Diffuse Streaks Research Articles

Formation of Stacking Fault Tetrahedra and Diffuse Streaks along 〈111〉 in the Equiatomic Cr-Co-Ni Medium-Entropy Alloy

Formation of Stacking Fault Tetrahedra and Diffuse Streaks along 〈111〉 in the Equiatomic Cr-Co-Ni Medium-Entropy Alloy

Contrasting irradiation behavior of dual phases in Ti-6Al-4V alloy at low-temperature due to ω-phase precursors in β-phase matrix

Aiming to simulate the radiation damage effect on a dual α+β phase Ti-6Al-4V alloy utilized as high-intensity accelerator beam window material, a series of irradiation experiments were conducted with a 2.8 MeV-Fe2+ ion beam in several dpa regions at room temperature. The nano-indentation hardness increased steeply at 1 dpa and unchanged up to 10 dpa, due to the saturation of defect clusters and tangled dislocations in the dominant α-phase matrix with a size of 2–3 nm and a density of about 1×1023 m−3. In contrast in the intergranular β-phase, larger loops of 20–30 nm diameter were observed with much less density of about 5×1020 m−3. The diffraction pattern showed rectilinear diffuse streaks between the β-phase reflections, corresponding to the ω-phase precursor, without dose dependency in its intensity. FFT/I-FFT analysis of the HREM revealed a sub-nanometer-sized lattice disorder with local fluctuations, not discrete but continuous, and homogeneously distributed within the matrix β-phase stably against the irradiation. The significantly low dislocation density and the absence of phase transformation in the β-phase matrix could be attributed either to the strong sink effect expected for this distinctive sub-nanometer-sized homogeneous lattice disorder or to the anomalous point defect recombination induced by the high mobility of vacancies, both of which are originated from the metastable ω-phase precursors specifically formed in the β(BCC) phase of group-4 transition metals.

Nb<sub>0.8</sub>CoSb ordering transformation caused by <i>in situ</i> heating-induced Nb diffusion

<sec>This study focuses on the investigation of Nb<sub>0.8</sub>CoSb half-Heusler alloy covered with Nb films. By employing <i>in-situ</i> heating transmission electron microscopy (TEM) technique, diffusion of Nb is observed at high temperature, showing the ordering transformation from Nb<sub>0.8</sub>CoSb to Nb<sub>0.8+δ</sub>CoSb. Through observations of high-angle annular dark-field (HAADF) images and selected-area electron diffraction (SAED) patterns, it is found that under elevated temperatures, the diffuse streaks representing short-range disorder in Nb<sub>0.8</sub>CoSb sample transform into superlattice diffraction spots representing long-range order. The modulation wave vector of this superstructure is determined to be <inline-formula><tex-math id="M3">\begin{document}$ q={1}/{3}({a}^{*}+{b}^{*}-{c}^{*}) $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20240325_M3.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20240325_M3.png"/></alternatives></inline-formula>. This structural evolution primarily arises from the diffusion of Nb atoms from the Nb film into the Nb<sub>0.8</sub>CoSb sample at high temperature, leading to compositional changes in Sb and Nb.</sec><sec>Further comparative analysis reveals significant differences between <i>in-situ</i> synthesized Nb<sub>0.8+δ</sub>CoSb samples and <i>ex-situ</i> synthesized Nb<sub>0.84</sub>CoSb samples despite both exhibiting superstructures. In the <i>ex-situ</i> synthesized Nb<sub>0.84</sub>CoSb, the modulation wave vector of the superstructure is <inline-formula><tex-math id="M4">\begin{document}$ q={1}/{3}({2a}^{*}-2{c}^{*}) $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20240325_M4.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20240325_M4.png"/></alternatives></inline-formula>, which is mainly attributed to Nb compositional variations. Moreover, the superstructure in Nb<sub>0.84</sub>CoSb sample can remain stable from room temperature to high temperature, whereas in Nb<sub>0.8+δ</sub>CoSb samples, it only exists at elevated temperatures and gradually weakens as the temperature decreases, suggesting that it may be a metastable structure between Nb<sub>0.8</sub>CoSb and Nb<sub>0.84</sub>CoSb.</sec><sec>This study reveals the diversity of superstructures induced by compositional variations and the complexity of structural phase transitions in half-Heusler alloys, enriching the understanding of these materials and providing important guidance for the design and functional control of phase-change materials.</sec>

