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Optical erbium oxide (Er 2 O 3) films were prepared by radio frequency (RF) magnetron sputtering to improve the infrared (IR) transmittance of chemical vapor deposition (CVD) diamond. This study aims to analyze the microstructure, composition and optical properties of Er 2 O 3 anti-reflection films at various oxygen/argon ratios. Atomic force microscopy (AFM) analysis was used to detect the surface morphology of chemical oxidation CVD diamond and Er 2 O 3 films. The surface roughness of Er 2 O 3 films decreased with an increase in the oxygen/argon ratio. The crystalline structure of Er 2 O 3 films was analyzed by using X-ray diffraction. Meanwhile, a gradual decrease was observed when the crystallite size and its strain were calculated. This was due to the transformation of partial phases from monoclinic to cubic structures. The chemical composition of Er 2 O 3 films was analyzed by X-ray photoelectron spectroscopy (XPS). The surface of Er 2 O 3 films underwent a transformation from the unstable structure of nonstoichiometric Er 2 O 3-x to the stable structure of Er 2 O 3 with an increase in the level of oxygen. Defect behavior was determined by transmission electron microscopy (TEM). Specifically, dislocation and twinning were observed at a high oxygen/argon ratio, which was mainly attributed to the competitive growth of polycrystalline Er 2 O 3 films. The optical constants of Ψ and △ were shifted to lower wavelengths with increase oxygen/argon ratio. The maximum transmittance of the Er 2 O 3 /diamond film was 79% in the long-wavelength infrared (LWTR) range of 8–12 μm at an oxygen/argon ratio of 1:35. This value was significantly higher than that of the high oxygen/argon ratio. The present study concludes that a low oxygen/argon ratio promotes the growth and IR transmittance of Er 2 O 3 films. [ABSTRACT FROM AUTHOR]

Graphite-based metal transition-layer substrates hold great potential for preparing large-area diamond films and achieving crack-free release. In this study, a five-inch crack-free free-standing diamond film was prepared on a graphite substrate with a sacrificial Mo/Ti double-layer transition layer using direct-current arc plasma jet chemical vapor deposition (DC jet CVD). The interfacial bonding and diffusion behavior between the diamond and the transition layers were investigated. The effect of abundant metal particles and elemental diffusion between layers on film adhesion and stress release are discussed and analyzed. The surface of Ti layer prepared by the multi-arc ion-plating contains numerous metal particles that provide a template for the fine-crystalline Mo layer. Metal particles are encapsulated and embedded in the diamond and act as anchors that ensure the stability of the substrate–diamond bond during high-temperature deposition. After deposition, those metal particles act as weak points and play crucial stress-release roles. Mutual elemental diffusion occurs between the Ti, Mo, and diamond layers. Ti penetrates the Mo layer to form a continuous 140-nm-thick thin layer during the initial deposition period, facilitating diamond nucleation. Carbon from the plasma and diamond diffuses into the metal transition layer. Thermal stress generated between the diamond and the graphite substrate is released by destroying the metal transition layer with high thermal expansion coefficient and low elastic modulus during cooling from the deposition temperature. Cracks rapidly propagate along the interface between destroyable transition layers and graphite substrate, which results in the liftoff of a fully crack-free diamond film. [Display omitted] [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction (OER) is critical in water splitting for green hydrogen gas production due to its sluggish kinetics; however, commercial OER catalysts commonly suffer from high cost, low catalytic activity and poor stability. Herein, we developed a C+ ion implantation method to modify single crystal diamond, and the resultant surface amorphous layer not only raised the active site number but also increased the content of the C=O group, thus significantly improving the OER activity. The C+ ion implanted high-temperature and high-pressure (C+-HTHP) and chemical vapor deposition (C+-CVD) diamonds both exhibit low OER overpotential with η 10 of 317 mV and 325 mV respectively, superior to those of HTHP diamond (360 mV), CVD diamond (395 mV) and RuO 2 (364 mV). The potentiostatic testing shows that the C+ implanted diamonds almost didn't undergo the rise of OER overpotential upon catalysis for more than 12 h at a current density of 10 mA cm−2, suggesting a high catalytic stability, owing to the strong bonding between single crystal diamond and amorphous carbon layer. For the first time, we utilized carbon ion implantation to prepare diamond-based high-performance OER catalyst, which broadens the understanding of carbon-based materials in OER catalysis. [ABSTRACT FROM AUTHOR]

