Cure Characteristics,Mechanical and Thermal Properties of Al2O3 and ZnO Reinforced Silicone Rubber

The effects of alumina (Al₂O₃) and zinc oxide (ZnO) fillers on the curing characteristics, thermal and mechanical properties of silicone rubber were studied. Rheometer results indicate that the incorporation of ZnO fillers retards the curing process, whereas an enhancement in cure rate was observed for Al₂O₃. Higher maximum torque (M_H) and minimum torque (M_L) values was also observed for ZnO silicone rubber compounds compared to Al₂O₃. Thermogravimetric analysis (TGA) showed that ZnO silicone rubber compounds are thermally more stable than Al₂O₃; however, the coefficient of thermal expansion of the Al₂O₃ silicone rubber compounds are lower than that of ZnO. Comparison in mechanical strength between the two silicone rubber hybrids indicates that ZnO is a better reinforcement filler, as evidenced in the tensile strength, elongation at break, and modulus at 300% elongation.     

Evaluation of PP/EPDM nanocomposites filled with SiO2, TiO2 and ZnO nanofillers as thermoplastic elastomeric insulators

Abstract

Thermoplastic elastomer, which has important characteristics for cable insulation, was developed by melt blending of polypropylene (PP) with ethylene propylene diene monomer (EPDM) at various blend ratios together with SiO₂, TiO₂ and ZnO nanofillers at fixed loading of 2 vol.-%. The influence of EPDM content and the presence of nanofillers in the blend on burning rate, hydrophobicity and dielectric breakdown strength were investigated. Burning rate of PP/EPDM/ZnO was significantly reduced, implying that there was an improvement in fire retardancy with the addition of ZnO nanofillers in the polymer blend. Both SiO₂ and ZnO filled system showed an improvement in hydrophobicity. Furthermore, dielectric breakdown strength showed higher value in EPDM rich blends. In addition, the presence of nanofillers deteriorated the dielectric breakdown strength of PP/EPDM nanocomposites.     

Mechanical properties,chemical and aging resistance of natural rubber filled with nano‐Al2O3

Al₂O₃ nanoparticles were introduced to natural rubber (NR) to investigate its reinforcement effect on filled NR vulcanizates. The results show that Nano‐Al₂O₃/NR nanocomposites exhibit significantly improved tensile strength, elongation at break, modulus, and tearing strength. Scanning electron microscopy analyses indicate that nanoparticles dispersed in NR matrix at nanoscale and show nano‐reinforcement effect on NR vulcanizates. The aging resistances of filled NR vulcanizates improve. After aging test, tensile strength, tearing strength, and modulus improved, and elongation at break decreased. These attribute to the crosslink maturation reactions, which result in the conversion of polysulfidic linkages into disulfidic and monosulfidic ones. The acid and alkaline resistances of nano‐Al₂O₃‐filled NR vulcanizates improve compared with that of unfilled NR systems. After acid and alkaline test, tensile strength and elongation at break improve, and modulus decrease. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Electrical insulation characteristics of alumina,titania, and organoclay nanoparticles filled PP/EPDM nanocomposites

In this study, nanofillers composed of alumina, titania, and organoclay were separately embedded in 50% polypropylene (PP) and 50% ethylene propylene diene monomer (EPDM) blends. Several formulations of PP/EPDM nanocomposites were prepared using an internal mixer and were molded using a compression mold to produce test samples. The effects of filler loading (2, 4, 6, and 8 vol %) on the dielectric breakdown strength, dielectric properties, hydrophobicity, and flammability were determined. The addition of nanofillers improved the breakdown strength (up to 2 vol %) and increased the dielectric constant and dielectric loss of the PP/EPDM nanocomposites. The hydrophobicity of PP/EPDM/Al₂O₃ increased, whereas the hydrophilicity of PP/EPDM/TiO₂ and PP/EPDM/organoclay increased. Flammability test results showed that PP/EPDM/TiO₂ had a lower burning rate than PP/EPDM/Al₂O₃ and PP/EPDM/organoclay. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41184.     