Synthesis, crystal structure, and photoluminescence of new strontium barium nitrido-alumino-silicate phosphor, Sr27.9Ba22.8Al61.4Si174.6N328.4:Eu2+

Single crystals of a new nitrido-alumino-silicate containing both Sr and Ba, Sr27.9Ba22.8Al61.4Si174.6N328.4:Eu2+, were synthesized by heating a binary-nitride powder mixture at 2030 °C under a N2 gas pressure of 0.85 MPa for 4 h. The fundamental X-ray diffraction spots were indexed using orthorhombic cell parameters (a = 19.0272(5) Å, b = 40.4608(10) Å, c = 9.8641(3) Å), and diffuse streaks were observed between these spots. The crystal structure was analyzed using a statistical average structure model with space group Amm2. The (Al/Si)N4 tetrahedra share vertex and edge N atoms to form a three-dimensional network structure. Sr, Ba, and Eu atoms are distributed in the spaces within the network. Single crystals of Sr27.9Ba22.8Al61.4Si174.6N328.4:Eu2+ excited by light with a wavelength of 400 nm emitted yellow–orange light and showed a broad emission spectrum with a peak at 684 nm and a peak full-width at half-maximum of 239 nm. The maximum emission intensity at 200 °C was 74% of that at 25 °C.

Evolutions of the microstructures and mechanical properties of TC18 titanium alloy processed by hot-rolling in β single-phase region

In this study, hot rolling treatment followed by water quenching was conducted on a TC18 titanium alloy in β single-phase region with varying reductions. Experimental evidences from X-ray diffraction and transmission electron microscopy indicate the formation of α phase, induced by sufficient stress and assisted by ω phase. In addition, the existence of α" phase and diffuse streaks were also observed during the hot working processing. Furthermore, dynamic recrystallization (DRX) including continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) was proved to exist in the hot rolling process. During the whole DRX process, with increasing the deformation degree, recrystallized grains nucleated preferentially at high-energy areas such as grain boundaries and shear bands, then accumulated and grew until achieving a complete recrystallization state. It should be noted that DDRX mainly occurred at the grain boundaries, while CDRX grains nucleated within the shear bands. The elongation gradually decreased and tensile strength gradually increased with the increment of the deformation degree.

Analysis of diffuse scattering in electron diffraction data for the crystal structure determination of Pigment Orange 13, C32H24Cl2N8O2.

The crystallographic study of two polymorphs of the industrial pyrazolone Pigment Orange 13 (P.O.13) is reported. The crystal structure of the β phase was determined using single-crystal X-ray analysis of a tiny needle. The α phase was investigated using three-dimensional electron diffraction. The electron diffraction data contain sharp Bragg reflections and strong diffuse streaks, associated with severe stacking disorder. The structure was solved by careful analysis of the diffuse scattering, and similarities of the unit-cell parameters with the β phase. The structure solution is described in detail and this provides a didactic example of solving molecular crystal structures in the presence of diffuse scattering. Several structural models were constructed and optimized by lattice-energy minimization with dispersion-corrected DFT. A four-layer model was found, which matches the electron diffraction data, including the diffuse scattering, and agrees with X-ray powder data. Additionally, five further phases of P.O.13 are described.

Synthesis, Characterization and ADME Prediction Study of Heterocyclic Moieties-linked Indole Derivatives as Potential Antimicrobial Agents

Background: Heterocyclic compounds are vital for research due to their diverse pharmacological profiles. They are key structural components of many of the potent antimicrobial drugs available on the market today but still facing the problem of drug resistance by microbes. Indole and its derivatives display versatile pharmacological activities, such as analgesic, antimicrobial, antidepressant, antidiabetic, anti-convulsant, antihelmintic, and anti-inflammatory. Objective: Indole ring was linked to other key heterocyclic moieties, such as morpholine, imidazole, piperidine, and piperazine at the active 3rd position by Schotten-Baumann reaction, and further evaluated against Gram-positive and Gram-negative bacteria with the hope to develop potent antimicrobial agents. Method: Synthesis of derivatives was performed under appropriate conditions and characterized by IR, NMR (1H and 13C), and CHN elemental analysis. Further, in vitro assays were used to evaluate their antimicrobial activity by agar diffusion and agar streak dilution method against Bacillus subtilis (ATCC 6633) and Escherichia coli (ATCC 25922). ADME properties were also calculated using the Swiss ADME online program. Results: Compounds 4b, 4f, 4i, 4k showed maximum potency in both in vitro assays calculated as the zone of inhibition (17±0.5 mm-22±0.25 mm) and minimum inhibitory concentration (MIC= 6.25-25 μg/ml)) comparable to standard drugs ciprofloxacin and ampicillin. ADME results showed zero violation of the Lipinski’s rule. Conclusion: A great deal of work has been done on the synthesis and evaluation of indole derivatives to explore their antimicrobial effect. These findings may lead to the design and development of more effective antimicrobial drug candidates.

