Hruby Parameter Research Articles

Transport property mechanism of semiconducting x MgO:(50-x) PbO:50V2O5 glasses

ABSTRACT The electrical properties of semiconducting Oxide glasses with composition x MgO(50-x) PbO:50V2O5 glasses have been investigated. The glasses were prepared by the normal melt quenching technique. The X-ray diffractograms of the present glass system show that the prepared glass samples are perfectly amorphous. The DSC patterns indicate that the MgO-substituted glass samples behave like the eutectic composition up to x = 15 mol%. The DC conductivity is measured in the temperature range of 300 to 500 K, and data are fitted with Mott’s and Schnakenberg models. The conductivity of all the glass compositions increases with increasing MgO content. The conduction mechanism of these glasses was non-adiabatic. The various parameters, such as activation energy, average site separation between transition metal ions and polaron radius, have been calculated and found consistent with Mott’s small polaron hopping non-adiabatically between different sites. The Hruby parameter (kg) for this glass system has been calculated and discussed.

Influence of Sb doping on thermal properties and electrical conductivity mechanism of SbxSe50–xSn20Te30 chalcogenide glassy systems

Tunability of thermal, and electrical characteristics of SbxSe50-xSn20Te30 (x = 2, 4, 6, and 8 at. %) bulk glass systems with varying doping concentrations are the major objective of this study. The melt quenching technique has been employed to synthesize the samples. Various thermal parameters have been inspected by using DSC measurements. The effect of Sb addition on the glass transition temperature (Tg), crystallization temperature (Tc), peak crystallization temperature (Tp), and melting temperature (Tm) have been observed from DSC thermograms. The dependence of Tg, Tc, Tp, and Tm on the heating rate has been measured. The thermal analysis is performed under non-isothermal conditions at heating rates of 5, 10, 15, and 20 K/min. The activation energies for the glass transition temperature are estimated by using the Kissinger method and are found to decrease from (211.21-168.85) KJ.mol−1. Thermal stability and glass forming ability for all glassy compositions have been examined in terms of Hruby's parameter. In addition, electrical conductivity mechanisms over vast temperature and frequency ranges are analyzed. The DC conductivity mechanism has been analyzed by deploying Mott and Greaves's variable range hopping model, while the AC conductivity mechanism has been analyzed by deploying the modified correlated barrier hopping model. AC conductivity scaling property has been examined by using the Pan and Ghosh model. The influence of Sb addition has been observed as the DC and AC conductivity increases with the increase of doping concentration.

Thermal Stability of ZnO/Tm<sub>2</sub>O<sub>3</sub> Substitution on Tellurite-Zinc-Bismuth-Sodium (TZBN) Glasses

Tm2O3 doped tellurite-zinc-bismuth-sodium (TZBN) glass samples with varying compositions were prepared through melt quenching technique. The composition of these glass was 60 TeO2 - (30-x) ZnO - 5 Bi2O3 - 5 Na2O - x Tm2O3 with (x = 0.5; 1.0; 1.5; 2.0 and 2.5 mol%). We reported the result of a systematic study of the thermal properties of these glass by using differential thermal analysis (DTA). The thermal characteristics of these glass (glass transition, Tg, crystallization, Tc, and melting, Tm) increased significantly with Tm2O3 content and the glasses were more thermally stable (greater ΔT=Tc-Tg). The glass transition value slightly increased from 314 to 323 °C otherwise thermal stability ΔT changed from 112 to 131°C. The ratio of Tg/Tm values for TZBN doped Thulium glasses were about 0.558 to 0.589, indicated that these glasses possess good thermal stability. The Hruby parameter (Kg) with Tm3+ doped in this study improved glass-forming ability, which is desirable for various applications such as optical fibers drawing and sensors.

