Yoshihiro Takahashi

Yoshihiro Takahashi
Tohoku University | Tohokudai · Department of Applied Physics

Doctor of Engineering

About

141
Publications
6,431
Reads
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1,852
Citations
Introduction
1. Glass/amorphous material for photonic applications: Pockels effect and second-harmonic generation. 2. Photoluminescence and afterglow for new applications: Temperature-sensing for human body using ZrO2 probe. 3. heat energy storage based on glass material toward thermal management.
Additional affiliations
October 2014 - January 2021
Tohoku University
Position
  • Professor (Associate)
December 2006 - September 2014
Tohoku University
Position
  • Professor (Assistant)
April 2004 - December 2006
National Institute for Materials Science
Position
  • Fellow
Education
April 2000 - March 2003

Publications

Publications (141)
Article
Second-order optical nonlinearities, d33 values, of fresnoite-type crystals, Ba2TiSi2O8 (BTS), Sr2TiSi2O8 (STS), and Ba2TiGe2O8 (BTG), have been evaluated by measurements on transparent surface-crystallized glasses consisting of fresnoite-type crystals with the Maker fringe technique. It is found that all these crystals show large d33 values, i.e.,...
Article
In situ measurement of boson peak in several glasses was performed during the crystallization process to elucidate crystallization dynamics. In this study, it was experimentally illustrated that a drastic decrease in elasticity and damping of the boson peak occurred during the crystallization process when T/Tg∼1.1–1.2. A possible mechanism for the...
Article
Full-text available
Development of minimally invasive and site-selective biological temperature sensing is quite important in medical field. This study presents a novel temperature sensing technique based on afterglow and optically-stimulated luminescence (OSL). The dependence of afterglow photoluminescent intensity on the environmental temperature of zirconia (ZrO2)...
Article
Full-text available
Energy storage technology is crucial for a sustainable society, and its realisation strongly depends on the development of materials. Oxide glass exhibits high durability. Moreover, the amorphous structure of the glass without periodic ordering demonstrates excellent formability and controllability, thus enabling a large-scale production. These fac...
Article
Full-text available
Silicate glass has been used for long time because of its advantages from material's viewpoint. In this paper, we report the observation of Pockels effect by Mach-Zehnder interferometer in polycrystalline ceramics made from a ternary silicate glass via crystallization due to heat-treatment, i.e., glass-ceramics. Since the silicate system is employe...
Article
Spin-ladder cuprates such as La5Ca9Cu24O41 are promising materials for advanced thermal management applications owing to their highly anisotropic and dynamically controllable thermal conductivity originating from spin ladders. Therefore, the orientation control of spin ladders is required in film fabrication methods that are extensively used in dev...
Article
Full-text available
Photoluminescence provides information about the surrounding environment. In this study, aiming to develop a non-invasive deep body-temperature sensing method, we investigated photoluminescence properties of afterglow zirconia (ZrO2) by pulsed near-infrared (NIR) light irradiation based on the biological temperature. Pulsed light irradiation produc...
Article
Noninvasive and site-selective temperature sensing is required in biology and advanced medicine. Recently, we proposed a new concept for temperature sensing, which is based on afterglow and optically-stimulated luminescence [Sci. Rep. 10, 2242 (2020)]. Here we assessed the thermal sensitivity of afterglow zirconia and clarified the potential of thi...
Article
Full-text available
Dynamic control of heat flow for applications in thermal management has attracted much interest in fields such as electronics and thermal engineering. Spin-chain ladder cuprates are promising materials to realize dynamic control of heat flow, since their magnon thermal conductivity is sensitive to the hole density in the spin ladders, which can be...
Article
Full-text available
Oxide glass is an industrial material with advantages such as optical transparency and shaping ability of the melt, but at the same time, it is a bad conductor of heat due to its disordered structures. Therefore, heat dissipation in glass components often becomes a problem and its applications to the thermal management has been limited to use as a...
Article
Optical modulation based on second-order optical nonlinearity is required to control a light-wave for telecommunication with optical-fiber network, and the controlling device is basically constructed using a single crystal material. To fabricate an optical device material having the connectivity to glass fiber, glass-ceramic (GC) processing is effe...
Article
Full-text available
Chemically strengthened glass is widely used for screen protection in mobile devices, and its strengthening processes and application fields have rapidly diversified. The origin of the strength is residual compressive stress induced by ion exchange, and the stress evaluation has been performed via the photoelastic effect. However, for a deep unders...
