Angular absorptance and thermal degradation analysis of TiB2/Ti(B,N)/SiON/SiO2 multilayer solar absorber coating

Multilayer solar selective absorber coatings have been developed in the last few decades. The thermal stability in terms of microstructure gives an insightful understanding of the optical properties of such coatings. In this context, we extensively utilized transmission electron microscopy (TEM) analysis to establish the thermal stability of TiB₂/Ti(B,N)/SiON/SiO₂ coating, under thermal cycling/continuous heating to 500°C in vacuum for 250 h. In particular, this work reports the variation in the solar absorptance of TiB₂/Ti(B,N)/SiON/SiO₂ coating with different angles of incidence of the solar radiation. Extensive analysis using the TEM technique reveals the presence of oxide interlayers that act as diffusion barrier layers to enhance the thermal stability of the coating. Computational simulation using SCOUT software validates the measured reflectance spectrum of the developed multilayer coating. The minor changes in absorptance and emissivity after heat treatment in vacuum at 500°C, together with high solar absorptance over a broad angular variation, establish the potential application of TiB₂/Ti(B,N)/SiON/SiO₂ as a selective coating in concentrated solar power systems.     

Characterization of absorptivities to solar radiation for colored pigments in coatings

Colored pigments absorptivities to solar radiation have been characterized quantitatively by measuring the absorption coefficients of the colored pigments mixed in white titanium dioxide standard coating. The standard coating contains white TiO₂ with 17% pigment volume concentration (PVC). Dry white coating with more than 134 μm thickness is opaque and used as a dispersion medium for colored pigments. The reflectances of the coatings of white TiO₂ and three kinds of colored pigments (perylene black, toluidine red, and benzidine yellow) to solar radiation are measured by means of a UV-3100 recording spectrophotometer operating in the 250∼2500 nm spectral range. It is found that the plots of lg 1/R (R, reflectance of coating to solar radiation) againstV _coloredV_{Ti0 2} (volume ratio of the colored pigment to TiO₂ in coating) are straight lines of increasing slopes in the range ofV _coloredV_{Ti0 2} less than five percent. From the slopes of the straight lines, the absorption coefficients of colored pigments can be measured quantitatively. Beijing, 100029, China. Email: guohy@public.fhnet.cn.net.     

Study on silica coated chrome oxide green pigment and its performance

In this study, sodium silicate (Na₂SiO₃) was used as the precursor of SiO₂ to prepare Cr₂O₃/SiO₂ composite pigments. First, using cetyltrimethylammonium bromide to surface modification of the chromium oxide green pigment to make the surface of the particles positively charged. The negatively charged SiO₂ sol coats the surface of the pigment particles through electrostatic attraction. Then use HCl solution acid to precipitate SiO₂, and finally get Cr₂O₃/SiO₂ composite pigment. The structure of the modified pigment was analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), particle size distribution analysis, and X-ray diffraction (XRD) characterization. The influence of silica coating on the tinting strength, dispersibility of pigment in water, and hiding power of the chromium oxide green pigment were further investigated. The results demonstrate that SEM, TEM, and particle size analysis shows that this experimental method can obtain a good silica coating. When the coating quantity is 30%, the full coating of chromium oxide green by silica is achieved. According to the XRD analysis before and after the chromium oxide green coating, as the reaction temperature increases, the intensity of the SiO₂ diffraction peak becomes larger and the crystallization effect becomes better. In the test of pigment performance, it can be concluded that the coloring power, hiding power, and dispersibility of Cr₂O₃/SiO₂ composite pigments are better than those of uncoated chromium oxide green pigments.     

Sol-gel synthesized rare earth La3+ ions doped Zn2SiO4 phosphors for lighting applications

In this study, Zn_2-xLa_xSiO₄ (x = 0.00, 0.02, 0.04, and 0.06) materials with varying weight percentages of lanthanum (La) in zinc silicate (Zn₂SiO₄) were synthesized using the sol-gel process. The effect of La dopant on the structure, morphology, and optical characteristics of Zn₂SiO₄ was investigated through various analytical and spectroscopical techniques. According to PXRD measurements, La³⁺ ions were incorporated into the host materials of Zn₂SiO₄, considerably affecting their crystallinity. Irregular granular and pebble stone-like morphology was observed in the FESEM analysis. The optical energy bandgap of La-doped Zn₂SiO₄ materials decreased from 5.09 eV to 3.80 eV while increasing the La dopant into Zn₂SiO₄ host systems. The photoluminescence (PL) spectra and photoluminescence quantum yield (PLQY) confirmed the increase of luminescent peak intensity at 730 nm. A tri-exponential fitting technique was used to determine the luminescence decay lifetime of the significant emissions of La-doped Zn₂SiO₄, and the average lifetime was found to be 30.4 ns. Dosimetry could benefit significantly from the thermoluminescence investigation conducted for the La-doped Zn₂SiO₄ phosphor at a linear heating rate of 8 °C/s.     