Physical, thermal, optical, shielding and elastic properties of Bi2O3–B2O3–TeO2 glass system doped with Fe2O3

For the present study, Bi2O3–B2O3–TeO2 glass system is doped with Fe2O3 to determine its effect on the various properties of the system. Six samples of compositions 35 Bi2O3-40 B2O3-(25-x) TeO2-x Fe2O3 mol %, where x = (0, 0.1, 0.5, 1, 1.5, 2 mol %), are prepared via the melt quenching technique and their physical, thermal, optical, radiation shielding and elastic properties investigated. Raman spectra reveals that the glass network is comprised of BO3, BO4, TeO4 and BiO6 structural units which are disrupted by Fe, acting as a network modifier. XRD patterns confirmed the amorphous nature of the samples. EPR spectra reveal that dopant iron is present in Fe3+ state, at various spins, in the glass network system. Optical absorption measurements (UV-VIS) show that increasing Fe2O3 concentration decreases optical band gap energies which in turn increase refractive index, polarizability and optical basicity of the samples. Metallization criterion indicates that the synthesized glass system non-metallic nature slightly decreases with increasing dopant concentration. Bandgap energy decreased with doping, indicating a decrease in the disorder in the glass network system. Decreases in density and cross-link density were observed with doping whilst increases in molar volume, oxygen molar volume and oxygen packing density occurred. An increase in Hruby's parameter indicates that the thermal stability and glass-forming ability of the samples increased with doping. Elastic moduli increased with doping, increasing the stiffness and damage resistance of the samples. Doping causes a slight decrease in radiation shielding ability; however, radiation shielding ability remains greater than that of concrete.

Enhancement of optical properties and dielectric nature of Sm3+doped Na2O–ZnO–TeO2Glass materials

Samarium doped Na2O–ZnO–TeO2 (NZT) glasses were prepared by the melt quenching method. The glass-forming ability and glass stability of prepared glass was estimated by Hruby parameter using Differential Thermal Analysis (DTA) and Thermo-gravimetric Analysis (TGA). The study of FTIR spectra and X-ray diffraction described the ionic nature and the amorphous pattern of glass respectively. The absorption peaks were observed for the transitions 6H5/2-4P3/2 at 402 nm, 6H5/2-4M19/2 at 418 nm, 6H5/2-4I15/2 at 462 nm and 6H5/2-4I11/2 at 478 nm in the absorption spectra. The optical band gap energy (Eg) was calculated and observed to be decreased from 2.95 eV to 1.58 eV with doping concentration. The visible emission band was observed in the Sm3+ doped glass samples. The variation of dielectric constant with frequency was found to be independent for the frequency range 3 kHz - 2 MHz. The measurement of temperature-dependent dc conductivity showed Arrhenius type mechanism of conduction.

Thermal, structural and optical behaviour of Eu3+ ions in Zinc Alumino Boro-Silicate glasses for bright red emissions

In present work we report the thermal, structural and optical behaviour of 20SiO2-(20-x) B2O3–10Al2O3–10ZnO–30NaF–10ZnF2-xEu2O3 glass system where Eu2O3 ions is doped in different molar concentrations (x = 0.1, 0.5, 1.0, 1.5, 2.0 and 2.5 mol %). The Differential thermal analysis measurement was employed to study the thermal stability of the glasses through various thermal parameters such as Dietzel factor (ΔT), Hruby's parameter (KH), Weinberg Parameter (KW) and Lu and Liu Parameter (KLL). FTIR studies exhibit the presence of BO3, BO4, SiO2 vibrational units and the deconvoluted peak areas is used for the calculation of bridging and non-bridging oxygens. From the absorption spectra, the indirect bandgap energy (Eg) and Urbach's energy (EU) of the glasses have been calculated. Judd-Ofelt (JO) intensity parameters (Ω2 and Ω6) have been evaluated from the emission spectrum. The radiative parameters such as radiative transition probability (AR), branching ratio (βR), stimulated emission cross-section (σse) and radiative lifetimes (τR) were obtained using the JO parameters for the transitions 5D0→7F1,2,4 of Eu3+ ions. The decay life time of the 5D0 level is found to be single-exponential for all the Eu3+ doped glasses. An increase in lifetime values for the prepared glasses was found with increase in Eu3+ concentration from 0.1 mol% to 2.0 mol%. The colour chromaticity values and CCT values show the bright red emission from the prepared glasses.

