Special Issue by Guest Editors: Novel Materials Design and Processing by External and Internal Reaction Fields: Reviews
Special Issue by Guest Editors: Novel Materials Design and Processing by External and Internal Reaction Fields: Papers
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Hideyuki NEGISHI, Norio OSHIMA, Kenji HARAYA, Keiji SAKAKI, Toru IKEGA ...
2006 Volume 114 Issue 1325 Pages
36-41
Published: 2006
Released on J-STAGE: January 01, 2006
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The electrophoretic deposition (EPD) process is one of several ceramic powder assembling technologies using a simultaneous colloidal process and electrochemical driving force. For the further development of the EPD technique, the possibility and the usefulness of preparing a thin and dense ceramic coating on non-electronically conductive porous tubular ceramics using the EPD technique was investigated. La
0.8Sr
0.2Co
0.8Sr
0.2O
3-δ (LSCF) was used as the deposition material and a porous alumina tube was used as the deposition substrate. Methanol (MeOH) was suitable as a dispersing medium for the LSCF powder. LSCF particles were positively charged in MeOH. For the fabrication of a uniform EPD layer, the cathode was placed in a porous alumina tube. The insides of the porous alumina tubes were filled with MeOH and the cathode did not make contact with the EPD bath. A 30 μm (200 g/m
2) thick uniform LSCF powder coating was obtained by EPD at 100 V for 10 min. After sintering at 1500°C for 5 h, a 20 μm dense membrane was obtained.
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Nobuo KIEDA, Tomoaki TOKUHISA
2006 Volume 114 Issue 1325 Pages
42-45
Published: 2006
Released on J-STAGE: January 01, 2006
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A novel process to immobilize oxide particles with electrolytically deposited metals as binders was proposed. Commercial TiO
2 photocatalyst particles, P25, were successfully immobilized on the surface of stainless steel substrates with Pd and Cu by this process. The effects of the conditions of electrolysis and the composition of the source solutions on the amount and the morphology of the particles accumulated on the surface were investigated. Addition of another particle with superior dispersibility, NanoTek, and sonication during electrodeposition were important to inhibit agglomeration of the particles and to achieve uniform and dense immobilization. Photocatalytic activity, which was evaluated by photobleaching of methylene blue solution, of the immobilized particles was as high as 50% of the particles suspended in the solution.
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Atsushi NAKAHIRA, Koichi KONISHI, Koji YOKOTA, Tetsuo HONMA, Hirofumi ...
2006 Volume 114 Issue 1325 Pages
46-50
Published: 2006
Released on J-STAGE: January 01, 2006
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In this paper, the synthesis of TiO
2 films and simultaneous P ion-doping for them were attempted by the anodic oxidation of titanium in phosphoric acid solution under various conditions (several concentrations of phosphoric acid solution and applied voltages on the anodic oxidation etc). Products obtained by this anodic oxidation of titanium were thin films and attached firmly to the surface of titanium. Although the surface of the oxide film obtained by an anodic oxidation in 0.25 M phosphoric acid at 350 V was flat, their oxide films were consisted of fine particles of 20-50 nm in diameter and had the unidirectional pores with the pore of about 200 nm to 1 μm in diameter. From XPS results, P
5+ ions were mainly doped near the surface of the oxide film, although P ions were existed as P
3+ inside the TiO
2 films, suggesting the successful doping of P ions, such as P
5+ and P
3+ into the TiO
2 films. Therefore, this anodic oxidation processing is useful for synthesis of TiO
2 films and simultaneous doping of P ions, leading to the development of a useful vector processing from an electro-chemical vector effect.
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Jun-ichi HAMAGAMI, Yuki ATO, Kiyoshi KANAMURA
2006 Volume 114 Issue 1325 Pages
51-54
Published: 2006
Released on J-STAGE: January 01, 2006
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A macroporous hydroxyapatite ceramic coating was fabricated on a titanium substrate by an electrophoretic deposition (EPD) process followed by a heat treatment in order to obtain high performance bioactive porous hydroxyapatite. The key of this EPD process is a formation of composite particles by using a heterocoaguration reaction, consisting of hydroxyapatite ceramic nanoparticles for the ceramic frame material and monodisperse polystyrene polymer microspheres for template component, in a suspension. Microstructure of the porous ceramic coating layer depends on electrophoretic deposition parameters, and on heat treatment conditions. Under the optimized fabrication conditions, the hydroxyapatite ceramic coating layer with well-controlled macroporous structure was obtained.