Thermal,electrical, and mechanical properties of addition-type liquid silicone rubber co-filled with Al2O3 particles and BN sheets

The addition-type liquid silicone rubber (ALSR) co-filled with spheroidal Al₂O₃ and flaky BN was prepared by the mechanical blending and hot press methods to enhance the thermal, electrical, and mechanical properties for industrial applications. Morphologies of ALSR composites were observed by scanning electron microscopy (SEM). It was found that the interaction and dispersion state of fillers in the ALSR matrix were improved by the introduction of BN sheets. Thermal, electrical, and mechanical performances of the ALSR composites were also investigated in this work. The result indicated that the thermal conductivity of ALSR can reach 0.64 W m⁻¹ K⁻¹ at the loading of 20 wt% Al₂O₃/20 wt% BN, which is 3.76 times higher than that of pure ALSR. The addition of Al₂O₃ particles and BN sheets also improve the thermal stability of ALSR composites. Moreover, pure ALSR and ALSR composites showed relatively lower dielectric permittivity (1.9–3.1) and dielectric loss factor (<0.001) at the frequency of 10³ Hz. The insulation properties including volume resistivity and breakdown strength were improved by the introduction of flaky BN in the ALSR matrix. The volume resistivity and characteristic breakdown strength E₀ are 6.68 × 10¹⁵ Ω m and 93 kV/mm, respectively, at the loading of 20 wt% Al₂O₃/20 wt% BN. In addition, the mechanical characteristics including elongation at break and tensile strength of ALSR composites were also enhanced by co-filled fillers. The combination of these improved performances makes the co-filled ALSR composites attractive in the field of electrical and electronic applications.     

Acrylonitrile‐butadiene‐styrene nanocomposites filled with nanosized alumina

A polymer nanocomposite was produced by acrylonitrile‐butadiene‐styrene (ABS) and α‐alumina was prepared through sol‐gel process using aluminum nitrate and citric acid. The particle size was analyzed by X‐ray diffraction and scanning electron microscopy (SEM) studies. The nanocomposites were characterized through tensile strength, Young's modulus, strain% at break, flexural strength, flexural modulus, and impact strength. The ABS/Al₂O₃ nanocomposites are found to have slightly higher Young's modulus, but lower tensile strength, strain% at break, flexural and impact strength than the virgin ABS. But its flexural modulus increases with increasing Al₂O₃ content in ABS matrix. The d‐spacing was calculated in nanocomposites to evaluate the interaction between Al₂O₃ and ABS. The particle distributions in nanocomposites were studied by SEM. The fractured surfaces of tensile test samples were also examined through SEM and show that the ductile fracture of ABS is converted to brittle fracture with addition of Al₂O₃. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Enhanced dielectric breakdown strength in Ni2O3 modified Al2O3-SiO2-TiO2 based dielectric ceramics

Dielectric ceramics have raised particular interest since they enable pulsed-power systems to achieve high voltage gradient and compact miniaturization. In this work, x wt%Ni₂O₃ doped Al₂O₃-SiO₂-TiO₂ based dielectric ceramics were prepared using conventional solid-state reaction and the effects of Ni₂O₃ on the crystal structure, dielectric properties and dielectric breakdown strength were investigated. It was found that with the doping of Ni₂O₃, the Al₂O₃-SiO₂-TiO₂ based dielectric ceramics became denser and the distribution of each phase was more uniform. For the composition of x?=?2.0, the dielectric breakdown strength was increased into 82.1?kV/mm, more than twice compared with that of the undoped one. In addition, the relationship between the dielectric breakdown strength and the resistance of Al₂O₃-SiO₂-TiO₂ based dielectric ceramics was discussed. The results show that the doping of Ni₂O₃ is a very feasible way to improve the dielectric breakdown strength and optimize the dielectric properties for the Al₂O₃-SiO₂-TiO₂ based dielectric ceramics.     

Lap shear strength and thermal stability of diglycidyl ether of bisphenol a/epoxy novolac adhesives with nanoreinforcing fillers