Physical and thermal properties of gold nanoparticles embedded Nd3+- doped borophosphate glasses: Spectroscopic parameters

A series of glass with appropriate chemical compositions (48-x) B2O3–30P2O5–20ZnO–2Nd2O3-xAu, (0 = x ≤ 2.5 mol%) were prepared by using the melt quenching technique. The glass phase structure was confirmed with the aid of the X-ray diffraction (XRD) technique. The thermal characteristics of the prepared glass were approved by using the differential thermal analysis (DTA) technique. The highest thermal stability 196.8 °C were detected for the BPZNA4 sample, the glass tendency explained by calculating the Hruby's parameter (H), the maximum value of H parameter was detected for sample BPZNA4 with 1.984, this clearly shows the highest ability to form a glass. The optical properties were studied by using ultraviolet visible near infrared (UV–Vis–NIR) spectroscopy and the emission transitions studied by using photoluminescence spectroscopy (PL). The absorption spectra for the samples doped with Nd3+ ions show nine transitions, the photoluminescence spectra exhibited two emission transitions for green and red light emission due to tetrahedral symmetry and octahedral symmetry, respectively. The decay curves of Nd3+ ions were calculated for all the glass samples. It was shown that the lifetimes dependent on the concentration of Au NPs and the glass composition.

Characterization, bioactivity and antimicrobial properties of a metal-ceramic composite for bone regeneration

The present work aims to develop biocompatible composites for bone regeneration. Four metal-ceramic composites 20Ag, 10Cu, 20Cu and 10Ag10Cu were fabricated, in which Ag, Cu was added to a glass-ceramic (35SiO2-35.4CaO–24Na2O-5.6P2O5). Wollastonite-2M (CaSiO3) was the major phase identified in all samples. The two composites 20Cu and 10Ag10Cu showed more thermally stabilized behaviour, and glass stability measured by two glass parameters Hruby parameter (KH) and Weinberg parameter (KW) was also improved with Ag and Cu addition. The in vitro bioactivity test showed that formation of apatite layer was initiated after 9 days of immersion in simulated body fluid (SBF) for 20Cu and 10Ag10Cu composites. All composites showed antibacterial activity against p. Aeruginosa bacteria, which is considered to be a common cause of post-surgical infections. It was found that 10Ag10Cu composite showed better antibacterial activity as compared to other samples. Hence, sample 20Cu and 10Ag10Cu showed the most optimum bioactive and antibacterial properties, which makes them suitable for reconstruction and regeneration of damaged bones.

Thermal Stability and Hardness Studies of Ge Doped Se–Te Glassy Alloys

The amorphous glassy alloys Se82 – xTe18Gex (x = 0, 4, 8, 12, at %) was synthesized using melt quench technique. Thermal stability was examined with the help of various parameters such as Dietzal parameter, Hruby parameter, Saad and Poulin and Lu and Liu parameters. Vicker hardness was obtained from Vicker hardness tester and other related thermo-mechanical properties such as volume of micro-voids, energy formation of micro-voids and modulus of elasticity were calculated.

Impact of La2O3/Y2O3 ratio on crystallization kinetics of CaO based alumino-borosilicate glasses and compatibility with Crofer and 8YSZ for SOFCs

In the present investigation, the novel glass series xLa2O3-(10-x)Y2O3-15SrO-15CaO-10B2O3-10Al2O3-40SiO2 (x = 2, 4, 6, 8) has been synthesized by melt quenching technique. The characteristic glass temperatures and the inflection point temperature (Tf) for the glasses have been determined by DTA and differential DTA (DDTA), respectively. The activation energy is calculated using Kissinger, Moynihan and Augis and Benett models. Various kinetic parameters such as fluctuation free volume (fg), Hruby parameter (Hr), bulk thermal expansion coefficient (αf) and k parameters are calculated for studying glass stability with varying La2O3/Y2O3 ratio. The amorphous nature and crystalline phase formation has been studied by X-ray diffraction. Furthermore, the coefficient of thermal expansion (CTE) for all the glasses has been calculated. The interaction studies of the diffusion couples of glasses with pre-oxidized Crofer 22APU and 8YSZ have been carried out at 850 °C. 2 LaY glass is very stable and promising potential sealant for the SOFCs.

