Defect Levels Research Articles

First-principles investigation of positively charged and neutral oxygen vacancies in amorphous silica.

The structural parameters, electron localization functions, electron paramagnetic resonance (EPR) parameters, formation energies, and thermodynamic transition levels of various oxygen vacancy defects in amorphous silica are comprehensively and integrally investigated by using density functional theory. The trends of changes in the oxygen vacancy defect structure and electron localization induced by the increase in distance between defective silicon atoms are clearly identified. It is shown that the dimer configuration may be the potential structure of the Eδ' center. For the back-projected unpuckered configuration and the puckered configuration, whose EPR parameters are more consistent with the experimental values of the Eγ' center, the unpaired electron localized on the sp3 hybridized silicon atom is a common feature. Due to the three-coordinated oxygen atom in the forward-oriented configuration, the EPR parameters are closest to those of the Eα' center. Transformations of oxygen vacancy defects under different charge states are studied by sequentially adding and removing electrons. The thermodynamic transition level analysis reveals that the dimer and forward configurations may behave as deep traps for electron accumulation. The back-projected puckered fourfold-coordinated and fivefold-coordinated configurations are comparatively stable and may be able to function as shallow traps for electron transport. The neutral double unpuckered, neutral back-projected puckered fourfold-coordinated, and neutral back-projected unpuckered configurations are more likely to lose electrons during hole trapping. As the bias voltage is repeatedly changed, the defect density of the puckered configuration may reduce, while that of the dimer and unpuckered configuration may take an opposite trend.

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4‐(2‐Hydroxyethyl)piperazin‐1‐ium iodide (PZOI) is a functional ammonium salt that can simultaneously reduce shallow/deep‐level defect densities by passivation effect and form 2D component, respectively. These advances reduce the energy loss of single‐junction devices and significantly enhance the efficiency and stability of perovskite/organic tandems. More details are discussed in the article by Li et al. on page 1819—1827.image

Understanding epitaxial growth of two-dimensional materials and their homostructures.

The exceptional physical properties of two-dimensional (2D) van der Waals (vdW) materials have been extensively researched, driving advances in material synthesis. Epitaxial growth, a prominent synthesis strategy, enables the production of large-area, high-quality 2D films compatible with advanced integrated circuits. Typical 2D single crystals, such as graphene, transition metal dichalcogenides and hexagonal boron nitride, have been epitaxially grown at a wafer scale. A systematic summary is required to offer strategic guidance for the epitaxy of emerging 2D materials. Here we focus on the epitaxy methodologies for 2D vdW materials in two directions: the growth of in-plane single-crystal monolayers and the fabrication of out-of-plane homostructures. We first discuss nucleation control of a single domain and orientation control over multiple domains to achieve large-scale single-crystal monolayers. We analyse the defect levels and measures of crystalline quality of typical 2D vdW materials with various epitaxial growth techniques. We then outline technical routes for the growth of homogeneous multilayers and twisted homostructures. We further summarize the current strategies to guide future efforts in optimizing on-demand fabrication of 2D vdW materials, as well as subsequent device manufacturing for their industrial applications.

Defect-controlled fabrication of reduced graphene oxide/ZnO/PMMA-based solid-state optical limiting filters with SA/RSA switching property

A solid-state optical limiting filter was fabricated by noncovalently functionalizing a graphene-based nanocomposite with a polymer. Graphene oxide was reduced by varying reducing agent concentration and functionalized with metal oxide nanoparticles to enhance electronic transitions and third-order nonlinear optical characteristics. The nanocomposite was dispersed over the PMMA polymer framework, and thin films with μm-scale thickness were fabricated using the dip coating method. XRD analysis confirmed the wurtzite crystal structure of ZnO nanoparticles and the amorphous nature of PMMA. The carbon structural integrity was analyzed using Raman spectra. Linear optical studies revealed a redshift in the π-π* transition peak in rGO, suggesting enhanced conjugation. Third-order nonlinear refraction and absorption properties were assessed using the Z-scan technique, revealing a switching behavior in nonlinear absorption at different input intensities. An increase in the relative concentration of sp2 domains enhanced the nonlinear absorption. Optical limiting potential, determined using open aperture Z-scan data, yielded a threshold value of 0.066 GW/cm2. This study aims to develop a solid-state optical filter with a high laser damage threshold by adjusting the reduction rate, tuning defect levels, and analyzing its effect on the optical limiting potential.