Nanoreinforcing fillers have shown outstanding mechanical properties and widely used as reinforcing materials associated to polymeric matrices for high performance applications. In this study, a series of multiwalled carbon nanotubes (MWCNTs)‐, nano‐Al₂O₃‐, nano‐SiO₂‐, and talc‐reinforced epoxy resin adhesives composites were developed. The influence of different types and contents of nanofillers on adhesion, elongation at break, and thermal stability (under air and nitrogen atmospheres) of diglycidyl ether of bisphenol A (DGEBA)/epoxy novolac adhesives was investigated. A simple and effective approach to prepare adhesives with uniform and suitable dispersion of nanofillers into epoxy matrix was found to be mechanical stirring combined with ultrasonication. Transmission electron microscopic and scanning electron microscopic investigations revealed that nanofillers were homogeneously dispersed in epoxy matrix at optimized nanofiller loadings. Adhesion strength was measured by lap shear strength test as a function of nano‐Al₂O₃ and MWCNTs loadings. The results indicated that the lap shear strength was significantly increased by about 50% and 70% with addition of MWCNTs and nano‐Al₂O₃ up to a certain level, respectively. The highest lap shear strength was reached at 1.5 wt % of nano‐Al₂O₃ loading. MWCNTs at all loadings (except 3 wt %) and nano‐Al₂O₃ have enhanced onset of degradation temperature and char yield of the adhesives. By combined incorporation of 0.75 wt % nano‐Al₂O₃ and 0.75 wt % MWCNTs into the epoxy novolac/DGEBA blend adhesives a synergistic effect was observed in the thermal stability of the adhesives at high temperatures (800°C). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40017.     

辐射改性电缆护套管的性能研究

采用低密度聚乙烯/乙烯-醋酸乙烯（PE-LD/EVA）为电缆料的主体基材,氢氧化镁［Mg(OH)2］为主阻燃剂,研究了乙烯-辛烯共聚物（POE）和有机蒙脱土（OMMT）对电缆料力学性能和阻燃性能的影响;并利用γ射线交联技术,探讨了辐射剂量对材料力学性能和阻燃性能的影响。结果表明,随着POE用量的增加,材料的拉伸强度和断裂伸长率增加,但硬度降低;OMMT的添加量为4份时,其与Mg(OH)2可以产生最佳的协同效应,改善了材料的力学性能和阻燃性能;当辐照剂量在90～100 kGy时,PE-LD/EVA/Mg(OH)2/OMMT＝50/50/60/4的共混体系的综合性能达到比较理想的水平,其极限氧指数超过32 ％,拉伸强度为11 MPa,断裂伸长率超过900 ％。     

Design and properties of polyarylene ether nitrile copolymers with improved elongation at break

Polyarylene ether nitrile (PEN) based on biphenol exhibits a high glass transition temperature of 216°C, a high tensile strength of 110 MPa, and low elongation at break of approximately 4%. A series of PEN random copolymers with improved elongation at break were synthesized using various bisphenol compounds and 2,6-dichlorobenzonitrile (DCBN). The resulting PEN random copolymers exhibited a high glass transition temperature and thermal stability up to 513°C in a nitrogen atmosphere. PEN copolymers were amorphous and could easily be cast into transparent films with a tensile strength of 97.93–117.88 MPa and tensile modulus of 2187.98–2558.44 MPa. Most importantly, elongation at break of these PEN copolymers was higher than 13%. PEN copolymer films had a dielectric constant of 3.77–3.89 at 1 kHz and extremely low dielectric loss (<0.02). At the same time, the breakdown strength of PEN was in the range of 137.92–198.19 kV/mm and energy storage density was in the range of 0.32–0.68 J/cm³. Excellent mechanical, thermal, and dielectric properties of PEN make it possible to use them as high-temperature resistant dielectrics to act on high-temperature resistant insulated cables.     

Surface‐Functionalized White Sapphire α‐Al2O3 Platelets as Nanofillers for Vinylester Composites and Heavy Duty Anchoring Systems

Synthetic α‐Al₂O₃ platelets, also referred to as corundum and white sapphire, represent attractive fillers improving the mechanical properties of vinylester‐based chemical anchoring systems. Even in the absence of coupling agents, as verified by scanning electron microscopic (SEM) analyses of fracture surfaces, α‐Al₂O₃ platelets of 200 nm thickness and 5–10 µm size are uniformly dispersed in vinylester resins which are cured by free radical polymerization at room temperature. With increasing content of ultrahard α‐Al₂O₃ platelets (0–40 wt%) the Young's modulus of α‐Al₂O₃ platelet/vinylester composites increases from 3200 to 9000 MPa. However, 1–5 wt% 3‐methacryloyloxypropyl‐trimethoxysilane (MPS) as coupling agent, added to the vinylester resin or preferably used to functionalize α‐Al₂O₃ surfaces in a filler pretreatment step, improves elongation at break (+50%) without sacrificing high stiffness and strength. The X‐ray photoelectron spectroscopy (XPS) analysis confirms the successful surface‐functionalization of α‐Al₂O₃ platelets by using pretreatments with MPS in toluene, acidified ethanol/water or tetrahydrofuran, respectively. The MPS filler pretreatment simultaneously enhances tensile strength (+22%), elongation at break (+50%), and Young's modulus (+12%) as compared to composites containing unmodified filler. According to SEM analyses of composite fracture surfaces, MPS‐mediated functionalization affords significantly improved interfacial adhesion between α‐Al₂O₃ platelets and the polymer matrix.

