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High-temperature mechanical properties of medium-entropy carbide ceramics have attracted significant attention. Tailoring the microstructure is an effective way to improve these high-temperature mechanical properties, which can be affected by the evolution of the enthalpy and entropy, as well as by lattice distortion and sluggish diffusion. In this study, the effects of equiatomic Zr/(Ti,Nb) substitution (Zr content of 10–40 at%) on the microstructure and high-temperature strength of (Ti,Zr,Nb)C medium-entropy ceramics were investigated. The grain size of the (Ti,Zr,Nb)C medium-entropy ceramics was refined from 9.4±3.7 to 1.1±0.4 μm with an increase in the Zr content from 10.0 to 33.3 at%. A further increase in the Zr content to 40 at% resulted in a slight increase in the grain size. At 1900 °C, the (Ti,Zr,Nb)C medium-entropy ceramics with the Zr contents of 33.3 and 40 at% exhibited ultra-high flexural strengths of 875±43 and 843±71 MPa, respectively, which were higher than those of the transition metal carbides previously reported under similar conditions. Furthermore, relatively smooth grain boundaries, which were detected at a test temperature of 1000 °C, transformed into curved and serrated boundaries as the temperature increased to 1900 °C, which may be considered the primary reason for the improved high-temperature flexural strength. The associated mechanism was analyzed and discussed in detail.

Sensitive and rapid detection of nitrobenzene in aqueous media using a fluorescent Eu@Zr-MOF.

Using powders treated by sand milling as starting materials, high densified lithium lanthanum titanium oxide (LLTO) ceramics with high conductivity were prepared. A novel all-solid-state reference electrode was fabricated using the as-prepared LLTO ceramics for electrochemical measurements in marine environments that require robustness, no clogging, and resistance to high salinity and high temperatures and pressures. This reference electrode functioned without any filling solution and any porous junction between it and the analyte. The characteristics, stability, and impedance of the all-solid-state reference electrode were examined in different pH buffer aqueous solutions; its I–V curves were recorded during cyclic voltammetric experiments, which were then compared with those obtained for a classic Ag/AgCl reference electrode. The fabricated reference electrode was connected to an Ir/IrO2 working electrode to prepare an all-solid-state pH sensor for measuring the pH of simulated seawater and for capturing variations in the behavior of the reference electrode on addition of acidic or alkaline solutions. This all-solid-state potentiometric sensor can be used in association with other sensing electrodes and in harsh environments, such as at great ocean depths and in high temperature and pressure environments.

It has been assumed that the measured strength of ceramics follows a Weibull distribution. However, there is still no sound evidence to confirm this assumption. On the contrary, some studies have shown that other distributions such as normal distribution may describe more appropriately the measured strength data than Weibull distribution. In this paper, an extensive comparison between the efficiencies of normal and Weibull distributions in describing the strength variations was performed based on the analyses of 27 strength datasets, each containing 30 data measured on different ceramics. It was shown based on Anderson–Darling (A–D) test that, in most cases, normal distribution may give a satisfactory description for the data. The analysis results reveal that, at least for the small datasets generally used in laboratory evaluation, it seems to be unnecessary to perform a Weibull analysis because a simple normal distribution analysis is accurate enough for the statistical characterization of strength for the examined materials.

The excellent high temperature phase stability enables the perovskite BaZrO3 to be a promising candidate for thermal barrier coatings (TBCs). Further improvement of its thermo-physical properties is necessary to fulfill the increasing requirements for TBCs. In this work, CaxBa1-xZrO3 (x = 0.05, 0.10, 0.15, 0.20, 0.25) solid solutions are fabricated and the influence of the Ca2+ content on their mechanical/thermal properties is studied. They have moderate mechanical properties and their residual Young's moduli at 1473 K are around 80% of the values at room temperature. Compared with BaZrO3, CaxBa1-xZrO3 solid solutions have decreased thermal conductivities which are comparable to those of YSZ and other potential TBCs materials. Among these solid solutions, Ca0.25Ba0.75ZrO3 exhibits the lowest thermal conductivity that is in the range from 2.06 W ⋅ m - 1 ⋅ K - 1 to 2.52 W ⋅ m - 1 ⋅ K - 1 . Meanwhile, CaxBa1-xZrO3 solid solutions have higher thermal expansion coefficients than that of BaZrO3. These good high temperature mechanical and thermal properties reveal their promising applications as high temperature structural ceramics including TBCs.

