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Structural and photoluminescence investigations of Cr3+ mixed Li2O—Bi2O3—ZrO2—SiO2 glass ceramics for optoelectronic device application
摘要： Chromium oxide mixed Li2O―Bi2O3―ZrO2―SiO2 (Cr3+:LBZS) glasses were crystallized by heat treatment. Structural (X-ray di?raction, surface morphology, energy dispersion, DTA, FT-IR and Raman) and spectroscopic (optical absorption and luminescence), of these Cr3+:LBZS glass ceramics were studied. XRD pattern of Cr3+: LBZS glass ceramic samples exhibited distinct crystalline peaks. SEM images of the Cr3+: LBZS glass ceramic materials have revealed well identi?ed and distributed crystals of reformed size. The glass transition (Tg) and various crystallization temperatures (Tc1), (Tc2) and (Tc3) of these ceramics were identi?ed by DTA analysis. The shift in the wavenumbers of di?erent symmetrical and asymmetrical band positions of these glass ceramics were analysed by FT-IR and Raman studies. The optical bandgap (Eo), CFSE (Dq) and nephelauxetic ratio (β) were calculated. Photoluminescence properties were also investigated.
关键词： Luminescence,FTIR,DTA,Structure,Cr3+: LBZS glass ceramics,Optical
更新于2025-09-23 15:23:52
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Simultaneous realization of broad temperature stability range and outstanding dielectric performance in (Ag+, Ta5+) co–doped TiO2 ceramics
摘要： Effects of sintering condition on dielectric properties and microstructure were systematically investigated in (Ag1/4Ta3/4)0.005Ti0.995O2 ceramics. A giant dielectric constant of ~9831 (1 kHz) and a relatively low dielectric loss of ~0.041 (1 kHz) were realized at the optimal sintering condition of 1330 °C with a holding time for 10 h. Notably, stable temperature coefficient (within -6.8% to 8.8%) of the dielectric constant at 10 kHz was achieved in a broader temperature range (-200–200 °C), which shows superior temperature stability of our sample than the application requirements (-55~200 °C and ?εr/ε25 °C < ±15%) of commercial X9R capacitor.
关键词： sintering conditions,dielectric properties,ceramics,temperature stability
更新于2025-09-23 15:23:52
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PVDF composites with spherical polymer-derived SiCN ceramic particles have significantly enhanced low-frequency dielectric constants
摘要： We report a novel functional hybrid film fabricated by using polysilazane-derived SiCN ceramics as fillers and polyvinylidene fluoride (PVDF) as the matrix. Regular spherical-shaped and amorphous SiCN ceramic powders were fabricated via a facile solvothermal method combined with a polymer-derived ceramic (PDC) process. The dielectric properties of the SiCN/PVDF composites were investigated by broadband dielectric spectroscopy from 0.1 Hz to 106 Hz. The composites showed significantly enhanced low-frequency dielectric constants. When the SiCN loading content reached 40 vol%, the dielectric constant of the composites was approximately 360 at 0.1 Hz, which is 20 times the value of pure PVDF (18). The dielectric constant of the composites at 0.1 Hz fit the effective medium theory (EMT) model well. The results suggest that the SiCN/PVDF composites are promising dielectric materials and have potential use in electrical applications.
关键词： spherical SiCN ceramics,SiCN/PVDF composite,high-e
更新于2025-09-23 15:23:52
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Synthesis of Eu2O3 doped BaO-TiO2-GeO2 based glass-ceramics: Crystallization kinetics, optical and electrical properties
摘要： Eu3+ doped transparent glass-ceramics (GCs) containing non-centrosymmetric ferroelastic Ba2TiGe2O8 (BTG) crystals as the major crystalline phase have been synthesized. BTG crystal phase was generated in the glass matrix with mole percent composition 30BaO-15TiO2-55GeO2 synthesized by melt quenching technique followed by controlled crystallization through ceramming heat-treatment. A di?usion controlled surface crystallization event with zero and constant nucleation rates was determined through a comparative study of some linear and nonlinear solid state reaction models. Nonlinear crystallization kinetics studies facilitated determination of the experimental ceramization temperature and time for fabrication of transparent glass-ceramics containing BTG nanocrystals. XRD, FTIR, TEM and FESEM measurements con?rmed the dispersion of BTG nanocrystals of size 20–100 nm in the glass matrix. Local crystal environment around Eu3+ ions facilitated the enhancement of photoluminescence of glass-ceramics with respect to the precursor glass. High dielectric constant, low loss and dissipation factors were observed for the GCs.