Article
Full-text available
Phase change material (PCM), which enables heat storage based on phase transition, plays an important role for efficient energy utilization. This paper briefly describes our recent study about all-solid PCM by combination of vanadium dioxide (VO2) with latent heat storage capacity and multicomponent glass, i.e., VO2-dispersed glass. A B2O3-P2O5-V2O...
Conference Paper
We have investigated atomic-scale structures in 2-step ion-exchanged strengthened glasses by using polarized micro-Raman spectroscopy for non-destructive evaluation of the compressive stress.
Article
This study describes the investigation of photoluminescence (PL) and afterglow properties of samarium ion (Sm³⁺)-doped zirconia and the comparison with those of pure zirconia. The pure sample exhibits bluish PL and afterglow upon excitation by ultraviolet light, whereas white-to-reddish PL and white afterglow are detected by means of visual observa...
Article
We have fabricated perfectly-surface-crystallized glass-ceramics (PSC-GCs) consisting of polar frenoite-type Sr 2 TiSi 2 O 8 by different crystallization-process conditions, i.e., isothermal treatment at 880 °C for 72 h and 960 °C for 1 h, and have examined their Pockels effect in this study. The PSC-GCs obtained by the lower-temperature process ex...
Article
Materials with high thermal conductivity have attracted considerable attention for thermal management of electronic devices. Therefore, focusing on formability and anisotropic heat transfer, we fabricated glass-ceramics containing the spin-chain compound SrCuO2 and demonstrated its high thermal conductivity in the previous work, where SrCuO2 is kno...
Article
Oxide glasses generally have low thermal conductivity due to their disordered structures. Here, a fabrication method to provide them with high thermal conductivity while retaining their optical transparency is proposed. It consists of dispersing ∼20 μm MgO crystals in a glass matrix and matching their refractive indexes to prevent the decrease of t...
Article
We investigated the long-lasting photoluminescence (LLP) properties in a commercial zirconia powder with a monoclinic system after thermal treatment at different temperatures. Clear-blue photoluminescence and LLP were observed in the zirconia without emissive dopants subjected to thermal treatment at 1400 °C. Decay curve measurements revealed a pro...
Article
We investigated the Pockels effect in polycrystalline materials consisting of highly oriented polar fresnoite-type Sr2TiSi2O8 fabricated using perfectly surface-crystallized glass-ceramics (PSC-GCs). The chemical composition of the precursor glass was shown to significantly affect the crystallized texture, e.g., the crystal orientation and appearan...
Conference Paper
We fabricated the highly-oriented glass-ceramics in silicate systems, and succeeded in estimating the Pockels and second-order nonlinear optical constants comparable to common inorganic nonlinear-optical crystals.
Conference Paper
We fabricated the glass-ceramic fiber with nonlinear-optical crystal, which is radially-crystallized. Visible second-harmonic generation and its intensity-independence on the fundamental polarization were demonstrated.
Conference Paper
Creation of polar Sr2TiSi2O8 crystal was attempted by CO2 laser-irradiation on the glass surface, aiming to control of the crystal-domain structure, and the second-harmonic generation was clearly observed in the laser-crystallized region.
Article
We fabricated glass-ceramics composed of emissive nanocrystals that show variation in photoluminescence coloration. The change in emission color is based on the amorphous-to-crystalline phase transformation in a Mn-containing zincogermanate glass. The transformation occurred at a 50 °C temperature range (538–588 °C), resulting in a change in photol...
Article
Recently, we have developed the borosilicate glass, in which ZrO2 phase is singly crystallizable, and has found an emissive monoclinic ZrO2 dendrites in the resulting GCs. In order to promote the formation of monoclinic phase, we have examined the effect of substitution of alumina Al2O3 for ZrO2 in the precursor glass composition, i.e., 15Na2O-(15-...
Article
Chemically strengthened glass has become essential in our daily lives and the demand is rapidly increasing in a variety of fields. However, the conventional cutting process is not applicable because of its tough layer with the compressive stress. To achieve higher-throughput production of the glass, we report spatially selective weakening of the co...
Article
The control of heat flow has become increasingly important in energy saving and harvesting. Among various thermal management materials, spinon thermal conductivity materials are promising for heat flow control at microscales because they exhibit high, anisotropicthermal conductivity resulting from spin chains. However, there has been only little de...
Article
We prepared SrCuO2 thin film by radio-frequency magnetron sputtering on glass substrate and have investigated its post-annealing effects on structure and thermal conductivity. The as-sputtered film belongs to two-dimensional spin system SrCuO2, namely, layer-type SrCuO2, which has a possibility of exhibiting high, anisotropic thermal conductivity b...