In vitro examination using a simulated body fluid revealed a good biocompatibility of the macroporous specimen.
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Tetsuo UCHIKOSHI, Seiichi FURUMI, Tohru S. SUZUKI, Yoshio SAKKA
2006 Volume 114 Issue 1325 Pages
55-58
Published: 2006
Released on J-STAGE: January 01, 2006
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The coating of conductive polypyrrole (Ppy) on nonconductive ceramic substrates was performed by polymerization of pyrrole (Py) in an aqueous solution. The Ppy film was characterized by scanning electron microscopy and conductivity measurements. Electrophoretic deposition of bimodal alumina suspension prepared with a phosphate ester was performed using Ppy film as a cathode. Fabrication of alumina ceramics with irregular shapes or complicated patterns were also attempted by sintering the deposits together with the Ppy coated substrates in air.
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Tohru S. SUZUKI, Tetsuo UCHIKOSHI, Yoshio SAKKA
2006 Volume 114 Issue 1325 Pages
59-62
Published: 2006
Released on J-STAGE: January 01, 2006
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Magnetic susceptibility is very small in feeble magnetic ceramics such as alumina, consequently, it had been very difficult to develop a textured microstructure in these ceramics by using a magnetic field. We have demonstrated, however, that textured microstructures in alumina, titania, zinc oxide can be prepared by colloidal processing in a high magnetic field followed by sintering. We applied this processing technique to alumina based composites. The degree of crystallographic texture was small in specimen sintered at the low temperature. The degree of orientation increased rapidly with increasing sintering temperature and depended on the grain size of alumina matrix. The grain size can be controlled by the content of YTZ particle as a second phase, the kind of dopant, sintering temperature, annealing temperature and annealing time.
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Akiko OBATA, Tatsuya FUJIMOTO, Toshihiro KASUGA
2006 Volume 114 Issue 1325 Pages
63-66
Published: 2006
Released on J-STAGE: January 01, 2006
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Bone-like hydroxyapatite (b-HA) formation abilities of β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) after autoclaving were evaluated by immersion tests using simulated body fluid (SBF). The b-HA formation was observed on an autoclaved β-TCP, while no deposition was observed on the non-autoclaved one. The b-HA formation on HA was observed to be enhanced after autoclaving. Decrease of surface potentials by autoclaving may enhance the b-HA formation abilities.
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Satoshi NAKAMURA, Masato KONNO, Keiichi KATAYAMA, Kimihiro YAMASHITA
2006 Volume 114 Issue 1325 Pages
67-71
Published: 2006
Released on J-STAGE: January 01, 2006
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Glass-ceramics of Na
2O-R
2O
3-P
2O
5-SiO
2 (Narpsio) consist of a skeleton structure of 12-tetrahedra-membered rings and exhibit a super Na
+ conductivity. Glass-ceramic Narpsio was proved to be electrically polarized through highly mobile sodium ions. Narpsio also shows relatively higher solubility in water. Taking into account of the water solubility and the chemical composition, the reactivity of polarized and non-polarized glass-ceramic Narpsio in the stimulated body fluid (SBF) were investigated in relation to bioactivity. After the 6 days' immersion of SBF, hydroxyapatite microcrystals aggregated semispherically were grown on the glass-ceramic Narpsio surfaces. Although the acceleration effects were under study, the growth rate was recognized to be higher in both of the negatively and positively charged surfaces. In analogy with polarized bioglasses, we confirmed the chemico-vector effects of glass-ceramic Narpsio for biomedical purpose. Additionally, glass-ceramic Narpsio, prepared by the locally biasing crystallization method, showed unreported microstructural changes of surfaces during chemical polishing with water, depending upon the direction of a biasing field. The phenomenon was interpreted as a mechanochemico-vector effect.
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Yuki SHIROSAKI, Kanji TSURU, Satoshi HAYAKAWA, Akiyoshi OSAKA, Seisuke ...
