ZnSe Powder Research Articles

Development and characterization of novel Fe2+:ZnSexS1-x solid solution laser ceramics for mid-infrared laser application

In this study, Fe2+:ZnSexS1-x (0.6 ≤ x ≤ 1) solid solution laser ceramics with cubic crystal structures were prepared for the first time via hot pressing sintering, using FeSe, ZnSe, and ZnS powders. The resulting ceramics exhibit a unique combination of the optical and physical properties of Fe2+:ZnSe and Fe2+:ZnS. An increase in the ZnS content led to a blueshift in the maximum absorption spectra of Fe2+ ions and an enhancement in Vickers hardness. These findings suggest that Fe2+:ZnSexS1-x solid solution ceramics could serve as promising gain media for mid-infrared solid-state lasers, offering a novel approach for the development of directly pumped mid-infrared laser systems.

Spectroscopic and electrical analysis of p–Si/n-ZnSxSe1−x (0.0 ≤ x ≤ 1.0) heterostructures for photodetector applications

The present paper focuses on the properties of the p–Si/ ZnSxSe1−x (0 ≤ x ≤ 1) heterojunctions in photodetector applications. The heterostructures were fabricated by depositing ZnSSe on Si wafer using the thermal co-evaporation technique with ZnS and ZnSe powders. The GIXRD study showed that films were in cubic phase, and the prominent peak was shifted with composition x. The maximum crystallite size of the films was found for x = 0.8. The presence of point defects and emission related to higher Zn content in the thin films was confirmed by Photoluminescence. Temperature-dependent Raman analysis reveals that the longitudinal optical phonon modes shift to the lower wavenumber side as temperature decreases, which describes the variation of lattice parameters with temperature. The barrier height and ideality factor were calculated by implementing the thermionic emission. The photoresponse of p–Si/ ZnSxSe1−x heterostructures was studied. The investigation showed that the sample with x = 0.8 exhibits high photosensitivity and is suitable for photodetector applications.

Antibacterial Activity of ZnSe, ZnSe-TiO2 and TiO2 Particles Tailored by Lysozyme Loading and Visible Light Irradiation.

ZnSe, ZnSe-TiO2 microspheres and nanostructured TiO2 obtained by hydrothermal and sol-gel methods were tested against Staphylococcus aureus ATCC 25923 and Micrococcus lysodeikticus ATCC 4698 before and after lysozyme (Lys) loading. Morphological characterization of inorganic matrices and hybrid organic-inorganic complexes were performed by microscopy techniques (SEM, AFM and Dark Field Hyperspectral Microscopy). Light absorption properties of ZnSe, ZnSe-TiO2 and TiO2 powders were assessed by UV-visible spectroscopy and their ability to generate reactive oxygen species (•OH and O2•-) under visible light irradiation was investigated. Antibacterial activity of ZnSe, ZnSe-TiO2, TiO2, Lys/ZnSe, Lys/ZnSe-TiO2 and Lys/TiO2 samples under exposure to visible light irradiation (λ > 420 nm) was tested against Staphylococcus aureus and Micrococcus lysodeikticus and correlated with ROS photogeneration.

Role of powder handling on resulting impurities in ZnSe-doped As-S-Se composite materials

Optical composite materials made by powder processing routes can suffer from unwanted absorption loss introduced through powder handling. This can be due to impurities that are introduced during different stages of a powder processing protocol such as mixing, sieving, or grinding. The present work has evaluated the prevalence of impurities imparted to powders used to create an optical composite comprised of an As-S-Se chalcogenide base glass and ZnSe powders. The goal of this study was to identify a suitable powder handling protocol that demonstrates control of the starting particle sizes of the refractive index matched glass matrix and dopant ZnSe to acceptable levels and minimizes adverse impurities that can create loss in a glass-ceramic composite preform and envisioned fiber preforms, and fibers formed from them. Employing a heat treatment step under vacuum prior to re-melting glass powders was shown to reduce the concentration of key impurities, OH-, S-H, and Se-H, by 45.0%, 31.1% and 21.2%, respectively, as compared to re-melted material made from powders without specialized handling.

