As-quenched Glass Research Articles

Effects of electropulsing on the glass transition and structural relaxation of a Cu60Zr28Ti12 metallic glass

The effects of electric pulsing current treatment on the glass transition and crystallization of a Cu60Zr28Ti12 metallic glass have been studied. It has been found that after electropulsing treatment the onset glass transition temperature Tg, the onset crystallization temperature Tx, and the first crystallization peak temperature Tp of the Cu60Zr28Ti12 glassy alloy are reduced, while supercooled liquid range ΔT is almost unchanged. It indicates that the glass transition and crystallization of the Cu60Zr28Ti12 glassy alloy are promoted by electropulsing treatment. The Vicker’s hardness of electropulsed Cu60Zr28Ti12 glassy alloy is about 870kg/mm2, much higher than those of the as-quenched glass and sub-Tg isothermally annealed glassy alloys. The results show that the effect of pulsing current on structural relaxation is much stronger than that resulted by isothermal annealing. It suggests that treating the glassy alloys with pulsing current is a possible way to optimize the properties of metallic glasses.

Structural and optical properties of (100−x)(Li2B4O7)−x(SrO–Bi2O3–0.7Nb2O5–0.3V2O5) glasses and glass nanocrystal composites

Glasses of various compositions in the system $(100-x)({Li_2B_4O_7})-x(SrO-Bi_2O_3-0.7Nb_2O_5-0.3V_2O_5})$ $(10\leq x \leq 60$, in molar ratio) were prepared by splat quenching technique. The glassy nature of the as-quenched samples was established by differential thermal analyses (DTA). The amorphous nature of the as-quenched glasses and crystallinity of glass nanocrystal composites were confirmed by X-ray powder diffraction studies. Glass composites comprising strontium bismuth niobate doped with vanadium $(SrBi_2(Nb_{0.7}V_{0.3})_2O{_9{_-_\delta}$ (SBVN)) nanocrystallites were obtained by controlled heat-treatment of the as-quenched glasses at 783 K for 6 h. High resolution transmission electron microscopy (HRTEM) of the glass nanocrystal composites (heat-treated at 783 K/6 h) confirm the presence of rod shaped crystallites of SBVN embedded in ${Li_2B_4O_7}$ glass matrix. The optical transmission spectra of these glasses and glass nanocrystal composites of various compositions were recorded in the wavelength range 190–900 nm. Various optical parameters such as optical band gap $(E_{opt})$, Urbach energy $(\Delta E)$, refractive index (n), optical dielectric constant $(\epsilon ^{\prime}_\infty)$ and ratio of carrier concentration to the effective mass $(N/m ^\ast)$ were determined. The effects of composition of the glasses and glass nanocrystal composites on these parameters were studied.

Temperature effects on luminescence properties of Cr3+ ions in alkali gallium silicate nanostructured media

We have investigated the optical properties of Cr3+ ions in an alkali gallium silicate glass system and in two glass-based nanocomposites with nucleated β-Ga2O3 nanocrystals. The nucleation and growth of the nanocrystalline phase in the host glass matrix were monitored by Raman scattering spectroscopy and angle-dispersive x-ray diffraction. A broadband luminescence, associated with the T24-A24 transition from the weak crystal field of octahedral Cr3+ sites, dominated the emission of the precursor as-quenched glass. The luminescence spectra of the synthesized glass-ceramic nanocomposites revealed a crystal-like E2-A24 strong emission and indicated that the major fraction of Cr3+ ions was located within the nanocrystalline environment. The variable-temperature studies of the nanocomposites demonstrated that the fluorescence of Cr3+ ions can be transformed from sharp R lines of the E2-A24 transition to a combination of R lines and of the broad band of the T24-A24 transition. We propose a simple distribution model where the major part of Cr3+ ions is located in the nanocrystalline phase of the glass-ceramic composites in the octahedral environment, substituting the gallium atoms in the β-Ga2O3 crystal structure. The developed nanocrystalline glass-ceramics are a promising class of Cr3+-doped oxide glass-based optically active composite materials.