Stable multilayer TiO<Subscript>2</Subscript>–SiO<Subscript>2</Subscript> coatings for antireflection applications

In this paper, multilayer TiO₂–SiO₂ containing polydimethylsiloxane (PDMS) coatings were produced by using sol-gel method. To further investigate, the effect of triton as a non-ionic surfactant on PDMS modified single and multilayer silica and titania coatings was studied. The results showed stability of optical triton containing coatings disappears with time due to this material improve the wetting properties of PDMS sols and helps to instability by water absorption. But without triton, antireflective multilayer coatings with high transmittance 98% and excellent durability were obtained by using PDMS as additive material. This coating can be used as well as in solar applications.     

Effect of Size-Dependent Thermal Instability on Synthesis of Zn<Subscript>2</Subscript> SiO<Subscript>4</Subscript>-SiO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> Core–Shell Nanotube Arrays and Their Cathodoluminescence Properties

Vertically aligned Zn₂SiO₄-SiO _x (x < 2) core–shell nanotube arrays consisting of Zn₂SiO₄-nanoparticle chains encapsulated into SiO _x nanotubes and SiO _x -coated Zn₂SiO₄ coaxial nanotubes were synthesized via one-step thermal annealing process using ZnO nanowire (ZNW) arrays as templates. The appearance of different nanotube morphologies was due to size-dependent thermal instability and specific melting of ZNWs. With an increase in ZNW diameter, the formation mechanism changed from decomposition of “etching” to Rayleigh instability and then to Kirkendall effect, consequently resulting in polycrystalline Zn₂SiO₄-SiO _x coaxial nanotubes, single-crystalline Zn₂SiO₄-nanoparticle-chain-embedded SiO _x nanotubes, and single-crystalline Zn₂SiO₄-SiO _x coaxial nanotubes. The difference in spatially resolved optical properties related to a particular morphology was efficiently documented by means of cathodoluminescence (CL) spectroscopy using a middle-ultraviolet emission at 310 nm from the Zn₂SiO₄ phase.     

Tuning the optical bandgap of multi-walled carbon nanotube-modified zinc silicate glass-ceramic composites

Novel glass-ceramic composites with optical bandgap tunability were synthesised. Zinc silicate powder (ZS) was mixed with multi-walled carbon nanotubes (MWCNTs) at various mass fractions (0, 1, 2, and 3 wt %), followed by argon sintering. X-ray diffraction (XRD) analysis revealed the structural change from an amorphous ZS phase to a crystalline willemite phase (Zn₂SiO₄) by adding MWCNTs, and the largest crystallite size was obtained for ZS with 2.0 wt% MWCNTs. Although the agglomeration of ZS and MWCNTs was observed by field emission scanning electron microscopy (FESEM), there was no chemical interaction between ZS and MWCNTs as confirmed by Fourier transform infrared spectroscopy (FTIR). MWCNTs enhanced the crystallisation, which led to the green emission of Zn₂SiO₄ blue-shifting from 572 nm to 557 nm. The narrowed optical bandgap of Zn₂SiO₄ was attributed to the MWCNT-induced exciton localised between the valence band and conduction band of Zn₂SiO₄. The bandgap tuning effect of MWCNTs potentially paved new ways to mass fabricate zinc silicate-based semiconductors with desirable optical bandgap energy E_g, which significantly benefits the sensor and laser-related industry.     