It is generally assumed that the measured strength of brittle ceramics follows a Weibull distribution. However, there seems to be few sound and direct evidences to support this assumption. Several previous studies have shown that other distributions, such as normal distribution and log-normal distribution may describe more appropriately the strength data than Weibull distribution. In this paper, the efficiency of using a normal distribution to describe the strength which follows a Weibull distribution is examined based on Monte-Carlo simulations. It was shown that there exist strong correlations between the parameters of normal distribution and those of Weibull distribution. For the designed fracture probability not lower than 0.01, analyses based on both normal distribution and Weibull distribution may give nearly identical predictions for the applicable stress levels. For lower fracture probabilities, the differences between the predictions of both distributions are not significant. It was suggested that, if there is no evidence to confirm that the measured strength follows a certain distribution, normal distribution and Weibull distribution seem to have the same efficiency in analysing the statistical variations in the measured strength of ceramics.

Mesoporous WO3 with diameter of 7 nm and specific surface area of 209 m2/g was prepared by using SBA-15 as the hard template. Designed for ppb-level NO2 detection in air, the as-obtained mesoporous WO3 was employed as the sensing electrode to improve the sensitivity of a mixed-potential-type sensor based on yttria-stabilized zirconia electrolyte. This device showed high sensitivity to NO2 over the concentration range of 0.06–10 ppm at 500 ℃, and the electric potential difference (ΔV) showed good linear correlation with the logarithm of the NO2 concentration. The sensor exhibited high NO2 selectivity, along with excellent repeatability and stability as well. The mixed-potential sensing mechanism was also discussed based on the polarization curves and electrochemical impedances.

The yellow-emitting carbon dots (CDs) were successfully synthesized by a simple one-step hydrothermal route using o-phenylenediamine (o-PD) as the starting material. The emssion peak of CDs shifted from 535 to 563 nm and the corresponding photoluminescence quantum yield (PLQY) enhanced from 10.4% to 23.1% when the reaction solvent of ethanol was replaced by deionized water and reaction temperature was increased by 20 °C. After CDs were effectively and uniformly attached to starch particles by hydrogen bonding and physical adsorption, a new type of environmentally friendly and yellow CDs-based phosphors has been developed. Effective dispersion of small CDs on the surface of large starch particles can lengthen the distance among CDs, as a result, the non-radiative decay process and photoluminescence quenching were steadily hindered. Highly efficient solid-state CDs phosphors with a PLQY of 66.9% were acquired. Combing with the excellent thermal stability and photostability, a daylight white LED based on a single color converter of yellow CDs phosphors was fabricated with a CRI of 83, luminous efficiency of 30.54 lm/W, and CIE coordinates of (0.3429, 0.2817). Suggesting that as-prepared CDs-based phosphors have a great potential in phosphor-based light-emitting devices.

To develop highly efficient T1/T2 magnetic resonance imaging (MRI) contrast agents (CAs), Gd/Y hydroxide nanosheets were synthesized by a simple exfoliation method from layer compounds using sodium polyacrylate (PAA) as a dispersant and stabilizer. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) results revealed the excellent performance of monolayer nanosheets with thicknesses of up to 1.5 nm. The MRI results of the T1 and T2 relaxation times showed that all of the Gd/Y hydroxide nanosheets have high longitudinal and transverse relaxivities (r1 and r2). In particular, the 10% Gd-LRH nanosheets exhibited excellent MRI performance (r1 = 103 mM&minus, 1 s&minus, 1, r2 = 372 mM&minus, 1), which is rarely reported. Based on the relationship between the structure of 10% Gd-LRH nanosheets and their MRI performances, and the highly efficient MRI of spaced Gd atoms in the nanosheets, a special model to explain the outstanding MRI performance of the 10% Gd-LRH nanosheets is suggested. The cytotoxicity assessment of the 10% Gd-LRH nanosheets, evaluated by CCK-8 assays on HeLa cells, indicated no significant cytotoxicity. This study presents a significant advancement in 2D nanomaterial MRI CA research, with Gd-doped nanosheets positioned as highly efficient T1/T2 MRI CA candidates.