Effect of indium doping on the optoelectronic properties of ZnSe films

Polycrystalline In:ZnSe films were prepared by the thermal co-evaporation method, where high purity ZnSe and In2Se3 powders are taken as source materials. Orderly change in the X-ray diffraction peak position and red shift in the optical absorption edge have confirmed the incorporation of the dopant in the system. Photoluminescence spectra showed that the doped system has a Zn vacancy, which is in line with energy dispersive spectroscopy measurements. The chemical state of the doped films i.e., Zn2+, In3+ and Se2− was analysed by Raman and X-ray photoelectron spectroscopy (XPS); XPS has also indicated the incorporation of oxygen in small fractions which improves the conductivity of the films. The electrical investigation has revealed that electrical properties altered by doping and majority charge carriers are electrons and carrier density is in the order of 1015 cm−3. Films with 15 at. % In exhibited good photoresponse in the visible range and suitable for photodetector applications.

Hot-pressed Fe2+:ZnSe transparent ceramics with different doping concentrations

In this study, Fe 2+ :ZnSe transparent ceramics with different doping concentrations were prepared from annealed FeSe and ZnSe powders by hot pressing. The as-prepared ceramics consisted of a cubic ZnSe phase and compact microstructures. Doping concentrations of Fe 2+ ions in the range 0.66–3.05 at.% were accurately realised, which could influence the absorption intensity of Fe 2+ :ZnSe transparent ceramics. An absorption peak was observed at ∼3 μm, and its intensity could be controlled by the concentration of Fe 2+ ions. Fe x Zn 1- x Se (0.0066 ≤ x ≤ 0.0305) ceramics with Fe 2+ ions concentrations in the range 0.66–3.05 at.% exhibited significant absorption cross sections from 0.6676 × 10 −19 to 0.1075 × 10 −18 cm 2 . The specimen doped with 1.55 at.% Fe 2+ ions displayed the highest transmittance of 67% at a wavelength of 14 μm and a carbonate absorption peak at 9 μm. The proposed transparent ceramic technique appears promising for preparing Fe 2+ :ZnSe laser gain media because of its advantage of allowing control over Fe 2+ concentration.

Synergistically Modulating Geometry and Electronic Structures of a Chalcogenide Photocatalyst via an Ion-Exchange Strategy.

Maneuvering the architecture and composition of semiconductors is essential to optimizing their performance in photocatalytic solar-to-fuel conversion. Here, we show that ion exchange, having a disparate mechanism with direct nucleation and growth of semiconductor crystals, can provide a new platform for rational control over the geometry and electronic structures of chalcogenide semiconductor photocatalysts. As a demonstration, the ZnSe nanocubes possessing a hollowed architecture and doped with a controllable amount of Ag+ ions are accessed via sequential ion exchange. The kinetics of the exchange reaction offers a knob for regulating the electronic structures of the Ag-doped ZnSe hollow cubes and, hence, their functions in light harvesting and photogenerated charge separation. Such synergistically geometric and optoelectronic modulation of ZnSe brings an order of magnitude enhancement in photocatalytic H2 evolution activity relative to commercial ZnSe powders. Our study corroborates that ion exchange may open up new horizons for judicious fabrication and engineering of semiconductor-based photocatalyst materials.

Enhancement of ZnSe stability during optical composite processing via atomic layer deposition

This study evaluates the impact and stability behavior of a candidate protective shell of Al2O3 which aims to hinder the dissolution of ZnSe in As-S-Se glass systems during the so-called ‘grinding-remelt’ process. Atomic Layer Deposition (ALD) was chosen as the route to conformal shell coating and the role of resulting film attributes on powder and bulk composite properties were assessed to ascertain how ALD film attributes aided stability in the chalcogenide glass melt environment. It is shown that an ozone pre-treatment, performed on the ZnSe powders prior to the ALD, improves particle stability, resulting in a significant decrease of the dissolution behavior of coated powders. This enhanced stability increases with shell thickness and with the use of ozone pretreatment step on the powders. Coating chemistry and structure evaluated via XPS and HR-TEM illustrates the mechanism of dissolution for different ZnSe coated particles at varying loading levels in the glass matrix.