Visible-to-MIR broadband modulating electrochromic metal oxides-based coating for thermal management

The overheating/cooling of spacecraft solar cells under the contrastive temperature variation due to solar influence leads to severe consequences on both its performance and its long-term stability. Radiative thermal management by broadband optical modulating coating provides a versatile and effective solution for spatial environments. Here we design a visible-to-mid-infrared broadband modulating metal oxide-based electrochromic coating for spacecraft solar cell thermal management. Upon impedance matching between multilayered architecture and control of crystallinity of WO₃ with optimized morphology, the final coating successfully presents reversible transition from solar transmitter and thermal emitter to heat preserving coating with infrared (IR) stealth ability. The transmission spectrum of the coating in its bleached state fits the solar spectrum curve (0.3-1.2 μm) for photocurrent harvesting and it transmits up to 88% at 450 nm, at the solar radiation peak. The average mid-infrared (MIR) (2-16 μm) emissivity of the coating is 80%, with a tunability of 20% in average. The demonstrated capabilities of broadband modulating electrochromic coating are highly promising for solar cell thermoregulation in space or terrestrial environments and also for IR-stealth applications in the defense sector.     

Solution combustion of spinel CuMn2O4 ceramic pigments for thickness sensitive spectrally selective (TSSS) paint coatings

A series of spinel-type CuMn₂O₄ ceramic pigments were prepared by a facile and low-cost sol-gel solution combustion method and used as cost-effective materials to fabricate thickness sensitive spectrally selective (TSSS) paint coatings by a convenient spray-coating technique. The chemical component, crystalline morphology, and optical property of the copper manganese oxide ceramic pigment could be accurately controlled by altering the annealing temperature. X-ray diffraction (XRD) analysis confirmed that the ceramic pigments annealed at 500 °C for 1 h coincided well with the XRD patterns of crystalline CuMn₂O₄ in the JCPDS database, and there were segregated phases of CuO and Mn₂O₃. Furthermore, the pure spinel CuMn₂O₄ phase could be achieved at 900 °C for 1 h. The copper manganese oxide ceramic pigments could serve as an effective pigment for fabricating the TSSS paint coating, and the TSSS paint coatings based on ceramic pigments calcined at 900 °C showed solar absorptance of 0.895–0.905 and thermal emittance of 0.186–0.310. In addition, the accelerated thermal stability test revealed that the TSSS paint coating exhibited good thermal stability when it was exposed to air at a temperature of 300 °C for 300 h. Hence, the fabricated TSSS paint coating could be used as a solar absorber coating in the low-to-mid temperature domain.     

Effects of solvent-induced morphology evolution of Zn2GeO4 on photocatalytic activities of g-C3N4/Zn2GeO4 composites

Morphology modulation of photocatalyst has been demonstrated to be a crucial strategy for improving the catalytic performance in solar energy conversion system. Here we systematically investigated the influence of the solvent-dependent morphology evolution of Zn₂GeO₄ phase on the photocatalytic efficiency of the as-prepared g-C₃N₄/Zn₂GeO₄ composites. The morphologies of Zn₂GeO₄ were rationally tuned from flower-like nanosheets to length-controllable nanorods, and microclusters assembled from microrods through regulating the solution polarity of different organic solvents. Accordingly, the Zn₂GeO₄ sample prepared in ethylene glycol (EG) with long rod-like morphology and integrated with g-C₃N₄, abbreviated as g-C₃N₄/Zn₂GeO₄(1:1)-EG, exhibited the best visible-light absorption ability and the highest efficiency. The synergetic effect of the long rod-like Zn₂GeO₄ phase with many exposed (110) crystalline facets and g-C₃N₄ accelerates the separation and interface transportation of photoexcited charge carriers, as confirmed by photocurrent measurements. The MB degradation mechanism was also proposed to clarify the charge-transfer process and the improved photodegradation activity. This study offers an experimental basis for understanding the significance of morphology control on rational design of photocatalysts with improved performance.     

Synthesis of silica-supported ZnO pigments for thermal control coatings and analysis of their reflection model