Optical and electrochemical studies on single-phase ZnSnO3 nanostructures—A photosensitive approach

A sol-gel-combustion reaction approach is used to synthesize nanocrystalline, single-phase ZnSnO3 phosphor. XRD with the Rietveld refinement investigation reveals a previously unreported orthorhombic structure of ZnSnO3. FTIR analysis confirms the formation of the ZnSnO3 phase. Microstructural SEM and TEM examinations affirm the petal-like morphology of the ZnSnO3 nanostructure. UV-DRS analysis signifies ZnSnO3 as a semiconducting material with a lowest energy band gap of 2.94 eV, which has never been recorded before. Photoluminescence (PL) studies reveal defect-related emission in ZnSnO3. Cyclic voltammetry measurements confirm the redox process and photo-generated carrier recombination via defect levels. ZnSnO3 is identified as a p-type semiconductor by Mott-Schottky analysis. When irradiated with 397 nm UV light, the semiconducting nanostructures emit near-white light. Finally, the investigation of ZnSnO3 nanopowder for latent fingerprint impressions reveals an unusual diffuse reflection and high-resolution images under a sodium vapour lamp and LASER-LED illumination.

Gas-phase and liquid-phase purification of plastic waste derived carbon nanotubes: Effect of purification agent and operational parameters

The preparation of carbon nanotubes (CNTs) by catalytic pyrolysis of waste plastics is one of the most promising technologies to realize the harmless and high-value recycling of waste plastics. However, there are limited studies on the purification of waste-derived carbons, which is of significance for downstream applications. In this paper, the effects of different gas-phase purification conditions (temperature, gas type), liquid-phase purification (hydrochloric and nitric acid reflux), and combined gas-liquid purification on the properties of CNTs prepared from waste plastics were investigated. The as-obtained and purified CNTs were characterized using SEM, TEM, TPO, XRD, XPS, Raman spectroscopy, and FTIR spectroscopy. Results showed that operational temperatures have distinct impacts on the properties of CNTs during gas-phase purification. An appropriate temperature range for gas-phase purification was determined, with temperatures around 450 °C for air, 650 °C for CO2, and 700 °C for steam respectively, so that the amorphous carbon could be removed and the graphitization of CNTs was retained. Approximately 93 wt% of the metal catalyst particles could be removed with acid treatment for 4 h. In addition, carboxyl and hydroxyl functional groups were introduced to CNTs after acidic treatment. Furthermore, it was found that the approach combining CO2 treatment and nitric acid washing yielded CNTs with relatively higher quantities and lower defect levels. Results showed the properties of CNTs varied from the purification methods, which could meet different needs based on the downstream specific application requirements.

Oriented growth of 5-inch optical polycrystalline diamond films by suppressing dark features

Optical diamond materials are essential for infrared optical windows, microwave windows, and laser windows due to their exceptional properties. However, dark features inside the diamond are significant factors limiting optical properties, particularly at high deposition rates. This work focuses on adjusting crystallographic parameters to prepare (110) oriented optical-grade polycrystalline diamond films, aiming to mitigate dark features. Diamond films deposited via microwave plasma chemical vapor deposition (MPCVD) exhibit discernible quality stratification. Characterization analysis of diamond film samples with varying levels of black defects reveals a correlation: films with higher dark feature content tend to exhibit a preference for the (111) orientation, accompanied by a significant presence of penetration twins and interstitial voids. Conversely, transparent diamond films demonstrate a prominent (110) orientation, featuring numerous contact twins that alleviate competition from penetration twins and original grains during growth. Electron backscatter diffraction (EBSD) and scanning electron microscope (SEM) results reveal that transparent diamond films cultivated with a pronounced preference for the (110) orientation manifest consistent and seamless contact twins, leading to fewer dark features and improved optical transmittance. In contrast, (111) oriented diamond film exhibits numerous penetration twins, and holes form between them. Based on the analysis, 5-inch optical polycrystalline diamond films with (110) orientation were achieved successfully by suppressing dark features.