Preparation and characterization of dielectric glass-ceramics in Na 2O–PbO–Nb 2O 5–SiO 2 system

Glass-ceramics in the Na 2O–PbO–Nb 2O 5–SiO 2 system have been synthesized to produce bulk materials with nanometer-sized crystals grown in a glass phase via roll-quenching followed by controlled crystallization. X-ray diffraction studies indicate that Pb 2Nb 2O 7, NaNbO 3 and PbNb 2O 6 phases are formed from the as-quenched glass in temperature range from 750 to 900 °C. Pb 2Nb 2O 7 crystallizes at 750 °C and disappears at 850 °C, NaNbO 3 is the primary phase at 850 °C, while PbNb 2O 6 is formed at a higher temperature of 900 °C. The dielectric properties of the glass-ceramics formed through controlled crystallization have a strong dependence on the phase assemblages that are developed during heat treatment. The highest dielectric constants (> 600) were found in samples annealed at 850 °C for 3 h. Microstructural observation shows that randomly oriented, nanometer-sized crystalline are found with residual glass concentrated at crystallite boundaries. Further studies by scanning tunneling electron microscopy (STEM) in conjunction with energy dispersive spectroscopy (EDS) reveals inhomogeneous distribution of NaNbO 3 and PbNb 2O 6 in the sample annealed at 850 °C for 3 h and these phases contribute to the high dielectric constant.

Crystallization kinetics and dielectric properties of nanocrystalline lead strontium barium niobates

The crystallization kinetics and phase developments of PbO–BaO–SrO–Nb2O5–B2O3–SiO2-based glass-ceramics was investigated. Lead strontium barium niobate, (Pb,Sr,Ba)Nb2O6, with a tetragonal tungsten-bronze structure formed as the major crystalline phase, which showed evidence of both surface and bulk crystallization. The results of the present study showed significant evidence of a change in crystallization mechanism between the as-heated surface and the interior of glass-ceramics. This effect could be attributed to a volatilization of PbO taken place readily on the surface region of sample during heating. The grain size of the bulk-nucleated (Pb,Sr,Ba)Nb2O6 crystals was substantially smaller than that of surface-nucleated crystals. This result facilitated meeting the capacitors as high energy density application due to the ultrafine grains (<60 nm) obtained. The dielectric constant increased from 27 for the as-quenched glass to 200 for a highly crystallized glass-ceramic, which was attributed to a significant volume fraction of (Pb, Sr, Ba) Nb2 O6 phase.

The structure of ZrO2phases and devitrification processes in a Ca–Zr–Si–O-based glass ceramic: a combined a-XRD and XAS study

The structure of the Zr atomic environment in a CaO–ZrO2–SiO2glass ceramic as a function of thermal treatments has been studied, combining X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD) and anomalous XRD (a-XRD) techniques. The analysis of XRD patterns demonstrates that the devitrification process proceeds through the partial segregation of Zr-depleted phases (wollastonite-like) and Zr-rich phases (Zr oxides). The XAS and a-XRD measurements at the ZrK-edge have been exploited in order to obtain a closer insight into the atomic structure around the Zr atoms. In the as-quenched glass the Zr atom is sixfold coordinated to O atoms in an amorphous environment rich in Ca and Si. Thermal treatment firstly (T= 1273–1323 K) causes partial segregation of Zr in the form of an oxide with a tetragonal zirconia (t-ZrO2) crystalline structure. Raising the temperature (T= 1373 K) causes the formation of ZrO2crystallites in the monoclinic crystallographic phase (baddeleyite, m-ZrO2). Analysis of the XAS data shows that a considerable amount of Zr remains in an amorphous calcium silicate phase.

Characterization of free volume changes associated with shear band formation in Zr- and Cu-based bulk metallic glasses

The free volume model for flow in metallic glasses predicts a significant increase in free volume at the onset of plastic deformation. The details of these structural changes are unclear, however, particularly during strain localization in shear bands. In this study, the free volume changes associated with inhomogeneous plastic deformation of a Cu-based bulk metallic glass were examined using positron annihilation spectroscopy (PAS). PAS results indicated that there was a distribution of free volume site sizes in both the as-quenched and rolled glasses, and that the concentration of larger sites increased with deformation. Differential scanning calorimetry was also used to observe the glass transition behaviors of Cu- and Zr-based glasses after rolling and annealing. Annealing resulted in an increase in the height of the endothermic glass transition peak, consistent with structural relaxation relative to the as-quenched material. Deformation resulted in both a lower endothermic peak height and an earlier and deeper exothermic peak associated with structural relaxation, indicating a more disordered structure with more free volume.