A spacecraft in orbit undergoes extreme temperature cycling, space radiations, and other extreme conditions that can potentially raise the temperature of spacecraft to harmful levels. Hardware and sensitive detectors utilized in spacecrafts require that temperatures be maintained within specified ranges. Thermal control coatings (TCCs) help to maintain the thermal equilibrium of the spacecraft at a level acceptable for vital components. This is done by employing the diffused reflection of all effective ultraviolet (UV), visible (VIS), and near-IR (NIR) wavelengths of solar radiation and emitting the infrared (IR) energy. The most commonly used TCCs have utilized potassium silicate as the binder and ZnO as the pigment (Z-93), but absorption of UV light by ZnO pigment affects the ideal scheme of these TCCs. In the present study, silica-supported zinc oxide particles with different ZnO contents were synthesized as pigments for white thermal control coatings and the optimized one was selected based on the experimental determination of the optical properties of the prepared coatings. The results revealed that the optimized TCCs containing pigment with the zinc to silicon ratio of 1.91 had better reflection and emission properties in comparison with Z-93, due to the improvement in the refractive index and the dispersion quality of pigment. Then, the scattering properties (S) of the synthesized pigments and ZnO in TCC were investigated based on the reflectance data, according to the Kubelka–Munk analysis. The general trend in scattering coefficients for each formulation showed the same shape, such that with the increase in S values, the zinc to silicon ratio of pigments was raised too. Also, this trend revealed that scattering was more efficient at longer rather than shorter wavelengths. For Z-93, this trend was completely opposite. Also, S values for Z-93 in the wavelength range of 200–400 nm were around zero, while for the prepared coatings, this was not the case. Finally, the statistical nonlinear regression method was utilized to prepare a model for reflectance as a function of the zinc to silicon ratio of pigments and the wavelength of light.     

A multiple-scattering model analysis of zinc oxide pigment for spacecraft thermal control coatings

Space assets inhabit a harsh thermal environment in which the high intensity of direct solar radiation can potentially raise temperatures to harmful levels. Thermal management is obtained through the use of radiators coated with thermal control coatings (TCCs) that diffusely reflect the sun’s high energy visible (VIS) and near infrared (NIR) radiation, while emitting infrared (IR) energy as a method of radiatively cooling. The current state-of-the-art TCC system utilizes a potassium silicate binder and zinc oxide (ZnO) pigment to maintain solar reflectance over a long exposure time. We are investigating improvements to TCCs that will have greater initial performance and significantly better end-of-life properties. We have utilized modeling techniques based upon Mie scattering to determine the theoretical scattering efficiency limits of the currently used materials. An optimized TCC would attain maximum diffuse solar reflectance at a lower film thickness and reduce the pigment volume concentration (PVC) required. These factors would contribute to a reduction in overall weight and possibly extend the durability of the system to longer time scales. Our results of modeling ZnO pigment embedded in a matrix similar to that of potassium silicate under solar irradiance conditions indicate that a narrow particle size distribution centered at 0.35 μm would provide the highest overall scattering coefficients, ranging from 0.75 μm⁻¹ at 1000 nm to 5.0 μm⁻¹ at 380 nm wavelengths. These results indicated that a significant improvement, 2–10 times dependent upon wavelength, in the scattering efficiency of ZnO-based TCCs can be realized by utilizing an optimized particle size distribution rather than the currently used size distribution.     

Effective synthesis of green nano-sized ceramic pigments by co-doping Zn2+, Cr3+ and Sm3+ into the cobalt-aluminate

A green nano-sized ceramic pigment Co_0.6Zn_0.4Al_0.8Cr_1.2-xSm_xO₄ has been successfully prepared by doping ions Zn²⁺, Cr³⁺, and Sm³⁺ into the crystalline CoAl₂O₄ spinel and using the complex-gel method along with agar as complexing and combustion agent. The Infrared Spectroscopy, X-ray diffraction, Thermo-gravimeter, High resolution transmission electron microscopy, Automatic color reader, and UV Vis diffuse reflectance were applied to characterize the pigment power and its gel precursor. The results reveal that the introduction of Zn²⁺, Cr³⁺, and Sm³⁺ could change the occupation status of ions in the tetrahedral and octahedral framework of CoAl₂O₄ spinel, leading to the colorant variation of the blue cobalt pigment CoAl₂O₄, With increasing the content of Sm³⁺ ion, the reflection peak position of the pigments in visible spectrum appeared a red-shift, ie the color transition from blue green to yellow green, and the average reflectivity in the violet region decreased to 13.31%, and the band gap energy also changed from 3.47 to 3.20 eV. This illustrates the better UV absorption of this green pigment and can be used as UV shielding material. With the hydrochloric acid or sodium hydroxide solution treatment, this pigment was found to be durable in chemical stability.     

