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This study reports on the synthesis of tellurium-based glasses that have a wide transmission far beyond the second atmospheric window. Several far-infrared(IR) transmitting glass systems including Ge-In-Te, Ge-Ga-Te, as well as some compositions containing alkali halides (KI, CsI) or metal halides (PbI2, CuI, AgI, CdI2 or ZnI2) are reported. Their glass-forming ability, thermal stability, and IR transmitting property are investigated. The results show that the broad absorption peak in the 15-20 μm disappear in the Fourier-transform infrared (spectrometer) spectra when gallium is replaced by indium. Te-based chalcogenide glasses containing metal-halides show superior glass-forming ability and better thermal stability than those containing alkali halides. Among these glasses, the ΔT of glass composition 65GeTe4-17In2Te6-18AgI can be as great as 115 °C. In ternary system, the glass composition Ge16Te69(AgI)15 (ΔT = 120 °C) is stable enough toward crystallization in combination with broad transmission region and good chemical durability to be drawn into optical fibers. [ABSTRACT FROM AUTHOR]

The glass‐ceramics of AgI‐based electroconductive chalcogenide system was realized using an appropriate heat treatment at a fairly high temperature (Tg + 40°C) and different times ranging from 4 to 20 hours. The crystallization behavior and electroconductive properties of the heat‐treated samples were studied in detail. Transmission study was performed, and the results show that the cut‐off edge of the short wavelength is red‐shifted at prolonged annealing time but remains an excellent transmittance in the mid‐infrared (IR) region. XRD and scanning electron microscopy results indicated that the precipitated crystalline phases are mainly β‐/γ‐AgI. Moreover, a small amount of α‐AgI, which rarely existed at room temperature, is precipitated in the AgI‐rich chalcogenide glass‐ceramics. The ionic conductivity of all glass‐ceramics was enhanced by heat treatment in contrast to that of base glass. Raman analysis exhibited the structure variation in the glass sample after heat treatments. This study provided an observation of crystallization in chalcogenide glass containing large amounts of AgI and be of good guidance to fabricate novel AgI‐based chalcogenide glass‐ceramics that can be candidates in infrared optics and solid electrolyte applications. [ABSTRACT FROM AUTHOR]

As 2 Se 3 glass fibers measuring 250 μm in diameter were fabricated based on different draw processing parameters, including preform dropping temperatures (T 1 = T g + ΔT, ΔT = 20, 30, 40, 50 °C), fiber-drawing temperatures (T 2 = T g + ΔT, ΔT = 10, 20, 50 °C), and drawing speeds. Raman spectra indicated crystallization on fiber surface at high temperatures. After fiber drawing, oxygen was detected on fiber surface by energy dispersive X-ray spectra. High-quality fiber with minimum loss of 1.88 dB/m (at 9.05 µm) was achieved under optimal dropping temperature of 218.1 °C (T g + 30 °C), fiber-drawing temperature of 208.1 °C (T g + 20 °C), and drawing speed of 0.10 m/min. [ABSTRACT FROM AUTHOR]

In this paper, the effect of Sb2Se on the phase change characteristics of Ge2Sb2Te5 (GST) is systemically studied for applications in phase-change random access memory (PRAM). The crystallization temperature of Sb2Se–GST increases with increasing Sb2Se content, while the archival life of the amorphous state first decreases and then increases. The phase transition from face-centered-cubic (FCC) to hexagonal (HEX) is suppressed when the Se atomic percentage is higher than 9% for Sb2Se–GST films. The wide band gap and high value of B1/2 lead to a contrast in resistance of about five orders of magnitude between the amorphous and crystalline states. Compared with GST, Ge4Sb52Te9Se35 shows a high crystallization temperature, a wider band gap and a fast switching speed, suggesting it is a potential candidate for PRAM. [ABSTRACT FROM AUTHOR]

The crystallization characteristic, electrical, and optical properties of ZnSb-doped SbTe thin films have been systematically investigated. The results show that the crystalline phase, grain size, and the preferred orientation are influenced by ZnSb addition. Meanwhile, ZnSb doping can effectively increase the thermal stability of SbTe films such as crystallization temperature and crystallization activation energy, and maintain fast crystallization speed. Among ZnSb-doped SbTe films, ZnSbTe film exhibits both shorter complete crystallization time (135 ns at 70 mW) and appropriate thermal stability (keeping the amorphous state at 107.2 °C for 10 years). [ABSTRACT FROM AUTHOR]