     

Design and fabrication of electro‐conductive polymer nanocomposites with mechanical and thermal resistance

The commencement of the industrial revolution paved the way for the fabrication of flexible polymers with high‐strength metalloceramics as novel materials of all kinds. Fabricating metal–ceramic/polymer conductive composites is one such dimension followed for the present research work making use of the properties of the three components. Electroless deposition, for permanent metallic coating, was performed to coat Al₂O₃ with metallic Cu followed by the inclusion of the Cu–Al₂O₃ filler into a poly(vinyl chloride) (PVC) matrix. X‐ray diffraction and energy‐dispersive X‐ray studies predicted a prominent growth of metallic Cu crystallites onto Al₂O₃ with an increased average size and variation in elemental composition, respectively, when compared to pristine Al₂O₃. Morphological behaviour via scanning electron microscopy also envisioned uniform Cu coating onto Al₂O₃ and a homogeneous dispersion throughout the polymer matrix. When incorporated into PVC, electrical conductivity analysis highlighted a distinct variation in composite phases from insulating (7.14 × 10^?16 S cm^?1) to semiconducting behaviour (8.33 × 10^?5 S cm^?1) as a function of Cu–Al₂O₃ filler. Mechanical behaviour (tensile strength, Young's modulus and elongation at break) and thermal properties of the prepared composites also indicated a substantial improvement in material strength with Cu–Al₂O₃ incorporation. The enhanced electrical conductivity along with improved thermomechanical status with significant filler–matrix interaction permits the potential usage of such novel composites in a range of state‐of‐the‐art semiconducting electronic devices. © 2018 Society of Chemical Industry     

Polyimide dielectric nanocomposites containing functional nanofillers based on multilayer structure: Design,preparation, and properties

Polyimide (PI) dielectric nanocomposites containing functional nanofillers based on layered structure (single-layer: BT@Al₂O₃@PI, double-layer: PI/BT@Al₂O₃@PI, three-layer: PI/BT@Al₂O₃@PI/PI) were designed and prepared by using PI as matrix, barium titanate (BT)@alumina (Al₂O₃) as nanofillers through in-situ polymerization compounding technology. FTIR tests indicated that PI and PI dielectric nanocomposites have been synthesized successfully. The molecular mass of BaTiO₃@Al₂O₃@PAA oligomer was higher than that of pure PAA when BT and Al₂O₃ nanofillers were incorporated simultaneously, as verified by GPC and intrinsic viscosity tests. XRD analysis showed that the addition of nanofillers destroyed the order of PI molecular structure and reduced the arrangement density of PI molecular chains. Both FESEM and HRTEM observations showed that the nanofillers were homogeneously dispersed in the PI matrix, contributing to the property improvements of PI dielectric nanocomposites. TGA results indicated that adding nanofillers improved the thermal stability and heat resistance of PI dielectric nanocomposites. The dielectric constant of PI/BT@Al₂O₃@PI double-layer nanocomposites was between the single-layer nanocomposites and pure PI. Due to the effective medium theory, the dielectric constant of three-layer PI/BT@Al₂O₃@PI/PI nanocomposites containing 5 wt% BT@Al₂O₃ reached 5.43. This work can be expected to provide an effective strategy to fabricate PI dielectric nanocomposite films for energy storage applications.     