Nucleation Behavior of Li2O-Na2O-SiO2 Glass Doped with Platinum

Nucleation behavior of 0.5L2O•0.5Na2O•2SiO2 glass doped with 0.005 mass% platinum as a nucleating agent was studied. Differential thermal analysis (DTA) showed that no exothermic peak due to crystallization appeared in the as-quenched bulk glass with Pt addition, but that a crystallization peak appeared in the glass with Pt addition, which was heat-treated at lower temperature previously. A number of crystal particles were observed in the interior of the glass with Pt addition after two stage heat-treatments. The crystal particles had a needle-like shape. General needle-like crystals and abnormal ones were observed, the latter of which is dendrite of fiber-like shape. The crystalline phase, precipitated in the glass, was identified as Li2O•SiO2 by X-ray diffraction (XRD) measurement. The growth rate of the Li2O•SiO2 crystals was determined with an optical microscope, and was found to increase steadily with rising temperature in the range 580-680°C.

Investigation of Bone Formation using Non-Crystalline Calcium Phosphate Glass in Beagle Dogs

Investigation of Bone Formation using Non-Crystalline Calcium Phosphate Glass in Beagle Dogs

An investigation of amorphous phase separation, leachability and surface area of an ionomer glass system and a sodium-boro-silicate glass system

Glasses from a complex SiO2-Al2O3-P2O5-CaO-CaF2 glass series, known as 'ionomer glasses' were investigated. For comparison, a sodium-boro-silicate (s-b-s) glass system, which is known to undergo amorphous phase separation was also investigated. Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDX) and BET surface area and pore distribution analysis were the principal analytical techniques used in this study. SEM analysis of the ionomer glass compositions revealed smooth spherical droplets of 2–15 nm while the background morphology appeared rough and speckled. A classic interconnected structure was observed for the s-b-s glass. EDX analysis of the s-b-s glass confirmed that the sodium-borate phase was removed by leaching with 0.3 M HNO3, leaving behind a silica-rich structure. EDX analysis of ionomer glasses leached with 10% NaOH showed that the calcium and phosphate phases were being removed, although not to completion. For the base s-b-s glass a surface area of m 82 g−1 was recorded. However, the base glass after extraction with 0.3 M HNO3 of the sodium borate rich phase gave a BET surface area of 330 m2 g−1 indicating that it had already undergone phase separation on quenching from the melt, giving rise to a fine scale interconnected structure. The leached s-b-s glasses exhibited type 4 adsorption/desorption isotherms characteristic of mesoporous materials. Glasses which had been heat treated at 580°C for 4 h exhibited a surface area of 62 m2 g−1. This indicates that the as-quenched glass is already phase separated and that the phase separated microstructure is coarsening on heat treatment. A surface area of 4 m2 g−1 was measured for the base ionomer glasses. After leaching with 10% NaOH this value rose 10-fold with a maximum surface area of 44.1 m2 g−1 being recorded. The ionomer glasses also exhibited adsorption/desorption isotherms characteristic of mesoporous materials.

Medium-Range Order and Crystallization in Zr59Cu20Al10Ni8Ti3 and Zr57Cu20Al10Ni8Ti5 Metallic Glasses Investigated by NMR

ABSTRACTMedium-range order and quasicrystal formation in Zr57Cu20Al10Ni8Ti5 and Zr59Cu20Al10Ni8Ti3 metallic glasses are investigated by means of nuclear magnetic resonance (NMR). The samples are prepared by rapid solidification and annealed to induce primary quasicrystal formation. 27Al and 63Cu NMR spectra and spin relaxation curves are recorded before and after the annealing process. The spectral width of 27Al and 63Cu NMR spectra is relatively small and can be taken as a proof for the presence of medium-range order in these metallic glasses. By simulations of 27Al and 63Cu NMR second moments in various binary Al and Cu compounds the medium-range orders L12 AlZr3 and C11b CuZr2 can be identified in both as-quenched metallic glasses. After heat treatment both metallic glasses show considerable changes in the 63Cu NMR second moments, whereas the 27Al NMR second moments show only relatively small changes. Furthermore, the 63Cu NMR second moment after heat treatment in Zr57Cu20Al10Ni8Ti5 is about half as large as in Zr59Cu20Al10Ni8Ti3 indicating different types of crystallization during heat treatment.