2006 Volume 114 Issue 1325 Pages
72-76
Published: 2006
Released on J-STAGE: January 01, 2006
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γ-Methacryloxypropyltrimethoxysilane (γ-MPS) was grafted on a silicone elastomer by emulsion polymerization in order to improve cytocompatibility. The wettability of the grafted surface was evaluated with a contact angle toward distilled water. By grafting within 30 min at 60°C, the contact angle was reduced from 110° to about 70° while it remained almost constant for longer grafting. A larger number of osteoblastic cells (MC3T3-E1) and fibroblast cells (L929) proliferated on the surface modified with γ-MPS compared with the original silicone surface. After culturing for 7 d, the cells completely covered the grafted surface and even formed a cell layer.
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Masakazu KAWASHITA, Hiroshi SHIMATANI, Satomi ITOH, Rei ARAKI, Gikan H ...
2006 Volume 114 Issue 1325 Pages
77-81
Published: 2006
Released on J-STAGE: January 01, 2006
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Polyethylene (PE) and polyethylene terephthalate (PET) substrates were irradiated by the simultaneous use of oxygen (O
2) cluster and monomer ion beams to improve their hydrophilic property. The hydrophilic groups such as COOH and C-OH groups were formed at the PE and PET surfaces by the irradiation. The contact angles of PE and PET substrates were decreased remarkably by the irradiation. Bioactive calcium silicate (CS) gel layer was successfully formed on the irradiated PE and PET substrates, and the irradiated and CS-coated PE and PET substrates formed uniform bonelike apatite layer on their surfaces in SBF within 4 d.
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Masanobu KAMITAKAHARA, Chikara OHTSUKI, Yuko KOZAKA, Shin-ichi OGATA, ...
2006 Volume 114 Issue 1325 Pages
82-86
Published: 2006
Released on J-STAGE: January 01, 2006
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Control of the surface reactivity of bioactive materials to surrounding body fluids is essential in the design of novel bone-repairing materials, because apatite formation on bioactive materials is governed by the dissolution of constituents from the materials and the nucleation of hydroxyapatite on the resultant surface. These bioactive materials are therefore recognized as “chemicovector ceramics”, as described by Yamashita et al. Glass-based bioactive materials have the benefit of easy control of their bioactivity and bioresorbability, as their surface reactivity in body environments can be easily controlled by varying their composition. Consequently, glass-derived biomaterials are attractive for use in the fabrication of porous glass-ceramics as bone substitute and scaffold materials for bone regeneration. We anticipated that a glass-ceramic containing tricalcium phosphate (TCP; 3CaO•P
2O
5) and diopside (CaO•MgO•2SiO
2) would show high bioactivity and high mechanical strength, as well as bioresorbability. In this study, glass-ceramics were prepared with compositions of
x(3CaO•P
2O
5)•(100-
x)(CaO•MgO•2SiO
2), where
x=0, 38, 50, or 60 mass%, and their bioactivity evaluated by examining
in vitro apatite formation in a simulated body fluid (SBF). Pulverized glasses of each composition were compacted and heated to obtain the bulk glass-ceramics. When the compacted materials were sintered at 1200°C, whitlockite (β-TCP) and diopside precipitated from the glasses with compositions where
x=38, 50, 60 mass%, and diopside alone precipitated when
x=0. The prepared glass-ceramics containing β-TCP and diopside formed apatite on their surfaces within 7 d in SBF. This result indicates that these glass-ceramics have the potential to show bioactivity. Porous glass-ceramics with continuous pores of about 500 μm were successfully prepared with the above compositions. These porous glass-ceramics containing β-TCP and diopside are expected to be useful as scaffold materials for bone repair.
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Toshiki MIYAZAKI, Hiroko AKITA, Eiichi ISHIDA, Masahiro ASHIZUKA, Chik ...