Carbon dots (CDs), as a new kind of fluorescent pH nanoprobe, have attracted significant attention due to their favorable optical properties and excellent environmental friendliness. However, a real ratiometric and self-calibrating fluorescent pH nanoprobe based on intrinsic dual-emission CDs (DECDs) still remains scarce. In this study, we reported a kind of intrinsic DECDs for ratiometric fluorescence pH sensing. Interestingly, the two emission bands at 393 and 580 nm from the DECDs simultaneously display strong pH-dependence but with an adverse variation trend. The ratio of the intensity of 393 and 580 nm matches well with an empirical function against pH in the range from 2.2 to 8.0, and further, an excellent linear relationship is presented in an acidic environment with a responsive pH range of 2.2–4.0. Moreover, the rapid response time (

In this study, amperometric NO2 sensors based on Na+ superionic conductor electrolyte and sensing electrodes with different WO3 nanostructures (WO3 nanoparticles, WO3 nanosheets, and mesoporous WO3) have been fabricated and compared. Sensing properties, such as optimum test temperature, sensitivity, repeatability, and selectivity have been determined and compared. Compared with the literatures, the sensors, prepared using three different WO3 nanostructures, all showed improved sensing properties to 100–1000 ppb NO2 at low work temperatures of 100–150 °C. Among above sensors, the sensor equipped with mesoporous WO3 sensing electrode exhibited the best amperometric sensitivity characteristics and the minimum test temperature. The relationship between the sensing properties and the mesoporous structure has also been discussed. What’s more, the sensor can test ppb-level NO2 in low temperature, which makes it possible to monitor low concentrations of NO2 in the air.

In this work, a new Eu and Tb co-doped luminescent compound based on MOF-5, [Zn4O(BDC)3], (named as compound 1) was successfully synthesized. The structure and morphology characterizations demonstrate that the initial framework of MOF-5 is retained well after co-doping Eu and Tb. The systematic investigations of photoluminescence behaviors reveal that the heat-treated compound 1 (called as compound 1a) can be utilized as a multi-channel readout luminescent thermometer in emission intensity ratio, decay time ratio, and luminescence color. It simultaneously exhibits the excellent repetitiveness and reversibility under high temperature region from 303 to 473 K. The relative sensitivity of 1.8%/K at 473 K is much higher than the best one of 1.19%/K previously reported for the mixed-lanthanide MOF Tb0.8Eu0.2BPDA. Until now, such a ratiometric luminescent thermometer with a high sensitivity at the temperature as high as 473 K has been rarely explored.

Systematic Monte Carlo simulations were performed in the present study to examine the effectiveness of two-parameter Weibull function in the characterization of the strength variation and fracture reliability of a material whose strength follows a three-parameter Weibull distribution. It was shown that two-parameter Weibull function is sufficiently suitable for the description of the statistical variation of the conventionally adopted small strength sample, regardless of whether the strength follows a two-parameter or a three-parameter Weibull distribution. Furthermore, for a material whose strength follows a three-parameter Weibull distribution, accurate determinations of the fracture stress corresponding to a given fracture probability may be obtained based on two-parameter Weibull analysis. Therefore, it is concluded that three-parameter Weibull function is not necessary for the analysis of the statistical variation of the fracture strength of brittle ceramics.

1 A luminescent film comprising Eu (Ш)-doped yttrium oxide nanosheets was fabricated by electrophoretic deposition, modified by 2-thenoyltrifluoroacetonate, and coated with polystyrene to obtain a novel oxygen sensor capable of detecting both dissolved (DO) and gaseous (GO) oxygen based on luminescence intensity quenching. Based on the results of luminscence lifetime, the mechanism of molecular oxygen–induced luminescence quenching was discussed in detail. The above film exhibited high sensitivity and a well-linear response, with its high photostability making it a promising material for DO and GO sensing.

In this article, we successfully extracted HA/β-TCP biphasic calcium phosphate from the marine fish bones (Hairtails) by various temperature calcinations. By characterizing, we confirmed that β-TCP was obtained from the calcined products of Hairtails, and the relative content of β-TCP in fish bones calcined at 900 °C significantly increased. In addition, the mechanism of changing the composition ratio of BCP by heating was also discussed. Hairtails as a raw material was used to prepare biphasic calcium phosphate ceramics can be well applied to clinical medicine.