Glass-ceramics of PbS-doped 80 GeS2·20 Ga2 S3 were fabricated by heat treatments of base glasses at Tg+30°C for different durations. They exhibited improved mechanical properties such as hardness and resistance to crack propagation, and meanwhile retained their excellent infrared transmission. X-ray diffraction and Raman results indicated that Ga2 S3 and GeS2 crystals were precipitated inside glassy matrix. The crystallization kinetics of base glass was investigated using differential scanning calorimetry under nonisothermal conditions. Compared with the previous work concerning on 80 GeS2·20 Ga2 S3 glass, there exists some different features of crystallization behavior. Such variation is discussed and correlated with the network structure and crystallization kinetics in this glass system. [ABSTRACT FROM AUTHOR]

The crystallization behavior of the 70GeS-20InS-10CsI glass introduced with 2 mol% AgS system has been studied under non-isothermal condition. The beginning of transmission is shifted toward longer wavelength as a function of annealing temperature. Thermal properties were measured by the differential scanning calorimeter. From the heating rate dependence of crystallization temperature, the activation energy ( E) for crystallization and the crystallization rate constant ( K) were calculated. The K value of 2.44 × 10 for the InS phase is about 28 times larger than the second CP, this is why the controllable crystallization to transparent chalcogenide glass-ceramics with sole InS crystallites can be achieved. By heat treatment with various temperatures, the hardness of the glass enhanced from 204 to 230.8 kg mm, while retained the transmittance of the 8-11 μm. [ABSTRACT FROM AUTHOR]

65GeS⋅25InS⋅10CsCl chalcohalide glass-ceramics containing β-InS crystallites in the glassy matrix were prepared by traditional melt-quenching and subsequent heat-treatment at a fairly low temperature ( T+10 C) for different durations. The transmission spectra show that the cut-off edge of short wavelength is red-shifted with the prolongation of annealing time, but remains an excellent transmittance in the mid-IR region. Meanwhile, its crystallization behavior was investigated systematically. The results show that the precipitation of β-InS crystal phase is responsible for the first crystallization peak, and the second crystal phase is GeS, which precipitated in the interior after a heat treatment at a high temperature ( T+70 C). Furthermore, the crystallization mechanism was investigated using the non-isothermal method. The crystallization rate constant K value of 6.08×10 s at 346 C for the β-InS phase is about three times larger than that of the GeS phase, indicating a much easier crystallization mechanism of β-InS phase. Therefore, it is easy to control the precipitation of sole β-InS crystallite, and to avoid interference of the second crystal phase GeS. [ABSTRACT FROM AUTHOR]

Diagram of the phase transformation behavior of GeS2- Ga2 S3- CsI glasses is realized in this article and the structure-property dependence of the chalcogenide glasses is elucidated using differential scanning calorimetry and Raman spectroscopy. We observe the compositional threshold of crystallization behavior locates at x = 6-7 mol% in (100− x)(0.8 GeS2-0.2 Ga2 S3)- x CsI glasses, which is confirmed by the thermodynamic studies. Structural motifs are derived from the Raman result that [ Ge( Ga) S4], [ S2 GeI2], [ S3 GaI], and [ S3 Ga- GaS3] were identified to exist in this glass network. Combined with the information of structural threshold, local arrangement of these structural motifs is proposed to explain all the experimental observations, which provides a new way to understand the correlation between crystallization behavior and network structure in chalcogenide glasses. [ABSTRACT FROM AUTHOR]