Article
Functional nanocrystals have received considerable attention because of their various applications. Although glass-ceramic (GC) processing is recognized as promising for preparation of nanostructured material, it is difficult to use the materials as nanocrystals as in. This study provides a possible way to obtain nanocrystals by irradiation of fund...
Article
We prepared a borosilicate glass, in which the ZrO2 phase is singly crystallizable, i.e., 15Na2O–15ZrO2–30B2O3–40SiO2 glass, and investigated the texture and morphology of the resulting glass-ceramics. ZrO2 dendrites with a tetragonal system (high-temperature phase) were developed as initial phase, and the tetragonal phase was transformed to the mo...
Article
Study on visible light response of photocatalytic materials is very important research area for future energy society. Generally, in conventional photocatalysts, visible light response is provided by defect introduction. This phenomenon is based on formation of trap level between valence and conduction band. In our previous report, we have already...
Article
We performed depth analysis of a compression layer in Corning Gorilla Glass 3, one of commercialized chemically-strengthened glasses, using depth-resolved micro-Raman spectroscopy. We obtained a depth variation of Raman spectra and an ion-exchange rate of Na for K was determined by energy dispersive X-ray spectroscopy.We found that a peak position...
Article
We have synthesized spinon thermal conductivity materials in Sr–Cu–O system by glass-ceramics technique. The materials are promising for active control of thermal energy in microelectronic devices because of high and anisotropic thermal conduction, its controllability, and electric insulation. Nevertheless, research on these materials has been limi...
Article
We prepared SrCuO2 film by radio-frequency magnetron sputtering on silica glass and have investigated structure change induced by super-band-gap light. An X-ray diffraction pattern shows that the as-sputtered film is composed of (001)-oriented SrCuO2 nanothick crystals belonging to tetragonal system, i.e., the layer-type SrCuO2. Raman-scattering sp...
Article
Full-text available
We have synthesized Mn4+-doped mixed tetragermanate phases in the Li2Ge4O9LiNaGe4O9 system, i.e., Li(Li,Na)Ge4O9, by a glass-ceramic technique using stoichiometric precursor glasses, and have examined the effect of substitution of Na on their photoluminescence properties. The tetragermanate phases indicated clear red emission based on a 2E→4A2 tran...
Article
We examined the crystallization and crystal growth of ZnO in the viscoelastic supercooled liquid (SCL) phase based on microscopic and spectroscopic observations. The resulting glass–ceramics exhibits complex ZnO dendrites that precede the formation of Zn-rich regions because of phase separation. Compressive stresses are concentrated at the interfac...
Article
We compare the boson peaks (BPs) observed in low-frequency Raman scattering with the BPs observed in low-temperature specific heat in many oxide glasses. We find a linear correlation of the maximum positions between the Raman BP and specific-heat BP regardless of the constituents. In addition, we show that several chalcogenide and molecular glasses...
Article
We have investigated the nano-structure of TiO2-precipitated CaO-B2O3-Bi2O3-Al2O3-TiO2 (CaBBAT) glass–ceramics, and discussed the effect of the addition of SnO. 119Sn Mössbauer spectra of the Sn-doped glass suggest that most of the SnO was oxidized during melting. Selective crystallization of TiO2 occurred independently of SnO addition in the homog...
Article
We prepared SnOZnOB2O3 system glasses by means of melt-quenching technique with different melting-process temperatures in range of 11001500 °C, and examined the impact of the process temperature on photoluminescent (PL) property. The glass obtained at 1100°C showed clear PL band at ∼2.8 eV at room temperature. As elevating the process temperature,...
Article
We assessed the photoluminescence performance characteristics of Mn4+-doped tetragermanate and silicogermanate phases with a benitoitetype structure. We observed a visible red emission based on the 2E→4A2 transition in the doped benitoite-type tetragermanate. The partial substitution of Si for Ge, resulting in SrGe3.495Mn0.005Si0.5O9, improved the...
Article
High thermal conductivity materials are in great demand for heat-flow control and heat dissipation in electronic devices. In this study, we have produced a glass-ceramics that contains spin-chain compound SrCuO2 and have found that the glass-ceramics yields high thermal conductivity of ∼5 W K−1 m−1 even at room temperature. The glass-ceramics is fa...
Article
Full-text available
Glass-ceramics grown from a glass of the composition Sr 2 TiSi 2.45 O 8.9 (STS 45) are analyzed by scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). Oriented nucleation with the c-axes preferably perpendicular to the surface is detected. A very strong 001-texture is observed after only 10 mm of growth into the bulk, ma...