Reducing the self-heating of SiC- and GaN/SiC-based high-powered devices by integrating diamond films offers promising performance enhancement of these devices. However, such a reduction strategy faces serious problems, such as diamond nucleation on SiC and stress accumulation greater than 10 GPa. In this work, a SiN x dielectric layer (∼50 nm) was coated onto the C polar face of a 4H–SiC wafer using microwave plasma chemical vapor deposition (MPCVD) to improve direct dense diamond nucleation and growth, significantly reduce the stress, and build Si–C(SiC)⋯Si⋯C(diamond) bond bridges. This SiN x thin layer, prepared by activating Si ions under Ar/N plasma during magnetron sputtering, gave rise to local Si 3 N 4 crystal features and a low effective work function (EWF) for promoting surface dipoles with electronegative carbon-containing groups. In the H plasma environment during diamond growth, the local Si 3 N 4 crystal was amorphized, and the N atoms escaped as a result of atomic H and the high temperature. At the same time, C atoms diffused into the SiN x and formed C–Si bonds (49.7% of the total C bonds) by replacing N–Si and Si–Si, thus increasing the direct nucleation density of the diamond grains. The diamond thin film grew rapidly and uniformly, with a grain size of approximately 2 μm in mixed orientation, and the stress of the 2-inch SiC-on-diamond wafer was extremely low (to ∼0.1–0.2 GPa). In comparison, partially connected diamond grains (>10 μm) on the bare SiC in the preferential (110) orientation resulted in a film with twin-grain features and significant stress, which was associated with the hexagonal lattice interface of 4H–SiC. These results are considered the material and surface/interface bases for actively controlling wafer fabrication and enhancing the heat dissipation of SiC and GaN/SiC electronics. [ABSTRACT FROM AUTHOR]

In this study, standard diamond bars were prepared using an ultra-thick diamond plate, and the bars had sizes consistent with the International Organization for Standardization (ISO) 14704:2016(E) three-point bending method for measuring the fracture strength. Ultra-thick diamond plate with dimensions of 125 mm (diameter) × 6.5 mm (thickness) were deposited using direct current arc plasma jet chemical vapour deposition. After cutting, grinding, and polishing, 12 diamond bars meeting the requirements of the ISO standard were prepared (36 mm × 4 mm × 3 mm) and tested for fracture strength using the cited ISO standard and elastic modulus using deflection measurements. The fracture strength of the ultra-thick diamond plate was found to be 580 ± 66 MPa. In addition, for comparison, the fracture strengths of standard ZnS, sapphire, and alumina were also analysed. Crucially, this is the first report of the fracture strength of standard-sized diamond plate. The effects of the defects and grain size on the crack formation and failure of the diamond film were analysed. The diamond's fracture strength was affected by the sample thickness, which caused the gradual accumulation of defects as this dimension increased, but not by its length and width. The elastic moduli of sapphire and alumina were compared. Overall, the measurement of the fracture strengths of ultra-thick diamond plate via the ISO standard is important for industrial applications. [ABSTRACT FROM AUTHOR]

• A self-consistent multi-physics coupling model including microwave electromagnetic field, plasma field and fluid heat transfer field is established. • CH 4 -H 2 plasma characteristics from 18 to 100 W∙cm−3. • Kinetics of CH 4 -H 2 plasma chemical reaction at high average power density. • High-rate growth of high-quality Φ 60 mm diamond films at high average power density of 100 W∙cm−3. Investigating the mechanism behind the high-efficiency deposition of high-quality diamond has always been a prominent topic in related research. This paper investigates the CH 4 -H 2 plasma characteristics and related chemical reaction kinetics in the average power density range of 18–100 W·cm−3, which is a typical range for large-area diamond film deposition. The number densities of H, CH 3 and C 2 H 2 increase linearly with the average power density. C 2 H 2 is the main hydrocarbon in the discharge, and CH 3 is the main single-carbon hydrocarbon. The number density and radial uniformity of CH 3 and C 2 H 2 increase with the average power density, which is necessary for the high rate and uniform deposition of diamond films. The plasma's optical emission spectra indicate an acceleration in the C 2 production rate at high power density. The diamond film deposition experiment demonstrates the efficacy of high average power density in achieving high-quality diamond deposition at a high growth rate. [ABSTRACT FROM AUTHOR]