Enhanced luminescence in rare-earth-doped chalcogenide glass-ceramics is of great interest for the potential integrated optoelectronic devices. However, fundamental mechanism on the enhancement of luminescence upon crystallization remains largely unknown. We report the fabrication and characterization of wide transmission chalcogenide glass and glass-ceramics based on the 25 GeS2·35 Ga2 S3·40 CsCl:0.3 Er glass composition, and discuss the mechanism of enhanced luminescence. By monitoring the 4 I9/2-4 I15/2 of Er3+ transition, up-conversion luminescence of 12 times higher was observed in glass-ceramics compared with that in base glass. Electron paramagnetic resonance (EPR) and Raman scattering spectroscopies were employed to obtain the information of selective environment of Er3+ ions and microstructural evolution with the crystallization progress. Both of them evidenced that the enhanced up-conversion luminescence was mainly related to the local environmental evolution from a mixed chlorine-sulfur coordination to a low phonon energy chlorine coordination in the residual glassy matrix of glass-ceramics. [ABSTRACT FROM AUTHOR]

Glass-ceramics of 80 GeS2·20 In2 S3 were fabricated by heat-treating the base glass at 402°C ( Tg + 30°C) for different durations. The glass-ceramics exhibited some improved mechanical properties such as hardness and resistance to crack propagation, and meanwhile remained an excellent infrared ( IR) transmission. The XRD and Raman results showed that only In2 S3 crystals were precipitated inside glassy matrix. The evolution of two crystallization peaks ( CPs) in differential scanning calorimeter ( DSC) curves were studied with samples heat-treated at 402°C for different durations. It was found that the precipitation of In2 S3 crystal phase is responsible for the low-temperature (first) CP, whereas the high-temperature (second) CP shifts to a higher temperature with the elongation of the heat-treatment duration. The crystallization of the higher temperature phase was inhibited with the precipitation of In2 S3. Furthermore, crystallization mechanism was investigated using the nonisothermal method. The computed results showed that strictly more energy (higher activation energy, Ec) is essential for the precipitation of the higher temperature phase, which is in accordance with the DSC study of crystallized samples. More noticeable, the crystallization rate constant ( K) value of 6.639 × 10−8 s−1 for the second CP is ~ 5 orders of magnitude smaller than that of the In2 S3 phase, and this significant difference makes the crystallization of higher temperature crystal phase very hard. Consequently, controllable crystallization of 80 GeS2·20 In2 S3 chalcogenide glass-ceramics with sole In2 S3 crystallites can be achieved easily. [ABSTRACT FROM AUTHOR]

Transparent 90GeS⋅10GaS(G10) chalcogenide glass-ceramics containing β-GeS nanocrystals was successfully fabricated through controllable crystallization based on the knowledge of its nucleation-rate-like curve. Using the conventional Z-scan method, both large spectral dependence and crystallinity dependence of optical nonlinear parameters were learned under the excitation of different wavelengths that in proximity of the half-bandgap. In particular, a large value of figure of merit (FOM≈11.64) was obtained in the crystallized sample after the heat-treatment at 466°C for 40 h. Although it is not a straightforward process to select an appropriate medium for a specific application, this work opens a new way to construct suitable optical nonlinear properties (e.g., large FOM) though modifying the microstructure of chalcogenide glass-ceramics. [ABSTRACT FROM AUTHOR]

Femtosecond laser-induced crystallization and ablation of Ge2Sb2Te5 (GST) phase change film is investigated by reflectivity pump-probing technology. Below the ablation threshold, the face-centered cubic structure (FCC) state in the central area can be formed, and cylindrical rims are formed in the peripheral dewetting zone due to the solidification of transported matter. The time of surface temperature dropping to the crystallization point needs about 30 ps for 5.86 mJ/cm2 and 82 ps for 7.04 mJ/cm2, respectively. At higher laser fluence, crystallization GST island structures appear in the central ablation region due to the extremely short heating time (100 ps). Furthermore, crystallization rate is faster than the ablation rate of the GST film, which is caused by different reflectivity. [ABSTRACT FROM AUTHOR]

This study reports on the synthesis of tellurium-based chalcogenide films that have high thermal stability for phase change memory application. Several Te-based chalcogenide alloys of In-Bi-Te, Ag-Bi-Te, In-Sb-Te, Sn-Sb-Te, Zn-Ge-Te, and Ga-Ge-Te are reported. Their thermal, optical, and electrical properties are investigated. The results show that Bi-Te-based films have a higher crystallization temperature and greater activation energy compared with the other Sb-Te-based and Ge-Te-based films. Especially, In2.8Bi36.6Te60.6 film exhibits high crystallization temperature (252 °C) and great activation energy (5.16 eV), showing much improved amorphous thermal stability. A relatively wider optical band gap (0.674 eV) of thermal annealed In2.8Bi36.6Te60.6 film is obtained. In addition, it also has a higher amorphous/crystalline resistance ratio of about 105, implying that current consumption could be low in the phase-change memory operation. [ABSTRACT FROM AUTHOR]