ESR and FT-IR Studies on GeO2 Substituted Lead Vanadate Semiconducting Glass System

A series of Germania-lead-vanadium pentoxide glasses with x=5, 10 and 15 mol% were prepared by melt quenching technique and they were characterized by X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Fourier Transform Infrared (FT-IR) and Electron Spin Resonance (ESR) techniques. X-ray diffraction results reveal that all samples are perfect amorphous in nature. Differential scanning calorimetry results indicate that the substituent GeO2 is replacing PbO in the glass network in such a way that the eutectic composition is maintained. The Fourier Transform Infrared spectra characterized V=O stretching frequency around 968 cm-1 upto 15 mole% and interestingly the Electron Spin Resonance studies did not yield well resolved hyperfine structure due to exchange broadening which varyies with nature of dopant. The Hruby parameter (Kg) for this glass system has been evaluated and reported.

Crystallisation kinetics and thermal stability analysis of Se82-xTe15Sn3Sbx (0≤x≤6) glassy alloys

This paper reports the results of study of crystallization kinetics and thermal stability in Se82-xTe15Sn3Sbx (0 ≤ x ≤ 6) glassy alloys. The alloys were analysed using DTA (differential thermal analysis) technique under non-isothermal conditions at heating rates of 5, 10, 15, 20 K/min, Activation energy of glass transition has been evaluated using Kissinger and Moynihan methods while Matusita, Kissinger and Augis and Bennett approaches has been employed to study the crystallization mechanism. Thermal stability and glass forming ability for all compositions has been analysed in terms of reduced glass transition temperature and Hruby's parameter.

Influence of Sb substitution on thermal and electrical characteristics of Ge-Sn-Se chalcogenide glass system

Present research work reports the systematic investigation of thermal and electrical characterizations of Ge20Sn10Se70-xSbx (x = 0, 3, 6, 9, 12, 15) glass system to probe the structural modifications. Bulk samples are prepared using melt quenching technique. Differential scanning calorimetric technique (DSC) is used at the constant heating rate of 100C under nonisothermal conditions. Different kinetic parameters viz. glass transition temperature Tg, Hruby parameter Hr, crystallization temperature Tc, etc., have been calculated. Glasses under study shows good thermal stability, hence, can find practical applications especially in optical fiber technology. Further, in the current study, an attempt has been made to observe the variation in conductivity with respect to the increase in temperature for amorphous Ge20Sn10Se70-xSbx (x = 0, 3, 6, 9, 12, 15) using two probe method and hence the band structure and corresponding conduction mechanism is studied.

Thermal analysis of cadmium addition on the glass transition and crystallization kinetics of Se–Te–Sn glassy network

Calorimetric measurements have been performed in quaternary glassy system Se78−xTe20Sn2Cdx (x = 0, 2, 4, and 6) to study the thermally induced glass transition and crystallization phenomena. The characteristics kinetic temperatures (glass transition temperature $$T_{\text{g}}$$ , onset crystallization temperature $$T_{\text{o}}$$ , peak crystallization temperature $$T_{\text{c}}$$ ) and static melting temperature $$T_{\text{m}}$$ of the quaternary glassy series have been determined using their non-isothermal DSC curves. These temperatures were utilized to calculate the thermal stability $$S$$ and the Hruby parameter $$H_{\text{R}}$$ for the studied glasses. Both the activation energy of glass transition $$E_{\text{t}}$$ and the activation energy of crystallization $$E_{\text{c}}$$ for all compositions were evaluated using the well-known Kissinger's relation and the method of Augis–Bennett. Values of the fragility index $$m$$ and the crystallization rate factor $$K_{\text{p}}$$ were estimated using the activation energy values $$E_{\text{t}}$$ and $$E_{\text{c}}$$ , respectively. The compositional dependence of the above-mentioned parameters was discussed on the basis of rigidity models and according to the formation of iono-covalent bonds when our glassy Se–Te–Sn system is doped with a heavy element as Cd.