A piece of diamond film (Ø 125 mm) was polished based on prefabricated stress. The diamond film was glued to a metal workpiece at high temperatures. The difference in the thermal expansion coefficients between the diamond film and the workpiece was exploited to prefabricate stress in the middle of the two materials. This prefabricated stress had a compressive effect on the diamond film, offset the stress generated in the grinding and polishing process, and prevented the diamond film from cracking. The feasibility of the prestressing method was verified by a combination of experiments and finite element simulations. The prestressing method was used to bond the diamond film to a 10 mm-thick brass fixture at 20, 50, 70, and 90 °C. It was found that when the temperature of the bonded diamond film reached 90 °C, the increase in the prefabricated stress was −410.71 MPa. The finite element simulation results were found to be consistent with the experimental data. The diamond film was cooled down to room temperature after bonding at high temperatures to simulate the prefabricated stress generation process. The diamond film with the prefabricated stress was again heated to the bonding temperature to simulate the stress change caused by the frictional heat generated during the polishing process. The stress of the bonded sample increased when it was cooled down to room temperature. The stress on the diamond surface became smaller during the polishing process, and the stress almost disappeared with the rise in bonding temperature, verifying the viability of the prestressing method. [Display omitted] • Prestressing method to polish a large-sized diamond film was proposed. • Diamond film was bonded to the metal fixture at high temperature and cooled. • The prefabricate stress was measured and simulated. • A Ø125 mm diamond film was successfully polished using this idea. [ABSTRACT FROM AUTHOR]

Deposition of a consistent diamond coating on intricate surfaces has historically posed a difficulty. This article presents the advancement in research on depositing a uniform diamond coating on three-dimensional (3D) silicon spheres, utilizing a faraday cage within a microwave plasma chemical vapor deposition (MPCVD) reactor. A self-consistent three-dimensional multi-physics field model has been established for simulating the microwave electric field and plasma inside a reactor with or without a faraday cage. Results indicate the cage effectively reduces the discharge at the top of the silicon sphere and improves uniformity of the distribution of the microwave electric field and plasma electron density on the sphere's surface. MPCVD trials have demonstrated that a powerful discharge takes place at the apex of the silicon sphere resulting in an excessive thermal gradient if the cage is not added. The apex of the silicon sphere is covered with a blend of diamond and graphite phases. Due to the excessive internal stress of the coating, approximately 50 % of the samples experience coating detachment. After the addition of the cage, the strong discharge is transferred to the top of the cage, effectively suppressing the microwave electric field and plasma inside the cage. Improved quality, reduced internal stress, and enhanced uniformity of the polycrystalline diamond coating are achievable on the silicon spheres within the cage. Moreover, this technique offers a novel approach to coat diamond on complex 3D geometries. [Display omitted] • Three-dimensional multi-physics modeling verifies that faraday cage suppresses microwave electric field and plasma. • The Faraday cage improves the uniformity of the distribution of microwave electric fields and plasma in the internal space. • Uniform, high crystal quality, low stress diamond coating. [ABSTRACT FROM AUTHOR]

The direct-current arc plasma jet method is advantageous for the rapid deposition of large-area self-supporting diamond films. However, dark defects tend to be generated during the growth process, significantly affecting the performance of the diamond. In this study, we use the direct-current arc plasma jet method to prepare transparent and translucent samples. Subsequently, we compare their optical, thermal, and mechanical properties and analyze the differences in their performances via microstructure and defect analyses. The results indicate that the transparent diamond samples exhibit excellent optical and thermal properties, with a transmittance of 68.4 % at a wavelength of 10.6 μm and a thermal conductivity similar to that of type-IIa single crystal diamond (i.e. 2002 W/(m·K)). Meanwhile, the translucent diamond exhibits outstanding mechanical properties, with a fracture strength of 984 MPa. Characterization results based on electron backscatter diffraction and X-ray computed tomography suggest that a preferred orientation along the (220) planes is conducive to the densification growth of the samples, thereby enhancing their optical and thermal properties. However, the generation of numerous twins results in interlocking between grains, which improves sample's mechanical properties but introduces porosity and impurities, thus deteriorating its optical and thermal performance. [Display omitted] • Optical and thermal diamond films were deposited by DC-arc plasma jet CVD with growth rates >6 μm/h. • Strong (220) texture and numerous twins can improve optical transmittance and fracture strength, respectively. • X-ray CT was used to reveal defects distribution and content within diamond samples. [ABSTRACT FROM AUTHOR]