Chalcogenide glasses are defined as a new category of non-crystalline solids on the basis of their characteristic covalent bonds and unique properties, such as broad infrared transmission window, low maximum phonon energy, high optical nonlinearity, semiconductivity, and photosensitivity. Inspired by the great successes that have been achieved in the development of oxide glass-ceramics, functionalized chalcogenide glass-ceramics have received intensive research attention. Moreover, the inherent properties of chalcogenide glasses have been explored and modified through controlled crystallization, to generate novel and unique features. This review aims to present a critical overview of the current state of the art in the controllable fabrication of functionalized chalcogenide glass-ceramics. The first section provides a brief introduction to chalcogenide glasses and glass-ceramics. The succeeding sections detail the fabrication strategies of chalcogenide glass-ceramics with various functions through different precipitated crystals and microstructures. This review provides a discussion of the mechanism that underlie the resultant properties of chalcogenide glass-ceramics. Furthermore, the crystallization mechanisms of chalcogenide glasses are discussed through the comparison of molecular-scale and nanoscale phase separation assisted crystallization mechanisms in oxide and oxyfluoride glasses. Finally, the remain section presents the key questions that remain unanswered, as well as provide perspectives on the future research trends. [ABSTRACT FROM AUTHOR]

The superior performance of Zn-doped Sb7Te3 films might be favorable for the application in phase change memory. It was found that Zn dopants were able to suppress phase separation and form single stable Sb2Te crystal grain, diminish the grain size, and enhance the amorphous thermal stability of Sb7Te3 film. Especially, Zn30.19(Sb7Te3)69.81 film has higher crystallization temperature (∼258 °C), larger crystallization activation energy (∼4.15 eV), better data retention (∼170.6 °C for 10 yr), wider band gap (∼0.73 eV), and higher crystalline resistance. The minimum times for crystallization of Zn30.19(Sb7Te3)69.81 were revealed to be as short as ∼10 ns at a given proper laser power of 70 mW. [ABSTRACT FROM AUTHOR]

Zn-doped Sb2Te films are proposed to present the feasibility for phase-change memory application. Zn atoms are found to significantly increase crystallization temperature of Znx(Sb2Te)1-x films and be almost linearly with the wide range of Zn-doping concentration from x = 0 to 29.67 at.%. Crystalline resistances are enhanced by Zn-doping, while keeping the large amorphous/crystalline resistance ratio almost constant at ∼105. Especially, the Zn26.07(Sb2Te)73.93 and Zn29.67(Sb2Te)70.33 films exhibit a larger resistance change, faster crystallization speed, and better thermal stability due to the formation of amorphous Zn-Sb and Zn-Te phases as well as uniform distribution of Sb2Te crystalline grains. [ABSTRACT FROM AUTHOR]

Abstract: Transparent glass ceramics based on Bi2O3–B2O3–TiO2 ternary glass system were prepared by controlled one-step heat treatment method. X-ray diffraction measurement confirms the formation of Bi2O3 phase crystals in glass network. Z-scan measurements at a wavelength of 750nm were employed to investigate the third-order optical nonlinearities of these transparent glass ceramics. The results show that the nonlinear properties were significantly enhanced after crystallization process. [ABSTRACT FROM AUTHOR]

The confinement of CsPbX 3 (X = Cl, Br, and I) perovskite nanocrystals (NCs) in a stabilized inorganic glass matrix is a new strategy for improving their long-term stability and promoting their applications in the optoelectronic field. Here, in situ nanocrystallization strategy is developed to precipitate CsPbBr 3− x I x NCs with arbitrary I/Br ratio among an elaborately designed GeS 2 –Sb 2 S 3 -based chalcogenide glass matrix. Spherical CsPbBr 3− x I x NCs are homogeneously distributed in the glass matrix after thermal treatment. The photoluminescence (PL) spectra show that the emission peaks of CsPbBr 3− x I x NCs can be tuned from 570 nm to 722 nm with the replacement of Br by I. The fs transient absorption (TA) spectra reveal that there exists some structural defects in the NCs, leading to short PL decay life. This work would shed light on confining CsPbX 3 NCs into glassy matrices, facilitating their future applications in photoelectronic fields. [ABSTRACT FROM AUTHOR]