Graphene nanoplatelets/barium titanate hybrid nanoparticles via ball milling for enhanced dielectric and mechanical properties of fluorosilicone rubber composites

Dielectric elastomers have been widely used in flexible actuators, artificial muscles, soft generators, etc. However, there are still challenges in fabrication of dielectric elastomers with enhanced dielectric and mechanical properties through simple and environmentally friendly compound method. In this paper, graphene nanoplatelets (GNPs) and BaTiO₃ (BT) hybrid nanofillers are prepared by co-ball milling and then introduced into fluorosilicone rubber (FSR) to obtain composites with improved dielectric and mechanical properties. The X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscope results confirm the successfully exfoliation of GNP. With the increase of GNP content, the tensile strength and dielectric constant of FSR/GNP/BT nanocomposites both increase without the sacrifice of flexibility, while the dielectric loss tangent can be kept as low as 10^?2 magnitude. The FSR-G7B30-BM composite exhibits a dielectric constant of 14.54 at 100 Hz, and the dielectric loss tangent of 0.016 at 100 Hz. Besides, the FSR-G7B30-BM composite displays the tensile strength of 1.19 MPa, and elongation at break of 332.12%. This work provides a facile strategy to design dielectric elastomers, which shows promising applications in modern electronic devices.     

Study on poly(ether ether ketone)/organically modified montmorillonite composites

Abstract

Novel poly(ether ether ketone) (PEEK)/organically modified montmorillonite (OMMT) composites containing 0–10 wt-% fractions of OMMT were prepared by melting blending method and the microstructure, thermal and mechanical properties were investigated using different characterisation techniques. X-ray diffraction and transmission electron microscopy showed that the OMMT was well dispersed with microscale in the PEEK matrix. Differential scanning calorimetry indicated that the glass transition temperature T _g and melt temperature T _m of PEEK/OMMT composites (POMCs) were hardly affected by the addition of OMMT, while the crystal temperature T _c decreased when the amount of OMMT excessed 1 wt-%. The data of thermogravimetric analysis exhibited that the thermal stability of POMCs in higher temperature region was better than that of pure PEEK. The results of mechanical properties test revealed that modulus and strength of POMCs increased with the content of OMMT, whereas the elongation at break and impact strength of POMCs decreased.     

Properties of Ferrite-Filled Natural Rubber Composites

Nickel zinc ferrite (Ni-ZnFe₂O₄)-filled natural rubber (NR) composite was prepared at various loading of ferrite. The tensile properties included in this study were tensile strength, tensile modulus and elongation at break. The tensile strength and elongation at break of the composites increased up to 40 parts per hundred rubber (phr) of ferrite and then decreased at higher loading whereas the tensile modulus was increased gradually with increasing of ferrite loading. Scanning electron microscopy (SEM) was used to determine the wettability of filler in rubber matrix. From the observation, the increase of filler loading reduced the wettability of the filler. Thermal stability of the composites was conducted by using a thermogravimetry analyser (TGA). The incorporation of ferrite in NR composites enhanced the thermal stability of NR composites. The swelling test results indicate that the swelling percentage of the composites decreased by increasing of ferrite loading. The initial permeability, μ_i and quality factor, Q of magnetic properties of NR composites achieved maximum value at 60 phr of ferrite loading for frequency range between 5000–40,000 kHz. The maximum impedance, Z _max of the NR composites was at the highest value at 80 phr ferrite loading for frequency range between 200–800 MHz.     

Role of copper alumina nanoparticles on the performance of polyvinylchloride nanocomposites

Poly(vinyl chloride) (PVC) nanocomposites with different contents of copper alumina (Cu-Al₂O₃) nanoparticles were prepared by the solution casting method. The effects of the nanoparticles on structural, thermal, electrical, contact angle and mechanical properties were thoroughly examined. The presence of Cu-Al₂O₃ in the macromolecular chain was confirmed through Fourier transform infrared (FTIR) spectroscopy. The X-ray diffraction (XRD) analysis of PVC nanocomposites showed the systematic arrangement of Cu-Al₂O₃ nanoparticles within the polymer, which indicated the higher crystallinity of the nanocomposites. The surface morphology of PVC was changed into hemispherical shaped particles by the inclusion of nanofiller was analyzed from SEM images. The glass transition temperature of the nanocomposites obtained from differential scanning calorimetry (DSC) was found to be increased with an increase in loading of nanoparticles in the polymer. The AC conductivity and dielectric studies revealed that the inclusion of nanofiller increases the electrical properties of the material and the composite with 7 wt.% sample showed the maximum conductivity and dielectric constant. The mechanical properties such as modulus, tensile strength, hardness, and impact properties of the PVC nanocomposites were significantly enhanced by the reinforcement of nanoparticles into the PVC matrix. The reinforcing mechanism behind the increase in tensile strength with the addition of nanoparticles was correlated with different theoretical models. The highest mechanical and electrical properties were observed for 7 wt.% Cu-Al₂O₃ loaded nanocomposite. Contact angle measurements of PVC with various loadings of Cu-Al₂O₃ nanofillers demonstrated that the nanoparticle attachment increased the hydrophobicity of the polymer matrix.     

