnO layers have been reported in the last years. We present the results of an electron paramagnetic resonance study on homogeneous single phase n-type conductive Zn_1–xMn_xO... (Read more)

p-type doping is a great challenge for the full utilization of ZnO as short-wavelength optoelectronic material. Due to a large electronegative characteristic of oxygen, the ionization energy of acceptors in ZnO is usually too high. By analyzing the defect wave-function character, we propose... (Read more)

High-quality single crystals of ZnO in the as-grown and N⁺ ion-implanted states have been investigated using a combination of three experimental techniques—namely, positron lifetime/slow positron implantation spectroscopy accompanied by theoretical calculations of the positron... (Read more)

The electron paramagnetic resonance signal of an exchange-coupled pair consisting of a shallow interstitial Li donor and a deep Na-related acceptor has been identified in ZnO nanocrystals with radii smaller than 1.5 nm. From electron nuclear double resonance experiments it is concluded that the... (Read more)

Using first-principles methods based on density functional theory within the local density approximation (LDA) we calculate the structural and electronic properties of wurtzite MgO, ZnO, and CdO, and discuss their similarities and dissimilarities with the corresponding Group-III nitrides AlN, GaN,... (Read more)

Considerable interest has developed in the potential use of II–VI oxides as electronic and optical materials. In several cases, alkali atoms have been suggested as dopants. We report on the theoretical and experimental investigation of infrared and vibrational properties of a Li-OH complex in... (Read more)

Density-functional theory (DFT) calculations of intrinsic point defect properties in zinc oxide were performed in order to remedy the influence of finite-size effects and the improper description of the band structure. The generalized gradient approximation (GGA) with empirical self-interaction... (Read more)

Hydrogen diffusion in single crystal and polycrystalline zinc oxide was investigated by deuterium diffusion and hydrogen effusion experiments. Deuterium concentration depth profiles were measured as a function of the passivation temperature, while in H effusion experiments the molecular hydrogen... (Read more)

We have performed density-functional theory calculations in conjunction with the climbing image nudged elastic band method in order to study the self-diffusion of oxygen in zinc oxide. To this end, we have derived the complete set of migration paths for vacancies as well as interstitials in wurtzite... (Read more)

The role of Pr doping on double Schottky barrier formations at ZnO single grain boundaries was investigated by the combination of current-voltage measurements, atomic-resolution Z-contrast scanning transmission electron microscopy, and first-principles calculations. Although Pr segregated to... (Read more)

We report on the magnetic properties of thoroughly characterized Zn_1-xCo_xO epitaxial thin films, with low Co concentration, x=0.003–0.005. Magnetic and EPR measurements, combined with crystal field theory, reveal that isolated Co²⁺ ions in... (Read more)

ZnO substrate crystals from two different sources, and epitaxial layers have been studied by SEM, AFM, photoluminescence and EPR. Although fabricated by the same growth principle, i.e. the hydrothermal technique, the substrates differ in terms of purity and structural quality. In the PL spectra of... (Read more)

Zn2SiO4:Mn2+ is one of the green light luminants used for cathode ray tubes of televisions. Recently, optical materials emitting strong visible light under lower energy excitation have been expected. To obtain new luminants of high quality, we prepared Mn ion doped ZnO–GeO2 glasses and glass... (Read more)

Different ZnO nanostructures (tetrapods, shells, rods, and highly faceted rods) were characterized by photoluminescence (PL) and time-resolved PL measurements. It was found that different nanostructures exhibit very different optical properties in terms of defect emission and decay times of the... (Read more)

A set of bulk ZnO samples implanted with O and Zn at various densities were investigated by photoluminescence. The implantation concentration of O and Zn is varied between 1×10¹⁷/cm³ and 5×10¹⁹/cm³. The samples were thermally treated in an... (Read more)

Zinc oxide crystals grown by the seeded chemical vapor transport method have been annealed in zinc vapor at 1100 °C for 30 min. These thermochemical reduction treatments produce a deep red coloration in the crystals and increase their n-type electrical conductivity. Electron paramagnetic... (Read more)

Polycrystalline Zn1 − xMnxO was synthesized by co-precipitation method with xvarying between 0.01 and 0.10. Although X-ray diffraction patterns show a typical würtzite structure with no additional peaks for all samples, Raman spectroscopy indicates the appearance of an additional mode in... (Read more)

ZnMnO nanoclusters were synthesized by the sol–gel method. The structural and magnetic characters were investigated. The XRD spectrum shows ZnMnO nanoclusters are hexagonal wurtzite structures and a small quantity of ZnMn2O4 phase is also present in the spectrum. The percentages of Zn and Mn... (Read more)