Antimicrobial Effects of Different Synbiotic Compounds against Pathogenic Bacteria Isolated from Beef, Mutton, and Chicken.

Today, there has been a growing interest in synbiotic usage in the food industry to solve the problems related to food contaminations. The present study aimed to evaluate the antibacterial effects of nine symbiotic compounds on bacteria isolated from different meat types. Pathogenic bacteria were isolated from 60 different meat samples. Then, the antibacterial effects of nine synbiotic components were assessed against isolated bacteria using well diffusion and radial streak methods. In addition, minimum inhibitory and minimum bactericidal concentrations of each synbiotic formulation were determined. The highest antibacterial activity against Listeria monocytogenes and Staphylococcus aureus was for synbiotic compounds consisting of Streptococcus salivarius, raffinose, inulin, and trehalose, respectively. Furthermore, the highest antibacterial efficacies against Escherichia coli and Salmonella were for synbiotic formulations consisting of Bacillus cereus and inulin, raffinose, and trehalose, respectively. In conclusion, synbiotic formulations containing S. salivarius and B. cereus may be an alternative approach to preventing food-borne pathogens.

Band energy diagrams of n-GaInP/n-AlInP(100) surfaces and heterointerfaces studied by X-ray photoelectron spectroscopy

Lattice matched n-type AlInP(100) charge selective contacts are commonly grown on n-p GaInP(100) top absorbers in high-efficiency III–V multijunction solar or photoelectrochemical cells. The cell performance can be greatly limited by the electron selectivity and valance band offset at this heterointerface. Understanding of the atomic and electronic properties of the GaInP/AlInP heterointerface is crucial for the reduction of photocurrent losses in III–V multijunction devices. In our paper, we investigated chemical composition and electronic properties of n-GaInP/n-AlInP heterostructures by X-ray photoelectron spectroscopy (XPS). To mimic an in-situ interface experiment with in-situ stepwise deposition of the contact material, 1 nm –50 nm thick n-AlInP(100) epitaxial layers were grown on n-GaInP(100) buffer layer on n-GaAs(100) substrates by metal organic vapor phase epitaxy. We observed (2 × 2)/c(4 × 2) low-energy electron diffraction patterns with characteristic diffuse streaks along the [011¯] direction due to PP dimers on both AlInP(100) and GaInP(100) as-prepared surfaces. Atomic composition analysis confirmed P-rich termination on both surfaces. Angle-resolved XPS measurements revealed a surface core level shift of 0.9 eV in P 2p peaks and the absence of interface core level shifts. We assigned the surface chemical shift in the P 2p spectrum to PP bonds on a surface. We found an upward surface band bending on the (2 × 2)/c(4 × 2) surfaces most probably caused by localized mid-gap electronic states. Pinning of the Fermi level by localized electronic states remained in n-GaInP/n-AlInP heterostructures. A valence band offset of 0.2 eV was derived by XPS and band alignment diagram models for the n-n junctions were suggested.

Crystal structure of the second extracellular domain of human tetraspanin CD9: twinning and diffuse scattering.

Remarkable features are reported in the diffraction pattern produced by a crystal of the second extracellular domain of tetraspanin CD9 (deemed CD9EC2), the structure of which has been described previously [Oosterheert et al. (2020 ▸), Life Sci. Alliance, 3, e202000883]. CD9EC2 crystallized in space group P1 and was twinned. Two types of diffuse streaks are observed. The stronger diffuse streaks are related to the twinning and occur in the direction perpendicular to the twinning interface. It is concluded that the twin domains scatter coherently as both Bragg reflections and diffuse streaks are seen. The weaker streaks along c* are unrelated to the twinning but are caused by intermittent layers of non-crystallographic symmetry related molecules. It is envisaged that the raw diffraction images could be very useful for methods developers trying to remove the diffuse scattering to extract accurate Bragg intensities or using it to model the effect of packing disorder on the molecular structure.