关键词： Refractive index,Glass-ceramics,Photoluminescence,Dielectric properties,Crystallization kinetics,Hysteresis loop
更新于2025-09-23 15:23:52
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Effect of indirect restorative material and thickness on light transmission at different wavelengths
摘要： Purpose: The aim of this study was to evaluate the influence of indirect restorative material type and thickness on the transmission of different wavelengths from a broad-banded dental curing light. Methods: Four dental indirect restorative materials for computer-aided design and computer-aided manufacturing (CAD/CAM) were evaluated: [RC] resin/ceramic hybrid material (Lava Ultimate), [FC] feldspathic ceramic (VitaBlocs), and two zirconia-based ceramics ([ZK] Katana; and [ZL] Lava). Total loss of irradiance (TL) was measured for blue (WB, 425–490 nm) and violet (WV, 350–425 nm) wavelengths. Specimens of 15 mm with varying thicknesses (0.5, 1.0, 1.5, and 2.0 mm) were fabricated (n = 5). A plasma-arc dental light-curing unit was used (Arc Light-II). To assess TL as a function of wavelength, a software (Spectra Suite v5.1) connected to a spectroradiometer (USB2000) and an integrating sphere (CTSM-LSM-60-SF) was used. Data was subjected to statistical analysis (two-way ANOVA and post-hoc Tukey test, α = 0.05). Results: A 0.5 mm interposition resulted in TL from 50.5 to 67.2%, depending on material. Increased thickness resulted in higher TL for all materials. FC showed less TL compared to ZK. In general, WV showed higher TL than did WB, and WV/WB proportion decreased with increasing thickness. Conclusions: Indirect materials significantly reduced TL, and this effect is greater with increasing thickness. WV showed lower penetration compared to WB.
关键词： Ceramics,Photopolymerization,Irradiance,Composite,Zirconia
更新于2025-09-23 15:23:52
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Electric field-induced toughening in GaN piezoelectric semiconductor ceramics
摘要： In this paper, the effect of an applied electric field on fracture toughness of polarized GaN piezoelectric semiconductor ceramics was studied by using experimental and numerical methods. The results show that fracture toughness increases by 22% under a field intensity of 0.83 kV cm?1, and with further increase of the electrical filed, fracture toughness remains unchanged. This is completely different from the fracture characteristics of traditional piezoelectric ceramics that is thought to decrease with an applied electric field. The reason for such a difference is attributed to the redistribution of free electrons. It is expected that this finding will be instructive to the reliability design of piezoelectric semiconductor structures and devices.
关键词： GaN,Electric field,Fracture toughness,Piezoelectric semiconductor ceramics,Toughening
更新于2025-09-23 15:23:52
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Excellent photoluminescence and temperature sensing properties in Ho3+/Yb3+ codoped (Y0.88La0.09Zr0.03)2O3 transparent ceramics
摘要： Ho3+/Yb3+ codoped (Y0.88La0.09Zr0.03)2O3 transparent ceramics were prepared by a high temperature solid-state reaction method. SEM observation confirms that there are no obvious impurities or pores existed in the grain boundaries of the samples. Accordingly, all the samples show excellent transparency in the visible and near-infrared range. Upon 980 nm excitation, strong green emission peaked at 549 nm, red emissions centered at 667 and 756 nm, as well as near infrared emission located at 2 μm respectively from Ho3+ ions are observed. By utilizing the fluorescence intensity ratio (FIR) technique, the temperature sensing behaviors of the optimal sample (Yb0.03Ho0.01Y0.84La0.09Zr0.03)2O3 are investigated at different excitation power densities based on the non-thermally coupled levels of 5F4/5S2 and 5F5. The thermometry is found to be immune to the excitation power density, leading to the consistent calibration curves and sensing sensitivities at the different power densities. The maximal sensing sensitivity is about 71.28×10?4 K?1 at 563 K. The results indicate that the Ho3+/Yb3+ codoped (Y0.88La0.09Zr0.03)2O3 transparent ceramics are promising for the temperature sensors, display devices and 2 μm solid-state lasers.
