Surface Scanning Electron Microscopy Research Articles

Fabrication of 100-Oriented (Na0.5K0.5)NbO3–BaZrO3–(Bi0.5Li0.5)TiO3 Films on Si Substrate Using LaNiO3 Layer

0.92(Na0.5K0.5)NbO3–0.06BaZrO3–0.02(Bi0.5Li0.5)TiO3 (NKN–BZ–BLT) thin films were fabricated by pulsed laser deposition (PLD) on a (100)Si substrate on which a 100-oriented LaNiO3 (LNO) bottom layer was fabricated by the chemical solution deposition method. The NKN–BZ–BLT films were characterized by X-ray diffraction (XRD) analysis, θ/2θ scan and ψ–2θ/ω scan, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The properties were compared with those of the NKN–BZ–BLT film deposited on the (111)Pt/Ti/SiO2/(100)Si substrate. We demonstrated that the LNO layer plays an important role in obtaining 100-oriented NKN–BZ–BLT films on the Si substrate. SEM surface and cross-sectional images showed that the NKN–BZ–BLT films fabricated at a substrate temperature of 800 °C had a high density and a relatively smooth surface. From the TEM image, this NKN–BZ–BLT film fabricated at 800 °C was composed of the columnar grains and some vertical-long pores could be observed. The energy dispersive X-ray (EDX) analysis showed that the LNO layer is decomposed to La2NiO4 by its reaction with Nb. The dielectric properties showed that the NKN–BZ–BLT film on the LNO electrode had a small dielectric constant of 82, compared with the NKN–BZ–BLT film (εr = 3127) on the (111)Pt/Ti/SiO2/(100)Si substrate. This difference is due to the polarization direction of the film and the polarization axis of the NKN–BZ–BLT film on the LNO electrode exists in a direction perpendicular to the surface of the substrate. However, the NKN–BZ–BLT film on LNO showed a small Pr value. This is due to the dispersion of Ni from the LNO layer.

Fabrication of 100-Oriented (Na0.5K0.5)NbO3–BaZrO3–(Bi0.5Li0.5)TiO3Films on Si Substrate Using LaNiO3Layer

0.92(Na0.5K0.5)NbO3–0.06BaZrO3–0.02(Bi0.5Li0.5)TiO3 (NKN–BZ–BLT) thin films were fabricated by pulsed laser deposition (PLD) on a (100)Si substrate on which a 100-oriented LaNiO3 (LNO) bottom layer was fabricated by the chemical solution deposition method. The NKN–BZ–BLT films were characterized by X-ray diffraction (XRD) analysis, θ/2θ scan and ψ–2θ/ω scan, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The properties were compared with those of the NKN–BZ–BLT film deposited on the (111)Pt/Ti/SiO2/(100)Si substrate. We demonstrated that the LNO layer plays an important role in obtaining 100-oriented NKN–BZ–BLT films on the Si substrate. SEM surface and cross-sectional images showed that the NKN–BZ–BLT films fabricated at a substrate temperature of 800 °C had a high density and a relatively smooth surface. From the TEM image, this NKN–BZ–BLT film fabricated at 800 °C was composed of the columnar grains and some vertical-long pores could be observed. The energy dispersive X-ray (EDX) analysis showed that the LNO layer is decomposed to La2NiO4 by its reaction with Nb. The dielectric properties showed that the NKN–BZ–BLT film on the LNO electrode had a small dielectric constant of 82, compared with the NKN–BZ–BLT film (er = 3127) on the (111)Pt/Ti/SiO2/(100)Si substrate. This difference is due to the polarization direction of the film and the polarization axis of the NKN–BZ–BLT film on the LNO electrode exists in a direction perpendicular to the surface of the substrate. However, the NKN–BZ–BLT film on LNO showed a small Pr value. This is due to the dispersion of Ni from the LNO layer.