Synthesis, crystal structure, and photoluminescence of the new nitridoboroaluminosilicate phosphor (Sr0.93Eu0.07)11B2(Al0.275Si0.725)40N59

Single crystals of a new nitride, (Sr0.93Eu0.07)11B2(Al0.275Si0.725)40N59, were synthesized by heating a mixture of binary nitride powders at 2030 ​°C under nitrogen gas at 0.85 ​MPa. The fundamental X-ray diffraction reflections from a single crystal were indexed with the monoclinic cell parameters a ​= ​5.6836(4) Å, b ​= ​46.772(3) Å, c ​= ​5.6845(4) Å, and β = 118.028(2)° and diffuse streaks were observed between the reflections. The crystal structure was analyzed based on a statistical average structural model with space group Cm. The structure was determined to comprise (Al/Si)N4 tetrahedra and BN3 planar triangles forming a three-dimensional framework by sharing nitrogen atoms with Sr/Eu atoms located in the cage portions of the framework. Stacking faults in the b-axis direction and disordered atomic arrangements along the [1 0 1] direction on the a-c plane were observed by scanning transmission electron microscopy. These single crystal grains were found to emit red light when irradiated with near ultraviolet or blue light, with a maximum emission wavelength of 616 ​nm and a full width at half-maximum value of 106 ​nm in response to 450 ​nm light.

Application of a binary mixture of bio-extract on organic cotton fabric

Rosmarinus officinalis and Psidium guajava plant leaves are having rich sources of natural nutrients and phytochemical compounds. These phytochemical compounds inhibit the growth of microorganisms present in fewer animals and the human body. In this study, wound healing property was developed on organic cotton fabric using an equal ratio of Rosmarinus officinalis and Psidium guajava extract by following the pad-dry-cure method. The presence of phytochemical compounds was ascertained through Thin Layer Chromatography (TLC) and the existence of the functional group in the herbal extract was analyzed by Fourier Transform Infrared Spectroscopy (FTIR). Microcapsules are prepared from the herbal extract using an ionic gelation process and applied to organic cotton fabric. The size of the particle present in the microencapsulated extract was confirmed using Scanning Electron Microscope. The antibacterial activity of the herbal extract and treated cotton fabric was evaluated using the agar well diffusion and parallel streak method. A high zone of inhibition attained against Escherichia coli and Staphylococcus aureus indicates antibacterial potency of the extract. The thickness, stiffness, air permeability, vertical wicking length, and water vapour permeability properties were marginally affected after treatment. The wound healing analysis of the treated fabrics was carried out using an in-vitro wound healing scratch assay.

Polytypism of Cronstedtite From Nagybörzsöny, Hungary

AbstractThe present study provides an example of the accurate identification of polytypes of trioctahedral 1:1 layered silicates from single-crystal X-ray diffraction data collected with the aid of a four-circle diffractometer equipped with an area detector. Single crystals of the mineral cronstedtite from the Nagybörzsöny gold ore deposit, northern Hungary, were studied. The chemical composition of some crystals was determined by electron probe microanalysis (EPMA). The precession-like images of the reciprocal space (RS) sections created by the diffractometer software and presented in the study were used to determine the OD (ordered-disordered) subfamilies (Bailey’s groups A, B, C, D) and particular polytypes. With one exception, all crystals studied belong to subfamily A. The rare polytype 1M, a = 5.51, b = 9.54, c = 7.33 Å, β = 104.5°, space group Cm is relatively abundant in this occurrence. Another polytype 3T, a = 5.51, c = 21.32 Å, space group P31 was also found. Both polytypes occur separately or in mixed, mostly 1M dominant crystals. Some 1M polytype crystals are twinned by order 3 reticular merohedry with a 120° rotation along the chex axis as the twin operation. A rare 1M+3T mixed crystal with 1M part twinned also contains a small amount of subfamily C. A possible presence of the most common 1T polytype of this subfamily cannot be confirmed because of overlap of the characteristic reflections with those of 3T. Several completely disordered crystals produced diffuse streaks instead of discrete characteristic reflections on the RS sections. The EPMA revealed Fe, Si, traces of Mg, Al, S, and Cl. One black crystal originally considered to be cronstedtite was identified as (111) twinned sphalerite. Some crystals of cronstedtite are covered partially by a honey-brown crust or small crystals of siderite.