Differential scanning calorimetric studies, spectroscopic studies (viz., optical absorption, ESR, infrared spectra) and thermoluminescence studies of ZnF2–MO–TeO2 (MO=ZnO, CdO and PbO) glasses doped with different concentrations of chromium ions have been investigated. Results have... (Read more)

The structural, optical and magnetic properties of nanostructured ZnO films co-doped with cobalt and aluminium have been studied. The nanocrystalline films, with cluster sizes in range 50–100 nm, were deposited by pulsed laser ablation in a mixed atmosphere of oxygen and helium. The... (Read more)

Optical detection of electron paramagnetic resonance reveals the I=7/2 EPR spectrum of V²⁺ in the sharp photoluminescence (PL) lines often observed at ~6885 cm^–1 in ZnO, which have universally been assumed previously to arise from copper. An alternative model for... (Read more)

Electron paramagnetic resonance (EPR) and optical absorption spectra of vanadyl ions in zinc lead borate (ZnO–PbO–B2O3) glass system have been studied. EPR spectra of all the glass samples exhibit resonance signals characteristic of VO2+ ions. The values of spin-Hamiltonian parameters... (Read more)

Diluted magnetic semiconductors (DMS), systems formed by replacing cations of the host semiconductor material with transition-metal ions, are developed for further use in spintronics. A good combination as a DMS is Zn1−xMnxO due to the ZnO wide band gap (3.37 eV) and the matching ionic... (Read more)

We prepared ZnO nanostructures using chemical and thermal evaporation methods. The properties of the fabricated nanostructures were studied using scanning electron microscopy, x-ray diffraction, photoluminescence, and electron paramagnetic resonance (EPR) spectroscopy. It was found that the... (Read more)

The properties of ZnO tetrapod and multipod structures were investigated using scanning electron microscopy, x-ray diffraction, photoluminescence (PL), and electron paramagnetic resonance (EPR) spectroscopy. While there is relationship between g = 1.96 EPR and green PL in some of the samples,... (Read more)

Freeze-drying, as a cryochemical powder processing method is applied in the synthesis of ZnO submicrometer to nanosized powders. The process involves rapid freezing of the sprayed precursor solution, drying under vacuum by sublimation of the solvent and salt decomposition to oxide by thermal... (Read more)

Hole burning in and displacements of the magnetic-resonance absorption line of the electron spin of the shallow hydrogen-related donor in ZnO are observed upon resonant irradiation with microwaves at 275 GHz and at 4.5 K in a magnetic field of 10 T. These effects arise from an almost complete... (Read more)

High quality ZnO single-crystal films were doped with copper by thermal diffusion, and their luminescent properties were studied by cathodoluminescence spectroscopy. Doping with copper increases the intensity of the green-emission band of the cathodoluminescence spectrum, whose peak, width, and shape at 78 and 300 K remain unchanged. At 4.2 K, a pronounced phonon structure with a phonon energy of 72 meV is detected in the cathodoluminescence green-emission band of the doped samples. In this case, the phonon peaks feature a triplet fine structure instead of the doublet one generally observed. This feature is attributed to radiative recombination of acceptor excitons that are localized at copper atoms and interact with each one of the subbands of the ZnO valence band. An analysis of the experimental data on the film cathodoluminescence and comparative studies of luminescence and electron spin resonance in single crystals allow one to conclude that the uncontrollable copper impurity typically existing in ZnO is responsible for green-emission luminescence in this material. (Read more)

Electron paramagnetic resonance (EPR) has been used to investigate molecular nitrogen and isolated nitrogen acceptors in single crystals of ZnO. These samples were grown by the seeded chemical vapor transport method with N₂ added to the gas stream. A five-line EPR spectrum is observed at... (Read more)

Tungsten phosphate glasses mixed with the three different modifier oxides, viz. PbO, ZnO and CaO doped with Er2O3 were prepared. The glasses were characterised by X-ray diffraction spectra, electron microscopy and differential thermal analysis. Optical absorption and photoluminescence spectra of... (Read more)

ZnO nanocrystals with diameters ranging from 4 to 50 nm were prepared via a wet chemical method and post-growth annealing treatments. The electron paramagnetic resonance (EPR) spectra of the nanocrystals show the resonance of electron centers with g-value close to that of the shallow donors in bulk... (Read more)

A defect associated with Li in ZnO is reported. This is an optical system which absorbs strongly in the red part of the spectrum: a doublet, the zero phonon lines are at 1.884 and 1.879 eV, respectively. The chemical nature of the centre is identified through isotope substitution. This is the first... (Read more)

Electron paramagnetic resonance (EPR), photoluminescence, and infrared optical absorption have been used to investigate a ZnO crystal before and after a thermal anneal for 1 h in air at 900 °C. The sample was an undoped high quality crystal grown by the chemical vapor transport method. In... (Read more)