Demonstration of crystal–vapor equilibrium leading to growth blockade of GaN during selective area growth

The synthesis of GaN by selective area growth using Hydride Vapor Phase Epitaxy (SAG-HVPE) is reported for stripes patterned along 〈11¯00〉 and 〈112¯0〉GaN on c-plane sapphire substrates. A systematic control of the GaN morphologies was carried out by both cross-sectional and surface Scanning Electron Microscopy (SEM). A complete HVPE cartography of GaN-SAG revealed domains of zero growth rates at high concentration of hydrogen in the carrier gas. The determination of the mechanisms that govern the growth of GaN morphologies was particularly emphasized. A theoretical model based on thermodynamic and kinetic analyses of the grown (0001) GaN layers was discussed, in combination with experiments on unmasked (0001) GaN and patterned GaN/c-plane sapphire substrates. Long HVPE runs were performed to demonstrate that the prevailing growth mechanism, for high hydrogen concentration in the carrier gas, is a mechanism based on a dechlorination by GaCl2 gas species. This mechanism leads to growth blockade of GaN growth and constitutes a very interesting issue for shaping GaN material as an alternative to top-down micro- and nano-technologies.

Microbiologically influenced corrosion (MIC) in stainless steel heat exchanger

Corrosion attack in the form of corrosion product tubercles was observed in an AISI 304 (EN 1.4301) stainless steel heat exchanger only after 36 months of service. Failure analyses revealed that in one of the attacked areas corrosion had penetrated the entire wall thickness of 6.2mm, but in most of the cases it reached the depth of 2–4mm. In this paper, we report the results from a thorough microstructural characterization of the corroded heat exchanger carried out with optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray diffractometry (XRD).Microstructural studies by OM, SEM and XRD revealed a two-phase structure of austenite and ferrite in the bulk material, as well as the preferential attack of the ferrite phase. SEM surface studies disclosed bacteria in and close to the attacked areas. Cross-sectional SEM examinations showed the distribution and composition of corrosion products within and underneath the tubercles. TEM and XRD studies gave information about the amorphous and/or nanocrystalline nature of some of the formed corrosion products. These results are discussed in this paper and, based on them, the main corrosion mechanism for the observed attack is suggested. Further, explanations for the propagation of corrosion along the ferrite phase are presented.

Quercetin-Phospholipid Complex: An Amorphous Pharmaceutical System in Herbal Drug Delivery

Development of amphiphilic drug-lipid complexes is a potential approach for improving therapeutic efficacy of the drugs by increasing solubility, release profile and oral bioavailability. Quercetin (3, 3', 4', 5, 7-pentahydroxyflavone), a polyphenolic flavonoid, shows several biological effects like anti-inflammatory, anti-cancer, antiproliferative, antimutagenic and apoptosis induction but its use is limited due to its low aqueous solubility. To overcome this limitation, a value added phospholipid complex of quercetin was developed to improve its aqueous solubility for better absorption through the gastrointestinal tract and this might result in improved bioavailability. The quercetin-phospholipid complex thus prepared was evaluated for various physico-chemical parameters like infra red spectroscopy (FT-IR), differential scanning calorimetry (DSC), X-ray powder diffractometry (XRPD), scanning electron microscopy (SEM) and solubility study. The In vitro antioxidant activity was also studied. The phospholipid complex of quercetin was found to be fluffy and porous with rough surface in SEM. FTIR, DSC and XRPD data confirmed the formation of phospholipid complex. The water solubility of quercetin was improved by 12 folds (from 3.44 μg/ ml to 36.81 μg/ ml) in the prepared complex. There was no statistical difference between the quercetin complex and quercetin in the In vitro anti-oxidant activity, indicating that the process of complexation did not adversely affect the bioactivity of the active ingredient.

Surface morphology and composition studies in InGaN/GaN film grown by MOCVD

InGaN films were deposited on (0001) sapphire substrates with GaN buffer layers under different growth temperatures by metalorganic chemical vapor deposition. The In-composition of InGaN film was approximately controlled by changing the growth temperature. The connection between the growth temperature, In content, surface morphology and defect formation was obtained by X-ray diffraction, scanning electron microscopy (SEM) and atomic force microscopy (AFM). Meanwhile, by comparing the SEM and AFM surface morphology images, we proposed several models of three different defects and discussed the mechanism of formation. The prominent effect of higher growth temperature on the quality of the InGaN films and defect control were found by studying InGaN films at various growth temperatures.