Synthesis and characterization of cerium-doped glasses and in vitro evaluation of bioactivity

The results of preparation, characterization and in vitro bioactivity evaluation of phosphosilicate glasses based on Bioglass ® 45S5 (SiO 2 45; Na 2O 24.5; CaO 24.5; P 2O 5 6 wt%) doped during melting with (1.5–13.5 wt%) cerium dioxide (CeO 2), has been reported. The choice of cerium was related to its low toxicity associated with bacteriostatic properties; cerium-doped bioactive glasses could be useful when implantation concerns local infected areas. The maximum value that permitted forming a homogeneous glass was 13.5 wt% and enabled us to get a better insight into CeO 2 effect on the chemical behaviour of glasses. The as-quenched glasses were characterized by means of magnetic and spectroscopic measurements that revealed the prevailing presence of cerium (III). The bioactivity of the glasses was tested by soaking them in a simulated body fluid at 37 °C, under continuous stirring. ICP measurements were carried out for ion concentration determinations and the solution/glass interface was investigated by scanning electron microscopy equipped with energy dispersive analyzer (SEM/EDS technique) to check morphological modifications; the solids were investigated by means of X-ray powder diffraction and IR techniques. The results indicated that at low cerium content the glass degradation and repolymerization gave rise to an internal silicon-based layer and an external calcium-phosphate-based layer formed on the glass surface; high cerium content retards the glass degradation and gave rise to cerium–phosphate layer instead of calcium one. The cerium was never found in solution. For the reacted glasses, in the external layer, at 10% and 13.5% CeO 2 contents the molar ratio Ca/P were ≈1 and 0.8 respectively and the molar ratio Ce/P was ≈0.3 in both cases. On the surface of the glasses with the highest cerium content it could distinguish new regular aggregates mainly formed by cerium and phosphate (Ce/P≈3.5, Ca/P≈0.6). In the cerium-free glass and with low cerium content (1.5 wt%) the calculated Ca/P ratio was 1.67, as calculated for pure hydroxyapatite. At low cerium content (BG-1.5 Ce) the glass behaviour was strictly similar to that of Bioglass ® 45S5.

Low‐temperature crystallization of MgSiO3 glasses under electron irradiation: Possible implications for silicate dust evolution in circumstellar environments

Abstract— Synthetic MgSiO3 glasses were irradiated at room temperature by 300 keV electrons in a transmission electron microscope (TEM). One of the samples had been previously irradiated by 50 keV He+ ions. Electron irradiation induces the nucleation and growth of randomly oriented nanometer‐sized crystallites. The crystallites first consist of MgO and subsequently of forsterite (Mg2SiO4). Both are seen to form within an amorphous SiO2 matrix. The rate of crystallization of the samples has been monitored by conventional TEM imaging and electron diffraction. The sample that had been pre‐irradiated with He+ ions is found to transform faster than the as‐quenched glass. The crystallization of metastable MgSiO3 glasses is explained by ionizing radiation‐induced elemental diffusion that allows the reorganization of matter into a more favourable thermodynamic state. These results show that ionizing radiation interactions could account for crystal formation as observed in infrared spectroscopy in some young stellar environments.

Effects of annealing at high pressure on structure and mechanical properties of Al87Ni7Gd6 metallic glass

The effects of annealing and annealing with a superimposed pressure of 940 MPa on the primary crystallization behaviour of α-Al and the resulting micro-hardness have been studied for as-quenched Al87Ni7Gd6 metallic glass. Isothermal annealing experiments were conducted for 30 min at 188 °C, 191 °C, and 205 °C in silicone oil maintained either at atmospheric pressure (i.e. 0.1 MPa) or at 940 MPa. XRD analyses detected the evolution of structure with annealing at 0.1 MPa, while specimens annealed with 940 MPa pressure exhibited sharper diffraction peaks than those annealed at 0.1 MPa. DSC measurements were conducted on the as-received amorphous ribbons as well as ribbons annealed at different temperatures at either 0.1. MPa or with 940 MPa superimposed pressure. Specimens annealed with 940 MPa pressure exhibited higher onset temperatures (i.e. Tx1) and temperatures for the first exothermic peak (i.e. Tp1) for primary crystallization. TEM measurements revealed an increase in the volume fraction of α-Al with increases in annealing temperature, while micro-hardness measurements revealed an increase in hardness with increasing amounts of α-Al. Specimens annealed with 940 MPa pressure exhibited further increases in both the volume fraction of α-Al and resulting micro-hardness.