Black α-phase CsPbI 3 of cubic perovskite structure receives intense attentions recently for its unique combination of high photoluminescence quantum yield, suitable bandgap, and long lifetime. However, α-CsPbI 3 presents poor chemical and thermodynamic stability under atmosphere condition. Here, we report a strategy for confining the α-CsPbI 3 perovskite into chalcogenide glassy matrix through controllable glass nanocrystallization. In the chalcogenide glass with an elaborately designed composition of 80GeS 2 ·16Sb 2 S 3 ·4CsPbI 3 , spherical α-CsPbI 3 nanocrystals were formed and observed clearly, which present good red photoluminescence centered at 701 nm. With the increasing heat-treated temperature, the size of α-CsPbI 3 nanospheres increases, while the crystal quantity decreases. It is found that the nanocrystallization of α-CsPbI 3 nanospheres in chalcogenide glass is controlled by Ostwald-ripening process. [ABSTRACT FROM AUTHOR]

Abstract Germanium-Telluride has been widely studied as a phase-change material due to its fast crystallization speed. The understanding of the crystallization kinetics is important to evaluate the potential applications of the material, but this is limited by the conventional calorimetry with low heating rate and narrow temperature range. We here employed an ultrafast calorimetry method, named flash differential scanning calorimetry, to investigate the crystallization kinetics of Ge x Te 100-x in a wide compositional range (15 ≤ x ≤ 55). By means of the X-ray diffraction, we found the complicated competition between crystalline GeTe and Te (or Ge) phases in these binary alloys. The crystallization kinetics of first crystalline phase were estimated and it was found that, Ge x Te 100-x generally has intermediate crystal growth speed and fragility, which is ascribed to the border between covalent and metallic properties. Component dependences of maximum crystal growth rate (U max) and fragility were investigated, revealing the component in x = 20.4 has the lowest U max of 1.22 × 10−3 m s−1 with the smallest fragility of 42.2, and the component in x ≈ 50 possesses the largest U max of 3.5 m s−1. It confirms that, GeTe is the most suitable phase-change material for information storage and GeTe 4 is the best media for information transparency in Ge-Te binary. Moreover, a tri-counter pattern was carried out for obtaining the crystal growth rate directly in studied supercooled Ge x Te 100-x liquids (15 ≤ x ≤ 55). In addition, we first found a peculiar component Ge 22 Te 78 with terrible thermal properties, i.e., phase separation, low crystallization temperature, ultrahigh fragility and anomalous crystallization kinetics. More importantly, together with the crystallization kinetics parameters of other glass formers, it was found a specific relation between reduced glass temperature (T rg) and U max for which can be benefit to simplify material screenings and performance optimizations. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

We have reported the fabrication and characterization of Ge 23.5 Ga 11.5 Se 65 glasses and glass-ceramics with different Er 3+ concentrations. It was found that, the emission properties of the bulk glasses showed the fluorescence intensity and lifetime increased until they reached a maximum, and then decreased with increasing Er 3+ concentration. This is due to concentration quenching effect although the maximum dissolving concentration of Er 3+ can be up to ∼1 wt% of Er. A careful thermal process has led to the formation of ∼80 nm β-Ga 2 Se 3 crystalline particles in Ge 23.5 Ga 11.5 Se 65 glasses doped with 0.8 wt% of Er 3+ . By monitoring 4 I 13/2 → 4 I 15/2 Er 3+ transition, almost fourfold enhancement in the intensity and ∼0.57 ms prolongation in the lifetime of near-infrared fluorescence at 1.54 μm have been observed after crystallization. It was assigned to the decreasing phonon energy of the local environment of Er 3+ ions during the crystallization. [ABSTRACT FROM AUTHOR]