The Effect of Oxygen Vacancy Defects on the Structure and Electrochemical Behaviors of LiMn0.65Fe0.35PO4 Cathode

The presence of oxygen vacancy defects significantly impacts the crystal structure and electrochemical attributes of phosphate cathodes. In this investigation, LiMn0.65Fe0.35PO4 materials with varying levels of oxygen vacancy defects were synthesized via hydrogen plasma-induced reduction. It was observed that the content of oxygen vacancy defects on the crystal surface increased proportionately with the rise in hydrogen (H2) flow rate. Notably, the LMFP-3 sample, prepared with an H2 flow rate of 10 ml min−1, demonstrated superior electrochemical performance, characterized by a 159.7 mAh g−1 discharge capacity at 0.1 C and a remarkable 99.8% capacity retention at 5 C after 200 cycles. This enhancement in electrochemical performance is attributed to the improved intrinsic conductivity of the LiMn0.65Fe0.35PO4 material due to the presence of oxygen vacancy defects. However, it is important to note that an excessively high H2 flow rate can lead to the formation of Fe2P impurities, which hinder lithium ion (Li+) diffusion. Furthermore, theoretical calculations conducted using density functional theory provide a rational explanation for the observed improvement in electronic conductivity. The introduction of oxygen vacancy defects results in a significant reduction in the Band gap, which is highly beneficial for enhancing the intrinsic conductivity of the LiMn0.65Fe0.35PO4 materials.

Energy transfer and a novel SBR thermometry of SrY2O4:Sm3+/Eu3+ phosphor based on redshift of charge transfer band edge

In this study, a solid-state reaction was employed to synthesize SrY2O4: Sm3+, SrY2O4: Eu3+ and SrY2O4: Sm3+/Eu3+ phosphors. An intriguing redshift phenomenon from charge transfer band (CTB) edge was investigated for single-band ratiometric (SBR) thermometry applications. The phosphors synthesized exhibited an orthogonal CaFe2O4 structure with Pnam (62) space group. The Y3+ sites from host lattice were most likely to be replaced by Sm3+/Eu3+ ions. The sample of SrY2O4: 0.03 Sm3+/0.3Eu3+ showed a large degree of agglomeration with elongated particles, having an average size of approximately 4 μm. The energy bandgap decreased due to increased surface imperfections, resulting in enhanced defect level concentration. The dipole-dipole interaction could be used to explain energy transfer (ET) of Sm3+-Sm3+ and Sm3+-Eu3+. Furthermore, the energy transfer (ET) efficiency of Sm3+→Eu3+ in Sr2YO4 reached 77.7 %. The sample exhibited a good thermal stability (90.956 %@423 K) with Ea of 0.31 eV, which was an important parameter for broadening thermometry range. A thermometry strategy utilized this redshift phenomenon from CTB edge with anti-thermal quenching behavior and other peaks or bands with thermal quenching was therefore proposed. The high Sr value of 1.533 % K−1@298 K provides a great potential for optical thermometry application, contributing significantly to the advancement of single band ratiometric thermometry technologies.

Preparation of SnOx/N-GQDs composites with oxygen-rich vacancies for enhanced photoelectric properties

SnOx with oxygen-rich vacancies and SnOx/N-GQDs (Nitrogen-doped graphene quantum dots) composites were prepared by high temperature annealing and hydrothermal method, respectively. The annealing process introduced a large number of oxygen vacancies and produced defect energy levels in the band gap. The existence of the defect level effectively reduced the band gap of SnOx, enlarged the optical absorption range, and improved the light utilization. The introduction of N-GQDs also improved the carrier density and electron transport rate, and extended the carrier lifetime (τ = 7.44 ms). I-T (Transient photocurrent response) analysis results showed that when the mass ratio of Sn/SnO2 was 1:4 and N-GQDs doping content was 1 wt%, the transient photocurrent response of SnOx/N-GQDs could reach 5.51 × 10−4 A/cm2, which was 25 times higher than that of pure SnO2, and the photocurrent response value maintained 80.1 % within 500 s. EIS (Electrochemical impedance) and M-S (Mott-Schottky) analyses indicated that the appropriate amount of oxygen vacancies and N-GQDs were beneficial to reducing the charge transport resistance, inhibiting the electron-hole pair recombination, and increasing the carrier density of SnOx. The results show that SnOx/N-GQDs composites present the improved photoelectric properties with the addition of oxygen vacancies and N-GQDs, which provides a new idea for promoting the properties of semiconductors.