Nitrogen acceptors are formed when undoped single crystals of zinc oxide (ZnO) grown by the chemical-vapor transport method are annealed in air or nitrogen atmosphere at temperatures between 600 and 900 °C. After an anneal, an induced near-edge absorption band causes the crystals to appear... (Read more)

Infrared optical absorption has been used to study OH−impurities into congruent co-doped LiNbO3:Cr3+:ZnO crystals doped with different Zn2+ concentration. The OH− IR absorption spectra present three bands that can be associated with different OH− complex centres available in the... (Read more)

In this paper, ZnO ultrafine particles (UFPs) were prepared by the thermal decomposition method of the precursor, zinc carbonate hydroxide. The structure and properties of the as-prepared ZnO UFPs were studied using TEM, XRD, BET, SPS, ESR, Raman, XPS and UV–Vis absorption spectroscopy. It... (Read more)

We report on the differences in the defect structure of ZnO particles that take place at the grinding of powders of pure ZnO and mixture ZnO–SnO2. The defect structure formed was studied by electron paramagnetic resonance (EPR). The results demonstrate that a sequential two-stage thermal... (Read more)

Electron paramagnetic resonance and Hall measurements show consistently the presence of two donors ( D1 and D2) in state-of-the-art, nominally undoped ZnO single crystals. Using electron nuclear double resonance it is found that D1 shows hyperfine interaction with more than 50 shells of surrounding... (Read more)

Some paramagnetic superoxide ions detectable by electron paramagnetic resonance (EPR) can be generated on Au/ZnO catalyst by oxygen adsorption at room temperature as well as at 553 K. In both the cases, the O2− ions are present on the catalyst surface. The disappearance of the O2−... (Read more)

We prepared ZnO ultrafine particles (UFPs) by thermal decomposition of the precursor zinc carbonate hydroxide. The surface properties of the as-prepared particles were studied using TEM, XRD, BET, SPS, EPR, IR, and XPS. The surface contains active species such as oxygen deficiencies and hydroxyl... (Read more)

We have used EPR and ODMR to study state-of-the-art bulk ZnO single crystals. Most of the samples are n-type; however, under certain conditions (e-irradiated or annealed), we observe a center due to residual nitrogen (g||=1.9953, g=1.9633 and Aiso=1.225 mT, Aaniso=0.864 mT). The N center is a... (Read more)

The mixed MoO3–ZnO catalyst was expected to reveal the new function as a catalyst. The catalyst was characterized by XRD, ESR, XANES and so on. We found that the MoO3–ZnO catalyst was effective for isomerization and metathesis of 1-butene. The defects with the anion vacancy were formed... (Read more)

The method of doping trivalent metal ions into a copper-based catalyst for methanol synthesis is effective in modifying the surface structure of the catalyst. The promotion effect and its relation to catalytic activity for hydrogenation of CO to methanol after doping with trivalent metal ions such... (Read more)

ZnO polycrystals doped with Li, Cu or Al were prepared by solid-state reactions and their cathodoluminescence (CL) and electron spin resonance (ESR) spectra were measured. A strong yellow emission centered at 2.0 eV was observed for the Al-doped specimen and its intensity was higher than that of... (Read more)

Electron Paramagnetic Resonance (EPR) experiments have been carried out on congruent crystals of LiNbO3 heavily doped with Mg or Zn and co-doped with Er. In addition to the EPR spectrum previously observed in crystals of LiNbO3:Er3+ an erbium spectrum not reported before is detected in samples... (Read more)

It has been found that zinc borosilicate glasses 60ZnO–20B2O3–20SiO2 doped with 0.2 mol% Tb2O3 exhibit phosphorescence after exciting with 254 nm light. This phosphorescence arises from f–f transitions of Tb3+ ions and is observable by the eye, in the dark for up to 1 h after... (Read more)

The preparation of ZnO microcrystallites using a microemulsion method and their electron spin resonance (ESR) properties are reported for the first time. It was found that the ZnO microcrystallite exhibits an ESR signal at room temperature, in contrast to that of bulk ZnO. The results confirmed that... (Read more)

By combining electron paramagnetic resonance (EPR), optical absorption, and photoluminescence (PL) spectroscopy, a strong correlation is observed between the green 510 nm emission, the free-carrier concentration, and the density of singly ionized oxygen vacancies in commercial ZnO phosphor powders.... (Read more)

We explore the interrelationships between the green 510 nm emission, the free-carrier concentration, and the paramagnetic oxygen-vacancy density in commercial ZnO phosphors by combining photoluminescence, optical-absorption, and electron-paramagnetic-resonance spectroscopies. We find that the green... (Read more)