Atomic Layer Deposition (ALD) of Ultra-Thin Diffusion Barriers on ZnSe Microparticles for Phase Stability in Chalcogenide Glasses for Mid-Infrared Optics

ZnSe embedded chalcogenide glass (ChG) composites are optically active in the mid-infrared (IR) and are ideal for niche applications in medical diagnosis, military missile heat-sensing, and chemical identification. The embedded ZnSe crystals play a critical role in providing lasing activity while the ChG - As2S3-xSex matrix, acts as a host that can be drawn into fiber and provides the necessary mid-IR transparency. However, during synthesis, the ZnSe particles are prone to dissolution in the As2S3-xSex matrix due to a high temperature (650 oC) melting and homogenization process. Here we demonstrate that a thin amorphous barrier layer of Al2O3 deposited using atomic layer deposition (ALD) on ZnSe microparticles 5-10 mm in average diameter is successful to prevent ZnSe dissolution in the As2S3-xSex matrix even after extended melting and homogenization at 650 oC for 8 hours. This talk will highlight some of the key process innovations required to overcome challenges of ALD on powdered components for functionalizing and enhancing performance of multiphasic glasses for optical applications.Amorphous aluminum oxide (Al2O3) was deposited using alternate pulses of trimethyl aluminum and H2O on 1 gm batch size ZnSe using a customized rotary barrel reactor inside a viscous-flow ALD furnace attached to a quadrupole mass spectrometer (QMS). The temperature of deposition was kept at 180 oC and the number of cycles were varied from 100 to 300 cycles. The ZnSe particles were sieved to an average size of 5-10 mm and a maximum size ≤ 20 mm. The coated particles were characterized by x-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The crystallinity of the ZnSe-As2S3-xSex glasses were evaluated using x-ray diffraction (XRD) and their composition stability spatially mapped across individual ZnSe particles embedded in As2S3-xSex matrix using Raman microspectroscopy.Whereas 100 ALD cycles provide partial protection to dissolution for the ZnSe in As2S3-xSex, a 300 cycle ALD Al2O3 on ZnSe particles is sufficient to provide phase and composition stability to the ZnSe embedded As2S3-xSex glass. Through our investigation, we exemplify the efficacy and potential of ALD of ZnSe powder in improving the stability of optical materials while still achieving optimal mid-IR lasing and transparency.

Hot-pressed Fe2+:ZnSe ceramics with powders fabricated via grinding chemical vapor deposition ZnSe polycrystalline

In this work, Fe2+:ZnSe powders were prepared by grinding a mixture consisting of high-purity ZnSe obtained via chemical vapor deposition and thermally diffused Fe2+:ZnSe. In this manner, it was possible to avoid the presence of harmful H2Se gases and achieve homogeneous distribution of Fe2+ ions in the synthesis of Fe2+:ZnSe powders. Fe2+:ZnSe transparent ceramics were fabricated by hot-pressing as-obtained powders. Phase structure and microstructural properties of the powders and ceramics were studied via X-ray diffraction and field-emission scanning electron microscopy. As-prepared Fe2+:ZnSe ceramics exhibited dense microstructure with relative density higher than 99%, but few residual micropores were found to be localized at grain boundaries. 1.0-mm-thick Fe2+:ZnSe ceramic sintered at 900 °C showed the best optical transmission, namely ∼63% at 5 µm and ∼69% at 14 µm. Additionally, hot-pressed Fe2+:ZnSe ceramics displayed an absorption peak at around 3 µm. These Fe2+:ZnSe ceramics are promising candidates as mid-infrared laser gain materials.

Synthesis of nanograined ZnO nanorods functionalized with NiO nanoparticles and their enhanced hydrogen sensing properties

NiO nanoparticle (NP)-functionalized nanograined ZnO nanorods (NRs) were grown by using the thermal evaporation of ZnSe powders; this was followed by the thermal oxidation of the ZnSe NRs to synthesize ZnO NRs and a solvothermal process for NiO functionalization. The diameters of the grains in the synthesized nanograined ZnO NRs are in the range of 50–150 nm. The ZnO grains were not spherical, but they were shaped like rice grains. The diameters and the lengths of the ZnO NRs were in the range of 40–50 nm and 1–6 µm, respectively. The diameters of the NiO NPs were in the range of 40–80 nm. A multiple-networked chemiresistive sensor was fabricated by pouring the IPA solution containing NiO NP-decorated nanograined ZnO NRs onto SiO2/Si substrates with a patterned electrode. A pristine nanograined ZnO NR sensor was also prepared in a similar manner. The NiO NP-functionalized nanograined ZnO NR sensor exhibited a greater and faster response to H2, as compared to its pristine nanograined ZnO counterpart; it also showed higher selectivity toward H2 against other reducing gases, as compared to the pristine nanograined ZnO counterpart. Herein, the origin of the enhanced sensing performance of the NiO NP-functionalized nanograined ZnO sensor is discussed in detail.