Quality control of garment product using DMAIC Six Sigma

Quality control is intended to ensure that the products are in accordance with the predefined standards. PT. XYZ is a garment company that manufactures products with global target market. Hence, product quality assurance becomes an important issue for PT. XYZ. This research focuses on the Just Brand-MCJA216142 jacket product at the sewing work station on line-4 of PT. XYZ. Preliminary observations show that the number of reworked-products was experiencing an increasing trend. This study aims to determine whether the company has carried out quality control properly. Specifically, the research objectives are to identify the type and level of product defects, identify the factors causing product defects, and provide proper improvement suggestions to reduce the occurrence of product defects. This study applied DMAIC (Define–Measure–Analyze–Improve–Control) Six Sigma concept. The results showed that the quality of the Just Brand-MCJA216142 jacket product has exceeded the Indonesian industry average and is classified as the USA industry average. However, quality improvement is still needed since the products are targeted for the export market. Based on Pareto diagram at the Analyze stage, it was found that the most dominant defects occurred in the Just Brand-MCJA216142 jacket production process were broken threads and puckering. The frequency of occurrence for these two types of defect reaches 23% of the total 16 types of defects. The defects were caused by human, machine, material, method, and environmental factors. Recommendations for improvement at the Improve stage are based on root cause analysis of each causative factor that is identified using a fishbone diagram. This research results strengthen the previous related researches regarding the effectivity of DMAIC Six Sigma for analyzing quality control of products.

Inference of oxidative stress in patients with hypothyroidism

Introduction and aim. Oxidative stress is one of the complications that accompany defects in thyroid hormone levels. This study was designed to evaluate oxidative stress markers in patients with hypothyroidism. Material and methods. This case control study was comprised of forty-two hypothyroid patients aged 36–46 years and forty age matched (35–43 years) healthy control participants randomly selected from the Endocrine Clinic of Al-Yarmook Hospital in Iraq. Blood levels of thyroid hormones malondialdehyde, glutathione, and paraoxonase-1 were assessed. Body mass index was calculated for each patient and control participant. Results. Regarding the data of oxidative stress markers in hypothyroid patients compared to controls, a significant elevation was reported in blood levels of malondialdehyde and a significant reduction was found in blood levels of glutathione (p=0.031). On the other hand, the blood levels of paraoxonase-1 were significantly different in hypothyroid patients compared with the control. Conclusion. Elevated blood levels of malondialdehyde and declined blood levels of glutathione in hypothyroid patients are a signal of oxidative stress and consequently increase the risk of cardiovascular complications.

Quality Control of Kinasih Bread Products Using Statistical Quality Control and Failure Mode and Effect Analysis Methods

Roti Kinasih UMKM is a business that focuses on the culinary sector by producing various types of bread. The business process carried out at this UMKM is a Make to Order system where products are made after receiving orders from customers. One problem that often arises is the inability to control product quality. Having defective products has a big impact on MSMEs because the costs incurred increase. Based on the existing problems, the Statistical Quality Control and Failure Mode And Effect Analysis methods were chosen to determine the factors causing product defects in UMKM Roti Kinasih. The aim of this research is to determine the level of defects in Kinasih bread products and carry out quality control measures using statistical methods. After processing and analyzing the data, it was found that the burnt bread defect and the sinking bread defect were said to be in an uncontrolled condition and needed recommendations for improvement. The highest RPN value for the burnt bread defect was 245 with the overtime baking failure mode, while the RPN value for the sinking bread defect was 175 with the too cold room temperature failure mode.

Enhancing efficiency and stability of inverted perovskite solar cells through synergistic suppression of multiple defects via poly(ionic liquid)-buried interface modification

The stability of perovskite solar cells (PSCs) is adversely affected by nonradiative recombination resulting from buried interface defects. Herein, we synthesize a polyionic liquid, poly(p-vinylbenzyl trimethylammonium hexafluorophosphate) (PTA), and introduce it into the buried interface of PSCs. The quaternary ammonium cation (N(–CH3)3+) in PTA can fill the vacancies of organic cations within the perovskite structure and reduce shallow energy level defects. Additionally, the hexafluorophosphate (PF6−) in PTA forms a Lewis acid-base interaction with Pb2+ in the perovskite layer, effectively passivating deep energy level defects. Furthermore, hydrogen bonding can be established between organic cations and the PF6− anion, preventing the formation of shallow energy level defects. Through this synergistic mechanism, the deep and shallow energy level defects are effectively mitigated, resulting in improved device performance. As a result, the resulting treated inverted PSC exhibits an impressive power conversion efficiency (PCE) of 24.72 %. Notably, the PTA-treated PSCs exhibit remarkable stability, with 88.5 % of the original PCE retained after undergoing heat aging at 85 °C for 1078 h, and 89.1 % of the initial PCE maintained following continuous exposure to light for 1100 h at the maximum power point. Synergistically suppressing multiple defects at the buried interface through the use of polyionic liquids is a promising way to improve the commercial viability of PSCs.