Lithium borate–strontium bismuth tantalate glass nanocomposite: a novel material for nonlinear optic and ferroelectric applications

Glass nanocomposites in the system (100 − x)Li2B4O7–xSrBi2Ta2O9 (0 ≤ x ≤ 22.5, in molar ratio) were fabricated via a melt quenching technique followed by controlled heat-treatment. The as-quenched samples were confirmed to be glassy and amorphous by differential thermal analysis (DTA) and X-ray powder diffraction (XRD) techniques, respectively. The phase formation and crystallite size of the heat-treated samples (glass nanocomposites) were monitored by XRD and transmission electron microscopy (TEM). The relative permittivities (er′) of the glass nanocomposites for different compositions were found to lie in between that of the parent host glass (Li2B4O7) and strontium bismuth tantalate (SBT) ceramic in the frequency range 100 Hz–40 MHz at 300 K, whereas the dielectric loss (D) of the glass nanocomposite was less than that of both the parent phases. Among the various dielectric models employed to predict the effective relative permittivity of the glass nanocomposite, the one obtained using the Maxwell’s model was in good agreement with the experimentally observed value. Impedance analysis was employed to rationalize the electrical behavior of the glasses and glass nanocomposites. The pyroelectric response of the glasses and glass nanocomposites was monitored as a function of temperature and the pyroelectric coefficient for glass and glass nanocomposite (x = 20) at 300 K were 27 µC m−2 K−1 and 53 µC m−2 K−1, respectively. The ferroelectric behavior of these glass nanocomposites was established by P vs. E hysteresis loop studies. The remnant polarization (Pr) of the glass nanocomposite increases with increase in SBT content. The coercive field (Ec) and Pr for the glass nanocomposite (x = 20) were 727 V cm−1 and 0.527 µC cm−2, respectively. The optical transmission properties of these glass nanocomposites were found to be composition dependent. The refractive index (n = 1.722), optical polarizability (αm = 1.266 × 1023 cm3) and third-order nonlinear optical susceptibility (χ(3) = 3.046 × 10−21 cm3) of the glass nanocomposite (x = 15) were larger than those of the as-quenched glass. Second harmonic generation (SHG) was observed in transparent glass nanocomposites and the deff for the glass nanocomposite (x = 20) was found to be 0.373 pm V−1.

Pyroelectric, Ferroelectric and Optical Properties of Glass Nanocomposite: Lithium Borate--Bismuth Tungstate

Glass nanocomposites in the system (1 m x ) Li 2 B 4 O 7 m x Bi 2 WO 6 (0 h x h 0.35, in molar ratio) were fabricated by splat quenching technique. The as-quenched samples were X-ray amorphous. Differential Thermal Analyses (DTA) confirmed their glassy nature. The composites on heat-treatment at 720 K yielded monophasic crystalline bismuth tungstate in lithium borate glass matrix. The average size and the spherical nature of the dispersed crystallites were assessed via High Resolution Transmission Electron Microscopy (HRTEM). The dielectric constants ( l r ) of both the as-quenched and post heat-treated composites were found to increase with increase in x (bismuth tungstate content) at all the frequencies (100 Hz-40 MHz) in the temperature range 300 K-870 K. While the dielectric loss ( D ) decreased with increasing x . The pyroelectric coefficients of the as-quenched (consisting 20 nm sized crystallites) and 720 K heat-treated sample ( x = 0.3) were determined as a function of temperature (300 K-873 K) and the values obtained at room temperature were 20 and 60 w C/m 2 K respectively. The as-quenched and heat-treated (720 K) glass nanocomposites exhibited ferroelectric (P Vs E) hysteresis loops. The remnant polarization and coercive field of the heat-treated glass nanocomposite at 300 K were respectively 2.597 w C/cm 2 and 543 V/cm. These glass nanocomposites were birefringent in the 300-873 K temperature range.