In this paper, the effect of Zr on the phase change properties of Ge 2 Sb 2 Te 5 (GST) is systemically studied for phase-change random access memory. The sheet resistance ratio between amorphous and crystalline states achieves four to five orders of magnitude. The crystalline resistance, crystallization temperature ( T c ) and the 10 years data-retention of Zr-GST films increase with the Zr concentration. Zr-GST films are crystallized into a single phase without phase separation due to the Zr bonding with Sb and Te. With the increasing annealing temperature, the transformation from face-centered cubic (fcc) to hexagonal is suppressed when the Zr atomic content is higher than 6%, which is ascribed to the lack formation of the Te-Te pairs. The wide band gap of the amorphous Zr-GST films is favorable to reduce the threshold current. The incorporating Zr atoms are embedded in the inner atomic-scale structure of the GST, which contributes to performance improvement of the GST material for phase-change random access memory. [ABSTRACT FROM AUTHOR]

In this paper, the effect of Sb2Se on the phase change characteristics of Ge2Sb2Te5 (GST) is systemically studied for applications in phase-change random access memory (PRAM). The crystallization temperature of Sb2Se–GST increases with increasing Sb2Se content, while the archival life of the amorphous state first decreases and then increases. The phase transition from face-centered-cubic (FCC) to hexagonal (HEX) is suppressed when the Se atomic percentage is higher than 9% for Sb2Se–GST films. The wide band gap and high value of B1/2 lead to a contrast in resistance of about five orders of magnitude between the amorphous and crystalline states. Compared with GST, Ge4Sb52Te9Se35 shows a high crystallization temperature, a wider band gap and a fast switching speed, suggesting it is a potential candidate for PRAM. [ABSTRACT FROM AUTHOR]

The Zn-doped Sb 2 Te 3 films have been investigated systematically during the phase transformation process. It was found that, the increase of crystallization temperature in the Zn-doped Sb 2 Te 3 films leads to its enhanced amorphous stability, and Zn incorporation can increase electrical resistance, widen optical band gap and refine crystalline grain size. The crystallization mechanism can be tuned into nucleation-dominated from growth-dominated type. Moreover, Sb 2 Te 3 film with high Zn-doping concentration such as Zn 38.8 (Sb 2 Te 3 ) 61.2 film was found to exhibit a higher crystallization temperature (233 °C), better data retention ability (keeping the amorphous state at 146.5 °C for ten years), and wider band gap (0.839 eV). A lower threshold of crystallization (~ 25 ns) can be realized in the Zn 38.8 (Sb 2 Te 3 ) 61.2 film irradiated at the laser power of 70 mW in comparison with that in the conventional Ge 2 Sb 2 Te 5 film. We confirm that the Zn doping is responsible for a fast switching and the Zn 38.8 (Sb 2 Te 3 ) 61.2 compound is stable against segregation with cycling. [ABSTRACT FROM AUTHOR]

We prepared Mg-doped Sb 4 Te films and investigated their structural, electrical and optical properties. It was found that Mg could increase the crystallization temperature and improve the activation energy of crystallization as well as amorphous state stability of the Sb 4 Te film. Compared with Ge 2 Sb 2 Te 5 , the optimal composition of Mg 19.8 (Sb 4 Te) 80.2 exhibits a higher crystallization temperature (∼187 °C), and better data retention ability (keeping the amorphous state at 113.6 °C for ten years). Moreover, fast full crystallization (∼20 ns at a laser power of ∼60 mW) in the Mg 19.8 (Sb 4 Te) 80.2 film is confirmed, which is essential to achieve rapid data recording in phase change memory. [ABSTRACT FROM AUTHOR]

Highlights: [•] Phase change behavior of Sb-rich Ga–Sb–Se was studied for phase change memory. [•] Sb-rich Ga–Sb–Se films possess crystallization temperature higher than 225°C. [•] Sb-rich Ga–Sb–Se film has retention ability in excess of 135°C for 10years. [•] Compared with Ge2Sb2Te5, Ga10Sb60Se30 has fast crystallization speed. [ABSTRACT FROM AUTHOR]