Quality Control of Ceramic Wall Products Six Sigma Method with Dmaic Tools and Failure Mode and Effect Analysis (FMEA)

Considering the importance of increasingly rapid industrial development, business people must be aware of the orientation towards product quality. The manufacturing industry has an important role in industrial development. It is hoped that it will be able to grow and have advantages in industrial development, therefore it is necessary to improve and increase product quality. The company continues to strive to maintain and improve product quality and increase productivity so that customers are satisfied with the products produced. One way that needs to be done is to reduce the number of defective products in the production process. This effort is one way of continuous improvement carried out by PT. ABC and companies operating in the same field. The ceramic wall production process has relatively high demand but still has a high level of defects. Based on information on production data and data on the number of defects for the period January – September 2023, wall ceramic production has a defect rate of 3.86%. Companies must reduce the number of defects to achieve company targets. This research aims to improve the production process of wall ceramics by minimizing the number of defective products. This research uses the six sigma method with the DMAIC (Define, Measure, Analyze, Improve, Control) tool assisted by the FMEA (Failure Mode and Analysis) method. Corrective action to reduce defects based on the 5 Why analysis is to find out what the problem is and ask "why" and "what is the root of the problem". The research results show that there are 4 types of defects which have a large number of defects, namely Rupture Defects, Application Defects, Peeling Defects and Hole Defects. From the research results, solutions were obtained for the emergence of several types of defects in the wall ceramic production process, namely by providing planning suggestions and corrective actions which are discussed this time. At the defect calculation stage, Broken produces a DPMO value of 29.362 with a sigma level of 3.39 with a sigma level of 3.48, Defect Peeled produces a DPMO value of 28.044 with a sigma level of 3.38, and holes are defective. resulting in a DPMO value of 26,020 with a sigma value of 3.45 from the data calculation results, it is still not enough to meet the company's target at the sigma level, therefore the company must make quality improvements to achieve the main target at the sigma level.

Defect‐Driven Light Perception and Memristor Storage with Phase Transition in Vanadium Dioxide

AbstractTunable optical information storage is crucial in artificial retinal systems for mimicking neurobiological visual characteristics. The perception and storage of light signals rely heavily on the regulation of the conductivity states of memristor materials (e.g., transition metal oxides). Controlling light memristor behavior via defects and polymorphic phases remains underexplored and differs from traditional plasticity training via repeated testing. In this study, defect‐driven ultraviolet light perception and memristor storage with phase transitions in vanadium dioxide (VO2) thin films are presented. The effects of oxygen defects and the corresponding polymorphic phases on ultraviolet light memristors are investigated. The dependence of phonon vibrations and insulator–metal transition behavior on defect levels are revealed. Self‐doping and polymorphs enable VO2 to exhibit distinct ultraviolet memristor performance. It is anticipated that defect‐driven light memristors significantly contribute to the realization of artificial synaptic devices and the implementation of advanced electronic neuron systems.

Optically Active Defect Engineering via Plasma Treatment in a MIS‐Type 2D Heterostructure

AbstractAt the interface of 2D heterostructures, the presence of defects and their manipulation play a crucial role in the interfacial charge transfer behavior, further influencing the device functionality and performance. In this study, the impact of deliberately introduced photo‐active defects in the h‐BN layer on the interfacial charge transfer and photoresponse performance of a metal‐insulator‐semiconductor type heterostructure device is explored. The formation and concentration of defects are qualitatively controlled using an inductive coupled plasma treatment method, as evidenced by enhanced h‐BN defect emission and more efficient optically induced doping of graphene at the graphene/h‐BN interface. Besides, the use of the h‐BN layer between graphene and WS2 not only suppresses charge carriers in the dark state, but also promotes the separation of photo‐generated electron‐hole pairs and interfacial charge transfer due to the existence of defect levels, leading to orders of magnitude improvement in the light on/off ratio and self‐driving performance of the heterostructure photodetector. This strategy of controlling defect states in the insulating layer provides a new approach to optimize the charge transfer processes at the 2D interfaces, so as to expand its potential applications in the fields of electronic and optoelectronic devices.