Состав паровой фазы при испарении механической смеси порошков селенотеллуридов кадмия и цинка

The effect temperature has on the composition of a vapor phase passed through a thermal field after the evaporation of a mechanical mixture of the powders of cadmium and zinc selenotelluride is studied. It is found that the composition of the vapor phase can be changed throughout the range of concentrations by varying the temperature. The results of the study are satisfactorily explained by the effect temperature has on the particle distribution function in correspondence to the weights of the molecules constituting the mixture. There were virtually no molecules of the evaporated substance in the vapor phase, which consisted of diatomic molecules of the elements of Group VX compounds and metal atoms. This means that with the evaporation of mechanical mixtures of CdTe and CdSe powders, the vapor phase in the evaporator contains only Cd, Se2, and Te2 molecules, while mixtures of ZnTe and ZnSe powders contain Zn, Se2 and Te2 molecules. Despite the similarity between the components’ heats of sublimation, their concentrations over the powdermixture did not correspond to the composition of the powder mixture, since compounds A2B6 sublimate incongruently. Coming from the evaporator, the vapor phase entered the thermal field and was condensed onto a substrate at room temperature at its outlet. As follows from the composition of the substrate films, the vapor phase at the outlet was enriched with the light component Se, compared to the powder mixture. By virtue of the law of the conservation of mass, the vapor phase was therefore enriched with the heavy component Te at the inlet to the thermal field. Our results show that the thermal field controls the composition of the vapor phase by changing the particle distribution function according to the weight of the molecules constituting the mixture. The temperature dependences of the composition of the vapor phase are presented for several mechanical mixtures of the powders of (CdSe)x (CdTe)1-x and (ZnSe)x (ZnTe)1-x, where x = 0.45-0.90.

Effect of thickness on characteristics of ZnSe thin film synthesized by vacuum thermal evaporation

Zinc selenide (ZnSe) thin films with various thicknesses were grown on ultrasonically clean glass substrates using vacuum evaporation of 99.99% pure ZnSe powder. Thickness dependence of the structural, optical and electrical properties was thoroughly investigated. X-ray diffraction (XRD) analyses revealed that (110) ZnSe plane is the dominant crystal plane for all the fabricated films. Both dislocation density and micro-strain go down with the increase in film thickness, indicating lower lattice defects and improvement in crystallinity at higher film thickness. Transmittance spectra show that all the films have almost linear upward tendency of transmittance in near-infrared region and small fluctuations in visible region for higher-thickness films. With the increase in film thickness, the optical bandgap increases and also an increasing tendency of dielectric constant was observed. Studies of electrical properties showed a sharp increase in carrier mobility and concentration with film thickness. As the film thickness increases from 30 to 90 nm, the carrier mobility goes up from 255 to 1250 cm2/VS and the carrier concentration increases from 2.14 × 1018 to 9.37 × 1018 cm−3. The electrical transport properties of the deposited thin films were explained in terms of scattering of the charge carrier.

Microstructure development and optical properties of Fe:ZnSe transparent ceramics sintered by spark plasma sintering

ABSTRACTFe:ZnSe transparent ceramics were prepared by spark plasma sintering. Fe:ZnSe powders synthesized via co‐precipitation yielded well‐dispersed particles with an average particle size of 550 nm. These powders were in the cubic phase Fe:ZnSe, indicating the successful substitution of Fe2+ for Zn2+. The highest relative density, 99.4%, was obtained by increasing the pressure and sintering time. The effects of sintering temperature, pressure, and time on the microstructure of SPS prepared ceramics were presented by micrographs. With increasing sintering temperature, from 600°C to 900°C, the average grain size increased from < 1 to 10 μm. The intergranular fracture indicated no neck formation in the sintering process. High pressure was essential for the densification process. The average grain size deceased from approximately 10 to 5 μm when the pressure was increased. Increasing the sintering time from 10 to 120 minutes lead to a change in the microstructure, from inter‐ to transgranular fracture, and eliminated the micropores. The as‐prepared Fe:ZnSe ceramics were composed of single‐phased cubic ZnSe. The sample sintered at 900°C under a pressure of 90 MPa for 120 minutes yielded a transmittance of approximately 60% at 1.4 μm and 68% at 7.5 μm and had residual micropores as its main scattering source. There was a strong characteristic absorption peak of Fe2+ ions at around 3 μm, which was red‐shifted compared to Fe:ZnS transparent ceramics. Fe:ZnSe transparent ceramics have a reddish‐brown color and it could be a promising mid‐infrared laser material.