Nanocrystallization of SrBi 2Nb 2O 9 from glasses in the system Li 2B 4O 7SrOBi 2O 3Nb 2O 5

Transparent glasses in the system (100− x)Li 2B 4O 7– x(SrOBi 2O 3Nb 2O 5) (10≤ x≤60) (in molar ratio) were fabricated by a conventional melt-quenching technique. Amorphous and glassy characteristics of the as-quenched samples were established via X-ray powder diffraction (XRD) and differential thermal analyses (DTA) respectively. Glass–ceramics embedded with strontium bismuth niobate, SrBi 2Nb 2O 9 (SBN) nanocrystals were produced by heat-treating the as-quenched glasses at temperatures higher than 500 °C. Perovskite SBN phase formation through an intermediate fluorite phase in the glass matrix was confirmed by XRD and transmission electron microscopy (TEM). Infrared and Raman spectroscopic studies corroborate the observation of fluorite phase formation. The dielectric constant ( ε r) and the loss factor ( D) for the lithium borate, Li 2B 4O 7 (LBO) glass comprising randomly oriented SBN nanocrystals were determined and compared with those predicted based on the various dielectric mixture rule formalism. The dielectric constant was found to increase with increasing SBN content in LBO glass matrix.

A Kinetic Analysis on Non-Isothermal Glass-Crystal Transformation in Glassy Semiconductors. Application to the Sb0.16As0.29Se0.55 Alloy

In the present work, a kinetic analysis on glass-crystal transformation from differential scanning calorimetry (DSC) data under non-isothermal condition is described. A method has been developed for analyzing the evolution with time of the volume fraction crystallized and for calculating the kinetic parameters at non-isothermal reactions in materials involving formation and growth of nuclei. Considering the assumptions of extended volume and random nucleation, a general expression of the fraction crystallized has been obtained, as a function of the temperature in bulk crystallization. The kinetic parameters have been deduced, assuming that the crystal growth rate has an Arrhenius-type temperature dependence, and the nucleation frequency is either constant or negligible. The theoretical procedure described has been applied to the crystallization kinetics of glassy alloy Sb0.16As0.29Se0.55 with and without previous reheating. According to the study carried out, the n-values have been found: 3.1 for the as-quenched glass and 2.1 for the reheated glass. As n decreases with reheating, it is possible to state that the annealing causes the appearance of new nuclei. The phases at which the alloy crystallizes after the thermal process have been identified by x-ray diffraction. The diffractogram of the transformed material suggests the presence of microcrystallites of Sb2Se3 and AsSe remaining in a residual amorphous matrix.

Dielectric anomaly in strontium borate–bismuth vanadate glass nanocomposite

Transparent glass nanocomposites in the pseudo binary system (100− x) SrB 4O 7 (SBO)– x Bi 2VO 5.5 (BiV) (0≤ x≤70) were prepared by the splat quenching technique. The nano-crystallization of bismuth vanadate (BiV) in 50 SBO–50 BiV (in mol%) glass composite has been demonstrated. These were characterized for their structural, thermal and dielectric properties. As-quenched composites under study have been confirmed to be amorphous by X-ray powder diffraction (XRD) studies. The glass transition temperature ( T g) and crystallization temperatures ( T cr) were determined using differential thermal analyses (DTA). High resolution transmission electron microscopic (HRTEM) studies carried out on heat-treated samples reveal the presence of spherical nanosize crystallites of Bi 2VO 5.5 (BiV) dispersed in the glassy matrix of SrB 4O 7 (SBO). The dielectric constant (ϵ r) and the dielectric loss ( D) measurements were carried out on the as-quenched and heat-treated glass nanocomposite samples in the frequency range 100 Hz–10 MHz. The as-quenched and the heat-treated at two different temperatures (720 and 820 K) samples exhibited broad dielectric anomalies in the vicinity of the ferroelectric-to-paraelectric transition temperature of the parent BiV ceramics. The Curie–Weiss law was found to be valid at a temperature above the transition temperature, establishing the diffused nature of the transition.

Structural Relaxation of Pd39Ni10Cu30P21Bulk Metallic Glass Under High Pressure

The Pd39Ni10Cu30P21 bulk metallic glass isisothermally relaxed under various pressures. The degree of thestructural relaxation is evaluated in terms of the enthalpyrecovery behaviours involved in the irreversible glass transitionprocesses by using a temperature-modulated differential scanningcalorimetry technique. A roughly linear increase of the recoveryenthalpy is observed within the experimental pressure rangefrom 2.67 to 4.45 GPa, which reflects the release of the frozen-inenthalpy in the as-quenched glass with increasing relaxation pressure.The pressure dependence of the timescale of the enthalpy recoveryprocesses is also exhibited.