Article
We present the results of low-temperature (similar to 5 to 20 K) specific-heat measurements performed in numerous oxide glass systems. These results allow us to elucidate the impact of the system or component on the excess specific heat, which when plotted on C-p/T-3 vs T appears as a broad band known as the boson peak (BP). By integrating our expe...
Article
Full-text available
The effect of thermal annealing on low-temperature excess heat capacity was investigated in fresnoite (Ba2TiSi2O8) glass. The amplitudes of the excess heat capacity decreased, and their positions shifted to a higher temperature by relaxation or crystallization. In particular, we revealed that the change in the excess heat capacity during transition...
Article
Full-text available
The authors aim to report the largest enhancement of photocatalytic activity by chemical etching in anatase-type TiO2 crystallized glass. Optimization of several conditions for crystallization behavior and chemical etching to realize the nano-structured ceramics (NSC) has been performed in the crystallized glass. NSC-fabrication by chemical etching...
Article
We synthesized the lithium-tetragermanate (Li2Ge4O9) phase doped with Mn4+ by glass-ceramics technique using the stoichiometric glass-precursor with different MnO2 concentrations, i.e., 20Li(2)O-80GeO(2)-xMnO(2) (x = 0.1-0.7), and examined their photoluminescent property. The doped phase showed clear red-emission at room temperature, and the intern...
Article
A production of polycrystalline phase with glassy precursor, i.e., glass-ceramics processing, has a great potential to fabricate the sophisticated materials. In this study, we have prepared the Bi2O3–Fe2O3–BaO–B2O3 system precursor, in which BiFeO3 phase is crystallizable, and examined the phase formation and physical properties in resulting glass-...
Article
The propagation losses for fresnoite-phase crystallized glasses fabricated from 35BaO–15TiO2–50GeO2, 28BaO–18TiO2–54SiO2, and 35SrO–20TiO2–45SiO2 (STS45) glasses using a cut-back technique are reported. The values are comparable with those for LiNbO3 waveguide single crystals and transparent Y3Al5O12 ceramics. In addition, the propagation loss data...
Article
Since stillwellite-type ferroelectric LaBGeO5 shows the intriguing physical properties by the doping/substituting-modification, the stillwellite-type glass-ceramics has been studied extensively from viewpoint of material engineering. In this study, we examined how the Nd-doping affects the glassy ferroelectric LaBGeO5 and its modified sample, LaBSi...
Article
Low-frequency Raman measurement was performed in alkali and alkaline-earth silicate glasses to elucidate the effect of introduction of network modifiers on boson peak nature. Our study illustrated that introduction of small/medium ions tended to increase in the boson peak frequency (ωBP), whereas the introduction of large ions tended to decrease th...
Article
In this study, we have investigated the effects of heat-treatment condition and SiO2 addition on the crystallization behavior and chemical durability of TiO2–ZnO–B2O3–Al2O3 (TZBA) glass. Systematic analysis indicated that not only the precipitated phases (rutile, anatase, and brookite) after crystallization but also the chemical durability of TZBA...
Article
We describe the preparation of [(100 − y)/4](SrO–BaO–2Nb2O5)–yP2O5 (SBNPy) glasses and glass-ceramics with the Sr0.5Ba0.5Nb2O6 (SBN50) phase, using a conventional process, and the analysis of the chemical stability of the materials in water. The SBNPy glasses and glass-ceramics consist of orthophosphate (Q0) and pyrophosphate (Q1) units with strong...
Article
Phase separation often makes glass structure inhomogeneous. Nevertheless, a uniform texture consisting of single-crystal domains has been found by crystallization in nonstoichiometric glass, i.e., perfect surface-crystallization (PSC). Although the PSC is probably caused by evolution of SiO2-rich amorphous nanoparasites on the domain, its mechanism...
Article
Stoichiometric glassy germanate is an important material in geophysics and materials science. Despite the binary Li2O−GeO2 system being primitive, its crystallization mechanism remains undetermined. In this study, we investigated crystallization and structural ordering in glassy ferroelectric Li2Ge4O9. Using isothermally and nonisothermally prepare...
Article
We prepared a niobiophosphate-glass-crystallizing tungstenbronze-type Ba2NaNb5O15 and measured elastic light scattering spectra in situ in the glass-ceramics fabrication regime. We found that the studied glass possesses a strong tendency for phase separation into Al2O3P2O5 and Nb-rich regions prior to crystallization. It is suggested that the tungs...