Glass-ceramics containing Ga2S3 nano-crystals were reproducibly fabricated from the 45GeS2·30Ga2S3·25Sb2S3 chalcogenide glass by heat treatment at 335°C (Tg +30°C) for different durations. The obtained glass-ceramics are still transparent in the IR region and show improved thermal stability. Crystallization mechanism was investigated using the non-isothermal method. The results show that the crystallization rate constant K at 335°C for the Ga2S3 phase is about 2 orders of magnitude larger than that of the second crystallization peak in the DSC curve. So it is easy to control the crystallization process with only Ga2S3 crystallites precipitated. With the above advantages, it has a great potential for drawing infrared transmitting glass-ceramic fibers with improved mechanical properties and enhanced luminescence for application in optical amplifiers. [ABSTRACT FROM AUTHOR]

Highlights: [•] The amorphous Ge–Te–In films were prepared by magnetron co-sputtering method. [•] The Ge–Te–In film system has a high crystallization temperature. [•] Large redshift of the optical band gap is related to crystallization by annealing. [•] The structural rearrangements around Ge atoms occur during crystallization. [ABSTRACT FROM AUTHOR]

Abstract: Mg-doped Ge2Sb2Te5 (GST) films with different Mg doping concentrations have been prepared, and their crystallization behavior, structure and electrical properties have been systematically investigated for phase-change memory applications. The results show that the addition of Mg into GST films could result in an enhancement in crystallization temperature, activation energy and electrical resistance compared with the conventional GST films, indicating that a good amorphous thermal stability. On the other hand, the proper Mg concentration ranging from 13.6 to 31.1at.% can lead to a one-step crystallization process from amorphous to faced-centered cubic (fcc) phase and suppress the formation of the hexagonal close-packed (hcp) crystalline phase. X-ray photoelectron spectra (XPS) further confirm that the formation of covalent Mgcontribute to the enhanced thermal stability in Mg-doped GST films. [Copyright &y& Elsevier]

Abstract: The thermal and electrical properties of Zn1.25Sb2Te3 film have been investigated for phase change memory (PCM) applications. Compared with the conventional Ge2Sb2Te5, Zn1.25Sb2Te3 film exhibits a higher crystallization temperature (∼200°C), greater activation energy (2.71eV), and better data retention of 10 years at 105°C. In addition, higher crystalline resistance and better resistance contrast are helpful to reduce RESET current and achieve a higher On/OFF ratio of PCM, respectively. Raman spectra of crystalline thin films suggests that the local bonding arrangement around Sb atoms changes; Sb2Te3 component is thus mainly responsible for the phase transition in Zn1.25Sb2Te3 alloys. [Copyright &y& Elsevier]

Abstract: A systematic series of (Ge20Se15Te65)1− x –(SnI2) x (x =0, 0.05, 0.1, 0.15) chalcogenide glasses have been prepared. The amorphous nature can be confirmed by XRD and SEM. With the SnI2 content increasing, the indirect optical band gaps are decreased from 0.662 to 0.622eV according to Tauc laws. The introduction of SnI2 makes the glasses much easier to prepare and more stable against crystallization, making them drawable as optical fibers. The highest ΔT (130°C) value for (Ge20Se15Te65)0.9–(SnI2)0.1 glass composition can be obtained. A slight red-shifting of the long-wavelength cutting-off edge from 18.4 to 19.4μm was shown and it seems that SnI2 in these glasses offers the improvement in the far-infrared properties. [Copyright &y& Elsevier]

Abstract: Novel chalcogenide glasses based on GeS2–In2S3–Sb2S3 system were prepared by conventional melt-quenching method and their physicochemical properties, e.g. glass transition temperature, density, and Vickers micro-hardness, were studied in detail. The results show that the thermal, mechanical, and optical properties depend largely on four-coordinated Ge or In entities and are sensitive to the variation of the connectivity in the GeS2–In2S3–Sb2S3 glass network. It is a promising chalcogenide glass system suitable for rare earth doping or crystallization of rare earth doped crystals, which aims at optical applications of IR optical amplifier or efficient solid state laser. [Copyright &y& Elsevier]