Co-doped willemite ceramic pigments: Technological behaviour,crystal structure and optical properties

Cobalt-doped willemite is a promising blue ceramic pigment, but some important aspects concerning crystal structure, optical properties and technological behaviour are still undisclosed. In order to get new insight on these features, willemite pigments (Zn_2?xCo_xSiO₄, 0 < x < 0.3) were synthesized by the ceramic route and characterized from the structural (XRPD with Rietveld refinement), optical (DRS and colorimetry), microstructural (SEM, STEM, TEM, EDX, EELS) and technological (simulation of the ceramic process) viewpoints. The incorporation of cobalt in the willemite lattice, taking preferentially place in the Zn1 tetrahedral site, induces an increase of unit-cell parameters, metal–oxygen distances, and inter-tetrahedral tilting. It causes shifting and enhanced splitting of spin-allowed bands of Co²⁺ in tetrahedral coordination, implying slight changes of crystal field strength Dq and Racah B parameter, but increasing spin-orbit coupling parameter λ. Willemite pigments impart deep blue hue to ceramic glazes and glassy coatings with a colouring performance better than commercial Co-bearing colorants in the 800–1200 °C range. Detailed SEM-TEM investigation and microanalysis proved that no diffusion phenomena occur at the pigment–glassy coating interface and that willemite pigments are chemically inert during firing at 1050 °C.     

Construction of Er-doped ZnO/SiO2 composites with enhanced antimicrobial properties and analysis of antibacterial mechanism

Herein, silica carrier was used as underlying structure to prepare composite material loaded with rare earth element Er and Zn. Rare earth elements can improve antimicrobial effects of ZnO due to their specific electronic structure. Er–ZnO/SiO₂ hybrid antibacterial material was prepared through sol-gel method and its structure and morphology were characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, inductively coupled plasma emission spectroscopy and Brunauer-Emmett-Teller measurements. E. coli and S. aureus were selected as model bacteria to assess antibacterial activity of prepared hybrid material by plate coating method. Er–ZnO/SiO₂ exhibited good antibacterial activity towards E. coli and S. aureus. Increase in Er³⁺ concentration from 0.12% to 1.10% led to increase in antibacterial performance followed by subsequent decrease. Improving effect of Er relied on the molar ratio of Er doped in ZnO/SiO₂ hybrid material. The optimal sample was found to be 0.60%Er–ZnO/SiO₂, with antibacterial rates of 93.71% and 70.46% against E. coli and S. aureus, respectively. Antibacterial mechanism was assessed by fluorescence detection of reactive oxygen species. In addition, flame atomic absorption spectrometry was used to measure the amount of released Zn²⁺. Results also showed that 0.60%Er–ZnO/SiO₂ hybrid material generated more reactive oxygen species, released more Zn²⁺ ions, and had the largest surface area, which improved its antibacterial rate. Thus, Er enhanced antibacterial properties of ZnO/SiO₂, providing these composite materials with great potential as antibacterial products.     

Radiation Resistance and Mechanical Stability of SiO2–BaO-Based Glass Coatings for Space Solar-Cell Panels

The influence of proton irradiation (energy, 18 MeV; beam current, 300 nA) with doses of 5 × 10¹⁴, 10¹⁵, and 5 × 10¹⁵ cm^–2 on samples of SiO₂–BaO-based glass coatings is investigated. The absorption, photoluminescence, and gamma luminescence spectra of the studied samples and their microhardness are measured. It is found that proton irradiation leads to a twofold increase in the microhardness. An insignificant increase in the optical absorption is revealed in the near-ultraviolet range (200–400 nm). This increase is accompanied by a decrease in the intensity of both light scattering in the wavelength range 400–900 nm and photoluminescence. The intensity of broadband gamma luminescence with a maximum at a wavelength of 500 nm increases with increasing proton irradiation dose. This means that excitonic radiative recombination impedes the formation of structural defects and their associated color centers. The combined effect of proton irradiation and solar electromagnetic radiation (gamma and visible light rays) accompanied by temperature changes in the range 80–470 K can provide an increase in the radiation resistance and mechanical stability of glass coatings used for solar-cell panels and their longer service life even under conditions of increased solar activity.     