Properties of thermally conductive silicone rubbers filled with admicellar polymerized polypyrrole-coated Al2O3 particles

Polypyrrole (PPy) nanolayers were introduced on the surface of alumina (Al₂O₃) particles via admicellar polymerization. The properties of silicone rubbers (SRs) filled with PPy-coated Al₂O₃ and pristine Al₂O₃ as thermally conductive fillers were studied and compared. The results demonstrate that the addition of PPy-coated Al₂O₃ leads to a better interfacial compatibility but lower cross-linking density of the composites than pristine Al₂O₃. The improvement in the compatibility and the decrease in the cross-linking density are paradoxes in affecting mechanical properties. The improvement in the compatibility shows a slight predominance on the strength at low-filler contents. Lower cross-linking density of modified-Al₂O₃/SR composites led to a better processing performance and a higher maximum filler loading amount than the pristine Al₂O₃/SR composites, which is beneficial to increasing the thermal conductivity and maintaining a relatively good strength. The PPy-coated Al₂O₃/SR composite with 83 wt% filler content has a thermal conductivity of 1.98 W/(m K) and a tensile strength of 2.9 MPa, and the elongation at break was 63%. Functionalized fillers by admicellar polymerization used in the fabrication of filler/SR composites not only improve the interfacial compatibility but also optimize and expand the functions of the composites, which has great significance for the production and application of thermally conductive SR in some branches of industry (automotive, electrical engineering, etc.) in the future.     

Effect of alumina on the structure and properties of polyimide matrix films

To improve the properties of polyimide (PI), different mass fractions of alumina (Al₂O₃) nanoparticles, unmodified or modified by KH550, were incorporated into PI matrix to form PI/Al₂O₃ hybrid films by in situ polymerisation. The effects of Al₂O₃ additives on the structure, dielectric and mechanical properties of the films were studied. Fourier transform infrared spectroscopy confirmed the successful preparation of PI/Al₂O₃ hybrid films, and the microstructures of the samples showed a more uniform dispersion of the modified Al₂O₃ nanoparticles than the unmodified ones in the matrix. The dielectric constant of the films increased with increasing filler content, and the maximum electrical breakdown strength of 311 MV m^?1 was obtained with a filler content of 8.0 wt-% modified Al₂O₃ in the matrix. Both unmodified and modified Al₂O₃-reinforced PI hybrids demonstrated improved mechanical properties compared with the PI matrix. Moreover, the properties of films with Al₂O₃ modified by KH550 were better.     

Significantly enhanced energy density of amorphous alumina thin films via silicon and magnesium co-doping

The different Si-Mg co-doping content was explored to improve the dielectric properties of amorphous Al₂O₃ thin film. According to the analysis of DSC, FT-IR, and XPS spectra, it can be confirmed that a novel structure of glass network is formed in the co-doped Al₂O₃ thin film. More importantly, compared to Al₂O₃ thin film, the leakage current of (Al_.97Si_.02Mg_.01)₂O_y thin film is reduced by 2 orders of magnitude and the breakdown strength is improved from 276?MV/m to 544?MV/m. The corresponding energy density of the modified sample is up to 9.2?J/cm³, which is an enhancement of 6.2?J/cm³ over that of the undoped Al₂O₃ thin film. Based on finite element analysis, the simulation results show that the applied electric field is mainly focused on the glass network, which could strengthen the stability of Al₂O₃ structure and decrease the breakdown probability of the films. From the viewpoint of defect chemistry, another reason for the enhancement of the dielectric properties is that Si-Mg co-doping results in the generation of cation vacancies and thus the formation of oxygen vacancies could be effectively prevented. This work could provide a new design strategy for high-performance dielectric capacitor devices.