关键词： Upconversion luminescence,Rare earth,Optical thermometry,Transparent ceramics
更新于2025-09-23 15:23:52
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Pseudocubic-based polymorphic phase boundary structures and their effect on the piezoelectric properties of (Li,Na,K)(Nb,Sb)O3-SrZrO3 lead-free ceramics
摘要： CuO-added 0.96(LixNa0.5-xK0.5)(Nb1-ySby)O3-0.04SrZrO3 ceramics were sintered at 1020oC for 6 h. Various crystal structures were synthesized in these specimens by controlling the Li2CO3 (x) and Sb2O5 (y) contents: pseudocubic, orthorhombic-pseudocubic polymorphic phase boundary (PPB), tetragonal-pseudocubic PPB, orthorhombic-tetragonal-pseudocubic PPB, and orthorhombic-tetragonal PPB structures. The pseudocubic structure developed in these specimens was similar to the R3m rhombohedral structure instead of the Pm3m cubic structure because the specimens with a pure pseudocubic structure showed good ferroelectric and piezoelectric properties. The piezoelectric properties of the specimens were influenced by their crystal structures. The specimen with the tetragonal-pseudocubic PPB structure showed the best piezoelectric properties because this structure was similar to the tetragonal-rhombohedral morphotropic phase boundary structure developed in Pb(Zr1-xTix)O3-based ceramics. In particular, the specimen with the tetragonal-pseudocubic PPB structure corresponding to x = 0.05 and y = 0.065 showed the largest d33 and kp values of 431 pC/N and 0.43, respectively.
关键词： K)(Nb,Piezoelectric properties,Polymorphic phase boundary structure,Sb)O3-SrZrO3-based lead free piezoelectric ceramics,Pseudocubic structure,Na,(Li
更新于2025-09-23 15:23:52
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High room-temperature pyroelectric property in lead-free BNT-BZT ferroelectric ceramics for thermal energy harvesting
摘要： Pyroelectrics are attracting increasing attention because they enable pyroelectric generators to extract energy from low-gradient-temperature heat for portable electronic devices. High pyroelectric coefficient around room temperature is essential for high-performance energy harvesters, which, unfortunately, is only commonly achieved in lead-based ferroelectrics. Herein we report a high room temperature pyroelectric response of 27.2 × 10-4 C m-2 K-1 in 0.94(Bi0.5Na0.5)TiO3-0.06Ba(Ti0.75Zr0.25)O3 lead-free ceramics by modulating the Zr4+/Ti4+ ratio to tune the ferroelectric-relaxor antiferroelectric-like phase transition point to around ambient temperature, whose pyroelectric response is one order of magnitude higher than that of the sample without Zr and even comparable to those of lead-containing pyroelectrics. The theoretical analysis revealed that introduced Zr4+ could incorporate into the TiO6 octahedral lattices and break the long-range translational symmetry of BaTiO3 lattices, resulting in the reduction of B-site ion displacement activation energy and transition point of ferroelectric-relaxor antiferroelectric-like phase, giving rise to a pronounced room-temperature pyroelectric effect in BNT-BZT.
关键词： BNT-BZT ceramics,Energy harvesting,Room temperature pyroelectric property,Phase transition
更新于2025-09-23 15:23:52
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Preparation and Characterization of Na<sub>2</sub>O-Y<sub>2</sub>O<sub>3</sub>-P<sub>2</sub>O<sub>5</sub>-SiO<sub>2</sub> Transparent Glass Ceramics
摘要： Transparent glass ceramics containing Na3.6Y1.8(PO4)3 crystals were successfully synthesized using high temperature melting quenching and subsequent heat treatment of the precursor glass with a composition 15Na2CO3-3Y2O3-45SiO2-31H3BO3- 5.4P2O5-0.6Sb2O3 (mol%). The impact of heat treatment is investigated in detail. The glass sample was tested by differential scanning calorimetry analysis to determine the heat treatment system. The ideal heat-treated condition is at 650°C for 2 h. The structure and morphology properties were systematically analyzed by recording X-ray diffraction patterns and scanning electron microscopy images, which indicate that Na3.6Y1.8(PO4)3 crystal were precipitated homogeneously among the glass matrix. The microstructural of precursor glass and glass ceramic were compared by analyzing FTIR spectra, indicating the formation of phosphate groups in glass ceramic. The refractive index of glass ceramics samples were measured. In the visible region, the transmittance of glass ceramics is up to 85%. Moreover, the relationship between the refractive index of the sample and the transmittance is discussed.
关键词： Na3.6Y1.8(PO4)3,glass ceramics,preparation,transparent
更新于2025-09-23 15:23:52