Improvement of the Oxidation and Wear Resistance of Pure Ti by Laser-Cladding Ti3Al Coating at Elevated Temperature

Ti3Al coating was in situ synthesized successfully on pure Ti substrate by laser-cladding technology using aluminum powder as the precursor. The composition and microstructure of the prepared coating were analyzed by transmission electron microscopy, scanning electron microscopy (SEM), and X-ray diffraction technique. Thermal gravimetric analysis was used to evaluate the high-temperature oxidation resistance of the Ti3Al coating. The friction and wear behavior was tested through sliding against Si3N4 ball at elevated temperature of 20, 100, 300, and 500°C. The morphologies of the worn surfaces and wear debris were also analyzed by SEM and three-dimensional non-contact surface mapping. The results show that the Ti3Al coating with high microhardness, high-temperature oxidation resistance, and high temperature wear resistance. The pure Ti substrate is dominated by severe adhesion wear, abrasive wear, fracture, and severe plastic deformation at lower temperature, and severe adhesion wear, abrasive wear, plastic deformation, oxidation, and nitriding wear at higher temperature, whereas the Ti3Al coating experiences only moderate abrasive and adhesive wear when sliding against the Si3N4 ceramic ball counterpart. In addition, the wear debris of the laser-cladding Ti3Al coating sliding and Si3N4 friction pairs are much smaller than that of pure Ti substrate and Si3N4 friction pairs at elevated temperature.

Enhancement of the photocatalytic activity of TiO 2 by doping it with calcium ions

Titanium dioxide (TiO 2) with an enhanced photocatalytic activity was developed by doping it with calcium ions through a sol–gel method. The developed photocatalysts were characterized by Fourier transform infrared (FTIR) spectroscopy, N 2 physisorption, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction. Their surface morphologies were studied using surface scanning electron microscopy (SEM). The XPS analyses confirmed the presence of Ti, O, Ca, and C in the Ca-doped TiO 2 sample. The activities of the catalysts were evaluated by photocatalytic degradation of an azo dye, acid red 1 (AR1), using UV light irradiation. The results of the investigations revealed that the samples calcined at 300 °C for 3.6 h in a cyclic (2 cycles) mode had the best performance. Lower percentage dopant, 0.3–1.0 wt.%, enhanced the photocatalytic activity of TiO 2, with the best at 0.5 wt.% Ca–TiO 2. The performance of 0.5 wt.% Ca–TiO 2 in the degradation of AR1 was far superior to that of a commercial anatase TiO 2 Sigma product CAS No. 1317-70-0. The effect of pH on the degradation of AR1 was studied, and the pH of the dye solution exerted a great influence on the degradation of the dye.

Nuclear characterization and investigation of radioactive bioglass seed surfaces for brachytherapy via scanning electron microscopy

This paper aims to analyze images created through scanning electron microscopy (SEM) of the surfaces of radioactive bioglass seeds for brachytherapy implants. The SEM surface images were taken of bioglass seeds made of [Si:Ca:Ho] with Zr and Ba contrast agents and of seeds made of [Si:Ca:Sm] with Ba contrast agent. The following groups were considered: bioglass seeds after synthesis, seeds after irradiation and surface-induced fractures. The SEM image pre-processing required an appropriate mounting support following metallization with gold to fix the bioglass seeds made of inorganic elements. The microscope images were analyzed and showed surface changes among the seed groups. Nuclear characterization of the radioactive bioglass seeds by gamma spectrometry provided the gamma signatures of Sm-153 and Ho-166 followed by the contrast agents. The particle ranges on ceramic; water and tissue were also analyzed using gamma and beta particle evaluations. The results complement the study of the characterization and biodegradability of radioactive bioglass seeds for brachytherapy implants.

Cryogenic EBSD on ice: preserving a stable surface in a low pressure SEM

Naturally deformed ice contains subgrains with characteristic geometries that have recently been identified in etched surfaces using high-resolution light microscopy (LM). The probable slip systems responsible for these subgrain boundary types can be determined using electron backscattered diffraction (EBSD), providing the etch features imaged with reflected LM can be retained during EBSD data acquisition in a scanning electron microscope (SEM). Retention of the etch features requires that the ice surface is stable. Depending on the pressure and temperature, sublimation of ice can occur. The equilibrium temperature for a low pressure SEM operating at 1 × 10(-6) hPa is about -112°C and operating at higher temperatures causes sublimation. Although charging of uncoated ice samples is reduced by sublimation, important information contained in the etch features are removed as the surface sublimes. We developed a method for collecting EBSD data on stable ice surfaces in a low pressure SEM. We found that operating at temperatures of <-112°C reduced sublimation so that the original etch surface features were retained. Charging, which occurred at low pressures (<1.5 × 10(-6) to 2.8 × 10(-5) hPa) was reduced by defocusing the beam. At very low pressures (<1.5 × 10(-6) hPa) the spatial resolution with a defocused beam at 10 kV was about 3 μm in the x-direction at -150°C and 0.5 μm at -120°C, because at higher temperature charging was less and only a small defocus was needed to compensate it. Angular resolution was better than 0.7° after orientation averaging. Excellent agreement was obtained between LM etch features and EBSD mapped microstructures. First results are shown, which indicate subgrain boundary types comprised of basal (tilt and twist) and nonbasal dislocations (tilt boundaries).