ZnO and CdSe crystals have similar hexagonal wurtzite structures with a contraction along the c-axis of the crystal, but contrary electronic fine structures for ZnO:Mn2+ (D < 0) and CdSe:Mn2+ (D > 0) have been found in EPR experiments. We demonstrate that the ground-state splitting in ZnO:Mn2+... (Read more)

Electron paramagnetic resonance (EPR), optical absorption, and photoluminescence (PL) spectroscopy have been combined to characterize Pb-doped ZnO ceramic powders. We observe a decrease in the 2.26 eV emission peak and a concomitant smearing of the band edges, narrowing the effective gap of the... (Read more)

The additions of NiO (0–2.0 mol%) to ZnO result in a decrease of the parameter c of its crystal lattice and its high-frequency electrical conductivity and in an elimination of the ESR band with g = 1.96. The observed changes were ascribed to the formation of Zn1−xNixO solid solution,... (Read more)

This paper describes the application of a new technique-Microwave Hall Effect (MHE) measurements-to measure electron mobilities and to determine the effect of adsorption on electron densities of powders. Conduction electron densities calculated from microwave measurements of both mobilities and... (Read more)

Microwave-Hall-effect (MHE) and electrical conductivity measurement techniques can now be used to obtain absolute values of the electrical properties of semiconductor powders under different controlled conditions. A commercial ESR spectrometer was modified to conduct MHE experiments and a network... (Read more)

Investigations have been made on the effects of pulse laser annealing on the ceramics (Zn,Mn)O by means of electron spin resonance (ESR) measurements. A remarkable change in the ESR spectrum was observed after annealing by a Nd:YAG pulse laser (=1.064 µm, 5–7 J/cm²). It... (Read more)

Surface and bulk defects in ZnO were recognized as interstitial zinc atoms and surface oxygen vacancies (V0)s by means of XRD, SEM, TPD and ESR measurements. Dispersion of ruthenium at the ZnO surface induces an electron transfer from ZnO defects to the metal as revealed by ESR and XPS spectroscopy. (Read more)

UV-induced optical and ESR absorptions of borosilicate glasses containing a large amount ( 50 mol%) of CdO or ZnO were measured at room temperature and 77 K while changing the wavelength of the illuminating light. The induced optical absorption was one order of magnitude stronger at 77 k than at... (Read more)

The ZnO/ZnCr2O4/Pd mixture is an effective catalyst for the preparation of pyrazines from diamines and glycols. The effects of the method of preparation, the Zn/Cr ratio, and the concentration of Pd have been studied by analyzing the catalyst structure using several techniques. In the coprecipitated... (Read more)

Binary Cu---ZnO catalysts active for methanol synthesis and the CO shift reaction were studied by EPR and by adsorption calorimetry. The EPR spectrum of Cu(II) in the calcined catalyst (CuO---ZnO) was studied, and also its evolution on reduction of the calcined into the reduced form... (Read more)

A detailed atomistic understanding of charge transfer reactions between semiconductor surfaces and adsorbing particles is essential for designing gas sensors or metal-oxide catalysts.This will be demonstrated in a discussion of thermodynamically or kinetically controlled solid/gas interactions at... (Read more)

The ZnO samples were prepared by firing at 900°C, finely powdered material under different degrees of reduction. Measurements of the green cathodoluminescence (CL) were done by using a vacuum fluorescent display. The g values of ESR spectrum measured from the powders at 77 K were g|| =... (Read more)

Shallow donors in ZnO were studied by electron spin resonance (ESR) and optically detected magnetic resonance (ODMR). Indium and gallium donors were identified by their hyperfine structure. They have g|| = 1.957 and g = 1.956 and the hyperfine constants are A(69Ga)=4.2 and A(115In)=36.6 G. The ESR... (Read more)

Lower oxydation state chromium species which are successively formed and stabilized upon thermal reduction of chromate (VI) ions, are studied by combined EPR and TG-techniques.The spontaneous oxygen release occuring during the vacuum thermal treatment of some zinc chromates leads to the formation of... (Read more)

Investigations are reported on the reaction of oxygen with electrostatic neutral ZnO–100-surfaces studied by means of AES, LEED, EPR, thermal desorption spectroscopy, and isotopic exchange as well as changes in the surface conductivity and work function. Geometric and electronic structures of... (Read more)

At low temperatures, the EPR signal of a Cu2+ center is observed in ZnO single crystals doped both with copper and hydrogen. A clear effect of line narrowing on the copper hfs-lines is observed at T=16K. It is discussed in the model of a Cu-(OH) complex taking into account the thermally induced... (Read more)