A Study of Thermal Stability And Crystallization Kinetics of SbSeGe Glassy Alloys

Alloys of Sb10Se90-xGex (x = 0, 19, 21, 23, 25, 27) have been prepared using melt quenching technique. Differential thermal analysis has been used to determine the three characteristic temperatures, glass transition (Tg ), glass crystallization (Tc ) and melting temperature (Tm ), at four heating rates 5, 10, 15 and 20 K/min. The thermal stability and ease of glass formation have been evaluated in terms of Hruby parameter and reduced glass transition temperature respectively. The activation energy for glass crystallization (Ec ) has been calculated using Kissinger's method and Marseglia theory. The composition dependence of Tg and Ec has also been discussed.

Influence of CaO/MgO ratio on the crystallization kinetics and interfacial compatibility with crofer 22APU and YSZ of strontium based alumino-borosilicate glasses for SOFC applications

High temperature hermetic sealants are required for the stability and good efficiency of the solid oxide fuel cells (SOFCs). Glass and glass ceramics are promising sealant materials due to their desirable properties and flexible compositions. In the present study, the novel glass series (10 + x) CaO-(10 − x) MgO-10SrO-10B2O3-20Al2O3-40SiO2 (x = 0, 2.5, 5, 7.5) has been synthesized via melt quenching route. These glass/glass ceramics are characterized by X-ray diffraction to evaluate the amorphous nature and phase formation, respectively. The activation energy has been analyzed by using three different theoretical models – Kissinger Model, Moynihan Model and Augis and Benett Model. In addition to this, the characteristic glass temperatures and coefficient of thermal expansion (CTE) have been obtained from DTA, differential DTA (DDTA) and Dilatometry. Various stability parameters like Hruby parameter, Saad Parameter, fluctuation free volume (fg) and bulk thermal expansion coefficient (αf) are also calculated with varying CaO/MgO ratio (R). Furthermore, to analyze the stability of the glasses with varying CaO/MgO ratio over a broader range of temperature, k parameters i.e. kb (T) and kf (T) are also evaluated for different heating rates. The diffusion couples of glasses with pre oxidized Crofer 22APU and YSZ fabricated at 850 °C for 500 h have been characterized using scanning electron microscopy (SEM) and X-ray dot mapping to investigate the sealing characteristics with varying CaO/MgO ratio. The glass series 15 CaMg is very stable and promises to be a good sealant for solid oxide fuel cells.

Synthesis, characterization of CaF2 doped silicate glass-ceramics

This paper reports the fabrication and characterization of silicate glass–ceramics doped with (0–12mol%) CaF2. TGA-DSC analysis was carried out to determine the crystallization temperature and stability of glass measured by two glass parameters; Hruby parameter KH=(Tx−Tg)/(TL−Tx) and Weinberg parameter KW=(Tc−Tg)/TL. It was found that with CaF2 doping improved sinterability at low temperature and provided stability to the glass. The XRD pattern exhibits a single phase of combeite and doping of CaF2 cause increase in crystallite size. Microstructure of samples was also improved with CaF2 addition, pores were significantly reduced. After 15days immersion in simulated body fluid all samples developed apatite layer onto its surface. Hence, the addition of CaF2 provided bioactive glass-ceramic material having a low processing temperature.