Free bilirubin, when present in excess in the human body, can cause a multitude of diseases and disorders and even be fatal; hence, detecting it is of paramount importance. Herein, we report a luminescence quenching-based non-enzymatic method for the convenient, reliable, and rapid detection of free bilirubin in blood serum samples using sensing films (nanosheets/PS, nanosheets-tta/PS, and nanosheets-dbt/PS) as luminescent sensors. The luminescence intensity of the sensing films is linearly related to the free bilirubin concentration. Nanosheets-tta/PS demonstrated excellent sensing properties for the sensitive and reliable detection of free bilirubin in the range of 0.0-60.0 μM with a correlation coefficient of 0.9915, as compared to nanosheets/PS or nanosheets-dbt/PS. The limit of detection for the determination of free bilirubin was 41 nM. This method can be used to design a sensor-based test spot as a medical detection device for the visual detection of free bilirubin.

A novel green/red dual-emission carbon dots-based phosphor (named as GRCDs phosphor) was successfully prepared by introducing calcium hydroxide [Ca(OH)2] as matrix material mixed with green-emitting carbon dots (CDs) for the first time. The addition of Ca(OH)2 not only prevents fluorescent self-quenching caused by polymerization of CDs in the solid state but also promotes the red emission of CDs due to abundant functional groups on the surface. Furthermore, the detailed characterizations of the structure and optical properties show that the hydroxyl groups play a crucial role for the red emission of GRCDs phosphor. As-prepared GRCDs phosphor possesses outstanding thermal stability as well as excellent water stability. This finding provides a new way for the development of CDs-based phosphors.

To quantify the oxygen content in molten salts, we examined the performance of an yttria-stabilized zirconia solid electrolyte oxygen sensor with a Bi/Bi2O3 reference electrode, focusing on its output accuracy. When the above sensor was tested in a flow of gas with known oxygen partial pressure, $$p_{O_2}$$ , a linear relationship between $$lgp_{O_2}$$ and the electromotive force (EMF) was observed, and the correlation slope exhibited a positive deviation from Nernstian behavior. EMF measurements performed in molten NaCl–KCl indicated that the oxygen content of this salt mixture increased with increasing oxygen partial pressure in the covering gas, in agreement with Henry’s law. Moreover, the EMF exhibited a linear decrease with increasing melt temperature of molten NaCl–KCl, in agreement with the theoretical model. Finally, a relationship between the structure of molten NaCl–KCl and its oxygen diffusion behavior was established. As a result, the developed sensor was demonstrated to be well suited for determining the oxygen content of molten salts.

The aim of this research is to observe the physicochemical characterization and evaluate the biocompatibility of the HA/β-TCP biphasic calcium phosphate ceramics (BCP) produced from fish bones. In addition, the mechanism of the formation of BCP after calcination of fish bones was discussed. Three kinds of fish bones (Salmo salar, Anoplopoma fimbria and Sardine) were prepared and calcined for one hour at different temperatures ranging from 600 °C to 1100 °C in a muffle furnace. The calcined bones were analyzed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (GTA), inductively coupled plasma optical atom emissions spectroscopy (ICP-OES), X-ray fluorescence (XRF) and scanning electron microscopy (SEM). The in vitro cytotoxicity assessment was used to evaluate the biocompatibility of the biphasic ceramics. BCP materials were produced from all kinds of fish bones by calcination above 700 °C, the carbonated hydroxyapatite and multiple trace element were also found in the calcined bones. With the increase of temperature, the ratio of HA/β-TCP varied and the major organic components were progressively removed. The carbonated hydroxyapatite disappeared when temperature rises above 900 °C. Rising temperature also caused crystal growth that eventually gave rise to the increase of the BCP grain size and influenced the mesoporous structure. The BCP materials were confirmed to have no obvious cytotoxicity to mesenchymal stem cells (MSC) in the in vitro cytotoxicity assessment. Calcium-deficient hydroxyapatite(CDHA) may make up the major inorganic constituent of fish bones that could decompose to HA and β-TCP when calcined above 700 °C. 800–900 °C is considered to be the optimal temperature to fabricate BCP materials which contain more β-TCP, carbonated hydroxyapatite and retain distinct mesoporous structure while has good biocompatibility. With the unique composition and structure, these three kinds of fish-bone-derived BCP materials can be further applied to fabricate bioceramic scaffolds for biomedical applications.