Development and Characterization of Aspirin-Phospholipid Complex for Improved Drug Delivery

Aspirin (acetylsalicylic acid) is one of the most widely used analgesic. Aspirin is poorly soluble in water and causes gastrointestinal (GI) irritation. To improve the solubility (and hence the bioavailability) and minimize the GI irritation, its complexes with soya-phospholipid-80 % (in 1: 1 molar ratio) were prepared in an organic solvent and evaluated for solubility, drug content, scanning electron microscopy (SEM), FT-IR spectra, X ray diffraction, differential scanning calorimetry (DSC) and in vitro dissolution study. Aspirin-phospholipid complex were found to be disc shaped with rough surface in SEM. Drug content in the complex was found to be 95.6 %. DSC thermograms, XRD and FTIR confirmed the formation of phospholipid complex. Solubility of the prepared complex was found to be improved. Aspirin complex and aspirin showed 90.93 % and 69.42 % of drug release at the end of 10 h in dissolution study in pH 1.2 acid buffer. It was concluded that the phospholipid complex of aspirin may be of potential use for improving the solubility of aspirin and hence its bioavailability. The complexes may also reduce GI toxicity of the drug.

A NEW METHOD FOR MACHINING OF ELECTRICALLY NONCONDUCTIVE WORKPIECES USING ELECTRIC DISCHARGE MACHINING TECHNIQUE

In this study, a new method for machining of nonconductive ceramic workpieces in electric discharge machining (EDM) was developed. Machining surfaces of nonconductive workpieces were coated with a conductive layer (CL) and graphite powder was added to dielectric fluid for machining. Al2O3, ZrO2, SiC, B4C and glass workpiece samples were machined by using the method. Different machining conditions were tested for each sample and optimum machining parameters were determined. Effect of electrical conductivity, thermal conductivity and melting point of workpieces on material removal rate (MRR) was investigated. Optical microscope and SEM (Scanning Electron Microscope) surface photographs of workpieces taken after machining are presented and discussed.

Preparation and characterization of phospholipid complexes of naringenin for effective drug delivery

Naringenin is a flavonoid specific to citrus fruits and possesses anti-inflammatory, anticarcinogenic, and antitumour effects. But due to a lower half-life and rapid clearance from the body, frequent administration of the molecule is required. To improve the bioavailability and prolong its duration in body system, its phospholipid complexes were prepared by a simple and reproducible method. Naringenin was complexed with phosphatidylcholine in equimolar ratio, in presence of dichloromethane. The prepared Phytosomes (naringenin–phospholipid complex) were evaluated for various physical parameters like FT-IR spectroscopy, Differential Scanning Calorimetry (DSC), X-ray powder diffractometry (XRPD), Solubility, Scanning Electron Microscopy (SEM) and the in vitro drug release study. These phospholipid complexes of naringenin were found to be irregular and disc shaped with rough surface in SEM. Drug content was found to be 91.7% (w/w). FTIR, 1H NMR, DSC and XRPD data confirmed the formation of phospholipid complex. Water solubility of naringenin improved from 43.83 to 79.31 μg/mL in the prepared complex. Unlike the free naringenin (which showed a total of only 27% drug release at the end of 10 h), naringenin complex showed 99.80% release at the end of 10 h of dissolution study. Thus it can be concluded that the phospholipid complex of naringenin may be of potential use for improving bioavailability.