Physical, thermal, structural and optical properties of Dy3+ doped lithium alumino-borate glasses for bright W-LED

Rare earth (RE) doped glasses have potential applications due to their emission efficiencies of 4f–4f and 4f–5d electronic transitions. Among all the rare earths, Dy3+ doped glasses have drawn much interest among the researchers for their intense emission in the visible region from 470 to 500nm and around 570 to 600nm. The physical, thermal, structural and optical properties of Dy3+ doped lithium alumino-borate glasses (LABD glasses) have been studied for white LED (W-LED) application. The glasses were synthesized by conventional melt quench technique. X-ray diffraction spectra revealed the amorphous nature of the glass sample. An FTIR spectrum was carried out to study the glass structure and various functional groups present in the LABD glasses. Optical absorption spectra were recorded by UV–vis-NIR spectrometer. Allowed direct and indirect band gaps were obtained by Tauc's plot. Thermal parameters like glass thermal stability (∆T), Hruby's parameter (Kgl), etc. were calculated by DTA graph. Photoluminescence excitation and emission spectra's were measured at room temperature. The emission spectra shows two intense emission bands at around 482nm (blue) and 574nm (yellow) corresponds to the 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions respectively along with one feeble band at 662nm (red) corresponds to 4F9/2→6H11/2 transition. The CIE chromaticity co-ordinates were calculated for all glass samples. CIE chromaticity diagram shows glass LABD-4 containing 0.5mol% Dy2O3 with colour co-ordinates X = 0.34 and Y = 0.38 have highest emission intensity. These glasses having emission in the white region and thus can be used for bright white LED.

Prominent spectral features of Sm3+ ion in disordered zinc tellurite glass

Trivalent rare earth doped glasses with modified spectroscopic features are essential for solid state lasers and diverse photonic applications. Glass composition optimisation may fulfil such demand. Stimulating the spectral properties of samarium (Sm3+) ions in tellurite glass host with desired enhancement is the key issue. Glasses with composition (80−x)TeO2–20ZnO–(x)Sm2O3, where 0⩽x⩽1.5mol% are prepared using melt quenching method. The role of varying Sm3+ contents to improving the absorption and emission properties of the prepared glasses are determined. XRD pattern verifies amorphous nature of synthesised glasses. FTIR spectroscopy has been used to observe the structural modification of (TeO4) trigonal bipyramid structural units. DTA traces display prominent transition peaks for glass transition, crystallisation and melting temperature. Samples are discerned to be stable with desired Hruby parameter and superior glass forming ability. The UV–Vis–NIR absorption spectra reveals nine peaks centred at 470, 548, 947, 1085, 1238, 1385, 1492, 1550 and 1589nm. These bands arise due to 6H5/2→4I11/2, 4G5/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2 and 6F1/2 transitions, respectively. The direct, indirect band gap and Urbach energy calculated from the absorption edge of UV–Vis–NIR spectra are found to appear within (2.75–3.18)eV, (3.22–3.40)eV, and (0.20–0.31)eV, respectively. The observed increase in refractive index from 2.45 to 2.47 is ascribed to the generation of non-bridging oxygen atoms via the conversion of TeO4 into TeO3 units. Conversely the decrease in refractive index to 2.39 is attributed to the lower ionic radii (1.079Å) of Sm3+. PL spectra under the excitation of 452nm display four emission bands centred at 563, 600, 644 and 705nm corresponding to 4G5/2→6H5/2, 6H7/2, 6H9/2 and 6H11/2 transitions of samarium ions. Excellent features of the results nominate these compositions towards prospective applications.

Structure and thermal analysis of Se100 − x(SbSn)x chalcogenide glasses

Se100−x(Sb0.5Sn0.5)x (3≤x≤12at.%) glassy alloys were prepared using the melt quenching technique. The amorphous nature of the as-prepared samples was confirmed by scanning electron microscope (SEM) and X-ray diffraction (XRD) and the effect of the addition of Sb0.5Sn0.5 content on the glass transition and crystallization kinetics of amorphous Se has been studied. The glass transition temperature (Tg) was increased with increasing content of Sb0.5Sn0.5. This behaviour was discussed in terms of glass density (ρ), cohesive energy (CE) and the overall mean bond energy <E>. The values of the activation energy of crystallization were increased with increasing Sb0.5Sn0.5 content that was confirmed by increasing the Hruby's parameter (Krg) with the increase of Sb0.5Sn0.5 content. Furthermore, the difference between Tc and Tg was increased due to the delay in nucleation process. This leads to the enhancement of the thermal stability and consequently the glass forming ability.