Gadolinia-doped ceria (GDC) prepared by the oxalate coprecipitation method was used as an oxygen-ion conducting solid electrolyte for a mixed-potential ammonia gas sensor with a WO 3 -sensitive electrode. The sensing performance of this sensor was compared with a sensor based on yttria-stabilized zirconia (YSZ) electrolyte. The influence of different oxygen-ion electrolytes on the performance of the gas sensor was evaluated. The test results show that the sensor device is much more sensitive (140.44 mV/decade) than the YSZ-based sensor device. Furthermore, the also shows good repeatability and stability. The electrochemical impedance measurements indicate that the GDC-based sensor’s high performance may benefit from the high conductivity of GDC.

Several Ir/IrO2 pH electrodes were prepared by a cyclic thermal oxidation process via dip-coating in a concentrated solution of NaOH. A hydrothermal hydration treatment at 220 °C for 24 h was used to address the problematic potential drift that is common in Ir/IrO2 pH electrodes. The electrodes that were treated by the hydrothermal method exhibited good stability and high sensitivity compared to those that were hydrated at room temperature. The reasons for this improvement were investigated by Raman spectroscopy, X-ray photoelectron spectroscopy, and field emission scanning electron microscopy. The results suggested that the hydrothermally treated electrode had a more orderly crystal arrangement and a higher content of OH− groups, which drove improvements in the performance of electrode by modification of the Ir/IrO2 structure. The relationship between the electrode structure and performance was investigated and discussed in detail herein.

We report a new family of lanthanide-based inorganic-organic hybrid frameworks Y1.9Eu0.1(OH)(5)[C6H5COO] center dot 2H(2)O synthesized by homogeneous precipitation. The crystal structure obtained from powder X-ray diffraction data revealed that this material comprises two-dimensional cationic lanthanide hydroxide {[Ln(2)(OH)(5)(H2O)](+)}(infinity) layers, which are cross-linked by benzoate ligands into a three-dimensional pillared framework. The single layered nanosheets were obtained in n-butanol after the supersonic treatment. The morphologies of the nanosheets were a hexagonal structure about 800 nm in size as determined by transmission electron microscopy, and the thickness of the nanosheets was about 1.8 nm measured by atomic force microscopy. The fluorescence intensity of the D-5(0)-F-7(2) transition increased nearly 3.8 times. The lifetime of the material increased to 0.43 ms compared with the lifetime of Eu3+ in an aqueous medium of 0.1 ms.

Ag2S quantum dots (QDs) coated with thioglycolic acid (Ag2S QDs-TGA) have been synthesized in an organic solvent via a stepwise addition of reagents. When excited by a 980 nm laser, the near-infrared-emitting colloidal Ag2S QDs-TGA exhibit upconversion luminescence (UCL). The observed photoluminescence (PL) was attributed to the presence of ligand-modified Ag2S on the QD surfaces. Hence, upon dilution of the solution, the PL intensity initially increased before subsequently decreasing, accompanied by a blue shift in the PL spectra. The PL phenomena can be attributed to the increase in the amount of ligand-modified Ag2S on the QD surfaces upon dilution, which in turn affected the fluorescence resonance energy transfer (FRET) and re-emission of the surface energy level. The relations between the emission intensity of Ag2S QDs-TGA and the excitation power are investigated, and the results confirm that the UCL in Ag2S QDs-TGA can be ascribed to a two-photon-assisted absorption process via a real energy state.

The stickiness of acacia gum was used to assist in the ball milling of graphite in aqueous media. Graphite is successfully exfoliated through a “sticky tape” mechanism, to give a 2.06 mg mL−1 aqueous dispersion of graphene. PEG6000 doped with 0.4 wt% of as-prepared graphene nanosheets (GN) exhibited obviously growing enthalpies and increasing thermal conductivity by 260% over pure PEG6000.

In the present study, a kind of Eu(III) post-functionalized Zr(IV)-based metal-organic framework (UiO-66(COOH)2, Zr-MOF: Eu3+) was synthesized and utilized as an independently luminescent probe for sensing bilirubin (BR) in human serum, a biomarker of jaundice hepatitis. It can be served as a turn-off fluorescent switch for BR because its red emission from Eu3+ can be easily quenched by BR through a fluorescent resonant energy transfer (FRET) process between BR and its ligands, and as a result, BR is recognized successfully. Particularly, Zr-MOF: Eu3+ has shown many appealing properties, such as high sensitivity, quick response (less than 1 min), broad response window (0–15 μM), and excellent selectivity. Most importantly, a kind of portable test paper based on Zr-MOF: Eu3+ probe has been developed for directly assessing the level of BR in real human serum and further diagnosing bilirubin-related diseases via visually observing the luminescent color variation.