Effect of heat treatment on photoluminescence behavior of Zn2SiO4:Mn phosphors

The thermal treatment in reducing atmospheres gives rise to the increase both in emission intensity and 10% decay time in Zn₂SiO₄:Mn phosphors. The present investigation aims to take account of such changes in association with the structural change. For this sake, X-ray absorption spectroscopy techniques such as XANES and EXAFS were conducted to the Zn₂SiO₄:Mn phosphors. The Zn₂SiO₄:Mn phosphors were fired in the air and then thermally treated in two different reducing atmospheres (hydrogen or carbon). The photoluminescent (PL) behavior was closely related to the X-ray absorption data. The XANES and EXAFS prove that the oxidation state (+2) remains identical regardless of whether or not the samples are treated, but that the Mn–O distance was reduced by the heat treatment. In order to give a plausible interpretation to the change in PL results, two possible suggestions are presented. Firstly, it is conceivable that the thermally activated diffusion process of manganese ions splits Mn–Mn pair during the heat treatment. Another possibility is that the thermal treatment annealed out some quenching site, which is related with defects and impurities. Such hypotheses can be rationalized systematically by considering the results from lifetime measurement, Debye–Waller factor calculation, and XANES pre-edge peaks.     

Developing the properties of new blue phosphors: TiO2-doped Zn2SiO4

2ZnO + SiO₂ + X mol% TiO₂ (Zn₂SiO₄-X-TiO₂, 1 ≤ X ≤ 3) and 2ZnO + SiO₂ + 3 mol% MnO₂ (Zn₂SiO₄-3-TiO₂) compositions were prepared using nanoscale ZnO, SiO₂, TiO₂, and MnO₂ particles. The mixing powders were calcined between 1000 °C and 1300 °C in a N₂ atmosphere. Zn₂SiO₄ was the only phase in the calcined Zn₂SiO₄-X-TiO₂ phosphors. We found that the photoluminescence (PL) properties of synthesized Zn₂SiO₄-X-TiO₂ phosphors revealed these to be blue rather than green. The effects of TiO₂ content and calcining temperature on the PL properties of Zn₂SiO₄-X-TiO₂ phosphors were rigorously investigated.     

Hybrid 1-D dielectric microcavity: Fabrication and spectroscopic assessment of glass-based sub-wavelength structures

Two different 1-D multilayer dielectric microcavities are presented, one activated by Er³⁺ ions fabricated by rf-sputtering and other one containing CdSe@Cd_0.5Zn_0.5S quantum dots obtained by a hybrid radio frequency-sputtering/solution deposition process. The rare-earth activated cavity is constituted by an Er³⁺ -doped SiO₂ active layer inserted between two Bragg reflectors consisting of 10 pairs of SiO₂/TiO₂ layers. Starting from the deposition procedure used for this cavity a fabrication protocol was defined with the aim to combine the high reproducibility allowed by the sputtering deposition for the fabrication of multilayers structures with the ability of fabricate films activated with highly luminescent quantum dots dispersed in polymeric matrix. In this case the cavity was constituted by poly-laurylmethacrylate host matrix containing CdSe@Cd_0.5Zn_0.5S quantum dots inserted between two Bragg reflectors consisting of 10 pairs of SiO₂/TiO₂ layers fabricated by rf-sputtering on SiO₂ substrate. The thicknesses of the films of the Bragg reflectors were tailored in order to reflect the visible radiation at around 650 nm. Transmittance spectra were employed to assess the optical features of the single Bragg gratings and whole samples. Luminescence measurements put in evidence that emissions strongly influenced by the presence of the cavities for both the samples.     

Optimization of potassium zinc phosphate anticorrosion pigment by Taguchi experimental design

The synthesis condition of potassium zinc phosphate pigment was optimized with respect to corrosion inhibition in extract solution and dispersion stability in an epoxy resin by application of Taguchi experimental design. Processing parameters, including calcinations time, quiescent time, mixing rate and KOH/ZnCl₂ mole ratio are selected as the influential parameters. Corrosion inhibition of the pigments in the extract solutions and dispersion stability in the epoxy resin were evaluated by electrochemical impedance spectroscopy (EIS) and turbidity measurement, respectively. The pigment synthesized under optimal condition was characterized by XRD, which showed formation of KZnPO₄ and KZn₂PO₄(HPO₄). Corrosion protection of the epoxy coating containing synthesized pigment at optimal condition was evaluated by salt spray and compared to the unpigmented epoxy coating. Salt spray results showed higher corrosion protection of the epoxy coating in the presence of potassium zinc phosphate, which could be attributed to lower diffusivity of the pigmented coating to Cl⁻ or formation of phosphate layer confirmed by SEM–EDX.