Study on tribological behavior and cutting performance of CVD diamond and DLC films on Co-cemented tungsten carbide substrates

The tribological behaviors of diamond and diamond-like carbon (DLC) films play a major role on their machining and mechanical applications. In this study, diamond and diamond-like carbon (DLC) films are deposited on the cobalt cemented tungsten carbide (WC–Co) substrate respectively adopting the hot filament chemical vapor deposition (HFCVD) technique and the vacuum arc discharge with a graphite cathode, and their friction properties are evaluated on a reciprocating ball-on-plate tribometer with counterfaces of silicon nitride (Si 3N 4) ceramic, cemented tungsten carbide (WC) and ball-bearing steel materials, under the ambient air without lubricating condition. Moreover, to evaluate their cutting performance, comparative turning tests are conducted using the uncoated WC–Co and as-fabricated CVD diamond and DLC coated inserts, with glass fiber reinforced plastics (GFRP) composite materials as the workpiece. The as-deposited HFCVD diamond and DLC films are characterized with energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), Raman spectroscopy and 3D surface topography based on white-light interferometry. Furthermore, Rocwell C indentation tests are conducted to evaluate the adhesion of HFCVD diamond and DLC films grown onto WC–Co substrates. SEM and 3D surface topography based on white-light interferometry are also used to investigate the worn region on the surfaces of diamond and DLC films. The friction tests suggest that the obtained friction coefficient curves that of various contacts exhibit similar evolution tendency. For a given counterface, DLC films present lower stable friction coefficients than HFCVD diamond films under the same sliding conditions. The cutting tests results indicate that flank wear of the HFCVD diamond coated insert is lower than that of DLC coated insert before diamond films peeling off.

Microstructural and electrical properties of CaTiO3–CaCu3Ti4O12 ceramics

Abstract This study investigates the microstructure and dielectric properties of (CTO)1−x–(CCTO)x ceramics. X-ray diffraction (XRD) patterns show that the crystal phases of polycrystalline CCTO exhibit a (2 2 0) preferential orientation at the molar fraction x = 1. For (CTO)2/3–(CCTO)1/3 or (CTO)1/3–(CCTO)2/3 ceramics, the crystalline structures of CTO and CCTO coexist at x = 1/3 and 2/3, respectively. Surface scanning electron microscope (SEM) morphologies show that the CCTO with x = 1 sintered above 1010 °C exhibits liquid-phase secondary recrystallization (LPSR) regions, and these regions expand as the sintering temperature increases. Therefore, the grain size and ceramics density depends on the sintering temperature and composition. This suggests that CCTO prepared at x = 1 can be a good candidate for capacitor applications because of its high ɛ value. The dielectric properties of CCTO sintered at 1100 °C include a dielectric constant (ɛ) of 23,600, dielectric loss (tan δ) of 0.406 at 10 kHz, leakage current density (J) of 6.11 × 10−6 A/cm2 and conductivity (σ) of 6.11 × 10−9 Ω cm−1 at 1 kV/cm.

Fixation and Drying Protocols for the Preparation of Cell Samples for Time-of-Flight Secondary Ion Mass Spectrometry Analysis

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is a promising tool for subcellular chemical analysis of biological cells. However, to obtain relevant information, the method used for sample preparation is critical. In this work, we have used TOF-SIMS, scanning electron microscopy (SEM), and interference reflection microscopy (IRM) to study the effects of different fixation and drying methods on the morphology and chemical structure of human fibroblast cells (hTERT) adhered to a silicon surface. Specifically, two fixation techniques (chemical fixation with glutaraldehyde and cryofixation by plunge freezing) and two drying techniques (freeze drying and alcohol substitution drying) were investigated. Cryofixation followed by freeze drying was determined to produce dried cells with preserved cell morphology, intact cell membranes, and retained sodium/potassium ion concentration gradients across the plasma membrane. By washing samples in an aqueous solution of ammonium formate (AF) before cryofixation, the accumulation of salts on the sample surface during drying could be suppressed. IRM measurements showed that the cell morphology was preserved during washing with ammonium formate, although some swelling occurred. Compared with cryofixation, cells fixed with glutaraldehyde showed finer structures on the cell surface in SEM and similar lipid distributions in TOF-SIMS, but the sodium/potassium ion gradients were not retained. Alcohol drying was determined to remove cell membrane phospholipids significantly, although the use of osmium tetroxide as a post-fixative was shown to decrease this effect.