A new fluorescent probe based on terbium(III)-doped nanosheets was designed for detecting low-levels of dipicolinic acid (DPA), a biomarker of bacterial spores. The ability to detect ultra-low concentrations of DPA is therefore of great significance. First, Tb(III)-doped ytterbium hydroxide nanosheets were obtained by mechanical exfoliation from layered rare-earth hydroxide (LRH) materials. The morphology of the as-synthesized nanosheets was studied by transmission electron microscopy and atomic force microscopy. The Tb(III)-doped nanosheets are demonstrated to be highly sensitive to DPA, which remarkably enhances Tb(III) luminescence intensities at a wavelength of 544 nm. Furthermore, Tb(III) emission increases linearly with DPA concentration. Selectivity studies were conducted by adding different competing aromatic ligands to the sensing solution; however, their fluorescence responses were observed to be negligibly small in comparison with that of DPA. Our findings provide a basis for the application of Tb(III)-doped nanosheets for accurate, sensitive, and selective monitoring of DPA as a biomarker of anthrax.

In order to study the linkage effects between degree of polymerization and frequency domain dielectric spectroscopy characteristics of oil-paper insulation, the frequency domain dielectric response test platform of oil-paper insulation is set up. Complex permittivity of oil-paper insulation respectively composed by new or aged oil and insulation paper with different DP are tested, and complex permittivity of oil-paper insulation respectively composed by insulation respectively composed by new oil and insulation paper with different DP and low or high moisture content are tested. The test results are analyzed, and the analysis results show that the degree of polymerization of insulation paper has an influence on complex permittivity of oil-paper insulation though influencing the distribution of moisture and acids between oil and paper.

The work focused on improvement of the current response to NO and the reduction of response time of both NO and NO 2 . By adding a layer of TiO 2 catalyst layer, the shortcoming of NO insensitivity of traditional NASICON based amperometric NO 2 sensor was solved. TiO 2 was known as an n-type semiconductor and a high-performance NO oxidation catalyst. We separately applied different types of TiO 2 (rutile and Degussa P25) on the device and compared the test results with the traditional type without a catalyst layer. The results showed that the TiO 2 attached device exhibited a significant improvement to NO response, and P25 was better than rutile TiO 2 on account of the higher activity of anatase TiO 2 . In addition, TiO 2 also played a role of a semiconductor electrode, resulting in the increase of response to NO 2 . The response time of NO and NO 2 was separately shrunk from 153 s, 70 s to 77 s, 43 s owing to the P25 layer. The current responses were found to be barely affected by the coexistence of CO 2 .

An abnormal displacement change observed during the holding period in nanoindentation tests on a zirconia dental ceramic was reported in this paper. It was found that, at the initial stage of the holding period, the measured displacement versus time curves were similar in shape with the typical indentation creep curve reported in previous studies. As the holding lasted for long time, however, an evident reduction in displacement was observed for tests with high loading rate, implying that another unknown process, which might result in a decrease in displacement, would co-exist with creep during holding period. Elastic recovery was suggested to be one of the possible sources for such a displacement reduction. An empirical method was also proposed to eliminate the effect of this displacement reduction on the determination of hardness and Young’s modulus.

Correction of the contact area is an important step in the extraction of the hardness and Young's modulus from the analysis of nanoindentation unloading. One of the frequently adopted method for contact area correction is to relate the contact area A to the contact depth hc with a so-called "effective truncation length", hd, as A = C(hc + hd)2. In this paper, critical examinations on the applicability of the "effective truncation length" were conducted based on the analyses of nanoindentation load-displacement (P―h) curves, each of which contains several loading-unloading cycles, measured on four brittle materials. It was shown that the hd-value determined from a single P―h curve varies from material to material and exhibits an evident location-dependence for a given material, implying that hd cannot be considered simply as a correction for the rounded indenter tip. Possible sources which may result in the variation in the experimentally determined hd were discussed and it is concluded that hd should be considered to be an integrated or statistical measure of different influence factors. Further analyses proved that, despite of the existence of the significant variation in hd, the hardness and Young's modulus determined using the corresponding hd-value are proven to have an enough accuracy acceptable for practical applications.