Unraveling the outstanding catalytic efficiency of unprocessed bone-derived biochar: A deep dive into the mechanisms of native organic encapsulation and defective nitrogen doping in boosting persulfate activation for tetracycline degradation

Designing efficient non-metallic catalysts for persulfate (PS) activation has attracted broad attention due to their demonstrated immense potential in environmental remediation. In this study, unprocessed pig bone waste was successfully converted into biochars (PBCs) through a straightforward one-step pyrolysis process, which function as efficient PS catalysts for the removal of tetracycline (TC). The results revealed that the endogenous inner layer hydroxyapatite activator (IHA) and the rich native outer layer organic component wrapped with nitrogen-doped additives (OONA) found in raw bone-derived waste biomass collaborate to exert a dual effect of template and surface modification at 900 °C. Notably, under this synergistic action, 900PBC exhibited active defect nitrogen (pyridinic and graphitic nitrogen), sp2-hybridized groups (C = C, C = O, and C = N) and high defect levels (ID/IG = 1.0291), along with a cross-linked micro-mesoporous structure. This unique combination of properties endowed 900PBC with excellent catalytic activity, enabling it to effectively remove 50 mg/L of TC in the PS system within 30 min, primarily through a dual reaction pathway involving oxygen-active species (O2·-, 1O2) and electron transfer (fitting instantaneous-current values to PS concentrations, R2 = 0.95). Density-functional theory calculations confirmed that, within the nitrogen configurations located at defect sites, pyridinic nitrogen exerted a significant influence on the electron cloud density of adjacent carbon networks, subsequently promoting the formation of excited states of PS. Meanwhile, graphitic nitrogen constructed electron bridges with adjacent sp2-hybridized orbitals, facilitating the formation of the metastable complex 900PBC-PS*. Remarkably, 900PBC also exhibited excellent cyclic stability, maintaining a 93 % TC removal rate after four cycles,as well as high tolerance to a broad pH range (3–9), high concentrations of coexisting ions (10 mM), and diverse real-world water bodies. This study offers novel insights into synthesizing high-value biochar from waste bones with high catalytic activity.

Influence of defect degree on corrosion resistance of graphene coating on titanium alloy

Electrophoretic deposition (EPD) is an effective method for preparing graphene coatings with dense and uniform characteristics on complex-shaped substrates, but defects in graphene coatings prepared by EPD are unavoidable, which affects the corrosion resistance of graphene coatings. This study investigates the effect of defect levels(i.e. ID/IG values in Raman spectroscopy analysis) on the corrosion resistance of graphene coatings on titanium alloys by varying EPD parameters and graphene raw material sizes to prepare coatings with different defect levels. Raman spectroscopy and scanning electron microscopy were used to characterize and measure the defect degree of graphene coatings. Open-circuit potential analysis, electrochemical impedance spectroscopy (EIS) and polarization analysis of dynamic potential were used to study the corrosion properties and anti-corrosion mechanism of graphene coatings.The results show that the graphene coating has lower defect level at an electrophoresis voltage of 60 V, deposition time of 20 min, and graphene flakes size of 1 μm achieving a corrosion current density as low as 0.06 μA/cm2. This study reveals the corrosion resistance mechanism of graphene coatings with different defect levels. Graphene coatings with large porosity and defect levels are easily penetrated by corrosive media and then corrode in contact with the substrate. This research provides insights into developing graphene coatings with low defect levels and high compactness, which will significantly enhance the anti-corrosion efficiency of titanium alloys.

Defect Analysis of Packaging Bottle Products Using Six Sigma and Kaizen Methods at PT. XYZ

PT XYZ is a company engaged in manufacturing plastic packaging. The company produces various forms of packaging, one of which is cosmetic bottle packaging. Meanwhile, based on the problems of the production process, various types of product defects such as black spots, leaks, and oil dirt are often found. The company produces the most defective products in 30ml cosmetic bottle products, with a percentage of 3% to 4% of the total production. Based on the above problems, this study aims to determine the level of defects and the sigma value of product quality. In addition, provide suggestions for improvement to reduce the level of product defects at PT XYZ. The methods used are Six sigma and Kaizen. The Six Sigma stages include define, measure, analyze, and improve. The improve stage is assisted by the Kaizen Five M Checklist and Kaizen Five Step Plan. The improve stage is assisted by the Kaizen Five M Checklist and Kaizen Five Step Plan. Based on the results of research with the six sigma method, the percentage of black spot defects is 74%, leaking is 14.1%, and dirty oil is 11.9%. the proposed improvements given are providing 5S training and SOP refreshment, sorting reject products before grinding, cleaning the machine and production area at the end of each shift, replacing blowpin threads and bolts, and others.