Electronic and mechanical properties, and their biocompatibility, make diamond-based materials promising biomedical applications. The cost required to produce high quality single crystalline diamond films is still a hurdle to prevent them from commercial applications, but the emergence of polycrystalline diamond (PCD) films grown by chemical vapour deposition (CVD) method has provided an affordable strategy. PCD films grown on silicon wafer have been used throughout and were fully characterised by SEM, XPS, Raman spectroscopy and FTIR. The samples contain nearly pure carbon, with impurities originated from the CVD growth and the silicon etching process. Raman spectroscopy revealed it contained tetrahedral amorphous carbon with small tensile stress. The sp2 carbon content, comprised between 16.1 and 18.8%, is attributed to the diamond grain boundaries and iron-catalysed graphitisation. Antibacterial properties of PCD films were performed with two model bacteria, i.e. Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) using direct contact and shaking flask methods. The samples showed strong bacteriostatic properties against S. aureus and E. coli with the direct contact method and no influence on planktonic bacterial growth. These results suggest that the bacteriostatic mechanism of PCD films is linked to their surface functional groups (carbon radicals and –NH 2 and –COOH groups) and that no diffusible molecules or components were involved. [ABSTRACT FROM AUTHOR]

Lift-off is a promising method to prepare thin, high-finish, and freestanding large-area single crystal and polycrystalline diamonds. However, accurate control of the damage layer characteristic to achieve both stress release and lift-off process is difficult. In this work, high-energy C+ was implanted in single crystal diamond and polycrystalline diamond to create subsurface damage. The defect behavior and structural transformation of the ion implantation and annealing process were investigated. The homoepitaxial growth was subsequently carried out and the epitaxial layer was lifted off from the substrate by selectively etching the damaged layer. The results show that the cap layer and the substrate (below the damage layer) keep the sp3 carbon structure before and after annealing, which is confirmed by the atomic-scale electron energy loss spectroscopy (EELS). The high-resolution transmission electron microscopy (HRTEM) images show that after annealing at 1000 °C for 1 h, the damaged layer was transformed from amorphous carbon to a mixture of graphite and amorphous carbon, providing the damaged layer that could be removed by electrochemical solution. Meanwhile, the distorted diamond area was changed to a sharp interface, which ensures the low roughness of the substrate surface after the lift-off process. After etching for 30 h, a freestanding polycrystalline diamond film with a thickness of 100 μm and a surface roughness of 1.68 nm was obtained. The roughness of the lift-off substrate surface is 1.10 nm, indicating the epitaxial growth can be repeated directly without polishing. [Display omitted] • The defect behavior and structural transformation of the high-energy C+ implanted diamonds were investigated. • The stress state of the diamonds before and after ion implantation and after lift-off process were evaluated. • A 100 μm-thick freestanding polycrystalline diamond film with a surface roughness of 1.68 nm was successful obtained. [ABSTRACT FROM AUTHOR]

[Display omitted] • The La-doped Er 2 O 3 anti-reflection films was prepared by the power of magnetron sputtering. • The compound of La 2 O 3 formed along the grain boundary of the columnar crystal structure of the polycrystalline film. • The highest hardness and yield strength of the La-doped Er 2 O 3 film was two times higher than that of pure Er 2 O 3 film. • The transmittance of the La-doped Er 2 O 3 anti-reflection films only decreased 1% after erosion. The composition and microstructure consisting of anti-reflection films was obtained by the power of magnetron sputtering. X-ray photoelectron spectroscopy (XPS) and High-resolution transmission electron microscopy (HRTEM) provided evidence to support that the doping La element exists as oxide in the grain boundaries of the matrix Er 2 O 3 films. The undoped and La-doped Er 2 O 3 films show a columnar crystal structure of the main cubic (2 2 2) plane. Twinning and a large number of dislocations show up in the undoped Er 2 O 3 films due to the competitive growth of the columnar crystal. In addition, the La-doped Er 2 O 3 films show a lower roughness (RMS) value in comparison with undoped Er 2 O 3 films. The grain size of columnar crystals decreases significantly with increasing La concentration in the La-doped Er 2 O 3 films. The fine grains resulted in the La-doped Er 2 O 3 films developing high mechanical and impact resistance properties, with an increase in hardness from 12.6 ± 2.1 GPa to 26.1 ± 3.4 GPa and the eroding area rate decreasing from 38.9 % to 1.9 %. Moreover, the La-doped Er 2 O 3 anti-reflection films on the chemical vapor deposition (CVD) diamond substrate maintained 74 % transmittance in the long-wavelength infrared range of 8–12 μm after sand eroding. [ABSTRACT FROM AUTHOR]