One-Step Synthesis of Enhanced Band-Edge Emission ZnSe Nanowires Assisted by SnO<SUB>2</SUB>

Zinc selenide (ZnSe) is a direct band gap semiconductor material with a band gap of 2.7 eV at room temperature, and is a very promising blue light emitting material. However, the ZnSe nanomaterials grown by the usual Au-catalyzed chemical vapor deposition (CVD) method are prone to cause defects in the material, and its luminescence spectra generally have strong yellow light emission, which seriously affects its application in blue light devices. The paper proposes a simple method for preparing blue light-emitting ZnSe nanowires. Adding a small amount of SnO2 to the source material ZnSe powder, when using the CVD method to grow ZnSe nanomaterials, can obtain ZnSe nanomaterials with only band edge blue emission. SnO2 can not only act as a catalyst, promote the growth of ZnSe nanowires and nanoribbons, reduce the growth temperature of nanomaterials, but also avoid the occurrence of deep level defects in ZnSe nanomaterials, and obtain pure blue light emitting ZnSe nanowires. The emission peak of the nanowire grown by this method can be shifted from 460 to 500 nm. By precisely regulating the growth of the nanowire, it can make it emit light to cover the entire blue region, which can promote the application of inorganic semiconductor nanomaterials in the field of lighting and display.

Tailoring the structural, electrical, optical and wettability properties of ZnSe films by oblique angle thermal evaporation

ZnSe films were prepared using thermal evaporation by keeping the substrates at angles of 0°, 60° and 75° with the horizontal direction. The film prepared at 0° had zinc-blende cubic crystal structure with an average crystallite size of 27 nm while the other two films showed very weak crystalline peaks due to the presence of a small amount of nano-crystallites. The Raman spectra of all the thin film samples show peaks at 256 cm−1 due to the longitudinal optical (LO) mode that is blue shifted as compared to the LO peak at 245 cm−1 in the commercial ZnSe powder sample. Globular structures protruding from the surface were observed in the FESEM and AFM images and the size of the globules decreased with an increase in the deposition angle. The root mean square surface roughness is 21 nm, 48 nm and 33 nm for films deposited at 0°, 60° and 75° respectively. The optical band gap is in the range: 2.71 to 2.75 eV and all the films were highly transparent in the mid-infrared region. The electrical conductivity increases with an increase in the deposition angle and the values are 4.84 × 10−9 ohm−1 cm−1, 9.51 × 10−9 ohm−1 cm−1 and 2.12 × 10−7 ohm−1 cm−1 (at 308 K) for the films deposited at 0°, 60° and 75° respectively. The water contact angle measurements found that the films grown at oblique angles have higher hydrophobicity as compared to the normally deposited film. The study elaborates the influence of oblique angle deposition in the modification of the structural, surface roughness, electrical, optical and wettability properties of ZnSe thin films.

Growth and characterization of ZnxSn1−xSe films for use in thin film solar cells

We have fabricated ZnxSn1−xSe (ZTSe) films for the first time. Samples were fabricated by chemical molecular beam deposition method at atmospheric pressure in hydrogen flow. ZnSe and SnSe powders with 99.999% purity were used as precursors. The temperature of precursors varied in the range of (850–950) °C. Films were deposited at substrate temperature of (500–600) °C. Borosilicate glass was used as a substrate. We have studied ZTSe films by EDS, XRD and SEM. The samples had orthorhombic and cubic structures depending on composition. Results of EDS have shown that stoichiometric composition of samples moved to ZnSe side by increasing with substrate temperature. SEM pictures have shown that samples had polycrystalline structure. The grain size varied in the range of (2–15) µm. The grain size of samples increased from (2–5) µm to (15–20) µm for substrate temperatures of 500 °C and 550 °C respectively. While, at a substrate temperature of 600 °C the grain size decreased up to (3–5) µm, possibly, because of increasing of ZnSe content. XRD analysis has shown that samples have ZnSe, SnSe, Se and Sn phases. The band gap of samples varied in the range of 1.0–2.0 eV depending on the film compositions. An inversion of the conductivity type was found: samples fabricated at 500 °C and 550 °C performed of p-type conductivity; while samples fabricated at 600 °C showed n-type conductivity.