Abstract: Dy3+ doped 40GeSe2–25Ga2Se3–35CsI (GGC) glass was synthesized, and optical spectrum, such as infrared transmission and Vis-Nir absorption was measured. Base on the Judd–Ofelt theory, the three Judd–Ofelt parameters Ω t (t =2, 4, 6) were calculated and the results were compared with other chalcogenide glasses. The small Ω 2 in GGC glass is ascribed to the weak covalency of Se–Dy bond. The theory of crystallization kinetics under non-isothermal condition was developed, and was applied to analyze this Dy3+ doped GGC glass. From the heating-rate dependence of crystallization temperature, the activation energy for crystallization E =148kJ/mol is obtained, and this value is much smaller than that of the undoped glass host, indicating the introduction of Dy3+ ions into the GGC glass will get the host crystallized easily. [Copyright &y& Elsevier]

Abstract: GeSe2–Ga2Se3–CsI chalcohalide glasses had been prepared by the melt-quenching technique. With the addition of CsI, the short wavelength cut-off edge of the glasses shifts to the short wavelength gradually, while the long wavelength cut-off edge located at ∼16μm is nearly unchanged. Thermal properties were measured by Differential Thermal Analysis (DTA). From the heating rate dependence of crystallization temperature, the activation energy for crystallization (E) and the order parameter (n) were calculated by the Kissinger equation. The results show that the activation energy of crystallization decreases dramatically with increasing of CsI content, and the most probable crystallization mechanism is volume controlled one-dimensional growth. [Copyright &y& Elsevier]

• Transparent chalcogenide glass-ceramic sample embedded CsCl nanocrystals of ~50 nm was obtained. • Phase separation with different droplet and interpenetrating structures were observed in chalcogenide glasses. • Raman spectra of these samples are almost unchanged with the increasing CsCl content. • The network structure of chalcogenide glasses retains acts as a solvent for the dissolution of CsCl. The effect of CsCl addition on the nanocrystallization and phase separation behaviors of (100 − x)(0.5GeS 2 – 0.5Sb 2 S 3) – x CsCl (x = 0, 5, 10, 15, 20, 25, 35 and 40 mol%) samples was investigated systematically by various characterization techniques. Transparent chalcogenide glass-ceramic sample embedded CsCl nanocrystals of ~50 nm was obtained successfully through one-step melt-quenching method in a glass with elaborated composition of 37.5GeS 2 ·37.5Sb 2 S 3 ·25CsCl, which is around the critical solubility of CsCl in GeS 2 – Sb 2 S 3 based glasses. With the further addition of CsCl (x > 25 mol%), phase separation with different droplet and interpenetrating structures were observed for the first time in chalcogenide glasses. The recognition of these phenomena would be of guiding significance for the future design and fabrication of chalcogenide glass-ceramics with specific microstructures and optical functionalities. [ABSTRACT FROM AUTHOR]

Novel chalcogenide glasses and glass-ceramics of (100-x)(0.5GeS 2 –0.5Sb 2 S 3)–xPbCl 2 (x = 0, 3, 5, 8, 10, 15, 20, and 25) were prepared by single-step melt-quenching technique, and their transmission spectra and thermo-mechanical properties are characterized. The solubility and spontaneous crystallization behavior of PbCl 2 are investigated by employing various techniques of XRD, SEM, and Raman spectra. Two-stage crystal growth was found in these samples with the increase of PbCl 2 content (x). The crystallization behavior of oversaturation and recrystallization of PbCl 2 in glasses is totally different from the typical nucleation and crystal growth initiated by thermal treatment. Especially, transparent chalcogenide glass-ceramic embedded PbCl 2 nanoparticles (~20 nm) was successfully fabricated when x reaches 10 mol%. This study is of guidance significance for future design and elaboration of optically functionalized chalcogenide glass-ceramics. • Novel GeS 2 –Sb 2 S 3 –PbCl 2 chalcogenide glasses and glass-ceramics were prepared. • The solubility and spontaneous crystallization behavior of PbCl 2 are investigated. • The variation of transmission spectra and thermo-mechanical properties is investigated with the increasing x. • Transparent chalcogenide glass-ceramic embedded PbCl 2 nanoparticles (~20 nm) was successfully fabricated. [ABSTRACT FROM AUTHOR]