Article
Uniform and highly oriented crystalline layers with submillimeter thickness have been demonstrated recently by crystallization in nonstoichiometric precursor glass, i.e., perfectly surface-crystallized glass-ceramics (PSC-GCs). Although the origin of PSC in the SrO−TiO2−SiO2 system was interpreted by the presence of SiO2-rich amorphous nanoparasite...
Article
Full-text available
Glass-ceramics (GCs) are materials obtained from the crystallisation of functional phases in glass, and have a structure that the crystallised phase embedded in the glass matrix. Glass-forming oxides are commonly added to the functional phases to improve the stability of precursor glass; however, the issue of glass-ceramics permitting the presence...
Article
We have examined the dependence of the structure of BaO–TiO2–GeO2 (BTG) glass on the temperature at which the BTG glass melt is held in the molten state (called the “melt temperature” in the present paper). The absorption coefficient and refractive index of the BTG glass increase with increasing melt temperature because of the reductive conditions....
Article
Usually, phosphor is composed by host crystal and doped rare-earth ion which is an efficient luminescent centre. However, rare-earth elements have considerably small Clarke number and are produced from specific area. Since titanate and silicate minerals are relatively deposited in the earth’s crust, we focused on titanosilicate mineral with excelle...
Article
Full-text available
Inelastic light scattering has been utilized for examining the structure of glass and its relaxation. However, the quasi-elastic-light-scattering (QLS) phenomenon has not been addressed in much detail. In this study, we observed pronounced QLS-intensity variations in two temperature domains-supercooled liquid (SCL) state (α-relaxation regime) and b...
Article
We have examined the structure and the crystallization behavior of the 13TiO2–xZnO–17Al2O3–(70−x)B2O3 (TZAB) glass. Coordination number of B2O3 and Al2O3 is changed by substitution of B2O3–ZnO, whereas coordination states of TiO2 and ZnO are not affected by the substitution. With increasing amount of ZnO, network forming AlO4 increases instead of n...
Article
We have examined the correlation between the thermal and optical properties of 30BaO-15TiO2-55GeO2 glass and its mode of preparation, i.e., the different temperatures at which the glass melts were held in a molten state (melt temperature). The changes in the absorption coefficients and the refractive indices, which increased with the increasing mel...
Article
A wide band-gap semiconductive oxide Zn2GeO4 has recently attracted considerable interest because it is a multifunctional material; excellent photoluminescent (PL) and photocatalytic property, high-capacity anode for lithium batteries, and so on. Recently, present authors' group have fabricated transparent Zn2GeO4-nanocrystallized glass from a lith...
Article
Low-frequency Raman scattering and TEM observations were conducted in 1Li2O–2SiO2 glass subjected to annealing at maximum homogeneous nucleation temperature (∼460°C) to elucidate the annealing effect on Boson-peak behavior and its relation to the structural evolution in nanoscale. It is suggested that the 1Li2O–2SiO2 glass possesses a successive me...
Article
Full-text available
Glass-ceramics (GC) consisting of nano-sized Nb-dielectrics were fabricated in BaO–Na2O–P2O5–Nb2O5 system, and their crystallization and physical features were studied. Precursor of 0.67(2BaO–0.5Na2O)–1P2O5–2.5Nb2O5 glass co-crystallized Ba2NaNb5O15 (BNN) and NaNbO3 phases, which are about 10 nm in size, and resulting GC possessed an optical transp...
Article
Li2Ge4O9 is known to be a ferroelectric phase with Curie temperature at Tc ∼ −93 °C. In this study, we found both the lowest-frequency phonon and heat-capacity anomalies around 100 °C in the Li2Ge4O9 phase, demonstrating their presence in the structural phase-transition. The phase transition is probably triggered by regularization of distorted GeO6...
Article
The authors investigate the structural change of a ZnO–P2O5 sintered matrix for the preparation of SnO-doped zinc phosphate (SZP) glass using a platinum crucible. Heat treatment of zinc oxide and ammonium phosphate at 800°C causes the formation of a Zn2P2O7-like species, which is effective in preventing damage to the platinum crucible. Although the...
Article
Crystallization behavior of the oxide semiconductor ZnO in zinc borate glass was investigated. The precipitated crystalline phase of glass ceramics containing a small amount of Al2O3 was α-Zn3B2O6 whereas that of the glass ceramics containing a large amount of Al2O3 was ZnO. It was found that the c-oriented precipitation of ZnO in a glass ceramic w...