Effect of processing on the crystalline orientation, morphology, and mechanical properties of polypropylene cast films and microporous membrane formation

Cast films of a high molecular weight linear polypropylene (L-PP) were prepared by extrusion followed by stretching using a chill roll. An air knife was employed to supply air to the film surface right at the exit of the die. The effects of air cooling conditions, chill roll temperature, and draw ratio on the crystalline orientation, morphology, mechanical and tear properties of the PP cast films were investigated. The crystallinity and crystal size distribution of the films were studied using differential scanning calorimetry (DSC). It was found that air blowing on the films contributed significantly to the uniformity of the lamellar structure. The orientation of crystalline and amorphous phases was measured using wide angle X-ray diffraction (WAXD) and Fourier transform infrared (FTIR). The amount of lamellae formation and long period spacing were obtained via small angle X-ray scattering (SAXS). The results showed that air cooling and the cast roll temperature have a crucial role on the orientation and amount of lamellae formation of the cast films, which was also confirmed from scanning electron microscopy (SEM) images of the films. Tensile properties and tear resistance of the cast films in machine and transverse directions (MD and TD, respectively) were evaluated. Significant increases of the Young modulus, yield stress, tensile strength, and tensile toughness along MD and drastic decreases of elongation at break along TD were observed for films subjected to air blowing. Morphological pictograms are proposed to represent the molecular structure of the films obtained without and upon applying air cooling for different chill roll temperatures. Finally, microporous membranes were prepared from annealed and stretched films to illustrate the effect of the PP cast film microstructure on the morphology and permeability of membranes. The observations of SEM surface images and water vapor transmission rate of the membranes showed higher pore density, uniform pore size, and superior permeability for the ones obtained from the precursor films prepared under controlled air cooling.

Surface chemical states of barium zirconate titanate thin films prepared by chemical solution deposition

Ba(Zr 0.05Ti 0.95)O 3 (BZT) thin films grown on Pt/Ti/SiO 2/Si(1 0 0) substrates were prepared by chemical solution deposition. The structural and surface morphology of BZT thin films has been studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results showed that the random oriented BZT thin film grown on Pt/Ti/SiO 2/Si(1 0 0) substrate with a perovskite phase. The SEM surface image showed that the BZT thin film was crack-free. And the average grain size and thickness of the BZT film are 35 and 400 nm, respectively. Furthermore, the chemical states and chemical composition of the films were determined by X-ray photoelectron spectroscopy (XPS) near the surface. The XPS results show that Ba, Ti, and Zr exist mainly in the forms of BZT perovskite structure.

Behavior of tungsten with exposure to deuterium plasmas

Four kinds of tungsten (W) materials, i.e. (1) foil of 50μm thick (f-W), (2) polycrystalline (Pc-W) with grain size of ∼3μm, (3) recrystallized (Re-W) with grain size of ∼50μm and (4) vacuum plasma spraying (VPS-W) coatings, were irradiated employing linear plasma generators, with fluxes ⩾1×1022D/m2/s and energies ⩽100eV/D. Scanning electron microscopy (SEM) was used to observe blister formation at the surfaces. The SEM surface morphology and cross section observation indicates that blister formation is related to the microstructure and surface state of different material grades. Results of trapping and deuterium retention measured by thermal desorption spectroscopy (TDS) and nuclear reaction analysis (NRA) show also a close correlation between the retention and the microstructure and surface state.

Detection of interproximal demineralized lesions on human teeth in vitro using frequency-domain infrared photothermal radiometry and modulated luminescence

Frequency-domain photothermal radiometry (FD-PTR or PTR) is used to detect mechanical holes and demineralized enamel in the interproximal contact area of extracted human teeth. Thirty-four teeth are used in a series of experiments. Preliminary tests to detect mechanical holes created by dental burs and 37% phosphoric acid etching for 20 s on the interproximal contact points show distinct differences in the signal. Interproximal contact areas are demineralized by using a partially saturated acidic buffer system. Each sample pair is examined with PTR before and after micromachining or treating at sequential treatment periods spanning 6 h to 30 days. Dental bitewing radiographs showed no sign of demineralized lesion even for samples treated for 30 days. Microcomputer tomography (micro-CT), transverse microradiography (TMR), and scanning electron microscopy (SEM) analyses are performed. Although micro-CT and TMR measured mineral losses and lesion depths, only SEM surface images showed visible signs of treatment because of the minimal extent of the demineralization. However, the PTR amplitude increased by more than 300% after 80 h of treatment. Therefore, PTR is shown to have sufficient contrast for the detection of very early interproximal demineralized lesions. The technique further exhibits excellent signal reproducibility and consistent signal changes in the presence of interproximal demineralized lesions, attributes that could lead to PTR as a reliable probe to detect early interproximal demineralization lesions. Modulated luminescence is also measured simultaneously, but it shows a lower ability than PTR to detect these interproximal demineralized lesions.