In this study, the effect of defects on fracture toughness in different directions was investigated. Two diamond films with a diameter of 122 mm and as-deposited thicknesses of 2.2 and 1.5 mm, respectively, were deposited by DC arc plasma jet chemical vapor deposition. To accurately obtain the fracture toughness, the films were ground and polished to 1.6 and 0.8 mm, respectively. The results indicate that many defects, including pores, are introduced into the films during the growth process, particularly on the side close to the growth surface in thicker film. The size of pores reaches micrometres, which affects the fracture toughness under loading in different directions. Due to the minimum grain size, both films exhibit a maximum toughness of 8.2 and 10.0 MPa·m1/2, respectively, with growth-surface cracks. For the thinner sample, the maximum value is followed by that of the edge-surface cracks. As the grain size of the edge surface falls between that of the growth surface and that of the nucleation surface, the results indicate that fracture toughness is affected by grain size. However, the number of pores near the growth side increases when the thickness exceeds 0.8 mm. Pores reduce the toughness, resulting in the minimum fracture toughness (6 MPa·m1/2) of the thicker diamond film with edge-surface laser cracks. The sample with an edge-surface sharp pre-crack has a similar fracture toughness of 5.6 MPa·m1/2. This study provides guidance for selecting the applied load direction. • Two thick diamond films with thicknesses 2.18 and 1.48 mm were deposited. • Fracture toughnesses of the diamond films in three directions were investigated. • Numerous pores were formed in the diamond films during orientation growth. • Due to the effect of pores, the toughness values among three directions differ. [ABSTRACT FROM AUTHOR]

Surface etching of single-crystal diamond (SCD) in hydrogen plasma plays a decisive role for high-quality homoepitaxy and surface conduction of diamond. The complexity of surface/subsurface condition such as defects would give rise to the distinct morphology features and even further result in the unpredictable properties. Correspondingly, the evolutionary relationship between the morphology and electrical properties of mechanically polished SCDs which have typical cleavage damage in microns depth after hydrogen plasma treatment still needs to be further completed. In this work, the chemical vapor deposited (CVD) SCDs with uniform polishing-caused subsurface cleavage were immersed in microwave hydrogen plasma for variable duration. Time-dependent morphological evolution, multi-mode etched pits (EPs) (resulting from local defects/cracks and dislocations) and associated etching mechanism were comprehensively studied. At the early stage of plasma treatment before 60 min, owing to the obvious surface roughing generated by preferential etching (with the rate of >400 nm/h) of severe mechanically damaged regions, the hole mobility was significantly deteriorated, also accompanying with the apparent drop of sheet concentration. Concurrently, the deposited surface sp 2 amorphous carbon (a -C) nanodots on diamond surface and non- sp 3 hydrogen bonds reconstruction, which arising from defect-etching produced local abundant carbon-containing radicals or possible exfoliation generated by hydrogen penetration of massive defective regions, also would play an adverse role for the conduction associated with (100) C–H surface. However, the surface roughness was reduced from the maximum 13.2 nm–4.2 nm by prolonging etching, resulting from the smoothing effect of small-angle crystal misorientation on waved height difference related to the uniform (111) cleavage and the removal of dense irregular EPs associated with polishing-induced local defects as well as the vanishing of surface a -C nanodots. In this case, the improvement of surface electrical properties together with the negative correlation of the mobility and sheet concentration were appeared by the gradual formation of (100) diamond surface and the building of uniform (100) C–H bonds. • CVD SCDs with typical subsurface damages(defects) were treated in pure hydrogen plasma. • Morphology evolution associated with polishing defects was time-dependently presented. • Surface sp2 nanodots deposition from defect-etching and CH reconstruction would affect electrical properties. [ABSTRACT FROM AUTHOR]