Nanostructure with diffuse streaks in ScRh3B0.6 compound studied by electron microscopy

We have investigated a characteristic nanostructure with sharp diffuse streaks in a Cu3Au/anti-perovskite-type ScRh3B0.6 compound by electron diffraction, and phase- and Z-contrast high-resolution electron microscopy. The electron diffraction patterns reveal diffuse streaks running along <111>* directions and 121212–type superlattice reflections. The maxima of the streaks can be expressed as a modulation vector q (= α·(af* + bf* + cf*), α = 0.384). The observed HRTEM image taken along the [011] direction with the diffuse streaks indicates a planar domain structure on {111} planes. The superlattice is due to boron/vacancy orderings with planar nanodomains. The diffuse streaks in reciprocal space correspond to well-ordered domains with disturbed periodicity along the <111> directions.

Fluorescent detection of nisin by genetically modified Lactococcus lactis strains in milk and a colonic model: Application of whole-cell nisin biosensors

Detection of bioactive peptides in complex ecosystems like intestinal environment is a difficult task. In this study, we developed two new bioreporters for nisin based on Lactococcus lactis NZ9000 transformed with the vector pNZ:Nis-aFP or pNZ:Nis-mCherry, that encoded for the anaerobic fluorescent protein evoglow-Pp1 (aFP) or the fluorescent protein mCherry, respectively. The biosensors were used to study nisin A production by L.lactis INIA 650 in milk and in a colonic model. The use of L.lactis NZ9000 pNZ:Nis-aFP as a biosensor allowed the detection of nisin produced by L.lactis INIA 650 in milk, but not in the invitro colonic model. In milk, this reporter was induced by direct addition of 10ng/ml nisin while, in the colonic model, nisin concentrations of 50ng/ml were necessary. However, the reporter system based on pNZ:Nis-mCherry showed a higher sensibility, detecting nisin concentrations of 1ng/ml produced by L.lactis INIA 650 in colonic media using agar diffusion or cross streak bioassays.

ω precipitation: Deformation regulator in metastable titanium alloys

The deformation mechanism of a binary metastable titanium alloy Ti–15Mo that had been subjected to various heat treatment regimes was investigated in this work. Microstructures and diffuse streaks were revealed using electron back-scattered diffraction (EBSD) and transmission electron microscopy (TEM). The evolution of the deformation mechanisms were identified as being from primary and secondary {332} twinning → {332} twinning + {112} twinning → {332} twinning + {112} twinning + dislocation slips → dislocation slips with varying initial microstructures. The diffuse streaks corresponding to the soft-phonon shuffling along the {110}<110>β direction were caused by the substitutional Mo atoms and their local strain fields. These nano-sized modulated structures were strongly influenced by phase stability and also proved to serve as a critical factor in deformation mechanisms of this material. Meanwhile, the preferential growth of a nano-sized modulated structure variant took place and was studied to highlight the relationship between loading direction and grain orientation.

Evidence of anatase intergrowths formed during slow cooling of reduced ilmenite

Controlling the parameters during synthetic rutile production is essential to minimize production costs and ensure final product quality. Powder X-ray diffraction (PXRD) is typically used within the industry to guide process control. This work investigated the source of unusual features observed in the PXRD pattern of a slow-cooled reduced ilmenite (RI), which were not observed for a rapid-cooled RI. For the slow-cooled RI, the 002 peak of M3O5 (anosovite) had disappeared and the intensity of the \bar 203, 203, 204 and 402 peaks had decreased significantly compared to the pattern for the rapid-cooled RI. Using transmission electron microscopy, selected area electron diffraction (SAED) and pair distribution function (PDF) analysis, the authors attribute these features to M3O5–anatase intergrowth formation, which causes a loss in long-range order along the M3O5 c axis. Strong diffuse streaking in the SAED patterns was also evident and supported the presence of disordered intergrowths from the oxidation of M3O5. PDF analysis showed a significant improvement in the fit to the data for the slow-cooled RI, primarily in the <17 A region, when anatase was added to the PDF model. The results presented here highlight the importance of the reduction and cooling stages during the formation of these industrially relevant RI minerals, which may be used to direct the production process and final TiO2 product quality.