2006 Volume 114 Issue 1325 Pages
87-91
Published: 2006
Released on J-STAGE: January 01, 2006
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Several kinds of ceramics called bioactive ceramics have attractive features such as direct bone-bonding in living body. However, they are much more brittle and much less flexible than natural bone. Previous studies reported that the essential condition for materials to show bone-bonding property, i.e., bioactivity, is formation of biologically active apatite on their surfaces after exposure to the body fluid. The same type of apatite formation can be observed even in a simulated body fluid (SBF, Kokubo solution) with inorganic ion concentrations similar to those of human extracellular fluid. Several functional groups such as Si-OH and Ti-OH are known to trigger nucleation of the apatite in body environment. This is significantly enhanced by the release of Ca
2+ from the materials. These findings suggest that organic modification of bioactive inorganic components would provide bioactive materials with mechanical performances analogous to those of natural bone. We previously synthesized bioactive organic-inorganic hybrids from alkoxysilane that provides Si-OH groups and calcium salts that release Ca
2+ by organic modification with hydroxyethylmethacrylate (HEMA). If another type of functional group can be incorporated into the hybrids, useful guideline for designing bioactive materials with different biological and mechanical properties would be obtained. In this study, we synthesized organic-inorganic hybrids from HEMA by addition of tetraisopropyl titanate (TiPT) and CaCl
2. Their apatite-forming ability was examined in SBF. The obtained hybrids formed the apatite in SBF within 7 d, when they were added with appropriate amount of CaCl
2. It was speculated that the apatite deposition was induced by Ti-OH groups formed on the hybrids and the release of Ca
2+. The chemicovectors including the ion release govern the apatite formation on the hybrids. Mechanical properties of the hybrids were also evaluated by tensile test. They showed Young's modulus analogous to human articular cartilage.
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Takafumi AKAMATSU, Toshihiro KASUGA, Masayuki NOGAMI
2006 Volume 114 Issue 1325 Pages
92-96
Published: 2006
Released on J-STAGE: January 01, 2006
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When zinc metaphosphate glass powders were mixed with water, their hydration immediately started with an exothermic reaction; the mixture of the glass powders and water was completely converted into a translucent hydrogel (ZP gel) after 2 d. No hydrogelation occurred when water was mixed with beryllium metaphosphate, strontium metaphosphate, or barium metaphosphate glass powders. The long-chain phosphate structures in beryllium metaphosphate glass powders were almost not broken after mixing water, while those in strontium metaphosphate and barium metaphosphate glass powders were easily broken as shown in our earlier work. This result suggested that hydrogelation occurs after mixing water and the metaphosphate glasses with adequate bonding strength between bivalent metal ion and non-bridging oxygen in the phosphate chain structure. The phosphate chains in the ZP gel were gradually broken, resulting in an increase of orthophosphate amount. Crystalline phases were observed in the ZP gel after 12 d of mixing with water the glass powders. The proton conductivity of the ZP gel, which showed 5.7 mS/cm at 30°C, was not influenced by the precipitation of the crystalline phases.
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Akira WATANABE, Takehisa FUKUI, Kiyoshi NOGI, Yoichi KIZAKI, Yuji NOGU ...
2006 Volume 114 Issue 1325 Pages
97-101
Published: 2006
Released on J-STAGE: January 01, 2006
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We report high-quality and high-density Bi
3.25La
0.75Ti
3O
12 ceramics prepared by sintering at a low temperature of 900°C from the nanosized powder with a diameter around 100 nm synthesized by the flash creation method. The densification at 900°C, which was 300°C lower sintering temperature compared with conventional solid-state reaction, enables us to obtain the ceramics showing a remanent polarization of 14.5 μC/cm
2, a coercive field of 50 kV/cm and a leakage current of ~10
-9 A/cm
2. The superior properties are indicated to originate from lower defect concentration achieved by the low temperature sintering.
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Shingo OHTA, Hiromichi OHTA, Kunihito KOUMOTO
2006 Volume 114 Issue 1325 Pages
102-105
Published: 2006
Released on J-STAGE: January 01, 2006
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We investigated thermoelectric properties of 20-%-Nb-doped SrTiO
3 at high-temperature (300-1000 K) using single-crystalline epitaxial film, polycrystalline film (average grain size ~200 nm) and ceramic (average grain size ~20 μm) samples to clarify the effect of grain boundaries on the thermoelectric performance. Although carrier concentration and Seebeck coefficient of all samples showed no significant differences, Hall mobility of the polycrystalline film was extremely small («10
-1 cm
2V
-1s
-1 at 300 K) as compared to those of the epitaxial film and the ceramic sample (~3 cm
2V
-1s
-1). However, it drastically increased with increasing temperature and exhibited the value similar to those of the epitaxial film and the ceramic sample above 700 K. The thermoelectric figure of merit for 20%-Nb-doped SrTiO
3 was found to reach 0.35 at 1000 K irrespective of the grain size.