Diamond has attracted increasing attention because it has high thermal conductive. Here, a freestanding diamond thermal conductive film with a diameter of about 7 in. and an average thickness of 1.54 mm was prepared by DC arc plasma jet CVD with multi-stage magnetic fields. Specifically, the thickness uniformity was ensured by adding the magnetic field during the deposition of the freestanding diamond film. The morphology, structure and thermal conductivity of the diamond film were studied. The results showed that the expansion area of the DC arc plasma approached the surface of the substrate increasing duo to add the bottom magnetic field. Structural characterization revealed that the grain of the diamond film in the arc main were coarse, affected by the shape of DC arc plasma, while in the arc center and edge were fine. The main orientation of polycrystalline structure of the diamond film was the crystalline plane of (220). The Raman peaks of diamond film in different areas moved to a higher wavelength, indicating the existence of compressive stress inside the diamond film. The coarse columnar grain and a few grain boundaries were in the arc main. Therefore, the average value of the thermal conductivity (k ⊥) of diamond film measured in the arc main was 1728.9 ± 4.9 W/(m·k). Meanwhile, the thermal conductivity of the arc center and edge area was lower than that of the arc main. [Display omitted] • A freestanding diamond thermal conductive film with a diameter of about 7 in. was prepared. • DC arc plasma jet CVD with multi-stage magnetic fields was adopted. • The average value of the thermal conductivity (k ⊥) of diamond film measured in the arc main was 1728.9 ± 4.9 W/(m·k). [ABSTRACT FROM AUTHOR]

A plasma arc generator was used to heat treat the free-standing CVD diamond films at 1450–1900 °C. An Arrhenius curve was fit according to trends in the measured Raman peak intensity ratio of diamond to graphite as a function of heat treatment temperature, and the curve was extrapolated linearly. It was found that the extrapolation lines intersected at the Debye temperature, Θ D = 2021 K. By comparing the activation energies of diamond graphitization in literature and from different measurement modes in our study, it was found that the graphitization mechanisms were different on both sides of Debye temperature due to differences in the excited lattice vibration modes. When the heat treatment temperature was just below the Debye temperature, the graphitization process was promoted by generating vacancies or the breaking of single C C bonds, and the apparent activation energy was 366 ± 60 kJ·mol−1. When the heat treatment temperature was above the Debye temperature, the graphitization process was promoted by the simultaneous breaking of multiple C C bonds, and the apparent activation energy was 887 ± 141 kJ·mol−1. In combination with the morphology changes on the surface of the CVD diamond film after high temperature heat treatment, the mechanism of the micro-cyclic phase transition on the surface of the diamond film at temperatures lower than Debye temperature was summarized as follows. First, C C bonds on the diamond surface were activated and broken at high temperatures, and some diamond carbon atoms dissociated from solid phase sites to the gas phase by forming hydrocarbon free radicals. Then, the carbon atoms from these hydrocarbons entered the graphite lattice step by step to complete the spontaneous deposition of sp2 clusters. [Display omitted] • The morphological changes of diamond surface dependent on temperature and hydrogen plasma environment were observed. • Taking the Debye temperature as a critical point, the graphitization activation energy exhibits a significant difference. • The graphitization mechanism of CVD diamond surface was proposed based on the kinetics analysis. [ABSTRACT FROM AUTHOR]

To improve the transmittance of chemical vapor deposition (CVD) diamond, erbium(III) oxide (Er 2 O 3) antireflective films were deposited on CVD diamond substrates by radio frequency (RF) magnetron sputtering. Effects of deposition temperature on structure, chemical composition and properties of the samples were investigated. A strong correlation was observed between the deposition temperature and crystalline structure evolution of the Er 2 O 3 antireflective films. With rising deposition temperature, the deposition rate, grain size and surface roughness of the Er 2 O 3 antireflective films increased. Changes of composition and chemical bonding of the films were analyzed. Results showed that the amount of bonding between Er and O atoms surface as the temperature increased. The films were structured by amorphous, monoclinic and cubic phase, with preferential orientations of C-Er 2 O 3 {222} at deposition temperature increased to 400 °C. A thickness of 10 nm transition layer was observed between the Er 2 O 3 antireflective films and the CVD diamond substrates by transmission electron microscopy (TEM). Moreover, the transition layer feature primarily consisted of Er, O and C. The hardness and modulus of Er 2 O 3 antireflective films were increased for higher deposition temperature, which positively affects the IR transmittance and adhesion strength of the Er 2 O 3 antireflective films on CVD diamond substrates. • The maximum transmittance of Er 2 O 3 /diamond sample was 80% in 7–11 μm range. • Texturization of Er 2 O 3 film interface was studied by HRTEM. • The higher deposition temperature favors crystallization of Er 2 O 3 film. • This study meets the requirements of windows for infrared (IR) imaging systems coating in the LWIR range. [ABSTRACT FROM AUTHOR]