Effect of Substrate Temperature on the Physical Properties of ZnхSn1 – хSe Films for Thin-Film Solar Cells

At the present time, 92% of the PV market is made using single crystal or polycrystalline wafer silicon. However, producing power with these cells remains expensive compared to conventional power generation. Thin film solar cells have been developed to reduce production costs, especially those based on cadmium telluride (CdTe) and copper indium gallium diselenide (CIGS). Despite a number of successes in the development of thin film solar cells, some problems associated with the toxicity of cadmium and with the high cost of indium and gallium remain, which has prompted researchers to search for alternative materials for solar cells. Novel low cost and high efficiency zinc tin selenide (ZnxSn1 – xSe) thin film solar cells are without these drawbacks. However, there is no information in the literature about this new material. The samples of ZnxSn1 – xSe films were fabricated using the chemical molecular beam deposition (CMBD) method at atmospheric pressure in hydrogen flow. ZnSe and SnSe powders with 99.999% purity were used as precursors. The temperature of precursors varied in the range of 850–950°C. Films were deposited at substrate temperature of 500–600°C. Borosilicate glass was used as a substrate. The results showed that the composition of the samples changed toward ZnSe with the temperature of the substrate. The grain size of the samples increased from 2–5 μm to 15–17 μm at substrate temperatures of 500 and 550°C, respectively. At a substrate temperature of 600°C, the grain size decreased to 3–5 μm, which is possibly due to an increase in the ZnSe content. The X-ray diffraction pattern has shown that the samples have ZnSe, SnSe, Se, and Sn phases.

Synthesis of Fe:ZnSe nanopowders via the co‐precipitation method for processing transparent ceramics

AbstractFe:ZnSe nanopowders were synthesized via the co‐precipitation method for fabricating transparent ceramics. FexZn1−xSe (0.00 ≤ x ≤ 0.06) powders that were calcined at 400°C yielded a single‐phased cubic ZnSe, but when the calcination temperature was raised to 500‐600°C, ZnO phase was created. Introduction of pressure could avoid appearance of ZnO. XRD Scherrer analysis revealed a monotonic increase in lattice parameter with increasing Fe2+ content. The average powder particle size increased with calcination temperature from several nanometers at 80°C to hundreds of nanometers at 600°C. Attempts to pressurelessly sinter ZnSe powders resulted in the partial decomposition of ZnSe, thus spark plasma sintering was employed to sinter Fe0.01Zn0.99Se transparent ceramics with pure ZnSe phase composition, which could be well sintered at 950°C for 30 minutes under an applied pressure of 60 MPa. SEM observations of the polished and thermally etched microstructure of the ceramic revealed a dense microstructure with average grain size of approximately 35 μm, and a few micropores were observed at the grain boundaries. The transparent ceramic exhibited good transmittance in the mid‐far infrared range, with the highest transmittance 57% at 12 μm. This paper confirmed the scheme of synthesis of Fe:ZnSe nanopowders by liquid‐phase co‐precipitation method for sintering transparent ceramics.

Preparation of ZnSe powder by vapor reaction during combustion synthesis

Abstract ZnSe powders have been prepared by vapor reaction during combustion synthesis. The powders contain both cubic and hexagonal ZnSe, where the fraction of the hexagonal phase increases with increasing distance from the evaporation source. The powders consist of spherical particles and rod-like crystals with sizes from submicron to a few microns. In UV–Vis region, the ZnSe powders have two absorption edges at 450–500 nm and 650–700 nm, likely connected with intrinsic band-gap transition and defect energy levels. From the optical absorption data, the band-gap of the ZnSe powders is estimated to be 2.4–2.5 eV. Under an UV or blue excitation, the ZnSe powders show very weak near-band-edge emission but strong defect-induced red emission. It appears that the ZnSe powders synthesized by vapor reaction clearly differ from the bulk ZnSe sample by melt solidification in both phase composition and optical properties.