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Motohide MATSUDA, Kyunosuke NAKAMOTO, Michihiro MIYAKE
2006 Volume 114 Issue 1325 Pages
106-109
Published: 2006
Released on J-STAGE: January 01, 2006
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The microwave-assisted self-heating profile and sinterability of porous NiO-(Ce, Sm)O
2 composites with 25, 50 and 75 mass% NiO, which were prepared by heating at 800-1200°C for solid oxide fuel cell applications, were investigated. The porous NiO-(Ce, Sm)O
2 composites were heated to ca. 1300°C within 5 min in a microwave field. The sinterability of the self-heating NiO-(Ce, Sm)O
2 composites in a microwave field was dependent upon the mixing ratio of NiO and the pre-heating temperature. A large shrinkage of over 20% was achieved for the 25 mass% NiO-containing composites microwave-heated at 1300°C for 2 h after the pre-heating at 800°C. The sinterability was comparable to that by conventional sintering at 1400°C for 2 h.
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Yoshinori YONESAKI, Katsuhisa TANAKA, Kazuyuki HIRAO
2006 Volume 114 Issue 1325 Pages
110-113
Published: 2006
Released on J-STAGE: January 01, 2006
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Second-harmonic generation (SHG) has been observed in optically poled 15Nb
2O
5•85TeO
2 glasses doped with V
2O
5 and Tb
2O
3. The SH intensity of optically poled V
2O
5-Tb
2O
3-codoped glass is approximately 4-fold that of optically poled V
2O
5-doped glass, whereas the SH intensity of the optically poled Tb
2O
3-doped sample is approximately one-fifth that of the V
2O
5-doped sample, which means that the terbium ions contribute to the enhancement of χ
(2) only when the vanadium ions coexist.
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Shingo KATAYAMA, Noriko YAMADA, Koichi KIKUTA, Masanobu AWANO
2006 Volume 114 Issue 1325 Pages
114-119
Published: 2006
Released on J-STAGE: January 01, 2006
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The organosilxane-based organic/inorganic hybrid was synthesized by adding 3-glycidoxypropyltrimethoxysilane (GPTMS) to an aqueous solution of tungstic acid and gelling it at 70-150°C. The FT-Raman and
13C NMR studies revealed that the alkoxy and epoxy groups of GPTMS were subject to hydrolysis and ring-opening reaction, respectively. The
29Si NMR study revealed that the inorganic component derived from tungstic acid appeared to have Si-O-W bonds with the GPTMS-derived siloxane network. The GPTMS-derived organic/inorganic hybrid containing the inorganic component derived from tungstic acid was transparent and colorless. In addition, it showed the photochromism that resulted from the incorporation of the inorganic component derived from tungstic acid into the GPTMS-derived organic/inorganic hybrid. A broad peak around 880 nm with a shoulder peak around 650 nm was observed in the spectra after the UV-irradiation, meaning two kinds of
d-d bond intervalence transition states exist in the organic/inorganic hybrid. Assuming that the photochromism was the first-order reaction, the reaction rate constant was estimated to be 1.9×10
-1 min
-1.
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Hiroyo SEGAWA, Yasuo YAMAZAKI, Tetsuji YANO, Shuichi SHIBATA
2006 Volume 114 Issue 1325 Pages
120-124
Published: 2006
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The mechanism of “top-gathering” pillars and the controllability of top-gathering pattern formation were investigated. Two-dimensional pillar arrays with micrometer repetitions have been fabricated from a hybrid organic-inorganic material by photolithography. The type of array structure formed depending on the distance between neighboring pillars. From in situ observation during drying, it was found that capillary force is affected by the distance between the pillars. Such pillars of 16 μm height were gathering, and top-gathering units could be obtained when the distance between neighboring pillars is less than 8 μm. Gathering units composed of four pillars can be formed periodically by controlling the arrangement of the pillars.
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Kiyoharu TADANAGA, Toshitsugu SUEKI, Atsunori MATSUDA, Tsutomu MINAMI, ...
2006 Volume 114 Issue 1325 Pages
125-127
Published: 2006
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Inorganic-organic hybrid films with a maximum thickness of about 40 μm were prepared from vinyltriethoxysilane (VTES) through a sol-gel process. UV light from a high-pressure mercury lamp was irradiated through a photomask on the hybrid films from VTES. IR and
29Si NMR spectra of the coating films showed that C=C bonds in VTES were polymerized by UV irradiation. Micropatterns with a maximum height of about 40 μm were formed by the etching of unirradiated area of the films.
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Special Issue by Guest Editors: Novel Materials Design and Processing by External and Internal Reaction Fields: Notes