Evaluation of Antimicrobial Profile of Some Novel 1, 3, 4-Oxadiazole Derivatives Followed by Molecular Docking Against 3G7E Bacterial DNA Gyrase

The main aim and objective of the present research work was the design, synthesis, spectral characterization and evaluation of in vitro antimicrobial profile of some novel oxadiazole derivatives followed by molecular docking studies against bacterial DNA gyrase. The molecular structures of the synthesized compounds were assigned by IR, NMR and Mass spectral analysis. Molecular docking studies were carried out by AUTO DOCK programme. The in vitro antibacterial and antifungal activities were done by paper disk diffusion and agar streak dilution technique. In silico molecular docking studies the binding energy of synthesized compounds (AB1-AB8) were found to be -7.66, -7.67, -7.12, -7.12, -6.59, -6.46, -7.35, -5.09 which indicated that the compound had the high binding affinity towards the bacterial DNA gyrase with PDB id 3G7E and inhibit the function topoisomerase in comparison with standard drug ciprofloxacin (-7.44). The preliminary antimicrobial screening displayed that most of the synthesized compounds were executed moderate to good antimicrobial activity against following bacteria: S. aureus (ATCC 9144), B. subtilis (ATCC 6633), S. epidermidis (ATCC 12228), P. Aeruginosa (ATCC27853), E.coli (ATCC25922), V. cholerrae (ATCC14035) and fungi: A. Niger (ATCC 9029), A.flavus (ATCC204304), C. albicans (ATCC10231) and B. dermatitis (ATCC 26199) etc. All the synthesized compounds exhibited moderate to good antibacterial and antifungal activity with an MIC range of 12-37µg/ml. Among these eight synthesized oxadiazole derivatives, compound AB1; AB2 and AB7 were found to be very good antibacterial as well as antifungal potentiality with an MIC range of 13-12 µg/ml; 7-10 µg/ml and 15-18 µg/ml. Keywords: Molecular docking; NMR; disk diffusion; antibacterial; antifungal and MIC etc.

Cholesterol crystals in pericardial effusion

Atherosclerosis is a disease in which the arterial intima thickens and transforms into a sclerotic plaque, interfering with normal blood flow and potentially leading to stroke or death. It is divided into three stages: the pre-stage, which is characterized by diffuse intimal thickenings (DITs) and fatty streaks, the early atherosclerotic stage, which is characterized by pathological intimal thickening (PIT), and the late stage, which is characterized by fibroatheromas transformed from PIT. Each stage of atherosclerosis is distinguished by distinct morphological changes, biological changes, and the expression of immune markers at various levels. This review summarizes discoveries and achievements in microanatomy, ultrastructure, immunohistochemical staining, and molecular biology in the literature on atherosclerosis. Based on our research, we have emphasized common histological changes and pathological mechanisms of atherosclerosis in this review.

Structural characteristics of m-plane AlN substrates and homoepitaxial films

Homoepitaxial non-polar AlN films were realized on m-plane (101-0)-oriented AlN single crystals by metalorganic chemical vapor deposition (MOCVD). The microstructural properties of m-plane AlN substrates and homoepitaxial films were assessed by means of atomic force microscopy and high resolution x-ray diffraction characterization. Results indicated that both m-plane AlN substrates and films possessed exceptional structural quality, with some anisotropic mosaic distributions due to the quasi-bulk nature of the non-polar single crystals. An increase in the MOCVD growth temperature was noted to minimize the degree of inherited mosaic anisotropy without altering the m-plane AlN film growth rate, indicating that high temperature growth is critical to produce optimal film crystallinity. A dramatic change in the film surface morphology from heavily faceted “slate-like” features to monolayer steps was observed as the growth temperature was increased. The “slate-like” surface morphology produced low intensity cross-streaks in symmetric (101-0) reciprocal space maps, tilted about 18° away from the (101-0) crystal truncation rod. The orientation of these diffuse streaks corresponds to the physical alignment of the slates with respect to the substrate surface normal. X-ray line scans and defect-selective reciprocal space mapping confirmed that these low intensity streaks are solely dependent on this peculiar surface structure produced at low MOCVD growth temperatures and unrelated to basal plane stacking faults or other extended defects. All observations confirm that high quality III-nitride epitaxial structures on m-plane AlN substrates are attainable with controllable MOCVD growth processes, as demanded for future high performing AlN-based non-polar devices.